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Sample records for ac joint dislocation

  1. Arthroscopic reconstruction of chronic AC joint dislocations by transposition of the coracoacromial ligament augmented by the Tight Rope device: a technical note.

    PubMed

    Hosseini, Hamid; Friedmann, Svenja; Tröger, Markus; Lobenhoffer, Philipp; Agneskirchner, Jens D

    2009-01-01

    We present a new arthroscopic technique for chronic AC joint dislocations with coracoacromial ligament transposition and augmentation by the Tight Rope device (Arthrex, Naples, USA). First the glenohumeral joint is visualised to repair concomitant lesions, such as SLAP lesions, if needed. Once the rotator interval is opened and the coracoid is identified, the arthroscope is moved to an additional anterolateral portal. A 1.5 cm incision is made 2 cm medial to the AC joint. After drilling a 4 mm hole with a cannulated drill through the clavicle and coracoid a Tight Rope is inserted, the clavicule is reduced and stabilized with the implant. The arthroscope is moved to the subacromial space and a partial bursectomy is performed to visualise the CA ligament and lateral clavicle. The CA ligament is armed with a strong braided suture using a Lasso stitch and dissected from the undersurface of the acromion. It is then reattached to the distal part of the clavicle by transosseous suture fixation after abrasion of its undersurface. Although this combined arthroscopic procedure of AC joint augmentation with a Tight Rope combined with a ligament transposition is technically demanding, it is a safe method to reconstruct the coracoclavicular ligaments and achieve a sufficient reduction of the clavicle without the need of further implant removal or autologous tendon transplantation.

  2. Dislocation

    MedlinePlus

    Joint dislocation ... It may be hard to tell a dislocated joint from a broken bone . Both are emergencies that ... to repair a ligament that tears when the joint is dislocated is needed. Injuries to nerves and ...

  3. Intrauterine Temporomandibular Joint Dislocation: Prenatal Sonographic Evaluation

    PubMed Central

    Çil, Ahmet Said; Bozkurt, Murat; Bozkurt, Duygu Kara

    2014-01-01

    Congenital temporomandibular joint (TMJ) diseases are very rare disorders and are usually diagnosed in childhood. Developmental disorders of the TMJ such as hypoplasia, hyperplasia, and aplasia of the TMJ compartments are characterized by TMJ dysfunction. In childhood, these patients experience recurrent dislocation, pain, and malocclusion. We present the case of a 25-week fetus with unilateral TMJ dislocation with fluid retention in the joint diagnosed by ultrasonography. To the best of our knowledge, this is the first case of TMJ dislocation diagnosed by ultrasonographic evaluation during the prenatal period. PMID:23669613

  4. [Posterior dislocation of the sternoclavicular joint].

    PubMed

    Mäkinen, Tatu; Madanat, Rami; Heinänen, Mikko; Brinck, Tuomas; Pajarinen, Jarkko

    2013-01-01

    Posterior dislocation of the sternoclavicular joint is a rare injury. It can be associated with life-threatening complications. Computed tomography is the imaging modality of choice with which possible associated injuries can be detected. Acute injuries are managed with closed reduction under general anaesthesia. A fracture-dislocation is inherently more unstable than an isolated dislocation. Surgical treatment is advocated in cases of delayed diagnosis or failed closed reduction. With early diagnosis and treatment, the long-term outcome of this injury is good.

  5. [Bilateral Asymmetric Traumatic Dislocation of Hip Joints].

    PubMed

    Paša, L; Veselý, R; Kelbl, M

    2017-01-01

    The authors present a rare case of bilateral asymmetric traumatic dislocation of hip joints, where the left joint was treated conservatively after the reduction, while the right joint, with an acetabular fragment interposition, was treated surgically - by arthroscopically assisted reduction and fixation of an osteochondral fragment of posterior wall of the acetabulum. The female patient healed with no complications, showing an excellent clinical outcome with no signs of instability or limited mobility of hip joints, and also with no signs of para-articular calcification or necrosis of the hip at 1 year after the injury and treatment. Bilateral asymmetric dislocation of hip joint is a rare injury with the total incidence of 150 cases as reported by the literature. Recently, its incidence is higher due to the increased traffic and the associated accident rate. A precise and prompt reduction of the injured hip joint is always necessary, if possible under general anesthesia. Also, it is always necessary to carry out a complete examination of the patient since this type of injury is always caused by a strong force and is often accompanied by injuries of other parts of the body. Key words: bilateral asymmetric dislocation of hip joints, hip arthroscopy, acetabular fracture.

