Sample records for ac joint dislocation

  1. Arthroscopic treatment of acute acromioclavicular joint dislocation by coracoclavicular ligament augmentation.

    PubMed

    Liu, Xudong; Huangfu, Xiaoqiao; Zhao, Jinzhong

    2015-05-01

    Coracoclavicular (CC) ligament augmentation has been a method to treat acromioclavicular (AC) joint dislocation in recent years. The purpose of this paper is to describe our arthroscopic CC ligament augmentation technique in treating type III and V acute AC joint dislocations and to report the early clinical and radiological results. From 2010 to 2011, twelve patients suffering from acute type III or V AC joint dislocations were arthroscopically treated in our department, by CC ligament augmentation after AC joint reduction. The post-operative outcomes were assessed through physical examination, radiographic examination and the Constant-Murley Shoulder Score. All patients post-operatively experienced anatomical reduction in their AC joint dislocation. No intraoperative complications occurred. At a mean follow-up at 24 months (ranging from 18 to 32 months), the mean Constant-Murley Shoulder Score significantly improved from 24.3 pre-operatively to 91.1 post-operatively. No neurovascular complications or secondary degenerative changes of the AC joint were detected in any of the patients. In one case, a second dislocation occurred 1 month post-operation because the patient had had another traumatic injury. This patient accepted a revision operation, but his AC joint eventually fixated into a subluxated position after his second injury. Based on the resultant successful repair in all cases, the arthroscopic CC ligament augmentation method has thus far proven to be a safe and reliable technique for treatment of acute type III or V AC joint dislocation. The arthroscopic CC ligament augmentation with a flip button/polyethylene belt repair is an efficient method to treat acute type III and V AC joint dislocations which should be popularized. IV.

  2. Arthroscopically Assisted Reconstruction of Acute Acromioclavicular Joint Dislocations: Anatomic AC Ligament Reconstruction With Protective Internal Bracing—The “AC-RecoBridge” Technique

    PubMed Central

    Izadpanah, Kaywan; Jaeger, Martin; Ogon, Peter; Südkamp, Norbert P.; Maier, Dirk

    2015-01-01

    An arthroscopically assisted technique for the treatment of acute acromioclavicular joint dislocations is presented. This pathology-based procedure aims to achieve anatomic healing of both the acromioclavicular ligament complex (ACLC) and the coracoclavicular ligaments. First, the acromioclavicular joint is reduced anatomically under macroscopic and radiologic control and temporarily transfixed with a K-wire. A single-channel technique using 2 suture tapes provides secure coracoclavicular stabilization. The key step of the procedure consists of the anatomic repair of the ACLC (“AC-Reco”). Basically, we have observed 4 patterns of injury: clavicular-sided, acromial-sided, oblique, and midportion tears. Direct and/or transosseous ACLC repair is performed accordingly. Then, an X-configured acromioclavicular suture tape cerclage (“AC-Bridge”) is applied under arthroscopic assistance to limit horizontal clavicular translation to a physiological extent. The AC-Bridge follows the principle of internal bracing and protects healing of the ACLC repair. The AC-Bridge is tightened on top of the repair, creating an additional suture-bridge effect and promoting anatomic ACLC healing. We refer to this combined technique of anatomic ACLC repair and protective internal bracing as the “AC-RecoBridge.” A detailed stepwise description of the surgical technique, including indications, technical pearls and pitfalls, and potential complications, is given. PMID:26052493

  3. Double-button Fixation System for Management of Acute Acromioclavicular Joint Dislocation

    PubMed Central

    Torkaman, Ali; Bagherifard, Abolfazl; Mokhatri, Tahmineh; Haghighi, Mohammad Hossein Shabanpour; Monshizadeh, Siamak; Taraz, Hamid; Hasanvand, Amin

    2016-01-01

    Background: Surgical treatments for acromioclavicular (AC) joint dislocation present with some complications. The present study was designed to evaluate the double-button fixation system in the management of acute acromioclavicular joint dislocation. Methods: This cross sectional study, done between February 2011 to June 2014, consisted of 28 patients who underwent surgical management by the double-button fixation system for acute AC joint dislocation. Age, sex, injury mechanism, dominant hand, side with injury, length of follow up, time before surgery, shoulder and hand (DASH), constant and visual analogue scale (VAS) scores, and all complications of the cases during the follow up were recorded. Results: The mean age of patients was 33.23±6.7 years. Twenty four patients (85.71%) were male and four (14.28%) were female. The significant differences were observed between pre-operation VAS, constant shoulder scores and post-operation measurements. There were not any significant differences between right and left coracoclavicular, but two cases of heterotrophic ossifications were recorded. The mean follow-up time was 16.17±4.38 months. Conclusion: According to the results, the double-button fixation system for management of acute acromioclavicular joint dislocation has suitable results and minimal damage to the soft tissues surrounding the coracoclavicular ligaments. PMID:26894217

  4. Combined acromioclavicular joint dislocation and coracoid avulsion in an adult.

    PubMed

    Naik, Monappa; Tripathy, Sujit Kumar; Goyal, Saumitra; Rao, Sarath K

    2015-05-20

    Avulsion fracture of coracoid process with acromioclavicular joint dislocation is extremely rare. We report a case of coracoid avulsion with acromioclavicular disruption in a 24-year-old man who sustained injuries in a road traffic accident. Although acromioclavicular (AC) dislocation was obvious from an initial radiograph, coracoid avulsion was picked up in a CT scan. Open reduction and internal fixations of the coracoid with a 4 mm cannulated screw, an AC joint with two K-wires and an anchor suture, resulted in rapid recovery. The patient had complete range of shoulder movements at the end of 3 months and he resumed his professional activities. After 1 year, he had normal shoulder movement without any functional limitations. 2015 BMJ Publishing Group Ltd.

  5. Combined acromioclavicular joint dislocation and coracoid avulsion in an adult

    PubMed Central

    Naik, Monappa; Tripathy, Sujit Kumar; Goyal, Saumitra; Rao, Sarath K

    2015-01-01

    Avulsion fracture of coracoid process with acromioclavicular joint dislocation is extremely rare. We report a case of coracoid avulsion with acromioclavicular disruption in a 24-year-old man who sustained injuries in a road traffic accident. Although acromioclavicular (AC) dislocation was obvious from an initial radiograph, coracoid avulsion was picked up in a CT scan. Open reduction and internal fixations of the coracoid with a 4 mm cannulated screw, an AC joint with two K-wires and an anchor suture, resulted in rapid recovery. The patient had complete range of shoulder movements at the end of 3 months and he resumed his professional activities. After 1 year, he had normal shoulder movement without any functional limitations. PMID:25994429

  6. [Classification and Treatment of Sacroiliac Joint Dislocation].

    PubMed

    Tan, Zhen; Huang, Zhong; Li, Liang; Meng, Wei-Kun; Liu, Lei; Zhang, Hui; Wang, Guang-Lin; Huang, Fu-Guo

    2017-09-01

    To develop a renewed classification and treatment regimen for sacroiliac joint dislocation. According to the direction of dislocation of sacroiliac joint,combined iliac,sacral fractures,and fracture morphology,sacroiliac joint dislocation was classified into 4 types. Type Ⅰ (sacroiliac anterior dislocation): main fracture fragments of posterior iliac wing dislocated in front of sacroiliac joint. Type Ⅱ (sacroiliac posterior dislocation): main fracture fragments of posterior iliac wing dislocated in posterior of sacroiliac joint. Type Ⅲ (Crescent fracturedislocation of the sacroiliac joint): upward dislocation of posterior iliac wing with oblique fracture through posterior iliac wing. Type ⅢA: a large crescent fragment and dislocation comprises no more than onethird of sacroiliac joint,which is typically inferior. Type ⅢB: intermediatesize crescent fragment and dislocation comprises between one and twothirds of joint. Type ⅢC: a small crescent fragment where dislocation comprises most,but not the entire joint. Different treatment regimens were selected for different types of fractures. Treatment for type Ⅰ sacroiliac joint dislocation: anterior iliac fossa approach pry stripping reset; sacroiliac joint fixed with sacroiliac screw through percutaneous. Treatment for type Ⅱ sacroiliac joint dislocation: posterior sacroiliac joint posterior approach; sacroiliac joint fixed with sacroiliac screw under computer guidance. Treatment for type ⅢA and ⅢB sacroiliac joint dislocation: posterior sacroiliac joint approach; sacroiliac joint fixed with reconstruction plate. Treatment for type ⅢC sacroiliac joint dislocation: sacroiliac joint closed reduction; sacroiliac joint fixed with sacroiliac screw through percutaneous. Treatment for type Ⅳ sacroiliac joint dislocation: posterior approach; sacroiliac joint fixed with spinal pelvic fixation. Results of 24 to 72 months patient follow-up (mean 34.5 months): 100% survival,100% wound healing,and 100

  7. Temporomandibular joint dislocation

    PubMed Central

    Sharma, Naresh Kumar; Singh, Akhilesh Kumar; Pandey, Arun; Verma, Vishal; Singh, Shreya

    2015-01-01

    Temporomandibular joint (TMJ) dislocation is an uncommon but debilitating condition of the facial skeleton. The condition may be acute or chronic. Acute TMJ dislocation is common in clinical practice and can be managed easily with manual reduction. Chronic recurrent TMJ dislocation is a challenging situation to manage. In this article, we discuss the comprehensive review of the different treatment modalities in managing TMJ dislocation. PMID:26668447

  8. Acromioclavicular joint dislocations: coracoclavicular reconstruction with and without additional direct acromioclavicular repair.

    PubMed

    Weiser, Lukas; Nüchtern, Jakob V; Sellenschloh, Kay; Püschel, Klaus; Morlock, Michael M; Rueger, Johannes M; Hoffmann, Michael; Lehmann, Wolfgang; Großterlinden, Lars G

    2017-07-01

    To evaluate different stabilisation techniques for acromioclavicular (AC) joint separations, including direct AC repair, and to compare the properties of the stabilised and native joints. An established in vitro testing model for the AC joint was used to analyse joint stability after surgical reconstruction [double TightRope (DTR), DTR with AC repair (DTR + AC), single TR with AC repair (TR + AC), and PDS sling with AC repair (PDS + AC)]. Twenty-four human cadaveric shoulders were randomised by age into four testing groups. Joint stiffness was measured by applying an axial load during defined physiological ranges of motion. Similar tests were performed for the native joints, after dissecting the coracoclavicular and AC ligaments, and after surgical reconstruction. Cyclic loading was performed for 1000 cycles with 20-70 N and vertical load to failure determined after cyclic testing. Axial stiffness for all TR groups was significantly higher than for the native joint (DTR 38.94 N/mm, p = 0.005; DTR + AC 37.79 N/mm, p = 0.015; TR + AC 45.61 N/mm, p < 0.001 vs. native 26.05 N/mm). The axial stiffness of the PDS + AC group was similar to that of the native joint group (21.4 N/mm, n.s.). AC repair did not significantly influence rotational stiffness. Load to failure was similar and >600 N in all groups (n.s.). Reconstruction of AC dislocations with one or two TRs leads to stable results with a higher stiffness than the native joints. For the PDS + AC group, axial stiffness was similar to the native situation, although there might be a risk of elongation. Direct AC repair showed no significantly increased stability in comparison with reconstructions without direct AC repair. Thus, a direct AC repair seems to be dispensable in clinical practice, while TRs or PDS cerclages appear to provide sufficiently stable results.

  9. Open capsular and ligament reconstruction with semitendinosus hamstring autograft successfully controls superior and posterior translation for type V acromioclavicular joint dislocation.

    PubMed

    Garofalo, Raffaele; Ceccarelli, Enrico; Castagna, Alessandro; Calvisi, Vittorio; Flanagin, Brody; Conti, Marco; Krishnan, Sumant G

    2017-07-01

    Appropriate surgical management for type V complete acromioclavicular (AC) joint dislocation remains controversial. The purpose of this paper is to retrospectively report the clinical and radiographic outcomes of an open surgical technique consisting for AC joint ligamentous and capsular reconstruction using autologous hamstring tendon grafts and semi-permanent sutures. Between January 2005 and December 2011, 32 consecutive patients with symptomatic type V complete AC joint dislocation underwent surgical treatment using the same technique. The median time from injury to surgery was 45 days (range 24-90). The average median postoperative clinical and radiographic follow-up time was 30 months (range 24-33). Clinical outcomes measures included the ASES score, the visual analog score (VAS), and subjective patient satisfaction score. Minimum follow-up was 2 years. ASES score increased from a median of 38.2 ± 6.2 preoperative to 92.1 ± 4.7 postoperatively (p ≤ 0.05). The median VAS score improved from 62 mm (range 45-100 mm) preoperatively to 8 mm (range 0-20 mm) at final follow-up (p ≤ 0.05). No patient experienced pain or discomfort with either direct palpation of the AC joint or with cross-body adduction. Final radiographs demonstrated symmetric AC joint contour in 25/32 (78%) patients. Seven patients (22%) radiographically demonstrated superior translation of the distal clavicle relative to the superior margin of the acromion but less than 50% of the clavicular width. 30/32 patients (93%) were able to return to their pre-injury level of work and sports activities. This novel surgical technique using a free graft and braided suture for simultaneous coracoclavicular ligament and AC joint capsular reconstruction successfully controls superior and posterior translations after type V AC joint dislocation and minimizes the incidence of persistent postoperative AC joint subluxation. Retrospective case series, Level IV.

  10. Surgical treatment of acute type V acromioclavicular joint dislocations in professional athletes: an anatomic ligament reconstruction with synthetic implant augmentation.

    PubMed

    Triantafyllopoulos, Ioannis K; Lampropoulou-Adamidou, Kalliopi; Schizas, Nikitas P; Karadimas, Eleftherios V

    2017-12-01

    Most acromioclavicular (AC) joint injuries occur in men in their third decade of life during high-speed or high-impact body contact sports. The management of acute complete AC joint dislocation is surgical. Current surgical techniques include anatomic reconstruction of the main restraints of the AC joint and aim to improve functional outcomes and to reduce the complication rate. We present 10 cases of acute type V AC joint dislocation in professional athletes treated surgically with anatomic reconstruction of the coracoclavicular and AC ligaments and augmentation with the use of a synthetic polyester tape. The minimum follow-up of the patients was 2 years (mean, 48 months; range, 24-86 months). The postoperative functional outcome was assessed at 1 year and 2 years using the Constant-Murley, American Shoulder and Elbow Surgeons, and modified University of California-Los Angeles scoring systems. In all cases, the postoperative scores were significantly improved (P < .005 in all comparisons with the preoperative scores), and all patients returned to their preinjury high level of activity 6 months postoperatively. Radiographs at 1 month and 6 months revealed the maintenance of reduction. There were no complications. According to the results of our series of patients, demanding cases of acute AC joint dislocation Rockwood type V, in professional athletes, require anatomic fixation of both coracoclavicular and AC ligaments for return to sports as soon as possible and at the preinjury level of performance. Copyright © 2017 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Elsevier Inc. All rights reserved.

  11. Acromioclavicular Joint Dislocation with Ipsilateral Mid Third Clavicle, Mid Shaft Humerus and Coracoid Process Fracture - A Case Report.

    PubMed

    Sharma, Naveen; Mandloi, Avinash; Agrawal, Ashish; Singh, Shailendra

    2016-01-01

    The clavicle, humerus and acromioclavicular (AC) joint separately are very commonly involved in traumatic injuries around the shoulder. Acromioclavicular joint dislocation with distal clavicle fracture is a well recognized entity in clinical practice. AC joint dislocation with mid shaft clavicle fracture is uncommon and only few cases have been reported in literature. However, to the best of our knowledge, this is the first case report to describe an acromioclavicular dislocation with ipsilateral mid shaft clavicle, mid shaft humerus and coracoid process fracture. Fractures of the humerus and clavicle along with the acromioclavicular joint dislocation were fixed at the same setting. A 65-year-old male met with a high velocity road traffic accident. Plain radiographs showed displaced mid third clavicle fracture with acromioclavicular joint dislocation with mid shaft humerus fracture. Surgical fixation was planned for humerus with interlocking nail, clavicle with locking plate and acromioclavicular joint with reconstruction of coracoclavicular ligaments. Intraoperatively, coracoid process was found to have a comminuted fracture. The operative plan had to be changed on table as coracoclavicular fixation was not possible. So acromioclavicular joint fixation was done using tension band wiring and the coracoclavicular ligament was repaired using a 2-0 ethibond. The comminuted coracoid fracture was managed conservatively. K wires were removed at 6 weeks. Early mobilization was started. In acromioclavicular joint injuries, clavicle must be evaluated for any injury. Although it is more commonly associated with distal clavicle fractures, it can be associated with middle third clavicle fractures. As plain radiographs, AP view are most of the times insufficient for viewing integrity of coracoid process, either special views like Stryker notch or CT scan may help in diagnosing such concealed injuries. When associated with fractures of the humerus and clavicle, anatomical

  12. Surgical treatment of acute acromioclavicular joint dislocations: hook plate versus minimally invasive reconstruction.

    PubMed

    Metzlaff, S; Rosslenbroich, S; Forkel, P H; Schliemann, B; Arshad, H; Raschke, M; Petersen, W

    2016-06-01

    This study was performed to compare the clinical results of a minimally invasive technique for acute acromioclavicular (AC) joint dislocation repair with the traditional hook plate fixation. Forty-four patients with an acute (within 2 weeks after trauma) complete AC joint separation (35 male, nine female; median age 36.2 years, range 18-56) underwent surgical repair with either a minimally invasive AC joint repair or a conventional hook plate. Functional outcome was evaluated using the Constant-Murley Score (CMS), the TAFT score and the AC joint instability score (ACJI). Radiographic evaluation was performed with bilateral anterior-posterior (a.p.) stress and Alexander views. All patients were available after a median follow-up of 32 months (range 24-51). There were no significant differences in the mean CMS, Taft score and the ACJI between the two groups. The radiological assessment revealed no significant difference in the coracoclavicular distance. In both groups, a slight loss of reduction was observed. Periarticular ossification was seen in 11 patients of the minimally invasive AC joint repair and eight patients of the hook plate group but this did not affect the final outcome. Hook plates were removed after a median interval of 11.9 weeks (range 10-13). Good clinical results can be achieved with both minimally invasive AC joint repair and hook plate fixation. However, in the hook plate group a second operation is mandatory for plate removal. III.

  13. Help Desk Answers: Surgery vs conservative management for AC joint repair: How do the 2 compare?

    PubMed

    Matchin, Bruce; Yee, Bruce; Mott, Timothy

    2016-04-01

    When not considering the grade of acromioclavicular (AC) joint dislocation, both conservative and surgical management lead to positive outcomes, although surgically managed patients require more time out of work.

  14. Simultaneous dislocation of the metacarpophalangeal and interphalangeal joints of the thumb.

    PubMed

    Tabib, William; Sayegh, Samir

    2002-01-01

    Combined dislocation of the metacarpophalangeal and interphalangeal joints of the thumb is uncommon. We know of only four previously reported cases. We report a new case characterised by dorsal dislocation of both joints. Because of entrapment of the volar plate, open reduction at the interphalangeal joint was necessary. The metacarpophalangeal dislocation was treated by closed reduction. After three weeks of immobilisation, physiotherapy resulted in a satisfactory outcome. Even if the diagnosis of dislocation of the interphalangeal joint is obvious it would be easy to overlook a simultaneous dislocation of the metacarpophalangeal joint with serious consequences. Whole hand examination remains an essential rule.

  15. In-game Management of Common Joint Dislocations

    PubMed Central

    Skelley, Nathan W.; McCormick, Jeremy J.; Smith, Matthew V.

    2014-01-01

    Context: Sideline management of sports-related joint dislocations often places the treating medical professional in a challenging position. These injuries frequently require prompt evaluation, diagnosis, reduction, and postreduction management before they can be evaluated at a medical facility. Our objective is to review the mechanism, evaluation, reduction, and postreduction management of sports-related dislocations to the shoulder, elbow, finger, knee, patella, and ankle joints. Evidence Acquisition: A literature review was performed using the PubMed database to evaluate previous and current publications focused on joint dislocations. This review focused on articles published between 1980 and 2013. Study Design: Clinical review. Level of Evidence: Level 4. Results: The clinician should weigh the benefits and risks of on-field reduction based on their knowledge of the injury and the presence of associated injuries. Conclusion: When properly evaluated and diagnosed, most sports-related dislocations can be reduced and initially managed at the game. PMID:24790695

  16. Inter- and intraobserver reliability of the Rockwood classification in acute acromioclavicular joint dislocations.

    PubMed

    Schneider, M M; Balke, M; Koenen, P; Fröhlich, M; Wafaisade, A; Bouillon, B; Banerjee, M

    2016-07-01

    The reliability of the Rockwood classification, the gold standard for acute acromioclavicular (AC) joint separations, has not yet been tested. The purpose of this study was to investigate the reliability of visual and measured AC joint lesion grades according to the Rockwood classification. Four investigators (two shoulder specialists and two second-year residents) examined radiographs (bilateral panoramic stress and axial views) in 58 patients and graded the injury according to the Rockwood classification using the following sequence: (1) visual classification of the AC joint lesion, (2) digital measurement of the coracoclavicular distance (CCD) and the horizontal dislocation (HD) with Osirix Dicom Viewer (Pixmeo, Switzerland), (3) classification of the AC joint lesion according to the measurements and (4) repetition of (1) and (2) after repeated anonymization by an independent physician. Visual and measured Rockwood grades as well as the CCD and HD of every patient were documented, and a CC index was calculated (CCD injured/CCD healthy). All records were then used to evaluate intra- and interobserver reliability. The disagreement between visual and measured diagnosis ranged from 6.9 to 27.6 %. Interobserver reliability for visual diagnosis was good (0.72-0.74) and excellent (0.85-0.93) for measured Rockwood grades. Intraobserver reliability was good to excellent (0.67-0.93) for visual diagnosis and excellent for measured diagnosis (0.90-0.97). The correlations between measurements of the axial view varied from 0.68 to 0.98 (good to excellent) for interobserver reliability and from 0.90 to 0.97 (excellent) for intraobserver reliability. Bilateral panoramic stress and axial radiographs are reliable examinations for grading AC joint injuries according to Rockwood's classification. Clinicians of all experience levels can precisely classify AC joint lesions according to the Rockwood classification. We recommend to grade acute ACG lesions by performing a digital

  17. The relationship between chronic type III acromioclavicular joint dislocation and cervical spine pain

    PubMed Central

    2009-01-01

    Background This study was aimed at evaluating whether or not patients with chronic type III acromioclavicular dislocation develop cervical spine pain and degenerative changes more frequently than normal subjects. Methods The cervical spine of 34 patients with chronic type III AC dislocation was radiographically evaluated. Osteophytosis presence was registered and the narrowing of the intervertebral disc and cervical lordosis were evaluated. Subjective cervical symptoms were investigated using the Northwick Park Neck Pain Questionnaire (NPQ). One-hundred healthy volunteers were recruited as a control group. Results The rate and distribution of osteophytosis and narrowed intervertebral disc were similar in both of the groups. Patients with chronic AC dislocation had a lower value of cervical lordosis. NPQ score was 17.3% in patients with AC separation (100% = the worst result) and 2.2% in the control group (p < 0.05). An inverse significant nonparametric correlation was found between the NPQ value and the lordosis degree in the AC dislocation group (p = 0.001) wheras results were not correlated (p = 0.27) in the control group. Conclusions Our study shows that chronic type III AC dislocation does not interfere with osteophytes formation or intervertebral disc narrowing, but that it may predispose cervical hypolordosis. The higher average NPQ values were observed in patients with chronic AC dislocation, especially in those that developed cervical hypolordosis. PMID:20015356

  18. Bilateral temporomandibular joint dislocation with locked mandibular impaction.

    PubMed

    Hynes, Sally L; Jansen, Leigh A; Brown, D Ross; Courtemanche, Douglas J; Boyle, James C

    2012-02-01

    Bilateral anterior temporomandibular joint dislocation is very rare, with only 2 reported cases published. In the present report, we describe a healthy 25-year-old man from Haida Gwaii, in British Columbia, Canada, who was transferred to our tertiary trauma center with life-threatening complications of a bilateral anterior temporomandibular joint dislocation with locked mandibular impaction. Copyright © 2012 American Association of Oral and Maxillofacial Surgeons. Published by Elsevier Inc. All rights reserved.

  19. [Trigeminal motor paralysis and dislocation of the temporo-mandibular joints].

    PubMed

    Ohkawa, S; Yoshida, T; Ohsumi, Y; Tabuchi, M

    1996-07-01

    A 64-year-old woman with diabetes mellitus was admitted to our hospital with left hemiparesis of sudden onset. A brain MRI demonstrated a cerebral infarction in the ventral part of the right lower pons. When left hemiparesis worsened, she had dislocation of the temporo-mandibular joints repeatedly. Then, her lower jaw deviated to the right when she opened her mouth. Also, there was decreased contraction of the right masseter when she clenched her teeth. These findings suggest that there was trigeminal motor paralysis on the right side resulting from involvement of the intrapontine trigeminal motor nerve. She has no history of dislocation of the temporo-mandibular joints. An X-ray film showed that the temporo-mandibular joints were intact. Thus, it is possible that deviation of the lower jaw was the cause of this dislocation. We suspect that dislocation of the temporo-mandibular joints may occur as a complication of unilateral trigeminal motor paralysis. This has not been reported to our knowledge.

  20. [A new type sternoclavicular hook plate for unstable sternoclavicular joint dislocation and fracture].

    PubMed

    Zhang, Chuan-Yi; Lin, Lie; Liang, Jun-Bo; Wang, Bin; Chen, Guo-Fu; Chen, Hai-Xiao

    2016-11-25

    To evaluate the therapeutic effect of a new type sternoclavicular hook plate fixation in treating unstable sternoclavicular joint dislocation and fracture. From June 2011 to December 2013, 32 patients with sternoclavicular joint dislocation and fracture were treated with a new type sternoclavicular hook plate fixation, including 24 males and 8 females with an average age of 42 years ranging from 25 to 76 years;12 patients were anterior dislocation, 5 pations were posterior dislocation, 10 patients were internal extremity of clavicle fracture and 5 patients were sternoclavicular joint dislocation combined with fracture. The anterior fracture dislocation of the sternoclavicular joint adopted standard sternoclavicular joint hook plate, and the posterior dislocation was at the distal end of the hook of the steel plate, that is, the front part of the handle of the breast was added with a nut and a gasket to prevent the re-dislocation after operation. The results were evaluated according to Rockwood score. No complication happened in all patients. X-ray and CT showed that the dislocation and fracture of the sternoclavicular joint was well reduced and the plate was on right position. All patients were followed up for 6 to 24 months with an average of 10 months. At 6 to 3 months after operation, the fracture was healing without re-dislocation of the sternoclavicular joint, the medial end of the clavicle anatomical structure were restored, functional satisfaction, in which 9 patients with the swelling around sternoclavicular joint, but no pain and other symptoms. The total Rockwood score was 12.78±1.43; the results were excellent in 24 cases, good in 8 cases. The use of the new type of locking hook plate for the treatment of unstable fracture of the sternoclavicular joint, internal fixation is reliable, high security, easy to operate, to provide a reliable method for the treatment of such trauma.

  1. A retrospective comparative study of arthroscopic fixation in acute Rockwood type IV acromioclavicular joint dislocation: single versus double paired Endobutton technique.

    PubMed

    Xu, Jian; Liu, Haifeng; Lu, Wei; Li, Dingfu; Zhu, Weimin; Ouyang, Kan; Wu, Bing; Peng, Liangquan; Wang, Daping

    2018-05-24

    Rockwood type IV acromioclavicular joint (ACJ) dislocation is a trauma usually needs surgical treatment. Paired EndoButton technique (PET) is used in treating such condition. However, the effect of using different types of PET (single versus double PET) for fixation remains controversial. This study aims to evaluate and compare the efficacy of single and double PET and to provide a suitable option for the surgeons. We retrospectively reviewed the charts of patients with acute Rockwood type IV ACJ dislocation who had undergone arthroscopic fixation using single or double PET fixation between March 2009 and March 2015. Seventy-eight consecutive patients identified from chart review were picked and were divided into the single and double PET group with 39 cases in each group. The indexes of visual analog scale score (VAS) for pain, the radiographs of the affected shoulder at different time points of the follow-up, the time of return to activities and sports, the constant functional score, and the Karlsson acromioclavicular joint (ACJ) score, were assessed in a minimum of 2 years postoperation. The average coracoclavicular (CC) and acromioclavicular (AC) distances of the affected joints in the double PET group were significantly smaller than those of the single PET group 2 years postoperation (P < 0.05). The average AC and CC distances in the healthy shoulder joints were significantly smaller than those of the affected joints in the single PET group (P < 0.05); however, these values were not significantly different from those of the affected joints in the double PET group (P > 0.05). The mean VAS pain score was not significantly different, while significant difference was found for the number and times of cases return to activities and sports, constant functional score, and Karlsson ACJ score (P < 0.05) between the two groups. Therefore, the double PET group has better outcome than the single PET group. Complications including redislocation, button

  2. Clinical outcomes of the Cadenat procedure in the treatment of acromioclavicular joint dislocations.

    PubMed

    Moriyama, Hiroaki; Gotoh, Masafumi; Mitsui, Yasuhiro; Yoshikawa, Eiichirou; Uryu, Takuya; Okawa, Takahiro; Higuchi, Fujio; Shirahama, Masahiro; Shiba, Naoto

    2014-01-01

    We report our clinical experience using the modified Cadenat method to treat acromioclavicular joint dislocation, and discuss the usefulness of this method. This study examined 6 shoulders in 6 patients (5 males, 1 female) who were diagnosed with acromioclavicular joint dislocation and treated with the modified Cadenat method at our hospital. Average age at onset was 49.3 years (26-78 years), average time interval from injury until surgery was 263.8 days (10 to 1100 days), and the average follow-up period was 21.7 months (12 to 42 months). Post-operative assessment was performed using plain radiographs to determine shoulder joint dislocation rate and Japanese Orthopaedic Association (JOA) score. The average post-operative JOA score was 94.1 points (91 to 100 points). The acromioclavicular joint dislocation rate improved from 148.7% (72 to 236%) before surgery to 28.6% (0 to 60%) after surgery. Conservative treatment has been reported to achieve good outcomes in acromioclavicular joint dislocations. However, many patients also experience chronic pain or a sensation of fatigue upon putting the extremity in an elevated posture, and therefore ensuring the stability of the acromioclavicular joint is crucial for highly active patients. In this study, we treated acromioclavicular joint dislocations by the modified Cadenat method, and were able to achieve favorable outcomes.

  3. Uncovertebral joint injury in cervical facet dislocation: the headphones sign.

    PubMed

    Palmieri, Francesco; Cassar-Pullicino, Victor N; Dell'Atti, Claudia; Lalam, Radhesh K; Tins, Bernhard J; Tyrrell, Prudencia N M; McCall, Iain W

    2006-06-01

    The purpose of our study is to demonstrate the uncovertebral mal-alignment as a reliable indirect sign of cervical facet joint dislocation. We examined the uncovertebral axial plane alignment of 12 patients with unilateral and bilateral cervical facet joint dislocation (UCFJD and BCFJD, respectively), comparing its frequency to the reverse hamburger bun sign on CT and MR axial images. Of the seven cases with BCFJD, five clearly demonstrated the diagnostic reverse facet joint hamburger bun sign on CT and MR images, but in two cases this sign was not detectable. In the five cases with UCFJD, four demonstrated the reverse hamburger bun sign on both CT and MRI. In one case the reverse hamburger bun sign was not seen adequately with either image modality, but the facet dislocation was identified on sagittal imaging. The uncovertebral mal-alignment was detected in all 12 cases. Normally, the two components of the uncovertebral joint enjoy a concentric relationship that in the axial plane is reminiscent of the relationship of headphones with the wearer's head. We name this appearance the 'headphones' sign. Radiologists should be aware of the headphones sign as a reliable indicator of facet joint dislocation on axial imaging used in the assessment of cervical spine injuries.

  4. [Clinical applications of sternoclavicular hook plate for the treatment of sternoclavicular joint dislocation].

    PubMed

    Chen, Fang-Hu; Zhao, Xiao-Ping; Zheng, Wen-Biao; Zeng, Han-Bing; Ran, Bo; Huang, Hui; Wang, Hai-Bao

    2013-05-01

    To observe the clinical therapeutic effects of sternoclavicular hook plate for the treatment of sternoclavicular joint dislocation. From June 2010 to June 2012, 7 patients with sternoclavicular joint dislocation were treated with sternoclavicular hook plate fixation. Among the 7 patients, 5 patients were male and 2 patients were female, and the average age was 42.3 years, ranging from 38 to 54 years. The course of the disease ranged from 1 to 4 weeks. All the patients had trauma history. The clinical manifestations included: obvious swelling and pain of sternoclavicular joint, restricted shoulder joint activity. The sternoclavicular joint dislocation was proved by preoperative X-ray and CT. The postoperative curative effect was evaluated according to Rockwood scoring method. According to Rockwood scoring method, the excellent results obtained in 6 cases, good in 1. There were no complications such as internal fixation loosening or broken, second dislocation, pain in the sternoclavicular joint, and deformity. The function of shoulder joint was good, and the limb activity was free and no pain appeared. The sternoclavicular hook plate for the treatment of sternoclavicular joint dislocation has follow advantages: simple procedure, stable fixation, definite therapeutic effects.

  5. Acute acromioclavicular dislocation: a cheaper, easier and all-arthroscopic system. Is it effective in nowadays economical crisis?

    PubMed

    Sastre, Sergi; Dada, Michelle; Santos, Simon; Lozano, Lluis; Alemany, Xavier; Peidro, Lluis

    2015-03-01

    The objective of this manuscript is to show an effective, easier and cheaper way to reduce acute acromioclavicular (AC) dislocation type III and V (Rockwood classification). Numerous procedures have been described for surgical management of acromioclavicular joint disruption. Newest devices involve an arthroscopic technique that allows nonrigid anatomic fixation of the acromioclavicular joint. Arthroscopically assisted treatment of acute AC joint dislocation is advantageous because it provides good clinical results and few complications. It also allows reviewing glenohumeral associated lesions. This surgical technique requires no specific implants to achieve a correct AC reduction. Actually, economical advantages are very important factors to decide the use of determinate surgical techniques.

  6. Morphological changes in the cervical intervertebral foramen dimensions with unilateral facet joint dislocation.

    PubMed

    Ebraheim, Nabil A; Liu, Jiayong; Ramineni, Satheesh K; Liu, Xiaochen; Xie, Joe; Hartman, Ryan G; Goel, Vijay K

    2009-11-01

    Many investigators have conducted studies to determine the biomechanics, causes, complications and treatment of unilateral facet joint dislocation in the cervical spine. However, there is no quantitative data available on morphological changes in the intervertebral foramen of the cervical spine following unilateral facet joint dislocation. These data are important to understand the cause of neurological compromise following unilateral facet joint dislocation. Eight embalmed human cadaver cervical spine specimens ranging from level C1-T1 were used. The nerve roots of these specimens at C5-C6 level were marked by wrapping a 0.12mm diameter wire around them. Unilateral facet dislocation at C5-C6 level was simulated by serially sectioning the corresponding ligamentous structures. A CT scan of the specimens was obtained before and after the dislocation was simulated. A sagittal plane through the centre of the pedicle and facet joint was constructed and used for measurement. The height and area of the intervertebral foramen, the facet joint space, nerve root diameter and area, and vertebral alignment both before and after dislocation were evaluated. The intervertebral foramen area changed from 50.72+/-0.88mm(2) to 67.82+/-4.77mm(2) on the non-dislocated side and from 41.39+/-1.11mm(2) to 113.77+/-5.65mm(2) on the dislocated side. The foraminal heights changed from 9.02+/-0.30mm to 10.52+/-0.50mm on the non-dislocated side and 10.43+/-0.50mm to 17.04+/-0.96mm on the dislocated side. The facet space area in the sagittal plane changed from 6.80+/-0.80mm(2) to 40.02+/-1.40mm(2) on the non-dislocated side. The C-5 anterior displacement showed a great change from 0mm to 5.40+/-0.24mm on the non-dislocated side and from 0mm to 3.42+/-0.20mm on the dislocated side. Neither of the nerve roots on either side showed a significant change in size. The lack of change in nerve root area indicates that the associated nerve injury with unilateral facet joint dislocation is probably due

  7. Anterior fracture dislocation of the sacroiliac joint: A case report and literature review.

    PubMed

    Xiao, Jianlin; Wang, Yang; Zhang, Minglei; Jiang, Rui; Zhu, Tongtong; Liu, Guangyao; Zuo, Jianlin

    2017-08-09

    Publications describing the diagnosis and treatment of anterior dislocation of the sacroiliac joint are scarce. We report the case a 19-year-old female at 8 weeks' gestation who presented with anterior fracture dislocation of the right sacroiliac joint, posterior fracture dislocation of the left sacroiliac joint (crescent fracture), and incomplete abortion resulting from high energy trauma. Orthopedic surgery involved standard anterior sacroiliac joint plating using an ilioinguinal approach combined with a modified Stoppa approach. Three attempts at complete abortion failed. Complete abortion was eventually achieved by dilatation and curettage two weeks after orthopedic surgery. Our findings reveal a need to improve techniques for diagnosis and treatment of anterior fracture dislocation of the sacroiliac joint, so greater attention can be paid to the rapid and effective management of associated comorbidities, and those resulting from the initial trauma.

  8. [Dislocation of the PIP-Joint - Treatment of a common (ball)sports injury].

    PubMed

    Müller-Seubert, Wibke; Bührer, Gregor; Horch, Raymund E

    2017-09-01

    Background  Fractures or fracture dislocations of the proximal interphalangeal joint often occur during sports or accidents. Dislocations of the PIP-joint are the most common ligamentary injuries of the hand. As this kind of injury is so frequent, hand surgeons and other physicians should be aware of the correct treatment. Objectives  This paper summarises the most common injury patterns and the correct treatment of PIP-joint dislocations. Materials and Methods  This paper reviews the current literature and describes the standardised treatment of PIP-joint dislocations. Results  What is most important is that reposition is anatomically correct, and this should be controlled by X-ray examination. Depending on the instability and possible combination with other injuries (e. g. injury to the palmar plate), early functional physiotherapy of the joint or a short immobilisation period is indicated. Conclusions  Early functional treatment of the injured PIP-joint, initially using buddy taping, is important to restore PIP-joint movement and function. Depending on the injury, joint immobilisation using a K-wire may be indicated. Detailed informed consent is necessary to explain to the patient the severity of the injury and possible complications, such as chronic functional disorders or development of arthrosis. © Georg Thieme Verlag KG Stuttgart · New York.

  9. Outcomes of surgery for acromioclavicular joint dislocation using different angled hook plates: a prospective study.

    PubMed

    Xu, Ding; Luo, Peng; Chen, Jukun; Ji, Liefeng; Yin, Luxu; Wang, WeiKang; Zhu, Jiang

    2017-12-01

    Hook plate fixation is widely used to treat acromioclavicular joint dislocation. However, there are many post-operative complications affecting the effect of treatment. The aim of this study is to evaluate the efficacy of the clavicular hook plate with different hook angles as a method of treatment in AC joint dislocation, and to guide the clinical application of hook plate. We prospectively analysed 54 patients who were diagnosed with AC joint dislocation and treated with hook plate fixation by different hook angles. The patients were randomised into three groups: the -20° < AHP < 0° group, the 20° > AHP > 0° group and the 40° > AHP > 20° group. All patients were required to conform to regular follow-up post-operatively. Routine imaging to the shoulder was obtained to evaluate maintenance of the dislocation and the implant. Constant-Murley criteria were used to evaluate functional results. There were 19 patients in the -20° < AHP < 0° group, with one lost to follow-up, 22 patients in the 20° > AHP > 0° group, with two male patients lost to follow-up, and one female patient excluded because of no follow-up consent, and 19 patients in the 40° > AHP > 20° group, with one female and one male patient lost to follow-up. The Constant score was 61.8 ± 12.8, 74.7 ± 9.2 and 70.7 ± 9.4 before implant removal, and 78.8 ± 8.3, 87.1 ± 6.4 and 85.0 ± 6.1 after implant removal in the -20° < AHP < 0°, 20° > AHP > 0° and 40° > AHP > 20° groups, respectively. The functional results of the 20° > AHP > 0° and 40° > AHP > 20° groups were significantly better than the -20° < AHP < 0° group (P < 0.05), but the functional results of the 20° > AHP > 0° and 40° > AHP > 20° groups were not statistically significant. The CCD was 98.1 ± 4.8%, 107.5 ± 5.1% and 105.5 ± 4.1% before implant removal, and 98.8 ± 4.6%, 108.3 ± 4.8% and 107.2 ± 3.3% after implant removal in the

  10. Radiographic Shape of Foot With Second Metatarsophalangeal Joint Dislocation Associated With Hallux Valgus.

    PubMed

    Kokubo, Tetsuro; Hashimoto, Takeshi; Suda, Yasunori; Waseda, Akeo; Ikezawa, Hiroko

    2017-12-01

    Second metatarsophalangeal (MTP) joint dislocation is associated with hallux valgus, and the treatment of complete dislocation can be difficult. The purpose of this study was to radiographically clarify the characteristic foot shape in the presence of second MTP joint dislocation. Weight-bearing foot radiographs of the 268 patients (358 feet) with hallux valgus were examined. They were divided into 2 groups: those with second MTP joint dislocation (study group = 179 feet) and those without dislocation (control group = 179 feet). Parameters measured included the hallux valgus angle (HVA), first-second intermetatarsal angle (IMA), second MTP joint angle, hallux interphalangeal angle (IPA), second metatarsal protrusion distance (MPD), metatarsus adductus angle (MAA), and the second metatarsal declination angle (2MDA). Furthermore, the dislocation group was divided into 3 subgroups according to second toe deviation direction: group M (medial type), group N (neutral type), and group L (lateral type). The IPA and the 2MDA were significantly greater in the study group than in the control group. By multiple comparison analysis, the IMA was greatest in group M and smallest in group L. The IPA was smaller and 2MDA greater in group N than in group L. The HVA and MAA in group L were greatest, and MPD in group L was smallest. The patients with second MTP joint dislocation associated with hallux valgus had greater hallux interphalangeal joint varus and a second metatarsal more inclined than with hallux valgus alone. The second toe deviated in a different direction according to the foot shape. Level III, retrospective comparative study.

  11. Injury patterns of the acromioclavicular ligament complex in acute acromioclavicular joint dislocations: a cross-sectional, fundamental study.

    PubMed

    Maier, Dirk; Jaeger, Martin; Reising, Kilian; Feucht, Matthias J; Südkamp, Norbert P; Izadpanah, Kaywan

    2016-09-06

    Horizontal instability impairs clinical outcome following acute acromioclavicular joint (ACJ) reconstruction and may be caused by insufficient healing of the superior acromioclavicular ligament complex (ACLC). However, characteristics of acute ACLC injuries are poorly understood so far. Purposes of this study were to identify different ACLC tear types, assess type-specific prevalence and determine influencing cofactors. This prospective, cross-sectional study comprised 65 patients with acute-traumatic Rockwood-5 (n = 57) and Rockwood-4 (n = 8) injuries treated operatively by means of mini-open ACJ reduction and hook plate stabilization. Mean age at surgery was 38.2 years (range, 19-57 years). Standardized pre- and intraoperative evaluation included assessment of ACLC tear patterns and cofactors related to the articular disc, the deltoid-trapezoidal (DT) fascia and bony ACJ morphology. Articular disc size was quantified as 0 = absent, 1 = remnant, 2 = meniscoid and 3 = complete. All patients showed complete ruptures of the superior ACLC, which could be assigned to four different tear patterns. Clavicular-sided (AC-1) tears were observed in 46/65 (70.8 %), oblique (AC-2) tears in 12/65 (18.5 %), midportion (AC-3) tears in 3/65 (4.6 %) and acromial-sided (AC-4) tears in 4/65 (6.1 %) of cases. Articular disc size manifestation was significantly (P < .001) more pronounced in patients with AC-1 tears (1.89 ± 0.57) compared to patients with AC-2 tears (0.67 ± 0.89). Other cofactors did not influence ACLC tear patterns. ACLC dislocation with incarceration caused mechanical impediment to anatomical ACJ reduction in 14/65 (21.5 %) of cases including all Rockwood-4 dislocations. Avulsion "in continuity" was a consistent mode of failure of the DT fascia. Type-specific operative strategies enabled anatomical ACLC repair of all observed tear types. Acute ACLC injuries follow distinct tear patterns. There exist clavicular-sided (AC-1

  12. Closed reduction of a rare type III dislocation of the first metatarsophalangeal joint.

    PubMed

    Tondera, E K; Baker, C C

    1996-09-01

    To discuss a rare Type III dislocation of the first metatarsophalangeal (MP) joint, without fracture, that used a closed reduction technique for correction. A 43-yr-old man suffered from an acute severe dislocation of his great toe as the result of acute forceful motion applied to the toe as his foot was depressed onto a brake pedal to avoid a motor vehicle accident. Physical examination and X-rays revealed the dislocation, muscle spasm, edema and severely restricted range of motion. The dislocation was corrected using a closed reduction technique, in this case a chiropractic manipulation. Fourteen months after reduction, the joint was intact, muscle strength was graded +5 normal, ranges of motion were within normal limits and no crepitation was noted. X-rays revealed normal intact joint congruency. The patient experienced full weight bearing, range of motion and function of the joint. Although a Type III dislocation of the great toe has only once been cited briefly in the literature, this classification carries a recommended surgical treatment protocol for correction. No literature describes a closed reduction of a Type III dislocation as described in this case report. It is apparent that a closed reduction technique using a chiropractic manipulation may be considered a valid alternative correction technique for Type III dislocations of the great toe.

  13. Dislocation of temporo-mandibular joint - an uncommon circumstance of occurrence: vaginal delivery.

    PubMed

    El Bouazzaoui, Abderrahim; Labib, Smael; Derkaoui, Ali; Adnane Berdai, Mohammed; Bendadi, Azzeddine; Harandou, Mustapha

    2010-06-25

    Dislocation of temporo-mandibular joint (TMJ) is an infrequent disease but still spectacular. This disease consists of a permanent, to some extent complete disruption of the temporo-mandibular joint. These dislocations often occur in a context of yawning, and less frequently after a burst of laughing or relatively mild facial trauma (slap, punch on the chin). We report a case of TMJ occurring in an uncommon circumstance: vaginal delivery. A woman aged 24-years with no special past medical history; primipara was admitted in the Department of Maternity of the University Hospital Hassan II of Fez for an imminent delivery of a twin pregnancy. Ten minutes after admission, the patient delivered vaginally with episiotomy. She gave birth to twins weighing 2800 g and 2400 g. During labour, and due to efforts of crying, the patient developed a sudden and immediate loss of function of the temporo-mandibular joint, with difficulty of speaking, the mouth permanently opened and with the chin lowered and thrown forward. The examination found an empty glenoid fossa of the temporo-mandibular joint in both sides. The diagnosis of dislocation of the TMJ was established. A CT scan of facial bones was done, objectifying a bilateral dislocation of TMJ. The reduction of this dislocation was performed in the operating room under sedation.

  14. Evaluation of the mechanism and principles of management of temporomandibular joint dislocation. Systematic review of literature and a proposed new classification of temporomandibular joint dislocation.

    PubMed

    Akinbami, Babatunde O

    2011-06-15

    Virtually all the articles in literature addressed only a specific type of dislocation. The aim of this review was to project a comprehensive understanding of the pathologic processes and management of all types of dislodgement of the head of the mandibular condyle from its normal position in the glenoid fossa. In addition, a new classification of temporomandibular joint dislocation was also proposed. A thorough computer literature search was done using the Medline, Cochrane library and Embase database. Key words like temporo-mandibular joint dislocation were used for the search. Additional manual search was done by going through published home-based and foreign articles. Case reports/series, and original articles that documented the type of dislocation, number of cases treated in the series and original articles. Treatment done and outcome of treatment were included in the study. A total of 128 articles were reviewed out which 79 were found relevant. Of these, 26 were case reports, 17 were case series and 36 were original articles. 79 cases were acute dislocations, 35 cases were chronic protracted TMJ dislocations and 311 cases were chronic recurrent TMJ dislocations. Etiology was predominantly trauma in 60% of cases and other causes contributed about 40%. Of all the cases reviewed, only 4 were unilateral dislocation. Various treatment modalities are outlined in this report as indicated for each type of dislocation. The more complex and invasive method of treatment may not necessarily offer the best option and outcome of treatment, therefore conservative approaches should be exhausted and utilized appropriately before adopting the more invasive surgical techniques.

  15. An unusual variety of simultaneous fracture dislocation pattern: medial swivel dislocation of talonavicular joint with displaced fractures of the fourth and fifth metatarsals.

    PubMed

    Inal, Sermet; Inal, Canan

    2013-01-01

    In published studies, a very rare, special type of Chopart dislocation termed a swivel dislocation has been reported. This injury is characterized by dislocation of the talonavicular joint, but the calcaneocuboid joint remains intact. The foot creates a typical rotational movement without inversion or eversion. The axis of rotation is the interosseous talocalcaneal ligament, which remains intact. We report the case of an 18-year-old male who had experienced a medial swivel dislocation of the talonavicular joint associated with displaced fractures of the fourth and fifth metatarsals. The occurrence, features, and method of treatment of this rare injury are presented. Copyright © 2013 American College of Foot and Ankle Surgeons. Published by Elsevier Inc. All rights reserved.

  16. Evaluation of the mechanism and principles of management of temporomandibular joint dislocation. Systematic review of literature and a proposed new classification of temporomandibular joint dislocation

    PubMed Central

    2011-01-01

    Background Virtually all the articles in literature addressed only a specific type of dislocation. The aim of this review was to project a comprehensive understanding of the pathologic processes and management of all types of dislodgement of the head of the mandibular condyle from its normal position in the glenoid fossa. In addition, a new classification of temporomandibular joint dislocation was also proposed. Method and materials A thorough computer literature search was done using the Medline, Cochrane library and Embase database. Key words like temporo-mandibular joint dislocation were used for the search. Additional manual search was done by going through published home-based and foreign articles. Case reports/series, and original articles that documented the type of dislocation, number of cases treated in the series and original articles. Treatment done and outcome of treatment were included in the study. Result A total of 128 articles were reviewed out which 79 were found relevant. Of these, 26 were case reports, 17 were case series and 36 were original articles. 79 cases were acute dislocations, 35 cases were chronic protracted TMJ dislocations and 311 cases were chronic recurrent TMJ dislocations. Etiology was predominantly trauma in 60% of cases and other causes contributed about 40%. Of all the cases reviewed, only 4 were unilateral dislocation. Various treatment modalities are outlined in this report as indicated for each type of dislocation. Conclusion The more complex and invasive method of treatment may not necessarily offer the best option and outcome of treatment, therefore conservative approaches should be exhausted and utilized appropriately before adopting the more invasive surgical techniques. PMID:21676208

  17. Transarticular fixation by hook plate versus coracoclavicular stabilization by single multistrand titanium cable for acute Rockwood grade-V acromioclavicular joint dislocation: a case-control study.

    PubMed

    Gao, You-Shui; Zhang, Yue-Lei; Ai, Zi-Sheng; Sun, Yu-Qiang; Zhang, Chang-Qing; Zhang, Wei

    2015-11-19

    Hook plate (HP) is popularly used for acute and severely displaced acromioclavicular (AC) dislocations. However, subacromial impingement and acromion osteolysis induced by transarticular fixation are notorious. The current case-control study was to compare transarticular fixation by HP to coracoclavicular (CC) stabilization by single multistrand titanium cable (MSTC). Between January 2006 and August 2009, 24 patients with acute AC dislocations were surgically treated by open reduction and transarticular fixation with HP. These patients were matched to a series of 24 patients, who were managed by CC stabilization with MSTC in the same period. All AC dislocations were graded as Rockwood type V. Implant was removed 8-12 months after the primary operation in all patients, and 12 months at least were needed to assess the maintenance of AC joint. Functional results were evaluated before implant removal as well as in the last follow-up based on Constant-Murley criteria. There were no differences of demographic data including age, dominant gender and side, injury-to-surgery interval, operation time and follow-up period. In terms of functionality, Constant score was 95.8 ± 4.1 in MSTC group, while 76.7 ± 8.0 in HP group before implant removal (P < 0.001). In detail, MSTC was superior to HP in pain, ROM and activities. Constant score was significantly improved to 86.1 ± 5.7 after hardware removal for patients in HP (P < 0.001). Degenerative change of acromioclavicular joint presented in 16 patients (66.7%) in patients treated by HP, while it was found in only 3 patients (12.5%) treated by MSTC (P < 0.001). MSTC is superior to HP for the treatment of Rockwood type-V acromioclavicular dislocation both before and after removal of the implant. Hardware removal is of great benefits for functional improvement in patients treated by HP.

  18. Simultaneous Middle Third Clavicle Fracture and Type 3 Acromioclavicular Joint Dislocation; A Case Report

    PubMed Central

    Solooki, Saeed; Azad, Ali

    2014-01-01

    Simultaneous middle third clavicle fracture and acromioclavicular joint dislocation is a rare combination injury, as a result of high-energy trauma. We report a patient with a middle third clavicle fracture and ipsilateral grade three-acromioclavicular joint dislocation, which is a rare combination. The patient wanted to get back to work as soon as possible, so the fracture was fixed with reconstruction plate after open reduction and plate contouring; and acromioclavicular joint dislocation was reduced and fixed with two full threaded cancellous screws. One screw was inserted through the plate to the coracoid process. Clinical and radiographic finding revealed complete union of clavicle fracture and anatomical reduction of acromioclavicular joint with pain free full joint range of motion one year after operation. PMID:25207318

  19. [Experimental study of dislocations of the scapulohumeral joint].

    PubMed

    Gagey, O; Gagey, N; Boisrenoult, P; Hue, E; Mazas, F

    1993-01-01

    One may produce easily an experimental dislocation (anterior or erecta) of the scapulohumeral joint. The authors discuss, the experimental model then they describe the anatomical lesion produced through the experimental dislocation of 32 shoulders and the correlation observed after RMI assessment of 24 recurrent dislocations. The tear of the inferior glenohumeral ligament is constant, in 20 per cent of the cases the tear lies on the anterior aspect of the glenoid, in the other cases the tear was found on its humeral side. Whatever the situation of the tear of the inferior glenohumeral ligament, the lesion of the labrum was constant. The erecta dislocation was produced with the same movement but with a particular tear of the glenohumeral ligament: the tear was longitudinal. The experimental dislocation needs, in 7 or 8 cases, a desinsertion of the deep aspect of the rotator cuff. The Hill Sachs lesion occurs when the humerus falls along the chest wall after the dislocation. In 50 per cent of the patients, MRI shows modifications of the cuff which are compatible with our results. Hills Sachs lesions appear to be constant after MRI examination.

  20. A Case of Acromioclavicular Joint Dislocation Associated with Coracoid Process Fracture.

    PubMed

    Nakamura, Yosuke; Gotoh, Masafumi; Mitsui, Yasuhiro; Shirachi, Isao; Yoshikawa, Eiichiro; Uryu, Takuya; Murakami, Hidetaka; Okawa, Takahiro; Higuchi, Fujio; Shiba, Naoto

    2015-01-01

    Rupture of any two or more parts of the superior shoulder suspensory complex (SSSC) including the distal clavicle, acromion, coracoid process, glenoid cavity of the scapula, acromioclavicular ligament, and coracoclavicular ligament is associated with shoulder girdle instability and is an indication for surgery. Here we report a case of acromioclavicular joint dislocation associated with coracoid process fracture. A 48-year-old man sustained a hard blow to the left shoulder from a fall, and simple radiography detected a coracoid process fracture and acromioclavicular joint dislocation. The injury consisted of a rupture of two parts of the SSSC. For the coracoid process fracture, osteosynthesis was performed using hollow cancellous bone screws. For the acromioclavicular joint dislocation, hook plate fixation and the modified Neviaser's procedure were performed. The bone healed well 5 months after surgery, at which time the screws were removed. At 18 months after initial surgery, the coracoid process fracture had healed with a 10% rate of dislocation on radiography, and the patient currently has no problem performing daily activities, no range of motion limitations, and a Japanese Orthopaedic Association scale score of 93.

  1. Temporo-mandibular joint dislocation: an unusual complication of transoesophageal echocardiography.

    PubMed

    Anantharam, Brijesh; Chahal, Navtej; Stephens, Nigel; Senior, Roxy

    2010-03-01

    Temporo-mandibular joint (TMJ) dislocation is an unusual complication of transoesophageal echocardiography (TEE). We report a rare case of bilateral TMJ dislocation in an 84-year-old man prior to DC cardioversion (DCCV) for atrial flutter. Shortly after TEE and DCCV, the patient complained of bilateral facial pain. An orthopantomogram revealed bilateral TMJ dislocation. A closed reduction was performed by maxillo-facial surgeons under intravenous anaesthesia. Although very uncommon, the physician should be aware of the complication and its management.

  2. A modified surgical technique for reconstruction of an acute acromioclavicular joint dislocation

    PubMed Central

    Marchie, Anthony; Kumar, Arun; Catre, Melanio

    2009-01-01

    We report a modified surgical technique for reconstruction of coracoclavicular and acromioclavicular ligaments after acute dislocation of acromioclavicular joint using suture anchors. We have repaired 3 consecutive type III acromioclavicular dislocations with good results. This technique is simple and safe and allows anatomical reconstruction of the ligaments in acute dislocations. PMID:20671868

  3. Effects of hook plate on shoulder function after treatment of acromioclavicular joint dislocation.

    PubMed

    Chen, Chang-Hong; Dong, Qi-Rong; Zhou, Rong-Kui; Zhen, Hua-Qing; Jiao, Ya-Jun

    2014-01-01

    Internal fixation with hook plate has been used to treat acromioclavicular joint dislocation. This study aims to evaluate the effect of its use on shoulder function, to further analyze the contributing factors, and provide a basis for selection and design of improved internal fixation treatment of the acromioclavicular joint dislocation in the future. A retrospective analysis was performed on patients treated with a hook plate for acromioclavicular joint dislocation in our hospital from January 2010 to February 2013. There were 33 cases in total, including 25 males and 8 females, with mean age of 48.27 ± 8.7 years. There were 29 cases of Rockwood type III acromioclavicular dislocation, 4 cases of type V. The Constant-Murley shoulder function scoring system was used to evaluate the shoulder function recovery status after surgery. Anteroposterior shoulder X-ray was used to assess the position of the hook plate, status of acromioclavicular joint reduction and the occurrence of postoperative complications. According to the Constant-Murley shoulder function scoring system, the average scores were 78 ± 6 points 8 to 12 months after the surgery and before the removal of the hook plate, the average scores were 89 ± 5 minutes two months after the removal of hook plate. Postoperative X-ray imaging showed osteolysis in 10 cases (30.3%), osteoarthritis in six cases (18.1%), osteolysis associated with osteoarthritis in four cases(12.1%), and steel hook broken in one case (3%). The use of hook plate on open reduction and internal fixation of the acromioclavicular joint dislocation had little adverse effect on shoulder function and is an effective method for the treatment of acromioclavicular joint dislocation. Osteoarthritis and osteolysis are the two common complications after hook plate use, which are associated with the impairment of shoulder function. Shoulder function will be improved after removal of the hook plate.

  4. [Treatment of sternoclavicular joint dislocation with sternoclavicular hook plate fixation].

    PubMed

    Liu, Pan; Yuan, Jia-bin; Liu, Zhong-qian; Lu, Bing; Wang, Yue

    2015-08-01

    To evaluate the technique and therapeutic effect of sternoclavicular hook plate fixation in treating sternoclavicular joint (SCJ) dislocation. From January 2010 to March 2014,6 patients with SCJ dislocation were treated with sternoclavicular hook plate fixation in our hospital. Among the 6 patients, 5 patients were male and 1 patient was female, and the average age was 34 years, ranging from 26 to 48 years. The course of the disease ranged from 3 to 20 days. All the SCJ dislocations were caused by external injury and accompanied with the symptoms of swelling pain and obvious shoulder joint activity restricted in affected side. All SCJ dislocations were anterior dislocation by the diagnosis of X-ray and CT scan. The postoperative curative effect was evaluated according to Rockwood score. All the patients' operative incision were healed well and in good appearance. X-ray showed that the dislocated SCJ was well reduced and the plate was on right position. All the 6 patients were followed up for 4 to 18 months, with an average of 12 months. The results were evaluated according to Rockwood score, 4 got excellent results, 1 good and 1 fair. No fixation loosening, redislocation or side injury such as vessel, nerve or pleura injury were found. With sternoclavicular hook plate fixation, SCJ dislocation could be reduced while keeping its amphiarthrodial function and the completeness of the cartilage surface. Sternoclavicular hook plate fixation has advantages of safety and stabilization in fixation, and patients can begin function exercises earlier.

  5. K-wire and tension band wire fixation in treating sternoclavicular joint dislocation.

    PubMed

    Chen, Qing-yu; Cheng, Shao-wen; Wang, Wei; Lin, Zhong-qin; Zhang, Wei; Kou, Dong-quan; Shen, Yue; Ying, Xiao-zhou; Cheng, Xiao-jie; Lv, Chuan-zhu; Peng, Lei

    2011-02-01

    To evaluate the feasibility and therapeutic effect of treating sternoclavicular joint dislocation by K-wire and tension band wire fixation, and to improve the safety and stability of this technique. This study consisted of 9 cases, 6 males and 3 females with the mean age of 25 years (range, 9-62 years). The causes were traffic accident in 7 cases, falling in 1 case and fight in 1 case. The duration from injury to operation was 2 hours to 7 days. There were 5 left dislocations and 4 right dislocations; 8 anterior dislocations and 1 posterior dislocation, including one combined with left scapular fracture and one with left olecranon fracture. Open reduction and internal fixation using K-wires and tension band wires were performed to treat dislocations. All patients were followed up for 6 to 24 months, 10 months on average. According to Rockwood's rating scale on postoperative sternoclavicular joint, 8 cases achieved excellent outcomes with an average score of 13.88, and the rest case achieved a good outcome with the score of 12. Anatomical reduction was obtained in all cases. There were no such postoperative complications as severe infection, injury to blood vessel and nerve, failure of fixation, etc. Patients were all satisfied with the anatomical reduction and functional recovery. The technique of K-wire and tension band wire fixation is safe, simple, effective, less invasive and has been successfully used in orthopedic surgery. It is effective in treating sternoclavicular joint dislocation though it has some disadvantages.

  6. A new technique for repair of a dislocated sternoclavicular joint using a sternal tension cable system.

    PubMed

    Janson, Jacques T; Rossouw, Gawie J

    2013-02-01

    An unstable anterior or posterior sternoclavicular joint dislocation can cause severe morbidity with poor shoulder movement and strength. These dislocations need to be repaired, which can be challenging. Many different procedures have been described to obtain a stable joint fixation with varying results. We report a new technique for repairing a sternoclavicular joint dislocation by using a figure-of-eight sternal cable system. This procedure is relatively simple and reproducible to create a stable and functional sternoclavicular joint. Copyright © 2013 The Society of Thoracic Surgeons. Published by Elsevier Inc. All rights reserved.

  7. RETURN TO DIVISION IA FOOTBALL FOLLOWING A 1ST METATARSOPHALANGEAL JOINT DORSAL DISLOCATION

    PubMed Central

    Cook, Chad; Zarzour, Hap; Moorman, Claude T.

    2010-01-01

    Background. Although rare in occurrence, a dorsal dislocation of the 1st metatarsophalangeal (MTP) joint has been successfully treated using surgical and/or non-operative treatment. No descriptions of conservative intervention following a dorsal dislocation of the MTP joint in an athlete participating in a high contact sport are present in the literature. Objectives. The purpose of this case report is to describe the intervention and clinical reasoning during the rehabilitative process of a collegiate football player diagnosed with a 1st MTP joint dorsal dislocation. The plan of care and return to play criteria used for this athlete are presented. Case Description. The case involved a 19-year-old male Division IA football player, who suffered a traumatic dorsal dislocation of the 1st MTP joint during practice. The dislocation was initially treated on-site by closed reduction. Non-operative management included immobilization, therapeutic exercises, non-steroidal anti-inflammatories, manual treatment, modalities, prophylactic athletic taping, gait training, and a sport specific progression program for full return to Division IA football. Outcomes. Discharge from physical therapy occurred after six weeks of treatment. At discharge, no significant deviations existed during running, burst, and agility related drills. At a six-month follow-up, the patient reported full return to all football activities including contact drills without restrictions. Discussion. This case describes an effective six-week rehabilitation intervention for a collegiate football player who sustained a traumatic great toe dorsal dislocation. Further study is suggested to evaluate the intervention strategies and timeframe for return to contact sports. PMID:21589669

  8. Effects of hook plate on shoulder function after treatment of acromioclavicular joint dislocation

    PubMed Central

    Chen, Chang-Hong; Dong, Qi-Rong; Zhou, Rong-Kui; Zhen, Hua-Qing; Jiao, Ya-Jun

    2014-01-01

    Introduction: Internal fixation with hook plate has been used to treat acromioclavicular joint dislocation. This study aims to evaluate the effect of its use on shoulder function, to further analyze the contributing factors, and provide a basis for selection and design of improved internal fixation treatment of the acromioclavicular joint dislocation in the future. Methods: A retrospective analysis was performed on patients treated with a hook plate for acromioclavicular joint dislocation in our hospital from January 2010 to February 2013. There were 33 cases in total, including 25 males and 8 females, with mean age of 48.27 ± 8.7 years. There were 29 cases of Rockwood type III acromioclavicular dislocation, 4 cases of type V. The Constant-Murley shoulder function scoring system was used to evaluate the shoulder function recovery status after surgery. Anteroposterior shoulder X-ray was used to assess the position of the hook plate, status of acromioclavicular joint reduction and the occurrence of postoperative complications. Results: According to the Constant-Murley shoulder function scoring system, the average scores were 78 ± 6 points 8 to 12 months after the surgery and before the removal of the hook plate, the average scores were 89 ± 5 minutes two months after the removal of hook plate. Postoperative X-ray imaging showed osteolysis in 10 cases (30.3%), osteoarthritis in six cases (18.1%), osteolysis associated with osteoarthritis in four cases(12.1%), and steel hook broken in one case (3%). Conclusion: The use of hook plate on open reduction and internal fixation of the acromioclavicular joint dislocation had little adverse effect on shoulder function and is an effective method for the treatment of acromioclavicular joint dislocation. Osteoarthritis and osteolysis are the two common complications after hook plate use, which are associated with the impairment of shoulder function. Shoulder function will be improved after removal of the hook plate. PMID

  9. [Bilateral chronic dislocation of the temporomandibular joints and Meige syndrome].

    PubMed

    Arzul, L; Henoux, M; Marion, F; Corre, P

    2015-04-01

    Chronic dislocation of the temporo-mandibular joint (TMJ) is rare. It occurs when an acute dislocation is left untreated, in certain situations, including severe illness, neurologic or psychiatric diseases or prolonged oral intubation. A 79 years old woman, with Meige syndrome, suffered from bilateral dislocation of the TMJ for over 1 year. Surgical repositioning of the mandibular condyles and temporal bone eminectomy were performed. At the 18 postoperative months control, no recurrence has been noted. Treatment of chronic TMJ dislocations often requires a surgical procedure. Manual reduction, even under general anaesthesia, often fails because of severe muscular spasm and periarticular fibrotic changes. The management of this disorder is still controversial. We review available surgical procedures. Copyright © 2015 Elsevier Masson SAS. All rights reserved.

  10. Changes in surgical procedures for acromioclavicular joint dislocation over the past 30 years.

    PubMed

    Takase, Katsumi; Yamamoto, Kengo

    2013-10-01

    Generally, surgical treatment is recommended for Rockwood type 5 traumatic acromioclavicular joint dislocations. Since 1980, the authors have performed the modified Dewar procedure, the modified Cadenat procedure, and anatomical reconstruction of the coracoclavicular ligaments for this injury. The goal of this study was to determine the ideal surgical procedure for acromioclavicular joint dislocations by comparing these 3 procedures. The modified Dewar procedure was performed on 55 patients (Dewar group), the modified Cadenat procedure was performed on 73 patients (Cadenat group), and anatomical reconstruction of the coracoclavicular ligaments was performed on 11 patients (reconstruction group). According to the UCLA scoring system, therapeutic results averaged 27.3 points in the Dewar group, 28.2 in the Cadenat group, and 28.4 in the reconstruction group. The incidence of residual subluxation or dislocation in the acromioclavicular joint was evaluated at final radiographic follow-up. Subluxation occurred in 21 patients in the Dewar group, 18 in the Cadenat group, and 3 in the reconstruction group. Dislocation occurred in 3 patients in the Dewar group. Osteoarthritic changes in the acromioclavicular joint occurred in 20 patients in the Dewar group, 9 in the Cadenat group, and 1 in the reconstruction group. The modified Cadenat procedure can provide satisfactory therapeutic results and avoid postoperative failure or loss of reduction compared with the modified Dewar procedure. However, the modified Cadenat procedure does not anatomically restore the coracoclavicular ligaments. Anatomic restoration of both coracoclavicular ligaments can best restore acromioclavicular joint function. Copyright 2013, SLACK Incorporated.

  11. Surgical versus conservative management of Type III acromioclavicular dislocation: a systematic review.

    PubMed

    Longo, Umile Giuseppe; Ciuffreda, Mauro; Rizzello, Giacomo; Mannering, Nicholas; Maffulli, Nicola; Denaro, Vincenzo

    2017-06-01

    The management of Type III acromioclavicular (AC) dislocations is still controversial. We wished to compare the rate of recurrence and outcome scores of operative versus non-operative treatment of patients with Type III AC dislocations. A systematic review of the literature was performed by applying the PRISMA guidelines according to the PRISMA checklist and algorithm. A search in Medline, PubMed, Cochrane and CINAHL was performed using combinations of the following keywords: 'dislocation', 'Rockwood', 'type three', 'treatment', 'acromioclavicular' and 'joint'. Fourteen studies were included, evaluating 646 shoulders. The rate of recurrence in the surgical group was 14%. No statistical significant differences were found between conservative and surgical approaches in terms of postoperative osteoarthritis and persistence of pain, although persistence of pain seemed to occur less frequently in patients undergoing a surgical treatment. Persistence of pain seemed to occur less frequently in patients undergoing surgery. Persistence of pain seems to occur less frequently in patients treated surgically for a Type III AC dislocation. There is insufficient evidence to establish the effects of surgical versus conservative treatment on functional outcome of patients with AC dislocation. High-quality randomized controlled clinical trials are needed to establish whether there is a difference in functional outcome. © The Author 2017. Published by Oxford University Press. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com

  12. A Rare Case of Morel-Lavallee Syndrome Complicating an Anterior Dislocation of Hip Joint.

    PubMed

    Nekkanti, Supreeth; Vijay, C; Theja, Sujana; Shankar, R Ravi; Verma, Anubhav

    2016-01-01

    Hip dislocations are serious injuries as hip joint is an extremely stable joint. It requires a significant amount of force to produce such an injury. Anterior dislocations are uncommon. Potential complications of anterior hip dislocations are a neurovascular injury to femoral vessels or acetabular fractures. We report a rare late complication of Morel-Lavallee syndrome occurring 3 weeks after an anterior dislocation of the hip in a 43-year-old male. The patient presented to us with history. Morel-Lavallee syndrome is a rare complication. However if diagnosed early can be successfully treated with minimal burden to the patient. The authors recommend surgeons to have a high index of suspicion for this syndrome and a stringent follow-up examination of the patient.

  13. Bilateral sacroiliac joint dislocation (anterior and posterior) with triradiate cartilage injury: a case report.

    PubMed

    Lee, Dae-Hee; Jeong, Woong-Kyo; Inna, Prashanth; Noh, Won; Lee, Dong-Ki; Lee, Soon-Hyuck

    2011-12-01

    Pediatric sacroiliac joint injuries are uncommon. Significant pelvis ring disruptions in children are rare, and their management is complicated by patient size, differences in bony architecture, and future growth and remodeling potential. We present a rare case of anterior sacroiliac joint dislocation associated with triradiate cartilage injury with a posterior sacroiliac dislocation on the contralateral side. This appears to be the first such case reported in the literature.

  14. Postoperative Therapy for Chronic Thumb Carpometacarpal (CMC) Joint Dislocation.

    PubMed

    Wollstein, Ronit; Michael, Dafna; Harel, Hani

    2016-01-01

    Surgical arthroplasty of thumb carpometacarpal (CMC) joint osteoarthritis is commonly performed. Postoperative therapeutic protocols aim to improve range of motion and function of the revised thumb. We describe a case in which the thumb CMC joint had been chronically dislocated before surgery, with shortening of the soft-tissue dynamic and static stabilizers of the joint. The postoperative protocol addressed the soft tissues using splinting and exercises aimed at lengthening and strengthening these structures, with good results. It may be beneficial to evaluate soft-tissue tension and the pattern of thumb use after surgery for thumb CMC joint osteoarthritis to improve postoperative functional results. Copyright © 2016 by the American Occupational Therapy Association, Inc.

  15. Complete acromioclavicular joint dislocation treated with reconstructed ligament by trapezius muscle fascia and observation of fascial metaplasia.

    PubMed

    Wang, Chaoliang; Huang, Sufang; Wang, Yingzhen; Sun, Xuesheng; Zhu, Tao; Li, Qiang; Lin, Chu

    2015-01-01

    We evaluated the long-term clinical results of acute complete acromioclavicular dislocations treated by reconstruction of the acromioclavicular and coracoclavicular ligament using trapezius muscle fascia. Open reduction and internal fixation was performed using the clavicular hook plate in 12 patients with acute complete acromioclavicular joint dislocation, and the acromioclavicular and coracoclavicular ligaments were reconstructed using trapezius muscle fascia. Radiographic evaluations were conducted postoperatively. We evaluated the functional results with constant scoring system and radiological results at the final follow-up visit. The mean Constant score at the final follow-up visit was 91.67 (range, 81 to 100). The results were excellent in eight patients (66.7%) and good in four patients (33.3%). Three patients with scores from 80 to 90 had mild pain during activity, but this did not affect the range of motion of the shoulder. All patients have returned to their preoperative work without any limitations. Compared with the contralateral side, radiography showed anatomical reposition in the vertical plane in all cases. The hook-plate fixation with ligament reconstruction was successful in treating AC dislocations. The acromioclavicular and coracoclavicular ligament were reconstructed by trapezius muscle fascia that keep the distal clavicle stable both vertically and horizontally after type III injuries.

  16. Complete acromioclavicular joint dislocation treated with reconstructed ligament by trapezius muscle fascia and observation of fascial metaplasia

    PubMed Central

    Wang, Chaoliang; Huang, Sufang; Wang, Yingzhen; Sun, Xuesheng; Zhu, Tao; Li, Qiang; Lin, Chu

    2015-01-01

    We evaluated the long-term clinical results of acute complete acromioclavicular dislocations treated by reconstruction of the acromioclavicular and coracoclavicular ligament using trapezius muscle fascia. Open reduction and internal fixation was performed using the clavicular hook plate in 12 patients with acute complete acromioclavicular joint dislocation, and the acromioclavicular and coracoclavicular ligaments were reconstructed using trapezius muscle fascia. Radiographic evaluations were conducted postoperatively. We evaluated the functional results with constant scoring system and radiological results at the final follow-up visit. The mean Constant score at the final follow-up visit was 91.67 (range, 81 to 100). The results were excellent in eight patients (66.7%) and good in four patients (33.3%). Three patients with scores from 80 to 90 had mild pain during activity, but this did not affect the range of motion of the shoulder. All patients have returned to their preoperative work without any limitations. Compared with the contralateral side, radiography showed anatomical reposition in the vertical plane in all cases. The hook-plate fixation with ligament reconstruction was successful in treating AC dislocations. The acromioclavicular and coracoclavicular ligament were reconstructed by trapezius muscle fascia that keep the distal clavicle stable both vertically and horizontally after type III injuries. PMID:28352721

  17. Biomechanical analysis of acromioclavicular joint dislocation repair using coracoclavicular suspension devices in two different configurations.

    PubMed

    Abat, Ferran; Sarasquete, Juan; Natera, Luis Gerardo; Calvo, Ángel; Pérez-España, Manuel; Zurita, Néstor; Ferrer, Jesús; del Real, Juan Carlos; Paz-Jimenez, Eva; Forriol, Francisco

    2015-09-01

    The best treatment option for some acromioclavicular (AC) joint dislocations is controversial. For this reason, the aim of this study was to evaluate the vertical biomechanical behavior of two techniques for the anatomic repair of coracoclavicular (CC) ligaments after an AC injury. Eighteen human cadaveric shoulders in which repair using a coracoclavicular suspension device was initiated after injury to the acromioclavicular joint were included in the study. Three groups were formed; group I (n = 6): control; group II (n = 6): repair with a double tunnel in the clavicle and in the coracoid (with two CC suspension devices); group III (n = 6): repair in a "V" configuration with two tunnels in the clavicle and one in the coracoid (with one CC suspension device). The biomechanical study was performed with a universal testing machine (Electro Puls 3000, Instron, Boulder, MA, USA), with the clamping jaws set in a vertical position. The force required for acromioclavicular reconstruction system failure was analyzed for each cadaveric piece. Group I reached a maximum force to failure of 635.59 N (mean 444.0 N). The corresponding force was 939.37 N (mean 495.6 N) for group II and 533.11 N (mean 343.9 N) for group III. A comparison of the three groups did not find any significant difference despite the loss of resistance presented by group III. Anatomic repair of coracoclavicular ligaments with a double system (double tunnel in the clavicle and in the coracoid) permits vertical translation that is more like that of the acromioclavicular joint. Acromioclavicular repair in a "V" configuration does not seem to be biomechanically sufficient.

  18. Operative Versus Non-operative Treatment of Grade III Acromioclavicular Joint Dislocations and the Use of SurgiLig: a Retrospective Review.

    PubMed

    Younis, Fizan; Ajwani, Sanil; Bibi, Asia; Riley, Eleanor; Hughes, Peter J

    2017-12-30

    Acromioclavicular joint dislocations are common shoulder girdle injuries. The treatment of grade III acromioclavicular joint dislocations is controversial. Furthermore, the literature on the use of the Sur-giligTM synthetic ligament for reconstruction of dislocations is sparse. This retrospective review aimed to establish whether operative treatment was superior to non-operative treatment in grade III acromioclavicular joint dislocations treated at our institute over a 5-year period. We also reviewed the effectiveness of reconstruction with SurgiligTM after acute and chronic dislocations across all grades of acromioclavicular joint dislocations. Twenty-five patients completed full follow-up with grade III dislocations. The mean follow-up in the operated group was 3.56 years and in the non-operated group this was 3.29 years. The mean Oxford Shoul-der Score (OSS) in the operated group was 39.8, whereas the mean OSS in the non-operated group was 45.9 (p=0.01). The mean pain score in the operated group was 2.2, and in the non-operated group this was 1.6. The mean satisfaction score in the operated group was 8.2 and that in the non-operated group was 7.8. There was no statistically significant difference in pain or satisfaction scores. In respect to the cohort treated with Surg-iligTM synthetic ligament, 22 patients across all grades of dislocations had this procedure performed. The mean post-operative Oxford Shoulder Score (OSS) was 40. 1. Non-operative treatment is not inferior to operative treatment for grade III acromioclavicular joint dislocations. The data from this study demonstrat-ed that the non-operated group had superior Ox-ford Shoul-der Scores that were statistically significant. 2. Additionally, the use of the SurgiligTM ligament appears to be effective in treating both chronic and acute acromioclavicular joint dislocations.

  19. [Arthroscopic therapy of ankle joint impingement syndrome after operation of ankle joint fracture dislocation].

    PubMed

    Feng, Zhibin; Mi, Kun; Wei, Renzhi; Liu, Wu; Wang, Bin

    2011-07-01

    To study the operative procedure and the effectiveness of arthroscopic therapy for ankle joint impingement syndrome after operation of ankle joint fracture dislocation. Between March 2008 and April 2010, 38 patients with ankle joint impingement syndrome after operation of ankle joint fracture dislocation were treated. Among them, there were 28 males and 10 females with an average age of 28 years (range, 18 to 42 years). The time from internal fixation to admission was 12-16 months (mean, 13.8 months). There were pressing pain in anterolateral and anterior ankle. The dorsal extension ranged from -20 to -5 degrees (mean, -10.6 degrees), and the palmar flexion was 30-40 degrees (mean, 35.5 degrees). The total score was 48.32 +/- 9.24 and the pain score was 7.26 +/- 1.22 before operation according to American Orthopaedic Foot and Ankle Society (AOFAS) ankle and hindfoot score system. The X-ray films showed osteophyte formation in anterior tibia and talus; MRI showed cartilage injury in 22 cases. Arthroscopic intervention included removing osteophytes, debriding fabric scars and synovial membrane tissues, and removing osteochondral fragments. Arthroscopic microfracture technique was used in 22 patients with cartilage injury. All incisions healed primarily. Thirty-eight cases were followed up 10-26 months (mean, 16 months). At last follow-up, 26 patients had normal range of motion (ROM); the dorsal extension was 15-25 degrees (mean, 19.6 degrees) and the palmar flexion was 35-45 degrees (mean, 40.7 degrees). Eight patients had mild limited ROM; the dorsal extension was 5-15 degrees (mean, 7.2 degrees) and the palmar flexion was 35-45 degrees (mean, 39.5 degrees). Four patients had mild limited ROM and pain in posterior portion of the ankle after a long walking (3-4 hours); the dorsal extension was 0-5 degrees (mean, 2.6 degrees) and the palmar flexion was 35-40 degrees (mean, 37.5 degrees). The total score was 89.45 +/- 9.55 and the pain score was 1.42 +/- 1.26 after

  20. [Tossy III injuries of the acromioclavicular joint. In what circumstances is surgery still justified? Personal results and literature review].

    PubMed

    Prokop, A; Helling, H J; Andermahr, J; Mönig, S; Rehm, K E

    2003-05-01

    In Germany AC-joint-dislocations type Tossy III are treated in most of the cases operatively. Over two times of period we treated AC-joint-dislocations type Tossy III with biodegradable PDS-cords. 54 patients were operated between 1989 and 1997 and followed up after 39 months. 87.5% of patients are satisfied with results and have 10.2 points at Taftscore. In this period we couldn't differentiated the results by Rockwood classification. 12 patients with Rockwood V were operated between 1998 and 2002 and followed up after 14 months. Excellent and good results were seen in 92% of cases. At Taftscore we seen 10.7 points. 3 patients with Rockwood III were treated conservative with 10.3 points and 3 patients were operated with 10.7 points at Taftscore. AC-joint dislocations should be classified to Rockwood. No differences were seen between operation and conservative treatment in Rockwood III in literature. We recommend operation with PDS cords with good results in Rockwood V.

  1. Concurrent dorsal dislocations and fracture-dislocations of the index, long, ring, and small (second to fifth) carpometacarpal joints.

    PubMed

    Prokuski, L J; Eglseder, W A

    2001-11-01

    To review the outcome of patients with concurrent dorsal dislocations and fracture-dislocations of the second, third, fourth, and fifth carpometacarpal (CMC) joints treated with open reduction and internal fixation (ORIF). Retrospective review. Level 1 trauma center. Between 1991 and 1997, twelve multiply injured patients with the described CMC injury complex (one open injury) were treated with ORIF (eleven patients) or percutaneous wire fixation (one patient) by the same surgeon. Treatment consisted of ORIF with Kirschner wires followed by splints and immediate metacarpophalangeal and interphalangeal joint range of motion exercises. Grip strength, wrist and finger range of motion, pain, need for additional surgery, and return to work. Of the ten patients available for follow-up (mean, three years), all had been treated with ORIF (eight within forty-eight hours of injury and two had treatment delayed for four weeks because of delayed diagnosis and management of more serious injuries). Three patients had additional surgery (planned secondary second and third CMC arthrodeses). Grip strength of the operated hand in the five patients with JAMAR testing was 50 percent (n = 3), 75 percent (n = 1), and 90 percent (n = 1) of that in their contralateral hands. Five patients were pain-free, and five reported occasional, activity-related pain. The five patients who worked before the injury returned to their previous occupations (one with slightly modified duties). This is the largest series of patients with this CMC injury complex and the first report of open CMC dorsal dislocations and fracture-dislocations. Although early ORIF is suggested, delay of up to four weeks did not adversely affect results.

  2. Dislocation

    MedlinePlus

    ... Dislocations can occur in contact sports, such as football and hockey, and in sports in which falls ... downhill skiing, gymnastics and volleyball. Basketball players and football players also commonly dislocate joints in their fingers ...

  3. [Joint dislocation after total knee arthroplasty as an ankle fracture complication. Case report].

    PubMed

    Hrubina, M; Skoták, M

    2012-01-01

    Joint dislocation after total knee arthroplasty is a rare complication. It is described as the result of ligamentous instability. Here we report the case of an 82-year-old women who underwent primary total knee arthroplasty (TKA) for advanced primary grade III gonarthrosis. At 3 post-operative months the joint was stable and painless, with radiographic evidence of good TKA alignment and integration. At 4 months the patient suffered injury to the ankle involving a bimalleolar fracture and damage to knee soft tissues. The fracture was surgically treated. Subsequently, dorsal tibial dislocation was manifested. This was managed by individual intramedullary nail arthrodesis. At 8 months following the operation, the knee condition was satisfactory, with rigid arthrodesis and leg shortening of 4 cm. The patient was satisfied because she was free of pain and able to walk. Arthrodesis of the knee joint with an individual nail is an option for a definitive treatment of TKA instability. When other joints, such as ankle or hip joints, are injured, it is recommended to pay attention also to any TKA implanted previously because of potential development of instability or infection.

  4. Recurrent dislocation of the temporomandibular joint: a literature review and two case reports treated with eminectomy.

    PubMed

    Martins, Wilson Denis; Ribas, Marina de Oliveira; Bisinelli, Julio; França, Beatriz Helena S; Martins, Guilherme

    2014-04-01

    Dislocation of the temporomandibular joint (TMJ) is a troublesome condition that occurs in a chronic or acute form. It is a distressing and highly embarrassing situation that may occur as a result of daily activities such as yawning, laughing, or during events that require keeping the mouth open for a long time. This review aims to present and discuss different conservative and surgical techniques to treat patients with a dislocated mandible, and to present two cases of surgical treatment. A search of the literature was completed (Medline, PubMed) using the keywords TMJ dislocation, TMJ luxation, mandibular dislocation and surgical and non-surgical methods of treatment for this condition. Eminectomy (Myrhaug's surgery) has been used with satisfactory results. Most of reports present large series of patients with more than one year of follow-up and no recurrence of complications. Is less invasive and take a short operation time; need no bone transplantation or placing any kind of foreign body into the joint. Eminectomy results in long-term resolution of recurrent TMJ dislocations, when compared with others surgical techniques.

  5. Controversies relating to the management of acromioclavicular joint dislocations.

    PubMed

    Modi, C S; Beazley, J; Zywiel, M G; Lawrence, T M; Veillette, C J H

    2013-12-01

    The aim of this review is to address controversies in the management of dislocations of the acromioclavicular joint. Current evidence suggests that operative rather than non-operative treatment of Rockwood grade III dislocations results in better cosmetic and radiological results, similar functional outcomes and longer time off work. Early surgery results in better functional and radiological outcomes with a reduced risk of infection and loss of reduction compared with delayed surgery. Surgical options include acromioclavicular fixation, coracoclavicular fixation and coracoclavicular ligament reconstruction. Although non-controlled studies report promising results for arthroscopic coracoclavicular fixation, there are no comparative studies with open techniques to draw conclusions about the best surgical approach. Non-rigid coracoclavicular fixation with tendon graft or synthetic materials, or rigid acromioclavicular fixation with a hook plate, is preferable to fixation with coracoclavicular screws owing to significant risks of loosening and breakage. The evidence, although limited, also suggests that anatomical ligament reconstruction with autograft or certain synthetic grafts may have better outcomes than non-anatomical transfer of the coracoacromial ligament. It has been suggested that this is due to better restoration horizontal and vertical stability of the joint. Despite the large number of recently published studies, there remains a lack of high-quality evidence, making it difficult to draw firm conclusions regarding these controversial issues.

  6. Midshaft clavicle fractures with associated ipsilateral acromioclavicular joint dislocations: Incidence and risk factors.

    PubMed

    Ottomeyer, Christina; Taylor, Benjamin C; Isaacson, Mark; Martinez, Lara; Ebaugh, Pierce; French, Bruce G

    2017-02-01

    Simultaneous ipsilateral clavicle and acromioclavicular (AC) joint injury have been infrequently reported in the literature at this time. The purpose of this study was to assess incidence as well as assess risk factors for this dual injury pattern. We performed a retrospective review of a prospectively collected database (Level III evidence), evaluating 383 adult patients without previous shoulder girdle injury or trauma with a minimum 1-year follow-up who sustained a displaced diaphyseal clavicle fracture. All patients in the study underwent either nonoperative management or surgical reduction and stabilization of a diaphyseal clavicle fracture with a plate and screw construct. Study subjects were followed with serial radiographs. Clavicle and shoulder radiographs, as well as chest radiographs and contralateral films in questionable cases, were used to assess for acromioclavicular joint injury in both operative and nonoperative groups. Additional data was collected on concurrent injuries, patient demographics, fracture characteristics, fixation techniques, surgical/post-operative data, and operative or nonoperative treatment. We found that 13/183 (7.1%) of patients undergoing fixation of a diaphyseal clavicle fracture had an ipsilateral AC joint injury, while 13/200 (6.5%) of patients undergoing conservative management had an ipsilateral AC joint injury. Critical analysis of the data revealed that presence of ipsilateral scapular body fractures, and a likely incidental association with superior plating fixation, were associated with an increased rate of this injury pattern. Ipsilateral clavicle fracture and AC joint injury is much more common than traditionally believed, with an incidence of 6.8% overall. It is unknown how the presence of an associated AC injury influences outcome, as AC injury was not universally symptomatic. Copyright © 2016 Elsevier Ltd. All rights reserved.

  7. Chronic bilateral dislocation of temporomandibular joint.

    PubMed

    Shakya, S; Ongole, R; Sumanth, K N; Denny, C E

    2010-01-01

    Dislocation of the condyle of the mandible is a common condition that may occur in an acute or chronic form. It is characterised by inability to close the mouth with or without pain. Dislocation has to be differentiated from subluxation which is a self reducible condition. Dislocation can occur in any direction with anterior dislocation being the commonest one. Various predisposing factors have been associated with dislocation like muscle fatigue and spasm, the defect in the bony surface like shallow articular eminence, and laxity of the capsular ligament. People with defect in collagen synthesis like Ehler Danlos syndrome, Marfan syndrome are said to be genetically predisposed to this condition. Various treatment modalities have been used ranging from conservative techniques to surgical methods. Acute dislocations can be reduced manually or with conservative approach and recurrent and chronic cases can be reduced by surgical intervention. Though the dislocation in our case was 4 months a simple manual reduction proved to be successful. We believe that manual reduction can be attempted as first line of treatment prior to surgical intervention.

  8. Comparison of hook plate with versus without double-tunnel coracoclavicular ligament reconstruction for repair of acute acromioclavicular joint dislocations: A prospective randomized controlled clinical trial.

    PubMed

    Yin, Jian; Yin, Zhaoyang; Gong, Ge; Zhu, Chao; Sun, Chao; Liu, Xinhui

    2018-06-01

    This study was designed to compare the surgical outcomes of a hook plate with double-tunnel coracoclavicular (CC) ligament reconstruction by conjoined tendon transfer versus single hook plate surgery for the repair of acute type of Rockwood type III and V acromioclavicular (AC) joint dislocations. The study cohort included 62 patients with acute (within 6 weeks after trauma) Rockwood type III and V AC joint dislocations who underwent surgery from February 2012 to September 2015. The patients were randomly allocated to the ligament reconstruction group (LR group, n = 31) or the single hook plate group (HP group, n = 31). In both groups, reduction of the AC joint by hook plate and repair of the ruptured AC ligament with absorbable Vicryl sutures were performed homoplastically. The lateral half of the short tendon of the biceps brachii muscle and the lateral half of the flexor tendon were used to reconstruct the trapezoid and conoid ligaments, respectively. Differences in surgical duration, intraoperative blood loss, incision length, and total cost were compared between the two groups. Furthermore, the preoperative and postoperative visual analogue score (VAS), postoperative American Shoulder and Elbow Surgeons (ASES) score, Constant-Murley score (CMS), Karlsson score, complication rates, and patient satisfaction at the last follow-up were compared to evaluate the curative effects of the surgical treatments. Magnetic resonance imaging (MRI) after hook plate removal was used to evaluate the reconstructed ligaments and tendon-bone interface. In total, 25 patients in the LR group and 26 in the HP group completed the follow-up. There were no statistically significant differences in age, sex, Rockwood type, placing time, total cost, and follow-up duration between the LR and HP groups (p > 0.05). However, as compared with the HP group, the surgical duration and incision length were longer in the LR group (92.08 ± 19.25 vs. 56.54 ± 21.29 min and 13

  9. The patellofemoral joint: from dysplasia to dislocation

    PubMed Central

    Zaffagnini, Stefano; Grassi, Alberto; Zocco, Gianluca; Rosa, Michele Attilo; Signorelli, Cecilia; Muccioli, Giulio Maria Marcheggiani

    2017-01-01

    Patellofemoral dysplasia is a major predisposing factor for instability of the patellofemoral joint. However, there is no consensus as to whether patellofemoral dysplasia is genetic in origin, caused by imbalanced forces producing maltracking and remodelling of the trochlea during infancy and growth, or due to other unknown and unexplored factors. The biomechanical effects of patellofemoral dysplasia on patellar stability and on surgical procedures have not been fully investigated. Also, different anatomical and demographic risk factors have been suggested, in an attempt to identify the recurrent dislocators. Therefore, a comprehensive evaluation of all the radiographic, MRI and CT parameters can help the clinician to assess patients with primary and recurrent patellar dislocation and guide management. Patellofemoral dysplasia still represents an extremely challenging condition to manage. Its controversial aetiology and its complex biomechanical behaviour continue to pose more questions than answers to the research community, which reflects the lack of universally accepted guidelines for the correct treatment. However, due to the complexity of this condition, an extremely personalised approach should be reserved for each patient, in considering and addressing the anatomical abnormalities responsible for the symptoms. Cite this article: EFORT Open Rev 2017;2. DOI: 10.1302/2058-5241.2.160081. Originally published online at www.efortopenreviews.org PMID:28630757

  10. [Case-control study on endobutton plate or clavicular hook plate for the repair of acromioclavicular joint dislocations].

    PubMed

    Zhu, Li; Yang, He-Jie; Zhao, Wan-Jun; Yang, Wu-Min; Zhou, Hui

    2012-02-01

    To compare the treatment results between Endobutton plate and clavicular hook plate for the treatment of acromioclavicular joint dislocations. From January 2009 to September 2010, 30 patients with acromioclavicular joint dislocations were treated with two different fixations: Endobutton plate (15 patients, including 12 males and 3 females, with a mean age of 38.5 +/- 8.2 years) and clavicular hook plate (15 patients, including 14 males and 1 female, with the mean age of 33.8 +/- 5.9 years). The mean operative time and blood loss were compared between the two groups. Joint function was assessed by the Karlsson standard. The mean operative time of the Endobutton group and the hook plate group were (61 +/- 8.6) min and (40 +/- 5.6) min. The average blood loss were (93 +/- 8.4) ml and (100 +/- 12.6) ml. There was no statistical difference between the two groups in the average blood loss and the mean operative time. According to the Karlsson standard, 13 patients got an excellent result, 2 good in the Endobutton group; and 7 patients got an excellent result and 7 good in hook plate group. The therapeutic effect in Endobutton group was better than that of hook plate group. In the treatment of acromioclavicular dislocation, fixation with Endobutton plate is believed to be better than hook plate fixation. It is an effective method for the repair of acromioclavicular joint dislocations in a short term. But its long term effects still need further follow up.

  11. Biomechanical analysis of acromioclavicular joint dislocation treated with clavicle hook plates in different lengths.

    PubMed

    Shih, Cheng-Min; Huang, Kui-Chou; Pan, Chien-Chou; Lee, Cheng-Hung; Su, Kuo-Chih

    2015-11-01

    Clavicle hook plates are frequently used in clinical orthopaedics to treat acromioclavicular joint dislocation. However, patients often exhibit acromion osteolysis and per-implant fracture after undergoing hook plate fixation. With the intent of avoiding future complications or fixation failure after clavicle hook plate fixation, we used finite element analysis (FEA) to investigate the biomechanics of clavicle hook plates of different materials and sizes when used in treating acromioclavicular joint dislocation. Using finite element analysis, this study constructed a model comprising four parts: clavicle, acromion, clavicle hook plate and screws, and used the model to simulate implanting different types of clavicle hook plates in patients with acromioclavicular joint dislocation. Then, the biomechanics of stainless steel and titanium alloy clavicle hook plates containing either six or eight screw holes were investigated. The results indicated that using a longer clavicle hook plate decreased the stress value in the clavicle, and mitigated the force that clavicle hook plates exert on the acromion. Using a clavicle hook plate material characterized by a smaller Young's modulus caused a slight increase in the stress on the clavicle. However, the external force the material imposed on the acromion was less than the force exerted on the clavicle. The findings of this study can serve as a reference to help orthopaedic surgeons select clavicle hook plates.

  12. [Repair and reconstruction for severe fracture and dislocation of ankle joint].

    PubMed

    Yin, Qingwei; Jiang, Yi; Xiao, Lianping; Li, Xiaodong; Fu, Jiaxin; Tian, Yonggang; Han, Liqiang; Liu, Zhi

    2008-06-01

    To summarize the technique and effect of the therapy for severe fracture and dislocation of ankle joint by operation. From March 2003 to February 2006, 76 cases were treated with primary open restoration and internal fixation for dislocated ankle joint fracture, with 47 males and 29 females, with the average age of 36.4 years (ranging from 18 years to 65 years). According to AO criterion, these fresh fractures were classified into 13 cases for type C3-1, 45 cases for type C3-2 and 18 cases for type C3-3. Based on the Gustilo-Anderson standard, 23 open fractures were classified into 17 cases for type II and 6 cases for type III A. The operation was delayed from 1 hours to 24 hours after the injury. All incisions healed at the first stage except 4 cases which delayed union because of simple infection by revision with ointment. A total of 72 cases were followed up, with the average time of 18.5 months (from 12 months to 35 months). The time of bone union was from 12 weeks to 24 weeks. The screws of fixation for lower tibia-fibula joint were found to be ruptured in 2 cases when further consultation was performed in the 16th and 20th week after the operation, respectively, and were broken within 1 year after the operation. These screws were taken out 12 weeks postoperative in 28 cases, while the whole internal fixations of the rest cases were taken out 1 year after the operation. The postoperative function of malleolus extended from 21.7 degrees to 26.8 degrees and flection from 38.5 degrees to 44.7 degrees. Assessed by the American Orthopaedic Foot and Ankle Society Clinical Rating Scales, 23 cases were excellent, 36 good, 13 fair, and the choiceness rate reached 81.94%. These procedures, together with reduction by twist after hospital, open and internal fixation in time, and parenchyma managed with internal fixation, are important to attain satisfactory effect for the treatment of severe fracture and dislocation of ankle joint.

  13. [Case control study of fractures-dislocations of ankle joint with conservative and operative treatment].

    PubMed

    Zhang, Song-Tu; Lin, Yi-Rong; Chen, Lian-Yuan

    2010-10-01

    To compare the clinical efficacy of grade III, IV supination-eversion fractures-dislocations of ankle joint between manipulative treatment and operative treatment. From September 2007 to December 2008, the clinical data of 60 patients with grade III, IV supination-eversion fractures-dislocations of ankle joint were retrospectively analyzed. There were 32 males and 28 females, ranging in age from 18 to 70 years with an average age of 38.17 years. All patients were respectively treated with manipulative treatment (conservative group, 30 cases) and operative treatment (operative group, 30 cases). The joint function was compared with Mazur standard; the reduction and shifting of fractures were observed with X-ray; the hospitalization day and the therapeutic cost were compared between two groups. All patients were followed up with an average of 15.27 months (ranged, 6 to 25 months). In conservative group, 16 cases got excellent result in joint function, 10 good, 3 fair, 1 poor; in operative group, 20 cases got excellent result, 8 good, 2 fair, 0 poor. In conservative group in the X-ray showed 25 cases obtained excellent and good reduction, 4 fair, 1 poor; and in operative group in the X-ray showed 28 cases obtained excellent and good reduction, 2 fair, 0 poor. There was no significant difference at the joint function and X-ray film after treatment between two groups (P > 0.05). The hospital day was respectively (7.87 +/- 3.34), (17.37 +/- 4.64) d in conservative group and operative group; and the therapeutic cost was respectively (2 506.67 +/- 649.10), (11 473.33 +/- 1 564.90) yuan. There was significant difference at hospital day and therapeutic cost between two groups (P < 0.05). Conservative treatment and operative treatment can both reach a very good result in treating grade III, IV supination-eversion fractures and dislocations of ankle joint. However, conservative treatment has advantage of high safety factor, low therapeutic cost, can reduce medical costs for

  14. Electromigration analysis of solder joints under ac load: A mean time to failure model

    NASA Astrophysics Data System (ADS)

    Yao, Wei; Basaran, Cemal

    2012-03-01

    In this study, alternating current (ac) electromigration (EM) degradation simulations were carried out for Sn95.5%Ag4.0%Cu0.5 (SAC405- by weight) solder joints. Mass transport analysis was conducted with viscoplastic material properties for quantifying damage mechanism in solder joints. Square, sine, and triangle current wave forms ac were used as input signals. dc and pulsed dc (PDC) electromigration analysis were conducted for comparison purposes. The maximum current density ranged from 2.2×106A/cm2 to 5.0×106A/cm2, frequency ranged from 0.05 Hz to 5 Hz with ambient temperature varying from 350 K to 450 K. Because the room temperature is nearly two-thirds of SAC solder joint's melting point on absolute temperature scale (494.15 K), viscoplastic material model is essential. Entropy based damage evolution model was used to investigate mean time to failure (MTF) behavior of solder joints subjected to ac stressing. It was observed that MTF was inversely proportional to ambient temperature T1.1 in Celsius and also inversely proportional to current density j0.27 in A/cm2. Higher frequency will lead to a shorter lifetime with in the frequency range we studied, and a relationship is proposed as MTF∝f-0.41. Lifetime of a solder joint subjected to ac is longer compared with dc and PDC loading conditions. By introducing frequency, ambient temperature and current density dependency terms, a modified MTTF equation was proposed for solder joints subjected to ac current stressing.

  15. Sports activity after anatomic acromioclavicular joint stabilisation with flip-button technique.

    PubMed

    Porschke, Felix; Schnetzke, Marc; Aytac, Sara; Studier-Fischer, Stefan; Gruetzner, Paul Alfred; Guehring, Thorsten

    2017-07-01

    Sports activity after surgical AC joint stabilisation has not been comprehensively evaluated to date. The aim of this study was to determine rate, level and time to return to sports after AC joint stabilisation and to identify the influence of overhead sports on post-operative sports activity. In this retrospective case series, a total of 68 patients with a high-grade AC joint dislocation (Rockwood type V) were stabilised using a single TightRope technique. Fifty-five patients (80.9 %) with median age of 42.0 (range, 18-65) years completed questionnaires regarding sports activity before and after surgery. Clinical outcome and complications were also evaluated. Forty-three patients participated in sports regularly before injury. Their sports activity was rated according to Allain, and non-overhead and overhead sports were differentiated. At median follow-up of 24 (18-45) months, 41 of 43 patients (95.3 %) had returned to sports. 63 % returned to the same sports activity as before injury. 16.3 % needed to adapt the type of sports to reduce demanding activities. 11.6 % reduced the frequency and 32.5 % the intensity of sports. The median time to return to sports was 9.5 (3-18) months. Overhead athletes (Allain Type III and IV) had to reduce their sports activity significantly more often (11.8 vs. 53.8 %; p = 0.011) and needed more time to return to sports (9.5 vs. 4.5 months; p = 0.009). After stabilisation of AC joint dislocation, the majority of patients returned to sports after a substantial period of time. Overhead athletes, in particular, required more time and had to considerably reduce their sports activity. The findings impact therapeutic decision-making after AC joint injury and help with the prognosis and assessment of rehabilitation progress. IV.

  16. Morphological analysis of acromion and hook plate for the fixation of acromioclavicular joint dislocation.

    PubMed

    Yoon, Jong Pil; Lee, Yeon Soo; Song, Geun Soo; Oh, Joo Han

    2017-03-01

    Acromioclavicular (AC) joint dislocation is a common sports injury. Hook plate fixation is currently widely used to treat this injury, as it can promote the natural healing of the ligament with good clinical outcomes. However, subacromial erosion and impingement are frequently observed post-operatively. It was hypothesized that the morphology and the contact characteristics between the hook portion and the acromion are the main causes of complications after hook plate fixation with the currently available commercial designs. Three-dimensional reconstructed models of the AC joint obtained from the computed tomographic scans of 23 male and 23 female patients (mean age, 61.1 ± 6.3 years) were evaluated, and multiple anatomical parameters were measured. For the subacromial positioning of the hook plate, an actual hook plate (Synthes Inc., West Chester, PA, USA) was scanned, and the contact between the hook plate and the acromion was estimated. The thicknesses of the acromion and distal clavicle were 9.7 ± 1.5 mm (10.7 mm in men; 8.6 mm in women) and 11.3 ± 1.6 mm (11.6 mm in men; 10.0 mm in women), respectively. The width of the acromion was 28.5 ± 3.6 mm. The mean inclination angle between the hook plate and the acromion was 29.3° ± 9.7° (27.9° in men; 30.6° in women). The hook plate made a point contact with the acromion at 9.2 ± 3.3 mm (31.5 %) from the lateral end of the acromion. The results revealed that the hook made a pinpoint contact with the undersurface of the acromion, and this might explain why complications commonly occur after hook plate fixation. The force concentration phenomenon associated with the hook plate of existing designs results from cases of morphological mismatch, such as excessive inclination and improper occupation of the subacromial space.

  17. Condylar Joint Fusion and Stabilization (by Screws and Plates) in Nontraumatic Atlanto-Occipital Dislocation: Technical Report of 2 Cases.

    PubMed

    Chowdhury, Forhad H; Haque, Mohammod Raziul; Alam, Sarwar Murshed; Khaled Chowdhury, S M Noman; Khan, Shamsul Islam; Goel, Atul

    2017-11-01

    Nontraumatic spontaneous atlanto-occipital dislocation (AOD) is rare. In this report, we discuss the technical steps of condylar joint fusion and stabilization (by screws and plates) in nontraumatic AOD. To the best of our knowledge, it is the first report of such techniques. A young girl and a young man with progressive quadriparesis due to nontraumatic spontaneous atlanto-occipital dislocation were managed by microsurgical reduction, fusion, and stabilization of the joint by occipital condylar and C1 lateral mass screw and plate fixation after mobilization of vertebral artery. In both cases, condylar joints fixation and fusion were done successfully. Condylar joint stabilization and fusion may be a good or alternative option for AOD. Copyright © 2017 Elsevier Inc. All rights reserved.

  18. A Case of Simultaneous Traumatic Dorsal Dislocation of All Five Metatarsophalangeal Joints Treated Successfully With Closed Reduction.

    PubMed

    Bhide, Pushkar P; Anantharaman, Chinnadurai; Mohan, Ganesan; Raju, Karuppanna

    2016-01-01

    Simultaneous dislocation of multiple metatarsophalangeal joints is a rare injury, because of the impediment presented by the anatomy of the lesser metatarsophalangeal joints. To the best of our knowledge, only 1 case of simultaneous dislocation of all 5 metatarsophalangeal joints has been previously reported in peer-reviewed studies. Owing to the same anatomic structures that obstruct relocation, closed reduction has been known to fail in a large proportion of cases. We report a case of simultaneous dorsal dislocation of all 5 metatarsophalangeal joints of the right foot after a motor vehicle accident. The highlight of our case was successful closed reduction after application of the reduction maneuver to all lesser metatarsophalangeal joints simultaneously in the second attempt with the patient under anesthesia. On confirming the stability of the reduction, the foot was immobilized in a short-leg, posterior slab cast for 3 weeks without placing Kirschner wires across the joints. At the 3-month follow-up evaluation, the patient had reacquired their preinjury level of activity with a good range of motion . At the 2-year follow-up evaluation, this range of motion was maintained with no radiologic evidence of arthrosis. We have inferred that the reduction was successful the second time because the maneuver freed the soft tissue structures from the contiguous impingement in the metatarsophalangeal joints by the exact reversal of the mode of injury using simultaneous application of the maneuver to all the lesser metatarsophalangeal joints. We encourage a trial of this modification of the closed reduction method in the emergency setting before proceeding to open reduction, because the results of closed reduction can be biologically rewarding without the risks associated with open surgical dissection. Copyright © 2016 American College of Foot and Ankle Surgeons. Published by Elsevier Inc. All rights reserved.

  19. Arthroscopic procedures and therapeutic results of anatomical reconstruction of the coracoclavicular ligaments for acromioclavicular Joint dislocation.

    PubMed

    Takase, K; Yamamoto, K

    2016-09-01

    Surgical treatment is recommended for type 5 acromioclavicular joint dislocation on Rockwood's classification. We believe that anatomic repair of the coracoclavicular ligaments best restores the function of the acromioclavicular joint. We attempted to correctly reconstruct the anatomy of the coracoclavicular ligaments under arthroscopy, and describe the minimally invasive arthroscopic procedure. There were 22 patients; mean age at surgery, 38.1 years. Mean time to surgery was 13.2 days. Mean follow-up was 3 years 2 months. The palmaris longus tendon was excised from the ipsilateral side to replace the conoid ligament, while artificial ligament was used for reconstructing the trapezoid ligament. Both ligament reconstructions were performed arthroscopically. No temporary fixation of the acromioclavicular joint was performed. On postoperative radiographic evaluation, 4 patients showed subluxation and 2 showed dislocation of the acromioclavicular joint; the other 16 patients had maintained reduction at the final consultation. MR images 1year after surgery clearly revealed the reconstructed ligaments in 19 patients. Only 1 patient showed osteoarthritis of the acromioclavicular joint. Although it requires resection of the ipsilateral palmaris longus for grafting, we believe that anatomic reconstruction of both coracoclavicular ligaments best restores the function of the acromioclavicular joint. 4. Copyright © 2016 Elsevier Masson SAS. All rights reserved.

  20. Congenital joint dislocations caused by carbohydrate sulfotransferase 3 deficiency in recessive Larsen syndrome and humero-spinal dysostosis.

    PubMed

    Hermanns, Pia; Unger, Sheila; Rossi, Antonio; Perez-Aytes, Antonio; Cortina, Hector; Bonafé, Luisa; Boccone, Loredana; Setzu, Valeria; Dutoit, Michel; Sangiorgi, Luca; Pecora, Fabio; Reicherter, Kerstin; Nishimura, Gen; Spranger, Jürgen; Zabel, Bernhard; Superti-Furga, Andrea

    2008-06-01

    Deficiency of carbohydrate sulfotransferase 3 (CHST3; also known as chondroitin-6-sulfotransferase) has been reported in a single kindred so far and in association with a phenotype of severe chondrodysplasia with progressive spinal involvement. We report eight CHST3 mutations in six unrelated individuals who presented at birth with congenital joint dislocations. These patients had been given a diagnosis of either Larsen syndrome (three individuals) or humero-spinal dysostosis (three individuals), and their clinical features included congenital dislocation of the knees, elbow joint dysplasia with subluxation and limited extension, hip dysplasia or dislocation, clubfoot, short stature, and kyphoscoliosis developing in late childhood. Analysis of chondroitin sulfate proteoglycans in dermal fibroblasts showed markedly decreased 6-O-sulfation but enhanced 4-O-sulfation, confirming functional impairment of CHST3 and distinguishing them from diastrophic dysplasia sulphate transporter (DTDST)-deficient cells. These observations provide a molecular basis for recessive Larsen syndrome and indicate that recessive Larsen syndrome, humero-spinal dysostosis, and spondyloepiphyseal dysplasia Omani type form a phenotypic spectrum.

  1. [Operative treatment of sacroiliac joint fracture and dislocation in Tile C pelvic fracture with Colorado 2 system].

    PubMed

    Liu, Shuping; Zhou, Qing; Liu, Yuehong; Chen, Xi; Zhou, Yu; Zhang, Desheng; Fang, Zhi; Xu, Wei

    2011-12-01

    To explore the effectiveness of Colorado 2 system in the stability reconstruction of sacroiliac joint fracture and dislocation in Tile C pelvic fracture. Between February 2009 and January 2011, 8 cases of Tile C pelvic fracture were treated with Colorado 2 system. There were 3 males and 5 females with an average age of 34.4 years (range, 22-52 years). Fractures were caused by traffic accident in 3 cases, by falling from height in 3 cases, and by crash of heavy object in 2 cases. According to Tile classification, 5 cases were classified as C1-2, 2 cases as C1-3, and 1 case as C2. The time between injury and operation was 5-10 days (mean, 7 days). After skeletal traction reduction, Colorado 2 system was used to fix sacroiliac joint, and reconstruction plate or external fixation was selectively adopted. The postoperative X-ray films showed that the reduction of vertical and rotatory dislocation was satisfactory, posterior pelvic ring achieved effective stability. All the incisions healed by first intention, and no blood vessel or nerve injury occurred. Eight patients were followed up 6-24 months (mean, 12 months). No loosening or breakage of internal fixation was observed and no re-dislocation of sacroiliac joint occurred. The bone healing time was 6-12 months (mean, 9 months). According to Majeed's functional criterion, the results were excellent in 5 cases, good in 2 cases, and fair in 1 case at last follow-up. Colorado 2 system could provide immediate stability of pelvic posterior ring and good maintenance of reduction effect, which is an effective method in the therapy of sacroiliac joint fracture and dislocation in Tile C pelvic fracture.

  2. Treatment of peroneal tendon dislocation and coexisting medial and lateral ligamentous laxity in the ankle joint.

    PubMed

    Ziai, Pejman; Sabeti-Aschraf, Manuel; Fehske, Kai; Dlaska, Constantin E; Funovics, Philipp; Wenzel, Florian; Graf, Alexandra; Buchhorn, Tomas

    2011-06-01

    Acute dislocation of the peroneal tendon is caused by massive combined flexion-torsion trauma supported by preexisting ligamentous laxity of the ankle joint. This study aimed to investigate the clinical outcome of combined treatment of peroneal tendon dislocation and lateral and medial ligamentous laxity. Between 2005 and 2007, forty-two patients with peroneal tendon dislocation and coexisting ligamentous laxity were treated. The superior extensor retinaculum was reconstructed using anchor technique and periosteal flap repair, whereas the preexisting ligamentous laxity with regard to the extensor inferior retinaculum was addressed using anchor reconstruction. All patients underwent arthroscopy prior to surgery. Thirty-eight of a total of 42 patients (aged 17-31) completed the 24-month follow-up. Clinical and arthroscopic examination was accomplished consistently by always the same two surgeons. Postoperative follow-up comprised clinical evaluation after 3, 6, 12 and 24 months. Clinical results showed a significant (P<0.0001) increase in the AOFAS-Hindfoot Score as an often used but not validated outcome measure, as well as a significant decrease in the Visual Analogue Scale and in the internal and external rotation, after 3 months. The clinical outcome was confirmed at the 6-, 12- and 24-months measuring points. No dislocation of the peroneal tendon recurred within the 24-month follow-up. Subjective patient satisfaction was stated as high. Combined treatment of peroneal tendon dislocation and coexisting lateral and medial ligamentous laxity in the ankle joint following arthroscopy results in good clinical outcome and high patient satisfaction. Case series, Level IV.

  3. [Complications of treatment of acromioclavicular joint dislocation and unstable distal clavicular fracture with clavicular hook plate].

    PubMed

    Zhu, Yi-Yong; Cui, Heng-Yan; Jiang, Pan-Qiang; Wang, Jian-Liang

    2013-11-01

    To investigate the causes and prevention of the complications about treatment of acromioclavicular joint dislocation (Tossy III) and unstable distal clavicular fracture (Neer II) with clavicular hook plate. From January 2001 to December 2011, 246 patients with acromioclavicular joint dislocation (Tossy III) and 222 patients with unstable distal clavicular fracture (Neer II) were treated with acromioclvicular hook plate fixation,including 348 males and 120 females with an average age of 45.4 years old ranging from 21 to 80 years old. The mean time from injury to operation was 30.8 hours (ranged from 1 h to 15 d). All patients had normal shoulder function before injury. According to Karlsson evaluation standard, the cases with excellent and good function of the shoulder joint were regarded as the normal group, and the cases with poor function of shoulder joint as the abnormal group. The comparison of the range of forward flexion,backward stretch, adduction, abduction and elevation of shoulder joints between two groups was performed. The data of impingement, subacromial osteolysis, acromioclavicular arthritis, clavicular stress fracture, downward acromioclavicular joint subluxation, hook cut-out and hook break were summarized. All patients were followed up from 8 to 48 months with an average of 12.5 months. The results were excellent in 308 cases,good in 76,and poor in 84 according to Karlsson evaluation. The excellent and good rate was 82.1%. The difference of the range of forward flexion, backward stretch, adduction, abduction and elevation of shoulder joints between two groups had a statistically significant difference (P < 0.01). Among 84 poor cases, there were 41 (8.76%) in acromial impingement or inadequate place of plate hook, 12 (2.56%) with subacromial osteolysis or/and bursitis, 10 (2.14%) with acromioclavicular arthritis or painful shoulder caused by delayed dirigation,7 (1.50%) with clavicular stress fracture or interal plate upward, 6 (1.28%) with

  4. Coplanar three-beam interference and phase edge dislocations

    NASA Astrophysics Data System (ADS)

    Patorski, Krzysztof; SłuŻewski, Łukasz; Trusiak, Maciej; Pokorski, Krzysztof

    2016-12-01

    We present a comprehensive analysis of grating three-beam interference to discover a broad range of the ratio of amplitudes A of +/-1 diffraction orders and the zero order amplitude C providing phase edge dislocations. We derive a condition A/C > 0.5 for the occurrence of phase edge dislocations in three-beam interference self-image planes. In the boundary case A/C = 0.5 singularity conditions are met in those planes (once per interference field period), but the zero amplitude condition is not accompanied by an abrupt phase change. For A/C > 0.5 two adjacent singularities in a single field period show opposite sign topological charges. The occurrence of edge dislocations for selected values of A/C was verified by processing fork fringes obtained by introducing the fourth beam in the plane perpendicular to the one containing three coplanar diffraction orders. Two fork pattern processing methods are described, 2D CWT (two-dimensional continuous wavelet transform) and 2D spatial differentiation.

  5. Clinical therapeutic effects of AO/ASIF clavicle hook plate on distal clavicle fractures and acromioclavicular joint dislocations.

    PubMed

    Dou, Qingjun; Ren, Xiaofeng

    2014-07-01

    The aim of this study was to evaluate the security and effectiveness of AO/ASIF clavicle hook plate in the treatment of distal clavicle fractures and acromioclavicular joint dislocations. One hundred patients with distal clavicle fractures and acromioclavicular joint dislocations who were admitted in our hospital from January 2012 to January 2013 were selected as the study subjects. They were then randomly divided into a control group and an observation group (n=50). The observation group was treated with AO/ASIF clavicle hook plates, and the control group was treated with Kirschner-wire tension bands. The outcomes were recorded and compared. The JOA scores of the two groups were similar before surgery (P>0.05). The two groups both had obviously increased JOA scores in the postoperative 6th and 12th weeks, and the score in the postoperative 12th week was higher. There were statistically significant intra-group differences (P<0.05). The postoperative 6th-week and 12th-week JOA scores of the observation group were (83.2±1.8) and (97.4±1.5) respectively, and those of the control group were (71.6±2.2) and (82.3±2.6) respectively, with statistically significant inter-group differences (P<0.05). Significantly more patients in the observation group (100%) were evaluated as excellent or good outcomes after fixation than those in the control group (60%). After removal of the surgical apparatus, the recurrence rates of bone fracture and joint dislocation in the observation group were significantly lower than those of the control group (P<0.05). AO/ASIF clavicle hook plate functioned more effectively than Kirschner-wire tension band in clinical treatment of distal clavicle fractures and acromioclavicular joint dislocations. The former protocol enjoyed small incisions, firm fixation and early shoulder mobility. Therefore, it is a safe and effective surgical method that is worthy of being widely applied in clinical practice.

  6. Clinical Effect of Acute Complete Acromioclavicular Joint Dislocation Treated with Micro-Movable and Anatomical Acromioclavicular Plate

    PubMed Central

    Liu, Qingjun; Miao, Jianyun; Lin, Bin; Guo, Zhimin

    2012-01-01

    Objectives: We evaluated the long-term clinical results of acute complete acromioclavicular dislocations treated with micro-movable and anatomical acromioclavicular plate. Methods: Open reduction and internal fixation was performed using the MAAP in 16 patients (10 males, 6 females; mean age 36 years; range16 to 63 years) with acute complete acromioclavicular joint dislocation. Radiographic evaluations were routinely conducted every 3 weeks until 3 months postoperatively. The MAAP were removed under local anesthesia after 3 months postoperatively. We evaluated the functional results by using the constant scoring system and radiological results in the last follow-up time. The mean follow up was 26 months (range 16 to 38 months). Results: The mean Constant score was 94 (range, 78 to 100). The results were excellent in 12 patients (75.0%), good in 3 patients (18.8%) and satisfactory in 1patient (6.2%). Three patients with scores of 80 to 90 had mild pain during activity, but have not affected the shoulder range of motion. One patient has both some pain and limited range of motion of shoulder joint. All patients but one have returned to their preoperative work without any limitations. Compared to the contralateral side, radiography showed anatomical reposition in the vertical plane in 14 cases, slight loss of reduction in 2 older patients. Conclusion: We recommend the MAAP fixation for surgical treatment of acute complete acromioclavicular joint dislocation as it could provide satisfactory shoulder functions and clinical results, with lower complication rate. However, it is necessary to continue to observe the clinical effects of this fixation technique. PMID:23091410

  7. Iatrogenic arteriovenous fistula of the superficial temporal artery after manual reduction of temporomandibular joint dislocation.

    PubMed

    Takeuchi, Satoru; Takasato, Yoshio

    2011-09-01

    A 33-year-old man fell from a height and was referred to our hospital. Physical examination showed a swelling in the left preauricular region without laceration. No thrill or bruit was detected at this time. A face x-ray and a computed tomographic scan showed a left temporomandibular joint (TMJ) dislocation, Le Fort I fractures, and a mandibular body fracture. Left TMJ dislocation was treated by manual reduction. Two days after admission, a swelling in the left preauricular region progressed, with thrill and bruit. Left external carotid artery angiograms showed an arteriovenous fistula with a dilated pouch near the left TMJ. The fistula was fed by the left superficial temporal artery and drained into the left superficial temporal vein. The fistula was successfully embolized using Tornado coils. This is the first case of an arteriovenous fistula of the superficial temporal artery after manual reduction of TMJ dislocation.

  8. Secondary infection of haematoma following closed acromioclavicular joint dislocation

    PubMed Central

    Dupley, Leanne; Berg, Andrew James; Mohil, Randeep

    2016-01-01

    An unusual case of a patient presenting with a large infected haematoma following a traumatic grade II acromioclavicular joint dislocation is reported. Diagnosis of this rare complication, of an otherwise common self-limiting injury, was delayed until 19 days postinjury despite several presentations during this time with worsening swelling and pain. The patient was found to have significant tissue destruction by the time washout was performed and required multiple procedures to treat the infection. This case highlights the need for a high index of suspicion for complications, even following common self-limiting injuries, when patients represent with symptoms that do not fit the usual natural history of the condition, particularly if they have risk factors for bleeding and infection. PMID:26786526

  9. Management of Chronic Recurrent Dislocation of Temporomandibular Joint Using 'U' Shaped Graft: A New Restrictive Technique.

    PubMed

    Gadre, Kiran; Singh, Divya; Gadre, Pushkar; Halli, Rajshekhar

    2017-06-01

    Numerous procedures have been described for the treatment of chronic recurrent dislocation of the temporo-mandibular joint (TMJ), either in the form of enhancement or restriction of the condylar movement, with their obvious merits and demerits. We present a new technique of using U shaped iliac bone graft to restrict the condylar movement and its advantages over the conventional techniques.We have used this technique successfully in 8 cases where Dautrey's procedure had failed with follow up period of 2 years. No patient complained of recurrent dislocation postoperatively. This a very simple and effective technique where other procedures have failed.

  10. 3-D sonography for diagnosis of disk dislocation of the temporomandibular joint compared with MRI.

    PubMed

    Landes, Constantin A; Goral, Wojciech A; Sader, Robert; Mack, Martin G

    2006-05-01

    This study determines the value of three-dimensional (3-D) sonography for the assessment of disk dislocation of the temporomandibular joint (TMJ). Sixty-eight patients (i.e.,136 TMJ) with clinical dysfunction were examined by 272 sonographic 3-D scans. An 8- to 12.5-MHz transducer, angulated by step-motor, was used after picking a volume box on 2-D scan; magnetic resonance imaging followed immediately. Every TMJ was scrutinized in closed- and open-mouth position for normal or dislocated disk position. Fifty-three patients had complete data sets, i.e., 106 TMJ, 212 examinations. Sonographic examination took 5 min, with 74% specificity (62% closed-mouth; 85% open-mouth); sensitivity 53% (62/43%); accuracy 70% (62/77%); positive predictive value 49% (57/41%); and negative predictive value 77% (67/86%). This study encourages more research on the diagnostic capacity of 3-D TMJ sonography, with the advantage of multidimensional joint visualization. Although fair in specificity and negative predictive value, sensitivity and accuracy may ameliorate with future higher-sound frequency, real-time 3-D viewing and automated image analysis.

  11. Arthroscopic fixation of acute acromioclavicular joint disruption with TightRope™: Outcome and complications after minimum 2 (2-5) years follow-up.

    PubMed

    Zhang, Li-Feng; Yin, Bo; Hou, Su; Han, Bing; Huang, De-Fa

    2017-01-01

    To evaluate the midterm results of arthroscopic reconstruction of acute acromioclavicular (AC) joint disruption using TightRope™ system. We retrospectively assess the results of 24 patients of acute AC joint dislocation who were operated using TightRope system. Constant and University of California, Los Angeles (UCLA) scores and coracoclavicular distance were calculated pre- and postoperatively. Data was entered into MS excel and analyzed using the SPSS version 17. The mean follow-up was 39.45 months. Constant and UCLA scores were significantly increased postoperatively. Six patients had partial loss of reduction within 3-6 months and two patients had a failure of construct. Constant score was significantly lower in these patients. TightRope reconstruction of the AC joint is a reproducible and safe alternative to many other techniques of AC joint reconstruction. Early subluxation remains a concern and may reflect the need for technique modification.

  12. Clavicular hook plate for grade-III acromioclavicular dislocation.

    PubMed

    Steinbacher, Gilbert; Sallent, Andrea; Seijas, Roberto; Boffa, Juan Manuel; Espinosa, Wenceslao; Cugat, Ramón

    2014-12-01

    To review the outcomes of clavicular hook plate fixation for grade-III acromioclavicular (AC) dislocation in young athletes. Medical records of 14 male and 5 female athletes aged 18 to 49 (mean, 29) years who underwent fixation with a 3.5-mm-thick, 15-mm-long clavicular hook plate for acute grade-III AC dislocation were reviewed. The visual analogue score for pain and the Constant shoulder score were assessed. The mean follow-up was 4.2 years. The mean visual analogue score for pain was 1.8 (range, 1-3). The Constant shoulder score was excellent (≥ 90) in 14 patients and good (83-89) in 5 patients. All patients achieved range of motion equal to that of the contralateral side at week 5. Sports activities were resumed by month 6 at the latest. The clavicular hook plate for grade- III AC dislocation enables quick return to sports activities and achieves good-to-excellent functional outcome.

  13. Management of irreducible unilateral facet joint dislocations in subaxial cervical spine: two case reports and a review of the literature.

    PubMed

    Zhou, Yu; Zhou, Zhenyu; Liu, Lifeng; Cao, Xuecheng

    2018-03-21

    Skeletal and soft tissue damage are often associated with unilateral facet dislocations, which undoubtedly lead to instability of the spine and further increase difficulties in cervical reduction. This type of irreducible facet dislocation is usually accompanied with potential catastrophic consequences including neurological deficit and severe disability. Therefore, a consistent and evidence-based treatment plan is imperative. The literature regarding the management of traumatic unilateral locked cervical facet dislocations was reviewed. Two patient cases (a 30-year-old Asian man and a 25-year-old Asian woman) who suffered irreducible cervical facet dislocations were presented. These two patients received surgical treatments including posterior reduction by poking facet joints, adjacent spinous process fixation by wire rope banding, anterior plate fixation, and intervertebral fusion after the failure of skull traction and closed reduction. At the postoperative 24-month follow-up, intervertebral fusion was achieved and our patients' neurological status improved based on the American Spinal Injury Association scale, compared with their preoperative status. Unilateral facet joint dislocations of subaxial cervical spine are difficult to reduce when complicated with posterior facet fractures or ligamentous injury. Magnetic resonance imaging can be beneficial for identifying ventral and dorsal compressive lesions, as well as ligamentous or capsule rupture. The combination of posterior reduction and anterior fixation with fusion has advantages in terms of clinical safety, ease of operation, and less iatrogenic damage.

  14. Open Dislocation of the High Ankle Joint After Fibular Graft Harvesting.

    PubMed

    Anđelković, Slađana Z; Vučković, Čedo Đ; Palibrk, Tomislav D; Milutinović, Suzana M; Bumbaširević, Marko Ž

    2015-01-01

    The free microvascular fibula and soft tissue transfer has become a widely used method for reconstruction of different regions. Donor site morbidity for free fibula microvascular flaps has generally been reported to be low, or at least acceptable. We describe the case of a patient who underwent vascularized free fibula graft harvest for mandibular reconstruction. After 21 months, he had sustained an open dislocation of the left high ankle joint during recreational sports activity. We did not found such case in the published data. Copyright © 2015 American College of Foot and Ankle Surgeons. Published by Elsevier Inc. All rights reserved.

  15. [Development and clinical application of a new type of anatomical locking plate for sternoclavicular joint fracture and dislocation].

    PubMed

    Sun, Yuanlin; Yang, Yunkang; Ge, Jianhua; Yang, Kun; Xiang, Feifan; Zhou, Ju; Liang, Jie

    2018-03-01

    To report a new type of anatomical locking plate for sternocalvicular joint, and investigate its effectiveness in treatment of sternoclavicular joint fracture and dislocation. A new type of anatomical locking plate for sternoclavicular joint was developed, which accorded with the anatomical features and biomechanical characteristics of Chinese sternoclavicular joint. By adopting the method of clinical randomized controlled study, 32 patients with the sternoclavicular joint fracture and dislocation who met the selection criteria between June 2008 and May 2015 were randomly divided into groups A and B ( n =16), and the patients were treated with new anatomic locking plate and distal radial T locking plate internal fixation, respectively. There was no significant difference between 2 groups in gender, age, injured side, body mass index, cause of injury, type of injury, the time from injury to operation, and preoperative Rockwood grading score ( P >0.05). The operation time, intraoperative blood loss, incision length, hospitalization time, and postoperative complications in 2 groups were recorded, and the effectiveness was evaluated by Rockwood grading score. The operations of 2 groups completed successfully. The operation time, intraoperative blood loss, and hospitalization time in group A were significantly less than those in group B ( P <0.05), but there was no significant difference in the incision length between 2 groups ( t =0.672, P =0.507). All the patients were followed up 18-30 months (mean, 24 months). In group A, there were 1 case of sternoclavicular joint pain and 2 cases of wound infection; in group B, there were 1 case of sternoclavicular joint pain, 1 case of internal fixation loosening, and 1 case of sternoclavicular joint re-dislocation; there was no significant difference in complication incidence between 2 groups ( P =1.000). The Rockwood grading scores at each time point after operation in 2 groups were significantly higher than those before

  16. Loss of reduction and complications of coracoclavicular ligament reconstruction with autogenous tendon graft in acute acromioclavicular dislocations.

    PubMed

    Choi, Nam Hong; Lim, Seok Min; Lee, Sang Young; Lim, Tae Kang

    2017-04-01

    This study was conducted to report loss of reduction and complications after single-tunnel coracoclavicular (CC) ligament reconstruction with autogenous semitendinosus tendon graft for acute acromioclavicular (AC) joint dislocations. This retrospective study included patients with acute, unstable AC dislocations (surgery within 6 weeks after trauma). We excluded patients with chronic injury and distal clavicle fractures with CC ligaments disruption. We measured the CC distance on anteroposterior radiographs of both clavicles, preoperatively, immediately postoperatively, and at the final follow-up visit. We evaluated clinical outcomes using the American Shoulder and Elbow Surgeons Shoulder Assessment and the University of California, Los Angeles Shoulder Rating Scale scores and perioperative complications. There were 30 patients (27 men and 3 women) with mean age of 41 years (range, 19-70 years). The mean follow-up period was 31 months (range, 12-186 months). Mean CC distance was 15.5 ± 3.7 mm (84% ± 14% of the contralateral shoulder) preoperatively, 8.9 ± 2.6 mm (9% ± 40%) immediately postoperatively (P < .001), and 10.6 ± 3.3 mm (24% ± 39%) at the final assessment (P < .001), showing an increase of the CC distance during the follow-up. Loss of reduction (defined as >25% increase of CC distance) developed in 14 patients (47%), and complications occurred in 6 patients (20%), including 3 distal clavicle fractures through the tunnel. Final clinical scores were significantly lower in patients with complications (27 vs. 33 of the University of California, Los Angeles assessment [P < .001] and 81 vs. 95 of the American Shoulder and Elbow Surgeons Shoulder assessment [P < .001]). In acute AC joint dislocation, single-tunnel CC ligament reconstruction using autogenous tendon graft resulted in loss of reduction rate of 47% and a complication rate of 20%. The development of complications adversely affected clinical outcomes

  17. A variant neglected Type IIIA dorsal dislocation of first metatarsophalangeal joint. A case report.

    PubMed

    Ainhoa, Toro-Ibarguen; Moreno-Beamud, Jose Alberto; Martínez-Leocadio, Miguel-Ángel; Candel-García, Luciano; Díaz-Martín, Andrés; Delgado-Díaz, Emilio

    2015-03-01

    We present a rare injury consisting of a neglected, irreducible, dislocation of the first metatarsophalangeal joint that was diagnosed 4 months after the injury. An open reduction was necessary from the beginning. Patient returned to full activity without pain or disability, so a good prognosis despite the delayed diagnosis was achieved. We are unaware of previous reports in the literature describing this unusual variant. Copyright © 2014 European Foot and Ankle Society. Published by Elsevier Ltd. All rights reserved.

  18. Traumatic ipsilateral multiple open metatarsal and calcaneal fractures with first metatarsophalangeal joint dislocation: a case report.

    PubMed

    Ozkan, Namik Kemal; Unay, Koray; Cift, Hakan; Eceviz, Engin; Ozkan, Korhan

    2010-06-01

    A 17-year-old man fell from a height of 10 m onto his right forefoot and sustained ipsilateral calcaneal, comminuted cuboid, and second, third, and fourth metatarsal neck fractures and first metatarsophalangeal joint open dislocation. This report discusses this rare injury. The authors believe that initial debridement with immediate surgical fixation and reduction with appropriate antibiotic treatment saved the patient's extremity.

  19. Chronic Irreducible Anterior Dislocation of the Shoulder without Significant Functional Deficit.

    PubMed

    Chung, Hoejeong; Yoon, Yeo-Seung; Shin, Ji-Soo; Shin, John Junghun; Kim, Doosup

    2016-09-01

    Shoulder dislocation is frequently encountered by orthopedists, and closed manipulation is often sufficient to treat the injury in an acute setting. Although most dislocations are diagnosed and managed promptly, there are rare cases that are missed or neglected, leading to a chronically dislocated state of the joint. They are usually irreducible and cause considerable pain and functional disability in most affected patients, prompting the need to find a surgical method to reverse the worsening conditions caused by the dislocated joint. However, there are cases of even greater rarity in which chronic shoulder dislocations are asymptomatic with minimal functional or structural degeneration in the joint. These patients are usually left untreated, and most show good tolerance to their condition without developing disabling symptoms or significant functional loss over time. We report on one such patient who had a chronic shoulder dislocation for more than 2 years without receiving treatment.

  20. Dislocation: First Aid

    MedlinePlus

    ... or a collision during contact or high-speed sports. Dislocation usually involves the body's larger joints. In adults, the most common site of the injury is the shoulder. In children, it's the elbow. ...

  1. Prevalence and pattern of glenohumeral injuries among acute high-grade acromioclavicular joint instabilities.

    PubMed

    Pauly, Stephan; Kraus, Natascha; Greiner, Stefan; Scheibel, Markus

    2013-06-01

    With increasing numbers of arthroscopically assisted acromioclavicular (AC) joint stabilization procedures has come an increase in reports of concomitant glenohumeral injuries among AC joint separations. The aim of the present study was to evaluate the prevalence, pattern, and cause of glenohumeral pathologies among a large patient population with acute high-grade AC joint instability. A total of 125 patients (13 women, 112 men) with high-grade AC joint dislocation (6 Rockwood II; 119 Rockwood V) underwent diagnostic glenohumeral arthroscopy before AC joint repair. Pathologic lesions were evaluated for acute or degenerative origin and, if considered relevant, treated all-arthroscopically. Concomitant glenohumeral pathologies were found in 38 of 125 patients (30.4%). Analysis of pathogenesis distinguished different patterns of accompanying injuries: acute intra-articular lesions, related to the recent shoulder trauma, were found in 9 patients (7.2%), degenerative lesions, considered to be unrelated to the recent trauma, were found in 18 (14.4%), and 11 (8.8%) had an unclear traumatic correlation (intermediate group). Within the acute and the degenerative group, affected structures were predominantly partial, articular-sided tears of the anterosuperior rotator cuff, including instabilities of the pulley complex, followed by pathologies of the long head of the biceps and superior labrum anteroposterior lesions. The intermediate group presented mainly with articular-sided partial tears of the subscapularis tendon. This prospective study showed a high prevalence (30%) of concomitant glenohumeral pathologies, of which some indicate additional surgical therapy and could be missed by an isolated open AC repair. Hence, the arthroscopic approach for AC joint stabilization allows for the diagnosis and treatment of associated intra-articular pathologies. Copyright © 2013 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Mosby, Inc. All rights reserved.

  2. Influence of age on the outcome of single stage reconstructive surgery for congenital dislocation of the hip joint.

    PubMed

    Bhatti, Anisuddin; Jamali, A R; Mehboob, Ghulam

    2009-01-01

    This study was conducted to assess the effect of age on the ultimate outcome measures following single stage surgical procedure of soft tissue release, relocation, capsulorrhaphy, femoral shortening with varus/derotation osteotomy and pelvic osteotomy. A case series. The study with two groups of pretest-posttest design was conducted at Department of Orthopaedic Surgery, Jinnah Postgraduate Medical Centre (JPMC), Karachi, from 1993 to January 2008. Patients included were having neglected, congenital dislocation of the hip joint, aged over 3 years. Patients with failed previous surgery, paralytic, teratological, traumatic or septic dislocations and patients with less than 5 years follow-up were excluded from the study. The patients were divided into two groups, 3-7 years (37 hip joints) and over 7 years (13 hip joints). The single stage surgical procedure of open relocation, femoral shortening/derotation/ varus osteotomy and pelvic osteotomy was the dependent variable; whereas, the final clinico-radiological results based upon Tonnis grading, Severin's clinical/radiological grading, Klisic's overall rating and acetabular index were the independent variables of the study. Pre- and postoperative data was assessed for overall improvement and the difference in outcome measures between the two age groups. Significant overall improvement on all parameters was achieved after surgery. When results were compared between two age groups, there was no significant difference in the final outcome as per Tonnis grading and Severin's clinical typing as modified by Gibson (97.3% versus 84.4% normal hip joints or Tonnis grade 1 and 78.37% versus 53.85% Severin's type 1) but the results based upon Severin's radiological grading (62.16% versus 15.38%) and Klisic's overall rating (62.16% versus 15.38%) were significantly better in 3-7 years as compared to those over 7 years. There was no significant difference between the two age groups when compared for improvement in acetabular index

  3. [Nuclear magnetic tomography in shoulder dislocation].

    PubMed

    Runkel, M; Kreitner, K F; Wenda, K; Rudig, L; Degreif, J; Grebe, P

    1993-03-01

    Sixty-two patients with anterior shoulder dislocations were examined by magnetic resonance imaging (MRI). After a primary dislocation, 30 patients showed 23 (77%) tears of the glenoid labrum, 13 (45%) anterior-inferior separation of the capsula, 24 (83%) Hill-Sachs lesions, 6 fractures of the greater tuberosity and 4 glenoid rim fractures. Thirty-two patients with recurrent shoulder dislocation had 14 (44%) tears and 15 (47%) defects of the glenoid labrum, 16 (50%) anterior-inferior separation of the capsula, 28 (88%) Hill-Sachs lesions and 3 glenoid rim fractures. MRI permits complete non-invasive documentation of glenohumeral instability if joint effusion is present. In the absence of joint effusion, diagnostic accuracy can be improved by application of a contrast medium.

  4. [Treatment of complete acromioclavicular joint dislocation with transfer of the medial half of the coracoacromial ligament to reconstruct the coracoclavicular ligament].

    PubMed

    Dong, Wen-Wei; Shi, Zeng-Yuan; Liu, Zheng-Xin; Mao, Hai-Jiao

    2015-04-01

    To explore the operation methods and clinical effects of transfer of the medial half of the coracoacromial ligament to reconstruct the coracoclavicular ligament in treating complete acromioclavicular joint dislocation. From January 2006 to June 2012,26 patients with acute complete acromioclavicular joint dislocation underwent surgery. Transfer of the medial half of the coracoacromial ligament to reconstruct the coracoclavicular ligament, additional clavical hoot plate and Kirschner wires fixation, were performed in all the patients. Among the patients, 18 patients were male and 8 patients were female, with an average age of 36.7 years old (ranged from 25 to 51 years). The duration from injury to operation was from 3 to 12 days with an average of 5 days. According to the Rockwood classification, 4 cases were grade III and 22 cases were grade V . Clinical manifestation included local swelling, tenderness with snapping, limitation of shoulder joint motion. In preoperative bilateral shoulder joint X-rays, the injured coracoclavicular distance was (16.2 ± 5.0) mm which was significantly wider than that of uninjured sides (7.6 ± 1.0) mm. Clinical results were evaluated according to X-rays and Constant-Murley score. All incisions obtained primary healing after operation without complication of infection, internal fixation breakage, redislocation. All the patients were followed up from 12 to 30 months with an average of 18 months. Kirschner wires and internal fixation plate were removed at 1 month and 8-10 months after operation, respectively. At final follow-up, the motion of shoulder joint recovered to normal and a no pain joint was obtained. According to Constant-Murley score, 24 cases got excellent results and 2 cases good. There was no significant difference after operation between the injured coracoclavicular distance and the uninjured contralateral side [(7.7 ± 1.2) mm vs (7.6 ± 1.0) mm), P > 0.05]. Transfer of the medial half of the coracoacromial ligament to

  5. Arthroscopic treatment of acute acromioclavicular dislocations using a double button device: Clinical and MRI results.

    PubMed

    Loriaut, P; Casabianca, L; Alkhaili, J; Dallaudière, B; Desportes, E; Rousseau, R; Massin, P; Boyer, P

    2015-12-01

    Arthroscopic treatment of acute grade 3 and 4 acromioclavicular dislocation is controversial, due to the risk of recurrence and of postoperative reduction defect. The purpose of the present study was to investigate whether the healing of the acromioclavicular (AC) and coracoclavicular (CC) ligaments and the accurate 3D positioning parameters of the AC joint using MRI were correlated with satisfactory functional outcome. Thirty-nine patients were enrolled from 2009 to 2011 and managed arthroscopically by CC lacing using a double-button device. Clinical assessment included the Shoulder and Hand (QuickDash) score, Constant-Murley score and visual analog scale (VAS) for residual pain. Time and rate to return to work and return to sport were assessed according to type of sport and work. Postoperative complications were recorded. Radiological examination consisted of anteroposterior clavicle and lateral axillary radiographs. AC ligament healing and 3D joint congruency were assessed on MRI and correlated to the clinical results. Mean patient age was 35.7 years (range, 20-55). Mean follow-up was 42.3±10.6 months (range, 24-60). At final follow-up, mean QuickDash score, Constant score and VAS were respectively 1.7±4 (range, 0-11), 94.7±7.3 (range, 82-100) and 0.5±1.4 (range, 0-2). Thirty-five (90%) patients were able to resume work, including heavy manual labor, and sport. Radiology found accurate 3D joint congruency in 34 patients (87%) and CC and AC ligament healing in 36 (93%). Complications included reduction loss at 6 weeks in 3 patients, requiring surgical stabilization. Satisfactory functional results were associated with accurate AC joint congruency in the coronal and axial planes (P<0.05) and good AC and CC ligament healing (P<0.04). An initial 25% reduction defect in the coronal plane was not associated with poor functional results (P=0.07). Arthroscopic treatment by CC lacing satisfactorily restored ligament and joint anatomy in the present series. These

  6. Comparison of the Tight Rope Technique and Clavicular Hook Plate for the Treatment of Rockwood Type III Acromioclavicular Joint Dislocation.

    PubMed

    Cai, Leyi; Wang, Te; Lu, Di; Hu, Wei; Hong, Jianjun; Chen, Hua

    2018-06-01

    Acromioclavicular joint dislocation is one of the most common shoulder problems and may lead to instability or degenerative changes. The aim of this study was to compare the clinical outcomes of the Tight Rope system and clavicular hook plate for Rockwood type III acromioclavicular joint dislocation in adults. This was a prospective, randomized study in a hospital setting. From January 2012 to December 2014, 69 patients with type III injury were reviewed. Patients were randomly divided into two groups: Group A was treated using the TightRope system and Group B with the clavicular hook plate. All participants were followed up for 12 months. Clinical outcomes, radiological results and postoperative complications were recorded. The length of incision was significantly shorter in Goup A than that in Group B. The blood loss of surgery was significantly less in the Group A. Significant difference could be found between the two groups regarding the Visual Analogue Scale scores one day after surgery, at the 3 and 12 months follow-up. There were no differences according to the improvement of the Constant-Murley score and the coracoclavicular distance between the groups. The two groups have similar clinical and radiological outcomes. Both treatments could relieve the pain of dislocation, improve the function of Acromioclavicular joint and rectify the coracoclavicular distance measured in plain films. However, the TightRope system exhibited some advantages in terms of length of incision, blood loss of surgery, the pain postoperatively and no need for a second surgery.

  7. Internal friction and dislocation collective pinning in disordered quenched solid solutions

    NASA Astrophysics Data System (ADS)

    D'Anna, G.; Benoit, W.; Vinokur, V. M.

    1997-12-01

    We introduce the collective pinning of dislocations in disordered quenched solid solutions and calculate the macroscopic mechanical response to a small dc or ac applied stress. This work is a generalization of the Granato-Lücke string model, able to describe self-consistently short and long range dislocation motion. Under dc applied stress the long distance dislocation creep has at the microscopic level avalanche features, which result in a macroscopic nonlinear "glassy" velocity-stress characteristic. Under ac conditions the model predicts, in addition to the anelastic internal friction relaxation in the high frequency regime, a linear internal friction background which remains amplitude-independent down to a crossover frequency to a strongly nonlinear internal friction regime.

  8. Spinopelvic Fixation of Sacroiliac Joint Fractures and Fracture-Dislocations: A Clinical 8 Years Follow-Up Study.

    PubMed

    Sobhan, Mohammad R; Abrisham, Seyed Mohammad J; Vakili, Mahmood; Shirdel, Saeed

    2016-10-01

    Pelvic ring injuries and sacroiliac dislocations have significant impacts on patient's quality of life. Several techniques have been described for posterior pelvic fixation. The current study has been designed to evaluate the spinopelvic method of fixation for sacroiliac fractures and fracture-dislocations. Between January 2006 and December 2014, 14 patients with sacroiliac joint fractures, dislocation and fracture-dislocation were treated by Spinopelvic fixation at Shahid Sadoughi Training Hospital, Yazd, Iran. Patients were seen in follow up, on average, out to 32 months after surgery. Computed tomographic (CT) scans of patients with sacral fractures were reviewed to determine the presence of injuries. A functional assessment of the patients was performed using Majeed's score. Patient demographics, reduction quality, loss of fixation, outcomes and complications, return to activity, and screw hardware characteristics are described. The injury was unilateral in 11 (78.5%) patients and bilateral in 3 (21.5%). Associated injuries were present in all patients, including fractures, dislocation and abdominal injuries. Lower limb length discrepancy was less than 10 mm in all patients except two. Displacement, as a measure of quality of reduction was less than 5 mm in 13 patients. The mean Majeed score was 78/100. Wound infection and hardware failure were observed in 3 (21.4%) and 1 (7.1%) cases, respectively. In this study most patients (85%) return to work postoperatively. According to the findings, spinopelvic fixation is a safe and effective technique for treatment of sacroiliac injuries. This method can obtain early partial to full weight bearing and possibly reduce the complications.

  9. OK-432 (Picibanil) sclerotherapy for recurrent dislocation of the temporomandibular joint in elderly edentulous patients: Case reports.

    PubMed

    Matsushita, Kazuhiro; Abe, Takae; Fujiwara, Toshikatsu

    2007-09-01

    Dislocation of the temporomandibular joint (TMJ) is a thorny problem not only for a patient but also a doctor. Especially for the elderly edentulous patients, it is very hard to treat the condition although there are many surgical and non-surgical procedures. We successfully treated it in two elderly edentulous patients by injection of OK-432 as a sclerosing agent.

  10. [COMPARISON OF EFFECTIVENESS BETWEEN TWO OPERATIVE TECHNIQUES OF CORACOCLAVICULAR LIGAMENT RECONSTRUCTION FOR TREATMENT OF Tossy TYPE III ACROMIOCLAVICULAR JOINT DISLOCATION].

    PubMed

    Tang, Hongwei; Gao, Sheng; Yin, Yong; Li, Yunfei; Han, Qingtian; Li, Huizhang

    2015-11-01

    To evaluate and compare the effectiveness of double Endobutton technique and suture anchor combined Endobutton plate in the treatment of Tossy type III acromioclavicular joint dislocation. Between May 2010 and March 2014, a retrospective study was preformed on 56 patients with Tossy type III acromioclavicular joint dislocation. The coracoclavicular ligament was reconstructed with double Endobutton technique in 31 cases (Endobutton group), and with suture anchor combined Endobutton plate in 25 cases (Anchor group). There was no significant difference in age, gender, injury causes, injury side, associated injury, medical comorbidities, and disease duration between 2 groups (P>0.05). The operation time, medical device expenses, postoperative complications, preoperative and postoperative Constant-Murley scores, and postoperative Karlsson grading of the injured shoulder were compared between 2 groups. The average operation time in Endobutton group was significantly greater than that in Anchor group (t = 4.285, P = 0.000); there was no significant difference in the medical device expenses between 2 groups (t = 1.555, P = 0.126). Primary healing of incision was obtained in all patients of 2 groups; no early complications of infection and skin necrosis occurred. All patients were followed up 15.6 months on average (range, 11-35 months). During follow-up, some loss of reduction and ectopic ossification in the coracoclavicular gap were observed in 1 case and 6 cases of Endobutton group, respectively. No recurrence of acromioclavicular joint dislocation, implant fixation loosening and broken, and secondary fractures occurred in the other patients. There was significant difference in the incidence of postoperative complications between 2 groups (P = 0.013). Constant-Murley scores of the injured shoulder significantly increased at 9 months after operation when compared with preoperative values in 2 groups (P < 0.05), but no significant difference was observed between 2 groups

  11. Biomechanical characteristics of hemi-hamate reconstruction versus volar plate arthroplasty in the treatment of dorsal fracture dislocations of the proximal interphalangeal joint.

    PubMed

    Tyser, Andrew R; Tsai, Michael A; Parks, Brent G; Means, Kenneth R

    2015-02-01

    To compare stability and range of motion after hemi-hamate reconstruction versus volar plate arthroplasty in a biomechanical proximal interphalangeal (PIP) joint fracture-dislocation model. Eighteen digits from 6 cadaver hands were tested. We created defects of 40%, 60%, and 80% in the palmar base of each digit's middle phalanx, simulating an acute PIP joint fracture-dislocation. Each defect scenario was reconstructed with a hemi-hamate arthroplasty followed by a volar plate arthroplasty. A computer-controlled mechanism was used to bring each digit's PIP joint from full extension to full flexion via the digital tendons in each testing state, and in the intact state. During each testing scenario we collected PIP joint cinedata in a true lateral projection using mini-fluoroscopy. A digital radiography program was used to measure the amount of middle phalanx dorsal translation (subluxation) in full PIP joint extension. We recorded the angle at which subluxation, if present, occurred during each testing scenario. Average dorsal displacement of the middle phalanx in relation to the proximal phalanx was 0.01 mm for the hemi-hamate reconstructed joints and -0.03 mm for the volar plate arthroplasty, compared with the intact state. Flexion contractures were noted in each of the specimens reconstructed with volar plate arthroplasty. Degree of contracture was directly correlated with defect size, averaging 20° for 40% defects, 35° for 60% defects, and 60° for 80% defects. We observed no flexion contractures in the hemi-hamate reconstructions. Surgeons can use both hemi-hamate and volar plate arthroplasty to restore PIP joint stability following a fracture dislocation with a large middle phalanx palmar base defect. Use of volar plate arthroplasty led to an increasing flexion contracture as the middle phalanx palmar base defect increased. Clinicians can use the information from this study to help with surgical decision-making and patient education. Copyright © 2015

  12. [Dislocation of the ankle without simoustaneously fracture of the bones].

    PubMed

    Qayyum, Faiza; Qayyum, Abbas Ali; Sahlstrüm, Sven Arne

    2014-09-01

    The ankle is a unique modified saddle joint that, together with the subtalar joint, provides range of motion in several physical planes while maintaining stability. The ankle complex functions as a pivoting structure positioned to bear the entire weight of the body which leaves it vulnerable to injuries. Pure dislocation without associated fracture is rare; however, cases of isolated ankle dislocation without fracture have been reported. We report a case of a closed ankle dislocation without an associated fracture in a 17-year-old boy.

  13. Apollonius of Citium (first century BC) and his work on the treatment of joint dislocations.

    PubMed

    Markatos, Konstantinos; Korres, Demetrios; Chytas, Demetrios; Karamanou, Marianna; Sourlas, Ioannis; Androutsos, Georgios; Mavrogenis, Andreas

    2018-05-01

    The purpose of this study was to summarise the life and work of the Cypriot physician Apollonius of Citium (first century BC). His overall work on medicine is presented, and special emphasis is given to his work on the treatment of joint dislocations. The most famous work of Apollonius is Treatise On Joints, which was preserved on the whole in a manuscript of the tenth century AD. In that manuscript, Apollonius is obviously influenced by the Hippocratic Corpus of Medicine. His description, diagnostic methods and reduction techniques are all based on those described by Hippocrates in his work "On Joints". Apollonius' contribution to this subject concerns accurate depiction in images of the reduction techniques he proposes. His simplifications describe the techniques of Hippocrates in a way they can be understood and used by athletes and nonphysicians in the Greek gymnasia. Perhaps his treatise is one of the earliest works of popularised medicine and surgery in the history of human civilisation.

  14. [Case-control study on measurement of coracoclavicular and acromioclavicular ligament injuries during internal fixation operation for the treatment of fresh acromioclavicular joint dislocation of Tossy type III].