  6. [Habitual dislocation of the temporomandibular joint].

    PubMed

    Hjortdal, O

    1975-02-01

    A case of recurrent dislocation of the left temporamandibular joint is reported. Different methods of treatment are reviewed. The present case was successfully treated with a combination of two methods: 1. Restriction of excessive condylar movement by means of continuous loop wiring and intermaxillary monofilament fishing line. 2. Intra-articular injections of autologous blood.

  7. Metatarsal Shaft Fracture with Associated Metatarsophalangeal Joint Dislocation

    PubMed Central

    2016-01-01

    Metatarsophalangeal joint dislocations of lesser toes are often seen in the setting of severe claw toes. Traumatic irreducible dislocations have been reported in rare cases following both low-energy and high-energy injuries to the forefoot. In this case report, I present a previously unreported association of a metatarsal shaft fracture with metatarsophalangeal joint dislocation of a lesser toe. PMID:27597914

  8. Ulnopalmar dislocation of the fifth carpometacarpal joint. A rare injury.

    PubMed

    Fischer, J W; Waseem, M; Gambhir, A; Creedon, R J

    2002-04-01

    Volar dislocation of the carpometacarpal joint of the little finger is an uncommon injury. It is subdivided in ulnopalmar and radiopalmar dislocations. The injury can easily be missed on standard x-rays. Closed reduction and K-wire fixation has commonly been used in the treatment, although closed reduction and casting has been reported. Only 10 cases of an ulnopalmar dislocation were published previously. We report a case of a simultaneous dislocation of the 4th metacarpophalangeal joint and an ulnopalmar dislocation of the 5th carpometacarpal joint. The combination of these injuries has not been reported yet. We review the available literature and discuss the methods of treatment.

  9. Ligamentous and capsular restraints to experimental posterior elbow joint dislocation.

    PubMed

    Deutch, Søren R; Olsen, Bo S; Jensen, Steen L; Tyrdal, Stein; Sneppen, Otto

    2003-10-01

    Pathological external forearm rotation (PEFR) relates to posterolateral elbow joint instability, and is considered a possible requisite step in a simple posterior elbow joint dislocation. The aim of this study was to evaluate the capsuloligamentous restraint to PEFR. In all, 18 elbow joint specimens were examined in a joint analysis system developed for experimental elbow dislocation. Sequential cutting of capsule and ligaments followed by stability testing provided specific data relating to each capsuloligamentous structure. The primary stabilizers against PEFR in the extended elbow were the anterior capsule and the lateral collateral ligament complex (LCLC), whereas in the flexed elbow the anterior capsule did not have a stabilizing effect. In flexed joint positions, the LCLC seems to be the only immediate stabilizer against PEFR, and thereby against posterolateral instability and possibly against posterior dislocation. The medial collateral ligament did not have any immediate stabilizing effect, but it prevented the final step of the posterior dislocation.

  10. Non-reducible palmar dislocation of the distal radioulnar joint

    PubMed Central

    Zannou, Rupestre S.; Rezzouk, Joel; Ruijs, Aleid C.J.

    2015-01-01

    Abstract A rare case of an isolated traumatic palmar dislocation of the distal radioulnar joint is presented. Clinically, there is a loss of pronation and supination. The dislocation was treated using an open reduction, reinsertion of the capsule-ligamentous complex and temporary stabilization using K-wires. PMID:26158121

  11. Dislocations

    MedlinePlus

    ... Attempting to move or jam a dislocated bone back in can damage blood vessels, muscles, ligaments, and nerves. Apply an ice pack. Ice can ease swelling and pain in and around the joint. Use ibuprofen or ...