    PubMed

    Guan, Ting-Jin; Sun, Peng; Zheng, Liang-Guo; Qi, Xiang-Yang

    2014-01-01

    To study measurement methods of acromioclavicular and coracoclavicular ligament injuries,its therapeutic effects and complications during internal fixation operation for the treatment of fresh acromioclavicular joint dislocations of Tossy type III. From July 2003 to May 2012,127 patients with acromioclavicular joint dislocations of Tossy type III were treated with wire fixation from coracoid process to clavicle or hook-plate fixation. The patients were divided into group A (63 cases) and group B (64 cases) according to whether acromioclavicular ligament and coracoclavicular ligament were repaired or not. In group A (ligaments repaired), there were 39 males and 24 females with an average age of (33.25 +/- 8.46) years old (ranged from 17 to 59 years). And in group B (no ligaments repaired), there were 41 males and 23 females with an average age of (34.10 +/- 7.19) years (ranged from 19 to 57 years). The operation times, intraoperative blood loss, postoperative infections, internal fixation failure, recurrence and other complications, together with therapeutic effects were compared between two groups. The outcome was analyzed according to Karlsson standard. In group A, 54 patients got an excellent result and 9 good according to Karlsson standard;the average operative time was (55.90 +/- 26.56) min; the average intraoperative bleeding amount was (99.80 +/- 50.30) ml; 1 patient had wire broken without re-dislocation at 16 weeks after operation, 3 patients got wound fat liquefaction and recovered after treatment, 1 patient had pain after shoulder joint motion and pain disappeared after implants were taken out. In group B, 52 patients got an excellent result and 12 good according to Karlsson standard; the average operative time was (49.50 +/- 23.14) min; the average intraoperative bleeding amount was (87.30 +/- 46.41) ml; 2 patients got wound fat liquefaction, and 2 patients had pain after shoulder joint motion. All the patients were followed up, and the duration ranged

  15. Operative treatment of acute acromioclavicular dislocations Rockwood III and V-Comparative study between K-wires combined with FiberTape(®) vs. TightRope System(®).

    PubMed

    Vrgoč, G; Japjec, M; Jurina, P; Gulan, G; Janković, S; Šebečić, B; Starešinić, M

    2015-11-01

    Acromioclavicular (AC) joint dislocations usually occur in a young active population as a result of a fall on the shoulder. Rockwood divided these dislocations into six types. Optimal treatment is still a matter of discussion. Many operative techniques have been developed, but the main choice is between open and minimally-invasive arthroscopic procedures. The aim of this study was to compare two different surgical methods on two groups of patients to find out which method is superior in terms of benefit to the patient. The methods were evaluated through objective and subjective scores, with a focus on complications and material costs. A retrospective two-centre study was conducted in patients with acute AC joint dislocation Rockwood types III and V. The two methods conducted were an open procedure using K-wires combined with FiberTape(®) (Arthrex, Naples, USA) (Group 1) and an arthroscopic procedure using the TightRope System(®) (Arthrex, Naples, USA) (Group 2). Groups underwent procedures during a two-year period. Diagnosis was based on the clinical and radiographic examination of both AC joints. Surgical treatment and rehabilitation were performed. Sixteen patients were included in this study: Group 1 comprised 10 patients, all male, average age 41.6 years (range 17-64 years), Rockwood type III (eight patients) and Rockwood type V (two patients); Group 2 had six patients, one female and five male, average age 37.8 years (range 18-58 years), Rockwood type III (two patients) and Rockwood type V (four patients). Time from injury to surgery was shorter and patients needed less time to return to daily activities in Group 1. Duration of the surgical procedure was shorter in Group 2 compared with Group 1. Complications of each method were noted. According to the measured scores and operative outcome between dislocation Rockwood type III and V, no significant difference was found. Implant material used in Group 2 was 4.7 times more expensive than that used in Group 1

  16. [CT measurement and clinical application of double-row suture anchor reconstruction for the treatment of Tossy type III acromioclavicular joint dislocation].

    PubMed

    Zhang, Chuan-Kai; Liu, Chen; Han, Bing; Feng, Hui; Chen, Qi-Zhong; Sunx, Sun Yi-Yan

    2017-04-25

    To study feasibility and reliability of reconstruction of the acromioclavicular ligament with double-row suture anchor for the treatment of acromioclavicular joint dislocation through coracoid coronal CT measurement, and to provide a new operation method for treating acromioclavicular joint dislocation. Total 60 healthy people received CT examination of shoulder joint, including 30 males and 30 females, ranging in age from 18 to 50 years old. The coronal width, thickness and 20 degree camber angle in the medial part of the toot of coronal were measured using CT scan. The results were applied to clinical treatment for 12 patients with acromioclavicular joint dislocation of Tossy III type. The width in the medial part of the root of the coracoid was(17.65±1.82) mm(left side) and (17.67±1.80) mm(right side) in males; (16.55±1.78) mm(left side) and (16.52±1.74) mm (right side) in females. The vertical thickness of the roots of the coracoid: (13.11±2.11) mm(left side) and (13.16±2.09) mm(right side) in males;(12.79±2.21) mm(left side) and (12.76±2.19) mm (right side) in females. The thickness of 20 degrees camber angle of the coracoid roots: (16.32±1.74) mm (left side) and (16.30±1.69) mm(right side) in males; (15.68±1.44) mm(left side) and (15.67±1.43) mm(right side) in females. Total 12 patients were treated with anchor nail with extraversion 20 degrees. The postoperative X-ray films showed bone anchors were located in the coracoid process, no bone splitting. Double-row suture anchor of 5 mm diameter nails can be placed into coracoid with extraversion 20 degrees, which is safety.

  17. Structure of A-C Type Intervariant Interface in Nonmodulated Martensite in a Ni-Mn-Ga Alloy.

    PubMed

    Ouyang, S; Yang, Y Q; Han, M; Xia, Z H; Huang, B; Luo, X; Zhao, G M; Chen, Y X

    2016-07-06

    The structure of A-C type intervariant interface in nonmodulated martensite in the Ni54Mn25Ga21 alloy was studied using high resolution transmission electron microscopy. The A-C interface is between the martensitic variants A and C, each of which has a nanoscale substructure of twin-related lamellae. According to their different thicknesses, the nanoscale lamellae in each variant can be classified into major and minor lamellae. It is the boundaries between these lamellae in different variants that constitute the A-C interface, which is thus composed of major-major, minor-minor, and major-minor lamellar boundaries. The volume fraction of the minor lamellae, λ, plays an important role in the structure of A-C interfaces. For major-major and minor-minor lamellar boundaries, they are symmetrical or asymmetrical tilt boundaries; for major-minor boundary, as λ increases, it changes from a symmetrical tilt boundary to two asymmetrical microfacets. Moreover, both lattice and misfit dislocations were observed in the A-C interfaces. On the basis of experimental observations and dislocation theory, we explain how different morphologies of the A-C interface are formed and describe the formation process of the A-C interfaces from λ ≈ 0 to λ ≈ 0.5 in terms of dislocation-boundary interaction, and we infer that low density of interfacial dislocations would lead to high mobility of the A-C interface.

  18. Dislocations in bilayer graphene.

    PubMed

    Butz, Benjamin; Dolle, Christian; Niekiel, Florian; Weber, Konstantin; Waldmann, Daniel; Weber, Heiko B; Meyer, Bernd; Spiecker, Erdmann

    2014-01-23

    Dislocations represent one of the most fascinating and fundamental concepts in materials science. Most importantly, dislocations are the main carriers of plastic deformation in crystalline materials. Furthermore, they can strongly affect the local electronic and optical properties of semiconductors and ionic crystals. In materials with small dimensions, they experience extensive image forces, which attract them to the surface to release strain energy. However, in layered crystals such as graphite, dislocation movement is mainly restricted to the basal plane. Thus, the dislocations cannot escape, enabling their confinement in crystals as thin as only two monolayers. To explore the nature of dislocations under such extreme boundary conditions, the material of choice is bilayer graphene, the thinnest possible quasi-two-dimensional crystal in which such linear defects can be confined. Homogeneous and robust graphene membranes derived from high-quality epitaxial graphene on silicon carbide provide an ideal platform for their investigation. Here we report the direct observation of basal-plane dislocations in freestanding bilayer graphene using transmission electron microscopy and their detailed investigation by diffraction contrast analysis and atomistic simulations. Our investigation reveals two striking size effects. First, the absence of stacking-fault energy, a unique property of bilayer graphene, leads to a characteristic dislocation pattern that corresponds to an alternating AB B[Symbol: see text]AC change of the stacking order. Second, our experiments in combination with atomistic simulations reveal a pronounced buckling of the bilayer graphene membrane that results directly from accommodation of strain. In fact, the buckling changes the strain state of the bilayer graphene and is of key importance for its electronic properties. Our findings will contribute to the understanding of dislocations and of their role in the structural, mechanical and electronic

  19. A rare combined injury of dorsal fracture-dislocation of four carpometacarpal joints and trapezium, trapezoid and distal radius bone fractures.

    PubMed

    Touloupakis, Georgios; Stuflesser, Wilfried; Antonini, Guido; Ferrara, Fabrizio; Crippa, Cornelio; Lettera, Maria Gabriella

    2016-05-06

    Incorrect or delayed diagnosis and treatment of the carpometacarpal fracture-dislocations is often associated with poor prognosis. We present a rare case of unusual pattern of injury, involving dorsal dislocation of four ulnar carpometacarpal joints, associated with fracture of the trapezium, a burst fracture of the trapezoid  bone and an extra-articular fracture of the third distal  of the radius. The first surgical intervention was followed by unsatisfactory results, confirmed by the CT scans. A second surgery followed and an open reduction and pinning with K wires performed. Post-operative follow up lasting for nine months revealed a very good surgical outcome.

  20. Rotational and translational stability of different methods for direct acromioclavicular ligament repair in anatomic acromioclavicular joint reconstruction.

    PubMed

    Beitzel, Knut; Obopilwe, Elifho; Apostolakos, John; Cote, Mark P; Russell, Ryan P; Charette, Ryan; Singh, Hardeep; Arciero, Robert A; Imhoff, Andreas B; Mazzocca, Augustus D

    2014-09-01

    Many reconstructions of acromioclavicular (AC) joint dislocations have focused on the coracoclavicular (CC) ligaments and neglected the functional contribution of the AC ligaments and the deltotrapezial fascia. To compare the modifications of previously published methods for direct AC reconstruction in addition to a CC reconstruction. The hypothesis was that there would be significant differences within the variations of surgical reconstructions. Controlled laboratory study. A total of 24 cadaveric shoulders were tested with a servohydraulic testing system. Two digitizing cameras evaluated the 3-dimensional movement. All reconstructions were based on a CC reconstruction using 2 clavicle tunnels and a tendon graft. The following techniques were used to reconstruct the AC ligaments: a graft was shuttled underneath the AC joint back from anterior and again sutured to the acromial side of the joint (group 1), a graft was fixed intramedullary in the acromion and distal clavicle (group 2), a graft was passed over the acromion and into an acromial tunnel (group 3), and a FiberTape was fixed in a cruciate configuration (group 4). Anterior, posterior, and superior translation, as well as anterior and posterior rotation, were tested. Group 1 showed significantly less posterior translation compared with the 3 other groups (P < .05) but did not show significant differences compared with the native joint. Groups 3 and 4 demonstrated significantly more posterior translation than the native joint. Group 1 showed significantly less anterior translation compared with groups 2 and 3. Group 3 demonstrated significantly more anterior translation than the native joint. Group 1 demonstrated significantly less superior translation compared with the other groups and with the native joint. The AC joint of group 1 was pulled apart less compared with all other reconstructions. Only group 1 reproduced the native joint for the anterior rotation at the posterior marker. Group 4 showed

  1. [Design and clinical application of the drilling guide in the treatment of acromioclavicular joint dislocation with closed reduction and Kirschner fixation].

    PubMed

    Zhou, Song; Hao, Yong-qiang; Shi, Xiao-lin; Zhao, Huan-li; Gao, Kai-tuo; Sun, Jin-xu

    2011-03-01

    To investigate a drilling guide in the treatment of acromioclavicular joint dislocation with closed reduction and Kirschner fixation and explore the therapeutic effect. From June 2008 to December 2009, 36 patients with acromioclavicular joint dislocation (Tossy III) were treated with closed reduction and Kirschner fixation using a self-designed drilling guide as well as percutaneous repair of acromioclavicular joint. Among the patients, 24 patients were male and 12 patients were female,ranging in age from 20 to 61 years, averaged 38.6 years. The duration from injury to operation ranged from 3.5 to 72 h,with a mean of 15.2 h. No clavicle fracture was found in all cases. The operative time, intra-operative bleeding and therapeutic effects were observed. There were no complications including neurovascular problems. The mean operating time were 20 min,mean blood loss were about 10 ml. According to the observation of postoperative X-ray examination, all Kirschners in acromioclavicular joint were in place. All Kirschners were removed in 6 postoperative weeks. All the patients were followed up ranging from 2 to 26 months (averaged 14.3 months). According to the Karlsson standard,22 patients got an excellent result, 13 good and 1 poor. This method has following advantages: easy operation and fixation; minimum injuries to articular surface; and which would be widely used in clinical practice.

  2. Position of the prosthesis and the incidence of dislocation following total hip replacement.

    PubMed

    He, Rong-xin; Yan, Shi-gui; Wu, Li-dong; Wang, Xiang-hua; Dai, Xue-song

    2007-07-05

    Dislocation is the second most common complication of hip replacement surgery, and impact of the prosthesis is believed to be the fundamental reason. The present study employed Solidworks 2003 and MSC-Nastran software to analyze the three dimensional variables in order to investigate how to prevent dislocation following hip replacement surgery. Computed tomography (CT) imaging was used to collect femoral outline data and Solidworks 2003 software was used to construct the cup model with variabilities. Nastran software was used to evaluate dislocation at different prosthesis positions and different geometrical shapes. Three dimensional movement and results from finite element method were analyzed and the values of dislocation resistance index (DRI), range of motion to impingement (ROM-I), range of motion to dislocation (ROM-D) and peak resisting moment (PRM) were determined. Computer simulation was used to evaluate the range of motion of the hip joint at different prosthesis positions. Finite element analysis showed: (1) Increasing the ratio of head/neck increased the ROM-I values and moderately increased ROM-D and PRM values. Increasing the head size significantly increased PRM and to some extent ROM-I and ROM-D values, which suggested that there would be a greater likelihood of dislocation. (2) Increasing the anteversion angle increased the ROM-I, ROM-D, PRM, energy required for dislocation (ENERGY-D) and DRI values, which would increase the stability of the joint. (3) As the chamber angle was increased, ROM-I, ROM-D, PRM, Energy-D and DRI values were increased, resulting in improved joint stability. Chamber angles exceeding 55 degrees resulted in increases in ROM-I and ROM-D values, but decreases in PRM, Energy-D, and DRI values, which, in turn, increased the likelihood of dislocation. (4) The cup, which was reduced posteriorly, reduced ROM-I values (2.1 -- 5.3 degrees ) and increased the DRI value (0.073). This suggested that the posterior high side had the

  3. Traumatic dislocation of the incudostapedial joint repaired with fibrin tissue adhesive.

    PubMed

    Nikolaidis, Vasilios

    2011-03-01

    We present a case of traumatic dislocation of the incudostapedial joint (ISJ) and a simple method for controlled application of the glue using commercial fibrin tissue adhesive. A 26-year-old female presented to our ENT clinic for hearing impairment to her left ear 2 months after a head trauma due to a motorcycle accident. The audiogram revealed a 40- to 50-dB HL conductive hearing loss with a notch configuration in bone conduction curve on the left ear. Computed tomography of the left temporal bone revealed a longitudinal fracture line. An exploratory tympanotomy was performed under general anesthesia. The ISJ was found dislocated while the incus was trapped by the edges of the bony lateral attic wall fracture. A small bony edge that impeded incus movement was removed and a small amount of the glue was precisely applied to the lenticular process of the incus with an angled incision knife. The long process of the incus was firmly pressed over the stapes for 30 seconds with a 90° hook and 60 seconds after the application of the glue the ISJ was repaired. One year after our patient achieved full airbone gap (ABG) closure (ABG, ≤10 dB HL), while she demonstrated overclosure in frequencies 2 and 4 kHz. Fibrin tissue glue allowed safe, rapid, and accurate repair of the ISJ and resulted in an anatomically normal articulation as the mass and shape of the ossicles was preserved. Moreover, our patient achieved full ABG closure. Copyright © 2011 The American Laryngological, Rhinological, and Otological Society, Inc.

  4. Base of coracoid process fracture with acromioclavicular dislocation in a child

    PubMed Central

    2010-01-01

    Fracture of the coracoid process is a rare injury. It can be easily missed when associated with other injuries to the shoulder girdle, for instance, acromioclavicular joint (ACJ) dislocation. Clinical attention is easily drawn to the more obvious ACJ dislocation, hence, the need for further radiological evaluation. We report an unusual case of fracture of the base of coracoid process associated with a true acromioclavicular joint dislocation in a 12 year old boy, with no separation of the epiphyseal plate, as one might expect. Treatment also remains controversial. Our patient underwent open reduction internal fixation of the acromioclavicular joint and coracoid process. He subsequently made an uneventful progress with pain free full range of shoulder movement at 5 months, and was discharged at 9 months. PMID:20955595

  5. Ligamentous and capsular injuries to the metacarpophalangeal joints of the hand.

    PubMed

    Shah, Smiresh Suresh; Techy, Fernando; Mejia, Alfonso; Gonzalez, Mark H

    2012-01-01

    The mechanism of dorsal dislocation of the metacarpophalangeal (MCP) joint is with forced hyperextension of the joint and the main structure injured is the volar plate. A simple dislocation can be reduced by closed means whereas a complex dislocation cannot. Care must be taken not to put traction across the joint, which may cause the volar plate to slip into the joint, converting a simple dislocation into a complex dislocation. Volar dislocations are rare and mainly treated nonoperatively. Sagittal band injuries can be treated with extension splinting or surgical management with direct repair or reconstruction. A locked MCP joint can usually be treated with closed manipulation. This article discusses these injuries and management options.

  6. Arthroscopically assisted reduction of acute acromioclavicular joint dislocation using a single double-button device: Medium-term clinical and radiological outcomes.

    PubMed

    Issa, S-P; Payan, C; Le Hanneur, M; Loriaut, P; Boyer, P

    2018-02-01

    Double-button devices for endoscopic management of acute acromioclavicular joint dislocation (ACJD) provide satisfactory short-term functional and radiological results. However, little exists in the literature regarding the long- and medium-term results of these implants, especially regarding the evolution of the acromioclavicular joint (ACJ). Satisfactory and steady long- and medium-term outcomes can be achieved in patients with acute ACJD undergoing endoscopically assisted ACJ repair using a single double-button device. A retrospective single-center study was conducted in patients with acute Rockwood III and IV ACJD treated endoscopically with a single double-button device from October 2008 to October 2010, allowing a minimum 5-year follow-up. Functional evaluation used Constant and Quick-DASH scores. Clinical evidence of dislocation recurrence was combined with bilateral Zanca views to assess coracoclavicular distance. Acromioclavicular osteoarthritis was evaluated on the Paxinos test and Zanca views. Nineteen of the 25 operated patients were seen at a mean 76.9±8.5 months' follow-up. Mean age was 34.4±8.3 years. Mean Constant and Quick-DASH scores were 96.2±5.1 and 0.9±1.6 points, respectively. Four patients had a recurrence of their initial dislocation, 3 of whom had positive Paxinos test, whereas the 15 patients without recurrence had a negative test (p=0.004). Five patients had radiological evidence of ACJ osteoarthritis: all 4 patients with recurrence and 1 without (p=0.001). Long- and medium-term radioclinical outcome of endoscopically assisted management of acute ACJD using a single double-button device seems to be satisfactory and steady over time. Recurrence of the initial dislocation appears to be related to onset of degenerative ACJ arthropathy. Therapeutic type IV-Retrospective case series. Copyright © 2017 Elsevier Masson SAS. All rights reserved.

  7. Results of Operative and Nonoperative Treatment of Rockwood Types III and V Acromioclavicular Joint Dislocation

    PubMed Central

    Joukainen, Antti; Kröger, Heikki; Niemitukia, Lea; Mäkelä, E. Antero; Väätäinen, Urho

    2014-01-01

    Background: The optimal treatment of acute, complete dislocation of the acromioclavicular joint (ACJ) is still unresolved. Purpose: To determine the difference between operative and nonoperative treatment in acute Rockwood types III and V ACJ dislocation. Study Design: Randomized controlled trial; Level of evidence, 2. Methods: In the operative treatment group, the ACJ was reduced and fixed with 2 transarticular Kirschner wires and ACJ ligament suturing. The Kirschner wires were extracted after 6 weeks. Nonoperatively treated patients received a reduction splint for 4 weeks. At the 18- to 20-year follow-up, the Constant, University of California at Los Angeles Shoulder Rating Scale (UCLA), Larsen, and Simple Shoulder Test (SST) scores were obtained, and clinical and radiographic examinations of both shoulders were performed. Results: Twenty-five of 35 potential patients were examined at the 18- to 20-year follow-up. There were 11 patients with Rockwood type III and 14 with type V dislocations. Delayed surgical treatment for ACJ was used in 2 patients during follow-up: 1 in the operatively treated group and 1 in the nonoperatively treated group. Clinically, ACJs were statistically significantly less prominent or unstable in the operative group than in the nonoperative group (normal/prominent/unstable: 9/4/3 and 0/6/3, respectively; P = .02) and in the operative type III (P = .03) but not type V dislocation groups. In operatively and nonoperatively treated patients, the mean Constant scores were 83 and 85, UCLA scores 25 and 27, Larsen scores 11 and 11, and SST scores 11 and 12 at follow-up, respectively. There were no statistically significant differences in type III and type V dislocations. In the radiographic analysis, the ACJ was wider in the nonoperative than the operative group (8.3 vs 3.4 mm; P = .004), and in the type V dislocations (nonoperative vs operative: 8.5 vs 2.4 mm; P = .007). There was no statistically significant difference between study groups in

  8. Ulnar Rotation Osteotomy for Congenital Radial Head Dislocation.

    PubMed

    Liu, Ruiyu; Miao, Wusheng; Mu, Mingchao; Wu, Ge; Qu, Jining; Wu, Yongtao

    2015-09-01

    To evaluate an ulnar rotation osteotomy for congenital anterior dislocation of the radial head. Nine patients (5 boys and 4 girls aged 6 to 13 years) with congenital anterior dislocation of the radial head were treated with ulnar rotation osteotomy. Magnetic resonance imaging of the elbow showed the proximal radioulnar joint on the anterior-lateral side of the ulna rather than on the lateral side in patients with congenital anterior dislocation of the radial head. On the basis of this finding, we performed an osteotomy on the ulna and laterally rotated the proximal radioulnar joint achieving radial head reduction and restoring the anatomical relationship between the radial head and the capitellum. Clinical and radiographical evaluation of the elbow was performed before surgery and at postoperative follow-up. All patients were followed for 13 to 45 months after surgery. Elbow radiography showed that the radiocapitellar joint was reduced in all patients at the last follow-up visit and that the carrying angle was decreased relative to that in the preoperative condition. Elbow stability and the range of elbow flexion motion were improved at the last follow-up. We did not observe ulnar osteotomy site nonunion or elbow osteoarthritis in these patients. Furthermore, radial head dislocation did not recur. At early follow-up, ulnar rotation osteotomy was a safe and effective method for the treatment of congenital anterior dislocation of the radial head. Therapeutic IV. Copyright © 2015 American Society for Surgery of the Hand. Published by Elsevier Inc. All rights reserved.

  9. [Injuries of the acromioclavicular joint].

    PubMed

    Meeder, P J; Dannöhl, C

    1988-07-01

    The injuries of the acromio-clavicular joint require a differentiated diagnosis and treatment. The classification of the acromio-clavicular dislocations from grade I to grade III according to Tossy is proved. The diagnosis of a complete acromio-clavicular dislocation (Tossy III) is an indication for a surgical repair. Many and different methods are reported in the literature. 178 patients with a fresh acromio-clavicular dislocation (Typ Tossy II and III) were treated at the BG-Unfallklinik Tübingen from 1970 to 1987 by suturing the ligaments, inserting pins across the joint and tension wire bending. In old cases with Tossy III dislocation of the acromio-clavicular joint an oblique osteotomy combined with the reduction of the clavicle is recommended as a method of choice. The results of these procedures and there possible intra- and postoperative complications are reported. The incision along the clavicle quite often gives scar problems. Therefore the advantages of an arched incision across the acromio-clavicular joint is pointed out. Because of there biomechanical relationship fractures in the lateral third of the clavicle are similar to dislocations of the acromio-clavicular joint. The classification of these fractures according to Jäger, Buschle and Breitner allows a differentiated management of these lesions.

  10. [EFFECTIVENESS COMPARISON OF CORACOCLAVICULAR LIGAMENT RECONSTRUCTION BETWEEN BY AUTOLOGOUS AND ALLOGENEIC TENDON GRAFTS COMBINED WITH HOOK PLATE FIXATION FOR TREATING ACROMIOCLAVICULAR JOINT DISLOCATION].

    PubMed

    Yin, Fei; Sun, Zhenzhong; Wei, Xuming; Liu, Xueguang; Zhou, Ming; Zhuang, Yin; Song, Sheng

    2016-05-08

    To compare the effectiveness of coracoclavicular ligament reconstruction between by using autologous plantaris tendon graft combined with hook plate fixation and allogeneic tendon graft combined with hook plate fixation for treating acromiocavicular joint dislocation. Thirty-three patients with acromioclavicular joint dislocation who accorded with the inclusion criteria between January 2013 and June 2014 were assigned into 2 groups. The patients were treated with autologous plantaris tendon graft combined with hook plate fixation in group A ( n =17), and with allogeneic tendon graft combined with hook plate fixation in group B ( n =16). Thirteen-one patients was followed up more than 12 months (15 in group A and 16 in group B). There was no significant difference in gender, age, cause of injury, sides, time between injury and surgery, and type of dislocation ( P >0.05). The assessments included operation time, hospitalization time, hospitalization expenses, shoulder range of motion, gap of acromioclavicular, Constant-Murley scores, and visual analogue scale (VAS) for pain. The operation time of group A was significantly longer than that of group B, and the hospitalization expense was significantly lower than that of group B ( P <0.05). There was no significant difference in hospitalization time ( t =1.046, P =0.316). The incisions healed by first intention, and hook plate was removed after 3 months. The mean follow-up time was 21.3 months (range, 19-34 months) in group A and was 23.7 months (range, 18-37 months) in group B. X-ray examination showed no osteolysis. There was no significant difference in gap of acromiocavicular between 2 groups at preoperation, 1 week after operation, and last follow-up ( P >0.05). No redislocation of acromioclavicular joint and rejection reaction occurred during follow-up. At last follow-up, there was no significant difference in shoulder range of motion, Constant-Murley score, and VAS score between 2 groups ( P >0

  11. Diagnosis of Ehlers-Danlos syndrome after a first shoulder dislocation.

    PubMed

    Nourissat, Geoffroy; Vigan, Marie; Hamonet, Claude; Doursounian, Levon; Deranlot, Julien

    2018-01-01

    Shoulder dislocation is often the first symptom of Ehlers-Danlos syndrome (EDS). Whether it occurs in early-onset EDS is unknown. In most cases, surgical failure leads to the diagnosis. We aimed to determine whether clinical symptoms can signal the presence of EDS at a first dislocation. In this retrospective study, we analyzed clinical and radiologic data for 27 patients with EDS and shoulder instability and a control population of 40 consecutive non-EDS patients undergoing surgery for an unstable shoulder. Data were collected on gender, age, single or bilateral disease, general hyperlaxity, shoulder hyperlaxity, number of dislocations or subluxations, nontraumatic onset, and pain specificity. Nerve and vascular injuries, joint disorders, and family history were recorded, and radiologic data were reported. Age <14 years, female sex, bilateral disorder, and general hyperlaxity were significantly more frequent in patients with EDS and a first dislocation than in those without EDS. Painless dislocation with pain after dislocation and concomitant nerve injury were more frequent in affected patients, as were hemostasis disorders and a family history of joint hyperlaxity. Bone lesions were not seen on radiographs. Only the hyperlaxity sign (external rotation >85°) did not differ between the groups. After a first dislocation in a young girl with global hyperlaxity but not necessarily shoulder hyperlaxity, painless atraumatic dislocation with pain after reduction can suggest EDS. Copyright © 2018. Published by Elsevier Inc.

  12. Open dislocation of the proximal interphalangeal joint of the little finger subsequent to chronic radial collateral ligament injury: a case report of primary ligament reconstruction with a half-slip of the flexor digitorum superficialis: Case Report.

    PubMed

    Wada, Kazuma; Hibino, Naohito; Kondo, Kenji; Yoshioka, Shinji; Terai, Tomoya; Henmi, Tatsuhiko; Sairyo, Koichi

    2015-01-01

    Open dislocation of the proximal interphalangeal (PIP) joint is relatively rare. We report a case of a 32-year-old man who had open dislocation of the PIP joint of the little finger while playing American football. He had a history of chronic radial collateral ligament injury. We reconstructed the radial collateral ligament with a half-slip of the flexor digitorum superficialis tendon.

  13. Ipsilateral hip and knee dislocation: Case report and review of literature

    PubMed Central

    Sharma, Gaurav; Chahar, Deepak; Sreenivasan, Ravi; Verma, Nikhil; Pankaj, Amite

    2016-01-01

    Hip and knee dislocations are not uncommon but simultaneous ipsilateral dislocation of the hip and knee joint is rare; consequently, there is an inadequate amount of literature on the subject. We identified only 11 such cases reported in English literature. In the present report, we describe the case of a 23-year-old male patient who presented with ipsilateral hip and knee dislocation on the right side after being involved in a road traffic accident. The hip dislocation was associated with a posterior wall acetabular fracture. The hip as well as the knee joints was reduced in the emergency bay. The patient underwent an urgent fixation of the posterior wall acetabular fracture with delayed ligament reconstruction for the knee dislocation. At one-year follow-up, he had no pain in the hip or knee. There was grade 1 posterior sag but no symptoms of knee instability. Radiographs revealed no evidence of avascular necrosis or arthritis of the femoral head. The normal treatment protocol for individual injury is affected by the simultaneous occurrence of hip and knee dislocation. PMID:27182149

  14. [Analysis on the long-term effects of modified double endobutton technique in the treatment of Tossy type III acromioclavicular joint dislocations].

    PubMed

    Yan, Rui-Jian; Lu, Jian-Wei; Zhang, Chun

    2014-01-01

    To investigate the long-term clinical effects of modified double Endobutton technique for the treatment of acromioclavicular joint dislocations of Tossy type III. A retrospective study was done in 42 patients with acromioclavicular joint dislocations of Tossy type III treated with modified double Endobutton technique from December 2008 to December 2010. There were 24 males and 18 females, ranging in age from 21 to 56 years old (averaged, 32.5 years old). All the patients were treated with open reduction, coracoclavicular ligament reconstruction using double Endobutton technique, and repair of acromioclavicular ligament. The Karlsson system was used to evaluate therapeutic effects. The distance from coracoid to clavicle was measured to evaluate reduction loss. All the patients were followed up, and the duration ranged from 2.0 to 3.2 years (averaged,2.4 years). According to Karlsson system, 32 patients got an A degree and 10 patients got a B degree at three months post-operatively; 26 patients got an A degree and 16 patients got a B degree at the latest follow-up; 6 patients got an A degree at 3 months after operation lowered to B degree at the latest follow-up. The coracoid-clavicle distance increased from (26.91 +/- 0.91) mm at 3 months after operation to (27.41 +/- 1.10) mm at the latest follow-up. Te patients treated with over-reduction during operation or with heavy physical labour work after operation had obvious widened coracoid-clavicle distance. Bone absorption was found around the plate in most cases, mainly in the clavicular side. Treatment for acromioclavicular joint dislocations of Tossy type III with modified double Endobutton technique has satisfactory early clinical results. But with time passing, loss of reduction and bone absorption around the plate could be observed, and clinical outcomes of some cases downgrade during the long-term follow-up.

  15. Biomechanical study of four kinds of percutaneous screw fixation in two types of unilateral sacroiliac joint dislocation: a finite element analysis.

    PubMed

    Zhang, Lihai; Peng, Ye; Du, Chengfei; Tang, Peifu

    2014-12-01

    To compare the biomechanical stability of four different kinds of percutaneous screw fixation in two types of unilateral sacroiliac joint dislocation. Finite element models of unstable Tile type B and type C pelvic ring injuries were created in this study. Modelling was based on fixation with a single S1 screw (S1-1), single S2 screw (S2-1), two S1 screws (S1-2) and a combination of a single S1 and a single S2 screw (S1–S2). The biomechanical test of two types of pelvic instability (rotational or vertical) with four types of percutaneous fixation were compared. Displacement, flexion and lateral bend (in bilateral stance) were recorded and analyzed. Maximal inferior translation (displacement) was found in the S2-1 group in type B and C dislocations which were 1.58 mm and 1.90 mm, respectively. Maximal flexion was found in the S2-1 group in type B and C dislocations which were 1.55° and 1.95°, respectively. The results show that the flexion from most significant angulation to least is S2-1, S1-1, S1-2, and S1–S2 in type B and C dislocations. All the fixations have minimal lateral bend. Our findings suggest single screw S1 fixation should be adequate fixation for a type B dislocation. For type C dislocations, one might consider a two screw construct (S1–S2) to give added biomechanical stability if clinically indicated.

  16. Point-of-care ultrasound facilitates diagnosing a posterior shoulder dislocation.

    PubMed

    Mackenzie, David C; Liebmann, Otto

    2013-05-01

    Posterior shoulder dislocation is an uncommon disruption of the glenohumeral joint. Risk factors include seizure, electric shock, and underlying instabilities of the shoulder joint. A 27-year-old man with a history of recurrent posterior shoulder dislocation presented to the Emergency Department with sudden shoulder pain and reduced range of motion about the shoulder after abducting and internally rotating his arm. Radiographs did not show fracture or dislocation. The treating physician suspected an occult posterior shoulder dislocation, but wanted to avoid performing a computed tomography scan of the shoulder, as the patient had undergone numerous scans during the evaluation of similar complaints. Instead, a point-of-care ultrasound was performed, demonstrating posterior displacement of the humeral head relative to the glenoid rim, confirming the presence of a posterior shoulder dislocation. The patient received procedural sedation, and the shoulder was reduced with real-time ultrasound visualization. The patient tolerated the procedure well, and had decreased pain and improved range of motion. He was discharged with a sling, swathe, and orthopedic follow-up. Point-of-care ultrasound of the shoulder may be used to demonstrate posterior shoulder dislocation. This may have particular utility in the setting of non-diagnostic radiographs. Copyright © 2013. Published by Elsevier Inc.

  17. [Relevance of MRI After Closed Reduction of Traumatic Hip Dislocation in Children].

    PubMed

    Strüwind, Christoph Mauritz; von Rüden, Christian; Thannheimer, Andreas; Bühren, Volker; Schneidmueller, Dorien

    2018-05-14

    Traumatic hip dislocation in children and adolescents is a rare entity that typically results from high-energy trauma. After closed joint reduction, further treatment depends on the specific pattern of the lesion as identified using cross sectional imaging. The aim of this retrospective analysis was to evaluate relevant side effects after traumatic hip dislocation in children and adolescents in order to examine the need for focused diagnostics. This retrospective analysis covered 8 adolescents under 18 years suffering isolated traumatic hip joint dislocation between 2001 and 2017. In all patients, closed joint reduction was performed immediately after admission to the emergency room. In order to evaluate the complete extent of the injury, 5 patients received an MRI and 3 patients a CT scan following closed joint reduction. Two female and 6 male patients with a median age of 11 (range 5 - 16) years were included. In 2 cases, a free joint body was detected in the posterior joint gap in the posttraumatic CT scan after closed joint reduction. Interposition of the labrum into the joint gap was detected intraoperatively in both cases. In one patient who received posttraumatic MRI, labral interposition into the joint gap was observed after closed reduction. These findings were confirmed intraoperatively. In 4 other patients, no posttraumatic labral lesion was detected in the MRI after closed reduction. The reported side effects included ruptured anterior inferior iliac spine and ruptured femoral head ligament. MRI is gaining increasing importance following traumatic hip dislocation in children and adolescents. A missing chondral or osteochondral fragment in the CT scan does not exclude a labral lesion or interposition. Therefore, MRI following closed reduction is mandatory in any case. Georg Thieme Verlag KG Stuttgart · New York.

  18. [New varieties of lateral metatarsophalangeal dislocations of the great toe].

    PubMed

    Bousselmame, N; Rachid, K; Lazrak, K; Galuia, F; Taobane, H; Moulay, I

    2001-04-01

    We report seven cases of traumatic dislocation of the great toe, detailing the anatomy, the mechanism of injury and the radiographic diagnosis. We propose an additional classification based on three hereto unreported cases. Between october 1994 and october 1997, we treated seven patients with traumatic dislocation of the first metatarso-phalangeal joint of the great toe. There were six men and one woman, mean age 35 years (range 24 - 44 years). Dislocation was caused by motor vehicle accidents in four cases and by falls in three. Diagnosis was made on anteroposterior, lateral and medial oblique radiographs. According to Jahss' classification, there was one type I and three type IIB dislocations. There was also one open lateral dislocation and two dorsomedial dislocations. Only these dorsomedial dislocations required open reduction, done via a dorsal approach. Mean follow-up was 17.5 months (range 9 - 24 months) in six cases. One patient was lost to follow-up. The outcome was good in six cases and poor in one (dorsomedial dislocation). Dislocation of the first metatarso-phalangeal joint of the great toe is an uncommon injury. In 1980, Jahss reported two cases and reviewed three others described in the literature. He proposed three types of dislocation based on the feasibility of closed reduction (type I, II and IIB). In 1991, Copeland and Kanat reported a unique case in which there was an association of IIA and IIB lesions. They proposed an addition to the classification (type IIC). In 1994, Garcia Mata et al. reported another case which had not been described by Jahss and proposed another addition. All dislocations reported to date have been sagittal dislocations. Pathological alteration of the collateral ligaments has not been previously reported. In our experience, we have seen one case of open lateral dislocation due, at surgical exploration, to medial ligament rupture and two cases of dorsomedial dislocation due, at surgical exploration, to lateral ligament

  19. Clinical factors that affect perceived quality of life in arthroscopic reconstruction for acromioclavicular joint dislocation.

    PubMed

    Abat, F; Gich, I; Natera, L; Besalduch, M; Sarasquete, J

    To analyse the results of arthroscopic repair of acromioclavicular dislocation in terms of health-related quality of life. Prospective study of patients with acromioclavicular dislocation Rockwood grade iii-v, treated arthroscopically with a mean follow up of 25.4 months. The demographics of the series were recorded and evaluations were performed preoperatively, at 3 months and 2 years with validated questionnaires as Short Form-36 Health Survey (SF-36), visual analogue scale (VAS), The Disabilities of the Arm, Shoulder and Hand (DASH), Constant-Murley Shoulder Outcome Score (Constant) and Walch-Duplay Score (WD). Twenty patients, 17 men and 3 women with a mean age of 36.1 years, were analysed. According to the classification of Rockwood, 3 patients were grade iii, 3 grade iv and 14 grade v. Functional and clinical improvement was detected in all clinical tests (SF-36, VAS and DASH) at 3 months and 2 years follow up (P<.001). The final Constant score was 95.3±2.4 and the WD was 1.8±0.62. It was not found that the health-related quality of life was affected by any variable studied except the evolution of DASH. The health-related quality of life (assessed by SF-36) in patients undergoing arthroscopic repair of acromioclavicular joint dislocation grades iii-v was not influenced by gender, age, grade, displacement, handedness, evolution of the VAS, scoring of the Constant or by the WD. However, it is correlated with the evolution in the DASH score. Copyright © 2017 SECOT. Publicado por Elsevier España, S.L.U. All rights reserved.

  20. Accuracy of acromioclavicular joint injections.

    PubMed

    Wasserman, Bradley R; Pettrone, Sarah; Jazrawi, Laith M; Zuckerman, Joseph D; Rokito, Andrew S

    2013-01-01

    Injection to the acromioclavicular (AC) joint can be both diagnostic and therapeutic. The purpose of this study was to evaluate the accuracy of in vivo AC joint injections. Case series; Level of evidence, 4. Thirty patients with pain localized to the AC joint were injected with 1 mL of 1% lidocaine and 0.5 mL of radiographic contrast material (Isovue). Radiographs of the AC joint were taken after the injection. Each radiograph was reviewed by a musculoskeletal radiologist and graded as intra-articular, extra-articular, or partially intra-articular. Of the 30 injections performed, 13 (43.3%) were intra-articular, 7 (23.3%) were partially articular, and 10 (33.3%) were extra-articular. When the intra-articular and the partially articular groups were combined, 20 patients (66.7%) had some contrast dye in the AC joint. This study demonstrates that despite the relatively superficial location of the AC joint, the clinical accuracy of AC joint injections remains relatively low.

  1. Gradual Reduction of Chronic Fracture Dislocation of the Ankle Using Ilizarov/Taylor Spatial Frame

    PubMed Central

    Deland, Jonathan T.; Rozbruch, S. Robert

    2010-01-01

    With the advances in trauma care, chronic fracture dislocation of the ankle is not a condition commonly seen in modern clinical practice. When encountered, it can be difficult to preserve the ankle joint. We present a case of a 65-year-old female, with a chronic fracture dislocation of the ankle. The ankle joint was subluxated with posterior translation of the talus, displacement of the posterior malleolus fragment, and a distal fibula fracture. A minimally traumatic approach was devised to treat this complex fracture dislocation which included gradual reduction of the ankle with a Taylor spatial frame, followed by stabilization with internal fixation and removal of the frame. Bony union and restoration of the ankle joint congruency was achieved. PMID:22294963

  2. Surgical treatment of chronic mandibular dislocation--report of a case.

    PubMed

    Bakardjiev, Angel G; Atanasov, Dimitar T

    2002-01-01

    Chronic dislocation of the temporomandibular jaw (TMJ) can result from lax joint ligaments and parafunctioning joints; it can also be a consequence of a systemic connective tissue disorder. The authors report a case of hypermobile joint syndrome in combination with mitral valve prolapse. The case was managed by osteosynthesis using modified titanium plate.

  3. Dislocation of the proximal tibiofibular joint, do not miss it

    PubMed Central

    van Wulfften Palthe, Alexander FY; Musters, Linda; Sonnega, Remko JA; van der Sluijs, Hans A

    2015-01-01

    We present a case of a 45-year-old woman with a right proximal tibiofibular dislocation she sustained after a fall during roller skating. Anteroposterior and lateral radiographs confirmed the diagnosis; there were no other injuries. The dislocation was reduced by direct manipulation after intra-articular infiltration, in our emergency department. The patient was treated with a long, non-weight bearing leg cast for 1 week. After 4 weeks, she had no pain and a full range of motion of the knee. PMID:26628303

  4. Quantification of dynamic posterior translation in modified bilateral Alexander views and correlation with clinical and radiological parameters in patients with acute acromioclavicular joint instability.

    PubMed

    Minkus, Marvin; Hann, Carmen; Scheibel, Markus; Kraus, Natascha

    2017-06-01

    Classification of AC-joint instability is based on radiologic evaluation of anteroposterior (a.p.) stress views of both shoulders, neglecting the horizontal component of instability. Recent studies have proposed an association of dynamic posterior translation (DPT) and inferior clinical results. The purpose of this study was to quantify DPT in modified Alexander views and correlate it with other radiological and clinical data. Thirty-two patients (4 f, 28 m, mean age 34.1) with acute AC-joint dislocation (16 = RW III, 16 = RW V) underwent radiological examination including bilateral a.p. stress views with measurement of the coracoclavicular distance (CCD) and bilateral modified Alexander views with different approaches to quantify DPT (overlapping area OA AC , overlapping length OL AC ). In addition, the Constant Score, Subjective Shoulder Value, Taft Score (TF), and the Acromioclavicular Joint Instability Score (ACJI) were obtained. In Rockwood (RW) type III injuries, a mean CCD of 15.8 (9.8-22.8) mm, OA AC of 50.9 (0-216.6) mm 2 , and OL AC of 6.5 (-4.7-17.9) mm were found. RW V patients showed a CCD of 23.1 (13.7-32.0) mm; OA AC 7.0 (0-92.3) mm 2 ; and OL AC -4.8 (-19.6-9.8) mm. Particularly in RW III the CCD, OA AC and OL AC revealed significant correlation with the ACJI (r = -0.64/r = 0.72/r = 0.68, p < 0.05) and TF (r = -0.56/r = 0.68/r = 0.51, p < 0.05). The proposed quantification tools for DPT were found to have a moderate-to-strong correlation with the score results, especially with AC-joint specific scores. RW type V injuries had a moderate correlation with clinical parameters (OA AC with ACJI: r = 0.44, p > 0.05 and OL AC with TF: r = -0.45, p > 0.05). Measuring the OL AC is a convenient way for quantifying DPT in modified Alexander views. It showed significant correlation with clinical scores, indicating the relevance of DPT in patients with AC-joint injury.

  5. Imageological measurement of the sternoclavicular joint and its clinical application.

    PubMed

    Li, Ming; Wang, Bo; Zhang, Qi; Chen, Wei; Li, Zhi-Yong; Qin, Shi-Ji; Zhang, Ying-Ze

    2012-01-01

    Dislocation of the sternoclavicular joint is rare. However, posterior dislocation compressing important structures in the mediastinum may be fatal. Early diagnosis and prompt therapy of sternoclavicular joint dislocation are important. Computed tomography (CT) is an optimal means to investigate sternoclavicular joint anatomy; however, there are few reports on the imageological anatomical features of the sternoclavicular joint. The study investigated imageological anatomical features, and a new plate was devised according to these data to treat sternoclavicular joint dislocation. Fifty-three healthy Chinese volunteers examined with chest CT were included in the study. The coronal, sagittal, and axial images of the sternoclavicular region were reconstructed. The sternal head diameter in the inferolateral-to-superomedial direction, length of the clavicular notch, and angle between the clavicular notch and sternum were measured on coronal images. The angle between the presternum and trunk was measured on sagittal images. The following dimensions were measured on axial images: anteroposterior dimensions of the sternal head, clavicular notch, and presternum; width of the sternoclavicular joint; distance between bilateral clavicles; and minimal distance from the presternum to the underlying structures in the thoracic cavity. A new plate was designed according to the above data and was used to repair six sternoclavicular joint dislocations. All cases were followed up with a range of 9 to 12 months. The proximal clavicle is higher than the presternum in a horizontal position. On axial images, the anteroposterior dimension of the sternal head was longer than the presternum, and the center region of the presternum was thinner than the edges. The left sternoclavicular joint space was (0.82 ± 0.21) cm, and the right was (0.87 ± 0.22) cm. Among the structures behind the sternum, the left bilateral innominate vein ran nearest to the presternum. The distance from the anterior

  6. Axillary artery injury secondary to inferior shoulder dislocation.

    PubMed

    Plaga, Brad R; Looby, Peter; Feldhaus, Steven J; Kreutzmann, Karl; Babb, Aaron

    2010-11-01

    Dislocation injuries of the glenohumeral joint are common in the general public and generally are corrected without complication. One serious complication with shoulder dislocations, or the subsequent reduction, is a lesion to the axillary artery. This specific complication is most frequently seen in the elderly population, where vascular structures have become less flexible. Also, these injuries are most common in association with anterior dislocations of the shoulder. To bring awareness to the possibility of axillary artery injury with inferior dislocation of the shoulder, the treatment options, and a review. We report a 15-year-old male athlete who inferiorly dislocated his shoulder during wrestling practice. The injury was reduced at the scene with manual traction and the patient was transferred to our clinic for evaluation. The patient was determined to have a pseudoaneurysm of the axillary artery, and the history and treatment of the illness are presented. Axillary artery injuries secondary to shoulder dislocations are rare, especially in the young athlete, and proper recognition and treatment offer patients a full recovery. Copyright © 2010. Published by Elsevier Inc.

  7. Septic shoulder presenting as a shoulder dislocation in the pediatric patient: a case report.

    PubMed

    Maguire, Kathleen J; Otsuka, Norman Y

    2017-05-01

    Shoulder dislocation is relatively uncommon in the younger pediatric population. Because of the relative strength of the surrounding soft tissue structures of the shoulder compared with the proximal humeral physis, subluxation or dislocation resulting from a traumatic event or application of force is rare and instead a proximal humeral physeal injury occurs. Case presentation - We present a 5-year-old male who presented to the office with post-traumatic left shoulder pain for about 1 week. Radiographs of the left shoulder indicated inferior subluxation of the humeral head. He was ultimately diagnosed and treated for a septic shoulder. Septic arthritis of the glenohumeral joint accounts for about 3% of all septic arthritis cases. About half of the pediatric patients with a septic arthritis will present with a concomitant osteomyelitis about the joint involved. Widening of the glenohumeral joint and subluxation clinically as well as radiographically have been described in cases of large joint effusions because of an increase in intra-articular fluid in adults. This inferior subluxation is often noted without a frank dislocation. The case described in this report is unique in that this is the first to describe a pediatric septic shoulder presenting as a shoulder subluxation. Given the rarity of pediatric shoulder dislocations and subluxations, the pediatric orthopaedist and pediatrician should maintain a suspicion for a septic joint. Level V.

  8. A Case of Posterior Sternoclavicular Dislocation in a Professional American Football Player

    PubMed Central

    Yang, Justin S.; Bogunovic, Ljiljana; Brophy, Robert H.; Wright, Rick W.; Scott, Reggie; Matava, Matthew

    2015-01-01

    Sternoclavicular (SC) dislocation is a rare injury of the upper extremity. Treatment of posterior SC dislocation ranges from conservative (closed reduction) to operative (open reduction with or without surgical reconstruction of the SC joint). To date, we are unaware of any literature that exists pertaining to this injury or its treatment in elite athletes. The purpose of this case report is to describe a posterior SC joint dislocation in a professional American football player and to illustrate the issues associated with its diagnosis and treatment and the athlete’s return to sports. To our knowledge, this case is the first reported in a professional athlete. He was treated successfully with closed reduction and returned to play within 5 weeks of injury. PMID:26137177

  9. Complications after arthroscopic coracoclavicular reconstruction using a single adjustable-loop-length suspensory fixation device in acute acromioclavicular joint dislocation.

    PubMed

    Shin, Sang-Jin; Kim, Nam-Ki

    2015-05-01

    The purpose of this study was to evaluate clinical and radiological outcomes after arthroscopically assisted coracoclavicular (CC) fixation using a single adjustable-loop-length suspensory fixation device for acute acromioclavicular dislocation and to report intraoperative and postoperative complications. Eighteen consecutive patients with acute acromioclavicular dislocation underwent arthroscopically assisted CC fixation using a single TightRope (Arthrex, Naples, FL). Using the Rockwood classification, 3 patients had grade III dislocations, one patient had a grade IV dislocation, and 14 patients had grade V dislocations. The preoperative CC distance of the injured shoulder was 16.1 ± 2.7 mm (range, 11.2 to 21.0 mm), and it increased by 99% ± 36% (range, 17% to 153%) on average compared with the contralateral shoulder. The average CC distance was 10.5 ± 2.5 mm (range, 7.7 to 15.5 mm), and it increased by 30% ± 30% (range, -9.4% to 90%) at the final follow-up. Compared with immediate postoperative radiographs, the CC distance was maintained in 12 patients, increased between 50% and 100% in 4 patients, and increased more than 100% in 2 patients at final follow-up. However, there was no statistical difference in Constant scores between 6 patients with reduction loss (95.6 ± 4.5) and 12 patients with reduction maintenance (98.4 ± 2.5; P = .17). Perioperative complications occurred in 8 patients, including one case of acromioclavicular arthritis, one case of delayed distal clavicular fracture at the clavicular hole of the device, 3 cases of clavicular or coracoid button failures, and 3 cases of clavicular bony erosion. Satisfactory clinical outcomes were obtained after CC fixation using the single adjustable-loop-length suspensory fixation device for acute acromioclavicular joint dislocation. However, CC fixation failure of greater than 50% of the unaffected side in radiological examinations occurred in 33% of the patients within 3 months after the operation

  10. Management of acute anterior shoulder dislocation.

    PubMed

    Dala-Ali, Benan; Penna, Marta; McConnell, Jamie; Vanhegan, Ivor; Cobiella, Carlos

    2014-08-01

    Shoulder dislocation is the most common large joint dislocation in the body. Recent advances in radiological imaging and shoulder surgery have shown the potential dangers of traditional reduction techniques such as the Kocher's and the Hippocratic methods, which are still advocated by many textbooks. Many non-specialists continue to use these techniques, unaware of their potential risks. This article reviews the clinical and radiographic presentation of dislocation; some common reduction techniques; their risks and success rate; analgesia methods to facilitate the reduction; and postreduction management. Many textbooks advocate methods that have been superceded by safer alternatives. Trainees should learn better and safer relocation methods backed up by the current evidence available. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions.

  11. [Palmar lunate dislocation].

    PubMed

    Isenberg, J; Prokop, A; Schellhammer, F; Helling, H J

    2002-12-01

    Palmar lunate dislocation as the end stage of a perilunate dislocation is a very uncommon injury. Having treated 19,534 hospitalized patients between 1 January 1986 and 1 October 2001 the diagnosis was recorded in four male trauma patients (33, 36, 37 and 62 years old). Among the operatively treated carpal dislocations and carpal fracture dislocations those of the lunate were seen in five per cent. The dislocation was caused in by an acute hyperextension injury resulting of falls from heights in three cases, and of a motorcycle accident in a further case. In two of these cases a complete palmar lunate dislocation was analysed that were produced by fall from seven meters heights of a young craftsman and by accident of a motorcyclist. First using a longitudinal palmar approach in both cases a revision of the hemorrhagic carpal canal was performed urgently, the largely denuded lunate was reduced and the repair of identified ligamentous structures was performed by means of sutures respectively suture anchors. Reduction was stabilized with Kirschner wires. Afterwards performed computed tomography identified the result of reduction and associated defects (subluxation distal radioulnar joint). In one patient a soft tissue infection prevented the dorsal ligamentous repair. In spite of a consequent after-treatment and a good functional result a scapho-lunate dissociation was proved. An avascular defect of the lunate could be excluded by magnetic resonance imaging. In case of a secondary performed dorsal repair a persisting carpal stabilization with a satisfactory functional result could achieved. At second hand an advanced carpal collapse was proved. If reduction cannot be achieved by closed manipulation or a loss of reduction is shown, open reduction is indicated first by a palmar approach. An additional dorsal ligamentous repair seems to be necessary. Transfixation by Kirschner wires and suture anchors stabilize the restored anatomic relationships. Wrist immobilization in

  12. Craniovertebral realignment for basilar invagination and atlantoaxial dislocation secondary to rheumatoid arthritis.

    PubMed

    Goel, Atul; Sharma, Praveen

    2004-09-01

    We present our experience of treating nine consecutive cases of rheumatoid arthritis involving the craniovertebral junction by atlantoaxial joint manipulation and attempts towards restoration of craniovertebral region alignments. Between November 2001 and March 2004, nine cases of rheumatoid arthritis involving the craniovertebral junction were treated in our department of neurosurgery. Six patients had basilar invagination and 'fixed' atlantoaxial dislocation and three patients had a retroodontoid process pannus and mobile and incompletely reducible atlantoaxial dislocation. The patients ranged from 24 to 74 years in age. Six patients were males and three were females. Neck pain and spastic quadriparesis were the most prominent symptoms. Surgery involved attempts to reduce the atlantoaxial dislocation and basilar invagination by manual distraction of the facets of the atlas and axis. Reduction of the atlantoaxial dislocation and of basilar invagination and stabilization of the region was achieved by placement of bone graft and metal spacers within the joint and direct inter-articular plate and screw method of atlantoaxial fixation. Following surgery all the patients showed symptomatic improvement and restoration of craniovertebral alignments. Follow-up ranged from four to 48 months (average 28 months). Manipulation of the atlantoaxial joints and restoring the anatomical craniovertebral alignments in selected cases of rheumatoid arthritis involving the craniovertebral junction leads to remarkable and sustained clinical recovery.

  13. [Case-control study on shoulder pain caused by hook palte for the treatment of acromioclavicular joint dislocation].

    PubMed

    Yang, Ying-guo; Cai, Xiao-bing; Wang, Xiao-min; Zhu, Yong-gan; Pan, He-yong

    2015-06-01

    To explore causes of shoulder pain and propose prevention measures in treating acromioclavicular joint dislocation. From January 2005 to January 2013, 86 patients with acromioclavicular joint dislocation (Tossy III) were treated with hook plate fixation, and were divided into two groups. Bsaed on recovery of shoulder function mostly, the patients who suffered from rest pain, motion pain were named as shoulder pain group, while the patients without pain were named as painless group. In shoulder pain group, there were 21 cases including 15 males and and 6 females ranging the age from 22 to 62 years old with an average of (40.6±11.2) years old. There were 8 cases were on the left side and 13 cases were on the right side. In painless group, there were 65 cases including 36 males and and 29 females ranging the age from 19 to 65 years old with an average of (40.0±11.3) years old. There were 33 cases were on the left side and 32 cases were on the right side. The time from injury to operation ranged from 3 h to 8 d with an average of 34.6 h. Shoulder function of all patients were normal before injuried. Postoperative pain, activity of daily living (ADL), range of motion, deltoid muscle strength were compared. Anteflexion,rear protraction, abduction and upthrow of shoulder joint were also compared. Postoperative complications between two groups were observed and compared. All patients were followed up from 12 to 48 months with an average of 18.5 months. Constant-Murley score were used to evaluate clinical efficacy at the least following up, and 13 cases got an excellent results, 5 moderate, 2 good and 1 poor in shoulder pain group ; while 61 cases were obtained excellent results, 3 moderate and 1 good in painless group. There were significantly differences between two groups in Constant-Murley score and activity of shoulder joint (P<0.05). In shoulder pain group, 3 cases were disconnected, 1 case occurred stress fracture, 9 cases were subacromial impingement syndrome, 5

  14. ARTHROSCOPIC TREATMENT OF ACROMIOCLAVICULAR JOINT DISLOCATION BY TIGHT ROPE TECHNIQUE (ARTHREX®)

    PubMed Central

    GÓmez Vieira, Luis Alfredo; Visco, Adalberto; Daneu Fernandes, Luis Filipe; GÓmez Cordero, Nicolas Gerardo

    2015-01-01

    Presenting the arthroscopic treatment by Tight Rope - Arthrex® system for acute acromioclavicular dislocation and to evaluate results obtained with this procedure. Methods: Between August 2006 and May 2007, 10 shoulders of 10 patients with acute acromioclavicular dislocation were submitted to arthroscopic repair using the Tight Rope - Arthrex® system. Minimum follow-up was 12 months, with a mean of 15 months. Age ranged from 26 to 42, mean 34 years. All patients were male. Radiology evaluation was made by trauma series x-ray. The patients were assisted in the first month weekly and after three months after the procedure. Clinical evaluation was based on the University of California at Los Angeles (UCLA) criteria. Results: All patients were satisfied after the arthroscopic procedure and the mean UCLA score was 32,5. Conclusion: The arthroscopic treatment by Tight Rope – Arthrex® system for acute acromioclavicular dislocation showed to be an efficient technique. PMID:26998453

  15. A novel cadaveric model for anterior-inferior shoulder dislocation using forcible apprehension positioning.

    PubMed

    McMahon, Patrick J; Chow, Stephen; Sciaroni, Laura; Yang, Bruce Y; Lee, Thay Q

    2003-01-01

    A novel cadaveric model for anterior-inferior shoulder dislocation using forcible apprehension positioning is presented. This model simulates an in vivo mechanism and yields capsulolabral lesions. The scapulae of 14 cadaveric entire upper limbs (82 +/- 9 years, mean +/- standard deviation) were each rigidly fixed to a custom shoulder-testing device. A pneumatic system was used with pulleys and cables to simulate the rotator cuff and the deltoid muscles (anterior and middle portions). The glenohumeral joint was then positioned in the apprehension position of abduction, external rotation, and horizontal abduction. A 6-degree-of-freedom load cell (Assurance Technologies, Garner, North Carolina) measured the joint reaction force that was then resolved into three orthogonal components of compression force, anteriorly directed force, and superiorly directed force. With the use of a thrust bearing, the humerus was moved along a rail with a servomotor-controlled system at 50 mm/s that resulted in horizontal abduction. Force that developed passively in the pectoralis major muscle was recorded with an independent uniaxial load cell. Each of the glenohumeral joints dislocated anterior-inferior, six with avulsion of the capsulolabrum from the anterior-inferior glenoid bone and eight with capsulolabral stretching. Pectoralis major muscle force as well as the joint reaction force increased with horizontal abduction until dislocation. At dislocation, the magnitude of the pectoralis major muscle force, 609.6 N +/- 65.2 N was similar to the compression force, 569.6 N +/- 37.8 N. A cadaveric model yielded an anterior dislocation with a mechanism of forcible apprehension positioning when the appropriate shoulder muscles were simulated and a passive pectoralis major muscle was included. Capsulolabral lesions resulted, similar to those observed in vivo.

  16. First-time anterior shoulder dislocations: should they be arthroscopically stabilised?

    PubMed Central

    Sedeek, Sedeek Mohamed; Bin Abd Razak, Hamid Rahmatullah; Ee, Gerard WW; Tan, Andrew HC

    2014-01-01

    The glenohumeral joint is inherently unstable because the large humeral head articulates with the small shadow glenoid fossa. Traumatic anterior dislocation of the shoulder is a relatively common athletic injury, and the high frequency of recurrent instability in young athletes after shoulder dislocation is discouraging to both the patient and the treating physician. Management of primary traumatic shoulder dislocation remains controversial. Traditionally, treatment involves initial immobilisation for 4–6 weeks, followed by functional rehabilitation. However, in view of the high recurrence rates associated with this traditional approach, there has been an escalating interest in determining whether immediate surgical intervention can lower the rate of recurrent shoulder dislocation, improving the patient’s quality of life. This review article aims to provide an overview of the nature and pathogenesis of first-time primary anterior shoulder dislocations, the widely accepted management modalities, and the efficacy of primary surgical intervention in first-time primary anterior shoulder dislocations. PMID:25631890

  17. Neglected bilateral congenital dislocation of the patella.

    PubMed

    Tokgöz, Mehmet Ali; Çavuşoğlu, Ali Turgay; Ayanoğlu, Tacettin; Elma, Tarık; Vural, Abdurrahman

    2017-08-01

    Congenital dislocation of the patella is a disorder that presents with dysfunction in extensor mechanism. Although congenital dislocation of the patella mostly occurs in children with genetic disorders, it may also occur in totally healthy children, despite rarely. In this article, we report a 16-year-old male patient who referred to our clinic with complaints of gait disturbance, frequent falls, and muscular weakness in lower extremity. The patient had no complaints during walking, but had difficulty in running and walking up and down the stairs. It was observed that the range of motion of the knee joint was completely painless and the quadriceps muscle strength was evaluated as 3/5. An evaluation of computed tomography and magnetic resonance imaging results showed that the patella was dislocated. It became clear with magnetic resonance imaging that extensor mechanism was continuous but patellar tendon was not attached to its anatomical position. Surgical treatment was not planned because the patient did not describe any pain complaint and there was no limitation of joint movement, he could walk without support and without device and also refused to be operated. The choice of treatment should be based on the patient's preference, and pain and functional status.

  18. Acute high-grade acromioclavicular dislocations treated with triple button device (MINAR): Preliminary results.

    PubMed

    Cano-Martínez, José Antonio; Nicolás-Serrano, Gregorio; Bento-Gerard, Julio; Picazo-Marín, Francisco; Andrés-Grau, Josefina

    2016-11-01

    Describe the clinical and radiological results of triple button device in the treatment of high-grade AC dislocations (Rockwood, type V) and assess whether improves vertical and horizontal stability compared to the techniques previously described. This retrospective study included 39 patients with type V acromioclavicular dislocations treated with Twin Tail TightRope™ system (triple button device). Of the 39 patients, 33 (26 men and 7 women) were able to participate in clinical and radiographic follow up. At the time of surgery, the mean age was 25years±7(range, 17-49). All patients underwent bilateral-weighted Zanca (CC distance) and Alexander view (AC distance) as well as the Constant Score (CS) and Acromioclavicular Joint Instability Scoring System (ACJI). Radiological and clinical outcome was assessed during routine follow-up examinations preoperatively, postoperatively, 1, 3, 6 months and every year after the surgery. The presence of calcification, degenerative changes, mobilization of implants and bone resorption were also assessed. After a mean follow up of 25±4months (range 14-38), the results of the Constant (CS) were 94.1±5,5 (range 76-100) and test ACJI 87.3±9,8 (range 65-100), showing no significant differences with the uninjured shoulder (CS 95.8±2.5, range 83-100; ACJI 94.1±3.7, range 80-100). At final review, we observed that preoperative coracoclavicular distance (Zanca View) improved from 21,75±1.97mm to 8,73mm±0.75 and the acromioclavicular distance (Alexander View) from 12,65mm±1.99 to 0,35±0.3mm. Compared with healthy shoulder, these differences were not significant. There was no loss of reduction with this system in the vertical plane. 4 patients (12.12%) revealed signs of posterior instability with worse clinical test results. The presence of degenerative joint changes (6,06%), calcifications (27,2%) or mobilization of the implant (18,18%) was not associated with worse clinical outcomes. Twin Tail device using minimally invasive

  19. Ipsilateral fracture dislocation of the shoulder and elbow: A case report and literature review

    PubMed Central

    Behr, Ian; Blint, Andy; Trenhaile, Scott

    2013-01-01

    Ipsilateral dislocation of the shoulder and elbow is an uncommon injury. A literature review identified nine previously described cases. We are reporting a unique case of ipsilateral posterior shoulder dislocation and anterior elbow dislocation along with concomitant intra-articular fractures of both joints. This is the first report describing this combination of injuries. Successful treatment generally occurs with closed reduction of ipsilateral shoulder and elbow dislocations, usually reducing the elbow first. When combined with a fracture at one or both locations, closed reduction of the dislocations in conjunction with appropriate fracture management can result in a positive functional outcome. PMID:26403884

  20. Combined arthroscopically assisted coraco- and acromioclavicular stabilization of acute high-grade acromioclavicular joint separations.

    PubMed

    Hann, Carmen; Kraus, Natascha; Minkus, Marvin; Maziak, Nina; Scheibel, Markus

    2018-01-01

    Due to high rate of persisting dynamic posterior translation (DPT) following isolated coracoclavicular double-button technique for reconstruction of the acromioclavicular (AC) joint reported in the literature, an additional acromioclavicular cerclage was added to the procedure. The aim of this study was to evaluate the clinical and radiological results of patients with high-grade AC-joint instability treated with a double TightRope technique with an additional percutaneous acromioclavicular cerclage. Fifty-nine patients (6 f/53 m; median age 38.3 (range 21.5-63.4 years) who sustained an acute high-grade AC-joint dislocation (Rockwood type V) were treated using the above-mentioned technique. At the final follow-up, the constant score (CS), the subjective shoulder value (SSV), the Taft score (TF) and the acromioclavicular joint instability score (ACJI) as well as bilateral anteroposterior stress views with 10 kg of axial load and bilateral modified Alexander views were obtained. At a median follow-up of 26.4 (range 20.3-61.0) months, 34 patients scored a median of 90 (33-100) points in the CS, 90 (25-100) % in the SSV, 11 (4-12) points in the TF and 87 (43-100) points in the ACJI. The coracoclavicular (CC) distance was 12.1 (6.5-19.8) mm and the CC difference 2.0 (0.0-11.0) mm. Two patients (5.8%) showed a complete DPT of the AC joint, and fourteen patients (41.1%) displayed a partial DPT. The overall revision rate was 11.7%. Two patients presented implant irritation, one patient a recurrent instability, and one patient suffered from a local infection. The arthroscopically assisted and image-intensifier-controlled double TightRope technique with an additional percutaneous acromioclavicular cerclage leads to good and excellent clinical results after a follow-up of 2 years. The incidence of persisting dynamic horizontal translation is lower compared to isolated coracoclavicular stabilization. Thus, we recommend using the double TightRope implant with an additional

  1. Benign joint hypermobility syndrome in soldiers; what is the effect of military training courses on associated joint instabilities?

    PubMed

    Azma, Kamran; Mottaghi, Peyman; Hosseini, Alireza; Abadi, Hossein Hassan; Nouraei, Mohammad Hadi

    2014-07-01

    Hypermobile joints are joints with beyond normal range of motion and may be associated with joint derangements. This study aimed to evaluate the prevalence of benign joint hypermobility syndrome (BJHS) among soldiers and effect of training courses on related joint instabilities. In a prospective cohort study on 721 soldiers of Iran Army in Isfahan in 2013 the prevalence of joint hypermobility was obtained by using Beighton criteria. Soldiers divided in two groups of healthy and suffered based on their scores. The prevalence of ankle sprain, shoulder and temporomandibular joint (TMJ) dislocations identified before beginning service by history-taking and reviewing paraclinical documents. After 3 months of military training, a recent occurrence of mentioned diseases was revaluated in two groups. The collected data were analyzed using SPSS-20 software using Independent-T and Chi-square tests. The frequency of BJHS before military training was 29.4%. After passing military training period, the incidence of ankle sprain was significantly higher in suffered group achieving the minimum Beighton score (BS) of 4 (4.3%, P = 0.03), 5 (5.5%, P = 0.005) and also 6 out of 9 (6.5%, P = 0.01). The incidence of TMJ dislocation was not significantly different based on a minimum score of 4, while it was higher in suffered group when considering the score of 5 (2.1%) and 6 (2.6%) for discrimination of two groups (P = 0.03). There was no significant difference between two groups in case of shoulder dislocation anyway. Military training can increase the incidence of ankle sprains and TMJ dislocations in hypermobility persons with higher BS in comparison with healthy people. Therefore, screening of joint hypermobility may be useful in identifying individuals at increased risk for joint instabilities.

  2. Binary dislocation junction formation and strength in hexagonal close-packed crystals

    DOE PAGES

    Wu, Chi -Chin; Aubry, Sylvie; Arsenlis, Athanasios; ...

    2015-12-17

    This work examines binary dislocation interactions, junction formation and junction strengths in hexagonal close-packed ( hcp ) crystals. Through a line-tension model and dislocation dynamics (DD) simulations, the interaction and dissociation of different sets of binary junctions are investigated involving one dislocation on the (011¯0) prismatic plane and a second dislocation on one of the following planes: (0001) basal, (11¯00) prismatic, (11¯01) primary pyramidal, or (2¯112) secondary pyramidal. Varying pairs of Burgers vectors are chosen from among the common types the basal type < a > 1/3 < 112¯0 >, prismatic type < c > <0001>, and pyramidal type a+c > 1/3 < 112¯3¯ >. For binary interaction due to dislocation intersection, both the analytical results and DD-simulations indicate a relationship between symmetry of interaction maps and the relative magnitude of the Burgers vectors that constitute the junction. Using analytical formulae, a simple regressive model is also developed to represent the junction yield surface. The equation is treated as a degenerated super elliptical equation to quantify the aspect ratio and tilting angle. Lastly, the results provide analytical insights on binary dislocation interactions that may occur in general hcp metals.« less

  3. Biomechanical evaluation of the impact of various facet joint lesions on the primary stability of anterior plate fixation in cervical dislocation injuries: a cadaver study: Laboratory investigation.

    PubMed

    Oberkircher, Ludwig; Born, Sebastian; Struewer, Johannes; Bliemel, Christopher; Buecking, Benjamin; Wack, Christina; Bergmann, Martin; Ruchholtz, Steffen; Krüger, Antonio

    2014-10-01

    Injuries of the subaxial cervical spine including facet joints and posterior ligaments are common. Potential surgical treatments consist of anterior, posterior, or anterior-posterior fixation. Because each approach has its advantages and disadvantages, the best treatment is debated. This biomechanical cadaver study compared the effect of different facet joint injuries on primary stability following anterior plate fixation. Fractures and plate fixation were performed on 15 fresh-frozen intact cervical spines (C3-T1). To simulate a translation-rotation injury in all groups, complete ligament rupture and facet dislocation were simulated by dissecting the entire posterior and anterior ligament complex between C-4 and C-5. In the first group, the facet joints were left intact. In the second group, one facet joint between C-4 and C-5 was removed and the other side was left intact. In the third group, both facet joints between C-4 and C-5 were removed. The authors next performed single-level anterior discectomy and interbody grafting using bone material from the respective thoracic vertebral bodies. An anterior cervical locking plate was used for fixation. Continuous loading was performed using a servohydraulic test bench at 2 N/sec. The mean load failure was measured when the implant failed. In the group in which both facet joints were intact, the mean load failure was 174.6 ± 46.93 N. The mean load failure in the second group where only one facet joint was removed was 127.8 ± 22.83 N. In the group in which both facet joints were removed, the mean load failure was 73.42 ± 32.51 N. There was a significant difference between the first group (both facet joints intact) and the third group (both facet joints removed) (p < 0.05, Kruskal-Wallis test). In this cadaver study, primary stability of anterior plate fixation for dislocation injuries of the subaxial cervical spine was dependent on the presence of the facet joints. If the bone in one or both facet joints is damaged

  4. Dislocations

    MedlinePlus

    ... or a blow, sometimes from playing a contact sport. You can dislocate your ankles, knees, shoulders, hips, ... to dislocate it again. Wearing protective gear during sports may help prevent dislocations.

  5. Superolateral dislocation of an intact mandibular condyle into the temporal fossa: case report and literature review.

    PubMed

    Sharma, Divashree; Khasgiwala, Ankit; Maheshwari, Bharat; Singh, Charanpreet; Shakya, Neelam

    2017-02-01

    Temporomandibular joint dislocation refers to the dislodgement of mandibular condyle from the glenoid fossa. Anterior and anteromedial dislocations of the mandibular condyle are frequently reported in the literature, but superolateral dislocation is a rare presentation. This report outlines a case of superolateral dislocation of an intact mandibular condyle that occurred in conjunction with an ipsilateral mandibular parasymphysis fracture. A review of the clinical features of superolateral dislocation of the mandibular condyle and the possible techniques of its reduction ranging from the most conservative means to extensive surgical interventions is presented. © 2016 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  6. Primary ankle arthrodesis for neglected open Weber B ankle fracture dislocation.

    PubMed

    Thomason, Katherine; Ramesh, Ashwanth; McGoldrick, Niall; Cove, Richard; Walsh, James C; Stephens, Michael M

    2014-01-01

    Primary ankle arthrodesis used to treat a neglected open ankle fracture dislocation is a unique decision. A 63-year-old man presented to the emergency department with a 5-day-old open fracture dislocation of his right ankle. After thorough soft tissue debridement, primary arthrodesis of the tibiotalar joint was performed using initial Kirschner wire fixation and an external fixator. Definitive soft tissue coverage was later achieved using a latissimus dorsi free flap. The fusion was consolidated to salvage the limb from amputation. The use of primary arthrodesis to treat a compound ankle fracture dislocation has not been previously described. Copyright © 2014 American College of Foot and Ankle Surgeons. Published by Elsevier Inc. All rights reserved.

  7. A Rare Case of Neglected Traumatic Anterior Dislocation of Hip in a Child.

    PubMed

    Mootha, Aditya Krishna; Mogali, Kasi Viswanadam

    2016-01-01

    Post traumatic hip dislocations are very rare in children. Neglected anterior hip dislocations in children are not described in literature so far. Here, we present a case of 6 weeks old anterior hip dislocation successfully managed by open reduction. A 9-year-old male child presented with neglected anterior hip dislocation on left side. Open reduction carried out through direct anterior approach to hip. Congruent reduction is achieved. At final follow up of 1 year, the child had unrestricted activities of daily living and no radiological signs of osteonecrosis or any joint space reduction. There is paucity of literature over neglected post traumatic anterior hip dislocations in children. The treatment options vary from closed reduction after heavy traction to sub trochanteric osteotomy. However, we feel that open reduction through direct anterior approach is the preferred mode of management whenever considered possible.

  8. The Power of a Soccer Ball: A Traumatic Open Finger Dislocation-A Rare Case Presentation.

    PubMed

    Dülgeroğlu, Turan Cihan; Metineren, Hasan; Aydın, Ekrem; Dülgeroğlu, Ayşegül

    2015-01-01

    Proximal interphalangeal joint dislocations are injuries observed frequently and caused by axial loading on the finger in the extension. In this paper we present a traumatic open finger dislocation due to a ball hitting a wrestler. It was successfully treated with reduction and the volar plate and collateral bond fixation were applied with absorbable sutures.

  9. Intra-Articular Entrapment of the Medial Epicondyle following a Traumatic Fracture Dislocation of the Elbow in an Adult

    PubMed Central

    Hassan, Youssef G.; Joukhadar, Nabih I.

    2018-01-01

    Medial epicondyle entrapment after an acute fracture dislocation of the elbow is a common finding in the pediatric population, but a rare finding in adults. We present a case of an adult patient diagnosed with a traumatic fracture dislocation of the elbow joint with intra-articular entrapment of the medial epicondyle. After initial evaluation, closed reduction was done. Stability testing after reduction showed an unstable joint; thus, open reduction and internal fixation was decided. PMID:29666736

  10. Singular orientations and faceted motion of dislocations in body-centered cubic crystals.

    PubMed

    Kang, Keonwook; Bulatov, Vasily V; Cai, Wei

    2012-09-18

    Dislocation mobility is a fundamental material property that controls strength and ductility of crystals. An important measure of dislocation mobility is its Peierls stress, i.e., the minimal stress required to move a dislocation at zero temperature. Here we report that, in the body-centered cubic metal tantalum, the Peierls stress as a function of dislocation orientation exhibits fine structure with several singular orientations of high Peierls stress-stress spikes-surrounded by vicinal plateau regions. While the classical Peierls-Nabarro model captures the high Peierls stress of singular orientations, an extension that allows dislocations to bend is necessary to account for the plateau regions. Our results clarify the notion of dislocation kinks as meaningful only for orientations within the plateau regions vicinal to the Peierls stress spikes. These observations lead us to propose a Read-Shockley type classification of dislocation orientations into three distinct classes-special, vicinal, and general-with respect to their Peierls stress and motion mechanisms. We predict that dislocation loops expanding under stress at sufficiently low temperatures, should develop well defined facets corresponding to two special orientations of highest Peierls stress, the screw and the M111 orientations, both moving by kink mechanism. We propose that both the screw and the M111 dislocations are jointly responsible for the yield behavior of BCC metals at low temperatures.

  11. Rehabilitation of neglected Monteggia fracture: Dislocations in children.

    PubMed

    Yıldırım, Azad; Nas, Kemal

    2017-11-06

    There are limited studies related to the rehabilitation of neglected Monteggia fracture-dislocations. This study reports the results of the rehabilitation of neglected Monteggia fractures and dislocations and the best treatment options available. Thirteen children were rehabilitated between 2009 and 2012. A retrospective chart review was conducted to record the following: age, gender, anatomic region of fractures, time delay from symptom onset to fracture, Bado classification, Mayo Elbow Performance Index (MEPI) which includes pain, range of motion and daily life comfort, surgeries, length of hospitalization, location and pattern of fracture, length of follow-up and complications. The study group included thirteen children and adolescents; eleven males and two females with a mean age of 8.5 (range 2-15) years. According to the Bado classification, 11 patients had type 1, one had type 3 and one had type 4 fracture-dislocations. For Mayo Elbow Performance Index (MEPI) scales, patients that were less than ten years old had greater mean scores. Two patients had superficial infection, one had subluxation, one had osteoarthritis, one had delayed bone union and two had rigidity at the elbow. The goals of elbow rehabilitation following Neglected Monteggia cases include restoring function by restoring motion and muscle performance; influencing scar remodeling and preventing joint contracture; and restoring or maintaining joint stability. Patients aged younger than 10 years and intervals of less than one-year, between trauma and diagnosis, as well as early and effective rehabilitation were found as important parameters regarding favorable outcomes.

  12. Short-term outcomes of arthroscopic TightRope® fixation are better than hook plate fixation in acute unstable acromioclavicular joint dislocations.

    PubMed

    Bin Abd Razak, Hamid Rahmatullah; Yeo, Eng-Meng Nicholas; Yeo, William; Lie, Tijauw-Tjoen Denny

    2018-07-01

    The aim of this study was to compare the short-term outcomes of arthroscopic TightRope ® fixation with that of hook plate fixation in patients with acute unstable acromioclavicular joint dislocations. We conducted a prospective case-control study of twenty-six patients with an acute ACJ dislocation who underwent surgical repair with either an arthroscopic TightRope ® fixation or a hook plate from 2013 to 2016. Clinical and radiological data were collected prospectively. Clinical outcomes were evaluated using the Constant Score, the University of California at Los Angeles (UCLA) Shoulder Score, Oxford Shoulder Score as well as the visual analogue scale. Radiological outcomes were assessed with the coracoclavicular distance (CCD). Sixteen patients underwent arthroscopic TightRope ® fixation, while 10 patients underwent hook plate fixation. There were no significant differences in the preoperative variables except for the mean UCLA 4b infraspinatus score (TightRope ® 2.8 vs. hook plate 3.8; p = 0.030). Duration of surgery was significantly longer in the TightRope ® group. At 1 year post-operatively, the TightRope ® group had a significantly better Constant Score and CCD with no complications. All patients with hook plate fixation had to undergo a second procedure for removal of implant, and 3 patients had complications. Arthroscopic TightRope ® fixation is a good option for the treatment of acute unstable ACJ dislocations. It has better short-term clinical and radiological outcomes as well as lesser complications when compared to hook plate fixation. Therapeutic, Level III.

  13. Avulsion fracture of an ossified pes anserinus tendon post-lateral patellar dislocation.

    PubMed

    Albtoush, Omar M; Taib, Abtehag A; Horger, Marius; Springer, Fabian

    2018-05-01

    The pes anserinus is a common tendon comprising the tendinous insertions of the sartorius, gracilis, and semitendinosus muscles. It inserts at the anteromedial aspect of the tibia and plays a significant role in stabilization of the medial side of the knee joint. The current article presents a case with recurrent lateral patellar dislocations causing chronic stress along the medial knee stabilizers and consecutive enthesophyte formation at the insertion of the pes anserinus tendon that showed a transverse fracture upon a subsequent incident of traumatic lateral patellar dislocation. Avulsion injuries of the pes anserinus tendon are rarely encountered, and to our knowledge, association with recurrent lateral patellar dislocations has not been described before.

  14. True congenital dislocation of shoulder: A case report and review of the literature.

    PubMed

    Sudesh, Pebam; Rangdal, Sushil; Bali, Kamal; Kumar, Vishal; Gahlot, Nitesh; Patel, Sandeep

    2010-10-01

    The dislocation of a shoulder joint in infancy is extremely rare and is usually the result of traumatic birth injuries, a sequel to brachial plexus injury, or a true congenital dislocation of shoulder. With more advanced obstetric care, the incidence of first two types has drastically decreased. We report a case of true congenital dislocation of shoulder, second of its kind, in a child who was delivered by cesarean section thereby negating any influence of trauma. We report the case because of its rarity, and review the available literature on this topic. We also discuss the management options when encountered with such a rare case scenario.

  15. Dislocation confinement in the growth of Na flux GaN on metalorganic chemical vapor deposition-GaN

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Takeuchi, S., E-mail: takeuchi@ee.es.osaka-u.ac.jp; Asazu, H.; Nakamura, Y.

    2015-12-28

    We have demonstrated a GaN growth technique in the Na flux method to confine c-, (a+c)-, and a-type dislocations around the interface between a Na flux GaN crystal and a GaN layer grown by metalorganic chemical vapor deposition (MOCVD) on a (0001) sapphire substrate. Transmission electron microscopy (TEM) clearly revealed detailed interface structures and dislocation behaviors that reduced the density of vertically aligned dislocations threading to the Na flux GaN surface. Submicron-scale voids were formed at the interface above the dislocations with a c component in MOCVD-GaN, while no such voids were formed above the a-type dislocations. The penetration ofmore » the dislocations with a c component into Na flux GaN was, in most cases, effectively blocked by the presence of the voids. Although some dislocations with a c component in the MOCVD-GaN penetrated into the Na flux GaN, their propagation direction changed laterally through the voids. On the other hand, the a-type dislocations propagated laterally and collectively near the interface, when these dislocations in the MOCVD-GaN penetrated into the Na flux GaN. These results indicated that the dislocation propagation behavior was highly sensitive to the type of dislocation, but all types of dislocations were confined to within several micrometers region of the Na flux GaN from the interface. The cause of void formation, the role of voids in controlling the dislocation behavior, and the mechanism of lateral and collective dislocation propagation are discussed on the basis of TEM results.« less

  16. Shoulder dislocation in patients older than 60 years of age

    PubMed Central

    Rapariz, Jose M.; Martin-Martin, Silvia; Pareja-Bezares, Antonio; Ortega-Klein, Jose

    2010-01-01

    Purpose: Recurrent anterior shoulder dislocation in elderly patients is a little studied condition. The goal of this paper is to clarify the role of associated injuries with respect to loss of function and recurrence of dislocation. Materials and Methods: We have conducted a retrospective, descriptive study on 29 patients older than 60 years at the moment they suffered their first dislocation episode. All patients were assessed clinically (Constant test) and by imaging testing (X-ray, MRI). Results: Nine (31.03%) out of 29 patients had a recurrent dislocation. Four of them required reconstructive surgery to maintain joint stability. Injury to the anterior support (anterior labrum, anterior glenoid rim) showed a statistically significant relation to the recurrence of dislocations. The occurrence or non-occurrence of a rotator cuff tear does have an impact on the shoulder function. The degree of rotator cuff involvement on the coronal plane does not significantly affect the shoulder’s functional outcome. The tear extension on the sagittal plane does cause impairment on the Constant test. Conclusions: Labrum and/or anterior glenoid involvement should be suspected in elderly patients presenting with recurrent shoulder dislocation. Recurrence is due to an injury in the anterior support or both (anterior and posterior), even though shoulder function gets impaired when a rotation cuff tear occurs with anterior extension on the sagittal plane. Evidence level: IV Case series. PMID:21655003

  17. Controversies in the Management of the First Time Shoulder Dislocation

    PubMed Central

    Avila Lafuente, José Luis; Moros Marco, Santos; García Pequerul, José Manuel

    2017-01-01

    Background: Traditionally, initial management of first anterior shoulder dislocations consists of reduction of the glenohumeral joint followed by a period of immobilization and subsequent physical therapy to recover shoulder range of motion and strength. This traditional approach in management is now controversial due to the high rate of recurrence. The aim of this paper is to review and discuss the literature about the global management of patients presenting with first-time traumatic anterior glenohumeral dislocation, analyzing the factors that affect shoulder instability after the first episode of dislocation. Methods: Scientific publications about the management of first-time shoulder dislocations are reviewed. Pubmed is used for that and no limit in the year of publication are stablished. These papers and their conclusions are discussed. Results: Younger patients, patient´s activities and the kind of injury are the most important factors related to the shoulder instability after a first time traumatic dislocation. Authors that recommend surgical treatment after the first episode of dislocation argue that the possibilities of recurrence are high and therefore surgery should be performed before its occurrence. Other authors, however, argue that surgical treatment is demanding, and keep in mind that complications, such as recurrence, stiffness and pain after surgery, are still present. Conclusion: Currently, there is still no consensus in the literature with regard to the management of first episode of shoulder dislocation. It is necessary to analyze carefully every individual case to manage them more or less aggressive to obtain the best result in our practice. PMID:29430264

  18. Initial dislocation structure and dynamic dislocation multiplication in Mo single crystals

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Hsiung, L M; Lassila, D H

    Initial dislocation structure in annealed high-purity Mo single crystals and deformation substructure in a crystal subjected to 1% compression have been examined and studied in order to investigate dislocation multiplication mechanisms in the early stages of plastic deformation. The initial dislocation density is in a range of 10{sup 6} {approx} 10{sup 7} cm{sup -2}, and the dislocation structure is found to contain many grown-in superjogs along dislocation lines. The dislocation density increases to a range of 10{sup 8} {approx} 10{sup 9} cm{sup -2}, and the average jog height is also found to increase after compressing for a total strain ofmore » 1%. It is proposed that the preexisting jogged screw dislocations can act as (multiple) dislocation multiplication sources when deformed under quasi-static conditions. Both the jog height and length of link segment (between jogs) can increase by stress-induced jog coalescence, which takes place via the lateral migration (drift) of superjogs driven by unbalanced line-tension partials acting on link segments of unequal lengths. Applied shear stress begins to push each link segment to precede dislocation multiplication when link length and jog height are greater than critical lengths. This dynamic dislocation multiplication source is subsequently verified by direct simulations of dislocation dynamics under stress to be crucial in the early stages of plastic deformation in Mo single crystals.« less

  19. Dislocations

    MedlinePlus

    ... Things That Help Feelings Expert Answers Q&A Movies & More for Teens ... A dislocation is when two connected bones become separated. Dislocations are caused by falls and hard impacts, such as in sports injuries, and are more ...

  20. Interaction of 〈1 0 0〉 dislocation loops with dislocations studied by dislocation dynamics in α-iron

    NASA Astrophysics Data System (ADS)

    Shi, X. J.; Dupuy, L.; Devincre, B.; Terentyev, D.; Vincent, L.

    2015-05-01

    Interstitial dislocation loops with Burgers vector of 〈1 0 0〉 type are formed in α-iron under neutron or heavy ion irradiation. As the density and size of these loops increase with radiation dose and temperature, these defects are thought to play a key role in hardening and subsequent embrittlement of iron-based steels. The aim of the present work is to study the pinning strength of the loops on mobile dislocations. Prior to run massive Dislocation Dynamics (DD) simulations involving experimentally representative array of radiation defects and dislocations, the DD code and its parameterization are validated by comparing the individual loop-dislocation reactions with those obtained from direct atomistic Molecular Dynamics (MD) simulations. Several loop-dislocation reaction mechanisms are successfully reproduced as well as the values of the unpinning stress to detach mobile dislocations from the defects.

  1. [Staple fixation for the treatment of hamate metacarpal joint injury].

    PubMed

    Tang, Yang-Hua; Zeng, Lin-Ru; Huang, Zhong-Ming; Yue, Zhen-Shuang; Xin, Da-Wei; Xu, Can-Da

    2014-03-01

    To investigate the effcacy of the staple fixation for the treatment of hamate metacarpal joint injury. From May 2009 to November 2012,16 patients with hamate metacarpal joint injury were treated with staple fixation including 10 males and 6 females with an average age of 33.6 years old ranging from 21 to 57 years. Among them, 11 cases were on the fourth or fifth metacarpal base dislocation without fractures, 5 cases were the fourth or fifth metacarpal base dislocation with avulsion fractures of the back of hamatum. Regular X-ray review was used to observe the fracture healing, joint replacement and position of staple fixation. The function of carpometacarpal joint and metacarpophalangeal joint were evaluated according to ASIA (TAM) system evaluation method. All incision were healed well with no infection. All patients were followed up from 16 to 24 months with an average of (10.0 +/- 2.7) months. No dislocation recurred, the position of internal fixator was good,no broken nail and screw withdrawal were occurred. Five patients with avulsion fracture of the back of hamatum achieved bone healing. The function of carpometacarpal joint and metacarpophalangeal was excellent in 10 cases,good in 5 cases, moderate in 1 case. The application of the staple for the treatment of hamatometacarpal joint injury has the advantages of simple operation, small trauma, reliable fixation, early postoperative function exercise and other advantages, which is the ideal operation mode for hamatometacarpal joint injury.

  2. [Concomitant injuries after upper ankle joint dislocations].

    PubMed

    Dann, K; Wahler, G; Neubauer, N; Steiner, R; Titze, W; Wagner, M

    1996-09-01

    Functional treatment with the Air Stirrup Ankle Brace recommended by C. N. Stover in 1979 can reduce pathological inversion of the ankle joint. In our retrospective study of 109 patients treated by this kind of ankle brace we found 96 patients (88%) with excellent results. Only 13 patients (12%) reported moderate to good results. To detect and characterize their painful conditions of ankles we did a clinical, radiological and MRI-Investigation. In only 2 cases we found a moderate instability after clinical investigation, anterior stress roentgenogram and talar tilt. By using the MRI-investigation 1.0 Tesla with a 512 x 360 Matrix we could find 10 cases with osteochondral lesions of the ankle. In 7 cases there was separated ossicle in the fibulotalar joint, in 1 case we detected a fracture of the processus anterior tali, in another case we could see a posttraumatic lesion of the talus and calcaneus with bone bruise and at least one osteochondral fracture of the distal tibia. The capability of the MRI to detect particularly osteo-chondral lesions of the talus and the tibiofibular joint was shown in 10 of 13 cases. Therefore we recommend to do an MRI-investigation on all patients after ankle sprain if there are painful conditions within the ankle after conservative treatment.

  3. Surgical Approaches to the Proximal Interphalangeal Joint.

    PubMed

    Cheah, Andre Eu-Jin; Yao, Jeffrey

    2016-02-01

    The proximal interphalangeal (PIP) joint may be affected by many conditions such as arthropathy, fractures, dislocations, and malunions. Whereas some of these conditions may be treated nonsurgically, many require open surgical intervention. Open interventions include implant arthroplasty or arthrodesis for arthropathy, open reduction internal fixation, or hemi-hamate arthroplasty for dorsal fracture-dislocations. Volar plate arthroplasty and corrective osteotomy for malunion about the PIP joint are also surgeries that may be required. The traditional approach to the PIP joint has been dorsal, which damages the delicate extensor apparatus with subsequent development of an extensor lag. This has led surgeons to explore volar and lateral approaches to the PIP joint. In this article, we describe each of these surgical approaches, discuss their advantages and disadvantages, and provide some guidance on which approach to choose based on the surgery that is to be performed. Copyright © 2016 American Society for Surgery of the Hand. Published by Elsevier Inc. All rights reserved.

  4. Fracture dislocation of the mandibular condyle; a report of a case

    PubMed Central

    Mierau, Dale; Cassidy, J. David; Nykoliation, Jim

    1985-01-01

    A case report is presented in which discussion centers about a 26 year old male who complained of left sided neck and facial pain, mid-dorsal pain and right jaw pain associated with headaches. Investigation revealed a fracture dislocation of his right temporomandibular joint. The need for the chiropractor to x-ray patients with similar complaints is highlighted and the natural history of temporomandibular joint pain dysfunction syndrome (TMJ-PDS) is reviewed with attention to assessment. ImagesFigure 1Figure 2

  5. Timing of Surgical Reduction and Stabilization of Talus Fracture-Dislocations.

    PubMed

    Buckwalter V, Joseph A; Westermann, Robert; Mooers, Brian; Karam, Matthew; Wolf, Brian

    Talus fractures with associated dislocations are rare but have high rates of complications, including avascular necrosis (AVN). Management of these injuries involves urgent surgical reduction and fixation, although there are no definitive data defining an operative time frame for preserving the blood supply and preventing complications. To determine the effect of time to surgical reduction of talus fractures and talus fracture-dislocations on rates of AVN and posttraumatic osteoarthritis (PTOA), we retrospectively reviewed talus fractures surgically managed at a level I trauma center during the 10-year period 2003 to 2013. Operative reports were obtained and reviewed, and 3 independent reviewers, using the Hawkins and AO/OTA (Arbeitsgemeinschaft für Osteosynthesefragen/Orthopaedic Trauma Association) systems, classified the injuries on plain radiographs. Analysis of AO/OTA 81 fractures with associated tibiotalar, subtalar, or talonavicular dislocations was performed. Primary outcomes were presence of AVN/PTOA and subsequent arthrodesis of tibiotalar or subtalar joints. We identified 106 surgically managed talus fractures. Rates of AVN/PTOA were 41% for all talus fractures and 50% for talus fracture-dislocations. Mean time to surgical reduction was not significant for development of AVN/PTOA for all talus fractures (P = .45) or talus fracture-dislocations (P = .29). There was no difference in age (P = .20), body mass index (P = .45), or polytrauma (P = .79) between patients who developed AVN and those who did not. Open fractures were significantly correlated with the development of AVN/PTOA (P = .009). Talar fracture-dislocations are devastating injuries with high rates of complications. Our data suggest there is no effect of time from injury to surgical reduction of talus fractures or talus fracture-dislocations on rates of AVN and PTOA.

  6. 21 CFR 888.3480 - Knee joint femorotibial metallic constrained cemented prosthesis.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Knee joint femorotibial metallic constrained... Knee joint femorotibial metallic constrained cemented prosthesis. (a) Identification. A knee joint... knee joint. The device prevents dislocation in more than one anatomic plane and has components that are...

  7. A modified technique of reconstruction for complete acromioclavicular dislocation: a prospective study.

    PubMed

    Tienen, Tony G; Oyen, Jan F C H; Eggen, Peter J G M

    2003-01-01

    Many procedures, both nonoperative and operative, have been described for treatment of complete acromioclavicular dislocations. The best primary treatment, however, still remains unclear. We present a new surgical technique in which the clavicle is reduced to an anatomic position, the coracoacromial ligament is transferred to the clavicle, and acromioclavicular joint fixation is accomplished with the use of absorbable, braided suture cord. Twenty-one patients underwent the modified technique of reconstruction. Patients were included only if they had sustained a Rockwood type V acromioclavicular dislocation and were extremely active in competitive sports before dislocation occurred. Eighteen patients returned to their sports without pain within 2.5 months after operation. The mean follow-up was 35.7 months. The average Constant score at last follow-up was 97. Radiographs taken at this time confirmed anatomic reduction in 18 patients, residual subluxation in 2 patients, and, in 1 patient, redislocation of the joint that occurred because of infection. Six patients had radiographic evidence of coracoclavicular ossifications. All patients developed a wide scar. Considering its operative simplicity, the advantage of absorbable augmentation of the clavicular reduction, and the low rate of recurrence, this technique may be an attractive alternative in this particular group of patients.

  8. Scaphocapitate Syndrome With Associated Trans-Scaphoid, Trans-Hamate Perilunate Dislocation

    PubMed Central

    Nunez, Fiesky A.; Luo, T. David; Jupiter, Jesse B.; Nunez, Fiesky A.

    2016-01-01

    Background: Perilunate fracture dislocations are often associated with fractures of the distal pole of the scaphoid or the proximal pole of the capitate. However, the combination of perilunate dislocation with multiple carpal fractures and associated scaphocapitate syndrome is very rare. Methods: We report a unique case of scaphocapitate fracture syndrome with perilunate dislocation and fracture of the hamate resulting from a high-energy injury to the wrist during a dirt-bike competition. Results: Open reduction and internal fixation of the scaphoid fracture with a 3.0-mm headless screw, the head of the capitate with a 1.5-mm lag screw, and the hamate fracture with a 1.3-mm lag screw was performed. The lunotriquetral dissociation was reduced, with the ligament repaired and the joint stabilized using a Kirschner wire. All screw heads are carefully buried under the articulate cartilage. Conclusions: Prompt anatomic reduction and stable osteosynthesis of all fractures in this patient resulted in successful healing and return to activity. PMID:28344539

  9. Biomechanical evaluation of native acromioclavicular joint ligaments and two reconstruction techniques in the presence of the sternoclavicular joint: A cadaver study.

    PubMed

    Masionis, Povilas; Šatkauskas, Igoris; Mikelevičius, Vytautas; Ryliškis, Sigitas; Bučinskas, Vytautas; Griškevičius, Julius; Martin Oliva, Xavier; Monzó Planella, Mariano; Porvaneckas, Narūnas; Uvarovas, Valentinas

    2017-01-01

    Where is over 100 reconstruction techniques described for acromioclavicular (AC) joint reconstruction. Although, it is not clear whether the presence of the sternoclavicular (SC) joint influences the biomechanical properties of native AC ligaments and reconstruction techniques. The purpose of the present study was to investigate the biomechanical properties of native AC joint ligaments and two reconstruction techniques in cadavers with the SC joint still present. We tested eight fresh-frozen cadaver hemithoraces for superior translation (70 N load) and translation increment after 1000 cycles (loading from 20 to 70 N) in a controlled laboratory study. There were three testing groups created: native ligaments, the single coracoclavicular loop (SCL) technique, and the two coracoclavicular loops (TCL) technique. Superior translation was measured after static loading. Translation increment was calculated as the difference between superior translation after cyclic and static loading. Native AC ligaments showed significantly lower translation than the SCL ( p = 0.023) and TCL ( p = 0.046) groups. The SCL had a significantly lower translation increment than native AC ligaments ( p = 0.028). There was no significant difference between reconstruction techniques in terms of translation ( p = 0.865) and translation increment ( p = 0.113). Native AC joint ligaments had better static properties than both reconstruction techniques and worse dynamic biomechanical properties than the SCL technique. The SCL technique appeared to be more secure than the TCL technique. The presence of the SC joint did not have an observable influence on test results.

  10. Late dislocation of rotating platform in New Jersey Low-Contact Stress knee prosthesis.

    PubMed

    Huang, Chun-Hsiung; Ma, Hon-Ming; Liau, Jiann-Jong; Ho, Fang-Yuan; Cheng, Cheng-Kung

    2002-12-01

    Five patients with late rotational dislocation of the rotating platform bearing in the New Jersey Low-Contact Stress total knee arthroplasty are reported. The prostheses had functioned well for 8 to 12 years before failure. Preoperative radiographs showed asymmetric femorotibial joint spaces. Entrapment of the dislocated bearing in three patients and spontaneous reduction of the dislocated bearing in another two patients were seen at revision. Femorotibial ligamentous instability was found after reduction. The retrieved polyethylene bearings showed advanced wear and cold flow deformities and the thickness was reduced. The revision arthroplasty was accomplished by replacement with a thicker bearing element. Progressive femorotibial ligament laxity and reduction of the thickness of polyethylene with wearing break down the originally well-balanced soft tissue tension of the knee. The rotational degree of the rotating platform bearing is unrestricted, which may result in late dislocation. Polyethylene wear is unavoidable in knee prostheses using metal contact with polyethylene even with a mobile-bearing design. Efforts to reduce polyethylene wear are mandatory.

  11. Talocrural Dislocation With Associated Weber Type C Fibular Fracture in a Collegiate Football Player: A Case Report

    PubMed Central

    Ricci, R Daniel; Cerullo, James; Blanc, Robert O; McMahon, Patrick J; Buoncritiani, Anthony M; Stone, David A; Fu, Freddie H

    2008-01-01

    Objective: To present the case of a talocrural dislocation with a Weber type C fibular fracture in a National Collegiate Athletic Association Division I football athlete. Background: The athlete, while attempting to make a tackle during a game, collided with an opponent, who in turn stepped on the lateral aspect of the athlete's ankle, resulting in forced ankle eversion and external rotation. On-field evaluation showed a laterally displaced talocrural dislocation. Immediate reduction was performed in the athletic training room to maintain skin integrity. Post-reduction radiographs revealed a Weber type C fibular fracture and increased medial joint clear space. A below-knee, fiberglass splint was applied to stabilize the ankle joint complex. Differential Diagnosis: Subtalar dislocation, Maisonneuve fracture, malleolar fracture, deltoid ligament rupture, syndesmosis disruption. Treatment: The sports medicine staff immediately splinted and transported the athlete to the athletic training room to reduce the dislocation. The athlete then underwent an open reduction and internal fixation procedure to stabilize the injury: 2 syndesmosis screws and a fibular plate were placed to keep the ankle joint in an anatomically reduced position. With the guidance of the athletic training staff, the athlete underwent an accelerated physical rehabilitation protocol in an effort to return to sport as quickly and safely as possible. Uniqueness: Most talocrural dislocations and associated Weber type C fibular fractures are due to motor vehicle accidents or falls. We are the first to describe this injury in a Division I football player and to present a general rehabilitation protocol for a high-level athlete. Conclusions: Sports medicine practitioners must recognize that this injury can occur in the athletic environment. Prompt reduction, early surgical intervention, sufficient resources, and an accelerated rehabilitation protocol all contributed to a successful outcome in the patient

  12. A combined technique for acromioclavicular reconstruction after acute dislocation - technical description and functional outcomes.

    PubMed

    Moura, Diogo Lino; Reis E Reis, Augusto; Ferreira, João; Capelão, Manuel; Braz Cardoso, José

    2018-01-01

    This study aims to describe the surgical approach to such injuries and to present the clinical and functional outcomes obtained in a cohort of patients. This is an observational retrospective study that included 153 patients with acute acromioclavicular joint dislocation, operated between 1999 and 2015. Clinical evaluation included the following outcomes: Constant functional scale, development of complications, time to return to previous work/sport activities, and satisfaction index. The contra-lateral (uninjured) shoulder was used as control in subjective outcomes. Radiological evaluation was performed in order to monitor signs of loss of reduction, degenerative joint changes, and coracoclavicular calcifications. The mean age was 29.20 ± 9.53 (16-71), with a large male predominance (91.5%). Follow-up lasted 55.41 ± 24.87 (12-108) months. The mean Constant score attained was 96.45 ± 4.00 (84-100) on operated shoulders and 98.28 ± 1.81 (93-100) on contralateral ones. Almost all patients (98.69%) were satisfied with the surgical results. Worse outcomes were observed in acromioclavicular joint dislocations of increasing grade (from type III to V, but worse for type IV), both concerning the Constant score and return to work or sport. The overall incidence of complications was considered low, with the most prevalent being Kirschner wire failure and isolated coracoclavicular ligament calcifications. The surgical technique described is an excellent option in the treatment of acute acromioclavicular joint dislocations of Rockwood grades III to V. This is corroborated by the excellent clinical and functional outcomes and the low rate of complications.

  13. Atlantoaxial manual realignment in a patient with traumatic atlantoaxial joint disruption.

    PubMed

    Goel, Atul; Figueiredo, Antonio; Maheshwari, Shradha; Shah, Abhidha

    2010-05-01

    We report a patient with complex traumatic translatory atlantoaxial dislocation, who we treated by joint exposure and reduction of the dislocation by facet manipulation and subsequent plate and screw atlantoaxial fixation. A 28-year-old male had fallen 7.6m (25 feet), and following the fall had severe neck pain but no neurological deficit. Investigations revealed a fracture at the base of the odontoid process and posterior displacement of the entire atlas over the axis, resulting in a translatory atlantoaxial dislocation. Head traction failed as he developed severe vertigo following its application. The patient was operated upon in a prone position. We opened the atlantoaxial joint and realigned the facets using distraction and manipulation techniques and secured the joint using a plate and screw interarticular method. The patient tolerated the treatment well and was symptom-free after 28 months. Postoperative images showed good craniovertebral alignment. Although technically challenging, direct manipulation of the facets of the atlas and axis can result in excellent craniovertebral realignment.

  14. Estimation of dislocations density and distribution of dislocations during ECAP-Conform process

    NASA Astrophysics Data System (ADS)

    Derakhshan, Jaber Fakhimi; Parsa, Mohammad Habibi; Ayati, Vahid; Jafarian, Hamidreza

    2018-01-01

    Dislocation density of coarse grain aluminum AA1100 alloy (140 µm) that was severely deformed by Equal Channel Angular Pressing-Conform (ECAP-Conform) are studied at various stages of the process by electron backscattering diffraction (EBSD) method. The geometrically necessary dislocations (GNDs) density and statistically stored dislocations (SSDs) densities were estimate. Then the total dislocations densities are calculated and the dislocation distributions are presented as the contour maps. Estimated average dislocations density for annealed of about 2×1012 m-2 increases to 4×1013 m-2 at the middle of the groove (135° from the entrance), and they reach to 6.4×1013 m-2 at the end of groove just before ECAP region. Calculated average dislocations density for one pass severely deformed Al sample reached to 6.2×1014 m-2. At micrometer scale the behavior of metals especially mechanical properties largely depend on the dislocation density and dislocation distribution. So, yield stresses at different conditions were estimated based on the calculated dislocation densities. Then estimated yield stresses were compared with experimental results and good agreements were found. Although grain size of material did not clearly change, yield stress shown intensive increase due to the development of cell structure. A considerable increase in dislocations density in this process is a good justification for forming subgrains and cell structures during process which it can be reason of increasing in yield stress.

  15. Discrete Dislocation Modeling of Fatigue

    NASA Astrophysics Data System (ADS)

    Needleman, Alan

    2004-03-01

    In joint work with V.S. Deshpande of Cambridge University and E. Van der Giessen of the University of Groningen a framework has been developed for the analysis of crack growth under cyclic loading conditions where plastic flow arises from the motion of large numbers of discrete dislocations and the fracture properties are embedded in a cohesive surface constitutive relation. The material model is independent of the presence of a crack and the only distinction between an analysis of monotonic crack growth and fatigue crack growth is that in fatigue the remote loading is specified to be an oscillating function of time. Thus, a basic question is: within this framework, do cracks grow at a lower driving force under cyclic loading than under monotonic loading, and if so, what features of fatigue crack growth emerge? Fatigue does emerge from the calculations as a consequence of the evolution of internal stresses associated with the irreversibility of the dislocation motion. A fatigue threshold, Paris law behavior, striations and the accelerated growth of short cracks are outcomes of the simulations. Also, scaling predictions obtained for the fatigue threshold and the fatigue crack growth rate are discussed.

  16. Chondrodysplasia with multiple dislocations: comprehensive study of a series of 30 cases.

    PubMed

    Ranza, E; Huber, C; Levin, N; Baujat, G; Bole-Feysot, C; Nitschke, P; Masson, C; Alanay, Y; Al-Gazali, L; Bitoun, P; Boute, O; Campeau, P; Coubes, C; McEntagart, M; Elcioglu, N; Faivre, L; Gezdirici, A; Johnson, D; Mihci, E; Nur, B G; Perrin, L; Quelin, C; Terhal, P; Tuysuz, B; Cormier-Daire, V

    2017-06-01

    The group of chondrodysplasia with multiple dislocations includes several entities, characterized by short stature, dislocation of large joints, hand and/or vertebral anomalies. Other features, such as epiphyseal or metaphyseal changes, cleft palate, intellectual disability are also often part of the phenotype. In addition, several conditions with overlapping features are related to this group and broaden the spectrum. The majority of these disorders have been linked to pathogenic variants in genes encoding proteins implicated in the synthesis or sulfation of proteoglycans (PG). In a series of 30 patients with multiple dislocations, we have performed exome sequencing and subsequent targeted analysis of 15 genes, implicated in chondrodysplasia with multiple dislocations, and related conditions. We have identified causative pathogenic variants in 60% of patients (18/30); when a clinical diagnosis was suspected, this was molecularly confirmed in 53% of cases. Forty percent of patients remain without molecular etiology. Pathogenic variants in genes implicated in PG synthesis are of major importance in chondrodysplasia with multiple dislocations and related conditions. The combination of hand features, growth failure severity, radiological aspects of long bones and of vertebrae allowed discrimination among the different conditions. We propose key diagnostic clues to the clinician. © 2016 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  17. Multiscale modeling of dislocation-precipitate interactions in Fe: From molecular dynamics to discrete dislocations.

    PubMed

    Lehtinen, Arttu; Granberg, Fredric; Laurson, Lasse; Nordlund, Kai; Alava, Mikko J

    2016-01-01

    The stress-driven motion of dislocations in crystalline solids, and thus the ensuing plastic deformation process, is greatly influenced by the presence or absence of various pointlike defects such as precipitates or solute atoms. These defects act as obstacles for dislocation motion and hence affect the mechanical properties of the material. Here we combine molecular dynamics studies with three-dimensional discrete dislocation dynamics simulations in order to model the interaction between different kinds of precipitates and a 1/2〈111〉{110} edge dislocation in BCC iron. We have implemented immobile spherical precipitates into the ParaDis discrete dislocation dynamics code, with the dislocations interacting with the precipitates via a Gaussian potential, generating a normal force acting on the dislocation segments. The parameters used in the discrete dislocation dynamics simulations for the precipitate potential, the dislocation mobility, shear modulus, and dislocation core energy are obtained from molecular dynamics simulations. We compare the critical stresses needed to unpin the dislocation from the precipitate in molecular dynamics and discrete dislocation dynamics simulations in order to fit the two methods together and discuss the variety of the relevant pinning and depinning mechanisms.

  18. PCC/AC shoulder joint seal evaluation

    DOT National Transportation Integrated Search

    1999-05-07

    This report presents the findings on the evaluation of Crafco Incorporated Roadsaver 903 SL Silicone Sealant and Dow Corning 890 SL Silicone Sealant. The Research Technical Panel had proposed to use the two self-leveling silicone joint sealants in te...

  19. The ACS NSQIP Risk Calculator Is a Fair Predictor of Acute Periprosthetic Joint Infection.

    PubMed

    Wingert, Nathaniel C; Gotoff, James; Parrilla, Edgardo; Gotoff, Robert; Hou, Laura; Ghanem, Elie

    2016-07-01

    Periprosthetic joint infection (PJI) is a severe complication from the patient's perspective and an expensive one in a value-driven healthcare model. Risk stratification can help identify those patients who may have risk factors for complications that can be mitigated in advance of elective surgery. Although numerous surgical risk calculators have been created, their accuracy in predicting outcomes, specifically PJI, has not been tested. (1) How accurate is the American College of Surgeons National Surgical Quality Improvement Program (ACS NSQIP) Surgical Site Infection Calculator in predicting 30-day postoperative infection? (2) How accurate is the calculator in predicting 90-day postoperative infection? We isolated 1536 patients who underwent 1620 primary THAs and TKAs at our institution during 2011 to 2013. Minimum followup was 90 days. The ACS NSQIP Surgical Risk Calculator was assessed in its ability to predict acute PJI within 30 and 90 days postoperatively. Patients who underwent a repeat surgical procedure within 90 days of the index arthroplasty and in whom at least one positive intraoperative culture was obtained at time of reoperation were considered to have PJI. A total of 19 cases of PJI were identified, including 11 at 30 days and an additional eight instances by 90 days postoperatively. Patient-specific risk probabilities for PJI based on demographics and comorbidities were recorded from the ACS NSQIP Surgical Risk Calculator website. The area under the curve (AUC) for receiver operating characteristic (ROC) curves was calculated to determine the predictability of the risk probability for PJI. The AUC is an effective method for quantifying the discriminatory capacity of a diagnostic test to correctly classify patients with and without infection in which it is defined as excellent (AUC 0.9-1), good (AUC 0.8-0.89), fair (AUC 0.7-0.79), poor (AUC 0.6-0.69), or fail/no discriminatory capacity (AUC 0.5-0.59). A p value of < 0.05 was considered to be

  20. Simultaneous bilateral elbow dislocation with bilateral medial epicondyle fractures in a 13-year-old female gymnast with hyperlaxity

    PubMed Central

    Bauer, Stefan; Dunne, Ben; Whitewood, Colin

    2012-01-01

    Bilateral simultaneous elbow dislocations are extremely rare and have only been described in 12 cases. In the paediatric population unilateral elbow dislocations are rare with 3–6% of all elbow injuries and there are only few studies describing this injury exclusively in children. There is only one case report of a paediatric patient who sustained a simultaneous bilateral elbow dislocation with medial epicondyle fractures. We present a second paediatric case of simultaneous bilateral elbow dislocation with associated displaced bilateral medial epicondyle fractures in a gymnast with joint hyperlaxity (3 of 5 Wynne-Davies criteria) treated with closed reduction and short-term immobilisation (3 weeks). The patient returned to full trampoline gymnastics between 4 and 5 months postinjury and made an uneventful recovery. PMID:23234820

  1. Modified rerouting procedure for failed peroneal tendon dislocation surgery.

    PubMed

    Gaulke, R; Hildebrand, F; Panzica, M; Hüfner, T; Krettek, C

    2010-04-01

    Recurrent dislocation of the peroneal tendons following operative treatment is relatively uncommon, but can be difficult to treat. We asked whether subligamental transposition of the peroneus brevis tendon, fibular grooving, and reattachment of the superior peroneal retinaculum for failed peroneal tendon dislocation surgery would achieve a stable fixation of the peroneal tendons and whether there would be restrictions of ROM or instability of the hindfoot. We reviewed six female patients (mean age, 24.5 years) with general laxity of joints preoperatively and at 6 weeks and 3, 6, and 12 months postoperatively. Within 1 year postoperatively no recurrence was found. In two ankles the extension was restricted 5 degrees to 10 degrees . In another pronation and supination was restricted 5 degrees each. Stability of the ankle increased in four patients and stayed unchanged in two. AOFAS score increased from a mean value of 36 +/- 20.6 preoperatively to 90 +/- 7 postoperatively at 1 year. We conclude transposition of the peroneus brevis tendon is a reasonable treatment for failed peroneal tendon dislocation surgery. Level IV, therapeutic study (prospective case series). See Guidelines for Authors for a complete description of levels of evidence.

  2. Dislocation-induced stress in polycrystalline materials: mesoscopic simulations in the dislocation density formalism

    NASA Astrophysics Data System (ADS)

    Berkov, D. V.; Gorn, N. L.

    2018-06-01

    In this paper we present a simple and effective numerical method which allows a fast Fourier transformation-based evaluation of stress generated by dislocations with arbitrary directions and Burgers vectors if the (site-dependent) dislocation density is known. Our method allows the evaluation of the dislocation stress using a rectangular grid with shape-anisotropic discretization cells without employing higher multipole moments of the dislocation interaction coefficients. Using the proposed method, we first simulate the stress created by relatively simple non-homogeneous distributions of vertical edge and so-called ‘mixed’ dislocations in a disk-shaped sample, which is necessary to understand the dislocation behavior in more complicated systems. The main part of our research is devoted to the stress distribution in polycrystalline layers with the dislocation density rapidly varying with the distance to the layer bottom. Considering GaN as a typical example of such systems, we investigate dislocation-induced stress for edge and mixed dislocations, having random orientations of Burgers vectors among crystal grains. We show that the rapid decay of the dislocation density leads to many highly non-trivial features of the stress distributions in such layers and study in detail the dependence of these features on the average grain size. Finally we develop an analytical approach which allows us to predict the evolution of the stress variance with the grain size and compare analytical predictions with numerical results.

  3. [Fractures of the proximal interphalangeal joint: Diagnostic and operative therapy options].

    PubMed

    Unglaub, F; Langer, M F; Hahn, P; Müller, L P; Ahrens, C; Spies, C K

    2016-02-01

    Joint fractures of the fingers often entail operative interventions in contrast to extra-articular fractures. These types of fracture are inclined to dislocate in addition to the actual fracture. The proximal interphalangeal (PIP) joint in particular often shows comminuted fractures due to the long leverage of the finger and a relatively small diameter of the joint. The clinical examination, X-ray diagnostics and if necessary computed tomography allow the classification into stable and unstable fractures. Unstable fractures must be treated by surgical reduction and fixation. A multitude of operative techniques are available for these mostly complicated fractures. The foremost goal is a stable osteosynthesis of the fracture with repositioning of the dislocation, which enables early physiotherapy in order to prevent tendon adhesion and contracture. This article presents the different types of PIP joint fractures, their specific surgical treatment and postoperative treatment regimens.

  4. Resident accuracy of joint line palpation using ultrasound verification.

    PubMed

    Rho, Monica E; Chu, Samuel K; Yang, Aaron; Hameed, Farah; Lin, Cindy Yuchin; Hurh, Peter J

    2014-10-01

    To determine the accuracy of knee and acromioclavicular (AC) joint line palpation in Physical Medicine and Rehabilitation (PM&R) residents using ultrasound (US) verification. Cohort study. PM&R residency program at an academic institution. Twenty-four PM&R residents participating in a musculoskeletal US course (7 PGY-2, 8 PGY-3, and 9 PGY4 residents). Twenty-four PM&R residents participating in an US course were asked to palpate the AC joint and lateral joint line of the knee in a female and male model before the start of the course. Once the presumed joint line was localized, the residents were asked to tape an 18-gauge, 1.5-inch, blunt-tip needle parallel to the joint line on the overlying skin. The accuracy of needle placement over the joint line was verified using US. US verification of correct needle placement over the joint line. Overall AC joint palpation accuracy was 16.7%, and knee lateral joint line palpation accuracy was 58.3%. Based on the resident level of education, using a value of P < .05, there were no statistically significant differences in the accuracy of joint line palpation. Residents in this study demonstrate poor accuracy of AC joint and lateral knee joint line identification by palpation, using US as the criterion standard for verification. There were no statistically significant differences in the accuracy rates of joint line palpation based on resident level of education. US may be a useful tool to use to advance the current methods of teaching the physical examination in medical education. Copyright © 2014 American Academy of Physical Medicine and Rehabilitation. Published by Elsevier Inc. All rights reserved.

  5. Acromioclavicular dislocation: treatment and rehabilitation. Current perspectives and trends among Brazilian orthopedists☆

    PubMed Central

    Arliani, Gustavo Gonçalves; Utino, Artur Yudi; Nishimura, Eduardo Misao; Terra, Bernardo Barcellos; Belangero, Paulo Santoro; Astur, Diego Costa

    2015-01-01

    Objective To evaluate the approaches and procedures used by Brazilian orthopedic surgeons in treatment and rehabilitation of acromioclavicular dislocation of the shoulder. Methods A questionnaire comprising eight closed questions that addressed topics relating to treatment and rehabilitation of acromioclavicular dislocation was applied to Brazilian orthopedic surgeons over the three days of the 45th Brazilian Congress of Orthopedics and Traumatology, in 2013. Results A total of 122 surgeons completely filled out the questionnaire and formed part of the sample analyzed. Most of them came from the southeastern region of the country. In this sample, 67% of the participants would choose surgical treatment for patients with grade 3 acromioclavicular dislocation. Regarding the preferred technique for surgical treatment of acute acromioclavicular dislocation, a majority of the surgeons used subcoracoid ligature with acromioclavicular fixation and transfer of the coracoacromial ligament (25.4%). Regarding complications found after surgery had been performed, 43.4% and 32.8% of the participants, respectively, stated that residual deformity of the operated joint and pain were the complications most seen during the postoperative period. Conclusions Although there was no consensus regarding the treatment and rehabilitation of acromioclavicular dislocation, evolution had occurred in some of the topics analyzed in this questionnaire applied to Brazilian orthopedists. However, further controlled prospective studies are needed in order to evaluate the clinical and scientific benefit of these trends. PMID:26535196

  6. Acromioclavicular dislocation: treatment and rehabilitation. Current perspectives and trends among Brazilian orthopedists.

    PubMed

    Arliani, Gustavo Gonçalves; Utino, Artur Yudi; Nishimura, Eduardo Misao; Terra, Bernardo Barcellos; Belangero, Paulo Santoro; Astur, Diego Costa

    2015-01-01

    To evaluate the approaches and procedures used by Brazilian orthopedic surgeons in treatment and rehabilitation of acromioclavicular dislocation of the shoulder. A questionnaire comprising eight closed questions that addressed topics relating to treatment and rehabilitation of acromioclavicular dislocation was applied to Brazilian orthopedic surgeons over the three days of the 45th Brazilian Congress of Orthopedics and Traumatology, in 2013. A total of 122 surgeons completely filled out the questionnaire and formed part of the sample analyzed. Most of them came from the southeastern region of the country. In this sample, 67% of the participants would choose surgical treatment for patients with grade 3 acromioclavicular dislocation. Regarding the preferred technique for surgical treatment of acute acromioclavicular dislocation, a majority of the surgeons used subcoracoid ligature with acromioclavicular fixation and transfer of the coracoacromial ligament (25.4%). Regarding complications found after surgery had been performed, 43.4% and 32.8% of the participants, respectively, stated that residual deformity of the operated joint and pain were the complications most seen during the postoperative period. Although there was no consensus regarding the treatment and rehabilitation of acromioclavicular dislocation, evolution had occurred in some of the topics analyzed in this questionnaire applied to Brazilian orthopedists. However, further controlled prospective studies are needed in order to evaluate the clinical and scientific benefit of these trends.

  7. Glide dislocation nucleation from dislocation nodes at semi-coherent {111} Cu–Ni interfaces

    DOE PAGES

    Shao, Shuai; Wang, Jian; Beyerlein, Irene J.; ...

    2015-07-23

    Using atomistic simulations and dislocation theory on a model system of semi-coherent {1 1 1} interfaces, we show that misfit dislocation nodes adopt multiple atomic arrangements corresponding to the creation and redistribution of excess volume at the nodes. We identified four distinctive node structures: volume-smeared nodes with (i) spiral or (ii) straight dislocation patterns, and volume-condensed nodes with (iii) triangular or (iv) hexagonal dislocation patterns. Volume-smeared nodes contain interfacial dislocations lying in the Cu–Ni interface but volume-condensed nodes contain two sets of interfacial dislocations in the two adjacent interfaces and jogs across the atomic layer between the two adjacent interfaces.more » Finally, under biaxial tension/compression applied parallel to the interface, we show that the nucleation of lattice dislocations is preferred at the nodes and is correlated with the reduction of excess volume at the nodes.« less

  8. "Conjugate channeling" effect in dislocation core diffusion: carbon transport in dislocated BCC iron.

    PubMed

    Ishii, Akio; Li, Ju; Ogata, Shigenobu

    2013-01-01

    Dislocation pipe diffusion seems to be a well-established phenomenon. Here we demonstrate an unexpected effect, that the migration of interstitials such as carbon in iron may be accelerated not in the dislocation line direction ξ, but in a conjugate diffusion direction. This accelerated random walk arises from a simple crystallographic channeling effect. c is a function of the Burgers vector b, but not ξ, thus a dislocation loop possesses the same everywhere. Using molecular dynamics and accelerated dynamics simulations, we further show that such dislocation-core-coupled carbon diffusion in iron has temperature-dependent activation enthalpy like a fragile glass. The 71° mixed dislocation is the only case in which we see straightforward pipe diffusion that does not depend on dislocation mobility.

  9. Debye screening of dislocations.

    PubMed

    Groma, I; Györgyi, G; Kocsis, B

    2006-04-28

    Debye-like screening by edge dislocations of some externally given stress is studied by means of a variational approach to coarse grained field theory. Explicitly given are the force field and the induced geometrically necessary dislocation (GND) distribution, in the special case of a single glide axis in 2D, for (i) a single edge dislocation and (ii) a dislocation wall. Numerical simulation demonstrates that the correlation in relaxed dislocation configurations is in good agreement with the induced GND in case (i). Furthermore, the result (ii) well predicts the experimentally observed decay length for the GND developing close to grain boundaries.

  10. Tailoring Superconductivity with Quantum Dislocations.

    PubMed

    Li, Mingda; Song, Qichen; Liu, Te-Huan; Meroueh, Laureen; Mahan, Gerald D; Dresselhaus, Mildred S; Chen, Gang

    2017-08-09

    Despite the established knowledge that crystal dislocations can affect a material's superconducting properties, the exact mechanism of the electron-dislocation interaction in a dislocated superconductor has long been missing. Being a type of defect, dislocations are expected to decrease a material's superconducting transition temperature (T c ) by breaking the coherence. Yet experimentally, even in isotropic type I superconductors, dislocations can either decrease, increase, or have little influence on T c . These experimental findings have yet to be understood. Although the anisotropic pairing in dirty superconductors has explained impurity-induced T c reduction, no quantitative agreement has been reached in the case a dislocation given its complexity. In this study, by generalizing the one-dimensional quantized dislocation field to three dimensions, we reveal that there are indeed two distinct types of electron-dislocation interactions. Besides the usual electron-dislocation potential scattering, there is another interaction driving an effective attraction between electrons that is caused by dislons, which are quantized modes of a dislocation. The role of dislocations to superconductivity is thus clarified as the competition between the classical and quantum effects, showing excellent agreement with existing experimental data. In particular, the existence of both classical and quantum effects provides a plausible explanation for the illusive origin of dislocation-induced superconductivity in semiconducting PbS/PbTe superlattice nanostructures. A quantitative criterion has been derived, in which a dislocated superconductor with low elastic moduli and small electron effective mass and in a confined environment is inclined to enhance T c . This provides a new pathway for engineering a material's superconducting properties by using dislocations as an additional degree of freedom.

  11. Immobilization in Neutral Rotation for a Glenohumeral Dislocation Using a Sling and Splint

    PubMed Central

    2008-01-01

    The purpose of this manuscript is to provide an expedient means of immobilizing a glenohumeral dislocation in neutral rotation. This technique for post-reduction immobilization of a glenohumeral dislocation is inexpensive and easy to fabricate. Anterior glenohumeral dislocations often involve an avulsion of the labrum from the glenoid rim. In contrast to immobilization in internal rotation, positioning the shoulder in 0-45° of external rotation approximates the labrum and glenoid rim. It is hypothesized that placing the shoulder in a more externally rotated position could allow for better healing and increased joint stability. This technique places the shoulder in neutral rotation, because 45° of external rotation is awkward and may interfere with certain activities of daily living. Structural aluminum malleable (SAM) splints are used as an alternative to a bolster sling. The SAM splints are lightweight, simply shaped, and easily stored. PMID:21509136

  12. Statistical analysis of dislocations and dislocation boundaries from EBSD data.

    PubMed

    Moussa, C; Bernacki, M; Besnard, R; Bozzolo, N

    2017-08-01

    Electron BackScatter Diffraction (EBSD) is often used for semi-quantitative analysis of dislocations in metals. In general, disorientation is used to assess Geometrically Necessary Dislocations (GNDs) densities. In the present paper, we demonstrate that the use of disorientation can lead to inaccurate results. For example, using the disorientation leads to different GND density in recrystallized grains which cannot be physically justified. The use of disorientation gradients allows accounting for measurement noise and leads to more accurate results. Misorientation gradient is then used to analyze dislocations boundaries following the same principle applied on TEM data before. In previous papers, dislocations boundaries were defined as Geometrically Necessary Boundaries (GNBs) and Incidental Dislocation Boundaries (IDBs). It has been demonstrated in the past, through transmission electron microscopy data, that the probability density distribution of the disorientation of IDBs and GNBs can be described with a linear combination of two Rayleigh functions. Such function can also describe the probability density of disorientation gradient obtained through EBSD data as reported in this paper. This opens the route for determining IDBs and GNBs probability density distribution functions separately from EBSD data, with an increased statistical relevance as compared to TEM data. The method is applied on deformed Tantalum where grains exhibit dislocation boundaries, as observed using electron channeling contrast imaging. Copyright © 2017 Elsevier B.V. All rights reserved.

  13. Supersonic Dislocation Bursts in Silicon

    DOE PAGES

    Hahn, E. N.; Zhao, S.; Bringa, E. M.; ...

    2016-06-06

    Dislocations are the primary agents of permanent deformation in crystalline solids. Since the theoretical prediction of supersonic dislocations over half a century ago, there is a dearth of experimental evidence supporting their existence. Here we use non-equilibrium molecular dynamics simulations of shocked silicon to reveal transient supersonic partial dislocation motion at approximately 15 km/s, faster than any previous in-silico observation. Homogeneous dislocation nucleation occurs near the shock front and supersonic dislocation motion lasts just fractions of picoseconds before the dislocations catch the shock front and decelerate back to the elastic wave speed. Applying a modified analytical equation for dislocation evolutionmore » we successfully predict a dislocation density of 1.5 x 10(12) cm(-2) within the shocked volume, in agreement with the present simulations and realistic in regards to prior and on-going recovery experiments in silicon.« less

  14. Supersonic Dislocation Bursts in Silicon

    PubMed Central

    Hahn, E. N.; Zhao, S.; Bringa, E. M.; Meyers, M. A.

    2016-01-01

    Dislocations are the primary agents of permanent deformation in crystalline solids. Since the theoretical prediction of supersonic dislocations over half a century ago, there is a dearth of experimental evidence supporting their existence. Here we use non-equilibrium molecular dynamics simulations of shocked silicon to reveal transient supersonic partial dislocation motion at approximately 15 km/s, faster than any previous in-silico observation. Homogeneous dislocation nucleation occurs near the shock front and supersonic dislocation motion lasts just fractions of picoseconds before the dislocations catch the shock front and decelerate back to the elastic wave speed. Applying a modified analytical equation for dislocation evolution we successfully predict a dislocation density of 1.5 × 1012 cm−2 within the shocked volume, in agreement with the present simulations and realistic in regards to prior and on-going recovery experiments in silicon. PMID:27264746

  15. Supersonic Dislocation Bursts in Silicon

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Hahn, E. N.; Zhao, S.; Bringa, E. M.

    Dislocations are the primary agents of permanent deformation in crystalline solids. Since the theoretical prediction of supersonic dislocations over half a century ago, there is a dearth of experimental evidence supporting their existence. Here we use non-equilibrium molecular dynamics simulations of shocked silicon to reveal transient supersonic partial dislocation motion at approximately 15 km/s, faster than any previous in-silico observation. Homogeneous dislocation nucleation occurs near the shock front and supersonic dislocation motion lasts just fractions of picoseconds before the dislocations catch the shock front and decelerate back to the elastic wave speed. Applying a modified analytical equation for dislocation evolutionmore » we successfully predict a dislocation density of 1.5 x 10(12) cm(-2) within the shocked volume, in agreement with the present simulations and realistic in regards to prior and on-going recovery experiments in silicon.« less

  16. Dislocation dynamics simulations of interactions between gliding dislocations and radiation induced prismatic loops in zirconium

    NASA Astrophysics Data System (ADS)

    Drouet, Julie; Dupuy, Laurent; Onimus, Fabien; Mompiou, Frédéric; Perusin, Simon; Ambard, Antoine

    2014-06-01

    The mechanical behavior of Pressurized Water Reactor fuel cladding tubes made of zirconium alloys is strongly affected by neutron irradiation due to the high density of radiation induced dislocation loops. In order to investigate the interaction mechanisms between gliding dislocations and loops in zirconium, a new nodal dislocation dynamics code, adapted to Hexagonal Close Packed metals, has been used. Various configurations have been systematically computed considering different glide planes, basal or prismatic, and different characters, edge or screw, for gliding dislocations with -type Burgers vectors. Simulations show various interaction mechanisms such as (i) absorption of a loop on an edge dislocation leading to the formation of a double super-jog, (ii) creation of a helical turn, on a screw dislocation, that acts as a strong pinning point or (iii) sweeping of a loop by a gliding dislocation. It is shown that the clearing of loops is more favorable when the dislocation glides in the basal plane than in the prismatic plane explaining the easy dislocation channeling in the basal plane observed after neutron irradiation by transmission electron microscopy.

  17. Autologous blood injection for treatment of chronic recurrent TMJ dislocation: is it successful? Is it safe enough? A systematic review.

    PubMed

    Varedi, Payam; Bohluli, Behnam

    2015-09-01

    The purpose of this article is to review the English literature about the efficacy and safety of autologous blood injection in treating patients suffering from chronic recurrent temporomandibular joint dislocation. In this article, we highlight the key trials and recent directions about this modality and discuss about the mechanism, advantages, and disadvantages of this approach. A literature search was performed using PubMed, Medline, and Ovid Medline databases to identify articles reporting on the injection of autologous blood for treatment of chronic recurrent dislocation of temporomandibular joint. Other references cited in the retrieved reports, as well as the "related articles" tool in PubMed Medline, were also checked to improve the search and, if relevant, were included in the study. The search was restricted to articles published in the English language. Seven studies meeting the inclusion criteria were reviewed. The selected articles included four prospective clinical trials and three case report articles. There are a few articles about the clinical use of autologous blood for treating patients with chronic recurrent temporomandibular joint dislocation. Reviewing of the literature shows that there are successful results about this modality, but there are still some concerns about it in terms of the effect of the injected blood on the articular cartilage and formation of fibrous or bony ankylosis.

  18. Six-week physical rehabilitation protocol for anterior shoulder dislocation in athletes

    PubMed Central

    Gaballah, Ahmed; Zeyada, Mohamed; Elgeidi, Adham; Bressel, Eadric

    2017-01-01

    Anterior shoulder dislocations are common in young athletes. The mechanism for the first or primary shoulder dislocation may involve a collision or a fall typically with the arm in an abducted and externally rotated position. The aim of this study was to design a physical rehabilitation program using the elastic band and resistive exercise to improve joint strength and range of motion in individuals diagnosed with a first-time shoulder dislocation. Twelve physically active males with a first-time acute shoulder dislocation were asked to volunteer. Participants began a physical rehabilitation program 2 weeks after the shoulder dislocation, which was confirmed by a referring physician. The rehabilitation program was 6 weeks in duration and required the participants to engage in progressive resistive loads/duration using elastic bands and weights 5 days per week. Pretest and posttest measures included shoulder strength and range of motion. All outcome measures were compared between the injured and uninjured shoulder, which served as the control condition in this study. There were statistically significant differences between the injured and uninjured shoulder for measures of strength and range of motion during pretests (P<0.01) but not post-tests (P<0.53). Finally, there were no differences between shoulders in regards to the volume measure suggesting that any changes in muscle atrophy or swelling were not detected. The physical rehabilitation program proposed in this study was effective at improving strength and range of motion in the injured shoulder as evidenced by the similarity in posttest values between the injured and uninjured shoulder. PMID:28702449

  19. A continuum theory of edge dislocations

    NASA Astrophysics Data System (ADS)

    Berdichevsky, V. L.

    2017-09-01

    Continuum theory of dislocation aims to describe the behavior of large ensembles of dislocations. This task is far from completion, and, most likely, does not have a "universal solution", which is applicable to any dislocation ensemble. In this regards it is important to have guiding lines set by benchmark cases, where the transition from a discrete set of dislocations to a continuum description is made rigorously. Two such cases have been considered recently: equilibrium of dislocation walls and screw dislocations in beams. In this paper one more case is studied, equilibrium of a large set of 2D edge dislocations placed randomly in a 2D bounded region. The major characteristic of interest is energy of dislocation ensemble, because it determines the structure of continuum equations. The homogenized energy functional is obtained for the periodic dislocation ensembles with a random contents of the periodic cell. Parameters of the periodic structure can change slowly on distances of order of the size of periodic cells. The energy functional is obtained by the variational-asymptotic method. Equilibrium positions are local minima of energy. It is confirmed the earlier assertion that energy density of the system is the sum of elastic energy of averaged elastic strains and microstructure energy, which is elastic energy of the neutralized dislocation system, i.e. the dislocation system placed in a constant dislocation density field making the averaged dislocation density zero. The computation of energy is reduced to solution of a variational cell problem. This problem is solved analytically. The solution is used to investigate stability of simple dislocation arrays, i.e. arrays with one dislocation in the periodic cell. The relations obtained yield two outcomes: First, there is a state parameter of the system, dislocation polarization; averaged stresses affect only dislocation polarization and cannot change other characteristics of the system. Second, the structure of

  20. Knee Dislocations

    PubMed Central

    Schenck, Robert C.; Richter, Dustin L.; Wascher, Daniel C.

    2014-01-01

    Background: Traumatic knee dislocation is becoming more prevalent because of improved recognition and increased exposure to high-energy trauma, but long-term results are lacking. Purpose: To present 2 cases with minimum 20-year follow-up and a review of the literature to illustrate some of the fundamental principles in the management of the dislocated knee. Study Design: Review and case reports. Methods: Two patients with knee dislocations who underwent multiligamentous knee reconstruction were reviewed, with a minimum 20-year follow-up. These patients were brought back for a clinical evaluation using both subjective and objective measures. Subjective measures include the following scales: Lysholm, Tegner activity, visual analog scale (VAS), Short Form–36 (SF-36), International Knee Documentation Committee (IKDC), and a psychosocial questionnaire. Objective measures included ligamentous examination, radiographic evaluation (including Telos stress radiographs), and physical therapy assessment of function and stability. Results: The mean follow-up was 22 years. One patient had a vascular injury requiring repair prior to ligament reconstruction. The average assessment scores were as follows: SF-36 physical health, 52; SF-36 mental health, 59; Lysholm, 92; IKDC, 86.5; VAS involved, 10.5 mm; and VAS uninvolved, 2.5 mm. Both patients had excellent stability and were functioning at high levels of activity for their age (eg, hiking, skydiving). Both patients had radiographic signs of arthritis, which lowered 1 subject’s IKDC score to “C.” Conclusion: Knee dislocations have rare long-term excellent results, and most intermediate-term studies show fair to good functional results. By following fundamental principles in the management of a dislocated knee, patients can be given the opportunity to function at high levels. Hopefully, continued advances in the evaluation and treatment of knee dislocations will improve the long-term outcomes for these patients in the

  1. “Conjugate Channeling” Effect in Dislocation Core Diffusion: Carbon Transport in Dislocated BCC Iron

    PubMed Central

    Ishii, Akio; Li, Ju; Ogata, Shigenobu

    2013-01-01

    Dislocation pipe diffusion seems to be a well-established phenomenon. Here we demonstrate an unexpected effect, that the migration of interstitials such as carbon in iron may be accelerated not in the dislocation line direction , but in a conjugate diffusion direction. This accelerated random walk arises from a simple crystallographic channeling effect. is a function of the Burgers vector b, but not , thus a dislocation loop possesses the same everywhere. Using molecular dynamics and accelerated dynamics simulations, we further show that such dislocation-core-coupled carbon diffusion in iron has temperature-dependent activation enthalpy like a fragile glass. The 71° mixed dislocation is the only case in which we see straightforward pipe diffusion that does not depend on dislocation mobility. PMID:23593255

  2. Utilization of the Safe Surgical Dislocation Approach of the Hip to Retrieve a Bullet from the Femoral Head

    PubMed Central

    Delaney, Ruth; Albright, Maurice; Rebello, Gleeson

    2011-01-01

    Retained intra-articular missiles from low-velocity handguns can lead to mechanical arthritis, synovitis, and lead toxicity. Various surgical approaches have been described to extract such foreign bodies from the hip joint. We present the case of a 17-year-old male in which the surgical dislocation approach was utilized to retrieve a bullet from the femoral head with a good short-term outcome. This case represents a rare application of the surgical hip dislocation approach for an unusual trauma. PMID:23198205

  3. [Study on the effect of vertebrae semi-dislocation on the stress distribution in facet joint and interuertebral disc of patients with cervical syndrome based on the three dimensional finite element model].

    PubMed

    Zhang, Ming-cai; Lü, Si-zhe; Cheng, Ying-wu; Gu, Li-xu; Zhan, Hong-sheng; Shi, Yin-yu; Wang, Xiang; Huang, Shi-rong

    2011-02-01

    To study the effect of vertebrae semi-dislocation on the stress distribution in facet joint and interuertebral disc of patients with cervical syndrome using three dimensional finite element model. A patient with cervical spondylosis was randomly chosen, who was male, 28 years old, and diagnosed as cervical vertebra semidislocation by dynamic and static palpation and X-ray, and scanned from C(1) to C(7) by 0.75 mm slice thickness of CT. Based on the CT data, the software was used to construct the three dimensional finite element model of cervical vertebra semidislocation (C(4)-C(6)). Based on the model,virtual manipulation was used to correct the vertebra semidislocation by the software, and the stress distribution was analyzed. The result of finite element analysis showed that the stress distribution of C(5-6) facet joint and intervertebral disc changed after virtual manipulation. The vertebra semidislocation leads to the abnormal stress distribution of facet joint and intervertebral disc.

  4. Quantifying the effect of hydrogen on dislocation dynamics: A three-dimensional discrete dislocation dynamics framework

    NASA Astrophysics Data System (ADS)

    Gu, Yejun; El-Awady, Jaafar A.

    2018-03-01

    We present a new framework to quantify the effect of hydrogen on dislocations using large scale three-dimensional (3D) discrete dislocation dynamics (DDD) simulations. In this model, the first order elastic interaction energy associated with the hydrogen-induced volume change is accounted for. The three-dimensional stress tensor induced by hydrogen concentration, which is in equilibrium with respect to the dislocation stress field, is derived using the Eshelby inclusion model, while the hydrogen bulk diffusion is treated as a continuum process. This newly developed framework is utilized to quantify the effect of different hydrogen concentrations on the dynamics of a glide dislocation in the absence of an applied stress field as well as on the spacing between dislocations in an array of parallel edge dislocations. A shielding effect is observed for materials having a large hydrogen diffusion coefficient, with the shield effect leading to the homogenization of the shrinkage process leading to the glide loop maintaining its circular shape, as well as resulting in a decrease in dislocation separation distances in the array of parallel edge dislocations. On the other hand, for materials having a small hydrogen diffusion coefficient, the high hydrogen concentrations around the edge characters of the dislocations act to pin them. Higher stresses are required to be able to unpin the dislocations from the hydrogen clouds surrounding them. Finally, this new framework can open the door for further large scale studies on the effect of hydrogen on the different aspects of dislocation-mediated plasticity in metals. With minor modifications of the current formulations, the framework can also be extended to account for general inclusion-induced stress field in discrete dislocation dynamics simulations.

  5. Treatment of chronic mandibular dislocations by eminectomy: follow-up of 10 cases and literature review.

    PubMed

    Vasconcelos, Belmiro-Cavalcanti do Egito; Porto, Gabriela-Granja; Neto, José-Pacheco-Martins-Ribeiro; Vasconcelos, César-Freire de Melo

    2009-11-01

    Temporomandibular joint (TMJ) dislocation is defined as an excessive forward movement of the condyle beyond the articular eminence, with complete separation of the articular surfaces and fixation in that position. To report ten cases treated by eminectomy for chronic mandibular dislocations, to evaluate the results of these surgeries and make a critical review of the literature. The sample was obtained from the records of the Department of Oral and Maxillofacial Surgery, University of Pernambuco and comprises cases submitted to chronic mandibular dislocation treatment by eminectomy between 2002 and 2007. Pre- and postoperative assessment included a thorough history and physical examination to determine the maximal mouth opening, presence of pain and sounds, frequency of luxations, recurrence rate and presence of facial nerve paralysis. The mean maximal mouth opening in the preoperative period was 48.4 +/- 8.5 mm and in the postoperative period it was 41.3 +/- 5.0 mm. No facial nerve paralysis or recurrence was observed. The treatment of chronic mandibular dislocations by eminectomy was shown to be efficient in relationship to the postoperative maximal mouth opening, recurrence and articular function.

  6. Habitual dislocation of patella: A review

    PubMed Central

    Batra, Sumit; Arora, Sumit

    2014-01-01

    Habitual dislocation of patella is a condition where the patella dislocates whenever the knee is flexed and spontaneously relocates with extension of the knee. It is also termed as obligatory dislocation as the patella dislocates completely with each flexion and extension cycle of the knee and the patient has no control over the patella dislocating as he or she moves the knee1. It usually presents after the child starts to walk, and is often well tolerated in children, if it is not painful. However it may present in childhood with dysfunction and instability. Very little literature is available on habitual dislocation of patella as most of the studies have combined cases of recurrent dislocation with habitual dislocation. Many different surgical techniques have been described in the literature for the treatment of habitual dislocation of patella. No single procedure is fully effective in the surgical treatment of habitual dislocation of patella and a combination of procedures is recommended. PMID:25983506

  7. Acromioclavicular Joint Fixation Using an Acroplate Combined With a Coracoclavicular Screw

    PubMed Central

    Tavakoli Darestani, Reza; Ghaffari, Arash; Hosseinpour, Mehrdad

    2013-01-01

    Background Appropriate treatment of acromioclavicular joint dislocation is controversial. Acroplate fixation is one of the most common treatment methods of acromioclavicular joint (ACJ) dislocation. Based on the risk of re-dislocation after Acroplate fixation, we assumed that combined fixation with an Acroplate and a coracoclavicular screw helps improve the outcome. Objectives The main purpose of the current study was to compare the outcome of ACJ dislocation treated with an Acroplate alone and in combination with coracoclavicular screw. Patients and Methods This study was carried out on 40 patients with ACJ dislocation types III to VI who were divided randomly into two equal groups: Acroplate group (P) and Acroplate in combination with coracoclavicular screw group (P + S). The screws were extracted 3-6 months postoperatively. The patients were followed for 1 year and Imatani’s score was calculated. Finally, the data were compared between the groups. Results The mean Imatani’s score was significantly higher in P + S group (83.4 ± 14.1) than P group (81.2 ± 10.3) (P < 0.001). The mean duration of surgery was the same in the two groups (59.8 ± 9.4 minutes in group P V.s 64.3 ± 10.9 minutes in group P + S; P = 0.169). There were no cases of re-dislocation, degenerative changes and ossification and all patients returned to their previous jobs or sporting activities. Conclusions Using a coracoclavicular screw combined with an Acroplate can improve the patients’ function after ACJ disruption without any significant increase in surgical duration. Authors recommend this technique in the fixation of ACJ dislocation. PMID:24396788

  8. Using O*NET in Dislocated Worker Retraining: The Toledo Dislocated Worker Consortium Project.

    ERIC Educational Resources Information Center

    Sommers, Dixie; Austin, James

    A project used the Occupational Information Network (O*NET) to assist eligible dislocated workers in determining whether training offered by the Toledo Dislocated Worker Consortium fit their needs. More specifically, O*NET was used to help the dislocated workers understand whether they had knowledge and skills that were transferable into the…

  9. Geared Electromechanical Rotary Joint

    NASA Technical Reports Server (NTRS)

    Vranish, John M.

    1994-01-01

    Geared rotary joint provides low-noise ac or dc electrical contact between electrical subsystems rotating relative to each other. Designed to overcome some disadvantages of older electromechanical interfaces, especially intermittency of sliding-contact and rolling-contact electromechanical joints. Hollow, springy planetary gears provide continuous, redundant, low-noise electrical contact between inner and outer gears.

  10. Three-dimensional formulation of dislocation climb

    NASA Astrophysics Data System (ADS)

    Gu, Yejun; Xiang, Yang; Quek, Siu Sin; Srolovitz, David J.

    2015-10-01

    We derive a Green's function formulation for the climb of curved dislocations and multiple dislocations in three-dimensions. In this new dislocation climb formulation, the dislocation climb velocity is determined from the Peach-Koehler force on dislocations through vacancy diffusion in a non-local manner. The long-range contribution to the dislocation climb velocity is associated with vacancy diffusion rather than from the climb component of the well-known, long-range elastic effects captured in the Peach-Koehler force. Both long-range effects are important in determining the climb velocity of dislocations. Analytical and numerical examples show that the widely used local climb formula, based on straight infinite dislocations, is not generally applicable, except for a small set of special cases. We also present a numerical discretization method of this Green's function formulation appropriate for implementation in discrete dislocation dynamics (DDD) simulations. In DDD implementations, the long-range Peach-Koehler force is calculated as is commonly done, then a linear system is solved for the climb velocity using these forces. This is also done within the same order of computational cost as existing discrete dislocation dynamics methods.

  11. Comparison of four different reduction methods for anterior dislocation of the shoulder.

    PubMed

    Guler, Olcay; Ekinci, Safak; Akyildiz, Faruk; Tirmik, Uzeyir; Cakmak, Selami; Ugras, Akin; Piskin, Ahmet; Mahirogullari, Mahir

    2015-05-28

    Shoulder dislocations account for almost 50% of all major joint dislocations and are mainly anterior. The aim is a comparative retrospective study of different reduction maneuvers without anesthesia to reduce the dislocated shoulder. Patients were treated with different reduction maneuvers, including various forms of traction and external rotation, in the emergency departments of four training hospitals between 2009 and 2012. Each of the four hospitals had different treatment protocols for reduction and applying one of four maneuvers: Spaso, Chair, Kocher, and Matsen methods. Thirty-nine patients were treated by the Spaso method, 47 by the Chair reduction method, 40 by the Kocher method, and 27 patients by Matsen's traction-countertraction method. All patients' demographic data were recorded. Dislocation number, reduction time, time interval between dislocation and reduction, and associated complications, pre- and post-reduction period, were recorded prospectively. No anesthetic method was used for the reduction. All of the methods used included traction and some external rotation. The Chair method had the shortest reduction time. All surgeons involved in the study agreed that the Kocher and Matsen methods needed more force for the reduction. Patients could contract their muscles because of the pain in these two methods. The Spaso method includes flexion of the shoulder and blocks muscle contraction somewhat. The Chair method was found to be the easiest because the patients could not contract their muscles while sitting on a chair with the affected arm at their side. We suggest that the Chair method is an effective and fast reduction maneuver that may be an alternative for the treatment of anterior shoulder dislocations. Further prospective studies with larger sample size are needed to compare safety of different reduction techniques.

  12. The effect of isolated dislocations on substrate and device properties in low-dislocation czochralski GaAs

    NASA Astrophysics Data System (ADS)

    Hunter, A. T.; Kimura, H.; Olsen, H. M.; Winston, H. V.

    1986-07-01

    Czochralski GaAs grown with In incorporated into the melt has large regions with fewer than 100 cm-2 dislocations. We have examined the effect of these dislocations on substrate and device properties. Infrared transmission images reveal dark filaments of high EL2 concentration a few tens of microns in diameter surrounding dislocations, Cathodo and photoluminescence images show orders of magnitude contrast in band-edge luminescence intensity near dislocations. Single dislocations appear to be surrounded by bright rings ˜200 μm in diameter in luminescence images, with dark spots 50 to 75 μm across centered on the dislocation. More complex luminescence structures with larger dark regions (˜150 μ across) and central bright spots are centered on small dislocation clusters. Differences in lifetime of photogenerated electrons or holes are the most likely cause of the luminescence contrast. Anneals typical of our post-implant processing substantially lower the luminescence contrast, suggesting the defect lowering the lifetime is removed by annealing. This may partially explain why we do not observe any effect of dislocation proximity on the properties of devices made in the material, in spite of the enormous luminescence contrast observed near dislocations.

  13. A concise evidence-based physical examination for diagnosis of acromioclavicular joint pathology: a systematic review.

    PubMed

    Krill, Michael K; Rosas, Samuel; Kwon, KiHyun; Dakkak, Andrew; Nwachukwu, Benedict U; McCormick, Frank

    2018-02-01

    The clinical examination of the shoulder joint is an undervalued diagnostic tool for evaluating acromioclavicular (AC) joint pathology. Applying evidence-based clinical tests enables providers to make an accurate diagnosis and minimize costly imaging procedures and potential delays in care. The purpose of this study was to create a decision tree analysis enabling simple and accurate diagnosis of AC joint pathology. A systematic review of the Medline, Ovid and Cochrane Review databases was performed to identify level one and two diagnostic studies evaluating clinical tests for AC joint pathology. Individual test characteristics were combined in series and in parallel to improve sensitivities and specificities. A secondary analysis utilized subjective pre-test probabilities to create a clinical decision tree algorithm with post-test probabilities. The optimal special test combination to screen and confirm AC joint pathology combined Paxinos sign and O'Brien's Test, with a specificity of 95.8% when performed in series; whereas, Paxinos sign and Hawkins-Kennedy Test demonstrated a sensitivity of 93.7% when performed in parallel. Paxinos sign and O'Brien's Test demonstrated the greatest positive likelihood ratio (2.71); whereas, Paxinos sign and Hawkins-Kennedy Test reported the lowest negative likelihood ratio (0.35). No combination of special tests performed in series or in parallel creates more than a small impact on post-test probabilities to screen or confirm AC joint pathology. Paxinos sign and O'Brien's Test is the only special test combination that has a small and sometimes important impact when used both in series and in parallel. Physical examination testing is not beneficial for diagnosis of AC joint pathology when pretest probability is unequivocal. In these instances, it is of benefit to proceed with procedural tests to evaluate AC joint pathology. Ultrasound-guided corticosteroid injections are diagnostic and therapeutic. An ultrasound-guided AC joint

  14. Dislocations in bilayer graphene

    NASA Astrophysics Data System (ADS)

    Butz, Benjamin; Dolle, Christian; Niekiel, Florian; Weber, Konstantin; Waldmann, Daniel; Weber, Heiko B.; Meyer, Bernd; Spiecker, Erdmann

    2014-01-01

    Dislocations represent one of the most fascinating and fundamental concepts in materials science. Most importantly, dislocations are the main carriers of plastic deformation in crystalline materials. Furthermore, they can strongly affect the local electronic and optical properties of semiconductors and ionic crystals. In materials with small dimensions, they experience extensive image forces, which attract them to the surface to release strain energy. However, in layered crystals such as graphite, dislocation movement is mainly restricted to the basal plane. Thus, the dislocations cannot escape, enabling their confinement in crystals as thin as only two monolayers. To explore the nature of dislocations under such extreme boundary conditions, the material of choice is bilayer graphene, the thinnest possible quasi-two-dimensional crystal in which such linear defects can be confined. Homogeneous and robust graphene membranes derived from high-quality epitaxial graphene on silicon carbide provide an ideal platform for their investigation. Here we report the direct observation of basal-plane dislocations in freestanding bilayer graphene using transmission electron microscopy and their detailed investigation by diffraction contrast analysis and atomistic simulations. Our investigation reveals two striking size effects. First, the absence of stacking-fault energy, a unique property of bilayer graphene, leads to a characteristic dislocation pattern that corresponds to an alternating ABAC change of the stacking order. Second, our experiments in combination with atomistic simulations reveal a pronounced buckling of the bilayer graphene membrane that results directly from accommodation of strain. In fact, the buckling changes the strain state of the bilayer graphene and is of key importance for its electronic properties. Our findings will contribute to the understanding of dislocations and of their role in the structural, mechanical and electronic properties of bilayer and

  15. [Outcomes and complications of Tightrope button plate for repairing acromioclavicular dislocation].