  12. Posterior dislocation of the sternoclavicular joint: report of two cases.

    PubMed

    Labronici, Pedro José; Souza, Fabrício Cardoso de; Pires, Robinson Esteves Santos; Santos Filho, Fernando Claudino Dos; Gameiro, Vinicius Schott; Labronici, Gustavo José

    2016-01-01

    The authors report the cases of two young patients who had suffered a sporting accident with posterior traumatic dislocation of sternoclavicular joint. In one of the patients closed reduction was accomplished by keeping the limb in a sling. The second patient, after reduction was done, presented recurrence of the dislocation, thus requiring surgical treatment. It is important to observe the relevance of computed tomography to help diagnosing, as well as monitoring the reduction procedure. The objective of this study was to demonstrate two different types of treatment in a rare injury such as the posterior dislocation of sternoclavicular joint.

  13. [How I Treat. An Anterior Temporomandibular Joint Dislocation].

    PubMed

    Gilon, Y; Johnen, J; Nizet, J L

    2015-09-01

    Anterior dislocation of the temporomandibular joint is not uncommon and requires prompt management. A defect of dislocation reduction can lead to severe functional impairment of a complex, and often active joint. The diagnosis is clinical and relatively obvious. It is made by the frontline medical team, general practitioner or emergency doctor. Recurrent cases are a matter for maxillofacial surgeons. This article describes a conventional technique for anterior dislocation reduction, to achieve urgently. The second part of the article deals with the specialized surgical treatment of relapsing forms.

  14. 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

  15. 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.

  16. [Modern ideas on the treatment of dislocations and fracture-dislocations in the elbow joint].

    PubMed

    Dul'tsev, I A; Zhabin, G I; Neverov, V A

    2005-01-01

    The authors describe the causes and surgical methods of treatment of fresh and long-standing dislocations and fracture-dislocations in the elbow joint. The indications to using different operative methods and technical-surgical interventions are described in details as well as long-term results of treatment by the literature data. The current methods and the authors' methods of prophylactics and treatment of postoperative complications are analyzed. The methods of rehabilitation of such patients are also described.

  17. Abduction dislocation of the knee joint--a case study.

    PubMed

    Wójcik, Krzysztof; Bielecki, Tomasz; Polak, Damian; Skowron, Lukasz

    2013-10-31

    The paper presents a case of untypical, not included in existing classifications, knee joint dislocation in a young man. An MRI scan confirmed a rupture of both cruciate ligaments and damage to the ligamento-capsular complex on the medial side of the knee joint. Two weeks after injury, an arthroscopy was performed with joint lavage followed by repair of the damaged ligamento-capsular complex. A very good functional result was obtained three years after the injury, in spite of the patient not having consented to an elective cruciate ligament reconstruction.

  18. Acute Dislocation of the Metacarpal-Trapezoid Joint.

    PubMed

    Cardozo, Diego Fernando Rincón; Plata, Guillermo Varón; Casas, Jairo Antonio Camacho; Rodríguez, Natalia Sauza

    2016-06-01

    The trapezoid metacarpal dislocation is a rare event. In the literature, it is found in case reports. This injury is caused by direct or indirect high energy trauma. In most cases, the dislocation is dorsal and is difficult to reproduce because the joint is not very mobile. Given the low incidence and little evidence supported in the literature regarding the management, this injury can be treated by open or closed reduction; however, it has been published that most authors use Kirschner wire fixation with good results. Here we present our experience in the management of a male patient with acute trapezoid metacarpal dislocation handled with a splint with good functional results at 6 weeks.