    PubMed

    Zuo, Yong-Xiang; Ma, Zi-Ping

    2017-10-25

    To study the clinical outcome and complications of Tightrope button plate for repairing acromioclavicular dislocation of Rockwood type III to V. From May 2014 to December 2016, 17 patients with acromioclavicular dislocation of type III-V were treated with Tightrope button plate including 10 males and 7 females with an average age 39.8 years old ranging from 20 to 68 years old. Four patients were treated with arthroscopy and 17 patients were treated with mini-invasive by X-ray assisted. Shoulder function, X-ray and complications after operation were assessed. All patients were followed up for 5 to 23 months with a mean of 10.8 months. All patients got satisfying reduction immediately postoperatively. Among them, 1 case of clavicle end wound foreign body reaction, rupture, effusion, healing after the second suture; 1 case of foreign body granuloma formation at the end of clavicle were resected and removed at 4 months after operation; 3 cases loss reduction(less than 50% of acromioclavicular joint). No coracoid fracture and suture breakage observed. The shoulder mobility was restored in 15 cases at 4 to 6 weeks postoperatively, and the shoulder adhesion in 2 cases was delayed to 5 to 7 months after operation. The Constant scores were improved from 46.9±6.0 preoperatively to 92.7±4.0 at the final follow-up. X-ray evaluation of postoperative coracoclavicular tunnel location, patients' coracoclavicular tunnel with mini-invasive fluoroscopy all closed to the ideal position (across the clavicle vertically through the coracoid base center), while different degree of tunnel position deviation were observed in arthroscopic patients. Tightrope button plate for the treatment of acromioclavicular joint dislocation had advantages of minimally invasive, effective, good clinical results, the majority of common complications does not affect efficacy. Small incision X-ray method can provide more satisfactory and reliable tunnel location.

  16. Effects of dislocations on polycrystal anelasticity

    NASA Astrophysics Data System (ADS)

    Sasaki, Y.; Takei, Y.; McCarthy, C.; Suzuki, A.

    2017-12-01

    Effects of dislocations on the seismic velocity and attenuation have been poorly understood, because only a few experimental studies have been performed [Guéguen et al., 1989; Farla et al., 2012]. By using organic borneol as a rock analogue, we measured dislocation-induced anelasticity accurately over a broad frequency range. We first measured the flow law of borneol aggregates by uniaxial compression tests under a confining pressure of 0.8 MPa. A transition from diffusion creep (n = 1) to dislocation creep (n = 5) was captured at about σ = 1 MPa (40°C-50°C). After deforming in the dislocation creep regime, sample microstructure showed irregular grain shape consistent with grain boundary migration. Next, we conducted three creep tests at σ = 0.27 MPa (diffusion creep regime), σ = 1.3 MPa and σ = 1.9 MPa (dislocation creep regime) on the same sample in increasing order, and measured Young's modulus E and attenuation Q-1 after each creep test by forced oscillation tests. The results show that as σ increased, E decreased and Q-1 increased. These changes induced by dislocations, however, almost fully recovered during the forced oscillation tests performed for about two weeks under a small stress (σ = 0.27 MPa) due to the dislocation recovery (annihilation). In order to constrain the time scale of the dislocation-induced anelastic relaxation, we further measured Young's modulus E at ultrasonic frequency before and after the dislocation creep and found that E at 106 Hz is not influenced by dislocations. Because E at 100 Hz is reduced by dislocations by 10%, the dislocation-induced anelastic relaxation occurs mostly between 102-106 Hz which is at a higher frequency than grain-boundary-induced anelasticity. To avoid dislocation recovery during the anelasticity measurement, we are now trying to perform an in-situ measurement of anelasticity while simultaneously deforming under a high stress associated with dislocation creep. The combination of persistent creep

  17. Anatomical principles for minimally invasive reconstruction of the acromioclavicular joint with anchors.

    PubMed

    Xiong, Chuanzhi; Lu, Yaojia; Wang, Qiang; Chen, Gang; Hu, Hansheng; Lu, Zhihua

    2016-11-01

    The aim of this study was to evaluate the outcome of a minimally invasive surgical technique for the treatment of patients with acromioclavicular joint dislocation. Sixteen patients with complete acromioclavicular joint dislocation were enrolled in this study. All patients were asked to follow the less active rehabilitation protocol post-operatively. Computed tomography with 3-D reconstruction of the injured shoulder was performed on each patient post operatively for the assessment of the accuracy of the suture anchor placement in the coracoid process and the reduction of the acromioclavicular joint. Radiographs of Zanca view and axillary view of both shoulders were taken for evaluating the maintenance of the acromioclavicular joint reduction at each follow-up visit. The Constant shoulder score was used for function assessment at the final follow-up. Twenty seven of the 32 anchors implanted in the coracoid process met the criteria of good position. One patient developed complete loss of reduction and another had partial loss of reduction in the anteroposterior plane. For the other 14 patients, the mean Constant score was 90 (range, 82-95). For the patients with partial and complete loss of reduction, the Constant score were 92 and 76 respectively. All of them got nearly normal range of motion of the shoulders and restored to pre-operative life and works. With this minimally invasive approach and limited exposure of the coracoid, a surgeon can place the suture anchors at the anatomical insertions of the coracoclavicular ligament and allow the dislocated joint reduced and maintained well. Level IV, Case series; therapeutic study.

  18. Biomechanical analysis of the influence of friction in jaw joint disorders.

    PubMed

    Koolstra, J H

    2012-01-01

    Increased friction due to impaired lubrication in the jaw joint has been considered as one of the possible causes for internal joint disorders. A very common internal disorder in the jaw joint is an anteriorly dislocated articular disc. This is generally considered to contribute to the onset of arthritic injuries. Increase of friction as caused by impairment of lubrication is suspected to be a possible cause for such a disorder. The influence of friction was addressed by analysis of its effects on tensions and deformations of the cartilaginous structures in the jaw joint using computational biomechanical analysis. Jaw open-close movements were simulated while in one or two compartments of the right joint friction was applied in the articular contact. The left joint was treated as the healthy control. The simulations predicted that friction primarily causes increased shear stress in the articular cartilage layers, but hardly in the articular disc. This suggests that impaired lubrication may facilitate deterioration of the cartilage-subchondral bone unit of the articular surfaces. The results further suggest that increased friction is not a plausible cause for turning a normally functioning articular disc into an anteriorly dislocated one. Copyright © 2011 Osteoarthritis Research Society International. Published by Elsevier Ltd. All rights reserved.

  19. Recombination properties of dislocations in GaN

    NASA Astrophysics Data System (ADS)

    Yakimov, Eugene B.; Polyakov, Alexander Y.; Lee, In-Hwan; Pearton, Stephen J.

    2018-04-01

    The recombination activity of threading dislocations in n-GaN with different dislocation densities and different doping levels was studied using electron beam induced current (EBIC). The recombination velocity on a dislocation, also known as the dislocation recombination strength, was calculated. The results suggest that dislocations in n-GaN giving contrast in EBIC are charged and surrounded by a space charge region, as evidenced by the observed dependence of dislocation recombination strength on dopant concentration. For moderate (below ˜108 cm-2) dislocation densities, these defects do not primarily determine the average diffusion length of nonequilibrium charge carriers, although locally, dislocations are efficient recombination sites. In general, it is observed that the effect of the growth method [standard metalorganic chemical vapor deposition (MOCVD), epitaxial lateral overgrowth versions of MOCVD, and hydride vapor phase epitaxy] on the recombination activity of dislocations is not very pronounced, although the average diffusion lengths can widely differ for various samples. The glide of basal plane dislocations at room temperature promoted by low energy electron irradiation does not significantly change the recombination properties of dislocations.

  20. Quasicontinuum analysis of dislocation-coherent twin boundary interaction to provide local rules to discrete dislocation dynamics

    NASA Astrophysics Data System (ADS)

    Tran, H.-S.; Tummala, H.; Duchene, L.; Pardoen, T.; Fivel, M.; Habraken, A. M.

    2017-10-01

    The interaction of a pure screw dislocation with a Coherent Twin Boundary Σ3 in copper was studied using the Quasicontinuum method. Coherent Twin Boundary behaves as a strong barrier to dislocation glide and prohibits slip transmission across the boundary. Dislocation pileup modifies the stress field at its intersection with the Grain Boundary (GB). A methodology to estimate the strength of the barrier for a dislocation to slip across CTB is proposed. A screw dislocation approaching the boundary from one side either propagates into the adjacent twin grain by cutting through the twin boundary or is stopped and increases the dislocation pileup amplitude at the GB. Quantitative estimation of the critical stress for transmission was performed using the virial stress computed by Quasicontinuum method. The transmission mechanism and critical stress are in line with the literature. Such information can be used as input for dislocation dynamic simulations for a better modeling of grain boundaries.

  1. Fast Fourier transform discrete dislocation dynamics

    NASA Astrophysics Data System (ADS)

    Graham, J. T.; Rollett, A. D.; LeSar, R.

    2016-12-01

    Discrete dislocation dynamics simulations have been generally limited to modeling systems described by isotropic elasticity. Effects of anisotropy on dislocation interactions, which can be quite large, have generally been ignored because of the computational expense involved when including anisotropic elasticity. We present a different formalism of dislocation dynamics in which the dislocations are represented by the deformation tensor, which is a direct measure of the slip in the lattice caused by the dislocations and can be considered as an eigenstrain. The stresses arising from the dislocations are calculated with a fast Fourier transform (FFT) method, from which the forces are determined and the equations of motion are solved. Use of the FFTs means that the stress field is only available at the grid points, which requires some adjustments/regularizations to be made to the representation of the dislocations and the calculation of the force on individual segments, as is discussed hereinafter. A notable advantage of this approach is that there is no computational penalty for including anisotropic elasticity. We review the method and apply it in a simple dislocation dynamics calculation.

  2. Acute traumatic open posterolateral dislocation of the ankle without tearing of the tibiofibular syndesmosis ligaments: a case report.

    PubMed

    Demiralp, Bahtiyar; Komurcu, Mahmut; Ozturk, Cagatay; Ozturan, Kutay; Tasatan, Ersin; Erler, Kaan

    2008-01-01

    Pure open dislocation of the ankle, or dislocation not accompanied by rupture of the tibiofibular syndesmosis ligaments or fractures of the malleoli or of the posterior border of the tibia, is an extremely rare injury. A 62-year-old man injured his right ankle in a motor vehicle accident. Besides posterolateral ankle dislocation, there was a 7-cm transverse skin cut on the medial malleolus, and the distal end of the tibia was exposed. After reduction, we made a 2- to 2.5-cm longitudinal incision on the lateral malleolus; the distal fibular fracture was exposed. Two Kirschner wires were placed intramedullary in a retrograde manner, and the fracture was stabilized. The deltoid ligament and the medial capsule were repaired. The tibiofibular syndesmosis ligaments were intact. At the end of postoperative year 1, right ankle joint range of motion had a limit of approximately 5 degrees in dorsiflexion, 10 degrees in plantarflexion, 5 degrees in inversion, and 0 degrees in eversion. The joint appeared normal on radiographs, with no signs of osteoarthritis or calcification. The best result can be obtained with early reduction, debridement, medial capsule and deltoid ligament restoration, and early rehabilitation. Clinical and radiographic features at long-term follow-up also confirm good mobility of the ankle without degenerative change or mechanical instability.

  3. Theory of interacting dislocations on cylinders.

    PubMed

    Amir, Ariel; Paulose, Jayson; Nelson, David R

    2013-04-01

    We study the mechanics and statistical physics of dislocations interacting on cylinders, motivated by the elongation of rod-shaped bacterial cell walls and cylindrical assemblies of colloidal particles subject to external stresses. The interaction energy and forces between dislocations are solved analytically, and analyzed asymptotically. The results of continuum elastic theory agree well with numerical simulations on finite lattices even for relatively small systems. Isolated dislocations on a cylinder act like grain boundaries. With colloidal crystals in mind, we show that saddle points are created by a Peach-Koehler force on the dislocations in the circumferential direction, causing dislocation pairs to unbind. The thermal nucleation rate of dislocation unbinding is calculated, for an arbitrary mobility tensor and external stress, including the case of a twist-induced Peach-Koehler force along the cylinder axis. Surprisingly rich phenomena arise for dislocations on cylinders, despite their vanishing Gaussian curvature.

  4. Effectiveness of intra-articular lidocaine injection for reduction of anterior shoulder dislocation: randomized clinical trial.

    PubMed

    Tamaoki, Marcel Jun Sugawara; Faloppa, Flavio; Wajnsztejn, André; Archetti Netto, Nicola; Matsumoto, Marcelo Hide; Belloti, João Carlos

    2012-01-01

    Shoulder dislocation is the most common dislocation among the large joints. The aim here was to compare the effectiveness of reduction of acute anterior shoulder dislocation with or without articular anesthesia. Prospective randomized trial conducted in Escola Paulista de Medicina, Universidade Federal de São Paulo (EPM-Unifesp). From March 2008 to December 2009, 42 patients with shoulder dislocation were recruited. Reductions using traction-countertraction for acute anterior shoulder dislocation with and without lidocaine articular anesthesia were compared. As the primary outcome, pain was assessed through application of a visual analogue scale before reduction, and one and five minutes after the reduction maneuver was performed. Complications were also assessed. Forty-two patients were included: 20 in the group without analgesia (control group) and 22 in the group that received intra-articular lidocaine injection. The group that received intra-articular lidocaine had a statistically greater decrease in pain over time than shown by the control group, both in the first minute (respectively: mean 2.1 (0 to 5.0), standard deviation, SD 1.3, versus mean 4.9 (2.0 to 7.0, SD 1.5; P < 0.001) and the fifth minute (respectively: mean 1.0; 0 to 3.0; SD = 1.0 versus mean 4.0; 1.0 to 6.0; SD = 1.4; P < 0.001). There was one failure in the control group. There were no other complications in either group. Reduction of anterior shoulder dislocation using intra-articular lidocaine injection is effective, since it is safe and diminishes the pain. ISRCTN27127703.

  5. Dislocation pinning effects induced by nano-precipitates during warm laser shock peening: Dislocation dynamic simulation and experiments

    NASA Astrophysics Data System (ADS)

    Liao, Yiliang; Ye, Chang; Gao, Huang; Kim, Bong-Joong; Suslov, Sergey; Stach, Eric A.; Cheng, Gary J.

    2011-07-01

    Warm laser shock peening (WLSP) is a new high strain rate surface strengthening process that has been demonstrated to significantly improve the fatigue performance of metallic components. This improvement is mainly due to the interaction of dislocations with highly dense nanoscale precipitates, which are generated by dynamic precipitation during the WLSP process. In this paper, the dislocation pinning effects induced by the nanoscale precipitates during WLSP are systematically studied. Aluminum alloy 6061 and AISI 4140 steel are selected as the materials with which to conduct WLSP experiments. Multiscale discrete dislocation dynamics (MDDD) simulation is conducted in order to investigate the interaction of dislocations and precipitates during the shock wave propagation. The evolution of dislocation structures during the shock wave propagation is studied. The dislocation structures after WLSP are characterized via transmission electron microscopy and are compared with the results of the MDDD simulation. The results show that nano-precipitates facilitate the generation of highly dense and uniformly distributed dislocation structures. The dislocation pinning effect is strongly affected by the density, size, and space distribution of nano-precipitates.

  6. Glide Dislocations Dissociation in Inversion Domain Boundaries of Plastically Deformed Aluminium Nitride

    NASA Astrophysics Data System (ADS)

    Feregotto, Virginia; Michel, Jean-Pierre

    1996-09-01

    A ten per cent plastic deformation of polycrystalline aluminium nitride, at a temperature ranging from 1500 to 1650 ^{circ}C creates a new kind of intragranular defect. Observed by transmission electron microscopy, the look like torsion subboundaries created by dislocations with 1/3<~ngle11bar{2}0rangle Burgers vectors and so nodes are dissociated into Shockley partials. They are located in the basal plane. In fact, these defects appear only in the plane areas of grown-in defects, the inversion domain boundaries. The formation of these faulted networks is interpreted as being the ultimate stage of the interactions between inversion domain boundaries and glide dislocations. Une déformation plastique de 10 % de nitrure d'aluminium polycristallin, entre 1500 et 1650 ^{circ}C introduit un nouveau type de défauts intragranulaires. Au microscope électronique par transmission, ils apparaissent comme des sous-joints de torsion créés par des dislocations de vecteurs de Burgers 1/3<~ngle11bar{2}0rangle dont les nœuds triples sont dissociés en partielles de Shockley ; ils sont situés dans le plan de base. En fait, ces défauts ne se produisent que sur les parties planes de défauts originels, les parois de domaines d'inversion. La formation de ces réseaux fautés est analysée comme l'ultime stade des interactions entre parois de domaines d'inversion et dislocations de glissement.

  7. Restoration of horizontal stability in complete acromioclavicular joint separations: surgical technique and preliminary results.

    PubMed

    Li, Haoqing; Wang, Chuanshun; Wang, Jiandong; Wu, Kai; Hang, Donghua

    2013-11-13

    Our purpose was to investigate the clinical efficacy of arthroscope-assisted acromioclavicular ligament reconstruction in combination with double endobutton coracoclavicular ligament reconstruction for the treatment of complete acromioclavicular joint dislocation. During the period from February 2010 to October 2012, ten patients with Rockwood types IV and V acromioclavicular joint dislocation were hospitalized and nine were treated with acromioclavicular ligament reconstruction combined with double endobutton of coracoclavicular ligament reconstruction. The improvement in shoulder functions was assessed using a Constant score and visual analog scale (VAS) system. The mean follow-up period was 33.6 ± 5.4 months. The mean Constant scores improved from 25.2 ± 6.6 preoperatively to 92.4 ± 6.5 postoperatively, while the mean VAS score decreased from 5.9 ± 1.4 to 1.2 ± 0.9; significant differences were observed. The final follow-up revealed that excellent outcomes were achieved in eight patients and good outcome in two patients. Arthroscope-assisted acromioclavicular ligament reconstruction in combination with double endobutton of coracoclavicular ligament reconstruction is an effective approach for treatment of acute complete acromioclavicular joint dislocation.

  8. Early osteoarthritis of the patellofemoral joint.

    PubMed

    Arendt, Elizabeth A; Berruto, Massimo; Filardo, Giuseppe; Ronga, Mario; Zaffagnini, Stefano; Farr, Jack; Ferrua, Paolo; Grassi, Alberto; Condello, Vincenzo

    2016-06-01

    Patellofemoral joint cartilage lesions are associated with a variety of clinical situations including blunt trauma, lateral patella dislocations, or as a secondary development in the setting of abnormal joint loading. There is a need for more clarity on how to best address these lesions. Most specifically, when is it necessary to surgically treat these lesions of the patella and trochlea and which technique to use? This review will focus on the spectrum of patellofemoral disease/injury and their treatment strategies, with special emphasis on cartilage damage and early osteoarthritis. Chapter sections will review the most common scenarios of cartilage damage in the patellofemoral joint, with an attempt to summarize current treatment, their outcomes, remaining challenges and unanswered questions.

  9. [The hip joint in neuromuscular disorders].

    PubMed

    Strobl, W M

    2009-07-01

    Physiologic motor and biomechanical parameters are prerequisites for normal hip development and hip function. Disorders of muscle activity and lack of weight bearing due to neuromuscular diseases may cause clinical symptoms such as an unstable hip or reduced range of motion. Disability and handicap because of pain, hip dislocation, osteoarthritis, gait disorders, or problems in seating and positioning are dependent on the severity of the disease, the time of occurrence, and the means of prevention and treatment. Preservation of pain-free and stable hip joints should be gained by balancing muscular forces and by preventing progressive dislocation. Most important is the exact indication of therapeutic options such as movement and standing therapy as well as drugs and surgery.

  10. Misfit dislocation patterns of Mg-Nb interfaces

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Chen, Youxing; Shao, Shuai; Liu, Xiang-Yang

    The role of heterogeneous interfaces in improving mechanical properties of polycrystalline aggregates and laminated composites has been well recognized with interface structure being of fundamental importance in designing composites containing multiple interfaces. In this paper, taking the Mg (hexagonal close-packed (hcp))/Nb (body-centered cubic (bcc)) interface as an example, we develop Mg-Nb interatomic potentials for predicting atomic configurations of Mg/Nb interfaces. We systematically characterize interface dislocations of Mg/Nb interfaces with Nishiyama-Wassermann (NW) and Kurdjumov-Sachs (KS) orientation relationships and propose a generalized procedure of characterizing interface structure by combining atomistic simulation and interface dislocation theory, which is applicable for not only hcp/bccmore » interfaces, but also other systems with complicated interface dislocation configurations.Here, in Mg/Nb, interface dislocation networks of two types of interfaces are significantly different although they originate from partial dislocations of similar character: the NW interface is composed of three sets of partial dislocations, while the KS interface is composed of four sets of interface dislocations - three sets of partial dislocations and one set of full dislocations that forms from the reaction of two close partial dislocations.« less

  11. Probing the character of ultra-fast dislocations

    DOE PAGES

    Rudd, R. E.; Ruestes, C. J.; Bringa, E. M.; ...

    2015-11-23

    Plasticity is often controlled by dislocation motion, which was first measured for low pressure, low strain rate conditions decades ago. However, many applications require knowledge of dislocation motion at high stress conditions where the data are sparse, and come from indirect measurements dominated by the effect of dislocation density rather than velocity. Here we make predictions based on atomistic simulations that form the basis for a new approach to measure dislocation velocities directly at extreme conditions using three steps: create prismatic dislocation loops in a near-surface region using nanoindentation, drive the dislocations with a shockwave, and use electron microscopy tomore » determine how far the dislocations moved and thus their velocity at extreme stress and strain rate conditions. We report on atomistic simulations of tantalum that make detailed predictions of dislocation flow, and find that the approach is feasible and can uncover an exciting range of phenomena, such as transonic dislocations and a novel form of loop stretching. Furthermore, the simulated configuration enables a new class of experiments to probe average dislocation velocity at very high applied shear stress.« less

  12. Study on the Tensile Creep Behavior of Carbon Nanotubes-Reinforced Sn-58Bi Solder Joints

    NASA Astrophysics Data System (ADS)

    Yang, Li; Liu, Haixiang; Zhang, Yaocheng

    2018-01-01

    The microstructure and tensile creep behavior of plain Sn-58Bi solder and carbon nanotubes (CNTs)-reinforced composite solder joints were investigated. The stress exponent n under different stresses and the creep activation energy Q c under different temperatures of solder joints were obtained by an empirical equation. The results reveal that the microstructure of the composite solder joint is refined and the tensile creep resistance is improved by CNTs. The improvement of creep behavior is due to the microstructural change of the composite solder joints, since the CNTs could provide more obstacles for dislocation pile-up, which enhances the values of the stress exponent and the creep activation energy. The steady-state tensile creep rates of plain solder and composite solder joints are increased with increasing temperature and applied stress. The tensile creep constitutive equations of plain solder and composite solder joints are written as \\dot{ɛ }_{s1} = 14.94( {σ /G} )^{3.7} \\exp ( { - 81444/RT} ) and \\dot{ɛ }_{s2} = 2.5( {σ /G} )^{4.38} \\exp ( { - 101582/RT} ) , respectively. The tensile creep mechanism of the solder joints is the effects of lattice diffusion determined by dislocation climbing.

  13. EXTRA-ARTICULAR FRACTURE OF THE MEDIAL END OF THE CLAVICLE ASSOCIATED WITH TYPE IV ACROMIOCLAVICULAR DISLOCATION: CAAE REPORT

    PubMed Central

    Correa, Mário Chaves; Gonçalves, Lucas Braga Jacques; Vilela, Jose Carlos Souza; Leonel, Igor Lima; Costa, Lincoln Paiva; de Andrade, Ronaldo Percopi

    2015-01-01

    Fractures of the clavicle and acromioclavicular dislocations are very common injuries when they occur separately. The combination of an acromioclavicular dislocation and a fracture of the lateral third of the clavicle is not rare. However, there are very few reported cases of acromioclavicular dislocations associated with fractures of the middle third of the clavicle; those associated with fractures of the medial third are even rarer. We report the case of an adult male who suffered an acromioclavicular dislocation (type IV) associated with a displaced extra-articular fracture of the medial end of the clavicle (Almann group 3) in a cycling accident. The patient was treated during the acute phase with open reduction and internal fixation of the two lesions. At the clinical evaluation 12 months after the surgery, the patient was asymptomatic, with full active and passive mobility, and normal strength and endurance of the shoulder girdle. Radiographs and a three-dimensional CT scan showed persistent posterosuperior subluxation of the acromioclavicular joint and anatomical consolidation of the clavicular fracture. PMID:27027060

  14. EXTRA-ARTICULAR FRACTURE OF THE MEDIAL END OF THE CLAVICLE ASSOCIATED WITH TYPE IV ACROMIOCLAVICULAR DISLOCATION: CAAE REPORT.

    PubMed

    Correa, Mário Chaves; Gonçalves, Lucas Braga Jacques; Vilela, Jose Carlos Souza; Leonel, Igor Lima; Costa, Lincoln Paiva; de Andrade, Ronaldo Percopi

    2011-01-01

    Fractures of the clavicle and acromioclavicular dislocations are very common injuries when they occur separately. The combination of an acromioclavicular dislocation and a fracture of the lateral third of the clavicle is not rare. However, there are very few reported cases of acromioclavicular dislocations associated with fractures of the middle third of the clavicle; those associated with fractures of the medial third are even rarer. We report the case of an adult male who suffered an acromioclavicular dislocation (type IV) associated with a displaced extra-articular fracture of the medial end of the clavicle (Almann group 3) in a cycling accident. The patient was treated during the acute phase with open reduction and internal fixation of the two lesions. At the clinical evaluation 12 months after the surgery, the patient was asymptomatic, with full active and passive mobility, and normal strength and endurance of the shoulder girdle. Radiographs and a three-dimensional CT scan showed persistent posterosuperior subluxation of the acromioclavicular joint and anatomical consolidation of the clavicular fracture.

  15. Surgical Dislocation of the Hip for the Treatment of Pre-Arthritic Hip Disease.

    PubMed

    Beaulé, Paul E; Singh, Amardeep; Poitras, Stéphane; Parker, Gillian

    2015-09-01

    The purpose of this study was to report the clinical results of surgical dislocation of the hip in the treatment of pre-arthritic hip disease. Between 2005 and 2010, eighty-two patients (89 hips) underwent a surgical dislocation of the hip at a mean age of 30.5 years (range 14.8-51.7); 10 females and 72 males. At a mean follow-up of 7.1 years (range 5-9.6) clinical function improved significantly. 6 patients were converted to total hip arthroplasty and 3 patients underwent an arthroscopy and an additional three patients had >1mm of joint space narrowing at latest follow-up giving us a 9-year cumulative Kaplan-Meier survivorship of 86.4% (CI, 79% to 94%). Thirty-four patients underwent internal fixation removal at a mean of 12.0 months (range 0.3-40.8 months). Although effective in the treatment of early hip disease, the surgical dislocation approach carries a high re-operation rate for removal of internal fixation; consequently, less invasive approaches should be considered for less complex deformities. Copyright © 2015 Elsevier Inc. All rights reserved.

  16. Worker Dislocation. Case Studies of Causes and Cures.

    ERIC Educational Resources Information Center

    Cook, Robert F., Ed.

    Case studies were made of the following dislocated worker programs: Cummins Engine Company Dislocated Worker Project; GM-UAW Metropolitan Pontiac Retraining and Employment Program; Minnesota Iron Range Dislocated Worker Project; Missouri Dislocated Worker Program Job Search Assistance, Inc.; Hillsborough, North Carolina, Dislocated Worker Project;…

  17. Acromioclavicular joint injuries in the National Football League: epidemiology and management.

    PubMed

    Lynch, T Sean; Saltzman, Matthew D; Ghodasra, Jason H; Bilimoria, Karl Y; Bowen, Mark K; Nuber, Gordon W

    2013-12-01

    Previous studies investigating acromioclavicular (AC) joint injuries in professional American football players have only been reported on quarterbacks during the 1980s and 1990s. These injuries have not been evaluated across all position players in the National Football League (NFL). The purpose of this study was 4-fold: (1) to determine the incidence of AC joint injuries among all NFL position players; (2) to investigate whether player position, competition setting, type of play, and playing surface put an athlete at an increased risk for this type of injury; (3) to determine the incidence of operative and nonoperative management of these injuries; and (4) to compare the time missed for injuries treated nonoperatively to the time missed for injuries requiring surgical intervention. Descriptive epidemiological study. All documented injuries of the AC joint were retrospectively analyzed using the NFL Injury Surveillance System (NFLISS) over a 12-season period from 2000 through 2011. The data were analyzed by the anatomic location, player position, field conditions, type of play, requirement of surgical management, days missed per injury, and injury incidence. Over 12 NFL seasons, there were a total of 2486 shoulder injuries, with 727 (29.2%) of these injuries involving the AC joint. The overall rate of AC joint injuries in these athletes was 26.1 injuries per 10,000 athlete exposures, with the majority of these injuries occurring during game activity on natural grass surfaces (incidence density ratio, 0.79) and most often during passing plays. These injuries occurred most frequently in defensive backs, wide receivers, and special teams players; however, the incidence of these injuries was greatest in quarterbacks (20.9 injuries per 100 players), followed by special teams players (20.7/100) and wide receivers (16.5/100). Overall, these athletes lost a mean of 9.8 days per injury, with quarterbacks losing the most time to injury (mean, 17.3 days). The majority of

  18. Dislocation mechanisms in stressed crystals with surface effects

    NASA Astrophysics Data System (ADS)

    Wu, Chi-Chin; Crone, Joshua; Munday, Lynn; Discrete Dislocation Dynamics Team

    2014-03-01

    Understanding dislocation properties in stressed crystals is the key for important processes in materials science, including the strengthening of metals and the stress relaxation during the growth of hetero-epitaxial structures. Despite existing experimental approaches and theories, many dislocation mechanisms with surface effects still remain elusive in experiments. Even though discrete dislocation dynamics (DDD) simulations are commonly employed to study dislocations, few demonstrate sufficient computational capabilities for massive dislocations with the combined effects of surfaces and stresses. Utilizing the Army's newly developed FED3 code, a DDD computation code coupled with finite elements, this work presents several dislocation mechanisms near different types of surfaces in finite domains. Our simulation models include dislocations in a bended metallic cantilever beam, near voids in stressed metals, as well as threading and misfit dislocations in as-grown semiconductor epitaxial layers and their quantitative inter-correlations to stress relaxation and surface instability. Our studies provide not only detailed physics of individual dislocation mechanisms, but also important collective dislocation properties such as dislocation densities and strain-stress profiles and their interactions with surfaces.

  19. Intraoperative dislocation of the trial bipolar cup into the pelvis during bipolar hip arthroplasty - A case report.

    PubMed

    Miyake, Takahito; Kanda, Akio; Morohashi, Itaru; Obayashi, Osamu; Mogami, Atsuhiko; Kaneko, Kazuo

    2017-06-01

    Bipolar hip arthroplasty is a good option for treating femoral neck fractures, although some contraindications have been indicated. We report a case of intraoperative dislocation of the trial bipolar cup into the pelvis during bipolar hip arthroplasty. A 74-year-old woman underwent bipolar hip arthroplasty for a femoral neck fracture (AO31-B2). She was placed in a lateral decubitus position, and a direct lateral approach was used. During intraoperative trial reduction, the trial bipolar cup became disengaged and dislocated into the anterior space of hip joint. Several attempts to retrieve it failed. The permanent femoral component was inserted, and the wound was closed. The patient was repositioned supine to allow an ilioinguinal approach, and the component was easily removed. She had an uneventful, good recovery. Several cases of intraoperative dislocation of the femoral trial head during total hip arthroplasty have been reported, this is the first report of dislocation of a bipolar trial cup. A previous report described difficulty retrieving a trial cup. We easily removed our trial cup using another approach. It is vital to plan systematically for this frustrating complication.

  20. Dislocation dynamics in hexagonal close-packed crystals

    DOE PAGES

    Aubry, S.; Rhee, M.; Hommes, G.; ...

    2016-04-14

    Extensions of the dislocation dynamics methodology necessary to enable accurate simulations of crystal plasticity in hexagonal close-packed (HCP) metals are presented. They concern the introduction of dislocation motion in HCP crystals through linear and non-linear mobility laws, as well as the treatment of composite dislocation physics. Formation, stability and dissociation of and other dislocations with large Burgers vectors defined as composite dislocations are examined and a new topological operation is proposed to enable their dissociation. Furthermore, the results of our simulations suggest that composite dislocations are omnipresent and may play important roles both in specific dislocation mechanisms and in bulkmore » crystal plasticity in HCP materials. While fully microscopic, our bulk DD simulations provide wealth of data that can be used to develop and parameterize constitutive models of crystal plasticity at the mesoscale.« less

  1. Comparison of dislocation density tensor fields derived from discrete dislocation dynamics and crystal plasticity simulations of torsion

    DOE PAGES

    Jones, Reese E.; Zimmerman, Jonathan A.; Po, Giacomo; ...

    2016-02-01

    Accurate simulation of the plastic deformation of ductile metals is important to the design of structures and components to performance and failure criteria. Many techniques exist that address the length scales relevant to deformation processes, including dislocation dynamics (DD), which models the interaction and evolution of discrete dislocation line segments, and crystal plasticity (CP), which incorporates the crystalline nature and restricted motion of dislocations into a higher scale continuous field framework. While these two methods are conceptually related, there have been only nominal efforts focused at the global material response that use DD-generated information to enhance the fidelity of CPmore » models. To ascertain to what degree the predictions of CP are consistent with those of DD, we compare their global and microstructural response in a number of deformation modes. After using nominally homogeneous compression and shear deformation dislocation dynamics simulations to calibrate crystal plasticity ow rule parameters, we compare not only the system-level stress-strain response of prismatic wires in torsion but also the resulting geometrically necessary dislocation density fields. To establish a connection between explicit description of dislocations and the continuum assumed with crystal plasticity simulations we ascertain the minimum length-scale at which meaningful dislocation density fields appear. Furthermore, our results show that, for the case of torsion, that the two material models can produce comparable spatial dislocation density distributions.« less

  2. Restoration of horizontal stability in complete acromioclavicular joint separations: surgical technique and preliminary results

    PubMed Central

    2013-01-01

    Background Our purpose was to investigate the clinical efficacy of arthroscope-assisted acromioclavicular ligament reconstruction in combination with double endobutton coracoclavicular ligament reconstruction for the treatment of complete acromioclavicular joint dislocation. Methods During the period from February 2010 to October 2012, ten patients with Rockwood types IV and V acromioclavicular joint dislocation were hospitalized and nine were treated with acromioclavicular ligament reconstruction combined with double endobutton of coracoclavicular ligament reconstruction. The improvement in shoulder functions was assessed using a Constant score and visual analog scale (VAS) system. Results The mean follow-up period was 33.6 ± 5.4 months. The mean Constant scores improved from 25.2 ± 6.6 preoperatively to 92.4 ± 6.5 postoperatively, while the mean VAS score decreased from 5.9 ± 1.4 to 1.2 ± 0.9; significant differences were observed. The final follow-up revealed that excellent outcomes were achieved in eight patients and good outcome in two patients. Conclusion Arthroscope-assisted acromioclavicular ligament reconstruction in combination with double endobutton of coracoclavicular ligament reconstruction is an effective approach for treatment of acute complete acromioclavicular joint dislocation. PMID:24225119

  3. Ultrasonic influence on evolution of disordered dislocation structures

    NASA Astrophysics Data System (ADS)

    Bachurin, D. V.; Murzaev, R. T.; Nazarov, A. A.

    2017-12-01

    Evolution of disordered dislocation structures under ultrasonic influence is studied in a model two-dimensional grain within the discrete-dislocation approach. Non-equilibrium grain boundary state is mimicked by a mesodefect located at the corners of the grain, stress field of which is described by that of a wedge junction disclination quadrupole. Significant rearrangement related to gliding of lattice dislocations towards the grain boundaries is found, which results in a noticeable reduction of internal stress fields and cancel of disclination quadrupole. The process of dislocation structure evolution passes through two stages: rapid and slow. The main dislocation rearrangement occurs during the first stage. Reduction of internal stress fields is associated with the number of dislocations entered into the grain boundaries. The change of misorientation angle due to lattice dislocations absorbed by the grain boundaries is evaluated. Amplitude of ultrasonic treatment significantly influences the relaxation of dislocation structure. Preliminary elastic relaxation of dislocation structure does not affect substantially the results of the following ultrasonic treatment. Substantial grain size dependence of relaxation of disordered dislocation systems is found. Simulation results are consistent with experimental data.

  4. Neglected locked vertical patellar dislocation

    PubMed Central

    Gupta, Rakesh Kumar; Gupta, Vinay; Sangwan, Sukhbir Singh; Kamboj, Pradeep

    2012-01-01

    Patellar dislocations occurring about the vertical and horizontal axis are rare and irreducible. The neglected patellar dislocation is still rarer. We describe the clinical presentation and management of a case of neglected vertical patellar dislocation in a 6 year-old boy who sustained an external rotational strain with a laterally directed force to his knee. Initially the diagnosis was missed and 2 months later open reduction was done. The increased tension generated by the rotation of the lateral extensor retinaculum kept the patella locked in the lateral gutter even with the knee in full extension. Traumatic patellar dislocation with rotation around a vertical axis has been described earlier, but no such neglected case has been reported to the best of our knowledge. PMID:23162154

  5. External fixation combined with delayed internal fixation in treatment of tibial plateau fractures with dislocation.

    PubMed

    Tao, Xingguang; Chen, Nong; Pan, Fugen; Cheng, Biao

    2017-10-01

    The aim of this study was to evaluate the clinical efficacy of external fixation, delayed open reduction, and internal fixation in treating tibial plateau fracture with dislocation.Clinical data of 34 patients diagnosed with tibial plateau fracture complicated with dislocation between January 2009 and May 2015 were retrospectively analyzed. Fifteen patients in group A underwent early calcaneus traction combined with open reduction and internal fixation and 19 in group B received early external fixation combined with delayed open reduction and internal fixation. Operation time, postoperative complication, bone healing time, knee joint range of motion, initial weight-bearing time, Rasmussen tibial plateau score, and knee function score (HSS) were statistically compared between 2 groups.The mean follow-up time was 18.6 months (range: 5-24 months). The mean operation time in group A was 96 minutes, significantly longer than 71 minutes in group B (P < .05). In group A, 5 cases had postoperative complications and 1 in group B (P < .05). The mean bone healing time in group A was 6.9 months (range: 5-9 months) and 6.0 months (range: 5-8 months) in group B (P > .05). In group A, initial weight-bearing time in group A was (14.0 ± 3.6) weeks, significantly differing from (12.9 ± 2.8) weeks in group B (P < 0.05). In group A, the mean knee joint range of motion was 122° (range: 95°-150°) and 135° (range: 100°-160°) in group B (P > 0.05). Rasmussen tibial plateau score in group A was slightly lower than that in group B (P > .05). The excellent rate of knee joint function in group A was 80% and 84.21% in group B (P > .05).External fixation combined with delayed open reduction and internal fixation is a safer and more efficacious therapy of tibial plateau fracture complicated with dislocation compared with early calcaneus traction and open reduction and internal fixation.

  6. Thermodynamic dislocation theory: Bauschinger effect

    NASA Astrophysics Data System (ADS)

    Le, K. C.; Tran, T. M.

    2018-04-01

    The thermodynamic dislocation theory developed for nonuniform plastic deformations is used here to simulate the stress-strain curves for crystals subjected to antiplane shear-controlled load reversal. We show that the presence of the positive back stress during the load reversal reduces the magnitude of shear stress required to pull excess dislocations back to the center of the specimen. There, the excess dislocations of opposite signs meet and annihilate each other leading to the Bauschinger effect.

  7. Acromioclavicular joint reconstruction using the LockDown synthetic implant: a study with cadavers.

    PubMed

    Taranu, R; Rushton, P R P; Serrano-Pedraza, I; Holder, L; Wallace, W A; Candal-Couto, J J

    2015-12-01

    Dislocation of the acromioclavicular joint is a relatively common injury and a number of surgical interventions have been described for its treatment. Recently, a synthetic ligament device has become available and been successfully used, however, like other non-native solutions, a compromise must be reached when choosing non-anatomical locations for their placement. This cadaveric study aimed to assess the effect of different clavicular anchorage points for the Lockdown device on the reduction of acromioclavicular joint dislocations, and suggest an optimal location. We also assessed whether further stability is provided using a coracoacromial ligament transfer (a modified Neviaser technique). The acromioclavicular joint was exposed on seven fresh-frozen cadaveric shoulders. The joint was reconstructed using the Lockdown implant using four different clavicular anchorage points and reduction was measured. The coracoacromial ligament was then transferred to the lateral end of the clavicle, and the joint re-assessed. If the Lockdown ligament was secured at the level of the conoid tubercle, the acromioclavicular joint could be reduced anatomically in all cases. If placed medial or 2 cm lateral, the joint was irreducible. If the Lockdown was placed 1 cm lateral to the conoid tubercle, the joint could be reduced with difficulty in four cases. Correct placement of the Lockdown device is crucial to allow anatomical joint reduction. Even when the Lockdown was placed over the conoid tubercle, anterior clavicle displacement remained but this could be controlled using a coracoacromial ligament transfer. ©2015 The British Editorial Society of Bone & Joint Surgery.

  8. [The Postero-Lateral Approach--An Alternative to Closed Anterior-Posterior Screw Fixation of a Dislocated Postero-Lateral Fragment of the Distal Tibia in Complex Ankle Fractures].

    PubMed

    von Rüden, C; Hackl, S; Woltmann, A; Friederichs, J; Bühren, V; Hierholzer, C

    2015-06-01

    The dislocated posterolateral fragment of the distal tibia is considered as a key fragment for the successful reduction of comminuted ankle fractures. The reduction of this fragment can either be achieved indirectly by joint reduction using the technique of closed anterior-posterior screw fixation, or directly using the open posterolateral approach followed by plate fixation. The aim of this study was to compare the outcome after stabilization of the dislocated posterolateral tibia fragment using either closed reduction and screw fixation, or open reduction and plate fixation via the posterolateral approach in complex ankle fractures. In a prospective study between 01/2010 and 12/2012, all mono-injured patients with closed ankle fractures and dislocated posterolateral tibia fragments were assessed 12 months after osteosynthesis. Parameters included: size of the posterolateral tibia fragment relative to the tibial joint surface (CT scan, in %) as an indicator of injury severity, unreduced area of tibial joint surface postoperatively, treatment outcome assessed by using the "Ankle Fracture Scoring System" (AFSS), as well as epidemiological data and duration of the initial hospital treatment. In 11 patients (10 female, 1 male; age 51.6 ± 2.6 years [mean ± SEM], size of tibia fragment 42.1 ± 2.5 %) the fragment fixation was performed using a posterolateral approach. Impaired postoperative wound healing occurred in 2 patients of this group. In the comparison group, 12 patients were treated using the technique of closed anterior-posterior screw fixation (10 female, 2 male; age 59.5 ± 6.7 years, size of tibia fragment 45.9 ± 1.5 %). One patient of this group suffered an incomplete lesion of the superficial peroneal nerve. Radiological evaluation of the joint surface using CT scan imaging demonstrated significantly less dislocation of the tibial joint surface following the open posterolateral approach (0.60 ± 0.20 mm) compared to the closed

  9. Palpation Versus Ultrasound-Guided Acromioclavicular Joint Intra-articular Corticosteroid Injections: A Retrospective Comparative Clinical Study.

    PubMed

    Park, Ki Deok; Kim, Tai Kon; Lee, Jihae; Lee, Woo Yong; Ahn, Jae Ki; Park, Yongbum

    2015-01-01

    Primary osteoarthritis (OA) is the most common cause of pain arising from the acromioclavicular (AC) joint. The true incidence is unknown because of differences in the criteria used to define arthritis in various studies. The proper diagnosis of AC joint OA requires a thorough physical examination, radiographic findings, and a diagnostic local anesthetic injection. The goal of this study was to assess the effects and safety of ultrasound (US) versus palpation-guided acromioclavicular (AC) joint intra-articular (IA) corticosteroid injection for patients with osteoarthritis (OA) of the AC joint. Retrospective, compared clinical study. University hospital outpatient pain clinic. We retrospectively reviewed the charts of patients with AC joint degenerative OA who had undergone US or palpation-guided AC joint IA corticosteroid injection between January 2012 and December 2013 at our outpatient clinic. One hundred consecutive patients identified from chart review met inclusion criteria. Patients (N = 50) in US guide AC joint IA steroid injection group were administered a mixture of 0.5% lidocaine (1 mL) with triamcinolone (20 mg/mL; 0.5 mL) and radiographic contrast material (0.5 mL) and patients (N = 50) in palpation-guided AC joint IA steroid injection group were administered a mixture of 0.5% lidocaine (1 mL) with triamcinolone (20 mg/mL; 0.5 mL) and 0.5 mL of radiographic contrast material. Results were measured using the Shoulder Pain and Disability Index (SPADI), Verbal Numeric pain Scale (VNS) at rest (VNSar), under local pressure (VNSlp) ,and the arm adduction test (VNSaat) at the joint space area before injections and at one, 3, and 6 months after the injections. Successful treatment occurred when patients obtained significant pain relief (as measured by > 50% improvement in the VNS score and 20 point improvement in the SPADI) at one, 3, and 6 months after the injections. Univariable analysis was performed to evaluate the relationship between possible outcome

  10. [The Significance of Early Reposition in Patients with Visible Malposition of the Upper Ankle Joint].

    PubMed

    Wohlrath, B; Schweigkofler, U; Barzen, S; Heinz, S M; Schmidt-Horlohé, K; Hoffmann, R

    2016-12-01

    Background: Protracted dislocation of the upper ankle joint can lead to substantial damage to the surrounding soft tissue, possibly followed by local complications and longer hospitalisation. Although reposition is usually easy to conduct, it is commonly recommended that this should only be performed by an experienced specialist, as long as there is no neurovascular restriction. There are however no exact data or studies on this problem. The aim of the present study is to examine whether early reposition is of benefit for subsequent treatment. Methods: Retrospective study of all patients in a supra-regional trauma centre during the period from January 2009 to July 2015, with either prehospital reposition of the ankle joint because of visible malposition or documented visible malposition on arrival at hospital. Patients with relevant concomitant injuries elsewhere were excluded. Data on the duration of dislocation were matched with diagnostic findings at the time of hospital admission, the kind of primary care, local complications and the time of hospitalisation, using linear regression analysis and ANOVA calculations. Results: Of a total of 391 patients with a dislocation or a fracture dislocation of the ankle joint within this period, 132 fulfilled the inclusion criteria. These patients were divided into 5 groups on the basis of the time of dislocation. Time to reposition was less than one hour for 39 patients, between one and two hours for 29 patients, between two and six hours for 41 patients, between six and 24 hours for 13 patients and more than 24 hours for 10 patients, all with a visible dislocation. The results on admission showed a significant increase in skin bruises and tension bullae with increasing time of dislocation. A longer time of dislocation was associated with more two stage surgical procedures with external fixators and a decreasing number of single stage procedures. While there was immediate definitive treatment of 79.5 % of the patients in

  11. Internal stresses, dislocation mobility and ductility

    NASA Astrophysics Data System (ADS)

    Saada, G.

    1991-06-01

    The description of plastic deformation must take into account individual mechanisms and heterogeneity of plastic strain. Influence of dislocation interaction with forest dislocations and of cross slip are connected with the organization of dipole walls. The latter are described and their development is explained as a consequence of edge effects. Applications are discussed. La description de la déformation plastique doit prendre en compte les interactions individuelles des dislocations et l'hétérogénéité à grande échelle de la déformation plastique. Les interactions des dislocations mobiles avec la forêt de dislocations, le glissement dévié, ont pour effet la création de parois dipolaires. Celles-ci sont décrites et leur développement est appliqué à partir des effets de bord.

  12. Understanding dislocation mechanics at the mesoscale using phase field dislocation dynamics

    PubMed Central

    Hunter, A.

    2016-01-01

    In this paper, we discuss the formulation, recent developments and findings obtained from a mesoscale mechanics technique called phase field dislocation dynamics (PFDD). We begin by presenting recent advancements made in modelling face-centred cubic materials, such as integration with atomic-scale simulations to account for partial dislocations. We discuss calculations that help in understanding grain size effects on transitions from full to partial dislocation-mediated slip behaviour and deformation twinning. Finally, we present recent extensions of the PFDD framework to alternative crystal structures, such as body-centred cubic metals, and two-phase materials, including free surfaces, voids and bi-metallic crystals. With several examples we demonstrate that the PFDD model is a powerful and versatile method that can bridge the length and time scales between atomistic and continuum-scale methods, providing a much needed understanding of deformation mechanisms in the mesoscale regime. PMID:27002063

  13. AC losses in (Bi,Pb) 2Sr 2Ca 2Cu 3O x tapes

    NASA Astrophysics Data System (ADS)

    D'Anna, G.; Indenbom, M. V.; André, M.-O.; Benoit, W.; Grivel, J.-C.; Hensel, B.; Flükiger, R.

    1994-05-01

    A double peak structure is observed in the AC losses of (Bi,Pb) 2Sr 2Ca 2Cu 3O x silver-sheathed tapes using a torsion-pendulum oscillator. The low-temperature peak is associated to the intragrain flux expulsion, while the high-temperature peak results from a macroscopic current path around the whole sample due to a well-coupled fraction of the grains. The flux pinning by the dislocations forming small-angle grain boundaries is suggested to control the transport current.

  14. Atomistic calculations of dislocation core energy in aluminium

    DOE PAGES

    Zhou, X. W.; Sills, R. B.; Ward, D. K.; ...

    2017-02-16

    A robust molecular dynamics simulation method for calculating dislocation core energies has been developed. This method has unique advantages: it does not require artificial boundary conditions, is applicable for mixed dislocations, and can yield highly converged results regardless of the atomistic system size. Utilizing a high-fidelity bond order potential, we have applied this method in aluminium to calculate the dislocation core energy as a function of the angle β between the dislocation line and Burgers vector. These calculations show that, for the face-centred-cubic aluminium explored, the dislocation core energy follows the same functional dependence on β as the dislocation elasticmore » energy: Ec = A·sin 2β + B·cos 2β, and this dependence is independent of temperature between 100 and 300 K. By further analysing the energetics of an extended dislocation core, we elucidate the relationship between the core energy and radius of a perfect versus extended dislocation. With our methodology, the dislocation core energy can be accurately accounted for in models of plastic deformation.« less

  15. Atomistic calculations of dislocation core energy in aluminium

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Zhou, X. W.; Sills, R. B.; Ward, D. K.

    A robust molecular dynamics simulation method for calculating dislocation core energies has been developed. This method has unique advantages: it does not require artificial boundary conditions, is applicable for mixed dislocations, and can yield highly converged results regardless of the atomistic system size. Utilizing a high-fidelity bond order potential, we have applied this method in aluminium to calculate the dislocation core energy as a function of the angle β between the dislocation line and Burgers vector. These calculations show that, for the face-centred-cubic aluminium explored, the dislocation core energy follows the same functional dependence on β as the dislocation elasticmore » energy: Ec = A·sin 2β + B·cos 2β, and this dependence is independent of temperature between 100 and 300 K. By further analysing the energetics of an extended dislocation core, we elucidate the relationship between the core energy and radius of a perfect versus extended dislocation. With our methodology, the dislocation core energy can be accurately accounted for in models of plastic deformation.« less

  16. Novel utilization of 3D technology and the hybrid operating theatre: Peri-operative assessment of posterior sterno-clavicular dislocation using cone beam CT

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Crowhurst, James A; Campbell, Douglas; Whitby, Mark

    A patient with a medial and posterior dislocation of the right sterno-clavicular (SC) joint and displacement of the trachea and brachiocephalic artery by the medial head of the clavicle underwent general anaesthetic in the operating theatre for an open reduction procedure. The surgeon initially attempted a closed reduction, but this required imaging to check SC alignment. The patient was transferred to an adjacent hybrid operating theatre for imaging. Cone beam computed tomography (CBCT) was performed, which successfully demonstrated a significant reduction in the dislocation of the SC joint. The trachea and brachiocephalic artery were no longer compressed or displaced. Thismore » case study demonstrates an alternative to the patient being transferred to the medical imaging department for multi-slice CT. It also describes a novel use of the hybrid operating theatre and its CBCT capabilities.« less

  17. The rate of dislocation is not increased when minimal precautions are used after total hip arthroplasty using the posterolateral approach: a prospective, comparative safety study.

    PubMed

    Kornuijt, A; Das, D; Sijbesma, T; van der Weegen, W

    2016-05-01

    In order to prevent dislocation of the hip after total hip arthroplasty (THA), patients have to adhere to precautions in the early post-operative period. The hypothesis of this study was that a protocol with minimal precautions after primary THA using the posterolateral approach would not increase the short-term (less than three months) risk of dislocation. We prospectively monitored a group of unselected patients undergoing primary THA managed with standard precautions (n = 109, median age 68.9 years; interquartile range (IQR) 61.2 to 77.3) and a group who were managed with fewer precautions (n = 108, median age 67.2 years; IQR 59.8 to 73.2). There were no significant differences between the groups in relation to predisposing risk factors. The diameter of the femoral head ranged from 28 mm to 36 mm; meticulous soft-tissue repair was undertaken in all patients. The medical records were reviewed and all patients were contacted three months post-operatively to confirm whether they had experienced a dislocation. There were no dislocations in the less restricted group and one in the more restricted group (p = 0.32). For experienced surgeons using the posterolateral approach at THA and femoral heads of diameter ≥ 28 mm, it appears safe to manage patients in the immediate post-operative period with minimal precautions to protect against dislocation. Larger studies with adequate statistical power are needed to verify this conclusion. Experienced orthopaedic surgeons using the posterolateral approach for THA should not fear an increased dislocation rate if they manage their patients with a minimal precautions protocol. Cite this article: Bone Joint J 2016;98-B:589-94. ©2016 The British Editorial Society of Bone & Joint Surgery.

  18. Period-doubling reconstructions of semiconductor partial dislocations

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Park, Ji -Sang; Huang, Bing; Wei, Su -Huai

    2015-09-18

    Atomic-scale understanding and control of dislocation cores is of great technological importance, because they act as recombination centers for charge carriers in optoelectronic devices. Using hybrid density-functional calculations, we present period-doubling reconstructions of a 90 degrees partial dislocation in GaAs, for which the periodicity of like-atom dimers along the dislocation line varies from one to two, to four dimers. The electronic properties of a dislocation change drastically with each period doubling. The dimers in the single-period dislocation are able to interact, to form a dispersive one-dimensional band with deep-gap states. However, the inter-dimer interaction for the double-period dislocation becomes significantlymore » reduced; hence, it is free of mid-gap states. The Ga core undergoes a further period-doubling transition to a quadruple-period reconstruction induced by the formation of small hole polarons. In conclusion, the competition between these dislocation phases suggests a new passivation strategy via population manipulation of the detrimental single-period phase.« less

  19. Ultrasonic Study of Dislocation Dynamics in Lithium -

    NASA Astrophysics Data System (ADS)

    Han, Myeong-Deok

    1987-09-01

    Experimental studies of dislocation dynamics in LiF single crystals, using ultrasonic techniques combined with dynamic loading, were performed to investigate the time evolution of the plastic deformation process under a short stress pulse at room temperature, and the temperature dependence of the dislocation damping mechanism in the temperature range 25 - 300(DEGREES)K. From the former, the time dependence of the ultrasonic attenuation was understood as resulting from dislocation multiplication followed by the evolution of mobile dislocations to immobile ones under large stress. From the latter, the temperature dependence of the ultrasonic attenuation was interpreted as due to the motion of the dislocation loops overcoming the periodic Peierls potential barrier in a manner analogous to the motion of a thermalized sine-Gordon chain under a small stress. The Peierls stress obtained from the experimental results by application of Seeger's relaxation model with exponential dislocation length distribution was 4.26MPa, which is consistent with the lowest stress for the linear relation between the dislocation velocity and stress observed by Flinn and Tinder.

  20. Elasticity and dislocation anelasticity of crystals

    NASA Astrophysics Data System (ADS)

    Nikanorov, S. P.; Kardashev, B. K.

    The book is concerned with the application of the results of physical acoustic studies of elasticity and dislocation anelasticity to the investigation of interatomic interactions and interactions between lattice defects. The analysis of the potential functions determining the energy of interatomic interactions is based on a study of the elastic properties of crystals over a wide temperature range; data on the dislocation structure and on the interaction between dislocations and point defects are based mainly on a study of inelastic effects. Particular attention is given to the relationship between microplastic effects and the initial stage of plastic deformation under conditions of elastic oscillations, when the multiplication of dislocations is negligible.

  1. Modal analysis of dislocation vibration and reaction attempt frequency

    DOE PAGES

    Sobie, Cameron; Capolungo, Laurent; McDowell, David L.; ...

    2017-02-04

    Transition state theory is a fundamental approach for temporal coarse-graining. It estimates the reaction rate for a transition processes by quantifying the activation free energy and attempt frequency for the unit process. To calculate the transition rate of a gliding dislocation, the attempt frequency is often obtained from line tension estimates of dislocation vibrations, a highly simplified model of dislocation behavior. This work revisits the calculation of attempt frequency for a dislocation bypassing an obstacle, in this case a self-interstitial atom (SIA) loop. First, a direct calculation of the vibrational characteristics of a finite pinned dislocation segment is compared tomore » line tension estimates before moving to the more complex case of dislocation-obstacle bypass. The entropic factor associated with the attempt frequency is calculated for a finite dislocation segment and for an infinite glide dislocation interacting with an SIA loop. Lastly, it is found to be dislocation length independent for three cases of dislocation-self interstitial atom (SIA) loop interactions.« less

  2. Growth and dislocation studies of β-HMX.

    PubMed

    Gallagher, Hugh G; Sherwood, John N; Vrcelj, Ranko M

    2014-01-01

    The defect structure of organic materials is important as it plays a major role in their crystal growth properties. It also can play a subcritical role in "hot-spot" detonation processes of energetics and one such energetic is cyclotetramethylene-tetranitramine, in the commonly used beta form (β-HMX). The as-grown crystals grown by evaporation from acetone show prismatic, tabular and columnar habits, all with {011}, {110}, (010) and (101) faces. Etching on (010) surfaces revealed three different types of etch pits, two of which could be identified with either pure screw or pure edge dislocations, the third is shown to be an artifact of the twinning process that this material undergoes. Examination of the {011} and {110} surfaces show only one type of etch pit on each surface; however their natural asymmetry precludes the easy identification of their Burgers vector or dislocation type. Etching of cleaved {011} surfaces demonstrates that the etch pits can be associated with line dislocations. All dislocations appear randomly on the crystal surfaces and do not form alignments characteristic of mechanical deformation by dislocation slip. Crystals of β-HMX grown from acetone show good morphological agreement with that predicted by modelling, with three distinct crystal habits observed depending upon the supersaturation of the growth solution. Prismatic habit was favoured at low supersaturation, while tabular and columnar crystals were predominant at higher super saturations. The twin plane in β-HMX was identified as a (101) reflection plane. The low plasticity of β-HMX is shown by the lack of etch pit alignments corresponding to mechanically induced dislocation arrays. On untwinned {010} faces, two types of dislocations exist, pure edge dislocations with b = [010] and pure screw dislocations with b = [010]. On twinned (010) faces, a third dislocation type exists and it is proposed that these pits are associated with pure screw dislocations with b = [010

  3. Statistics of dislocation pinning at localized obstacles

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Dutta, A.; Bhattacharya, M., E-mail: mishreyee@vecc.gov.in; Barat, P.

    2014-10-14

    Pinning of dislocations at nanosized obstacles like precipitates, voids, and bubbles is a crucial mechanism in the context of phenomena like hardening and creep. The interaction between such an obstacle and a dislocation is often studied at fundamental level by means of analytical tools, atomistic simulations, and finite element methods. Nevertheless, the information extracted from such studies cannot be utilized to its maximum extent on account of insufficient information about the underlying statistics of this process comprising a large number of dislocations and obstacles in a system. Here, we propose a new statistical approach, where the statistics of pinning ofmore » dislocations by idealized spherical obstacles is explored by taking into account the generalized size-distribution of the obstacles along with the dislocation density within a three-dimensional framework. Starting with a minimal set of material parameters, the framework employs the method of geometrical statistics with a few simple assumptions compatible with the real physical scenario. The application of this approach, in combination with the knowledge of fundamental dislocation-obstacle interactions, has successfully been demonstrated for dislocation pinning at nanovoids in neutron irradiated type 316-stainless steel in regard to the non-conservative motion of dislocations. An interesting phenomenon of transition from rare pinning to multiple pinning regimes with increasing irradiation temperature is revealed.« less

  4. Dislocations and other topological oddities

    NASA Astrophysics Data System (ADS)

    Pieranski, Pawel

    2016-03-01

    We will show that the book Dislocations by Jacques Friedel, published half a century ago, can still be recommended, in agreement with the author's intention, as a textbook ;for research students at University and for students at engineering schools as well as for research engineers;. Indeed, today dislocations are known to occur not only in solid crystals but also in many other systems discovered more recently such as colloidal crystals or liquid crystals having periodic structures. Moreover, the concept of dislocations is an excellent starting point for lectures on topological defects occurring in systems equipped with order parameters resulting from broken symmetries: disclinations in nematic or hexatic liquid crystals, dispirations in chiral smectics or disorientations in lyotropic liquid crystals. The discussion of dislocations in Blue Phases will give us an opportunity to call on mind Sir Charles Frank, friend of Jacques Friedel since his Bristol years, who called these ephemeral mesophases ;topological oddities;. Being made of networks of disclinations, Blue Phases are similar to Twist Grain Boundary (TGB) smectic phases, which are made of networks of screw dislocations and whose existence was predicted by de Gennes in 1972 on the basis of the analogy between smectics and superconductors. We will stress that the book by Jacques Friedel contains seeds of this analogy.

  5. Closed reduction of displaced or dislocated mandibular condyle fractures in children using threaded Kirschner wire and external rubber traction.

    PubMed

    Kim, J H; Nam, D H

    2015-10-01

    Most surgeons agree that closed treatment provides the best results for condylar fractures in children. Nevertheless, treatment of the paediatric mandibular condyle fracture that is severely displaced or dislocated is controversial. The purpose of this study was to investigate the long-term clinical and radiological outcomes following the treatment of displaced or dislocated condylar fractures in children using threaded Kirschner wire and external rubber traction. This procedure can strengthen the advantage of closed reduction and make up for the shortcomings of open reduction. From March 1, 2005 to December 25, 2011, 11 children aged between 4 and 12 years with displaced or dislocated mandibular condyle fractures were treated using threaded Kirschner wire and external rubber traction under portable C-arm fluoroscopy. All patients had unilateral displaced or dislocated condylar fractures. The follow-up period ranged from 24 to 42 months (mean 29.3 months). Normal occlusion and pain-free function of the temporomandibular joint, without deviation or limitation of jaw opening, was achieved in all patients. This closed reduction technique in displaced or dislocated condylar fractures in children offers a reliable solution in preventing the unfavourable sequelae of closed treatment and the open technique, such as altered morphology, functional disturbances, and facial nerve damage. Copyright © 2015 International Association of Oral and Maxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved.

  6. Automated identification and indexing of dislocations in crystal interfaces

    DOE PAGES

    Stukowski, Alexander; Bulatov, Vasily V.; Arsenlis, Athanasios

    2012-10-31

    Here, we present a computational method for identifying partial and interfacial dislocations in atomistic models of crystals with defects. Our automated algorithm is based on a discrete Burgers circuit integral over the elastic displacement field and is not limited to specific lattices or dislocation types. Dislocations in grain boundaries and other interfaces are identified by mapping atomic bonds from the dislocated interface to an ideal template configuration of the coherent interface to reveal incompatible displacements induced by dislocations and to determine their Burgers vectors. Additionally, the algorithm generates a continuous line representation of each dislocation segment in the crystal andmore » also identifies dislocation junctions.« less

  7. Worker Dislocation and Its Consequences.

    ERIC Educational Resources Information Center

    Rosenbaum, Allan; Zirkin, Barbara G.

    A study examined the socioeconomic characteristcs, family and social supportive services, economic and social difficulties, education and training levels, and ways in which dislocated workers in Maryland found reemployment. Data were collected from in-depth personal interviews with 9 dislocated workers, questionnaires administered to 45 unemployed…

  8. Atomistic simulations of dislocation pileup: Grain boundaries interaction

    DOE PAGES

    Wang, Jian

    2015-05-27

    Here, using molecular dynamics (MD) simulations, we studied the dislocation pileup–grain boundary (GB) interactions. Two Σ11 asymmetrical tilt grain boundaries in Al are studied to explore the influence of orientation relationship and interface structure on dislocation activities at grain boundaries. To mimic the reality of a dislocation pileup in a coarse-grained polycrystalline, we optimized the dislocation population in MD simulations and developed a predict-correct method to create a dislocation pileup in MD simulations. MD simulations explored several kinetic processes of dislocations–GB reactions: grain boundary sliding, grain boundary migration, slip transmission, dislocation reflection, reconstruction of grain boundary, and the correlation ofmore » these kinetic processes with the available slip systems across the GB and atomic structures of the GB.« less

  9. Electron energy can oscillate near a crystal dislocation

    DOE PAGES

    Li, Mingda; Cui, Wenping; Dresselhaus, Mildred S.; ...

    2017-01-25

    Crystal dislocations govern the plastic mechanical properties of materials but also affect the electrical and optical properties. However, a fundamental and quantitative quantum field theory of a dislocation has remained undiscovered for decades. Here in this article we present an exactly-solvable one-dimensional quantum field theory of a dislocation, for both edge and screw dislocations in an isotropic medium, by introducing a new quasiparticle which we have called the ‘dislon’. The electron-dislocation relaxation time can then be studied directly from the electron self-energy calculation, which is reducible to classical results. In addition, we predict that the electron energy will experience anmore » oscillation pattern near a dislocation. Compared with the electron density’s Friedel oscillation, such an oscillation is intrinsically different since it exists even with only single electron is present. With our approach, the effect of dislocations on materials’ non-mechanical properties can be studied at a full quantum field theoretical level.« less

  10. A Novel Approach for Dynamic Testing of Total Hip Dislocation under Physiological Conditions.

    PubMed

    Herrmann, Sven; Kluess, Daniel; Kaehler, Michael; Grawe, Robert; Rachholz, Roman; Souffrant, Robert; Zierath, János; Bader, Rainer; Woernle, Christoph

    2015-01-01

    Constant high rates of dislocation-related complications of total hip replacements (THRs) show that contributing factors like implant position and design, soft tissue condition and dynamics of physiological motions have not yet been fully understood. As in vivo measurements of excessive motions are not possible due to ethical objections, a comprehensive approach is proposed which is capable of testing THR stability under dynamic, reproducible and physiological conditions. The approach is based on a hardware-in-the-loop (HiL) simulation where a robotic physical setup interacts with a computational musculoskeletal model based on inverse dynamics. A major objective of this work was the validation of the HiL test system against in vivo data derived from patients with instrumented THRs. Moreover, the impact of certain test conditions, such as joint lubrication, implant position, load level in terms of body mass and removal of muscle structures, was evaluated within several HiL simulations. The outcomes for a normal sitting down and standing up maneuver revealed good agreement in trend and magnitude compared with in vivo measured hip joint forces. For a deep maneuver with femoral adduction, lubrication was shown to cause less friction torques than under dry conditions. Similarly, it could be demonstrated that less cup anteversion and inclination lead to earlier impingement in flexion motion including pelvic tilt for selected combinations of cup and stem positions. Reducing body mass did not influence impingement-free range of motion and dislocation behavior; however, higher resisting torques were observed under higher loads. Muscle removal emulating a posterior surgical approach indicated alterations in THR loading and the instability process in contrast to a reference case with intact musculature. Based on the presented data, it can be concluded that the HiL test system is able to reproduce comparable joint dynamics as present in THR patients.

  11. A Novel Approach for Dynamic Testing of Total Hip Dislocation under Physiological Conditions

    PubMed Central

    Herrmann, Sven; Kluess, Daniel; Kaehler, Michael; Grawe, Robert; Rachholz, Roman; Souffrant, Robert; Zierath, János; Bader, Rainer; Woernle, Christoph

    2015-01-01

    Constant high rates of dislocation-related complications of total hip replacements (THRs) show that contributing factors like implant position and design, soft tissue condition and dynamics of physiological motions have not yet been fully understood. As in vivo measurements of excessive motions are not possible due to ethical objections, a comprehensive approach is proposed which is capable of testing THR stability under dynamic, reproducible and physiological conditions. The approach is based on a hardware-in-the-loop (HiL) simulation where a robotic physical setup interacts with a computational musculoskeletal model based on inverse dynamics. A major objective of this work was the validation of the HiL test system against in vivo data derived from patients with instrumented THRs. Moreover, the impact of certain test conditions, such as joint lubrication, implant position, load level in terms of body mass and removal of muscle structures, was evaluated within several HiL simulations. The outcomes for a normal sitting down and standing up maneuver revealed good agreement in trend and magnitude compared with in vivo measured hip joint forces. For a deep maneuver with femoral adduction, lubrication was shown to cause less friction torques than under dry conditions. Similarly, it could be demonstrated that less cup anteversion and inclination lead to earlier impingement in flexion motion including pelvic tilt for selected combinations of cup and stem positions. Reducing body mass did not influence impingement-free range of motion and dislocation behavior; however, higher resisting torques were observed under higher loads. Muscle removal emulating a posterior surgical approach indicated alterations in THR loading and the instability process in contrast to a reference case with intact musculature. Based on the presented data, it can be concluded that the HiL test system is able to reproduce comparable joint dynamics as present in THR patients. PMID:26717236

  12. Knee Dislocations in Sports Injuries

    PubMed Central

    Pardiwala, Dinshaw N; Rao, Nandan N; Anand, Karthik; Raut, Alhad

    2017-01-01

    Knee dislocations are devastating when they occur on the athletic field or secondary to motor sports. The complexity of presentation and spectrum of treatment options makes these injuries unique and extremely challenging to even the most experienced knee surgeons. An astute appreciation of the treatment algorithm is essential to plan individualized management since no two complex knee dislocations are ever the same. Moreover, attention to detail and finesse of surgical technique are required to obtain a good functional result and ensure return to play. Over the past 10 years, our service has treated 43 competitive sportsmen with knee dislocations, and this experience forms the basis for this narrative review. PMID:28966379

  13. Creep Deformation by Dislocation Movement in Waspaloy

    PubMed Central

    Whittaker, Mark; Harrison, Will; Deen, Christopher; Rae, Cathie; Williams, Steve

    2017-01-01

    Creep tests of the polycrystalline nickel alloy Waspaloy have been conducted at Swansea University, for varying stress conditions at 700 °C. Investigation through use of Transmission Electron Microscopy at Cambridge University has examined the dislocation networks formed under these conditions, with particular attention paid to comparing tests performed above and below the yield stress. This paper highlights how the dislocation structures vary throughout creep and proposes a dislocation mechanism theory for creep in Waspaloy. Activation energies are calculated through approaches developed in the use of the recently formulated Wilshire Equations, and are found to differ above and below the yield stress. Low activation energies are found to be related to dislocation interaction with γ′ precipitates below the yield stress. However, significantly increased dislocation densities at stresses above yield cause an increase in the activation energy values as forest hardening becomes the primary mechanism controlling dislocation movement. It is proposed that the activation energy change is related to the stress increment provided by work hardening, as can be observed from Ti, Ni and steel results. PMID:28772421

  14. Te homogeneous precipitation in Ge dislocation loop vicinity

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Perrin Toinin, J.; Portavoce, A., E-mail: alain.portavoce@im2np.fr; Texier, M.

    2016-06-06

    High resolution microscopies were used to study the interactions of Te atoms with Ge dislocation loops, after a standard n-type doping process in Ge. Te atoms neither segregate nor precipitate on dislocation loops, but form Te-Ge clusters at the same depth as dislocation loops, in contradiction with usual dopant behavior and thermodynamic expectations. Atomistic kinetic Monte Carlo simulations show that Te atoms are repulsed from dislocation loops due to elastic interactions, promoting homogeneous Te-Ge nucleation between dislocation loops. This phenomenon is enhanced by coulombic interactions between activated Te{sup 2+} or Te{sup 1+} ions.

  15. Joint correction of respiratory motion artifact and partial volume effect in lung/thoracic PET/CT imaging.

    PubMed

    Chang, Guoping; Chang, Tingting; Pan, Tinsu; Clark, John W; Mawlawi, Osama R

    2010-12-01

    Respiratory motion artifacts and partial volume effects (PVEs) are two degrading factors that affect the accuracy of image quantification in PET/CT imaging. In this article, the authors propose a joint motion and PVE correction approach (JMPC) to improve PET quantification by simultaneously correcting for respiratory motion artifacts and PVE in patients with lung/thoracic cancer. The objective of this article is to describe this approach and evaluate its performance using phantom and patient studies. The proposed joint correction approach incorporates a model of motion blurring, PVE, and object size/shape. A motion blurring kernel (MBK) is then estimated from the deconvolution of the joint model, while the activity concentration (AC) of the tumor is estimated from the normalization of the derived MBK. To evaluate the performance of this approach, two phantom studies and eight patient studies were performed. In the phantom studies, two motion waveforms-a linear sinusoidal and a circular motion-were used to control the motion of a sphere, while in the patient studies, all participants were instructed to breathe regularly. For the phantom studies, the resultant MBK was compared to the true MBK by measuring a correlation coefficient between the two kernels. The measured sphere AC derived from the proposed method was compared to the true AC as well as the ACs in images exhibiting PVE only and images exhibiting both PVE and motion blurring. For the patient studies, the resultant MBK was compared to the motion extent derived from a 4D-CT study, while the measured tumor AC was compared to the AC in images exhibiting both PVE and motion blurring. For the phantom studies, the estimated MBK approximated the true MBK with an average correlation coefficient of 0.91. The tumor ACs following the joint correction technique were similar to the true AC with an average difference of 2%. Furthermore, the tumor ACs on the PVE only images and images with both motion blur and PVE effects

  16. Dislocated Shoulder

    MedlinePlus

    ... up of three bones: your collarbone, your shoulder blade, and your upper arm bone. The top of ... fits into a cuplike socket in your shoulder blade. A shoulder dislocation is an injury that happens ...

  17. External fixation combined with delayed internal fixation in treatment of tibial plateau fractures with dislocation

    PubMed Central

    Tao, Xingguang; Chen, Nong; Pan, Fugen; Cheng, Biao

    2017-01-01

    Abstract The aim of this study was to evaluate the clinical efficacy of external fixation, delayed open reduction, and internal fixation in treating tibial plateau fracture with dislocation. Clinical data of 34 patients diagnosed with tibial plateau fracture complicated with dislocation between January 2009 and May 2015 were retrospectively analyzed. Fifteen patients in group A underwent early calcaneus traction combined with open reduction and internal fixation and 19 in group B received early external fixation combined with delayed open reduction and internal fixation. Operation time, postoperative complication, bone healing time, knee joint range of motion, initial weight-bearing time, Rasmussen tibial plateau score, and knee function score (HSS) were statistically compared between 2 groups. The mean follow-up time was 18.6 months (range: 5–24 months). The mean operation time in group A was 96 minutes, significantly longer than 71 minutes in group B (P < .05). In group A, 5 cases had postoperative complications and 1 in group B (P < .05). The mean bone healing time in group A was 6.9 months (range: 5–9 months) and 6.0 months (range: 5–8 months) in group B (P > .05). In group A, initial weight-bearing time in group A was (14.0 ± 3.6) weeks, significantly differing from (12.9 ± 2.8) weeks in group B (P < 0.05). In group A, the mean knee joint range of motion was 122° (range: 95°–150°) and 135° (range: 100°–160°) in group B (P > 0.05). Rasmussen tibial plateau score in group A was slightly lower than that in group B (P > .05). The excellent rate of knee joint function in group A was 80% and 84.21% in group B (P > .05). External fixation combined with delayed open reduction and internal fixation is a safer and more efficacious therapy of tibial plateau fracture complicated with dislocation compared with early calcaneus traction and open reduction and internal fixation. PMID:29019890

  18. Accuracy of in vivo palpation-guided acromioclavicular joint injection assessed with contrast material and fluoroscopic evaluations.

    PubMed

    Scillia, Anthony; Issa, Kimona; McInerney, Vincent K; Milman, Edward; Baltazar, Romulo; Dasti, Umer; Festa, Anthony

    2015-08-01

    The purpose of this study was to evaluate the accuracy of in vivo acromioclavicular (AC) joint injections without fluoroscopic guidance and assess whether patient demographics affected the accuracy of injections. A consecutive cohort of patients who presented with painful acromioclavicular joints was prospectively evaluated. All patients had clinical and radiographic evidence of AC arthritis, had failed conservative measures, and thus had received intraarticular corticosteroid injections. All injections were performed by experienced fellowship-trained musculoskeletal radiologists and by blinded digital palpation technique. Accuracy of injections was assessed with biplanar fluoroscopic views. Forty-one AC injections in 22 males and 16 females with a mean age of 51 years (range 18 to 78) were identified. Twenty-three injections were in the right shoulder and 18 in the left. Only 15 injections were confirmed to be in the intraarticular AC joint, yielding an accuracy of 36.5%. There were no significant differences in the mean age (54 vs. 52 years; p = 0.58), male-to-female ratio (p = 0.73), and side of the injection between the accurate and inaccurate injections, respectively. Based on the findings of the present study, the authors encourage the use of image guidance for corticosteroid treatment of the AC joint. Level IV Therapeutic Case Series.

  19. 3D discrete dislocation dynamics study of creep behavior in Ni-base single crystal superalloys by a combined dislocation climb and vacancy diffusion model

    NASA Astrophysics Data System (ADS)

    Gao, Siwen; Fivel, Marc; Ma, Anxin; Hartmaier, Alexander

    2017-05-01

    A three-dimensional (3D) discrete dislocation dynamics (DDD) creep model is developed to investigate creep behavior under uniaxial tensile stress along the crystallographic [001] direction in Ni-base single crystal superalloys, which takes explicitly account of dislocation glide, climb and vacancy diffusion, but neglects phase transformation like rafting of γ‧ precipitates. The vacancy diffusion model takes internal stresses by dislocations and mismatch strains into account and it is coupled to the dislocation dynamics model in a numerically efficient way. This model is helpful for understanding the fundamental creep mechanisms in superalloys and clarifying the effects of dislocation glide and climb on creep deformation. In cases where the precipitate cutting rarely occurs, e.g. due to the high anti-phase boundary energy and the lack of superdislocations, the dislocation glide in the γ matrix and the dislocation climb along the γ/γ‧ interface dominate plastic deformation. The simulation results show that a high temperature or a high stress both promote dislocation motion and multiplication, so as to cause a large creep strain. Dislocation climb accelerated by high temperature only produces a small plastic strain, but relaxes the hardening caused by the filling γ channels and lets dislocations further glide and multiply. The strongest variation of vacancy concentration occurs in the horizontal channels, where more mixed dislocations exit and tend to climb. The increasing internal stresses due to the increasing dislocation density are easily overcome by dislocations under a high external stress that leads to a long-term dislocation glide accompanied by multiplication.

  20. Arthroscopic findings after shoulder dislocation.

    PubMed

    Hintermann, B; Gächter, A

    1995-01-01

    The purpose of this study was to evaluate prospectively the arthroscopic findings of the unstable shoulder, to provide insights into the causes and mechanisms of shoulder instability, and to establish a rationale for using special surgical procedures. Arthroscopic examination was performed on 212 patients who had at least 1 documented shoulder dislocation. Of these 212 patients, 184 (87%) patients had anterior glenoid labral tears, 168 (79%) patients had ventral capsule insufficiency, 144 (68%) patients had Hill-Sachs compression fractures, 116 (55%) patients had glenohumeral ligament insufficiency, 30 (14%) patients had complete rotator cuff tendon tears, 26 (12%) patients had posterior glenoid labral tears, 14 (7%) patients had superior labrum anterior and inferior lesions. As this prospective study shows, multiple morphologic changes are associated with instability of the glenohumeral joint; there is no single cause for an unstable shoulder. Arthroscopic examination of the shoulder before surgery revealed a significant amount of information that would have been undetected without the aid of expensive diagnostic tools. For instance, the labrum and rim of the anteroinferior glenoid showed typical abnormalities corresponding to different entities of anterior instability.

  1. Dislocation nucleation facilitated by atomic segregation

    NASA Astrophysics Data System (ADS)

    Zou, Lianfeng; Yang, Chaoming; Lei, Yinkai; Zakharov, Dmitri; Wiezorek, Jörg M. K.; Su, Dong; Yin, Qiyue; Li, Jonathan; Liu, Zhenyu; Stach, Eric A.; Yang, Judith C.; Qi, Liang; Wang, Guofeng; Zhou, Guangwen

    2018-01-01

    Surface segregation--the enrichment of one element at the surface, relative to the bulk--is ubiquitous to multi-component materials. Using the example of a Cu-Au solid solution, we demonstrate that compositional variations induced by surface segregation are accompanied by misfit strain and the formation of dislocations in the subsurface region via a surface diffusion and trapping process. The resulting chemically ordered surface regions acts as an effective barrier that inhibits subsequent dislocation annihilation at free surfaces. Using dynamic, atomic-scale resolution electron microscopy observations and theory modelling, we show that the dislocations are highly active, and we delineate the specific atomic-scale mechanisms associated with their nucleation, glide, climb, and annihilation at elevated temperatures. These observations provide mechanistic detail of how dislocations nucleate and migrate at heterointerfaces in dissimilar-material systems.

  2. BBilateral Neglected Anterior Shoulder Dislocation with Greater Tuberosity Fractures

    PubMed Central

    Upasani, Tejas; Bhatnagar, Abhinav; Mehta, Sonu

    2016-01-01

    Introduction: Shoulder dislocations are a very common entity in routine orthopaedic practice. Chronic unreduced anterior dislocations of the shoulder are not very common. Neurological and vascular complications may occur as a result of an acute anterior dislocation of the shoulder or after a while in chronic unreduced shoulder dislocation. Open reduction is indicated for most chronic shoulder dislocations. We report a case of neglected bilateral anterior shoulder dislocation with bilateral displaced greater tuberosity fracture. To the best of our knowledge, only a handful cases have been reported in literature with bilateral anterior shoulder dislocation with bilateral fractures. Delayed diagnosis/reporting is a scenario which makes the list even slimmer and management all the more challenging. Case Report: We report a case of a 35-year-old male who had bilateral anterior shoulder dislocation and bilateral greater tuberosity fracture post seizure and failed to report it for a period of 30 days. One side was managed conservatively with closed reduction and immobilization and the other side with open reduction. No neurovascular complications pre or post reduction of shoulder were seen. Conclusion: Shoulder dislocations should always be suspected post seizures and if found should be treated promptly. Treatment becomes difficult for any shoulder dislocation that goes untreated for considerable period of time PMID:27703939

  3. Treatment of recurrent patellar dislocation via knee arthroscopy combined with C-arm fluoroscopy and reconstruction of the medial patellofemoral ligament.

    PubMed

    Li, Li; Wang, Hongbo; He, Yun; Si, Yu; Zhou, Hongyu; Wang, Xin

    2018-06-01

    Recurrent patellar dislocations were treated via knee arthroscopy combined with C-arm fluoroscopy, and reconstruction of the medial patellofemoral ligaments. Between October 2013 and March 2017, 52 cases of recurrent patellar dislocation [27 males and 25 females; age, 16-47 years (mean, 21.90 years)] were treated. Arthroscopic exploration was performed and patellofemoral joint cartilage injuries were repaired. It was subsequently determined whether it was necessary to release the lateral patellofemoral support belt. Pre-operative measurements were used to decide whether tibial tubercle osteotomy was required. Medial patellofemoral ligaments were reconstructed using autologous semitendinosus tendons. Smith and Nephew model 3.5 line anchors were used to double-anchor the medial patellofemoral margin. On the femoral side, the medial patellofemoral ligament was fixed using 7-cm, absorbable, interfacial compression screws. All cases were followed for 1-40 months (average, 21 months). The Q angle, tibial tuberosity trochlear groove distance, Insall-Salvati index, patellofemoral angle, lateral patellofemoral angle and lateral shift were evaluated on X-Ray images using the picture archiving and communication system. Subjective International Knee Documentation Committee (IKDC) knee joint functional scores and Lysholm scores were recorded. Post-operative fear was absent, and no patellar re-dislocation or re-fracture was noted during follow-up. At the end of follow-up, the patellofemoral angle (0.22±4.23°), lateral patellofemoral angle (3.44±1.30°), and lateral shift (0.36+0.14°) differed significantly from the pre-operative values (all, P<0.05). Furthermore, IKDC and Lysholm scores (87.84+3.74 and 87.48+3.35, respectively) differed significantly from the pre-operative values (both, P<0.05). These findings suggest that, in the short term, recurrent patellar dislocation treatment via knee arthroscopy combined with C-arm fluoroscopy and reconstruction of the medial

  4. Unravelling the physics of size-dependent dislocation-mediated plasticity

    NASA Astrophysics Data System (ADS)

    El-Awady, Jaafar A.

    2015-01-01

    Size-affected dislocation-mediated plasticity is important in a wide range of materials and technologies. Here we develop a generalized size-dependent dislocation-based model that predicts strength as a function of crystal/grain size and the dislocation density. Three-dimensional (3D) discrete dislocation dynamics (DDD) simulations reveal the existence of a well-defined relationship between strength and dislocation microstructure at all length scales for both single crystals and polycrystalline materials. The results predict a transition from dislocation-source strengthening to forest-dominated strengthening at a size-dependent critical dislocation density. It is also shown that the Hall-Petch relationship can be physically interpreted by coupling with an appropriate kinetic equation of the evolution of the dislocation density in polycrystals. The model is shown to be in remarkable agreement with experiments. This work presents a micro-mechanistic framework to predict and interpret strength size-scale effects, and provides an avenue towards performing multiscale simulations without ad hoc assumptions.

  5. Truly anatomic coracoclavicular ligament reconstruction with 2 Endobutton devices for acute Rockwood type V acromioclavicular joint dislocations.

    PubMed

    Xue, Cheng; Song, Li-Jun; Zhang, Hao; Tang, Guo-Long; Li, Xiang; Fang, Jia-Hu

    2018-06-01

    Truly anatomic coracoclavicular ligament reconstruction (TACCR) according to the original insertions is a creative new method for the treatment of severe acromioclavicular separation. This research analyzed the clinical and radiologic results of TACCR in 25 patients with at least 2-year follow-up. The study enrolled 25 patients with Rockwood type V acromioclavicular joint dislocations who underwent TACCR using 2 Endobutton (Smith & Nephew Inc., Andover, MA, USA) devices from May 2013 to October 2015. Patients were assessed with clinical and radiologic follow-up at 3, 6, 12, 18, and 24 months postoperatively. The clinical assessments consisted of the visual analog scale and the Constant score. The radiographic evaluations were performed by measurements of the coracoclavicular distance. The mean follow-up was 34 ± 6.8 months (range, 24-48 months). The visual analog scale and Constant scores revealed significant advancements from 5 ± 0.9 (range, 4-7) and 45 ± 5.6 (range, 30-54) scores preoperatively to 0 ± 0.5 (range, 0-2) and 95 ± 2.9 (range, 91-98) scores at 24 months postoperatively, respectively. The coracoclavicular distance significantly decreased from 23 ± 5.4 mm (range, 16-34 mm) preoperatively to 8 ± 0.9 mm (range, 7-10 mm) at the final follow-up. TACCR represents a safe, reliable and creative surgical technique that yields good to excellent clinical and radiologic outcomes in the treatment of severe acromioclavicular separation. Copyright © 2017 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Elsevier Inc. All rights reserved.

  6. What are the risk factors for dislocation in primary total hip arthroplasty? A multicenter case-control study of 128 unstable and 438 stable hips.

    PubMed

    Fessy, M H; Putman, S; Viste, A; Isida, R; Ramdane, N; Ferreira, A; Leglise, A; Rubens-Duval, B; Bonin, N; Bonnomet, F; Combes, A; Boisgard, S; Mainard, D; Leclercq, S; Migaud, H

    2017-09-01

    an OR of 3.9 (95% CI: 2.15-7.1), history of spinal disease (lumbar stenosis, spinal fusion, discectomy, scoliosis and injury sequelae) with an OR of 1.89 (95% CI: 1.0-3.6), unrepaired joint capsule (all approaches) with an OR of 4.1 (95% CI: 2.3-7.37), unrepaired joint capsule (posterior approach) with an OR of 6.0 (95% CI: 2.2-15.9), and cup inclination outside Lewinnek's safe zone (30°-50°) with OR of 2.4 (95% CI: 1.4-4.0). This large comparative study isolated important patient-related factors for dislocation that surgeons must be aware of. We also found evidence that implanting the cup in 30° to 50° inclination has a major impact on preventing dislocation. Level III; case-control study. Copyright © 2017 Elsevier Masson SAS. All rights reserved.

  7. Distraction, Compression, Extension, and Reduction Combined With Joint Remodeling and Extra-articular Distraction: Description of 2 New Modifications for Its Application in Basilar Invagination and Atlantoaxial Dislocation: Prospective Study in 79 Cases.

    PubMed

    Chandra, P Sarat; Prabhu, Manik; Goyal, Nishant; Garg, Ajay; Chauhan, Avnish; Sharma, Bhawani Shankar

    2015-07-01

    Recent strategies for treatment of basilar invagination (BI) and atlantoaxial dislocation (AAD) are based on simultaneous posterior reduction and fixation. To describe new modifications of the procedure distraction, compression, extension, and reduction (DCER), ie, joint remodeling (JRM) and extra-articular distraction (EAD) in patients with "vertical" joints, and to quantify the improvement in joint indices, ie, sagittal inclination (SI), craniocervical tilt (CCT), and coronal inclination. Prospective study (May 2010 to September 2014). Joint indices measured included (normal values): SI (87.15 ± 5.65°), CCT (60.2 ± 9.2°), and coronal inclination (110.3 ± 4.23°). Surgical procedures included DCER alone (performed in SI <100°, group I) or JRM with DCER (in SI: 100-160°, group II), or EAD with DCER in severe BI with almost vertical joints (SI >160°, group III). Seventy-nine patients were selected (mean, 22.5 years of age). All conventional indices improved significantly (P < .001). CCT improved in all groups (P < .01); group I (n = 32): 54 ± 8.7° (preoperative 80.71 ± 12.72°); group II (n = 40): 58 ± 7.0° (preoperative 86.5 ± 14°); group III (n = 7): 62 ± 10.0° (preoperative 104 ± 11.2°). SI improved in both group I and II, P < .01 (cannot be measured in group III). At long-term follow-up (n = 64, 29 ± 8 months, range 12-39 months), the Nurick grade improved to 1.5 ± 0.52 (preoperative: 3.4 ± 0.65; P < .001). DCER seems to be an effective technique in reducing both BI and AAD. JRM and EAD with DCER are useful in moderate to severe BI and AAD (with SI >100°). Joint indices provide useful information for surgical strategy and planning.

  8. [Traumatic knee dislocation with popliteal vascular disruption: retrospective study of 14 cases].

    PubMed

    Bonnevialle, P; Chaufour, X; Loustau, O; Mansat, P; Pidhorz, L; Mansat, M

    2006-12-01

    Complex femorotibial dislocation of the knee joint generally results from high-energy trauma caused by a traffic or a contact sport accident. Besides disruption of the cruciate ligaments, in 10-25% of patients present concomitant palsy of the common peroneal nerve and more rarely disruption of the popliteal artery. The purpose of this work was to assess outcome in a monocentric consecutive series of knee dislocations with ischemia due to disruption of the popliteal artery and to focus on specific aspects of management. This retrospective series included eleven men and three women, aged 18 to 74 years (mean 47 years). The right knee was injured in five and the left knee in six. Trauma resulted from a farm accident in six patients, fall from a high level in two, a traffic accident in three and a skiing accident (fall) in one. Two other patients with morbid obesity were fall victims. Nine patients had a single injury, two presented an associated serious head injury, one a severe chest injury, and one multiple trauma with coma, chest contusion, and abdominal lesions. One patient had a fracture of the distal femur with associated ischemia. Five knee dislocations were open with a popliteal wound for three and a posteromedial wound for two. Four patients presented total sciatic nerve palsy and nine palsy of the common peroneal nerve. The dislocation was documented in ten cases: lateral (n=1), anterior (n=4), posterior (n=5). For four patients, the dislocation had been reduced during pre-hospital care. Preoperative arteriography was available for eight patients and confirmed the disruption of the popliteal artery; the diagnosis was obvious in six other patients who were directed immediately to the operative theatre without pre-operative imaging. Revascularization was achieved with a upper popliteal-lower popliteal bypass using an inverted saphenous graft. The graft was harvested from the homolateral greater saphenous vein in eight patients and the contralateral vein in six

  9. Atlanto-occipital dislocation: Case report and discussion.

    PubMed

    Asfaw, Tehetena; Chow, Bernard; Frederiksen, Ryan A

    2011-01-01

    Traumatic atlanto-occipital dislocation is an uncommon injury that frequently results in either a fatal outcome or severe neurologic deficit. This diagnosis must be considered for any patients who may have had cervical spine damage after high trauma, even in the absence of neurologic signs, as there have been reports of cases without neurologic impairment. In addition to radiographic examination, including lateral cervical radiographs, supplemental imaging with CT or MRI may be required to confirm diagnosis in equivocal cases, and to help in evaluation of bone and nervous structures. Moreover, these modalities allow measurement of the magnitude of dislocation and aid in classification of type of dislocation, which helps guide management. A systematic approach to evaluating the cranio-cervical relationship is critical to identifying atlanto-occipital dislocation. This case report presents and discusses imaging findings that will assist in the diagnosis of atlanto-occipital dislocation.

  10. Kneecap dislocation

    MedlinePlus

    ... dislocates to the outside of the knee Knee pain and tenderness Knee swelling "Sloppy" kneecap -- you can move the kneecap ... knee and you notice: Increased instability in your knee Pain or swelling return after they went away Your ...

  11. Hydrogenated vacancies lock dislocations in aluminium

    PubMed Central

    Xie, Degang; Li, Suzhi; Li, Meng; Wang, Zhangjie; Gumbsch, Peter; Sun, Jun; Ma, Evan; Li, Ju; Shan, Zhiwei

    2016-01-01

    Due to its high diffusivity, hydrogen is often considered a weak inhibitor or even a promoter of dislocation movements in metals and alloys. By quantitative mechanical tests in an environmental transmission electron microscope, here we demonstrate that after exposing aluminium to hydrogen, mobile dislocations can lose mobility, with activating stress more than doubled. On degassing, the locked dislocations can be reactivated under cyclic loading to move in a stick-slip manner. However, relocking the dislocations thereafter requires a surprisingly long waiting time of ∼103 s, much longer than that expected from hydrogen interstitial diffusion. Both the observed slow relocking and strong locking strength can be attributed to superabundant hydrogenated vacancies, verified by our atomistic calculations. Vacancies therefore could be a key plastic flow localization agent as well as damage agent in hydrogen environment. PMID:27808099

  12. Hydrogenated vacancies lock dislocations in aluminium

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Xie, Degang; Li, Suzhi; Li, Meng

    Due to its high diffusivity, hydrogen is often considered a weak inhibitor or even a promoter of dislocation movements in metals and alloys. By quantitative mechanical tests in an environmental transmission electron microscope, here we demonstrate that after exposing aluminium to hydrogen, mobile dislocations can lose mobility, with activating stress more than doubled. On degassing, the locked dislocations can be reactivated under cyclic loading to move in a stick-slip manner. However, relocking the dislocations thereafter requires a surprisingly long waiting time of ~10 3 s, much longer than that expected from hydrogen interstitial diffusion. Both the observed slow relocking andmore » strong locking strength can be attributed to superabundant hydrogenated vacancies, verified by our atomistic calculations. In conclusion, vacancies therefore could be a key plastic flow localization agent as well as damage agent in hydrogen environment.« less

  13. Hydrogenated vacancies lock dislocations in aluminium

    DOE PAGES

    Xie, Degang; Li, Suzhi; Li, Meng; ...

    2016-11-03

    Due to its high diffusivity, hydrogen is often considered a weak inhibitor or even a promoter of dislocation movements in metals and alloys. By quantitative mechanical tests in an environmental transmission electron microscope, here we demonstrate that after exposing aluminium to hydrogen, mobile dislocations can lose mobility, with activating stress more than doubled. On degassing, the locked dislocations can be reactivated under cyclic loading to move in a stick-slip manner. However, relocking the dislocations thereafter requires a surprisingly long waiting time of ~10 3 s, much longer than that expected from hydrogen interstitial diffusion. Both the observed slow relocking andmore » strong locking strength can be attributed to superabundant hydrogenated vacancies, verified by our atomistic calculations. In conclusion, vacancies therefore could be a key plastic flow localization agent as well as damage agent in hydrogen environment.« less

  14. Biomechanical Comparison of an Intramedullary and Extramedullary Free-Tissue Graft Reconstruction of the Acromioclavicular Joint Complex

    PubMed Central

    Garg, Rishi; Javidan, Pooya; Lee, Thay Q.

    2013-01-01

    Background Several different surgical techniques have been described to address the coracoclavicular (CC) ligaments in acromioclavicular (AC) joint injuries. However, very few techniques focus on reconstructing the AC ligaments, despite its importance in providing stability. The purpose of our study was to compare the biomechanical properties of two free-tissue graft techniques that reconstruct both the AC and CC ligaments in cadaveric shoulders, one with an extramedullary AC reconstruction and the other with an intramedullary AC reconstruction. We hypothesized intramedullary AC reconstruction will provide greater anteroposterior translational stability and improved load to failure characteristics than an extramedullary technique. Methods Six matched cadaveric shoulders underwent translational testing at 10 N and 15 N in the anteroposterior and superoinferior directions, under AC joint compression loads of 10 N, 20 N, and 30 N. After the AC and CC ligaments were transected, one of the specimens was randomly assigned the intramedullary free-tissue graft reconstruction while its matched pair received the extramedullary graft reconstruction. Both reconstructed specimens then underwent repeat translational testing, followed by load to failure testing, via superior clavicle distraction, at a rate of 50 mm/min. Results Intramedullary reconstruction provided significantly greater translational stability in the anteroposterior direction than the extramedullary technique for four of six loading conditions (p < 0.05). There were no significant differences in translational stability in the superoinferior direction for any loading condition. The intramedullary reconstructed specimens demonstrated improved load to failure characteristics with the intramedullary reconstruction having a lower deformation at yield and a higher ultimate load than the extramedullary reconstruction (p < 0.05). Conclusions Intramedullary reconstruction of the AC joint provides greater stability in the

  15. Peierls-Nabarro modeling of dislocations in UO2

    NASA Astrophysics Data System (ADS)

    Skelton, Richard; Walker, Andrew M.

    2017-11-01

    Under conditions of high stress or low temperature, glide of dislocations plays an important role in the deformation of UO2. In this paper, the Peierls-Nabarro model is used to calculate the core widths and Peierls stresses of ½<110> edge and screw dislocations gliding on {100}, {110}, and {111}. The energy of the inelastic displacement field in the dislocation core is parameterized using generalized stacking fault energies, which are calculated atomistically using interatomic potentials. We use seven different interatomic potential models, representing the variety of different models available for UO2. The different models broadly agree on the relative order of the strengths of the different slip systems, with the 1/2<110>{100} edge dislocation predicted to be the weakest slip system and 1/2<110>{110} the strongest. However, the calculated Peierls stresses depend strongly on the interatomic potential used, with values ranging between 2.7 and 12.9 GPa for glide of 1/2<110>{100} edge dislocations, 16.4-32.3 GPa for 1/2<110>{110} edge dislocations, and 6.8-13.6 GPa for 1/2<110>{111} edge dislocations. The glide of 1/2<110> screw dislocations in UO2 is also found to depend on the interatomic potential used, with some models predicting similar Peierls stresses for glide on {100} and {111}, while others predict a unique easy glide direction. Comparison with previous fully atomistic calculations show that the Peierls-Nabarro model can accurately predict dislocation properties in UO2.

  16. Surface dislocation nucleation controlled deformation of Au nanowires

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Roos, B.; Kapelle, B.; Volkert, C. A., E-mail: volkert@ump.gwdg.de

    2014-11-17

    We investigate deformation in high quality Au nanowires under both tension and bending using in-situ transmission electron microscopy. Defect evolution is investigated during: (1) tensile deformation of 〈110〉 oriented, initially defect-free, single crystal nanowires with cross-sectional widths between 30 and 300 nm, (2) bending deformation of the same wires, and (3) tensile deformation of wires containing coherent twin boundaries along their lengths. We observe the formation of twins and stacking faults in the single crystal wires under tension, and storage of full dislocations after bending of single crystal wires and after tension of twinned wires. The stress state dependence of themore » deformation morphology and the formation of stacking faults and twins are not features of bulk Au, where deformation is controlled by dislocation interactions. Instead, we attribute the deformation morphologies to the surface nucleation of either leading or trailing partial dislocations, depending on the Schmid factors, which move through and exit the wires producing stacking faults or full dislocation slip. The presence of obstacles such as neutral planes or twin boundaries hinder the egress of the freshly nucleated dislocations and allow trailing and leading partial dislocations to combine and to be stored as full dislocations in the wires. We infer that the twins and stacking faults often observed in nanoscale Au specimens are not a direct size effect but the result of a size and obstacle dependent transition from dislocation interaction controlled to dislocation nucleation controlled deformation.« less

  17. Dynamics of threading dislocations in porous heteroepitaxial GaN films

    NASA Astrophysics Data System (ADS)

    Gutkin, M. Yu.; Rzhavtsev, E. A.

    2017-12-01

    Behavior of threading dislocations in porous heteroepitaxial gallium nitride (GaN) films has been studied using computer simulation by the two-dimensional discrete dislocation dynamics approach. A computational scheme, where pores are modeled as cross sections of cylindrical cavities, elastically interacting with unidirectional parallel edge dislocations, which imitate threading dislocations, is used. Time dependences of coordinates and velocities of each dislocation from dislocation ensembles under investigation are obtained. Visualization of current structure of dislocation ensemble is performed in the form of a location map of dislocations at any time. It has been shown that the density of appearing dislocation structures significantly depends on the ratio of area of a pore cross section to area of the simulation region. In particular, increasing the portion of pores surface on the layer surface up to 2% should lead to about a 1.5-times decrease of the final density of threading dislocations, and increase of this portion up to 15% should lead to approximately a 4.5-times decrease of it.

  18. Hydrogen diffusion in the elastic fields of dislocations in iron

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Sivak, A. B., E-mail: Sivak-AB@nrcki.ru; Sivak, P. A.; Romanov, V. A.

    2016-12-15

    The effect of dislocation stress fields on the sink efficiency thereof is studied for hydrogen interstitial atoms at temperatures of 293 and 600 K and at a dislocation density of 3 × 10{sup 14} m{sup –2} in bcc iron crystal. Rectilinear full screw and edge dislocations in basic slip systems 〈111〉(110), 〈111〉(112), 〈100〉(100), and 〈100〉(110) are considered. Diffusion of defects is simulated by means of the object kinetic Monte Carlo method. The energy of interaction between defects and dislocations is calculated using the anisotropic theory of elasticity. The elastic fields of dislocations result in a less than 25% change ofmore » the sink efficiency as compared to the noninteracting linear sink efficiency at a room temperature. The elastic fields of edge dislocations increase the dislocation sink efficiency, whereas the elastic fields of screw dislocations either decrease this parameter (in the case of dislocations with the Burgers vector being 1/2〈111〉) or do not affect it (in the case of dislocations with the Burgers vector being 〈100〉). At temperatures above 600 K, the dislocations affect the behavior of hydrogen in bcc iron mainly owing to a high binding energy between the hydrogen atom and dislocation cores.« less

  19. The treatment of an osteochondral shearing fracture-dislocation of the head of the proximal phalanx: a case report.

    PubMed

    Harness, Neil; Jupiter, Jesse B

    2004-09-01

    We report the morphology and treatment of a proximal interphalangeal joint dislocation resulting in an injury to the articular surface of the proximal phalanx and avulsion of the radial collateral ligament from its proximal origin. A large osteochondral fragment was sheared from the radial articular surface of the proximal phalanx and remained displaced volarly after reduction of the joint. Plain radiographs and 2- and 3-dimensional computed tomography images were used to evaluate this unusual injury before surgery. Open reduction and internal fixation using a small K-wire and figure-of-eight wire technique restored the articular surface of the head of the proximal phalanx and gave a satisfactory functional result.

  20. Dislocation structure produced by an ultrashort shock pulse

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Matsuda, Tomoki, E-mail: t-matsu@mapse.eng.osaka-u.ac.jp; Hirose, Akio; Sano, Tomokazu

    We found an ultrashort shock pulse driven by a femtosecond laser pulse on iron generates a different dislocation structure than the shock process which is on the nanosecond timescale. The ultrashort shock pulse produces a highly dense dislocation structure that varies by depth. According to transmission electron microscopy, dislocations away from the surface produce microbands via a network structure similar to a long shock process, but unlike a long shock process dislocations near the surface have limited intersections. Considering the dislocation motion during the shock process, the structure near the surface is attributed to the ultrashort shock duration. This approachmore » using an ultrashort shock pulse will lead to understanding the whole process off shock deformation by clarifying the early stage.« less

  1. Dislocation filtering in GaN nanostructures.

    PubMed

    Colby, Robert; Liang, Zhiwen; Wildeson, Isaac H; Ewoldt, David A; Sands, Timothy D; García, R Edwin; Stach, Eric A

    2010-05-12

    Dislocation filtering in GaN by selective area growth through a nanoporous template is examined both by transmission electron microscopy and numerical modeling. These nanorods grow epitaxially from the (0001)-oriented GaN underlayer through the approximately 100 nm thick template and naturally terminate with hexagonal pyramid-shaped caps. It is demonstrated that for a certain window of geometric parameters a threading dislocation growing within a GaN nanorod is likely to be excluded by the strong image forces of the nearby free surfaces. Approximately 3000 nanorods were examined in cross-section, including growth through 50 and 80 nm diameter pores. The very few threading dislocations not filtered by the template turn toward a free surface within the nanorod, exiting less than 50 nm past the base of the template. The potential active region for light-emitting diode devices based on these nanorods would have been entirely free of threading dislocations for all samples examined. A greater than 2 orders of magnitude reduction in threading dislocation density can be surmised from a data set of this size. A finite element-based implementation of the eigenstrain model was employed to corroborate the experimentally observed data and examine a larger range of potential nanorod geometries, providing a simple map of the different regimes of dislocation filtering for this class of GaN nanorods. These results indicate that nanostructured semiconductor materials are effective at eliminating deleterious extended defects, as necessary to enhance the optoelectronic performance and device lifetimes compared to conventional planar heterostructures.

  2. Dislocation evolution in 316 L stainless steel during multiaxial ratchetting deformation

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Dong Yawei; Kang Guozheng, E-mail: guozhengkang@yahoo.com.cn; Liu Yujie

    2012-03-15

    Dislocation patterns and their evolutions in 316 L stainless steel during the multiaxial ratchetting deformation were observed by transmission electron microscopy (TEM). The microscopic observations indicate that the dislocation evolution presented during the multiaxial ratchetting with four kinds of multiaxial loading paths is similar to that in the uniaxial case [G. Z. Kang et al., Mater Sci Eng A 527 (2010) 5952]. That is, dislocation networks and dislocation tangles are formed quickly by the multiple-slip and cross-slip of dislocation activated by applied multiaxial stress; and then polarized patterns such as dislocation walls and elongated incipient dislocation cells are formed atmore » the last stage of multiaxial ratchetting. The dislocation patterns evolve more quickly from the modes at low dislocation density to the ones at high density during the multiaxial ratchetting than that in the uniaxial case, and some traces of multiple-slip are observed in the multiaxial ones. The dislocation evolution during the multiaxial ratchetting deformation is summarized by comparing the observed dislocation patterns with those presented in the multiaxial strain-controlled and symmetrical stress-controlled cyclic tests. The multiaxial ratchetting of 316 L stainless steel can be microscopically and qualitatively explained by the observed evolution of dislocation patterns. - Highlights: Black-Right-Pointing-Pointer Dislocation patterns change from lines and nets to tangles, walls and cells. Black-Right-Pointing-Pointer Dislocation patterns evolve quicker in the multiaxial case. Black-Right-Pointing-Pointer Aligned dislocation arrays and some traces of multiple slips are observed. Black-Right-Pointing-Pointer Heterogeneous dislocation patterns result in the multiaxial ratchetting.« less

  3. Charcot joint-like changes following ankle fracture in a patient with no underlying disease: report of a rare case.

    PubMed

    Kumagai, Masaru; Yokota, Kiyoshi; Endoh, Toshiya; Takemoto, Hitoshi; Nagata, Kensei

    2002-01-01

    Charcot joint is a disease that often occurs in patients with diabetes mellitus, tabes dorsalis, syringomyelia, chronic alcoholism, leprosy, trauma, or infection after fractures and dislocations. The treatment for Charcot joint has various complications, such as skin lesions, infections, and delayed union. We present our experience with a male patient who developed Charcot joint-like changes without diabetes mellitus or any other disease after an ankle fracture due to minor trauma.

  4. A Rare Case of Massive Rotator Cuff Tear and Biceps Tendon Rupture with Posterior Shoulder Dislocation in a Young Adult - Surgical Decision-making and Outcome

    PubMed Central

    Soon, En Loong; Razak, Hamid Rahmatullah Bin Abd; Tan, Andrew Hwee Chye

    2017-01-01

    Introduction: Massive rotator cuff tears (RCTs) in the context of shoulder dislocations are relatively uncommon in the young adult (<40 years) and if reported are more commonly described in association with acute traumatic anterior glenohumeral dislocations. They have rarely been described with posterior dislocations, regardless of patient age. This is the 1st case reported in the context of posterior dislocations, where a triad of biceps tendon rupture, posterior dislocation, and RCTs was observed during surgery. It provides an important reminder to readers about certain injuries commonly overlooked during the assessment of an acute traumatic shoulder. Case Report: We report an atypical case of a massive RCT involving a 34-year-old Asian male who landed on his outstretched hand after falling off a bicycle. A tear involving the supraspinatus and subscapularis was visualized during surgery, along with long head of biceps (LHB) tendon rupture. This was after an initial failure to achieve closed reduction of the posteriorly dislocated left shoulder. Conclusion: It is easy to miss the posterior instability, the associated RCTs or the biceps tendon injuries. Biceps tendon rupture should be a consideration when one is unable to reduce a posteriorly dislocated shoulder. The interposed torn LHB tendon trapped within the glenohumeral joint was the likely physical block in the initial failure to achieve closed reduction. With timely diagnosis, prudent physical examination, early imaging and surgery, and excellent results can potentially be achieved to return a young patient to full functionality. PMID:28819610

  5. Collective behaviour of dislocations in a finite medium

    NASA Astrophysics Data System (ADS)

    Kooiman, M.; Hütter, M.; Geers, M. G. D.

    2014-04-01

    We derive the grand-canonical partition function of straight and parallel dislocation lines without making a priori assumptions on the temperature regime. Such a systematic derivation for dislocations has, to the best of our knowledge, not been carried out before, and several conflicting assumptions on the free energy of dislocations have been made in the literature. Dislocations have gained interest as they are the carriers of plastic deformation in crystalline materials and solid polymers, and they constitute a prototype system for two-dimensional Coulomb particles. Our microscopic starting level is the description of dislocations as used in the discrete dislocation dynamics (DDD) framework. The macroscopic level of interest is characterized by the temperature, the boundary deformation and the dislocation density profile. By integrating over state space, we obtain a field theoretic partition function, which is a functional integral of the Boltzmann weight over an auxiliary field. The Hamiltonian consists of a term quadratic in the field and an exponential of this field. The partition function is strongly non-local, and reduces in special cases to the sine-Gordon model. Moreover, we determine implicit expressions for the response functions and the dominant scaling regime for metals, namely the low-temperature regime.

  6. Singularity-free dislocation dynamics with strain gradient elasticity

    NASA Astrophysics Data System (ADS)

    Po, Giacomo; Lazar, Markus; Seif, Dariush; Ghoniem, Nasr

    2014-08-01

    The singular nature of the elastic fields produced by dislocations presents conceptual challenges and computational difficulties in the implementation of discrete dislocation-based models of plasticity. In the context of classical elasticity, attempts to regularize the elastic fields of discrete dislocations encounter intrinsic difficulties. On the other hand, in gradient elasticity, the issue of singularity can be removed at the outset and smooth elastic fields of dislocations are available. In this work we consider theoretical and numerical aspects of the non-singular theory of discrete dislocation loops in gradient elasticity of Helmholtz type, with interest in its applications to three dimensional dislocation dynamics (DD) simulations. The gradient solution is developed and compared to its singular and non-singular counterparts in classical elasticity using the unified framework of eigenstrain theory. The fundamental equations of curved dislocation theory are given as non-singular line integrals suitable for numerical implementation using fast one-dimensional quadrature. These include expressions for the interaction energy between two dislocation loops and the line integral form of the generalized solid angle associated with dislocations having a spread core. The single characteristic length scale of Helmholtz elasticity is determined from independent molecular statics (MS) calculations. The gradient solution is implemented numerically within our variational formulation of DD, with several examples illustrating the viability of the non-singular solution. The displacement field around a dislocation loop is shown to be smooth, and the loop self-energy non-divergent, as expected from atomic configurations of crystalline materials. The loop nucleation energy barrier and its dependence on the applied shear stress are computed and shown to be in good agreement with atomistic calculations. DD simulations of Lome-Cottrell junctions in Al show that the strength of the

  7. Arthroscopic evaluation and management after repeated luxatio erecta of the glenohumeral joint.

    PubMed

    Tracy, Sean C; Myer, Jonathan J

    2009-05-01

    Luxatio erecta, inferior dislocation of the glenohumeral joint, is a relatively rare type of glenohumeral dislocation, accounting for <0.5% of all shoulder dislocations. It has been well described in terms of presentation and conservative management. Arthroscopic findings after the more commonly found anteroinferior glenohumeral dislocation have also been described. However, we know of only 1 case report that details the arthroscopic findings and open surgical management in a patient who sustained a single episode of luxatio erecta. Additionally, we were unable to find any reports in the literature of the arthroscopic management of this type of dislocation. We present the arthroscopic findings and arthroscopic management of an 18-year-old male college football player who reported 7 episodes of left shoulder luxatio erecta. Arthroscopic evaluation revealed an extensive anterior capsulolabral injury as well as a superior labrum anteroposterior (SLAP) tear. Additionally, there were extensive articular cartilage changes of the anterosuperior glenoid, a posterior Hill-Sachs lesion, and an anterosuperior humeral head cartilage indentation. The anterior capsulolabral injury and the SLAP lesion were fixed arthroscopically with suture anchors. The remainder of the lesions were debrided. The patient was able to return to college-level football and reported no further episodes of instability, pain, or stiffness at 3-year follow-up.

  8. Modeling of dislocation dynamics in germanium Czochralski growth

    NASA Astrophysics Data System (ADS)

    Artemyev, V. V.; Smirnov, A. D.; Kalaev, V. V.; Mamedov, V. M.; Sidko, A. P.; Podkopaev, O. I.; Kravtsova, E. D.; Shimansky, A. F.

    2017-06-01

    Obtaining very high-purity germanium crystals with low dislocation density is a practically difficult problem, which requires knowledge and experience in growth processes. Dislocation density is one of the most important parameters defining the quality of germanium crystal. In this paper, we have performed experimental study of dislocation density during 4-in. germanium crystal growth using the Czochralski method and comprehensive unsteady modeling of the same crystal growth processes, taking into account global heat transfer, melt flow and melt/crystal interface shape evolution. Thermal stresses in the crystal and their relaxation with generation of dislocations within the Alexander-Haasen model have been calculated simultaneously with crystallization dynamics. Comparison to experimental data showed reasonable agreement for the temperature, interface shape and dislocation density in the crystal between calculation and experiment.

  9. Implementation of the nudged elastic band method in a dislocation dynamics formalism: Application to dislocation nucleation

    NASA Astrophysics Data System (ADS)

    Geslin, Pierre-Antoine; Gatti, Riccardo; Devincre, Benoit; Rodney, David

    2017-11-01

    We propose a framework to study thermally-activated processes in dislocation glide. This approach is based on an implementation of the nudged elastic band method in a nodal mesoscale dislocation dynamics formalism. Special care is paid to develop a variational formulation to ensure convergence to well-defined minimum energy paths. We also propose a methodology to rigorously parametrize the model on atomistic data, including elastic, core and stacking fault contributions. To assess the validity of the model, we investigate the homogeneous nucleation of partial dislocation loops in aluminum, recovering the activation energies and loop shapes obtained with atomistic calculations and extending these calculations to lower applied stresses. The present method is also applied to heterogeneous nucleation on spherical inclusions.

  10. Isolated dorsal dislocation of the tarsal naviculum

    PubMed Central

    Hamdi, Kaziz; Hazem, Ben Ghozlen; Yadh, Zitoun; Faouzi, Abid

    2015-01-01

    Isolated dislocation of the tarsal naviculum is an unusual injury, scarcely reported in the literature. The naviculum is surrounded by the rigid bony and ligamentous support hence fracture dislocation is more common than isolated dislocation. The mechanism and treatment options remain unclear. In this case report, we describe a 31 year old man who sustained an isolated dorsal dislocation of the left tarsal naviculum, without fracture, when he was involved in a motor vehicle collision. The reported mechanism of the dislocation is a hyper plantar flexion force applied to the midfoot, resulting in a transient disruption of the ligamentous support of the naviculum bone, with dorsal displacement of the bone. The patient was treated with open reduction and Krischner-wire fixation of the navicular after the failure of closed reduction. The wires were removed after 6 weeks postoperatively. Physiotherapy for stiffness and midfoot pain was recommended for 2 months. At 6 months postoperatively, limping, midfoot pain and weakness were reported, no X-ray abnormalities were found. The patient returned to his obvious activities with a normal range of motion. PMID:26806978

  11. A hierarchical dislocation-grain boundary interaction model based on 3D discrete dislocation dynamics and molecular dynamics

    NASA Astrophysics Data System (ADS)

    Gao, Yuan; Zhuang, Zhuo; You, XiaoChuan

    2011-04-01

    We develop a new hierarchical dislocation-grain boundary (GB) interaction model to predict the mechanical behavior of polycrystalline metals at micro and submicro scales by coupling 3D Discrete Dislocation Dynamics (DDD) simulation with the Molecular Dynamics (MD) simulation. At the microscales, the DDD simulations are responsible for capturing the evolution of dislocation structures; at the nanoscales, the MD simulations are responsible for obtaining the GB energy and ISF energy which are then transferred hierarchically to the DDD level. In the present model, four kinds of dislocation-GB interactions, i.e. transmission, absorption, re-emission and reflection, are all considered. By this methodology, the compression of a Cu micro-sized bi-crystal pillar is studied. We investigate the characteristic mechanical behavior of the bi-crystal compared with that of the single-crystal. Moreover, the comparison between the present penetrable model of GB and the conventional impenetrable model also shows the accuracy and efficiency of the present model.

  12. Thermodynamic theory of dislocation-enabled plasticity

    NASA Astrophysics Data System (ADS)

    Langer, J. S.

    2017-11-01

    The thermodynamic theory of dislocation-enabled plasticity is based on two unconventional hypotheses. The first of these is that a system of dislocations, driven by external forces and irreversibly exchanging heat with its environment, must be characterized by a thermodynamically defined effective temperature that is not the same as the ordinary temperature. The second hypothesis is that the overwhelmingly dominant mechanism controlling plastic deformation is thermally activated depinning of entangled pairs of dislocations. This paper consists of a systematic reformulation of this theory followed by examples of its use in analyses of experimentally observed phenomena including strain hardening, grain-size (Hall-Petch) effects, yielding transitions, and adiabatic shear banding.

  13. Elasticity and dislocation inelasticity of crystals

    NASA Astrophysics Data System (ADS)

    Nikanorov, S. P.; Kardashev, B. K.

    The use of methods of physical acoustics for studying the elasticity and dislocation inelasticity of crystals is discussed, as is the application of the results of such studies to the analysis of interatomic and lattice defect interactions. The analysis of the potential functions determining the energy of interatomic interactions is based on an analysis of the elastic properties of crystals over a wide temperature range. The data on the dislocation structure and the interaction between dislocations and point defects are obtained from a study of inelastic effects. Particular attention is given to the relationship between microplastic effects under conditions of elastic oscillations and the initial stage of plastic deformation.

  14. Pair Interaction of Dislocations in Two-Dimensional Crystals

    NASA Astrophysics Data System (ADS)

    Eisenmann, C.; Gasser, U.; Keim, P.; Maret, G.; von Grünberg, H. H.

    2005-10-01

    The pair interaction between crystal dislocations is systematically explored by analyzing particle trajectories of two-dimensional colloidal crystals measured by video microscopy. The resulting pair energies are compared to Monte Carlo data and to predictions derived from the standard Hamiltonian of the elastic theory of dislocations. Good agreement is found with respect to the distance and temperature dependence of the interaction potential, but not regarding the angle dependence where discrete lattice effects become important. Our results on the whole confirm that the dislocation Hamiltonian allows a quantitative understanding of the formation and interaction energies of dislocations in two-dimensional crystals.

  15. Thermal activation of dislocations in large scale obstacle bypass

    NASA Astrophysics Data System (ADS)

    Sobie, Cameron; Capolungo, Laurent; McDowell, David L.; Martinez, Enrique

    2017-08-01

    Dislocation dynamics simulations have been used extensively to predict hardening caused by dislocation-obstacle interactions, including irradiation defect hardening in the athermal case. Incorporating the role of thermal energy on these interactions is possible with a framework provided by harmonic transition state theory (HTST) enabling direct access to thermally activated reaction rates using the Arrhenius equation, including rates of dislocation-obstacle bypass processes. Moving beyond unit dislocation-defect reactions to a representative environment containing a large number of defects requires coarse-graining the activation energy barriers of a population of obstacles into an effective energy barrier that accurately represents the large scale collective process. The work presented here investigates the relationship between unit dislocation-defect bypass processes and the distribution of activation energy barriers calculated for ensemble bypass processes. A significant difference between these cases is observed, which is attributed to the inherent cooperative nature of dislocation bypass processes. In addition to the dislocation-defect interaction, the morphology of the dislocation segments pinned to the defects play an important role on the activation energies for bypass. A phenomenological model for activation energy stress dependence is shown to describe well the effect of a distribution of activation energies, and a probabilistic activation energy model incorporating the stress distribution in a material is presented.

  16. Influence of strain on dislocation core in silicon

    NASA Astrophysics Data System (ADS)

    Pizzagalli, L.; Godet, J.; Brochard, S.

    2018-05-01

    First principles, density functional-based tight binding and semi-empirical interatomic potentials calculations are performed to analyse the influence of large strains on the structure and stability of a 60? dislocation in silicon. Such strains typically arise during the mechanical testing of nanostructures like nanopillars or nanoparticles. We focus on bi-axial strains in the plane normal to the dislocation line. Our calculations surprisingly reveal that the dislocation core structure largely depends on the applied strain, for strain levels of about 5%. In the particular case of bi-axial compression, the transformation of the dislocation to a locally disordered configuration occurs for similar strain magnitudes. The formation of an opening, however, requires larger strains, of about 7.5%. Furthermore, our results suggest that electronic structure methods should be favoured to model dislocation cores in case of large strains whenever possible.

  17. HiL simulation in biomechanics: a new approach for testing total joint replacements.

    PubMed

    Herrmann, Sven; Kaehler, Michael; Souffrant, Robert; Rachholz, Roman; Zierath, János; Kluess, Daniel; Mittelmeier, Wolfram; Woernle, Christoph; Bader, Rainer

    2012-02-01

    Instability of artificial joints is still one of the most prevalent reasons for revision surgery caused by various influencing factors. In order to investigate instability mechanisms such as dislocation under reproducible, physiologically realistic boundary conditions, a novel test approach is introduced by means of a hardware-in-the-loop (HiL) simulation involving a highly flexible mechatronic test system. In this work, the underlying concept and implementation of all required units is presented enabling comparable investigations of different total hip and knee replacements, respectively. The HiL joint simulator consists of two units: a physical setup composed of a six-axes industrial robot and a numerical multibody model running in real-time. Within the multibody model, the anatomical environment of the considered joint is represented such that the soft tissue response is accounted for during an instability event. Hence, the robot loads and moves the real implant components according to the information provided by the multibody model while transferring back the position and resisting moment recorded. Functionality of the simulator is proved by testing the underlying control principles, and verified by reproducing the dislocation process of a standard total hip replacement. HiL simulations provide a new biomechanical testing tool for analyzing different joint replacement systems with respect to their instability behavior under realistic movements and physiological load conditions. Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.

  18. The relationship between strain geometry and geometrically necessary dislocations

    NASA Astrophysics Data System (ADS)

    Hansen, Lars; Wallis, David

    2016-04-01

    The kinematics of past deformations are often a primary goal in structural analyses of strained rocks. Details of the strain geometry, in particular, can help distinguish hypotheses about large-scale tectonic phenomena. Microstructural indicators of strain geometry have been heavily utilized to investigate large-scale kinematics. However, many of the existing techniques require structures for which the initial morphology is known, and those structures must undergo the same deformation as imposed macroscopically. Many deformed rocks do not exhibit such convenient features, and therefore the strain geometry is often difficult (if not impossible) to ascertain. Alternatively, crystallographic textures contain information about the strain geometry, but the influence of strain geometry can be difficult to separate from other environmental factors that might affect slip system activity and therefore the textural evolution. Here we explore the ability for geometrically necessary dislocations to record information about the deformation geometry. It is well known that crystallographic slip due to the motion of dislocations yields macroscopic plastic strain, and the mathematics are established to relate dislocation glide on multiple slip systems to the strain tensor of a crystal. This theoretical description generally assumes that dislocations propagate across the entire crystal. However, at any point during the deformation, dislocations are present that have not fully transected the crystal, existing either as free dislocations or as dislocations organized into substructures like subgrain boundaries. These dislocations can remain in the lattice after deformation if the crystal is quenched sufficiently fast, and we hypothesize that this residual dislocation population can be linked to the plastic strain geometry in a quantitative manner. To test this hypothesis, we use high-resolution electron backscatter diffraction to measure lattice curvatures in experimentally deformed

  19. What Components Comprise the Measurement of the Tibial Tuberosity-Trochlear Groove Distance in a Patellar Dislocation Population?

    PubMed

    Tensho, Keiji; Akaoka, Yusuke; Shimodaira, Hiroki; Takanashi, Seiji; Ikegami, Shota; Kato, Hiroyuki; Saito, Naoto

    2015-09-02

    tibial tubercle transfer may not be appropriate. Surgical decisions of tibial tubercle transfer should be made after the careful analysis of several underlying factors of patellar dislocation. Copyright © 2015 by The Journal of Bone and Joint Surgery, Incorporated.

  20. How to identify dislocations in molecular dynamics simulations?

    NASA Astrophysics Data System (ADS)

    Li, Duo; Wang, FengChao; Yang, ZhenYu; Zhao, YaPu

    2014-12-01

    Dislocations are of great importance in revealing the underlying mechanisms of deformed solid crystals. With the development of computational facilities and technologies, the observations of dislocations at atomic level through numerical simulations are permitted. Molecular dynamics (MD) simulation suggests itself as a powerful tool for understanding and visualizing the creation of dislocations as well as the evolution of crystal defects. However, the numerical results from the large-scale MD simulations are not very illuminating by themselves and there exist various techniques for analyzing dislocations and the deformed crystal structures. Thus, it is a big challenge for the beginners in this community to choose a proper method to start their investigations. In this review, we summarized and discussed up to twelve existing structure characterization methods in MD simulations of deformed crystal solids. A comprehensive comparison was made between the advantages and disadvantages of these typical techniques. We also examined some of the recent advances in the dynamics of dislocations related to the hydraulic fracturing. It was found that the dislocation emission has a significant effect on the propagation and bifurcation of the crack tip in the hydraulic fracturing.

  1. Strain field mapping of dislocations in a Ge/Si heterostructure.

    PubMed

    Liu, Quanlong; Zhao, Chunwang; Su, Shaojian; Li, Jijun; Xing, Yongming; Cheng, Buwen

    2013-01-01

    Ge/Si heterostructure with fully strain-relaxed Ge film was grown on a Si (001) substrate by using a two-step process by ultra-high vacuum chemical vapor deposition. The dislocations in the Ge/Si heterostructure were experimentally investigated by high-resolution transmission electron microscopy (HRTEM). The dislocations at the Ge/Si interface were identified to be 90° full-edge dislocations, which are the most efficient way for obtaining a fully relaxed Ge film. The only defect found in the Ge epitaxial film was a 60° dislocation. The nanoscale strain field of the dislocations was mapped by geometric phase analysis technique from the HRTEM image. The strain field around the edge component of the 60° dislocation core was compared with those of the Peierls-Nabarro and Foreman dislocation models. Comparison results show that the Foreman model with a = 1.5 can describe appropriately the strain field around the edge component of a 60° dislocation core in a relaxed Ge film on a Si substrate.

  2. The strength and dislocation microstructure evolution in superalloy microcrystals

    NASA Astrophysics Data System (ADS)

    Hussein, Ahmed M.; Rao, Satish I.; Uchic, Michael D.; Parthasarathay, Triplicane A.; El-Awady, Jaafar A.

    2017-02-01

    In this work, the evolution of the dislocations microstructure in single crystal two-phase superalloy microcrystals under monotonic loading has been studied using the three-dimensional discrete dislocation dynamics (DDD) method. The DDD framework has been extended to properly handle the collective behavior of dislocations and their interactions with large collections of arbitrary shaped precipitates. Few constraints are imposed on the initial distribution of the dislocations or the precipitates, and the extended DDD framework can support experimentally-obtained precipitate geometries. Full tracking of the creation and destruction of anti-phase boundaries (APB) is accounted for. The effects of the precipitate volume fraction, APB energy, precipitate size, and crystal size on the deformation of superalloy microcrystals have been quantified. Correlations between the precipitate microstructure and the dominant deformation features, such as dislocation looping versus precipitate shearing, are also discussed. It is shown that the mechanical strength is independent of the crystal size, increases linearly with increasing the volume fraction, follows a near square-root relationship with the APB energy and an inverse square-root relationship with the precipitate size. Finally, the flow strength in simulations having initial dislocation pair sources show a flow strength that is about one half of that predicted from simulations starting with single dislocation sources. The method developed can be used, with minimal extensions, to simulate dislocation microstructure evolution in general multiphase materials.

  3. Thermodynamic theory of dislocation-enabled plasticity

    DOE PAGES

    Langer, J. S.

    2017-11-30

    The thermodynamic theory of dislocation-enabled plasticity is based on two unconventional hypotheses. The first of these is that a system of dislocations, driven by external forces and irreversibly exchanging heat with its environment, must be characterized by a thermodynamically defined effective temperature that is not the same as the ordinary temperature. The second hypothesis is that the overwhelmingly dominant mechanism controlling plastic deformation is thermally activated depinning of entangled pairs of dislocations. This paper consists of a systematic reformulation of this theory followed by examples of its use in analyses of experimentally observed phenomena including strain hardening, grain-size (Hall-Petch) effects,more » yielding transitions, and adiabatic shear banding.« less

  4. Rare Inferior Shoulder Dislocation (Luxatio Erecta)

    PubMed Central

    Cift, Hakan; Soylemez, Salih; Demiroglu, Murat; Ozkan, Korhan; Ozden, Vahit Emre; Ozkut, Afsar T.

    2015-01-01

    Although shoulder dislocations have been seen very frequently, inferior dislocation of shoulder constitutes only 0.5% of all shoulder dislocations. We share our 4 patients with luxatio erecta and present their last clinical control. 2 male and 2 female Caucasian patients were diagnosed as luxatio erecta. Patients' ages were 78, 62, 65, and 76. All patients' reduction was done by traction-abduction and contour traction maneuver in the operating room. The patients had no symptoms and no limitation of range of motion of their shoulder at their last control. Luxatio erecta is seen rarely, and these patients may have neurovascular injury. These patients should be carefully examined and treated by the orthopaedic and traumatology surgeons. PMID:25883820

  5. Saipan and Joint Operations

    DTIC Science & Technology

    1990-02-12

    following postwar joint education objectives for ths armed forces: Objective i: To oroduce within each component of the armed forces a general knowledge...had acquired the pradtical knowledge to establieh::thvoe Joint educational goals which are as relevant today as when they were written. ENDNOTES 1...F2:", (- 1-1 1’A I’rn ,r’ lqA ,! Vim l ;` thO? C’~~~~~~~ a m in A i h9%t ý A din r, a INi m i t z% "h e haa I.z a:wn naval. +ac! lit! es, line~i n+f

  6. Anterior cervical distraction and screw elevating–pulling reduction for traumatic cervical spine fractures and dislocations

    PubMed Central

    Li, Haoxi; Yong, Zhiyao; Chen, Zhaoxiong; Huang, Yufeng; Lin, Zhoudan; Wu, Desheng

    2017-01-01

    Abstract Treatment of cervical fracture and dislocation by improving the anterior cervical technique. Anterior cervical approach has been extensively used in treating cervical spine fractures and dislocations. However, when this approach is used in the treatment of locked facet joints, an unsatisfactory intraoperative reduction and prying reduction increases the risk of secondary spinal cord injury. Thus, herein, the cervical anterior approach was improved. With distractor and screw elevation therapy during surgery, the restoration rate is increased, and secondary injury to the spinal cord is avoided. To discuss the feasibility of the surgical method of treating traumatic cervical spine fractures and dislocations and the clinical application. This retrospective study included the duration of patients’ hospitalization from January 2005 to June 2015. The potential risks of surgery (including death and other surgical complications) were explained clearly, and written consents were obtained from all patients before surgery. The study was conducted on 86 patients (54 males and 32 females, average age of 40.1 ± 5.6 years) with traumatic cervical spine fractures and dislocations, who underwent one-stage anterior approach treatment. The effective methods were evaluated by postoperative follow-up. The healing of the surgical incision was monitored in 86 patients. The follow-up duration was 18 to 36 (average 26.4 ± 7.1) months. The patients achieved bones grafted fusion and restored spine stability in 3 to 9 (average 6) months after the surgery. Statistically, significant improvement was observed by Frankel score, visual analog scale score, Japanese Orthopedic Association score, and correction rate of the cervical spine dislocation pre- and postoperative (P < .01). The modified anterior cervical approach is simple with a low risk but a good effect in reduction. In addition, it can reduce the risk of iatrogenic secondary spinal cord injury and maintain optimal

  7. Statistical description of the motion of dislocation kinks in a random field of impurities adsorbed by a dislocation

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Petukhov, B. V., E-mail: petukhov@ns.crys.ras.r

    2010-01-15

    A model has been proposed for describing the influence of impurities adsorbed by dislocation cores on the mobility of dislocation kinks in materials with a high crystalline relief (Peierls barriers). The delay time spectrum of kinks at statistical fluctuations of the impurity density has been calculated for a sufficiently high energy of interaction between impurities and dislocations when the migration potential is not reduced to a random Gaussian potential. It has been shown that fluctuations in the impurity distribution substantially change the character of the migration of dislocation kinks due to the slow decrease in the probability of long delaymore » times. The dependences of the position of the boundary of the dynamic phase transition to a sublinear drift of kinks x {proportional_to} t{sup {delta}} ({delta} {sigma} 1) and the characteristics of the anomalous mobility on the physical parameters (stress, impurity concentration, experimental temperature, etc.) have been calculated.« less

  8. Atomistically determined phase-field modeling of dislocation dissociation, stacking fault formation, dislocation slip, and reactions in fcc systems

    NASA Astrophysics Data System (ADS)

    Rezaei Mianroodi, Jaber; Svendsen, Bob

    2015-04-01

    The purpose of the current work is the development of a phase field model for dislocation dissociation, slip and stacking fault formation in single crystals amenable to determination via atomistic or ab initio methods in the spirit of computational material design. The current approach is based in particular on periodic microelasticity (Wang and Jin, 2001; Bulatov and Cai, 2006; Wang and Li, 2010) to model the strongly non-local elastic interaction of dislocation lines via their (residual) strain fields. These strain fields depend in turn on phase fields which are used to parameterize the energy stored in dislocation lines and stacking faults. This energy storage is modeled here with the help of the "interface" energy concept and model of Cahn and Hilliard (1958) (see also Allen and Cahn, 1979; Wang and Li, 2010). In particular, the "homogeneous" part of this energy is related to the "rigid" (i.e., purely translational) part of the displacement of atoms across the slip plane, while the "gradient" part accounts for energy storage in those regions near the slip plane where atomic displacements deviate from being rigid, e.g., in the dislocation core. Via the attendant global energy scaling, the interface energy model facilitates an atomistic determination of the entire phase field energy as an optimal approximation of the (exact) atomistic energy; no adjustable parameters remain. For simplicity, an interatomic potential and molecular statics are employed for this purpose here; alternatively, ab initio (i.e., DFT-based) methods can be used. To illustrate the current approach, it is applied to determine the phase field free energy for fcc aluminum and copper. The identified models are then applied to modeling of dislocation dissociation, stacking fault formation, glide and dislocation reactions in these materials. As well, the tensile loading of a dislocation loop is considered. In the process, the current thermodynamic picture is compared with the classical mechanical

  9. Linear complexions: Confined chemical and structural states at dislocations

    NASA Astrophysics Data System (ADS)

    Kuzmina, M.; Herbig, M.; Ponge, D.; Sandlöbes, S.; Raabe, D.

    2015-09-01

    For 5000 years, metals have been mankind’s most essential materials owing to their ductility and strength. Linear defects called dislocations carry atomic shear steps, enabling their formability. We report chemical and structural states confined at dislocations. In a body-centered cubic Fe-9 atomic percent Mn alloy, we found Mn segregation at dislocation cores during heating, followed by formation of face-centered cubic regions but no further growth. The regions are in equilibrium with the matrix and remain confined to the dislocation cores with coherent interfaces. The phenomenon resembles interface-stabilized structural states called complexions. A cubic meter of strained alloy contains up to a light year of dislocation length, suggesting that linear complexions could provide opportunities to nanostructure alloys via segregation and confined structural states.

  10. Scattering of phonons by dislocations

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Anderson, A. C.

    1979-01-01

    By 1950, an explicit effort had been launched to use lattice thermal conductivity measurements in the investigation of defect structures in solids. This technique has been highly successful, especially when combined with the measurements of other properties such as optical absorption. One exception has been the study of dislocations. Although dislocations have a profound effect on the phonon thermal conductivity, the mechanisms of the phonon-dislocation interaction are poorly understood. The most basic questions are still debated in the literature. It therefore is pointless to attempt a quantitative comparison between an extensive accumulation of experimental data on the one hand, andmore » the numerous theoretical models on the other. Instead, this chapter will attempt to glean a few qualitative conclusions from the existing experimental data. These results will then be compared with two general models which incorporate, in a qualitative manner, most of the proposed theories of the phonon-dislocation interaction. Until very recently, measurement of thermal conductivity was the only means available to probe the interaction between phonons and defects at phonon frequencies above the standard ultrasonic range of approx. = 10/sup 9/ Hz. The introductory paragraphs provide a brief review of the thermal-conductivity technique and the problems which are encountered in practice. There is also a brief presentation of the theoretical models and the complications that may occur in more realistic situations.« less

  11. The hematoma block: a simple, effective technique for closed reduction of ankle fracture dislocations.

    PubMed

    Ross, Adrianne; Catanzariti, Alan R; Mendicino, Robert W

    2011-01-01

    Management of a dislocated ankle fracture can be challenging because of instability of the ankle mortise, a compromised soft tissue envelope, and the potential neurovascular compromise. Every effort should be made to quickly and efficiently relocate the disrupted ankle joint. Within the emergency department setting, narcotics and benzodiazepines can be used to sedate the patient before attempting closed reduction. The combination of narcotics and benzodiazepines provides relief of pain and muscle guarding; however, it conveys a risk of seizure as well as respiratory arrest. An alternative to conscious sedation is the hematoma block, or an intra-articular local anesthetic injection in the ankle joint and the associated fracture hematoma. The hematoma block offers a comparable amount of analgesia to conscious sedation without the additional cardiovascular risk, hospital cost, and procedure time. Copyright © 2011 American College of Foot and Ankle Surgeons. Published by Elsevier Inc. All rights reserved.

  12. Dislocation nucleation facilitated by atomic segregation

    DOE PAGES

    Zou, Lianfeng; Yang, Chaoming; Lei, Yinkai; ...

    2017-11-27

    Surface segregation—the enrichment of one element at the surface, relative to the bulk—is ubiquitous to multi-component materials. Using the example of a Cu–Au solid solution, we demonstrate that compositional variations induced by surface segregation are accompanied by misfit strain and the formation of dislocations in the subsurface region via a surface di˙usion and trapping process. The resulting chemically ordered surface regions acts as an e˙ective barrier that inhibits subsequent dislocation annihilation at free surfaces. Using dynamic, atomic-scale resolution electron microscopy observations and theory modelling, we show that the dislocations are highly active, and we delineate the specific atomic-scale mechanisms associatedmore » with their nucleation, glide, climb, and annihilation at elevated temperatures. As a result, these observations provide mechanistic detail of how dislocations nucleate and migrate at heterointerfaces in dissimilar-material systems.« less

  13. Dislocation core structures of tungsten with dilute solute hydrogen

    NASA Astrophysics Data System (ADS)

    Wang, Yinan; Li, Qiulin; Li, Chengliang; Shu, Guogang; Xu, Ben; Liu, Wei

    2017-12-01

    In this paper, a combination of quantum mechanical and interatomic potential-based atomistic calculations are used to predict the core structures of screw and edge dislocations in tungsten in the presence of a particular concentration of hydrogen atoms. These configurations of the core structures are the results of two competing energies: the interaction between the partial dislocations and the corresponding generalized stacking fault energy in between the two partial dislocations, which are presented in this work. With this, we can precisely predict the configurations of the hydrogen-doped dislocation core structures.

  14. Two Patients with Osteochondral Injury of the Weight-Bearing Portion of the Lateral Femoral Condyle Associated with Lateral Dislocation of the Patella

    PubMed Central

    Inoue, Hiroaki; Atsumi, Satoru; Ichimaru, Shohei; Fujiwara, Hiroyoshi; Kubo, Toshikazu

    2014-01-01

    Complications of patellar dislocation include osteochondral injury of the lateral femoral condyle and patella. Most cases of osteochondral injury occur in the anterior region, which is the non-weight-bearing portion of the lateral femoral condyle. We describe two patients with osteochondral injury of the weight-bearing surface of the lateral femoral condyle associated with lateral dislocation of the patella. The patients were 18- and 11-year-old females. Osteochondral injury occurred on the weight-bearing surface distal to the lateral femoral condyle. The presence of a free osteochondral fragment and osteochondral injury of the lateral femoral condyle was confirmed on MRI and reconstruction CT scan. Treatment consisted of osteochondral fragment fixation or microfracture, as well as patellar stabilization. Osteochondral injury was present in the weight-bearing portion of the lateral femoral condyle in both patients, suggesting that the injury was caused by friction between the patella and lateral femoral condyle when the patella was dislocated or reduced at about 90° flexion of the knee joint. These findings indicate that patellar dislocation may occur and osteochondral injury may extend to the weight-bearing portion of the femur even in deep flexion, when the patella is stabilized on the bones of the femoral groove. PMID:25506015

  15. The equivalence between dislocation pile-ups and cracks

    NASA Technical Reports Server (NTRS)

    Liu, H. W.; Gao, Q.

    1990-01-01

    Cracks and dislocation pile-ups are equivalent to each other. In this paper, the physical equivalence between cracks and pile-ups is delineated, and the relationshps between crack-extension force, force on the leading dislocation, stress-intensity factor, and dislocation density are reviewed and summarized. These relations make it possible to extend quantitatively the recent advances in the concepts and practices of fracture mechanics to the studies of microfractures and microplastic deformations.

  16. Management of proximal interphalangeal joint injuries

    PubMed Central

    Freiberg, Arnis

    2007-01-01

    Injuries to the proximal interphalangeal joint are common but frequently missed. They are often overtreated by prolonged immobilization, resulting in stiffness, which may be permanent. The purpose of the present article is to briefly review the relevant anatomy and biomechanics, present an approach to physical examination and diagnosis, and propose a practical clinical classification. The treatment of the most severe injury – the intra-articular fracture dislocation – is controversial. The various treatment options are discussed, based on personal experience and a review of the literature. A list of relevant references is presented. PMID:19554177

  17. [Double Endobutto reconstituting coracoclavicular ligament combined with repairing acromioclavicular ligament at stage I for the treatment of acromioclavicular dislocation with Rockwood type III - V].

    PubMed

    Hu, Wen-yue; Yu, Chong; Huang, Zhong-ming; Han, Lei

    2015-06-01

    To explore clinical efficacy of double Endobutto reconstituting coracoclavicular ligament combined with repairing acromioclavicular ligament in stage I in treating acromioclavicular dislocation with Rockwood type III - V . From January 2010 to September 2013, 56 patients with Rockwood type III - V acromioclavicular dislocation were treated by operation, including 20 males and 36 femlaes, aged from 32 to 52 years old with an average of 38.5 years old. Twenty-five patients were on the left side and 31 cases on the right side. The time from injury to operation was from 3 to 14 days, averaged 7 days. All patients were diagnosed as acromioclavicular dislocation with Rockwood type III - V, and double Endobutto were used to reconstituting coracoclavicular ligament, line metal anchors were applied for repairing acromioclavicular ligament. Postoperative complications were observed, Karlsson and Constant-Murley evaluation standard were used to evaluate clinical effects. All patients were followed up from 8 to 24 months with average of 11 months. According to Karlsson evaluation standard at 6 months after operation,42 cases were grade A, 13 were grade B and 1 was grade C. Constant-Murley score were improved from (42.80±5.43) before operation to (91.75±4.27) at 6 months after operation. All items at 6 months after operation were better than that of preoperative items. Forty-eight patients got excellent results, 7 were moderate and only 1 with bad result. No shoulder joint adhesion, screw loosening or breakage were occurred during following up. Double Endobutto reconstituting coracoclavicular ligament combined with repairing acromioclavicular ligament in stage I for the treatment of acromioclavicular dislocation with Rockwood type III - V could obtain early staisfied clinical effects, and benefit for early recovery of shoulder joint function.

  18. AC Initiation System.

    DTIC Science & Technology

    An ac initiation system is described which uses three ac transmission signals interlocked for safety by frequency, phase, and power discrimination...The ac initiation system is pre-armed by the application of two ac signals have the proper phases, and activates a load when an ac power signal of the proper frequency and power level is applied. (Author)

  19. Limited distal clavicle excision of acromioclavicular joint osteoarthritis.

    PubMed

    Gokkus, K; Saylik, M; Atmaca, H; Sagtas, E; Aydin, A T

    2016-05-01

    Resection of the distal aspect of clavicle has a well-documented treatment modality in case of acromioclavicular joint osteoarthritis resistant to conservative treatment. Limited (mean ∼0.5cm distal end of clavicle resection) distal clavicle excision of A-C joint arthritis in cases resistant to conservative treatment may reduce the pain and improve the shoulder function. In this study, we retrospectively evaluated the results of limited distal clavicle excision of acromioclavicular joint osteoarthritis resistant to conservative treatment. All patients were evaluated by using the Visual Analogue Scale (VAS) and UCLA shoulder rating scale (University of California Los Angeles), either before surgery or final follow-up period for pain and functional results, respectively. A total of 110 patients (48 male, 62 female) with AC joint arthritis, treated between the years of 2008-2012, were retrospectively analyzed. A total of 30 patients (12 male, 18 female) who failed to show improvement with conservative treatment underwent limited surgical open excision of distal clavicle. The mean age of the study population was 52.5±1.2 years. The mean follow-up period was 27±1.3 months. The mean preoperative VAS score was 83.6±5.58 (range, 70-90) while mean VAS was 26.6±9.3 (range, 10-50) at the final follow-up. There was a statistically significant difference between pre- and postoperative VAS scores in patients who had treated by surgical approach (P<0.001). The mean UCLA score of the patients increased postoperatively from 11.5 (range, 9-14) to 29.2 (range, 27-32) at the final follow-up. There was a statistically significant difference between the two time periods with respect to UCLA scores (P<0.001). In patients with AC osteoarthritis resistant to conservative therapy, the hypothesized limited clavicle excision (mean ∼0.5cm distal end of clavicle resection with preserving coracoclavicular ligaments and inferior capsule) reduced the pain and improved the shoulder function

  20. On damping of screw dislocation bending vibrations in dissipative crystal: limiting cases

    NASA Astrophysics Data System (ADS)

    Dezhin, V. V.

    2018-03-01

    The expression for the generalized susceptibility of the dislocation obtained earlier was used. The electronic drag mechanism of dislocations is considered. The study of small dislocation oscillations was limited. The contribution of the attenuation of low-frequency bending screw dislocation vibrations to the overall coefficient of dynamic dislocation drag in the long-wave and short-wave limits is calculated. The damping of short-wave bending screw dislocation vibrations caused by an external action of an arbitrary frequency has been investigated. The contribution of long-wave bending screw dislocation vibrations damping in the total drag coefficient at an arbitrary frequency is found.

  1. Bilateral Posterior Tibial Tendon and Flexor Digitorum Longus Dislocations.

    PubMed

    Padegimas, Eric M; Beck, David M; Pedowitz, David I

    2017-04-01

    The authors present a case of a previously healthy and athletic 17-year-old female who presented with a 3.5-year history of medial left ankle pain after sustaining an inversion injury while playing basketball. Prior to presentation, she had failed prior immobilization and physical therapy for a presumed ankles sprain. Physical examination revealed a dislocated posterior tibial tendon (PTT) that was temporarily reducible, but would spontaneously dislocate immediately after reduction. She had pain and snapping of the PTT with resisted ankle plantar flexion and resisted inversion as well as 4/5 strength in ankle inversion. The diagnosis of dislocated PTT was confirmed on magnetic resonance imaging (MRI). The patient underwent suture anchor repair of the medial retinaculum of the left ankle. At the time of surgery both the PTT and flexor digitorum longus (FDL) were dislocated. Three months postoperatively, the patient represented with PTT dislocation of the right (nonoperative) ankle confirmed by MRI. After failure of immobilization, physical therapy, and oral anti-inflammatory medications, the patient underwent suture anchor repair of the medial retinaculum of the right ankle. At 6 months postoperatively, the patient has 5/5 strength inversion bilaterally, no subluxation of either PTT, and has returned to all activities without limitation. The authors present this unique case of bilateral PTT dislocation and concurrent PTT/FDL dislocation along with review of the literature for PTT dislocation. The authors highlight the common misdaiganosis of this injury and highlight the successful results of surgical intervention. Level V: Case report.

  2. Glide of threading edge dislocations after basal plane dislocation conversion during 4H-SiC epitaxial growth

    NASA Astrophysics Data System (ADS)

    Abadier, Mina; Song, Haizheng; Sudarshan, Tangali S.; Picard, Yoosuf N.; Skowronski, Marek

    2015-05-01

    Transmission electron microscopy (TEM) and KOH etching were used to analyze the motion of dislocations after the conversion of basal plane dislocations (BPDs) to threading edge dislocations (TEDs) during 4H-SiC epitaxy. The locations of TED etch pits on the epilayer surface were shifted compared to the original locations of BPD etch pits on the substrate surface. The shift of the TED etch pits was mostly along the BPD line directions towards the up-step direction. For converted screw type BPDs, the conversion points were located below the substrate/epilayer interface. The shift distances in the step-flow direction were proportional to the depths of the BPD-TED conversion points below the substrate/epilayer interface. For converted mixed type BPDs, the conversion points were exactly at the interface. Through TEM analysis, it was concluded that the dislocation shift is caused by a combined effect of H2 etching prior to growth and glide of the threading segments during high temperature epitaxy. The TED glide is only possible for converted pure screw type BPDs and could present a viable means for eliminating BPDs from the epilayer during growth by moving the conversion point below the substrate/epilayer interface.

  3. Linear complexions: Confined chemical and structural states at dislocations.

    PubMed

    Kuzmina, M; Herbig, M; Ponge, D; Sandlöbes, S; Raabe, D

    2015-09-04

    For 5000 years, metals have been mankind's most essential materials owing to their ductility and strength. Linear defects called dislocations carry atomic shear steps, enabling their formability. We report chemical and structural states confined at dislocations. In a body-centered cubic Fe-9 atomic percent Mn alloy, we found Mn segregation at dislocation cores during heating, followed by formation of face-centered cubic regions but no further growth. The regions are in equilibrium with the matrix and remain confined to the dislocation cores with coherent interfaces. The phenomenon resembles interface-stabilized structural states called complexions. A cubic meter of strained alloy contains up to a light year of dislocation length, suggesting that linear complexions could provide opportunities to nanostructure alloys via segregation and confined structural states. Copyright © 2015, American Association for the Advancement of Science.

  4. Traumatic hip dislocation at a regional trauma centre in Nigeria.

    PubMed

    Onyemaechi, N O C; Eyichukwu, G O

    2011-01-01

    Traumatic dislocation or fracture-dislocation of the hip is an orthopaedic emergency that is steadily increasing in incidence due to high-speed motor vehicular accidents. These injuries need to be recognized early and promptly treated to prevent morbidity and long-term complications. Some of the fundamental issues in the management of traumatic dislocations of the hip are the critical interval between injury and reduction, the type of reduction most suitable for various types of injury and the duration of immobilization that give the best results. This study was carried out at the National Orthopaedic Hospital Enugu, a regional trauma and orthopaedic centre in South-East Nigeria. The purpose of the study is to describe the pattern of presentation and to identify the factors that determine the long-term outcome in the treatment of traumatic dislocations and fracture-dislocations of the hip at Enugu, Nigeria. The case notes of all the patients that presented with traumatic dislocations and fracture-dislocations of the hip between January 2003 and December 2007 were reviewed. The information extracted and analyzed included the patients' demographics, etiology of injury, time interval before reduction, associated injuries, treatment offered, complications and follow-up. Thompson-Epstein classification was used to grade the posterior hip dislocations. The outcome of treatment was evaluated using the clinical and radiological criteria proposed by Epstein (1974). Three patients with incomplete data and two patients with central fracture dislocation were excluded from this study. Forty-eight patients with 50 hip dislocations were analyzed. The age range was 12 years to 67 years with a mean age of 34.8 years. Thirty-nine patients (81.3%) were males and 9 (18.7%) were females. Road-traffic accident was the leading cause of traumatic hip dislocation in this series, 44 cases (91.6%). Posterior dislocation occurred in 48 hips (96%) while anterior dislocation occurred in 2 hips

  5. Management of traumatic patellar dislocation in a regional hospital in Hong Kong.

    PubMed

    Lee, H L; Yau, W P

    2017-04-01

    The role of surgery for acute patellar dislocation without osteochondral fracture is controversial. The aim of this study was to report the short-term results of management of patellar dislocation in our institute. Patients who were seen in our institution with patella dislocation from January 2011 to April 2014 were managed according to a standardised management algorithm. Pretreatment and 1-year post-treatment International Knee Documentation Committee score, Tegner activity level scale score, and presence of apprehension sign were analysed. A total of 41 patients were studied of whom 20 were first-time dislocators and 21 were recurrent dislocators. Among the first-time dislocators, there was a significant difference between patients who received conservative treatment versus surgical management. The conservative treatment group had a 33% recurrent dislocation rate, whereas there were no recurrent dislocations in the surgery group. There was no difference in Tegner activity level scale score or apprehension sign before and 1 year after treatment, however. Among the recurrent dislocators, there was a significant difference between those who received conservative treatment and those who underwent surgery. The recurrent dislocation rate was 71% in the conservative treatment group versus 0% in the surgery group. There was also significant improvement in International Knee Documentation Committee score from 67.7 to 80.0 (P=0.02), and of apprehension sign from 62% to 0% (P<0.01). A management algorithm for patellar dislocation is described. Surgery is preferable to conservative treatment in patients who have recurrent patellar dislocation, and may also be preferable for those who have an acute dislocation.