  19. Acute Dislocation of the Metacarpal-Trapezoid Joint

    PubMed Central

    Plata, Guillermo Varón; Casas, Jairo Antonio Camacho; Rodríguez, Natalia Sauza

    2016-01-01

    The trapezoid metacarpal dislocation is a rare event. In the literature, it is found in case reports. This injury is caused by direct or indirect high energy trauma. In most cases, the dislocation is dorsal and is difficult to reproduce because the joint is not very mobile. Given the low incidence and little evidence supported in the literature regarding the management, this injury can be treated by open or closed reduction; however, it has been published that most authors use Kirschner wire fixation with good results. Here we present our experience in the management of a male patient with acute trapezoid metacarpal dislocation handled with a splint with good functional results at 6 weeks. PMID:27247751

  20. Posterior dislocation of the sternoclavicular joint leading to mediastinal compression.

    PubMed

    Jougon, J B; Lepront, D J; Dromer, C E

    1996-02-01

    Dislocations of the sternoclavicular joint are uncommon, and the posterior variety have a potential for considerable morbidity. We report a case with compression of the vital structures within the superior mediastinum. It was a rugby player getting run over by the scrum. The mechanism was an indirect force exerted forward and laterally against the shoulder. The patient complained of pain and dysphagia. A systolic right cervical murmur was heard. Angiography was normal and esophagography showed extrinsic esophageal compression. Surgical reduction was performed because there was a slight pneumomediastinum on the computed tomography. This case report demonstrates the mechanism, complications, and treatment of such a lesion.

  1. Anterior Dislocation of Elbow Joint-Case Report of A Rare Injury

    PubMed Central

    Kumar, Rakesh; Sekhawat, Vishal; Sankhala, SS; Bijarnia, Isha

    2014-01-01

    Introduction: In view of the comparative frequency of posterior dislocations of the elbow, it is rather remarkable that anterior dislocations of that joint should be among the rarest of injuries. Authors report a case of acute anterior dislocation with old fracture of medial epicondyle. Case Report: 22 years old male presented with acute pain and tenderness with deformity of right elbow joint and inability to move the elbow joint after he fell down during an episode of seizure. There was no neurovascular deficit. Radiological examination confirmed anterior dislocation of elbow joint with an ununited medial epicondyle fracture. Elbow was reduced under general anesthesia in emergency operation theatre. Conclusion: Anterior dislocation of elbow is very rare. Early diagnosis and proper reduction of dislocation is key of normal functioning of elbow joint. PMID:27298973

  2. [Anterior dislocation of the elbow joint without peri-articular fracture in an adult].

    PubMed

    Chbani, B; Lahrach, K; Amar, M-F; Ibnlkadi, K; Elmoubaker, S; Bennani, A; Marzouki, A; Boutayeb, F

    2012-12-01

    In view of the comparative frequency of posterior dislocations of the elbow, it is rather remarkable that anterior dislocations of that joint should be among the rarest of injuries [1]. Our case is one of the first cases of anterior dislocation of the elbow without any periarticular fracture or pre-existing deformities around the elbow [2].

  3. Acromioclavicular joint dislocation with associated brachial plexus injury

    PubMed Central

    Gallagher, Charles Alexander; Blakeney, William; Zellweger, René

    2014-01-01

    We present the case of a 32-year-old female who sustained a left acromioclavicular (AC) joint type V injury and brachial plexus injury. The patient's AC joint injury was identified 6 days after she was involved in a motorbike accident where she sustained multiple other injuries. She required operative fixation of the AC joint using a locking compression medial proximal tibial plate. At 3 months post operatively, the patient was found to have a subluxed left shoulder as a result of an axonal injury to the upper trunk of the brachial plexus. In addition, the tibial plate had cut out. The plate was subsequently removed. At 8 months the glenohumeral articulation had been restored and the patient had clinically regained significant shoulder function. After 15 months the patient was pain free and could complete all her activities of daily living without impediment. She returned to playing competitive pool after 24 months. PMID:24855076

  4. Temporomandibular joint sounds and disc dislocations incidence after orotracheal intubation.

    PubMed

    Rodrigues, Estela T; Suazo, Iván C; Guimarães, Antonio S

    2009-01-01

    The aim of this study was to analyze the temporomandibular joint (TMJ) disc displacement and articular sounds incidence after orotracheal intubation. A prospective cohort study was conducted in the Hospital Universitário do Oeste do Paraná (HUOP), in Cascavel, Brazil. 100 patients (aged 14-74 years, mean 44 years), 34 male and 66 female, in need of surgical procedure with orotracheal intubation were evaluated. The anterior disc displacement with reduction incidence and the nonclassifiable sounds incidence by the Research Diagnostic Criteria Axis I was evaluated in all patients after orotracheal intubation. The patients was evaluated one day before and until two days after the procedure. Eight percent present with anterior disc displacement with reduction and 10% presented nonclassifiable sounds after the orotracheal intubation. There was no correlation of any kind regarding gender related influence in the incidence of disc dislocations (P = 0.2591) and TMJ sounds (P = 0.487). Although anterior disc dislocations and TMJ sounds after anesthetic with orotracheal intubation presented a low incidence (8%-10%), it is recommended that the evaluation of TMJ signs and symptoms be done before the anesthetic procedure to take care with susceptible patients manipulation.

  5. 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

  6. 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.

  7. Reconstruction of displaced acromio-clavicular joint dislocations using a triple suture-cerclage: description of a safe and efficient surgical technique

    PubMed Central

    2012-01-01

    Purpose In this retrospective study we investigated the clinical and radiological outcome after operative treatment of acute Rockwood III-V injuries of the AC-joint using two acromioclavicular (AC) cerclages and one coracoclavicular (CC) cerclage with resorbable sutures. Methods Between 2007 and 2009 a total of 39 patients fit the inclusion criteria after operative treatment of acute AC joint dislocation. All patients underwent open reduction and anatomic reconstruction of the AC and CC-ligaments using PDS® sutures (Polydioxane, Ethicon, Norderstedt, Germany). Thirty-three patients could be investigated at a mean follow up of 32±9 months (range 24–56 months). Results The mean Constant score was 94.3±7.1 (range 73–100) with an age and gender correlated score of 104.2%±6.9 (88-123%). The DASH score (mean 3.46±6.6 points), the ASES score (94.6±9.7points) and the Visual Analogue Scale (mean 0.5±0,6) revealed a good to excellent clinical outcome. The difference in the coracoclavicular distance compared to the contralateral side was <5 mm for 28 patients, between 5-10 mm for 4 patients, and more than 10 mm for another patient. In the axial view, the anterior border of the clavicle was within 1 cm (ventral-dorsal direction) of the anterior rim of the acromion in 28 patients (85%). Re-dislocations occured in three patients (9%). Conclusion Open AC joint reconstruction using AC and CC PDS cerclages provides good to excellent clinical results in the majority of cases. However, radiographically, the CC distance increased significantly at final follow up, but neither the amount of re-dislocation nor calcifications of the CC ligaments or osteoarthritis of the AC joint had significant influence on the outcome. Level of evidence Case series, Level IV PMID:23098339

  8. Dislocation of the temporomandibular joint meniscus: contrast arthrography vs. computed tomography

    SciTech Connect

    Thompson, J.R.; Christiansen, E.; Sauser, D.; Hasso, A.N.; Hinshaw, D.B. Jr.

    1985-01-01

    A prospective study to determine the accuracy of computed tomography (CT) for the diagnosis of dislocation of the temporomandibular joint (TMJ) meniscus was made by performing both CT and contrast arthrography on 18 joints suspected of meniscus dislocation. Arthography rather than surgery was chosen as the quality standard for comparing CT findings, as not all patients undergoing the studies underwent surgery. The results of each test were reported independently by the radiologist who obtained either all of the arthograms or all of the CT scans. For dislocation of the meniscus, there were excellent agreement between the two methods. CT seems to be nearly as accurate as arthrography for showing meniscus dislocation, is performed with lower x-ray exposure, and is noninvasive. Arthrograpy discloses more detailed information about the joint meniscus, such as perforation and maceration, and should continue to be used when this kind of information is clinically important.