  6. Is coracoclavicular stabilisation alone sufficient for the endoscopic treatment of severe acromioclavicular joint dislocation (Rockwood types III, IV, and V)?

    PubMed

    Barth, J; Duparc, F; Andrieu, K; Duport, M; Toussaint, B; Bertiaux, S; Clavert, P; Gastaud, O; Brassart, N; Beaudouin, E; De Mourgues, P; Berne, D; Bahurel, J; Najihi, N; Boyer, P; Faivre, B; Meyer, A; Nourissat, G; Poulain, S; Bruchou, F; Ménard, J F

    2015-12-01

    The primary objective was to evaluate correlations linking anatomical to functional outcomes after endoscopically assisted repair of acute acromioclavicular joint dislocation (ACJD). Combined acromioclavicular and coracoclavicular stabilisation improves radiological outcomes compared to coracoclavicular stabilisation alone. A prospective multicentre study was performed. Clinical outcome measures were pain intensity on a visual analogue scale (VAS), subjective functional impairment (QuickDASH score), and Constant's score. Anatomical outcomes were assessed on standard radiographs (anteroposterior view of the acromioclavicular girdle and bilateral axillary views) obtained preoperatively and postoperatively and on postoperative dynamic radiographs taken as described by Tauber et al. Of 116 patients with acute ACJD included in the study, 48% had type III, 30% type IV, and 22% type V ACJD according to the Rockwood classification. Coracoclavicular stabilisation was achieved using a double endobutton in 93% of patients, and concomitant acromioclavicular stabilisation was performed in 50% of patients. The objective functional outcome was good, with an unweighted Constant's score ≥ 85/100 and a subjective QuickDASH functional disability score ≤ 10 in 75% of patients. The radiographic analysis showed significant improvements from the preoperative to the 1-year postoperative values in the vertical plane (decrease in the coracoclavicular ratio from 214 to 128%, p=10(-6)) and in the horizontal plane (decrease in posterior displacement from 4 to 0mm, p=5×10(-5)). The anatomical outcome correlated significantly with the functional outcome (absolute R value=0.19 and p=0.045). We found no statistically significant differences across the various types of constructs used. Intra-operative control of the acromioclavicular joint did not improve the result. Implantation of a biological graft significantly improved both the anatomical outcome in the vertical plane (p=0.04) and

  7. Patellofemoral Arthritis After Lateral Patellar Dislocation: A Matched Population-Based Analysis.

    PubMed

    Sanders, Thomas L; Pareek, Ayoosh; Johnson, Nicholas R; Stuart, Michael J; Dahm, Diane L; Krych, Aaron J

    2017-04-01

    The rate of patellofemoral arthritis after lateral patellar dislocation is unknown. Purpose/Hypothesis: The purpose of this study was to compare the risk of patellofemoral arthritis and knee arthroplasty between patients who experienced a lateral patellar dislocation and matched individuals without a patellar dislocation. Additionally, factors predictive of arthritis after patellar dislocation were examined. The hypothesis was that the rate of arthritis is likely higher among patients who experience a patellar dislocation compared with those who do not. Cohort study; Level of evidence, 3. In this study, 609 patients who had a first-time lateral patellar dislocation between 1990 and 2010 were compared with an age- and sex-matched cohort of patients who did not have a patellar dislocation. Medical records were reviewed to collect information related to the initial injury, recurrent dislocation, treatment, and progression to clinically significant patellofemoral arthritis (defined as symptoms with degenerative changes on patellar sunrise radiographs). Factors associated with arthritis (age, sex, recurrence, osteochondral injury, trochlear dysplasia) were examined. At a mean follow-up of 12.3 ± 6.5 years from initial dislocation, 58 patients (9.5%) in the dislocation cohort were diagnosed with patellofemoral arthritis, corresponding to a cumulative incidence of arthritis of 1.2% at 5 years, 2.7% at 10 years, 8.1% at 15 years, 14.8% at 20 years, and 48.9% at 25 years. In the control cohort, 8 patients (1.3%) were diagnosed with arthritis, corresponding to a cumulative incidence of arthritis of 0% at 5 years, 0% at 10 years, 1.3% at 15 years, 2.9% at 20 years, and 8.3% at 25 years. Therefore, patients who experienced a lateral patellar dislocation had a significantly higher risk of developing arthritis (hazard ratio [HR], 7.8; 95% CI, 3.9-17.6; P < .001) than individuals without a patellar dislocation. However, the risk of knee arthroplasty was similar between groups

  8. Transition of dislocation glide to shear transformation in shocked tantalum

    DOE PAGES

    Hsiung, Luke L.; Campbell, Geoffrey H.

    2017-02-28

    A TEM study of pure tantalum and tantalum-tungsten alloys explosively shocked at a peak pressure of 30 GPa (strain rate: ~1 x 10 4 sec -1) is presented. While no ω (hexagonal) phase was found in shock-recovered pure Ta and Ta-5W that contain mainly a low-energy cellular dislocation structure, shock-induced ω phase was found to form in Ta-10W that contains evenly distributed dislocations with a stored dislocation density higher than 1 x 10 12 cm -2. The TEM results clearly reveal that shock-induced α (bcc) → ω (hexagonal) shear transformation occurs when dynamic recovery reactions which lead the formation low-energymore » cellular dislocation structure become largely suppressed in Ta-10W shocked under dynamic (i.e., high strain-rate and high-pressure) conditions. A novel dislocation-based mechanism is proposed to rationalize the transition of dislocation glide to twinning and/or shear transformation in shock-deformed tantalum. Lastly, twinning and/or shear transformation take place as an alternative deformation mechanism to accommodate high-strain-rate straining when the shear stress required for dislocation multiplication exceeds the threshold shear stresses for twinning and/or shear transformation.« less

  9. Computational issues in the simulation of two-dimensional discrete dislocation mechanics

    NASA Astrophysics Data System (ADS)

    Segurado, J.; LLorca, J.; Romero, I.

    2007-06-01

    The effect of the integration time step and the introduction of a cut-off velocity for the dislocation motion was analysed in discrete dislocation dynamics (DD) simulations of a single crystal microbeam. Two loading modes, bending and uniaxial tension, were examined. It was found that a longer integration time step led to a progressive increment of the oscillations in the numerical solution, which would eventually diverge. This problem could be corrected in the simulations carried out in bending by introducing a cut-off velocity for the dislocation motion. This strategy (long integration times and a cut-off velocity for the dislocation motion) did not recover, however, the solution computed with very short time steps in uniaxial tension: the dislocation density was overestimated and the dislocation patterns modified. The different response to the same numerical algorithm was explained in terms of the nature of the dislocations generated in each case: geometrically necessary in bending and statistically stored in tension. The evolution of the dislocation density in the former was controlled by the plastic curvature of the beam and was independent of the details of the simulations. On the contrary, the steady-state dislocation density in tension was determined by the balance between nucleation of dislocations and those which are annihilated or which exit the beam. Changes in the DD imposed by the cut-off velocity altered this equilibrium and the solution. These results point to the need for detailed analyses of the accuracy and stability of the dislocation dynamic simulations to ensure that the results obtained are not fundamentally affected by the numerical strategies used to solve this complex problem.

  10. Grain size effects on dislocation and twinning mediated plasticity in magnesium

    DOE PAGES

    Fan, Haidong; Aubry, Sylvie; Arsenlis, Athanasios; ...

    2015-09-20

    Grain size effects on the competition between dislocation slip and {101¯2} -twinning in magnesium are investigated using discrete dislocation dynamics simulations. These simulations account for dislocation–twin boundary interactions and twin boundary migration through the glide of twinning dislocations. It is shown that twinning deformation exhibits a strong grain size effect; while dislocation mediated slip in untwinned polycrystals displays a weak one. In conclusion, this leads to a critical grain size at 2.7 μm, above which twinning dominates, and below which dislocation slip dominates.

  11. Prediction of dislocation generation during Bridgman growth of GaAs crystals

    NASA Technical Reports Server (NTRS)

    Tsai, C. T.; Yao, M. W.; Chait, Arnon

    1992-01-01

    Dislocation densities are generated in GaAs single crystals due to the excessive thermal stresses induced by temperature variations during growth. A viscoplastic material model for GaAs, which takes into account the movement and multiplication of dislocations in the plastic deformation, is developed according to Haasen's theory. The dislocation density is expressed as an internal state variable in this dynamic viscoplastic model. The deformation process is a nonlinear function of stress, strain rate, dislocation density and temperature. The dislocation density in the GaAs crystal during vertical Bridgman growth is calculated using a nonlinear finite element model. The dislocation multiplication in GaAs crystals for several temperature fields obtained from thermal modeling of both the GTE GaAs experimental data and artificially designed data are investigated.

  12. Prediction of dislocation generation during Bridgman growth of GaAs crystals

    NASA Astrophysics Data System (ADS)

    Tsai, C. T.; Yao, M. W.; Chait, Arnon

    1992-11-01

    Dislocation densities are generated in GaAs single crystals due to the excessive thermal stresses induced by temperature variations during growth. A viscoplastic material model for GaAs, which takes into account the movement and multiplication of dislocations in the plastic deformation, is developed according to Haasen's theory. The dislocation density is expressed as an internal state variable in this dynamic viscoplastic model. The deformation process is a nonlinear function of stress, strain rate, dislocation density and temperature. The dislocation density in the GaAs crystal during vertical Bridgman growth is calculated using a nonlinear finite element model. The dislocation multiplication in GaAs crystals for several temperature fields obtained from thermal modeling of both the GTE GaAs experimental data and artificially designed data are investigated.

  13. Microstructure of friction stir welded joints of 2017A aluminium alloy sheets.

    PubMed

    Mroczka, K; Dutkiewicz, J; Pietras, A

    2010-03-01

    The present study examines a friction stir welded 2017A aluminium alloy. Transmission electron microscope investigations of the weld nugget revealed the average grain size of 5 microm, moderate density of dislocations as well as the presence of nanometric precipitates located mostly in grains interiors. Scanning electron microscope observations of fractures showed the presence of ductile fracture in the region of the weld nugget with brittle precipitates in the lower part. The microhardness analysis performed on the cross-section of the joints showed fairly small changes; however, after the artificial ageing process an increase in hardness was observed. The change of the joint hardness subject to the ageing process indicates partial supersaturation in the material during friction stir welding and higher precipitation hardening of the joint.

  14. Crack Tip Dislocation Nucleation in FCC Solids

    NASA Astrophysics Data System (ADS)

    Knap, J.; Sieradzki, K.

    1999-02-01

    We present results of molecular dynamic simulations aimed at examining crack tip dislocation emission in fcc solids. The results are analyzed in terms of recent continuum formulations of this problem. In mode II, Au, Pd, and Pt displayed a new unanticipated mechanism of crack tip dislocation emission involving the creation of a pair of Shockley partials on a slip plane one plane below the crack plane. In mode I, for all the materials examined, Rice's continuum formulation [J. Mech. Phys. Solids 40, 239 (1992)] underestimated the stress intensity for dislocation emission by almost a factor of 2. Surface stress corrections to the emission criterion brought the agreement between continuum predictions and simulations to within 20%.

  15. Two-year follow-up evaluation of surgical treatment for thoracolumbar fracture-dislocation.

    PubMed

    Hao, Dingjun; Wang, Wentao; Duan, Kun; Ma, Minjie; Jiang, Yong; Liu, Tuanjiang; He, Baorong

    2014-10-01

    A randomized, controlled clinical trial. This randomized controlled clinical trial was aimed at comparing the clinical outcomes of combined posteroanterior (P-A) fusion and transforaminal thoracic interbody fusion (TTIF) in cases of thoracolumbar fracture-dislocation. The optimal treatment strategy for thoracolumbar fracture-dislocation remains controversial. Sixty-one patients presenting with acute fracture-dislocation of the thoracolumbar joint between March 2010 and December 2011 were enrolled and randomly assigned to the P-A or TTIF group. The radiological outcome was assessed by acquiring radiographs in the standing position and computed tomographic scans. The clinical outcome was measured in terms of the American Spinal Injury Association score, visual analogue scale score, and Oswestry Disability Index. Moreover, we assessed the severity of overall morbidity and morbidity at the donor site in the 2 patient groups. The Student t and χ tests were used for the analysis of independent variables and categorical data, respectively. Only 57 of the enrolled patients were available for the required 24-month follow-up period, 27 underwent TTIF and 30 underwent P-A fusion. Both treatments were similar with respect to the fusion rate, extent of decompression, loss of correction, rate of instrumentation failure, American Spinal Injury Association score, visual analogue scale score, and Oswestry Disability Index (P > 0.05). However, the blood loss, operating time, and rate of perioperative complications were greater in the P-A group than in the TTIF group (P < 0.05). The clinical and radiological outcomes were similar for both the treatment procedures. However, our findings suggest that TTIF allows for safe interbody fusion and circumferential decompression, requires only a posterior approach, and is associated with a lower incidence of surgery-related complications. 2.

  16. New method for revealing dislocations in garnet: premelting decoration

    NASA Astrophysics Data System (ADS)

    Liu, Xiangwen; Xie, Zhanjun; Jin, Zhenmin; Li, Zhuoyue; Ao, Ping; Wu, Yikun

    2018-05-01

    Premelting decoration (PMD) of dislocation experiments was carried out on garnets at 1 atmosphere pressure and temperatures of 800-1000 °C. Numerous decorated lines were observed on the polished surface of heat-treated garnet grains. The results of scanning electron microscopy, laser Raman spectroscopy and transmission electron microscopy (TEM) analyses indicate that these decorated lines were generated by premelting reaction along the dislocation lines and subgrain boundaries. The constituents of decorated lines on the polished surface of garnet are hematite, magnetite, and melt. While, in the interior of garnet, their constituents changed to Al-bearing magnetite and melt. The dislocation density of a gem-quality megacrystal garnet grain by means of the PMD is similar to that obtained by TEM, which confirms that the PMD is a new reliable method for revealing dislocations in garnet. This method greatly reduces the cost and time involved in the observation of dislocation microstructures in deformed garnet.

  17. Modeling of dislocation channel width evolution in irradiated metals

    NASA Astrophysics Data System (ADS)

    Doyle, Peter J.; Benensky, Kelsa M.; Zinkle, Steven J.

    2018-02-01

    Defect-free dislocation channel formation has been reported to promote plastic instability during tensile testing via localized plastic flow, leading to a distinct loss of ductility and strain hardening in many low-temperature irradiated materials. In order to study the underlying mechanisms governing dislocation channel width and formation, the channel formation process is modeled via a simple stochastic dislocation-jog process dependent upon grain size, defect cluster density, and defect size. Dislocations traverse a field of defect clusters and jog stochastically upon defect interaction, forming channels of low defect-density. Based upon prior molecular dynamics (MD) simulations and in-situ experimental transmission electron microscopy (TEM) observations, each dislocation encounter with a dislocation loop or stacking fault tetrahedron (SFT) is assumed to cause complete absorption of the defect cluster, prompting the dislocation to jog up or down by a distance equal to half the defect cluster diameter. Channels are predicted to form rapidly and are comparable to reported TEM measurements for many materials. Predicted channel widths are found to be most strongly dependent on mean defect size and correlated well with a power law dependence on defect diameter and density, and distance from the dislocation source. Due to the dependence of modeled channel width on defect diameter and density, maximum channel width is predicted to slowly increase as accumulated dose increases. The relatively weak predicted dependence of channel formation width with distance, in accordance with a diffusion analogy, implies that after only a few microns from the source, most channels observed via TEM analyses may not appear to vary with distance because of limitations in the field-of-view to a few microns. Further, examinations of the effect of the so-called "source-broadening" mechanism of channel formation showed that its effect is simply to add a minimum thickness to the channel

  18. [Intra-prosthetic dislocation of the Bousquet dual mobility socket].

    PubMed

    Lecuire, F; Benareau, I; Rubini, J; Basso, M

    2004-05-01

    The Bousquet system is a dual mobility head-polyethylene polyethylene-metal cup socket. The polyethylene insert retaining the femoral head moves in the noncemented metal cup, increasing both mobility and stability. Between 1989 and 1997, seven cases of intra-prosthetic dislocation (six patients) were observed. The femoral head escaped from the polyethylene insert due to wear. On the average, this complication occurred ten Years after implantation. Risk of dislocation was high in six of the seven hips. All patients had a large sized stem screwed into the femoral neck. There was a characteristic radiological aspect with loss of the concentric head metal cup configuration. The head was applied against the upper wall of the metal cup. Surgical replacement was undertaken early in six patients by simply changing the insert without modifying the other stable components. Outcome remained good at three to eight Years. One patient underwent late surgery. The insert and the cup were replaced with a classical implant. Functional outcome was good but recurrent dislocation occurred. At mid-term, intra-prosthetic dislocation of dual mobility sockets appears to be exceptional. Dislocation results from polyethylene wear leading to failure of the insert to retain the prosthetic head. Wear is favored by direct phenomena (direct contact between neck and insert which can occur early if there is a small difference in the head and neck diameters) or indirect phenomena (factors limiting polyethylene metal-cup mobility). Surgical treatment is necessary. If undertaken early, replacement with a modular head and insert can be sufficient if the prosthesis has not loosened but the metal cup may have to be replaced in the event of metal-metal contact between the head and the cup. Prosthesis loosening, wear of the metal cup, or an identified cause of dislocation imply replacing the failing implants. Implantation of the dual mobility system is particularly interesting for patients with a high risk

  19. The EIT- and N- joint resonance lineshape asymmetry

    NASA Astrophysics Data System (ADS)

    Crescimanno, Michael; Hancox, Cindy; Hohensee, Michael; Phillips, David; Walsworth, Ron

    2008-03-01

    The solution of a quantum optics model for the joint EIT- and N- resonance explains the experimentally observed two-photon lineshape asymmetry as arising from interference and AC stark effects. This solution is evaluated for various light field intensities, detunings and couplings associated with experiments performed on the D1 and D2 transition of 87Rb. Because of its contribution to clock instability, lineshape asymmetry remains perhaps the main impediment to improving all-optical time standards based on the joint resonance.

  20. Obesity: The Modifiable Risk Factor in Total Joint Arthroplasty.

    PubMed

    Bookman, Jared S; Schwarzkopf, Ran; Rathod, Parthiv; Iorio, Richard; Deshmukh, Ajit J

    2018-07-01

    Obesity is an epidemic in the health care system. Obesity poses several challenges and raises unique issues for the arthroplasty surgeon. Obese patients are at higher risk for infection and dislocation. Additionally, obese patients have poorer implant survivorship and functional scores postoperatively. Obesity is a modifiable risk factor and weight loss preoperatively should be strongly considered. Obese patients must be counseled so that they have realistic expectations after total joint arthroplasty. Copyright © 2018 Elsevier Inc. All rights reserved.

  1. [Triple no loop Endobutton plate combined with Orthcord line for the treatment of acromioclavicular dislocation of Tossy type III].

    PubMed

    Xia, Ming-Hua; Xie, Shui-Hua; Wu, Jun; Zhang, Wen-Qing; Chen, Wei-Dong; He, Jian-Hua; Ding, Hao; Hu, Qian-Qin; Wang, Xiao-Peng

    2016-07-25

    To explore the clinical effects of the triple no loop Endobutton plate combined with Orthcord line in treating acromioclavicular dislocation of Tossy type III. Between February 2011 and September 2013, 36 patients with acromioclavicular dislocation of Tossy type III were treated with triple no loop Endobutton plate and Orthcord line. There were 21 males and 15 females, aged from 9 to 48 years old with an average of (26.41±14.05) years. Couse of disease was from 2 to 7 days in the patients. The patients had the clinical manifestations such as shoulder pain, extension limited, acromioclavicular tenderness, positive organ point sign. Clinical effects were assessed by acromioclavicular scoring system. Thirty six patients were followed up from 8 to 15 months with an average of (12.2±4.3) months. All incisions got primary healing. At the final follow up, all shoulder pain vanished, acromioclavicular joints without tenderness, negative organ point sign. No redislocation and steel plate loosening were found. According to the acromioclavicular scoring system, 31 cases obtained excellent results, 5 good. The method of triple no loop Endobutton plate combined with Orthcord line for acromioclavicular dislocation of Tossy type III has advantage of less risk and complication, good functional rehabilitation and is an ideal method.

  2. Dislocation Strengthening without Ductility Trade-off in Metastable Austenitic Steels

    PubMed Central

    Liu, Jiabin; Jin, Yongbin; Fang, Xiaoyang; Chen, Chenxu; Feng, Qiong; Liu, Xiaowei; Chen, Yuzeng; Suo, Tao; Zhao, Feng; Huang, Tianlin; Wang, Hongtao; Wang, Xi; Fang, Youtong; Wei, Yujie; Meng, Liang; Lu, Jian; Yang, Wei

    2016-01-01

    Strength and ductility are mutually exclusive if they are manifested as consequence of the coupling between strengthening and toughening mechanisms. One notable example is dislocation strengthening in metals, which invariably leads to reduced ductility. However, this trend is averted in metastable austenitic steels. A one-step thermal mechanical treatment (TMT), i.e. hot rolling, can effectively enhance the yielding strength of the metastable austenitic steel from 322 ± 18 MPa to 675 ± 15 MPa, while retaining both the formability and hardenability. It is noted that no boundaries are introduced in the optimized TMT process and all strengthening effect originates from dislocations with inherited thermal stability. The success of this method relies on the decoupled strengthening and toughening mechanisms in metastable austenitic steels, in which yield strength is controlled by initial dislocation density while ductility is retained by the capability to nucleate new dislocations to carry plastic deformation. Especially, the simplicity in processing enables scaling and industrial applications to meet the challenging requirements of emissions reduction. On the other hand, the complexity in the underlying mechanism of dislocation strengthening in this case may shed light on a different route of material strengthening by stimulating dislocation activities, rather than impeding motion of dislocations. PMID:27739481

  3. Dislocation Strengthening without Ductility Trade-off in Metastable Austenitic Steels

    NASA Astrophysics Data System (ADS)

    Liu, Jiabin; Jin, Yongbin; Fang, Xiaoyang; Chen, Chenxu; Feng, Qiong; Liu, Xiaowei; Chen, Yuzeng; Suo, Tao; Zhao, Feng; Huang, Tianlin; Wang, Hongtao; Wang, Xi; Fang, Youtong; Wei, Yujie; Meng, Liang; Lu, Jian; Yang, Wei

    2016-10-01

    Strength and ductility are mutually exclusive if they are manifested as consequence of the coupling between strengthening and toughening mechanisms. One notable example is dislocation strengthening in metals, which invariably leads to reduced ductility. However, this trend is averted in metastable austenitic steels. A one-step thermal mechanical treatment (TMT), i.e. hot rolling, can effectively enhance the yielding strength of the metastable austenitic steel from 322 ± 18 MPa to 675 ± 15 MPa, while retaining both the formability and hardenability. It is noted that no boundaries are introduced in the optimized TMT process and all strengthening effect originates from dislocations with inherited thermal stability. The success of this method relies on the decoupled strengthening and toughening mechanisms in metastable austenitic steels, in which yield strength is controlled by initial dislocation density while ductility is retained by the capability to nucleate new dislocations to carry plastic deformation. Especially, the simplicity in processing enables scaling and industrial applications to meet the challenging requirements of emissions reduction. On the other hand, the complexity in the underlying mechanism of dislocation strengthening in this case may shed light on a different route of material strengthening by stimulating dislocation activities, rather than impeding motion of dislocations.

  4. Controllable Growth and Formation Mechanisms of Dislocated WS2 Spirals.

    PubMed

    Fan, Xiaopeng; Zhao, Yuzhou; Zheng, Weihao; Li, Honglai; Wu, Xueping; Hu, Xuelu; Zhang, Xuehong; Zhu, Xiaoli; Zhang, Qinglin; Wang, Xiao; Yang, Bin; Chen, Jianghua; Jin, Song; Pan, Anlian

    2018-06-13

    Two-dimensional (2D) layered metal dichalcogenides can form spiral nanostructures by a screw-dislocation-driven mechanism, which leads to changes in crystal symmetry and layer stackings that introduce attractive physical properties different from their bulk and few-layer nanostructures. However, controllable growth of spirals is challenging and their growth mechanisms are poorly understood. Here, we report the controllable growth of WS 2 spiral nanoplates with different stackings by a vapor phase deposition route and investigate their formation mechanisms by combining atomic force microscopy with second harmonic generation imaging. Previously not observed "spiral arm" features could be explained as covered dislocation spiral steps, and the number of spiral arms correlates with the number of screw dislocations initiated at the bottom plane. The supersaturation-dependent growth can generate new screw dislocations from the existing layers, or even new layers templated by existing screw dislocations. Different number of dislocations and orientation of new layers result in distinct morphologies, different layer stackings, and more complex nanostructures, such as triangular spiral nanoplates with hexagonal spiral pattern on top. This work provides the understanding and control of dislocation-driven growth of 2D nanostructures. These spiral nanostructures offer diverse candidates for probing the physical properties of layered materials and exploring new applications in functional nanoelectronic and optoelectronic devices.

  5. Dislocation Strengthening without Ductility Trade-off in Metastable Austenitic Steels.

    PubMed

    Liu, Jiabin; Jin, Yongbin; Fang, Xiaoyang; Chen, Chenxu; Feng, Qiong; Liu, Xiaowei; Chen, Yuzeng; Suo, Tao; Zhao, Feng; Huang, Tianlin; Wang, Hongtao; Wang, Xi; Fang, Youtong; Wei, Yujie; Meng, Liang; Lu, Jian; Yang, Wei

    2016-10-14

    Strength and ductility are mutually exclusive if they are manifested as consequence of the coupling between strengthening and toughening mechanisms. One notable example is dislocation strengthening in metals, which invariably leads to reduced ductility. However, this trend is averted in metastable austenitic steels. A one-step thermal mechanical treatment (TMT), i.e. hot rolling, can effectively enhance the yielding strength of the metastable austenitic steel from 322 ± 18 MPa to 675 ± 15 MPa, while retaining both the formability and hardenability. It is noted that no boundaries are introduced in the optimized TMT process and all strengthening effect originates from dislocations with inherited thermal stability. The success of this method relies on the decoupled strengthening and toughening mechanisms in metastable austenitic steels, in which yield strength is controlled by initial dislocation density while ductility is retained by the capability to nucleate new dislocations to carry plastic deformation. Especially, the simplicity in processing enables scaling and industrial applications to meet the challenging requirements of emissions reduction. On the other hand, the complexity in the underlying mechanism of dislocation strengthening in this case may shed light on a different route of material strengthening by stimulating dislocation activities, rather than impeding motion of dislocations.

  6. Dislocation Multiplication in the Early Stage of Deformation in Mo Single Crystals

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Hsiung, L.; Lassila, D.H.

    Initial dislocation structure in annealed high-purity Mo single crystals and deformation substructure in a crystal subjected to 1% compression have been examined and studied using transmission electron microscopy (TEM) techniques in order to investigate dislocation multiplication mechanisms in the early stage of plastic deformation. The initial dislocation density is in a range of 10{sup 6} {approx} 10{sup 7} cm{sup -2}, and the dislocation structure is found to contain many grown-in superjogs along dislocation lines. The dislocation density increases to a range of 10{sup 8} {approx} 10{sup 9} cm{sup -2}, and the average jog height is also found to increase aftermore » compressing for a total strain of 1%. It is proposed that the preexisting jogged screw dislocations can act as (multiple) dislocation multiplication sources when deformed under quasi-static conditions. The jog height can increase by stress-induced jog coalescence, which takes place via the lateral migration (drift) of superjogs driven by unbalanced line-tension partials acting on link segments of unequal lengths. The coalescence of superjogs results in an increase of both link length and jog height. Applied shear stress begins to push each link segment to precede dislocation multiplication when link length and jog height are greater than critical lengths. This ''dynamic'' dislocation multiplication source is suggested to be crucial for the dislocation multiplication in the early stage of plastic deformation in Mo.« less

  7. A phase field dislocation dynamics model for a bicrystal interface system: An investigation into dislocation slip transmission across cube-on-cube interfaces

    DOE PAGES

    Zeng, Y.; Hunter, A.; Beyerlein, I. J.; ...

    2015-09-14

    In this study, we present a phase field dislocation dynamics formulation designed to treat a system comprised of two materials differing in moduli and lattice parameters that meet at a common interface. We apply the model to calculate the critical stress τ crit required to transmit a perfect dislocation across the bimaterial interface with a cube-on-cube orientation relationship. The calculation of τ crit accounts for the effects of: 1) the lattice mismatch (misfit or coherency stresses), 2) the elastic moduli mismatch (Koehler forces or image stresses), and 3) the formation of the residual dislocation in the interface. Our results showmore » that the value of τ crit associated with the transmission of a dislocation from material 1 to material 2 is not the same as that from material 2 to material 1. Dislocation transmission from the material with the lower shear modulus and larger lattice parameter tends to be easier than the reverse and this apparent asymmetry in τ crit generally increases with increases in either lattice or moduli mismatch or both. In efforts to clarify the roles of lattice and moduli mismatch, we construct an analytical model for τcrit based on the formation energy of the residual dislocation. We show that path dependence in this energetic barrier can explain the asymmetry seen in the calculated τ crit values.« less

  8. Symposium introduction: the first joint American Chemical Society Agricultural and Food Chemistry Division and the American Chemical Society International Chemical Sciences Chapter in Thailand

    USDA-ARS?s Scientific Manuscript database

    The American Chemical Society (ACS) Agricultural and Food Chemistry Division (AGFD) and the ACS International Chemical Sciences Chapter in Thailand (ICSCT) worked together to stage the “1st Joint ACS AGFD - ACS ICSCT Symposium on Agricultural and Food Chemistry,” which was held in Bangkok, Thailand ...

  9. A new surgical technique for traumatic dislocation of posterior tibial tendon with avulsion fracture of medial malleolus.

    PubMed

    Jeong, Soon-Taek; Hwang, Sun-Chul; Kim, Dong-Hee; Nam, Dae-Cheol

    2015-01-01

    We introduce a case of traumatic dislocation of the posterior tibial tendon with avulsion fracture of the medial malleolus in a 52-year-old female patient who was treated surgically with periosteal flap and suture anchor fixation. Based in the posteromedial ridge of the distal tibia, a quadrilateral periosteal flap was created and folded over the tendon, followed by fixation on the lateral aspect of the groove by use of multiple suture anchors. Clinical and radiological findings 25 months postoperatively showed well-preserved function of the ankle joint with stable tendon gliding.

  10. Computational study of dislocation based mechanisms in FCC materials

    NASA Astrophysics Data System (ADS)

    Yellakara, Ranga Nikhil

    Understanding the relationships between microstructures and properties of materials is a key to developing new materials with more suitable qualities or employing the appropriate materials in special uses. In the present world of material research, the main focus is on microstructural control to cost-effectively enhance properties and meet performance specifications. This present work is directed towards improving the fundamental understanding of the microscale deformation mechanisms and mechanical behavior of metallic alloys, particularly focusing on face centered cubic (FCC) structured metals through a unique computational methodology called three-dimensional dislocation dynamics (3D-DD). In these simulations, the equations of motion for dislocations are mathematically solved to determine the evolution and interaction of dislocations. Microstructure details and stress-strain curves are a direct observation in the simulation and can be used to validate experimental results. The effect of initial dislocation microstructure on the yield strength has been studied. It has been shown that dislocation density based crystal plasticity formulations only work when dislocation densities/numbers are sufficiently large so that a statistically accurate description of the microstructure can be obtainable. The evolution of the flow stress for grain sizes ranging from 0.5 to 10 mum under uniaxial tension was simulated using an improvised model by integrating dislocation pile-up mechanism at grain boundaries has been performed. This study showed that for a same initial dislocation density, the Hall--Petch relationship holds well at small grain sizes (0.5--2 mum), beyond which the yield strength remains constant as the grain size increases. Various dislocation-particle interaction mechanisms have been introduced and investigations were made on their effect on the uniaxial tensile properties. These studies suggested that increase in particle volume fraction and decrease in particle

  11. Dislocation Structure and Mobility in hcp He 4

    DOE PAGES

    Landinez Borda, Edgar Josue; Cai, Wei; de Koning, Maurice

    2016-07-20

    We assess the core structure and mobility of the screw and edge basal-plane dislocations in hcp 4He using path-integral Monte Carlo simulations. Our findings provide key insights into recent interpretations of giant plasticity and mass flow junction experiments. First, both dislocations are dissociated into nonsuperfluid Shockley partial dislocations separated by ribbons of stacking fault, suggesting that they are unlikely to act as one-dimensional channels that may display Lüttinger-liquid-like behavior. Second, the centroid positions of the partial cores are found to fluctuate substantially, even in the absence of applied shear stresses. This implies that the lattice resistance to motion of themore » partial dislocations is negligible, consistent with the recent experimental observations of giant plasticity. Our results indicate that both the structure of the partial cores and the zero-point fluctuations play a role in this extreme mobility.« less

  12. Milch versus Stimson technique for nonsedated reduction of anterior shoulder dislocation: a prospective randomized trial and analysis of factors affecting success.

    PubMed

    Amar, Eyal; Maman, Eran; Khashan, Morsi; Kauffman, Ehud; Rath, Ehud; Chechik, Ofir

    2012-11-01

    The shoulder is regarded as the most commonly dislocated major joint in the human body. Most dislocations can be reduced by simple methods in the emergency department, whereas others require more complicated approaches. We compared the efficacy, safety, pain, and duration of the reduction between the Milch technique and the Stimson technique in treating dislocations. We also identified factors that affected success rate. All enrolled patients were randomized to either the Milch technique or the Stimson technique for dislocated shoulder reduction. The study cohort consisted of 60 patients (mean age, 43.9 years; age range, 18-88 years) who were randomly assigned to treatment by either the Stimson technique (n = 25) or the Milch technique (n = 35). Oral analgesics were available for both groups. The 2 groups were similar in demographics, patient characteristics, and pain levels. The first reduction attempt in the Milch and Stimson groups was successful in 82.8% and 28% of cases, respectively (P < .001), and the mean reduction time was 4.68 and 8.84 minutes, respectively (P = .007). The success rate was found to be affected by the reduction technique, the interval between dislocation occurrence and first reduction attempt, and the pain level on admittance. The success rate and time to achieve reduction without sedation were superior for the Milch technique compared with the Stimson technique. Early implementation of reduction measures and low pain levels at presentation favor successful reduction, which--in combination with oral pain medication--constitutes an acceptable and reasonable management alternative to reduction with sedation. Copyright © 2012 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Mosby, Inc. All rights reserved.

  13. Strength and Dislocation Structure Evolution of Small Metals under Vibrations

    NASA Astrophysics Data System (ADS)

    Ngan, Alfonso

    2015-03-01

    It is well-known that ultrasonic vibration can soften metals, and this phenomenon has been widely exploited in industrial applications concerning metal forming and bonding. In this work, we explore the effects of a superimposed small oscillatory load on metal plasticity, from the nano- to macro-size range, and from audible to ultrasonic frequency ranges. Macroscopic and nano-indentation were performed on aluminum, copper and molybdenum, and the results show that the simultaneous application of oscillatory stresses can lower the hardness of these samples. More interestingly, EBSD and TEM observations show that subgrain formation and reduction in dislocation density generally occurred when stress oscillations were applied. These findings point to an important knowledge gap in metal plasticity - the existing understanding of ultrasound softening in terms of the vibrations either imposing additional stress waves to augment the quasi-static applied load, or heating up the metal, whereas the metal's intrinsic deformation resistance or dislocation interactive processes are assumed unaltered by the ultrasound, is proven wrong by the present results. Furthermore, in the case of nanoindentation, the Continuous Stiffness Measurement technique for contact stiffness measurement assumes that the imposed signal-carrier oscillations do not intrinsically alter the material properties of the specimen, and again, the present results prove that this can be wrong. To understand the enhanced subgrain formation and dislocation annihilation, Discrete Dislocation Dynamics (DDD) simulations were carried out and these show that when an oscillatory stress is superimposed on a quasi-static applied stress, reversals of motion of dislocations may occur, and these allow the dislocations to revisit repeatedly suitable configurations for annihilation. DDD, however, was unable to predict the observed subgrain formation presumably because the number of dislocations that can be handled is not large

  14. [Stable ankle joint fractures. Indication for surgical or conservative management?].

    PubMed

    Richter, J; Schulze, W; Muhr, G

    1999-06-01

    In German literature, ankle joint fractures are mostly classified in three groups according to Weber. In cases of the type A, the fracture line runs below, in cases of type B at height of the syndesmotic ligaments. C-type fractures are typically seen above this region. However, this practical and simple classification allows no inferences at accompanying injuries which in turn influence the functional outcome. We observed isolated fractures of the lateral malleolus in more than 60% of all type B-fractures, as soon as in the majority the type A-fractures. Since isolated medial ankle fractures occur very rarely, careful exclusion of further injuries is advisable here. In order to differentiate stable ones from unstable type B ankle injuries, we carry out a manual stress test, if there is less than 2 mm fracture dislocation and a congruent ankle mortise. In this manner we could find that stable lateral ankle fractures are characterized with a combination of an intact dorsal syndesmotic and medial ligament. Stable type B and undisplaced type A fractures were treated conservatively with an ankle brace (Aircast?). Unstable ankle injuries were treated by ORIF. Conservative treatment for undisplaced medial malleolar fractures is recommended, if x-rays showed less than 2 mm dislocation which allows a tibio-talare impingement. Biomechanical investigations could prove a significant increase in ankle joint stability, when an axial load of 300 N was applied to various horizontal loads. The talus does not follow automatically a displaced fibular fracture. The dorsal syndesmotic and the medial deltoid ligaments control ankle joint stability.

  15. Modeling collective behavior of dislocations in crystalline materials

    NASA Astrophysics Data System (ADS)

    Varadhan, Satya N.

    Elastic interaction of dislocations leads to collective behavior and determines plastic response at the mesoscale. Notable characteristics of mesoscale plasticity include the formation of dislocation patterns, propagative instability phenomena due to strain aging such as the Luders and Portevin-Le Chatelier effects, and size-dependence of low stress. This work presents a unified approach to modeling collective behavior based on mesoscale field dislocation mechanics and crystal plasticity, using constitutive models with physical basis. Successful application is made to: compression of a bicrystal, where "smaller is stronger"---the flow stress increases as the specimen size is reduced; torsional creep of ice single crystals, where the plastic strain rate increases with time under constant applied torque; strain aging in a single crystal alloy, where the transition from homogeneous deformation to intermittent bands to continuous band is captured as the applied deformation rate is increased. A part of this work deals with the kinematics of dislocation density evolution. An explicit Galerkin/least-squares formulation is introduced for the quasilinear evolution equation, which leads to a symmetric and well-conditioned system of equations with constant coefficients, making it attractive for large-scale problems. It is shown that the evolution equation simplifies to the Hamilton-Jacobi equations governing geometric optics and level set methods in the following physical contexts: annihilation of dislocations, expansion of a polygonal dislocation loop and operation of a Frank-Read source. The weak solutions to these equations are not unique, and the numerical method is able to capture solutions corresponding to shock as well as expansion fans.

  16. Edge-on dislocation loop in anisotropic hcp zirconium thin foil

    NASA Astrophysics Data System (ADS)

    Wu, Wenwang; Xia, Re; Qian, Guian; Xu, Shucai; Zhang, Jinhuan

    2015-10-01

    Edge-on dislocation loops with 〈 a 〉 -type and 〈 c 〉 -type of Burgers vectors can be formed on prismatic or basel habit planes of hexagonal close-packed (hcp) zirconium alloys during in-situ ion irradiation and neutron irradiation experiments. In this work, an anisotropic image stress method was employed to analyze the free surface effects of dislocation loops within hcp Zr thin foils. Calculation results demonstrate that image stress has a remarkable effect on the distortion fields of dislocation loops within infinite medium, and the image energy becomes remarkable when dislocation loops are situated close to the free surfaces. Moreover, image forces of the 1 / 2 〈 0001 〉 (0001) dislocation loop within (0001) thin foil is much stronger than that of the 1 / 3 〈 11 2 bar 0 〉 (11 2 bar 0) dislocation loop within (11 2 bar 0) thin foil of identical geometrical configurations. Finally, image stress effect on the physical behaviors of loops during in-situ ion irradiation experiments is discussed.

  17. Investigation of dislocation cluster evolution during directional solidification of multicrystalline silicon

    NASA Astrophysics Data System (ADS)

    Oriwol, Daniel; Trempa, Matthias; Sylla, Lamine; Leipner, Hartmut S.

    2017-04-01

    Dislocation clusters are the main crystal defects in multicrystalline silicon and are detrimental for solar cell efficiency. They were formed during the silicon ingot casting due to the relaxation of strain energy. The evolution of the dislocation clusters was studied by means of automated analysing tools of the standard wafer and cell production giving information about the cluster development as a function of the ingot height. Due to the observation of the whole wafer surface the point of view is of macroscopic nature. It was found that the dislocations tend to build clusters of high density which usually expand in diameter as a function of ingot height. According to their structure the dislocation clusters can be divided into light and dense clusters. The appearance of both types shows a clear dependence on the orientation of the grain growth direction. Additionally, a process of annihilation of dislocation clusters during the crystallization has been observed. To complement the macroscopic description, the dislocation clusters were also investigates by TEM. It is shown that the dislocations within the subgrain boundaries are closely arranged. Distances of 40-30 nm were found. These results lead to the conclusion that the dislocation density within the cluster structure is impossible to quantify by means of etch pit counting.

  18. Dislocation mechanism based model for stage II fatigue crack propagation rate

    NASA Technical Reports Server (NTRS)

    Mazumdar, P. K.

    1986-01-01

    Repeated plastic deformation, which of course depends on dislocation mechanism, at or near the crack tip leads to the fatigue crack propagation. By involving the theory of thermally activated flow and the cumulative plastic strain criterion, an effort is made here to model the stage II fatigue crack propagation rate in terms of the dislocation mechanism. The model, therefore, provides capability to ascertain: (1) the dislocation mechanism (and hence the near crack tip microstructures) assisting the crack growth, (2) the relative resistance of dislocation mechanisms to the crack growth, and (3) the fracture surface characteristics and its interpretation in terms of the dislocation mechanism. The local microstructure predicted for the room temperature crack growth in copper by this model is in good agreement with the experimental results taken from the literature. With regard to the relative stability of such dislocation mechanisms as the cross-slip and the dislocation intersection, the model suggests an enhancement of crack growth rate with an ease of cross-slip which in general promotes dislocation cell formation and is common in material which has high stacking fault energy (produces wavy slips). Cross-slip apparently enhances crack growth rate by promoting slip irreversibility and fracture surface brittleness to a greater degree.

  19. Bilateral posterior fracture-dislocation of the shoulder: Report of two cases

    PubMed Central

    Claro, Rui; Sousa, Ricardo; Massada, Marta; Ramos, Joaquim; Lourenço, José M.

    2009-01-01

    Bilateral posterior fracture-dislocation of the shoulder is a very rare injury. Almost 50% of bilateral posterior dislocations are due to a convulsive seizure, rising to 90% if the dislocations are associated with fractures. Electric shock accounts for less than 5% of bilateral posterior dislocations of the shoulder. A systematization of the clinical and radiological approach, followed by an early diagnosis and proper surgical treatment is essential. Authors report 2 cases of bilateral posterior fracture-dislocation of the shoulder, one caused by a convulsive seizure and the other by an electric shock. A review of literature and a treatment protocol are also presented. PMID:20661400

  20. Multiphysical simulation analysis of the dislocation structure in germanium single crystals

    NASA Astrophysics Data System (ADS)

    Podkopaev, O. I.; Artemyev, V. V.; Smirnov, A. D.; Mamedov, V. M.; Sid'ko, A. P.; Kalaev, V. V.; Kravtsova, E. D.; Shimanskii, A. F.

    2016-09-01

    To grow high-quality germanium crystals is one of the most important problems of growth industry. The dislocation density is an important parameter of the quality of single crystals. The dislocation densities in germanium crystals 100 mm in diameter, which have various shapes of the side surface and are grown by the Czochralski technique, are experimentally measured. The crystal growth is numerically simulated using heat-transfer and hydrodynamics models and the Alexander-Haasen dislocation model in terms of the CGSim software package. A comparison of the experimental and calculated dislocation densities shows that the dislocation model can be applied to study lattice defects in germanium crystals and to improve their quality.

  1. Neglected Posterior Dislocation of Hip in Children - A Case Report.

    PubMed

    Pal, Chandra Prakash; Kumar, Deepak; Sadana, Ashwani; Dinkar, Karuna Shankar

    2014-01-01

    Traumatic dislocation of the hip in children is a rare injury. We report the outcome of 2 patients of neglected hip dislocation which were treated by open reduction and internal fixation by k-wires. We treat 2 children both girls (one was of 4 years and other was 7 years of age). In both cases dislocation was unilateral and was not associated with any facture. Both cases were of posterior dislocation. in both cases open reduction and internal fixation was done by k wires. Hip spica was applied post operatively in both cases. The k wire was removed at 3 to 4 weeks. Patients were allowed to bear weight from gradual to full weight bearing after 6 weeks. We conclude that open reduction is a satisfactory treatment for neglected hip dislocation. It prevents not only deformity but also maintains limb length.

  2. A Comparison of Starting Wages and Job Satisfaction for Reemployed Dislocated Workers Participating in the Rock County Dislocated Worker Program.

    ERIC Educational Resources Information Center

    Borremans, Robert T.

    Following the economic recession of the early 1980's and the consequent high levels of unemployment in Rock County, a program was created at the Blackhawk Technical Institute (BTI) to assist dislocated workers reentering the labor force. The Rock County Dislocated Worker Program was intended as a comprehensive program with two principal activities…

  3. Dislocation-Twin Boundary Interactions Induced Nanocrystalline via SPD Processing in Bulk Metals

    NASA Astrophysics Data System (ADS)

    Zhang, Fucheng; Feng, Xiaoyong; Yang, Zhinan; Kang, Jie; Wang, Tiansheng

    2015-03-01

    This report investigated dislocation-twin boundary (TB) interactions that cause the TB to disappear and turn into a high-angle grain boundary (GB). The evolution of the microstructural characteristics of Hadfield steel was shown as a function of severe plastic deformation processing time. Sessile Frank partial dislocations and/or sessile unit dislocations were formed on the TB through possible dislocation reactions. These reactions induced atomic steps on the TB and led to the accumulation of gliding dislocations at the TB, which resulted in the transition from coherent TB to incoherent GB. The factors that affect these interactions were described, and a physical model was established to explain in detail the feasible dislocation reactions at the TB.

  4. Dislocation-twin boundary interactions induced nanocrystalline via SPD processing in bulk metals.

    PubMed

    Zhang, Fucheng; Feng, Xiaoyong; Yang, Zhinan; Kang, Jie; Wang, Tiansheng

    2015-03-11

    This report investigated dislocation-twin boundary (TB) interactions that cause the TB to disappear and turn into a high-angle grain boundary (GB). The evolution of the microstructural characteristics of Hadfield steel was shown as a function of severe plastic deformation processing time. Sessile Frank partial dislocations and/or sessile unit dislocations were formed on the TB through possible dislocation reactions. These reactions induced atomic steps on the TB and led to the accumulation of gliding dislocations at the TB, which resulted in the transition from coherent TB to incoherent GB. The factors that affect these interactions were described, and a physical model was established to explain in detail the feasible dislocation reactions at the TB.

  5. A discrete dislocation dynamics model of creeping single crystals

    NASA Astrophysics Data System (ADS)

    Rajaguru, M.; Keralavarma, S. M.

    2018-04-01

    Failure by creep is a design limiting issue for metallic materials used in several high temperature applications. Current theoretical models of creep are phenomenological with little connection to the underlying microscopic mechanisms. In this paper, a bottom-up simulation framework based on the discrete dislocation dynamics method is presented for dislocation creep aided by the diffusion of vacancies, known to be the rate controlling mechanism at high temperature and stress levels. The time evolution of the creep strain and the dislocation microstructure in a periodic unit cell of a nominally infinite single crystal is simulated using the kinetic Monte Carlo method, together with approximate constitutive laws formulated for the rates of thermal activation of dislocations over local pinning obstacles. The deformation of the crystal due to dislocation glide between individual thermal activation events is simulated using a standard dislocation dynamics algorithm, extended to account for constant stress periodic boundary conditions. Steady state creep conditions are obtained in the simulations with the predicted creep rates as a function of stress and temperature in good agreement with experimentally reported values. Arrhenius scaling of the creep rates as a function of temperature and power-law scaling with the applied stress are also reproduced, with the values of the power-law exponents in the high stress regime in good agreement with experiments.

  6. Dislocation Ledge Sources: Dispelling the Myth of Frank-Read Source Importance

    NASA Astrophysics Data System (ADS)

    Murr, L. E.

    2016-12-01

    In the early 1960s, J.C.M. Li questioned the formation of dislocation pileups at grain boundaries, especially in high-stacking-fault free-energy fcc metals and alloys, and proposed grain boundary ledge sources for dislocations in contrast to Frank -Read sources. This article reviews these proposals and the evolution of compelling evidence for grain boundary or related interfacial ledge sources of dislocations in metals and alloys, including unambiguous observations using transmission electron microscopy. Such observations have allowed grain boundary ledge source emission profiles of dislocations to be quantified in 304 stainless steel (with a stacking-fault free energy of 23 mJ/m2) and nickel (with a stacking-fault free energy of 128 mJ/m2) as a function of engineering strain. The evidence supports the conclusion that FR dislocation sources are virtually absent in metal and alloy deformation with ledges at interfaces dominating as dislocation sources.

  7. What Are the Risk Factors for Dislocation of Hip Bipolar Hemiarthroplasty Through the Anterolateral Approach? A Nested Case-control Study.

    PubMed

    Li, Lianhua; Ren, Jixin; Liu, Jia; Wang, Hao; Sang, Qinghua; Liu, Zhi; Sun, Tiansheng

    2016-12-01

    or dissociation were performed to estimate hazard rates (HRs) and corresponding 95% CIs with covariates of a probability less than 0.1 in univariate analysis. In this cohort, there were 26 dislocations including four that were also dissociations. The proportion of patients experiencing a dislocation was 6% (26 of 424). The mean interval from surgery to dislocation was 56 weeks (range, 0-433 weeks), and 18 dislocations (69%) occurred within 3 months after surgery. Three variables were independently associated with an increased risk of hip dislocation: dementia (HR, 3.51; 95% CI, 1.19-10.38; p = 0.02), discrepancy of offset (HR, 1.72; 95% CI, 1.15-2.58; p = 0.008), and lower MMSE score (HR, 0.93; 95% CI, 0.88-0.98; p = 0.007). The proportion of patients experiencing a dissociation was 0.9% (four of 424). The result of conditional logistic regression for dissociation showed that cup size smaller than 43 mm was the risk factor (HR = 513.05). However, there was no statistical difference with the probability equaling 0.47. After the anterolateral approach for treatment of femoral neck fracture using bipolar hemiarthroplasty, 6% of hips dislocated and 0.9% experienced dissociation. Cognitive dysfunction and discrepancy of offset were independent risk factors associated with an increased risk of prosthetic dislocation. The small cup without a safety ring may be the risk factor of dissociation. Discrepancy of offset should be avoided during the operation by performing an accurate femoral osteotomy and choosing an adequate femoral stem neck length. For patients with cognitive dysfunction and a small cup, suturing the joint capsule during the operation and reinforcing protective measures after surgery might reduce the occurrence of dislocation and dissociation, however a study addressing this is necessary to confirm this. Level III, therapeutic study.

  8. Study of the dislocation contribution to the internal friction background of gold

    NASA Astrophysics Data System (ADS)

    Baur, J.; Benoit, W.

    1987-04-01

    The dislocation contribution to the internal friction (IF) background is studied in annealed gold samples containing various dilute concentrations of platinum impurities. The measurements are performed in the kHz frequency range in order to determine the loss mechanism responsible for the high IF background observed at these low frequencies. To this end, the IF background was systematically measured as a function of frequency, vibration amplitude, temperature, and impurity concentration. The experimental results show that the high dislocation contribution observed in annealed samples is strain-amplitude independent for amplitudes in the range 10-7 to 2×10-6, but rapidly decreases for amplitudes smaller than 10-7. In particular, the dislocation contribution tends to zero when the strain amplitude tends to zero. Furthermore, this contribution is frequency independent. These observations demonstrate that the dislocation contribution cannot be explained by relaxations. In particular, this contribution cannot be attributed to a viscous damping of the dislocation motion. On the contrary, the experiments show that the IF background due to dislocations must be explained by hysteretic and athermal motions of dislocations interacting with point defects. However, these hysteretic motions are not due to breakaway of dislocations from pinning points distributed along their length. The experimental results can be explained by the presence of point defects close to the dislocations, but not on them. The mechanical energy loss is attributed to hysteretic motions of dislocations between potential minima created by point defects.

  9. Modeling of dislocation channel width evolution in irradiated metals

    DOE PAGES

    Doyle, Peter J.; Benensky, Kelsa M.; Zinkle, Steven J.

    2017-11-08

    Defect-free dislocation channel formation has been reported to promote plastic instability during tensile testing via localized plastic flow, leading to a distinct loss of ductility and strain hardening in many low-temperature irradiated materials. In order to study the underlying mechanisms governing dislocation channel width and formation, the channel formation process is modeled via a simple stochastic dislocation-jog process dependent upon grain size, defect cluster density, and defect size. Dislocations traverse a field of defect clusters and jog stochastically upon defect interaction, forming channels of low defect-density. And based upon prior molecular dynamics (MD) simulations and in-situ experimental transmission electron microscopymore » (TEM) observations, each dislocation encounter with a dislocation loop or stacking fault tetrahedron (SFT) is assumed to cause complete absorption of the defect cluster, prompting the dislocation to jog up or down by a distance equal to half the defect cluster diameter. Channels are predicted to form rapidly and are comparable to reported TEM measurements for many materials. Predicted channel widths are found to be most strongly dependent on mean defect size and correlated well with a power law dependence on defect diameter and density, and distance from the dislocation source. Due to the dependence of modeled channel width on defect diameter and density, maximum channel width is predicted to slowly increase as accumulated dose increases. The relatively weak predicted dependence of channel formation width with distance, in accordance with a diffusion analogy, implies that after only a few microns from the source, most channels observed via TEM analyses may not appear to vary with distance because of limitations in the field-of-view to a few microns. Furthermore, examinations of the effect of the so-called “source-broadening” mechanism of channel formation showed that its effect is simply to add a minimum thickness

  10. Modeling of dislocation channel width evolution in irradiated metals

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Doyle, Peter J.; Benensky, Kelsa M.; Zinkle, Steven J.

    Defect-free dislocation channel formation has been reported to promote plastic instability during tensile testing via localized plastic flow, leading to a distinct loss of ductility and strain hardening in many low-temperature irradiated materials. In order to study the underlying mechanisms governing dislocation channel width and formation, the channel formation process is modeled via a simple stochastic dislocation-jog process dependent upon grain size, defect cluster density, and defect size. Dislocations traverse a field of defect clusters and jog stochastically upon defect interaction, forming channels of low defect-density. And based upon prior molecular dynamics (MD) simulations and in-situ experimental transmission electron microscopymore » (TEM) observations, each dislocation encounter with a dislocation loop or stacking fault tetrahedron (SFT) is assumed to cause complete absorption of the defect cluster, prompting the dislocation to jog up or down by a distance equal to half the defect cluster diameter. Channels are predicted to form rapidly and are comparable to reported TEM measurements for many materials. Predicted channel widths are found to be most strongly dependent on mean defect size and correlated well with a power law dependence on defect diameter and density, and distance from the dislocation source. Due to the dependence of modeled channel width on defect diameter and density, maximum channel width is predicted to slowly increase as accumulated dose increases. The relatively weak predicted dependence of channel formation width with distance, in accordance with a diffusion analogy, implies that after only a few microns from the source, most channels observed via TEM analyses may not appear to vary with distance because of limitations in the field-of-view to a few microns. Furthermore, examinations of the effect of the so-called “source-broadening” mechanism of channel formation showed that its effect is simply to add a minimum thickness

  11. Surface stress mediated image force and torque on an edge dislocation

    NASA Astrophysics Data System (ADS)

    Raghavendra, R. M.; Divya, Iyer, Ganesh; Kumar, Arun; Subramaniam, Anandh

    2018-07-01

    The proximity of interfaces gives prominence to image forces experienced by dislocations. The presence of surface stress alters the traction-free boundary conditions existing on free-surfaces and hence is expected to alter the magnitude of the image force. In the current work, using a combined simulation of surface stress and an edge dislocation in a semi-infinite body, we evaluate the configurational effects on the system. We demonstrate that if the extra half-plane of the edge dislocation is parallel to the surface, the image force (glide) is not altered due to surface stress; however, the dislocation experiences a torque. The surface stress breaks the 'climb image force' symmetry, thus leading to non-equivalence between positive and negative climb. We discover an equilibrium position for the edge dislocation in the positive 'climb geometry', arising due to a competition between the interaction of the dislocation stress fields with the surface stress and the image dislocation. Torque in the climb configuration is not affected by surface stress (remains zero). Surface stress is computed using a recently developed two-scale model based on Shuttleworth's idea and image forces using a finite element model developed earlier. The effect of surface stress on the image force and torque experienced by the dislocation monopole is analysed using illustrative 3D models.

  12. Displacement field for an edge dislocation in a layered half-space

    USGS Publications Warehouse

    Savage, J.C.

    1998-01-01

    The displacement field for an edge dislocation in an Earth model consisting of a layer welded to a half-space of different material is found in the form of a Fourier integral following the method given by Weeks et al. [1968]. There are four elementary solutions to be considered: the dislocation is either in the half-space or the layer and the Burgers vector is either parallel or perpendicular to the layer. A general two-dimensional solution for a dip-slip faulting or dike injection (arbitrary dip) can be constructed from a superposition of these elementary solutions. Surface deformations have been calculated for an edge dislocation located at the interface with Burgers vector inclined 0??, 30??, 60??, and 90?? to the interface for the case where the rigidity of the layer is half of that of the half-space and the Poisson ratios are the same. Those displacement fields have been compared to the displacement fields generated by similarly situated edge dislocations in a uniform half-space. The surface displacement field produced by the edge dislocation in the layered half-space is very similar to that produced by an edge dislocation at a different depth in a uniform half-space. In general, a low-modulus (high-modulus) layer causes the half-space equivalent dislocation to appear shallower (deeper) than the actual dislocation in the layered half-space.

  13. Dislocation Processes and Frictional Stability of Faults

    NASA Astrophysics Data System (ADS)

    Toy, V. G.; Mitchell, T. M.; Druiventak, A.

    2011-12-01

    The rate dependence of frictional processes in faults in quartzofeldspathic crust is proposed to change at c. 300°C, because above this temperature asperity deformation can be accommodated by crystal plastic processes. As a consequence, the real fault contact area increases and the fault velocity strengthens. Conversely, faults at lower temperatures are velocity weakening and therefore prone to earthquake slip. We have investigated whether dislocation processes are important around faults in quartzites on seismic timescales, by inducing fault slip on a saw cut surface in novaculite blocks. Deformation was carried out at 450°C and 600°C in a Griggs apparatus. Slip rates of 8.3 x 10-7s-1 allowed total slip, u, of 0.5mm to be achieved in c. 10 minutes. Failure occurred at peak differential stresses of ~1.7 GPa and 1.4 GPa respectively, followed by significant weakening. Structures of the novaculite within and surrounding the fault surface were examined using EBSD, FIB-SEM and TEM to elucidate changes to their dislocation substructure. In the sample deformed at 450°C, a ~50μm thick layer of amorphous / non-crystalline silica was developed on the saw-cut surface during deformation. Rare clasts of the wall rock are preserved within this material. The surrounding sample is mostly composed of equant quartz grains of 5-10μm diameter that lack a preferred orientation, contain very few intercrystalline dislocations, and are divided by organised high angle grain boundaries. After deformation, most quartz grains within the sample retain their starting microstructure. However, within ~10μm of the sliding surface, dislocations are more common, and these are arranged into elongated, tangled zones (subgrain boundaries?). Microfractures are also observed. These microstructures are characteristic of deformation accommodated by low temperature plasticity. Our preliminary observations suggest that dislocation processes may be able to accommodate some deformation around fault

  14. Effect of oxygen on dislocation multiplication in silicon crystals

    NASA Astrophysics Data System (ADS)

    Fukushima, Wataru; Harada, Hirofumi; Miyamura, Yoshiji; Imai, Masato; Nakano, Satoshi; Kakimoto, Koichi

    2018-03-01

    This paper aims to clarify the effect of oxygen on dislocation multiplication in silicon single crystals grown by the Czochralski and floating zone methods using numerical analysis. The analysis is based on the Alexander-Haasen-Sumino model and involves oxygen diffusion from the bulk to the dislocation cores during the annealing process in a furnace. The results show that after the annealing process, the dislocation density in silicon single crystals decreases as a function of oxygen concentration. This decrease can be explained by considering the unlocking stress caused by interstitial oxygen atoms. When the oxygen concentration is 7.5 × 1017 cm-3, the total stress is about 2 MPa and the unlocking stress is less than 1 MPa. As the oxygen concentration increases, the unlocking stress also increases; however, the dislocation velocity decreases.

  15. Modeling and 2-D discrete simulation of dislocation dynamics for plastic deformation of metal

    NASA Astrophysics Data System (ADS)

    Liu, Juan; Cui, Zhenshan; Ou, Hengan; Ruan, Liqun

    2013-05-01

    Two methods are employed in this paper to investigate the dislocation evolution during plastic deformation of metal. One method is dislocation dynamic simulation of two-dimensional discrete dislocation dynamics (2D-DDD), and the other is dislocation dynamics modeling by means of nonlinear analysis. As screw dislocation is prone to disappear by cross-slip, only edge dislocation is taken into account in simulation. First, an approach of 2D-DDD is used to graphically simulate and exhibit the collective motion of a large number of discrete dislocations. In the beginning, initial grains are generated in the simulation cells according to the mechanism of grain growth and the initial dislocation is randomly distributed in grains and relaxed under the internal stress. During the simulation process, the externally imposed stress, the long range stress contribution of all dislocations and the short range stress caused by the grain boundaries are calculated. Under the action of these forces, dislocations begin to glide, climb, multiply, annihilate and react with each other. Besides, thermal activation process is included. Through the simulation, the distribution of dislocation and the stress-strain curves can be obtained. On the other hand, based on the classic dislocation theory, the variation of the dislocation density with time is described by nonlinear differential equations. Finite difference method (FDM) is used to solve the built differential equations. The dislocation evolution at a constant strain rate is taken as an example to verify the rationality of the model.

  16. Movement of basal plane dislocations in GaN during electron beam irradiation

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Yakimov, E. B.; National University of Science and Technology MISiS, Leninskiy pr. 4, Moscow 119049; Vergeles, P. S.

    The movement of basal plane segments of dislocations in low-dislocation-density GaN films grown by epitaxial lateral overgrowth as a result of irradiation with the probing beam of a scanning electron microscope was detected by means of electron beam induced current. Only a small fraction of the basal plane dislocations was susceptible to such changes and the movement was limited to relatively short distances. The effect is explained by the radiation enhanced dislocation glide for dislocations pinned by two different types of pinning sites: a low-activation-energy site and a high-activation-energy site. Only dislocation segments pinned by the former sites can bemore » moved by irradiation and only until they meet the latter pinning sites.« less

  17. A new scheme of general hybrid projective complete dislocated synchronization

    NASA Astrophysics Data System (ADS)

    Chu, Yan-dong; Chang, Ying-Xiang; An, Xin-lei; Yu, Jian-Ning; Zhang, Jian-Gang

    2011-03-01

    Based on the Lyapunov stability theorem, a new type of chaos synchronization, general hybrid projective complete dislocated synchronization (GHPCDS), is proposed under the framework of drive-response systems. The difference between the GHPCDS and complete synchronization is that every state variable of drive system does not equal the corresponding state variable, but equal other ones of response system while evolving in time. The GHPCDS includes complete dislocated synchronization, dislocated anti-synchronization and projective dislocated synchronization as its special item. As examples, the Lorenz chaotic system, Rössler chaotic system, hyperchaotic Chen system and hyperchaotic Lü system are discussed. Numerical simulations are given to show the effectiveness of these methods.

  18. The Educational Needs of Dislocated Workers in Minnesota.

    ERIC Educational Resources Information Center

    Park, Rosemarie J.; And Others

    A study was conducted to determine if dislocated workers in Minnesota felt they had sufficient reading and mathematics skills to obtain new employment or enter retraining programs. A representative group of 168 dislocated workers who had been employed in manufacturing, taconite mining, lumber, and farming were interviewed from June through…

  19. Solute atmospheres at dislocations

    DOE PAGES

    Hirth, John P.; Barnett, David M.; Hoagland, Richard G.

    2017-06-01

    In this study, a two-dimensional plane strain elastic solution is determined for the Cottrell solute atmosphere around an edge dislocation in an infinitely long cylinder of finite radius (the matrix), in which rows of solutes are represented by cylindrical rods with in-plane hydrostatic misfit (axial misfit is also considered). The periphery of the matrix is traction-free, thus introducing an image solute field which generates a solute-solute interaction energy that has not been considered previously. The relevant energy for the field of any distribution of solutes coexistent with a single edge dislocation along the (matrix) cylinder axis is determined, and coherencymore » effects are discussed and studied. Monte Carlo simulations accounting for all pertinent interactions over a range of temperatures are found to yield solute distributions different from classical results, namely, (1) Fermi-Dirac condensations at low temperatures at the free surface, (2) the majority of the atmosphere lying within an unexpectedly large non-linear interaction region near the dislocation core, and (3) temperature-dependent asymmetrical solute arrangements that promote bending. The solute distributions at intermediate temperatures show a 1/r dependence in agreement with previous linearized approximations. With a standard state of solute corresponding to a mean concentration, c 0, the relevant interaction energy expression presented in this work is valid when extended to large concentrations for which Henry's Law and Vegard's Law do not apply.« less

  20. Solute atmospheres at dislocations

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Hirth, John P.; Barnett, David M.; Hoagland, Richard G.

    In this study, a two-dimensional plane strain elastic solution is determined for the Cottrell solute atmosphere around an edge dislocation in an infinitely long cylinder of finite radius (the matrix), in which rows of solutes are represented by cylindrical rods with in-plane hydrostatic misfit (axial misfit is also considered). The periphery of the matrix is traction-free, thus introducing an image solute field which generates a solute-solute interaction energy that has not been considered previously. The relevant energy for the field of any distribution of solutes coexistent with a single edge dislocation along the (matrix) cylinder axis is determined, and coherencymore » effects are discussed and studied. Monte Carlo simulations accounting for all pertinent interactions over a range of temperatures are found to yield solute distributions different from classical results, namely, (1) Fermi-Dirac condensations at low temperatures at the free surface, (2) the majority of the atmosphere lying within an unexpectedly large non-linear interaction region near the dislocation core, and (3) temperature-dependent asymmetrical solute arrangements that promote bending. The solute distributions at intermediate temperatures show a 1/r dependence in agreement with previous linearized approximations. With a standard state of solute corresponding to a mean concentration, c 0, the relevant interaction energy expression presented in this work is valid when extended to large concentrations for which Henry's Law and Vegard's Law do not apply.« less

  1. Broken or dislocated jaw

    MedlinePlus

    ... broken or dislocated jaw requires prompt medical attention. Emergency symptoms include difficulty breathing or heavy bleeding. ... safety equipment, such as a helmet when playing football, or using ... can prevent or minimize some injuries to the face or jaw.

  2. Subtalar dislocation without associated fractures: Case report and review of literature

    PubMed Central

    Giannoulis, Dionisios; Papadopoulos, Dimitrios V; Lykissas, Marios G; Koulouvaris, Panagiotis; Gkiatas, Ioannis; Mavrodontidis, Alexandros

    2015-01-01

    Isolated subtalar dislocations are unusual injuries due to the inherent instability of the talus. Subtalar dislocations are frequently associated with fractures of the malleoli, the talus, the calcaneus or the fifth metatarsal. Four types of subtalar dislocation have been described according to the direction of the foot in relation to the talus: medial, lateral posterior and anterior. It has been shown that some of these dislocations may spontaneously reduce. A rare case of a 36-year-old male patient who sustained a closed medial subtalar dislocation without any associated fractures of the ankle is reported. The patient suffered a pure closed medial subtalar dislocation that is hardly reported in the literature. Six months after injury the patient did not report any pain, had a satisfactory range of motion, and no signs of residual instability or early posttraumatic osteoarthritis. The traumatic mechanism, the treatment options, and the importance of a stable and prompt closed reduction and early mobilization are discussed. PMID:25893182

  3. Optimized cartilage visualization using 7-T sodium ((23)Na) imaging after patella dislocation.

    PubMed

    Widhalm, Harald K; Apprich, Sebastian; Welsch, Goetz H; Zbyn, Stefan; Sadoghi, Patrick; Vekszler, György; Hamböck, Martina; Weber, Michael; Hajdu, Stefan; Trattnig, Siegfried

    2016-05-01

    Retropatellar cartilage lesions often occur in the course of recurrent patella dislocation. Aim of this study was to develop a more detailed method for examining cartilage tissue, in order to reduce patient discomfort and time of care. For detailed diagnosing, a 7-T MRI of the knee joint and patella was performed in nine patients, with mean age of 26.4 years, after patella dislocation to measure the cartilage content in three different regions of interest of the patella. Axial sodium ((23)Na) images were derived from an optimized 3D GRE sequence on a 7-T MR scanner. Morphological cartilage grading was performed, and sodium signal-to-noise ratio (SNR) values were calculated. Mean global sodium values and SNR were compared between patients and volunteers. Two out of nine patients showed a maximum cartilage defect of International Cartilage Repair Society (ICRS) grade 3, three of grade 2, three of  grade 1, and one patient showed no cartilage defect. The mean SNR in sodium images for cartilage was 13.4 ± 2.5 in patients and 14.6 ± 3.7 in volunteers (n.s.). A significant negative correlation between age and global sodium SNR for cartilage was found in the medial facet (R = -0.512; R (2) = 0.26; p = 0.030). Mixed-model ANOVA yielded a marked decrease of the sodium SNR, with increasing grade of cartilage lesions (p < 0.001). Utilization of the (23)Na MR imaging will make earlier detection of alterations to the patella cartilage after dislocation possible and will help prevent subsequent disease due to start adequate therapy earlier in the rehabilitation process. II.

  4. Right sternoclavicular dislocation after traumatic delivery: a case report.

    PubMed

    Aretz, S; Benz-Bohm, G; Helling, H J; Herkenrath, P; Roth, B

    1999-12-01

    Sternoclavicular (SC) dislocation is an injury that is very rare in the newborn. Thus far there have been no reports describing this in neonates after a traumatic birth injury. This condition can be difficult to differentiate from epiphyseal separation, which occurs more often in older children. For successful treatment, early diagnosis is essential. Timely surgical reposition and fixation with following immobilization is recommended in instances of complete (SC) dislocation. We report a trauma-induced case of SC dislocation in a neonate successfully managed by polydioxanon cord fixation.

  5. Bilateral spontaneous crystalline lens dislocation to the anterior chamber: a case report.

    PubMed

    Jovanović, Milos

    2013-01-01

    There are various reasons for the lens dislocation. Spontaneous dislocation of a clear lens is extremely rare, especially its dislocation to the anterior chamber. The author presents a case of spontaneous clear lens dislocation to the anterior chamber in both eyes in a patient without the history of any trauma. Dislocation occurred spontaneously, first in the left eye, along with a sudden decrease of vision. The ophthalmologist found a clear lens in the anterior chamber, without any sign of an elevated intraocular pressure, as should have been expected. The dislocated lens was removed surgically (intracapsular extraction) with the preventive basal iridectomy. Two years later, the same happened in the right eye: clear lens moved spontaneously to the anterior chamber, with a decrease of vision, but again without any rise of intraocular pressure and/or any pain. Intracapsular extraction of the lens with basal iridectomy was done again. The presented case demonstrates that spontaneous dislocation of the transparent lens to the eye anterior chamber can occur in both eyes at different time intervals. We suggest the removal of dislocated lens in the anterior chamber by the intracapsular extraction.

  6. A combined dislocation fan-finite element (DF-FE) method for stress field simulation of dislocations emerging at the free surfaces of 3D elastically anisotropic crystals

    NASA Astrophysics Data System (ADS)

    Balusu, K.; Huang, H.

    2017-04-01

    A combined dislocation fan-finite element (DF-FE) method is presented for efficient and accurate simulation of dislocation nodal forces in 3D elastically anisotropic crystals with dislocations intersecting the free surfaces. The finite domain problem is decomposed into half-spaces with singular traction stresses, an infinite domain, and a finite domain with non-singular traction stresses. As such, the singular and non-singular parts of the traction stresses are addressed separately; the dislocation fan (DF) method is introduced to balance the singular traction stresses in the half-spaces while the finite element method (FEM) is employed to enforce the non-singular boundary conditions. The accuracy and efficiency of the DF method is demonstrated using a simple isotropic test case, by comparing it with the analytical solution as well as the FEM solution. The DF-FE method is subsequently used for calculating the dislocation nodal forces in a finite elastically anisotropic crystal, which produces dislocation nodal forces that converge rapidly with increasing mesh resolutions. In comparison, the FEM solution fails to converge, especially for nodes closer to the surfaces.

  7. Acetabular cup position and risk of dislocation in primary total hip arthroplasty.

    PubMed

    Seagrave, Kurt G; Troelsen, Anders; Malchau, Henrik; Husted, Henrik; Gromov, Kirill

    2017-02-01

    Background and purpose - Hip dislocation is one of the most common complications following total hip arthroplasty (THA). Several factors that affect dislocation have been identified, including acetabular cup positioning. Optimal values for cup inclination and anteversion are debatable. We performed a systematic review to describe the different methods for measuring cup placement, target zones for cup positioning, and the association between cup positioning and dislocation following primary THA. Methods - A systematic search of literature in the PubMed database was performed (January and February 2016) to identify articles that compared acetabular cup positioning and the risk of dislocation. Surgical approach and methods for measurement of cup angles were also considered. Results - 28 articles were determined to be relevant to our research question. Some articles demonstrated that cup positioning influenced postoperative dislocation whereas others did not. The majority of articles could not identify a statistically significant difference between dislocating and non-dislocating THA with regard to mean angles of cup anteversion and inclination. Most of the articles that assessed cup placement within the Lewinnek safe zone did not show a statistically significant reduction in dislocation rate. Alternative target ranges have been proposed by several authors. Interpretation - The Lewinnek safe zone could not be justified. It is difficult to draw broad conclusions regarding a definitive target zone for cup positioning in THA, due to variability between studies and the likely multifactorial nature of THA dislocation. Future studies comparing cup positioning and dislocation rate should investigate surgical approach separately. Standardized tools for measurement of cup positioning should be implemented to allow comparison between studies.

  8. Effects of solutes on dislocation nucleation from grain boundaries

    DOE PAGES

    Borovikov, Valery; Mendelev, Mikhail I.; King, Alexander H.

    2016-12-27

    When grain sizes are reduced to the nanoscale, grain boundaries (GB) become the dominant sources of the dislocations that enable plastic deformation. Here, we present the first molecular dynamics (MD) study of the effect of substitutional solutes on the dislocation nucleation process from GBs during uniaxial tensile deformation. A simple bi-crystal geometry is utilized in which the nucleation and propagation of dislocations away from a GB is the only active mechanism of plastic deformation. Solutes with atomic radii both larger and smaller than the solvent atomic radius were considered. Although the segregation sites are different for the two cases, bothmore » produce increases in the stress required to nucleate a dislocation. MD simulations at room temperature revealed that this increase in the nucleation stress is associated with changes of the GB structure at the emission site caused by dislocation emission, leading to increases in the heats of segregation of the solute atoms, which cannot diffuse to lower-energy sites on the timescale of the nucleation event. These results contribute directly to understanding the strength of nanocrystalline materials, and suggest suitable directions for nanocrystalline alloy design leading toward structural applications.« less

  9. A micro S-shaped optical fiber temperature sensor based on dislocation fiber splice

    NASA Astrophysics Data System (ADS)

    Yan, Haitao; Li, Pengfei; Zhang, Haojie; Shen, Xiaoyue; Wang, Yongzhen

    2017-12-01

    We fabricated a simple, compact, and stable temperature sensor based on an S-shaped dislocated optical fiber. The dislocation optical fiber has two splice points, and we obtained the optimal parameters based on the theory and our experiment, such as the dislocation amount and length of the dislocation optical fiber. According to the relationship between the temperature and the peak wavelength shift, the temperature of the environment can be obtained. Then, we made this fiber a micro bending as S-shape between the two dislocation points, and the S-shaped micro bending part could release stress with the change in temperature and reduce the effect of stress on the temperature measurement. This structure could solve the problem of sensor distortion caused by the cross response of temperature and stress. We measured the S-shaped dislocation fiber sensor and the dislocation fiber without S-shape under the same environment and conditions, and the S-shaped dislocation fiber had the advantages of the stable reliability and good linearity.

  10. Characteristics of dislocation structure in creep deformed lamellar tial alloy within primary regime

    NASA Astrophysics Data System (ADS)

    Cho, H. S.; Nam, Soo W.

    1999-06-01

    In this investigation, dislocations of a lamellar TiAl alloy are analyzed after creeping in the primary range at 800°C/200MPa in order to interpret their mobility It was found that the dislocation density in γ-laths decreased as the creep deformation proceeds within primary creep regime Schmid factor analysis suggests that the creep deformation in the early stage of the primary creep regime is controlled by the gliding of some of the initial dislocations which have a high enough Schmid factor As the creep deformation progressed, those dislocations with high Schmid factors slip preferentially to be annihilated at the α-γ interface For further continuous deformation, dislocation generation is required, and for this, α-phase is transformed to γ-phase in order to generate new dislocations A slow dislocation generation process by phase transformation of α-phase compared with the absorbing rate to sinks is responsible for the decreasing dislocation density as the creep strain increases

  11. Dislocation pileup as a representation of strain accumulation on a strike-slip fault

    USGS Publications Warehouse

    Savage, J.C.

    2006-01-01

    The conventional model of strain accumulation on a vertical transform fault is a discrete screw dislocation in an elastic half-space with the Burgers vector of the dislocation increasing at the rate of relative plate motion. It would be more realistic to replace that discrete dislocation by a dislocation distribution, presumably a pileup in which the individual dislocations are in equilibrium. The length of the pileup depends upon the applied stress and the amount of slip that has occurred at depth. I argue here that the dislocation pileup (the transition on the fault from no slip to slip at the full plate rate) occupies a substantial portion of the lithosphere thickness. A discrete dislocation at an adjustable depth can reproduce the surface deformation profile predicted by a pileup so closely that it will be difficult to distinguish between the two models. The locking depth (dislocation depth) of that discrete dislocation approximation is substantially (???30%) larger than that (depth to top of the pileup) in the pileup model. Thus, in inverting surface deformation data using the discrete dislocation model, the locking depth in the model should not be interpreted as the true locking depth. Although dislocation pileup models should provide a good explanation of the surface deformation near the fault trace, that explanation may not be adequate at greater distances from the fault trace because approximating the expected horizontally distributed deformation at subcrustal depths by uniform slip concentrated on the fault is not justified.

  12. Structure of screw dislocation core in Ta at high pressure

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Wang, Shaofeng, E-mail: sfwang@cqu.edu.cn; Jiang, Na; Wang, Rui

    2014-03-07

    The core structure and Peierls stress of the 1/2 〈111〉(110) screw dislocation in Ta have been investigated theoretically using the modified Peierls–Nabarro theory that takes into account the discreteness effect of crystal. The lattice constants, the elastic properties, and the generalized-stacking-fault energy(γ-surface) under the different pressures have been calculated from the electron density functional theory. The core structure of dislocation is determined by the modified Peierls equation, and the Peierls stress is evaluated from the dislocation energy that varies periodically as dislocation moves. The results show the core width and Peierls stress in Ta are weakly dependent of the pressuremore » up to 100 GPa when the length and stress are measured separately by the Burgers vector b and shear modulus μ. This indicates that core structure is approximately scaling invariant for the screw dislocation in Ta. The scaled plasticity of Ta changes little in high pressure environment.« less

  13. Predicting the structure of screw dislocations in nanoporous materials

    NASA Astrophysics Data System (ADS)

    Walker, Andrew M.; Slater, Ben; Gale, Julian D.; Wright, Kate

    2004-10-01

    Extended microscale crystal defects, including dislocations and stacking faults, can radically alter the properties of technologically important materials. Determining the atomic structure and the influence of defects on properties remains a major experimental and computational challenge. Using a newly developed simulation technique, the structure of the 1/2a <100> screw dislocation in nanoporous zeolite A has been modelled. The predicted channel structure has a spiral form that resembles a nanoscale corkscrew. Our findings suggest that the dislocation will enhance the transport of molecules from the surface to the interior of the crystal while retarding transport parallel to the surface. Crucially, the dislocation creates an activated, locally chiral environment that may have enantioselective applications. These predictions highlight the influence that microscale defects have on the properties of structurally complex materials, in addition to their pivotal role in crystal growth.

  14. AC-130 Employment

    DTIC Science & Technology

    2006-01-01

    1 AC -130 Employment Subject Area Aviation EWS 2006 Author Captain Robert Hornick, USMC Report Documentation Page Form ApprovedOMB No. 0704...00-2006 4. TITLE AND SUBTITLE AC -130 Employment 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) 5d. PROJECT NUMBER... AC -130 gunship is an aircraft that can provide all of these needs. Regrettably, there are too few AC -130’s in the inventory to cover all the needs

  15. Hydrogen-vacancy-dislocation interactions in α-Fe

    NASA Astrophysics Data System (ADS)

    Tehranchi, A.; Zhang, X.; Lu, G.; Curtin, W. A.

    2017-02-01

    Atomistic simulations of the interactions between dislocations, hydrogen atoms, and vacancies are studied to assess the viability of a recently proposed mechanism for the formation of nanoscale voids in Fe-based steels in the presence of hydrogen. Quantum-mechanics/molecular-mechanics method calculations confirm molecular statics simulations based on embedded atom method (EAM) potential showing that individual vacancies on the compressive side of an edge dislocation can be transported with the dislocation as it glides. Molecular dynamics simulations based on EAM potential then show, however, that vacancy clusters in the glide plane of an approaching dislocation are annihilated or reduced in size by the creation of a double-jog/climb process that is driven by the huge reduction in energy accompanying vacancy annihilation. The effectiveness of annihilation/reduction processes is not reduced by the presence of hydrogen in the vacancy clusters because typical V-H cluster binding energies are much lower than the vacancy formation energy, except at very high hydrogen content in the cluster. Analysis of a range of configurations indicates that hydrogen plays no special role in stabilizing nanovoids against jog formation processes that shrink voids. Experimental observations of nanovoids on the fracture surfaces of steels must be due to as-yet undetermined processes.

  16. Wide field of view CT and acromioclavicular joint instability: A technical innovation.

    PubMed

    Dyer, David R; Troupis, John M; Kamali Moaveni, Afshin

    2015-06-01

    A 21-year-old female with a traumatic shoulder injury is investigated and managed for symptoms relating to this injury. Pathology at the acromioclavicular joint is detected clinically; however, clinical examination and multiple imaging modalities do not reach a unified diagnosis on the grading of this acromioclavicular joint injury. When management appropriate to that suggested injury grading fail to help the patient's symptoms, further investigation methods were utilised. Wide field of view, dynamic CT (4D CT) is conducted on the patient's affected shoulder using a 320 × 0.5 mm detector multislice CT. Scans were conducted with a static table as the patient completed three movements of the affected shoulder. Capturing multiple data sets per second over a z-axis of 16 cm, measurements of the acromioclavicular joint were made, to show dynamic changes at the joint. Acromioclavicular (AC) joint translations were witnessed in three planes (a previously unrecognised pathology in the grading of acromioclavicular joint injuries). Translation in multiple planes was also not evident on careful clinical examination of this patient. AC joint width, anterior-posterior translation, superior-inferior translation and coracoclavicular width were measured with planar reconstructions while volume-rendered images and dynamic sequences aiding visual understanding of the pathology. Wide field of view dynamic CT (4D CT) is an accurate and quick modality to diagnose complex acromioclavicular joint injury. It provides dynamic information that no other modality can; 4D CT shows future benefits for clinical approach to diagnosis and management of acromioclavicular joint injury, and other musculoskeletal pathologies. © 2015 The Royal Australian and New Zealand College of Radiologists.

  17. Effect of solute atoms on dislocation motion in Mg: An electronic structure perspective

    PubMed Central

    Tsuru, T.; Chrzan, D. C.

    2015-01-01

    Solution strengthening is a well-known approach to tailoring the mechanical properties of structural alloys. Ultimately, the properties of the dislocation/solute interaction are rooted in the electronic structure of the alloy. Accordingly, we compute the electronic structure associated with, and the energy barriers to dislocation cross-slip. The energy barriers so obtained can be used in the development of multiscale models for dislocation mediated plasticity. The computed electronic structure can be used to identify substitutional solutes likely to interact strongly with the dislocation. Using the example of a-type screw dislocations in Mg, we compute accurately the Peierls barrier to prismatic plane slip and argue that Y, Ca, Ti, and Zr should interact strongly with the studied dislocation, and thereby decrease the dislocation slip anisotropy in the alloy. PMID:25740411

  18. Ubiquity of quantum zero-point fluctuations in dislocation glide

    NASA Astrophysics Data System (ADS)

    Landeiro Dos Reis, Marie; Choudhury, Anshuman; Proville, Laurent

    2017-03-01

    Modeling the dislocation glide through atomic scale simulations in Al, Cu, and Ni and in solid solution alloys Al(Mg) and Cu(Ag), we show that in the course of the plastic deformation the variation of the crystal zero-point energy (ZPE) and the dislocation potential energy barriers are of opposite sign. The multiplicity of situations where we have observed the same trend allows us to conclude that quantum fluctuations, giving rise to the crystal ZPE, make easier the dislocation glide in most materials, even those constituted of atoms heavier than H and He.

  19. Strength of Dislocation Junctions in FCC-monocrystals with a [\\overline{1}11] Deformation Axis

    NASA Astrophysics Data System (ADS)

    Kurinnaya, R. I.; Zgolich, M. V.; Starenchenko, V. A.

    2017-07-01

    The paper examines all dislocation reactions implemented in FCC-monocrystals with axis deformation oriented in the [\\overline{1}11] direction. It identifies the fracture stresses of dislocation junctions depending on intersection geometry of the reacting dislocation loop segments. Estimates are produced for the full spectrum of reacting forest dislocations. The paper presents the statistical data of the research performed and identifies the share of long strong dislocation junctions capable of limiting the zone of dislocation shift.

  20. Lateral Movement of Screw Dislocations During Homoepitaxial Growth and Devices Yielded Therefrom Free of the Detrimental Effects of Screw Dislocations

    NASA Technical Reports Server (NTRS)

    Neudeck, Philip G. (Inventor); Powell, J. Anthony (Inventor)

    2004-01-01

    The present invention is related to a method that enables and improves wide bandgap homoepitaxial layers to be grown on axis single crystal substrates, particularly SiC. The lateral positions of the screw dislocations in epitaxial layers are predetermined instead of random, which allows devices to be reproducibly patterned to avoid performance degrading crystal defects normally created by screw dislocations.

  1. High purity, low dislocation GaAs single crystals

    NASA Technical Reports Server (NTRS)

    Chen, R. T.; Holmes, D. E.; Kirkpatrick, C. G.

    1983-01-01

    Liquid encapsulated Czochralski crystal growth techniques for producing undoped, high resistivity, low dislocation material suitable for device applications is described. Technique development resulted in reduction of dislocation densities in 3 inch GaAs crystals. Control over the melt stoichiometry was determined to be of critical importance for the reduction of twinning and polycrystallinity during growth.

  2. Microstructural comparison of the kinematics of discrete and continuum dislocations models

    NASA Astrophysics Data System (ADS)

    Sandfeld, Stefan; Po, Giacomo

    2015-12-01

    The Continuum Dislocation Dynamics (CDD) theory and the Discrete Dislocation Dynamics (DDD) method are compared based on concise mathematical formulations of the coarse graining of discrete data. A numerical tool for converting from a discrete to a continuum representation of a given dislocation configuration is developed, which allows to directly compare both simulation approaches based on continuum quantities (e.g. scalar density, geometrically necessary densities, mean curvature). Investigating the evolution of selected dislocation configurations within analytically given velocity fields for both DDD and CDD reveals that CDD contains a surprising number of important microstructural details.

  3. The Feasibility of Applying AC Driven Low-Temperature Plasma for Multi-Cycle Detonation Initiation

    NASA Astrophysics Data System (ADS)

    Zheng, Dianfeng

    2016-11-01

    Ignition is a key system in pulse detonation engines (PDE). As advanced ignition methods, nanosecond pulse discharge low-temperature plasma ignition is used in some combustion systems, and continuous alternating current (AC) driven low-temperature plasma using dielectric barrier discharge (DBD) is used for the combustion assistant. However, continuous AC driven plasmas cannot be used for ignition in pulse detonation engines. In this paper, experimental and numerical studies of pneumatic valve PDE using an AC driven low-temperature plasma igniter were described. The pneumatic valve was jointly designed with the low-temperature plasma igniter, and the numerical simulation of the cold-state flow field in the pneumatic valve showed that a complex flow in the discharge area, along with low speed, was beneficial for successful ignition. In the experiments ethylene was used as the fuel and air as oxidizing agent, ignition by an AC driven low-temperature plasma achieved multi-cycle intermittent detonation combustion on a PDE, the working frequency of the PDE reached 15 Hz and the peak pressure of the detonation wave was approximately 2.0 MPa. The experimental verifications of the feasibility in PDE ignition expanded the application field of AC driven low-temperature plasma. supported by National Natural Science Foundation of China (No. 51176001)

  4. Biomechanical Analysis of Implanted Clavicle Hook Plates With Different Implant Depths and Materials in the Acromioclavicular Joint: A Finite Element Analysis Study.

    PubMed

    Lee, Cheng-Hung; Shih, Cheng-Min; Huang, Kui-Chou; Chen, Kun-Hui; Hung, Li-Kun; Su, Kuo-Chih

    2016-11-01

    Clinical implantation of clavicle hook plates is often used as a treatment for acromioclavicular joint dislocation. However, it is not uncommon to find patients that have developed acromion osteolysis or had peri-implant fracture after hook plate fixation. With the aim of preventing complications or fixation failure caused by implantation of inappropriate clavicle hook plates, the present study investigated the biomechanics of clavicle hook plates made of different materials and with different hook depths in treating acromioclavicular joint dislocation, using finite element analysis (FEA). This study established four parts using computer models: the clavicle, acromion, clavicle hook plate, and screws, and these established models were used for FEA. Moreover, implantations of clavicle hook plates made of different materials (stainless steel and titanium alloy) and with different depths (12, 15, and 18 mm) in patients with acromioclavicular joint dislocation were simulated in the biomechanical analysis. The results indicate that deeper implantation of the clavicle hook plate reduces stress on the clavicle, and also reduces the force applied to the acromion by the clavicle hook plate. Even though a clavicle hook plate made of titanium alloy (a material with a lower Young's modulus) reduces the force applied to the acromion by the clavicle hook plate, slightly higher stress on the clavicle may occur. The results obtained in this study provide a better reference for orthopedic surgeons in choosing different clavicle hook plates for surgery. Copyright © 2016 International Center for Artificial Organs and Transplantation and Wiley Periodicals, Inc.

  5. Mid-Term Outcomes After Open Reduction Internal Fixation of Proximal Interphalangeal Joint Dorsal Fracture-Dislocations Through a Volar, Shotgun Approach and a Review of the Literature

    PubMed Central

    Giugale, Juan Marcelo; Wang, Juntian; Kaufmann, Robert A.; Fowler, John R.

    2017-01-01

    Background: Proximal interphalangeal (PIP) fracture dislocations remain a complex injury pattern to treat. There are several treatment methods available aimed to restore stability, preserve range of motion, and reconstitute the articular surface. This study looked at the mid-term clinical and radiographic results of open reduction internal fixation through a shotgun approach of comminuted PIP fracture dislocations. Methods: A retrospective review was conducted of all PIP fracture dislocations treated through a volar, shotgun approach at a single institution over a 15-year period. Patients identified were contacted and asked to return to the office for clinical and radiographic evaluation. Patient reported outcomes were assessed with the Michigan hand questionnaire (MHQ) and visual analog scale (VAS) for pain. Results: 5 patients returned to the office for further evaluation with average follow-up of 69 months (range, 33-133 months). 3 patients were found to have post traumatic arthritis on radiographs. 1 case had recurrent instability and one case had a deep infection, both necessitating further surgical intervention. Average PIP arc of motion was found to be 79°. Average VAS score of 0 and MHQ result of 95 (out of a possible score of 100) indicating no residual pain and excellent functionality of the affected hand. Conclusion: Open reduction internal fixation of comminuted PIP fracture dislocations utilizing the volar, shotgun approach provides excellent mid-term functional results despite the high incidence of post traumatic arthritis. PMID:29151999

  6. A discrete mechanics approach to dislocation dynamics in BCC crystals

    NASA Astrophysics Data System (ADS)

    Ramasubramaniam, A.; Ariza, M. P.; Ortiz, M.

    2007-03-01

    A discrete mechanics approach to modeling the dynamics of dislocations in BCC single crystals is presented. Ideas are borrowed from discrete differential calculus and algebraic topology and suitably adapted to crystal lattices. In particular, the extension of a crystal lattice to a CW complex allows for convenient manipulation of forms and fields defined over the crystal. Dislocations are treated within the theory as energy-minimizing structures that lead to locally lattice-invariant but globally incompatible eigendeformations. The discrete nature of the theory eliminates the need for regularization of the core singularity and inherently allows for dislocation reactions and complicated topological transitions. The quantization of slip to integer multiples of the Burgers' vector leads to a large integer optimization problem. A novel approach to solving this NP-hard problem based on considerations of metastability is proposed. A numerical example that applies the method to study the emanation of dislocation loops from a point source of dilatation in a large BCC crystal is presented. The structure and energetics of BCC screw dislocation cores, as obtained via the present formulation, are also considered and shown to be in good agreement with available atomistic studies. The method thus provides a realistic avenue for mesoscale simulations of dislocation based crystal plasticity with fully atomistic resolution.

  7. Column-by-column observation of dislocation motion in CdTe: Dynamic scanning transmission electron microscopy

    NASA Astrophysics Data System (ADS)

    Li, Chen; Zhang, Yu-Yang; Pennycook, Timothy J.; Wu, Yelong; Lupini, Andrew R.; Paudel, Naba; Pantelides, Sokrates T.; Yan, Yanfa; Pennycook, Stephen J.

    2016-10-01

    The dynamics of partial dislocations in CdTe have been observed at the atomic scale using aberration-corrected scanning transmission electron microscopy (STEM), allowing the mobility of different dislocations to be directly compared: Cd-core Shockley partial dislocations are more mobile than Te-core partials, and dislocation cores with unpaired columns have higher mobility than those without unpaired columns. The dynamic imaging also provides insight into the process by which the dislocations glide. Dislocations with dangling bonds on unpaired columns are found to be more mobile because the dangling bonds mediate the bond exchanges required for the dislocations to move. Furthermore, a screw dislocation has been resolved to dissociate into a Shockley partial-dislocation pair along two different directions, revealing a way for the screw dislocation to glide in the material. The results show that dynamic STEM imaging has the potential to uncover the details of dislocation motion not easily accessible by other means.

  8. The rigidity and mobility of screw dislocations in a thin film

    NASA Astrophysics Data System (ADS)

    Wang, Fei

    2018-07-01

    An equation of screw dislocations in a thin film is derived for arbitrary boundary conditions. The boundary conditions can be the free surface, the fixed surface or the gradient loading imposed on the surface. The new equation makes it possible to study changes in the dislocation structure under various gradient stress applied to the surface. The rigidity and mobility of screw dislocations in a thin film are explored by using the equation. It is found that the screw dislocation core in a thin film is like a Hookean body with a specific shear stress applied to the surface. Free-surface effects on the Peierls stress are investigated and compared with previous studies. An abnormal behavior of the Peierls stress of screw dislocations in a soft-inclusion film between two rigid films is predicted theoretically.

  9. Acromioclavicular joint dislocation: a Dog Bone button fixation alone versus Dog Bone button fixation augmented with acromioclavicular repair-a finite element analysis study.

    PubMed

    Sumanont, Sermsak; Nopamassiri, Supachoke; Boonrod, Artit; Apiwatanakul, Punyawat; Boonrod, Arunnit; Phornphutkul, Chanakarn

    2018-03-20

    Suspension suture button fixation was frequently used to treat acromioclavicular joint (ACJ) dislocation. However, there were many studies reporting about complications and residual horizontal instability after fixation. Our study compared the stability of ACJ after fixation between coracoclavicular (CC) fixation alone and CC fixation combined with ACJ repair by using finite element analysis (FEA). A finite element model was created by using CT images from the normal shoulder. The model 1 was CC fixation with suture button alone, and the model 2 was CC fixation with suture button combined with ACJ repair. Three different forces (50, 100, 200 N) applied to the model in three planes; inferior, anterior and posterior direction load to the acromion. The von Mises stress of the implants and deformation at ACJs was recorded. The ACJ repair in the model 2 could reduce the peak stress on the implant after applying the loading forces to the acromion which the ACJ repair could reduce the peak stress of the FiberWire at suture button about 90% when compared to model 1. And, the ACJ repair could reduce the deformation of the ACJ after applying the loading forces to the acromion in both vertical and horizontal planes. This FEA supports that the high-grade injuries of the ACJ should be treated with CC fixation combined with ACJ repair because this technique provides excellent stability in both vertical and horizontal planes and reduces stress to the suture button.

  10. Acetabular cup position and risk of dislocation in primary total hip arthroplasty

    PubMed Central

    Seagrave, Kurt G; Troelsen, Anders; Malchau, Henrik; Husted, Henrik; Gromov, Kirill

    2017-01-01

    Background and purpose — Hip dislocation is one of the most common complications following total hip arthroplasty (THA). Several factors that affect dislocation have been identified, including acetabular cup positioning. Optimal values for cup inclination and anteversion are debatable. We performed a systematic review to describe the different methods for measuring cup placement, target zones for cup positioning, and the association between cup positioning and dislocation following primary THA. Methods — A systematic search of literature in the PubMed database was performed (January and February 2016) to identify articles that compared acetabular cup positioning and the risk of dislocation. Surgical approach and methods for measurement of cup angles were also considered. Results— 28 articles were determined to be relevant to our research question. Some articles demonstrated that cup positioning influenced postoperative dislocation whereas others did not. The majority of articles could not identify a statistically significant difference between dislocating and non-dislocating THA with regard to mean angles of cup anteversion and inclination. Most of the articles that assessed cup placement within the Lewinnek safe zone did not show a statistically significant reduction in dislocation rate. Alternative target ranges have been proposed by several authors. Interpretation— The Lewinnek safe zone could not be justified. It is difficult to draw broad conclusions regarding a definitive target zone for cup positioning in THA, due to variability between studies and the likely multifactorial nature of THA dislocation. Future studies comparing cup positioning and dislocation rate should investigate surgical approach separately. Standardized tools for measurement of cup positioning should be implemented to allow comparison between studies. PMID:27879150

  11. Computational modelling of mesoscale dislocation patterning and plastic deformation of single crystals

    NASA Astrophysics Data System (ADS)

    Xia, Shengxu; El-Azab, Anter

    2015-07-01

    We present a continuum dislocation dynamics model that predicts the formation of dislocation cell structure in single crystals at low strains. The model features a set of kinetic equations of the curl type that govern the space and time evolution of the dislocation density in the crystal. These kinetic equations are coupled to stress equilibrium and deformation kinematics using the eigenstrain approach. A custom finite element method has been developed to solve the coupled system of equations of dislocation kinetics and crystal mechanics. The results show that, in general, dislocations self-organize in patterns under their mutual interactions. However, the famous dislocation cell structure has been found to form only when cross slip is implemented in the model. Cross slip is also found to lower the yield point, increase the hardening rate, and sustain an increase in the dislocation density over the hardening regime. Analysis of the cell structure evolution reveals that the average cell size decreases with the applied stress, which is consistent with the similitude principle.

  12. Uncovering the inertia of dislocation motion and negative mechanical response in crystals.

    PubMed

    Tang, Yizhe

    2018-01-09

    Dislocations are linear defects in crystals and their motion controls crystals' mechanical behavior. The dissipative nature of dislocation propagation is generally accepted although the specific mechanisms are still not fully understood. The inertia, which is undoubtedly the nature of motion for particles with mass, seems much less convincing for configuration propagation. We utilize atomistic simulations in conditions that minimize dissipative effects to enable uncovering of the hidden nature of dislocation motion, in three typical model metals Mg, Cu and Ta. We find that, with less/no dissipation, dislocation motion is under-damped and explicitly inertial at both low and high velocities. The inertia of dislocation motion is intrinsic, and more fundamental than the dissipative nature. The inertia originates from the kinetic energy imparted from strain energy and stored in the moving core. Peculiar negative mechanical response associated with the inertia is also discovered. These findings shed light on the fundamental nature of dislocation motion, reveal the underlying physics, and provide a new physical explanation for phenomena relevant to high-velocity dislocations.

  13. Upwardly Mobile Working-Class Adolescents: A Biographical Approach on Habitus Dislocation

    ERIC Educational Resources Information Center

    Christodoulou, Michael; Spyridakis, Manos

    2017-01-01

    Habitus dislocation is a much debatable term. By presenting life-histories of working-class adolescents, this article argues (i) that not all upwardly mobile working-class adolescents experience habitus dislocation and, (ii) that habitus dislocation has its roots in the self-initiated ruptures that face some of those who want to be upwardly mobile…

  14. Dislocation dynamics and crystal plasticity in the phase-field crystal model

    NASA Astrophysics Data System (ADS)

    Skaugen, Audun; Angheluta, Luiza; Viñals, Jorge

    2018-02-01

    A phase-field model of a crystalline material is introduced to develop the necessary theoretical framework to study plastic flow due to dislocation motion. We first obtain the elastic stress from the phase-field crystal free energy under weak distortion and show that it obeys the stress-strain relation of linear elasticity. We focus next on dislocations in a two-dimensional hexagonal lattice. They are composite topological defects in the weakly nonlinear amplitude equation expansion of the phase field, with topological charges given by the standard Burgers vector. This allows us to introduce a formal relation between the dislocation velocity and the evolution of the slowly varying amplitudes of the phase field. Standard dissipative dynamics of the phase-field crystal model is shown to determine the velocity of the dislocations. When the amplitude expansion is valid and under additional simplifications, we find that the dislocation velocity is determined by the Peach-Koehler force. As an application, we compute the defect velocity for a dislocation dipole in two setups, pure glide and pure climb, and compare it with the analytical predictions.

  15. Solute effects on edge dislocation pinning in complex alpha-Fe alloys

    NASA Astrophysics Data System (ADS)

    Pascuet, M. I.; Martínez, E.; Monnet, G.; Malerba, L.

    2017-10-01

    Reactor pressure vessel steels are well-known to harden and embrittle under neutron irradiation, mainly because of the formation of obstacles to the motion of dislocations, in particular, precipitates and clusters composed of Cu, Ni, Mn, Si and P. In this paper, we employ two complementary atomistic modelling techniques to study the heterogeneous precipitation and segregation of these elements and their effects on the edge dislocations in BCC iron. We use a special and highly computationally efficient Monte Carlo algorithm in a constrained semi-grand canonical ensemble to compute the equilibrium configurations for solute clusters around the dislocation core. Next, we use standard molecular dynamics to predict and analyze the effect of this segregation on the dislocation mobility. Consistently with expectations our results confirm that the required stress for dislocation unpinning from the precipitates formed on top of it is quite large. The identification of the precipitate resistance allows a quantitative treatment of atomistic results, enabling scale transition towards larger scale simulations, such as dislocation dynamics or phase field.

  16. Dislocation dynamics simulations of plasticity at small scales

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Zhou, Caizhi

    2010-01-01

    As metallic structures and devices are being created on a dimension comparable to the length scales of the underlying dislocation microstructures, the mechanical properties of them change drastically. Since such small structures are increasingly common in modern technologies, there is an emergent need to understand the critical roles of elasticity, plasticity, and fracture in small structures. Dislocation dynamics (DD) simulations, in which the dislocations are the simulated entities, offer a way to extend length scales beyond those of atomistic simulations and the results from DD simulations can be directly compared with the micromechanical tests. The primary objective of this researchmore » is to use 3-D DD simulations to study the plastic deformation of nano- and micro-scale materials and understand the correlation between dislocation motion, interactions and the mechanical response. Specifically, to identify what critical events (i.e., dislocation multiplication, cross-slip, storage, nucleation, junction and dipole formation, pinning etc.) determine the deformation response and how these change from bulk behavior as the system decreases in size and correlate and improve our current knowledge of bulk plasticity with the knowledge gained from the direct observations of small-scale plasticity. Our simulation results on single crystal micropillars and polycrystalline thin films can march the experiment results well and capture the essential features in small-scale plasticity. Furthermore, several simple and accurate models have been developed following our simulation results and can reasonably predict the plastic behavior of small scale materials.« less

  17. Superclimbing dislocation with a Coulomb-type interaction between jogs

    NASA Astrophysics Data System (ADS)

    Liu, Longxiang; Kuklov, Anatoly B.

    2018-03-01

    The main candidate for the superfluid pathways in solid 4He are dislocations with Burgers vector along the hcp symmetry axis. Here we focus on the quantum behavior of a generic edge dislocation which can perform superclimb; that is, it can climb due to the superflow along its core. The role of the long-range elastic interactions between jogs is addressed by Monte Carlo simulations. It is found that such interactions do not change qualitatively the phase diagram found without accounting for the long-range forces. Their main effect consists of renormalizing the effective scale determining the compressibility of the dislocation in the Tomonaga-Luttinger liquid phase. It is also found that the quantum rough phase of the dislocation can be well described within the Gaussian approximation which features off-diagonal long-range order (ODLRO) in one dimension for the superfluid order parameter along the core.

  18. Management of dislocated intraocular lenses with iris suture.

    PubMed

    Faria, Mun Y; Ferreira, Nuno P; Canastro, Mario

    2017-01-19

    Subluxated or malpositioned intraocular lenses (IOLs) and inadequate capsular support is a challenge for every ophthalmic surgeon. Iris suture of an IOL seems to be an easy technique for the management of dislocated 3-piece IOL, allowing the IOL to be placed behind the iris, far from the trabecular meshwork and corneal endothelium. The purpose of this study is to assess the results of pars plana vitrectomy (PPV) and iris suture of dislocated 3-piece acrylic IOLs. In this retrospective, nonrandomized, interventional case consecutive study, of a total of 103 dislocated IOLs, 36 eyes were considered for analysis. All 36 eyes had subluxated or totally luxated 3-piece IOL and underwent iris suture at the Ophthalmology Department of Santa Maria Hospital-North Lisbon Hospital Center, Portugal, from January 2011 until November 2015. All patients underwent 3-port 23-G PPV. The optic zone of the dislocated IOL was placed anterior to the iris with the haptics behind, in the posterior chamber. Haptics were sutured to iris followed by placement of the optics behind iris plane. Postoperative measures included best-corrected visual acuity (BCVA), IOL position, intraocular pressure, pigment dispersion, clinical signs of endothelial cell loss, and development of macular edema. A total of 36 eyes of 36 patients were included. All underwent successful iris fixation of dislocated 3-piece IOL. Mean overall follow-up was 15.9 months (range 3-58 months). At presentation, 16 eyes (44.4%) had a luxated IOL and 20 eyes (55.6%) a subluxated IOL. As underlying cause, 17 eyes (47.2%) had a history of complicated cataract surgery, 5 eyes (13.9%) had a traumatic dislocation of the IOL, and 6 eyes (16.7%) had a previous vitreoretinal surgery. A total of 8 eyes (22.2%) had late spontaneous IOL dislocation after uneventful cataract surgery. The mean preoperative BCVA was 1.09 ± 0.70 logarithm of the minimal angle of resolution (logMAR) units and mean postoperative BCVA was 0.48 ± 0.58 of log

  19. Appearance of wavefront dislocations under interference among beams with simple wavefronts

    NASA Astrophysics Data System (ADS)

    Angelsky, Oleg V.; Besaha, R. N.; Mokhun, Igor I.

    1997-12-01

    The appearance of wave front dislocations under interference among beams with simple wave fronts is considered. It is shown, that even two beams with the smooth wave fonts is possible the formation of dislocations screw type. The screw dislocations are formed in cross point of lines of equal amplitude of beams and minimum of an interference pattern.

  20. Complex and noncentrosymmetric stacking of layered metal dichalcogenide materials created by screw dislocations

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Shearer, Melinda J.; Samad, Leith; Zhang, Yi

    The interesting and tunable properties of layered metal dichalcogenides heavily depend on their phase and layer stacking. Here, we show and explain how the layer stacking and physical properties of WSe 2 are influenced by screw dislocations. A one-to-one correlation of atomic force microscopy and high- and low-frequency Raman spectroscopy of many dislocated WSe 2 nanoplates reveals variations in the number and shapes of dislocation spirals and different layer stackings that are determined by the number, rotation, and location of the dislocations. Plates with triangular dislocation spirals form noncentrosymmetric stacking that gives rise to strong second-harmonic generation and enhanced photoluminescence,more » plates with hexagonal dislocation spirals form the bulk 2H layer stacking commonly observed, and plates containing mixed dislocation shapes have intermediate noncentrosymmetric stackings with mixed properties. Multiple dislocation cores and other complexities can lead to more complex stackings and properties. Finally, these previously unobserved properties and layer stackings in WSe 2 will be interesting for spintronics and valleytronics.« less

  1. Complex and noncentrosymmetric stacking of layered metal dichalcogenide materials created by screw dislocations

    DOE PAGES

    Shearer, Melinda J.; Samad, Leith; Zhang, Yi; ...

    2017-02-08

    The interesting and tunable properties of layered metal dichalcogenides heavily depend on their phase and layer stacking. Here, we show and explain how the layer stacking and physical properties of WSe 2 are influenced by screw dislocations. A one-to-one correlation of atomic force microscopy and high- and low-frequency Raman spectroscopy of many dislocated WSe 2 nanoplates reveals variations in the number and shapes of dislocation spirals and different layer stackings that are determined by the number, rotation, and location of the dislocations. Plates with triangular dislocation spirals form noncentrosymmetric stacking that gives rise to strong second-harmonic generation and enhanced photoluminescence,more » plates with hexagonal dislocation spirals form the bulk 2H layer stacking commonly observed, and plates containing mixed dislocation shapes have intermediate noncentrosymmetric stackings with mixed properties. Multiple dislocation cores and other complexities can lead to more complex stackings and properties. Finally, these previously unobserved properties and layer stackings in WSe 2 will be interesting for spintronics and valleytronics.« less

  2. Penile Dislocation with Inversion: A Rare Complication of Blunt Pelvic Injury

    PubMed Central

    Sahadev, Ravindra; Jadhav, Vinay; Munianjanappa, Narendra Babu; Shankar, Gowri

    2018-01-01

    Penile injuries in children are usually uncommon and are predominantly associated with pelvic trauma or as postcircumcision injuries. The authors present a rare case of penile dislocation with penile inversion in a 5-year-old child occurring due to blunt pelvic injury. The child presented 3 months after pelvic injury with a suprapubic catheter for urinary diversion and absent penis with only penile skin visible. The presence of dislocated penile body was detected on magnetic resonance imaging, which was subsequently confirmed intraoperatively. During the surgery, the dislocated penis was identified and mobilized into its normal anatomical position within the remnant penile skin. Very few cases of penile dislocation have been reported in the literature. Pubic fracture with pulling of suspensory ligament resulting in dislocation of the penis would have been the probable mechanism of injury. PMID:29681700

  3. Hip arthroscopy versus open surgical dislocation for femoroacetabular impingement

    PubMed Central

    Zhang, Dagang; Chen, Long; Wang, Guanglin

    2016-01-01

    Abstract Background: This meta-analysis aims to evaluate the efficacy and safety of hip arthroscopy versus open surgical dislocation for treating femoroacetabular impingement (FAI) through published clinical trials. Methods: We conducted a comprehensive literature search using PUBMED, EMBASE, and the Cochrane Central Register of Controlled Trials databases for relevant studies on hip arthroscopy and open surgical dislocation as treatment options for FAI. Results: Compared with open surgical dislocation, hip arthroscopy resulted in significantly higher Nonarthritic Hip Scores (NAHS) at 3- and 12-month follow-ups, a significant improvement in NAHS from preoperation to 3 months postoperation, and a significantly lower reoperation rate. Open surgical dislocation resulted in a significantly improved alpha angle by the Dunn view in patients with cam osteoplasty from preoperation to postoperation, compared with hip arthroscopy. This meta-analysis demonstrated no significant differences in the modified Harris Hip Score, Hip Outcome Score-Activities of Daily Living, or Hip Outcome Score-Sport Specific Subscale at 12 months of follow-up, or in complications (including nerve damage, wound infection, and wound dehiscence). Conclusion: Hip arthroscopy resulted in higher NAHS and lower reoperation rates, but had less improvement in alpha angle in patients with cam osteoplasty, than open surgical dislocation. PMID:27741133

  4. Atlanto-occipital dislocation--part 2: The clinical use of (occipital) condyle-C1 interval, comparison with other diagnostic methods, and the manifestation, management, and outcome of atlanto-occipital dislocation in children.

    PubMed

    Pang, Dachling; Nemzek, William R; Zovickian, John

    2007-11-01

    The diagnosis of atlanto-occipital dislocation (AOD) remains problematic as a result of a lack of reliable radiodiagnostic criteria. In Part 1 of the AOD series, we showed that the normal occiput-C1 joint in children has an extremely narrow joint gap (condyle-C1 interval [CCI]) with great left-right symmetry. In Part 2, we used a CCI of 4 mm or greater measured on reformatted computed tomographic (CT) scans as the indicator for AOD and tested the diagnostic sensitivity and specificity of CCI against published criteria. The clinical manifestation, neuroimaging findings, management, and outcome of our series of patients with AOD are also reported. For diagnostic sensitivity, we applied the CCI criterion on 16 patients who fulfilled one or more accepted radiodiagnostic criteria of AOD and who showed clinical and imaging hallmarks of the syndrome. All 16 patients had plain cervical spine x-rays, head CT scans, axial cervical spine CT scans with reconstruction, and magnetic resonance imaging scans. The diagnostic yield and false-negative rate of CCI were compared with those of four published "standard" tests, namely Wholey's dens-basion interval, Powers' ratio, Harris' basion-axis interval, and Sun's interspinous ratio. The diagnostic value of "nonstandard" indicators such as cervicomedullary deficits, tectorial membrane and other ligamentous damage, perimedullary subarachnoid hemorrhage, and extra-axial blood at C1-C2 were also assessed. For diagnostic specificity, we applied CCI and the "standard" and "nonstandard" tests on 10 patients from five classes of non-AOD upper cervical injuries. The false-positive diagnostic rates for AOD of all respective tests were documented. The CCI criterion was positive in all 16 patients with AOD with a diagnostic sensitivity of 100%. Fourteen patients had bilateral AOD with disruption and widening of both OC1 joints. Two patients had unilateral AOD with only one joint wider than 4 mm. The abnormal CCI varied from 5 to 34 mm. Eight

  5. High purity low dislocation GaAs single crystals

    NASA Technical Reports Server (NTRS)

    Chen, R. T.; Holmes, D. E.; Kirkpatrick, C. G.

    1982-01-01

    Recent advances in GaAs bulk crystal growth using the LEC (liquid encapsulated Czochralski) technique are described. The dependence of the background impurity concentration and the dislocation density distribution on the materials synthesis and growth conditions were investigated. Background impurity concentrations as low as 4 x 10 to the 15th power were observed in undoped LEC GaAs. The dislocation density in selected regions of individual ingots was very low, below the 3000 cm .3000/sq cm threshold. The average dislocation density over a large annular ring on the wafers fell below the 10000/sq cm level for 3 inch diameter ingots. The diameter control during the program advanced to a diameter variation along a 3 inch ingot less than 2 mm.

  6. Advances in Discrete Dislocation Dynamics Modeling of Size-Affected Plasticity

    NASA Astrophysics Data System (ADS)

    El-Awady, Jaafar A.; Fan, Haidong; Hussein, Ahmed M.

    In dislocation-mediated plasticity of crystalline materials, discrete dislocation dynamics (DDD) methods have been widely used to predict the plastic deformation in a number of technologically important problems. These simulations have led to significant improvement in the understanding of the different mechanism that controls the mechanical properties of crystalline materials, which can greatly accelerate the future development of materials with superior properties. This chapter provides an overview of different practical applications of both two-dimensional and three-dimensional DDD simulations in the field of size-affected dislocation-mediated plasticity. The chapter is divided into two major tracks. First, DDD simulations focusing on aspects of modeling size-dependent plasticity in single crystals in uniaxial micro-compression/tension, microtorsion, microbending, and nanoindentation are discussed. Special attention is directed towards the role of cross-slip and dislocation nucleation on the overall response. Second, DDD simulations focusing on the role of interfaces, including grain and twin boundaries, on dislocation-mediated plasticity are discussed. Finally, a number of challenges that are withholding DDD simulations from reaching their full potential are discussed.

  7. [Development of polyaxial locking plate screw system of sacroiliac joint].

    PubMed

    Fan, Weijie; Xie, Xuesong; Zhou, Shuping; Zhang, Yonghu

    2014-09-01

    To develop an instrument for sacroiliac joint fixation with less injury and less complications. Firstly, 18 adult pelvic specimens (8 males and 10 females) were used to measure the anatomical data related to the locking plates and locking screws on the sacrum and ilium, and the polyaxial locking plate screw system of the sacroiliac joint was designed according to the anatomic data. This system was made of medical titanium alloy. Then 4 adult male plevic specimens were harvested and the experiment was divided into 3 groups: group A (normal pelvic), group B (the dislocated sacroiliac joint fixed with sacroiliac screws), and group C (the dislocated sacroiliac joint fixed with polyaxial locking plate screw system). The vertical displacement of sacroiliac joint under the condition of 0-700 N vertical load and the horizontal displacement on angle under the condition of 0-12 N·m torsional load were compared among the 3 groups by using the biological material test system. Finally, the simulated application test was performed on 1 adult male cadaveric specimen to observe soft tissue injury and the position of the locking plate and screw by X-ray films. According to the anatomic data of the sacrum and ilium, the polyaxial locking plate screw system of the sacroiliac joint was designed. The biomechanical results showed that the vertical displacement of the sacroiliac joint under the condition of 0-700 N vertical load in group A was significantly bigger than that in group B and group C (P < 0.05), but there was no significant difference between group B and group C (P > 0.05). The horizontal displacement on angle under the condition of 0-12 N·m torsional load in group A was significantly less than that in group B and group C (P < 0.05). The horizontal displacement on angle under the condition of 0-6 N·m torsional load in group B was bigger than that in group C, and the horizontal displacement on angle under the condition of 6-12 N·m torsional load in group B was less than

  8. PREFERED SURGICAL TECHNIQUE USED BY ORTHOPEDISTS IN ACUTE ACROMIOCLAVICULAR DISLOCATION

    PubMed Central

    NISHIMI, ALEXANDRE YUKIO; ARBEX, DEMETRIO SIMÃO; MARTINS, DIOGO LUCAS CAMPOS; GUSMÃO, CARLOS VINICIUS BUARQUE DE; BONGIOVANNI, ROBERTO RANGEL; PASCARELLI, LUCIANO

    2016-01-01

    ABSTRACT Objective: To determine whether training on shoulder and elbow surgery influences the orthopedist surgeons' preferred technique to address acute acromioclavicular joint dislocation (ACD). Methods: A survey was conducted with shoulder and elbow specialists and general orthopedists on their preferred technique to address acute ACD. Results: Thirty specialists and forty-five general orthopedists joined the study. Most specialists preferred the endobutton technique, while most general orthopedists preferred the modified Phemister procedure for coracoclavicular ligament repair using anchors. We found no difference between specialists and general orthopedists in the number of tunnels used to repair the coracoclavicular ligament; preferred method for wire insertion through the clavicular tunnels; buried versus unburied Kirschner wire insertion for acromioclavicular temporary fixation; and time for its removal; and regarding the suture thread used for deltotrapezoidal fascia closure. Conclusion: Training on shoulder and elbow surgery influences the surgeons' preferred technique to address acute ACD. Level of Evidence V, Expert Opinion. PMID:28149190

  9. Split and sealing of dislocated pipes at the front of a growing crystal

    NASA Astrophysics Data System (ADS)

    Gutkin, M. Yu.; Sheinerman, A. G.

    2004-07-01

    A model is suggested for the split of dislocated pipes at the front a growing crystal. Within the model, the pipe split occurs through the generation of a dislocation semi-loop at the pipe and crystal surfaces and its subsequent expansion into the crystal interior. The strain energy of such a dislocation semi-loop as well as the stress field of a dislocated pipe perpendicular to a flat crystal surface are calculated. The parameter regions are determined at which the expansion of the dislocation semi-loop is energetically favorable and, thus, the pipe split becomes irreversible. A mechanism is proposed for the formation of a stable semi-loop resulting in the split and possible subsequent overgrowth of the dislocated pipe.

  10. Size effects under homogeneous deformation of single crystals: A discrete dislocation analysis

    NASA Astrophysics Data System (ADS)

    Guruprasad, P. J.; Benzerga, A. A.

    Mechanism-based discrete dislocation plasticity is used to investigate the effect of size on micron scale crystal plasticity under conditions of macroscopically homogeneous deformation. Long-range interactions among dislocations are naturally incorporated through elasticity. Constitutive rules are used which account for key short-range dislocation interactions. These include junction formation and dynamic source and obstacle creation. Two-dimensional calculations are carried out which can handle high dislocation densities and large strains up to 0.1. The focus is laid on the effect of dimensional constraints on plastic flow and hardening processes. Specimen dimensions ranging from hundreds of nanometers to tens of microns are considered. Our findings show a strong size-dependence of flow strength and work-hardening rate at the micron scale. Taylor-like hardening is shown to be insufficient as a rationale for the flow stress scaling with specimen dimensions. The predicted size effect is associated with the emergence, at sufficient resolution, of a signed dislocation density. Heuristic correlations between macroscopic flow stress and macroscopic measures of dislocation density are sought. Most accurate among those is a correlation based on two state variables: the total dislocation density and an effective, scale-dependent measure of signed density.

  11. Plastic deformation of tubular crystals by dislocation glide.

    PubMed

    Beller, Daniel A; Nelson, David R

    2016-09-01

    Tubular crystals, two-dimensional lattices wrapped into cylindrical topologies, arise in many contexts, including botany and biofilaments, and in physical systems such as carbon nanotubes. The geometrical principles of botanical phyllotaxis, describing the spiral packings on cylinders commonly found in nature, have found application in all these systems. Several recent studies have examined defects in tubular crystals associated with crystalline packings that must accommodate a fixed tube radius. Here we study the mechanics of tubular crystals with variable tube radius, with dislocations interposed between regions of different phyllotactic packings. Unbinding and separation of dislocation pairs with equal and opposite Burgers vectors allow the growth of one phyllotactic domain at the expense of another. In particular, glide separation of dislocations offers a low-energy mode for plastic deformations of solid tubes in response to external stresses, reconfiguring the lattice step by step. Through theory and simulation, we examine how the tube's radius and helicity affects, and is in turn altered by, the mechanics of dislocation glide. We also discuss how a sufficiently strong bending rigidity can alter or arrest the deformations of tubes with small radii.

  12. Plastic deformation of tubular crystals by dislocation glide

    NASA Astrophysics Data System (ADS)

    Beller, Daniel A.; Nelson, David R.

    2016-09-01

    Tubular crystals, two-dimensional lattices wrapped into cylindrical topologies, arise in many contexts, including botany and biofilaments, and in physical systems such as carbon nanotubes. The geometrical principles of botanical phyllotaxis, describing the spiral packings on cylinders commonly found in nature, have found application in all these systems. Several recent studies have examined defects in tubular crystals associated with crystalline packings that must accommodate a fixed tube radius. Here we study the mechanics of tubular crystals with variable tube radius, with dislocations interposed between regions of different phyllotactic packings. Unbinding and separation of dislocation pairs with equal and opposite Burgers vectors allow the growth of one phyllotactic domain at the expense of another. In particular, glide separation of dislocations offers a low-energy mode for plastic deformations of solid tubes in response to external stresses, reconfiguring the lattice step by step. Through theory and simulation, we examine how the tube's radius and helicity affects, and is in turn altered by, the mechanics of dislocation glide. We also discuss how a sufficiently strong bending rigidity can alter or arrest the deformations of tubes with small radii.

  13. Sessile dislocations by reactions in NiAl severely deformed at room temperature

    DOE PAGES

    Geist, D.; Gammer, C.; Rentenberger, C.; ...

    2015-02-05

    B2 ordered NiAl is known for its poor room temperature (RT) ductility; failure occurs in a brittle like manner even in ductile single crystals deforming by single slip. In the present study NiAl was severely deformed at RT using the method of high pressure torsion (HPT) enabling the hitherto impossible investigation of multiple slip deformation. Methods of transmission electron microscopy were used to analyze the dislocations formed by the plastic deformation showing that as expected dislocations with Burgers vector a(100) carry the plasticity during HPT deformation at RT. In addition, we observe that they often form a(110) dislocations by dislocationmore » reactions; the a(110) dislocations are considered to be sessile based on calculations found in the literature. It is therefore concluded that the frequently encountered 3D dislocation networks containing sessile a(110) dislocations are pinned and lead to deformation-induced embrittlement. In spite of the severe deformation, the chemical order remains unchanged.« less

  14. Severe valgus deformity of the knee with permanent patellar dislocation associated with melorheostosis: a case report and review of the literature.

    PubMed

    Kitta, Yuki; Niki, Yasuo; Udagawa, Kazuhiko; Enomoto, Hiroyuki; Toyama, Yoshiaki; Suda, Yasunori

    2014-03-01

    We present a case of an 8-year-old boy diagnosed with melorheostosis who was suffering from severe genu valgum, permanent dislocation of the patella, knee flexion contracture and leg length shortening. Soft tissue contracture of the limb and subsequent joint deformities were reported to represent clinical manifestations of pediatric melorheostosis. As the epiphyseal plate had not closed, patellar reduction was achieved by soft tissue surgical stabilization, including lateral retinacular release, medial retinaculum plication, and transfer of the lateral half of the patellar tendon. At 4 years postoperatively, as a result of improved limb alignment and knee flexion contracture, the leg length shortening has improved, and the patient does not limp and participates in sports activities. Surgical intervention should be performed as early as possible, because genu valgum and external rotation of the tibia may deteriorate with age, rendering the patellar dislocation irreversible in patients with melorheostosis before epiphyseal closure. Copyright © 2012 Elsevier B.V. All rights reserved.

  15. Size dependence of yield strength simulated by a dislocation-density function dynamics approach

    NASA Astrophysics Data System (ADS)

    Leung, P. S. S.; Leung, H. S.; Cheng, B.; Ngan, A. H. W.

    2015-04-01

    The size dependence of the strength of nano- and micron-sized crystals is studied using a new simulation approach in which the dynamics of the density functions of dislocations are modeled. Since any quantity of dislocations can be represented by a density, this approach can handle large systems containing large quantities of dislocations, which may handicap discrete dislocation dynamics schemes due to the excessive computation time involved. For this reason, pillar sizes spanning a large range, from the sub-micron to micron regimes, can be simulated. The simulation results reveal the power-law relationship between strength and specimen size up to a certain size, beyond which the strength varies much more slowly with size. For specimens smaller than ∼4000b, their strength is found to be controlled by the dislocation depletion condition, in which the total dislocation density remains almost constant throughout the loading process. In specimens larger than ∼4000b, the initial dislocation distribution is of critical importance since the presence of dislocation entanglements is found to obstruct deformation in the neighboring regions within a distance of ∼2000b. This length scale suggests that the effects of dense dislocation clusters are greater in intermediate-sized specimens (e.g. 4000b and 8000b) than in larger specimens (e.g. 16 000b), according to the weakest-link concept.

  16. Edge dislocations as sinks for sub-nanometric radiation induced defects in α-iron

    NASA Astrophysics Data System (ADS)

    Anento, N.; Malerba, L.; Serra, A.

    2018-01-01

    The role of edge dislocations as sinks for small radiation induced defects in bcc-Fe is investigated by means of atomistic computer simulation. In this work we investigate by Molecular Statics (T = 0K) the interaction between an immobile dislocation line and defect clusters of small sizes invisible experimentally. The study highlights in particular the anisotropy of the interaction and distinguishes between absorbed and trapped defects. When the considered defect intersects the dislocation glide plane and the distance from the dislocation line to the defect is on the range between 2 nm and 4 nm, either total or partial absorption of the cluster takes place leading to the formation of jogs. Residual defects produced during partial absorption pin the dislocation. By the calculation of stress-strain curves we have assessed the strength of those residues as obstacles for the motion of the dislocation, which is reflected on the unpinning stresses and the binding energies obtained. When the defect is outside this range, but on planes close to the dislocation glide plane, instead of absorption we have observed a capture process. Finally, with a view to introducing explicitly in kinetic Monte Carlo models a sink with the shape of a dislocation line, we have summarized our findings on a table presenting the most relevant parameters, which define the interaction of the dislocation with the defects considered.

  17. Complete dislocation of the ulnar nerve at the elbow: a protective effect against neuropathy?

    PubMed

    Leis, A Arturo; Smith, Benn E; Kosiorek, Heidi E; Omejec, Gregor; Podnar, Simon

    2017-08-01

    Recurrent complete ulnar nerve dislocation has been perceived as a risk factor for development of ulnar neuropathy at the elbow (UNE). However, the role of dislocation in the pathogenesis of UNE remains uncertain. We studied 133 patients with complete ulnar nerve dislocation to determine whether this condition is a risk factor for UNE. In all, the nerve was palpated as it rolled over the medial epicondyle during elbow flexion. Of 56 elbows with unilateral dislocation, UNE localized contralaterally in 17 elbows (30.4%) and ipsilaterally in 10 elbows (17.9%). Of 154 elbows with bilateral dislocation, 26 had UNE (16.9%). Complete dislocation decreased the odds of having UNE by 44% (odds ratio = 0.475; P =  0.028), and was associated with less severe UNE (P = 0.045). UNE occurs less frequently and is less severe on the side of complete dislocation. Complete dislocation may have a protective effect on the ulnar nerve. Muscle Nerve 56: 242-246, 2017. © 2016 Wiley Periodicals, Inc.

  18. The key role of dislocation dissociation in the plastic behaviour of single crystal nickel-based superalloy with low stacking fault energy: Three-dimensional discrete dislocation dynamics modelling

    NASA Astrophysics Data System (ADS)

    Huang, Minsheng; Li, Zhenhuan

    2013-12-01

    To model the deformation of single crystal nickel based superalloys (SCNBS) with low stacking fault energy (SFE), three-dimensional discrete dislocation dynamics (3D-DDD) is extended by incorporating dislocation dissociation mechanism. The present 3D-DDD simulations show that, consistent with the existing TEM observation, the leading partial can enter the matrix channel efficiently while the trailing partial can hardly glide into it when the dislocation dissociation is taken into account. To determine whether the dislocation dissociation can occur or not, a critical percolation stress (CPS) based criterion is suggested. According to this CPS criterion, for SCNBS there exists a critical matrix channel width. When the channel width is lower than this critical value, the dislocation tends to dissociate into an extended configuration and vice versa. To clarify the influence of dislocation dissociation on CPS, the classical Orowan formula is improved by incorporating the SFE. Moreover, the present 3D-DDD simulations also show that the yielding stress of SCNBSs with low SFE may be overestimated up to 30% if the dislocation dissociation is ignored. With dislocation dissociation being considered, the size effect due to the width of γ matrix channel and the length of γ‧ precipitates on the stress-strain responses of SCNBS can be enhanced remarkably. In addition, due to the strong constraint effect by the two-phase microstructure in SCNBS, the configuration of formed junctions is quite different from that in single phase crystals such as Cu. The present results not only provide clear understanding of the two-phase microstructure levelled microplastic mechanisms in SCNBSs with low SFE, but also help to develop new continuum-levelled constitutive laws for SCNBSs.

  19. Theory of electron–phonon–dislon interacting system—toward a quantized theory of dislocations

    DOE PAGES

    Li, Mingda; Tsurimaki, Yoichiro; Meng, Qingping; ...

    2018-02-05

    In this paper, we provide a comprehensive theoretical framework to study how crystal dislocations influence the functional properties of materials, based on the idea of a quantized dislocation, namely a 'dislon'. In contrast to previous work on dislons which focused on exotic phenomenology, here we focus on their theoretical structure and computational power. We first provide a pedagogical introduction that explains the necessity and benefits of taking the dislon approach and why the dislon Hamiltonian takes its current form. Then, we study the electron–dislocation and phonon–dislocation scattering problems using the dislon formalism. Both the effective electron and phonon theories aremore » derived, from which the role of dislocations on electronic and phononic transport properties is computed. Compared with traditional dislocation scattering studies, which are intrinsically single-particle, low-order perturbation and classical quenched defect in nature, the dislon theory not only allows easy incorporation of quantum many-body effects such as electron correlation, electron–phonon interaction, and higher-order scattering events, but also allows proper consideration of the dislocation's long-range strain field and dynamic aspects on equal footing for arbitrary types of straight-line dislocations. This means that instead of developing individual models for specific dislocation scattering problems, the dislon theory allows for the calculation of electronic structure and electrical transport, thermal transport, optical and superconducting properties, etc, under one unified theory. Furthermore, the dislon theory has another advantage over empirical models in that it requires no fitting parameters. The dislon theory could serve as a major computational tool to understand the role of dislocations on multiple materials' functional properties at an unprecedented level of clarity, and may have wide applications in dislocated energy materials.« less

  20. Theory of electron–phonon–dislon interacting system—toward a quantized theory of dislocations

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Li, Mingda; Tsurimaki, Yoichiro; Meng, Qingping

    In this paper, we provide a comprehensive theoretical framework to study how crystal dislocations influence the functional properties of materials, based on the idea of a quantized dislocation, namely a 'dislon'. In contrast to previous work on dislons which focused on exotic phenomenology, here we focus on their theoretical structure and computational power. We first provide a pedagogical introduction that explains the necessity and benefits of taking the dislon approach and why the dislon Hamiltonian takes its current form. Then, we study the electron–dislocation and phonon–dislocation scattering problems using the dislon formalism. Both the effective electron and phonon theories aremore » derived, from which the role of dislocations on electronic and phononic transport properties is computed. Compared with traditional dislocation scattering studies, which are intrinsically single-particle, low-order perturbation and classical quenched defect in nature, the dislon theory not only allows easy incorporation of quantum many-body effects such as electron correlation, electron–phonon interaction, and higher-order scattering events, but also allows proper consideration of the dislocation's long-range strain field and dynamic aspects on equal footing for arbitrary types of straight-line dislocations. This means that instead of developing individual models for specific dislocation scattering problems, the dislon theory allows for the calculation of electronic structure and electrical transport, thermal transport, optical and superconducting properties, etc, under one unified theory. Furthermore, the dislon theory has another advantage over empirical models in that it requires no fitting parameters. The dislon theory could serve as a major computational tool to understand the role of dislocations on multiple materials' functional properties at an unprecedented level of clarity, and may have wide applications in dislocated energy materials.« less

  1. Neurological complications of the reduction of cervical spine dislocations.

    PubMed

    Mahale, Y J; Silver, J R; Henderson, N J

    1993-05-01

    We have studied the case records of 16 patients with dislocations of the cervical spine who deteriorated neurologically during or after reduction. The dislocations were reduced by skull traction in four patients, by manipulation in four and by operation in seven. This complication was not related to age, sex, mechanism of injury, or the level and the type of dislocation. Fourteen patients made substantial recoveries, one made a partial recovery and one patient remained totally paralysed and died three months later. The causes and prevention of spinal-cord damage at this stage of management are discussed, and the early use of MRI or CT myelography is recommended.

  2. Surgical treatment of acromioclavicular dislocation using the endobutton.

    PubMed

    Teodoro, Renato Loureiro; Nishimi, Alexandre Yukio; Pascarelli, Luciano; Bongiovanni, Roberto Rangel; Velasco, Marcelo Andreotti Perez; Dobashi, Eiffel Tsuyoshi

    2017-01-01

    To evaluate the clinical and radiographic results of 23 patients diagnosed with acute type III acromioclavicular dislocation treated with the Endobutton. Twenty-three patients with a diagnosis of type III acromioclavicular dislocation were treated surgically. Twenty-one patients were male (91.3%) and 2 (8.7%) were female. The dominant side was affected in 15 patients (65.21%) and the non-dominant side in 8 patients (34.79%). All patients were operated on by the same surgical team within 4 weeks of the trauma. According to the UCLA score, 14 patients (60.86%) presented excellent results, 7 patients (30.43%) had good results and 2 patients (8.69%) had regular results. The technique was effective in treating acute type III dislocations with a high degree of patient satisfaction. Level of Evidence IV, Case Series.

  3. 20 CFR 663.105 - When must adults and dislocated workers be registered?

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 20 Employees' Benefits 4 2012-04-01 2012-04-01 false When must adults and dislocated workers be... LABOR (CONTINUED) ADULT AND DISLOCATED WORKER ACTIVITIES UNDER TITLE I OF THE WORKFORCE INVESTMENT ACT Delivery of Adult and Dislocated Worker Services Through the One-Stop Delivery System § 663.105 When must...

  4. 20 CFR 663.105 - When must adults and dislocated workers be registered?

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 20 Employees' Benefits 4 2014-04-01 2014-04-01 false When must adults and dislocated workers be... LABOR (CONTINUED) ADULT AND DISLOCATED WORKER ACTIVITIES UNDER TITLE I OF THE WORKFORCE INVESTMENT ACT Delivery of Adult and Dislocated Worker Services Through the One-Stop Delivery System § 663.105 When must...

  5. 20 CFR 663.105 - When must adults and dislocated workers be registered?

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 20 Employees' Benefits 4 2013-04-01 2013-04-01 false When must adults and dislocated workers be... LABOR (CONTINUED) ADULT AND DISLOCATED WORKER ACTIVITIES UNDER TITLE I OF THE WORKFORCE INVESTMENT ACT Delivery of Adult and Dislocated Worker Services Through the One-Stop Delivery System § 663.105 When must...

  6. Upper extremity interaction with a helicopter side airbag: injury criteria for dynamic hyperextension of the female elbow joint.

    PubMed

    Duma, Stefan M; Hansen, Gail A; Kennedy, Eric A; Rath, Amber L; McNally, Craig; Kemper, Andrew R; Smith, Eric P; Brolinson, P Gunnar; Stitzel, Joel D; Davis, Martin B; Bass, Cameron R; Brozoski, Frederick T; McEntire, B Joseph; Alem, Nabih M; Crowley, John S

    2004-11-01

    This paper describes a three part analysis to characterize the interaction between the female upper extremity and a helicopter cockpit side airbag system and to develop dynamic hyperextension injury criteria for the female elbow joint. Part I involved a series of 10 experiments with an original Army Black Hawk helicopter side airbag. A 5(th) percentile female Hybrid III instrumented upper extremity was used to demonstrate side airbag upper extremity loading. Two out of the 10 tests resulted in high elbow bending moments of 128 Nm and 144 Nm. Part II included dynamic hyperextension tests on 24 female cadaver elbow joints. The energy source was a drop tower utilizing a three-point bending configuration to apply elbow bending moments matching the previously conducted side airbag tests. Post-test necropsy showed that 16 of the 24 elbow joint tests resulted in injuries. Injury severity ranged from minor cartilage damage to more moderate joint dislocations and severe transverse fractures of the distal humerus. Peak elbow bending moments ranged from 42.4 Nm to 146.3 Nm. Peak bending moment proved to be a significant indicator of any elbow injury (p = 0.02) as well as elbow joint dislocation (p = 0.01). Logistic regression analyses were used to develop single and multiple variate injury risk functions. Using peak moment data for the entire test population, a 50% risk of obtaining any elbow injury was found at 56 Nm while a 50% risk of sustaining an elbow joint dislocation was found at 93 Nm for the female population. These results indicate that the peak elbow bending moments achieved in Part I are associated with a greater than 90% risk for elbow injury. Subsequently, the airbag was re-designed in an effort to mitigate this as well as the other upper extremity injury risks. Part III assessed the redesigned side airbag module to ensure injury risks had been reduced prior to implementing the new system. To facilitate this, 12 redesigned side airbag deployments were conducted

  7. Dislocated Shoulder: Symptoms and Causes

    MedlinePlus

    ... arm bone pops out of the cup-shaped socket that's part of your shoulder blade. The shoulder ... your upper arm bone out of your shoulder socket. Partial dislocation — in which your upper arm bone ...

  8. Non-Traumatic Anterior Dislocation of a Total Knee Replacement Associated with Neurovascular Injury

    PubMed Central

    Aderinto, Joseph; Gross, Allan E; Rittenhouse, Bryan

    2009-01-01

    Prosthetic total knee replacements rarely dislocate. When dislocation does occur, it is usually in a posterior direction in association with a posterior stabilised, cruciate-sacrificing prosthesis. Neurovascular injury is unusual. In this report, we describe a case of anterior dislocation of a cruciate-retaining total knee replacement in a 67-year-old woman. The dislocation occurred in the absence of overt trauma and resulted in severe neurovascular injury. PMID:19686618

  9. [A clinical study and analysis of congenital lenticular dislocation (35 cases)].

    PubMed

    Guo, X; Mao, W; Chen, Y; Ma, Q; Zeng, L; Luo, T

    1991-12-01

    Thirty-five cases of congenital lenticular dislocation seen in our Center since 1985 have been studied and analyzed clinically. By the survey of pedigrees and examination of these patients, including ocular, systemic, skeletal X-ray, psychocardiogram, and urinary sodium-nitroprusside test, 21 cases were diagnosed as Marfan's syndrome, 6 cases as simple ectopia lentis, 3 cases as Weill-Marchesani's syndrome, 4 cases as aniridia and 1 case as homecys tinuria. We found that the most significant ocular manifestation of congenital lenticular dislocation was reduction in visual acuity. The severity of visual disturbance varied with the types of dislocation and the visual deficiency was closely related to the intermediate-grade (II) dislocation of the lens. Examination of ERG showed normal function in most of the patients. From this, we believe that the major cause of visual reduction in congenital lenticular dislocation is lenticular myopia and astigmatism. There fore, early diagnosis and effective correction of vision should be emphasized to prevent the occurrence of amblyopia.

  10. Free energy change of a dislocation due to a Cottrell atmosphere

    NASA Astrophysics Data System (ADS)

    Sills, R. B.; Cai, W.

    2018-06-01

    The free energy reduction of a dislocation due to a Cottrell atmosphere of solutes is computed using a continuum model. We show that the free energy change is composed of near-core and far-field components. The far-field component can be computed analytically using the linearized theory of solid solutions. Near the core the linearized theory is inaccurate, and the near-core component must be computed numerically. The influence of interactions between solutes in neighbouring lattice sites is also examined using the continuum model. We show that this model is able to reproduce atomistic calculations of the nickel-hydrogen system, predicting hydride formation on dislocations. The formation of these hydrides leads to dramatic reductions in the free energy. Finally, the influence of the free energy change on a dislocation's line tension is examined by computing the equilibrium shape of a dislocation shear loop and the activation stress for a Frank-Read source using discrete dislocation dynamics.

  11. Three-dimensional imaging of dislocation propagation during crystal growth and dissolution

    PubMed Central

    Schenk, Anna S.; Kim, Yi-Yeoun; Kulak, Alexander N.; Campbell, James M.; Nisbet, Gareth; Meldrum, Fiona C.; Robinson, Ian K.

    2015-01-01

    Atomic level defects such as dislocations play key roles in determining the macroscopic properties of crystalline materials 1,2. Their effects range from increased chemical reactivity 3,4 to enhanced mechanical properties 5,6. Dislocations have been widely studied using traditional techniques such as X-ray diffraction and optical imaging. Recent advances have enabled atomic force microscopy to study single dislocations 7 in two-dimensions (2D), while transmission electron microscopy (TEM) can now visualise strain fields in three-dimensions (3D) with near atomic resolution 8–10. However, these techniques cannot offer 3D imaging of the formation or movement of dislocations during dynamic processes. Here, we describe how Bragg Coherent Diffraction Imaging (BCDI) 11,12 can be used to visualize in 3D, the entire network of dislocations present within an individual calcite crystal during repeated growth and dissolution cycles. These investigations demonstrate the potential of BCDI for studying the mechanisms underlying the response of crystalline materials to external stimuli. PMID:26030304

  12. Field Dislocation Mechanics for heterogeneous elastic materials: A numerical spectral approach

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Djaka, Komlan Senam; Villani, Aurelien; Taupin, Vincent

    Spectral methods using Fast Fourier Transform (FFT) algorithms have recently seen a surge in interest in the mechanics of materials community. The present work addresses the critical question of determining accurate local mechanical fields using FFT methods without artificial fluctuations arising from materials and defects induced discontinuities. Precisely, this work introduces a numerical approach based on intrinsic discrete Fourier transforms for the simultaneous treatment of material discontinuities arising from the presence of dislocations and from elastic stiffness heterogeneities. To this end, the elasto-static equations of the field dislocation mechanics theory for periodic heterogeneous materials are numerically solved with FFT inmore » the case of dislocations in proximity of inclusions of varying stiffness. An optimal intrinsic discrete Fourier transform method is sought based on two distinct schemes. A centered finite difference scheme for differential rules are used for numerically solving the Poisson-type equation in the Fourier space, while centered finite differences on a rotated grid is chosen for the computation of the modified Fourier–Green’s operator associated with the Lippmann–Schwinger-type equation. By comparing different methods with analytical solutions for an edge dislocation in a composite material, it is found that the present spectral method is accurate, devoid of any numerical oscillation, and efficient even for an infinite phase elastic contrast like a hole embedded in a matrix containing a dislocation. The present FFT method is then used to simulate physical cases such as the elastic fields of dislocation dipoles located near the matrix/inclusion interface in a 2D composite material and the ones due to dislocation loop distributions surrounding cubic inclusions in 3D composite material. In these configurations, the spectral method allows investigating accurately the elastic interactions and image stresses due to dislocation

  13. Field Dislocation Mechanics for heterogeneous elastic materials: A numerical spectral approach

    DOE PAGES

    Djaka, Komlan Senam; Villani, Aurelien; Taupin, Vincent; ...

    2017-03-01

    Spectral methods using Fast Fourier Transform (FFT) algorithms have recently seen a surge in interest in the mechanics of materials community. The present work addresses the critical question of determining accurate local mechanical fields using FFT methods without artificial fluctuations arising from materials and defects induced discontinuities. Precisely, this work introduces a numerical approach based on intrinsic discrete Fourier transforms for the simultaneous treatment of material discontinuities arising from the presence of dislocations and from elastic stiffness heterogeneities. To this end, the elasto-static equations of the field dislocation mechanics theory for periodic heterogeneous materials are numerically solved with FFT inmore » the case of dislocations in proximity of inclusions of varying stiffness. An optimal intrinsic discrete Fourier transform method is sought based on two distinct schemes. A centered finite difference scheme for differential rules are used for numerically solving the Poisson-type equation in the Fourier space, while centered finite differences on a rotated grid is chosen for the computation of the modified Fourier–Green’s operator associated with the Lippmann–Schwinger-type equation. By comparing different methods with analytical solutions for an edge dislocation in a composite material, it is found that the present spectral method is accurate, devoid of any numerical oscillation, and efficient even for an infinite phase elastic contrast like a hole embedded in a matrix containing a dislocation. The present FFT method is then used to simulate physical cases such as the elastic fields of dislocation dipoles located near the matrix/inclusion interface in a 2D composite material and the ones due to dislocation loop distributions surrounding cubic inclusions in 3D composite material. In these configurations, the spectral method allows investigating accurately the elastic interactions and image stresses due to dislocation

  14. Hazardous and Medical Waste Destruction Using the AC Plasmatron Final Report CRADA No. TC-1560-98

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Caplan, M.; Bucher, K.; Tulupov, A.

    The goal of this project was to develop a prototype medical waste destruction facility based on the AC plasma torch capable of processing 150 kg of waste per hour while satisfying US EPA emission standards. The project was to provide the first opportunity for a joint U.S.-Russian project using an AC Plasma Torch in a hazardous waste destruction system to be assembled and operated in the U.S. thus promoting the commercialization in the U.S. of this joint U.S.-Russian developed technology. This project was a collaboration between the Russian Institute Soliton- NTT, the U.S industrial partner Scientific Utilization Inc. (SUI) andmore » Lawrence Livermore National Laboratory ( LLNL). The project was funded by DOE for a total of $1.2 million with $600K for allocated for Phase I and $600K for Phase II. The Russian team received about $800K over the two (2) year period while LLNL received $400K. SUI was to provide in kind matching funds totaling $1.2 million.« less

  15. Novel Cross-Slip Mechanism of Pyramidal Screw Dislocations in Magnesium.

    PubMed

    Itakura, Mitsuhiro; Kaburaki, Hideo; Yamaguchi, Masatake; Tsuru, Tomohito

    2016-06-03

    Compared to cubic metals, whose primary slip mode includes twelve equivalent systems, the lower crystalline symmetry of hexagonal close-packed metals results in a reduced number of equivalent primary slips and anisotropy in plasticity, leading to brittleness at the ambient temperature. At higher temperatures, the ductility of hexagonal close-packed metals improves owing to the activation of secondary ⟨c+a⟩ pyramidal slip systems. Thus, understanding the fundamental properties of corresponding dislocations is essential for the improvement of ductility at the ambient temperature. Here, we present the results of large-scale ab initio calculations for ⟨c+a⟩ pyramidal screw dislocations in magnesium and show that their slip behavior is a stark counterexample to the conventional wisdom that a slip plane is determined by the stacking fault plane of dislocations. A stacking fault between dissociated partial dislocations can assume a nonplanar shape with a negligible energy cost and can migrate normal to its plane by a local shuffling of atoms. Partial dislocations dissociated on a {21[over ¯]1[over ¯]2} plane "slither" in the {011[over ¯]1} plane, dragging the stacking fault with them in response to an applied shear stress. This finding resolves the apparent discrepancy that both {21[over ¯]1[over ¯]2} and {011[over ¯]1} slip traces are observed in experiments while ab initio calculations indicate that dislocations preferably dissociate in the {21[over ¯]1[over ¯]2} planes.

  16. Full characterization of dislocations in ion-irradiated polycrystalline UO2

    NASA Astrophysics Data System (ADS)

    Onofri, C.; Legros, M.; Léchelle, J.; Palancher, H.; Baumier, C.; Bachelet, C.; Sabathier, C.

    2017-10-01

    In order to fully characterize the dislocation loops and lines features (Burgers vectors, habit/slip planes, interstitial or vacancy type) induced by irradiation in UO2, polycrystalline thin foils were irradiated with 4 MeV Au or 390 keV Xe ions at different temperatures (25, 600 and 800 °C) and fluences (0.5 and 1 × 1015 ions/cm2), and further analyzed using TEM. In all the cases, this study, performed on a large number of dislocation loops (diameter ranging from 10 to 80 nm) and for the first time on several dislocation lines, reveals unfaulted prismatic dislocation loops with an interstitial nature and Burgers vectors only along the <110>-type directions. Almost 60% of the studied loops are purely prismatic type and lie on {110} habit planes perpendicular to the Burgers vector directions. The others lie on the {110} or {111} planes, which are neither perpendicular to the Burgers vectors, nor contain them. About 87% of the dislocation lines, formed by loop overlapping as fluence increases, are edge or mixed type in the <100>{100} slip systems, as those induced under mechanical load.

  17. 20 CFR 663.105 - When must adults and dislocated workers be registered?

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 20 Employees' Benefits 3 2011-04-01 2011-04-01 false When must adults and dislocated workers be... LABOR ADULT AND DISLOCATED WORKER ACTIVITIES UNDER TITLE I OF THE WORKFORCE INVESTMENT ACT Delivery of Adult and Dislocated Worker Services Through the One-Stop Delivery System § 663.105 When must adults and...

  18. Women and Plant Closings: Unemployment, Reemployment, and Job Training Enrollment Following Dislocation.

    ERIC Educational Resources Information Center

    Smith, Suzanna D.; Price, Sharon J.

    Thousands of workers have been dislocated from jobs in the textile and apparel industries as a result of recessions and structural changes in the economy. Because of the large concentrations of female workers in these industries, women have been particularly vulnerable to dislocation. This study examined job dislocation and factors that affect…

  19. Anisotropic Dislocation Line Energy and Crack Tip Dislocation Nucleation in (alpha)RDX

    DTIC Science & Technology

    2013-11-01

    Mitchell, R.L.; Knap, J.; Chung, P.W., Role of molecule flexibility on the nucleation of dislocations in molecular crystals. App. Phys. Lett. 2013...uniform stres , under-estimate of stressses (Get from S) Br=0; for i=1:3 Br=Br+sum(S(i,1:3)); end Br=1/Br; % Shear Modulus Gr=4/15*(S(1,1

  20. Theory of electron-phonon-dislon interacting system—toward a quantized theory of dislocations

    NASA Astrophysics Data System (ADS)

    Li, Mingda; Tsurimaki, Yoichiro; Meng, Qingping; Andrejevic, Nina; Zhu, Yimei; Mahan, Gerald D.; Chen, Gang

    2018-02-01

    We provide a comprehensive theoretical framework to study how crystal dislocations influence the functional properties of materials, based on the idea of a quantized dislocation, namely a ‘dislon’. In contrast to previous work on dislons which focused on exotic phenomenology, here we focus on their theoretical structure and computational power. We first provide a pedagogical introduction that explains the necessity and benefits of taking the dislon approach and why the dislon Hamiltonian takes its current form. Then, we study the electron-dislocation and phonon-dislocation scattering problems using the dislon formalism. Both the effective electron and phonon theories are derived, from which the role of dislocations on electronic and phononic transport properties is computed. Compared with traditional dislocation scattering studies, which are intrinsically single-particle, low-order perturbation and classical quenched defect in nature, the dislon theory not only allows easy incorporation of quantum many-body effects such as electron correlation, electron-phonon interaction, and higher-order scattering events, but also allows proper consideration of the dislocation’s long-range strain field and dynamic aspects on equal footing for arbitrary types of straight-line dislocations. This means that instead of developing individual models for specific dislocation scattering problems, the dislon theory allows for the calculation of electronic structure and electrical transport, thermal transport, optical and superconducting properties, etc, under one unified theory. Furthermore, the dislon theory has another advantage over empirical models in that it requires no fitting parameters. The dislon theory could serve as a major computational tool to understand the role of dislocations on multiple materials’ functional properties at an unprecedented level of clarity, and may have wide applications in dislocated energy materials.