  9. Treatment of Chronic Acromioclavicular Joint Dislocation in a Paraplegic Patient with the Weaver-Dunn Procedure and a Hook-Plate.

    PubMed

    Godry, Holger; Citak, Mustafa; Königshausen, Matthias; Schildhauer, Thomas A; Seybold, Dominik

    2016-06-27

    In case of patients with spinal cord injury and concomitant acromioclavicular (AC) joint-dislocation the treatment is challenging, as in this special patient group the function of the shoulder joint is critical because patients depend on the upper limb for mobilization and wheelchair-locomotion. Therefore the goal of this study was to examine, if the treatment of chronic AC-joint dislocation using the Weaver-Dunn procedure augmented with a hook-plate in patients with a spinal cord injury makes early postoperative wheelchair mobilization and the wheelchair transfer with full weight-bearing possible. In this case the Weaver-Dunn procedure with an additive hook-plate was performed in a 34-year-old male patient with a complete paraplegia and a posttraumatic chronic AC-joint dislocation. The patient was allowed to perform his wheelchair transfers with full weight bearing on the first post-operative day. The removal of the hook-plate was performed four months after implantation. At the time of follow-up the patient could use his operated shoulder with full range of motion without restrictions in his activities of daily living or his wheel-chair transfers.

  10. Clinical Outcome of Metacarpophalangeal Joint Dislocation of the Thumb in Children: Case Series of 10 Patients

    PubMed Central

    Khursheed, Omar; Haq, Ansarul; Rashid, Shakir; Manzoor, Nazeefa; Shiekh, Sarwar; Mushtaq, Muzaffar

    2016-01-01

    Objectives  Dislocation of the metacarpophalangeal joint of the thumb in children is an uncommon entity. The aim of this study was to evaluate the clinical outcome of pediatric patients with metacarpophalangeal joint dislocation of the thumb. Patients and Methods  Ten pediatric patients with metacarpophalangeal joint dislocation of the thumb were evaluated. Patients were studied prospectively over a period of 3 years. Parameters studied included patient demographics, type of dislocation, management, and any complications. Results  Mean age of patients was 6.8 years (range: 3–12 years). Seven patients underwent closed reduction and three patients were managed by open reduction. Of the total 10 patients, excellent results were obtained in 9 patients. One of the patients who reported on the fourth day of trauma and was managed by open reduction had mild joint stiffness with a range of motion of 10 to 40 degrees at final follow-up. None of these patients had infection or instability. Conclusion  After thorough clinical and radiological examination, closed reduction can be done in incomplete and simple complete dislocations of metacarpophalangeal joint of the thumb. Repeated closed reduction should be avoided in complex complete injuries. Early mobilization is advised to prevent joint stiffness. PMID:27616822

  11. Arthroscopic electrothermal capsulorrhaphy for the treatment of recurrent temporomandibular joint dislocation.

    PubMed

    Torres, Daniel E; McCain, Joseph P

    2012-06-01

    Acute temporomandibular joint dislocation is a common occurrence that is generally treated by conservative therapy. In some patients, this can become a chronic recurrent condition. This recurrent temporomandibular joint dislocation (RTD) can significantly decrease the patient's quality of life and require some form of surgical intervention for correction. The purpose of this study is to present a minimally invasive alternative treatment for RTD using operative arthroscopy. 11 patients treated for recurrent temporomandibular dislocation between 2004 and 2010 were retrospectively analyzed. Electrothermal capsulorrhaphy was performed using a standard double puncture operative arthroscopy with a Hol:YAG laser and/or electrocautery. Postoperatively the patients were monitored for 6 months to 6 years. Of the 11 subjects, 2 suffered a recurrence of temporomandibular dislocation and required open arthrotomy for correction. The other 9 patients had no signs of recurrence or any significant postoperative loss of function. Electrothermal capsulorrhaphy is an effective and minimally invasive method for the treatment of RTD.

  12. Classic article: foot & ankle 1:15, 1980 traumatic dislocations of the first metatarsophalangeal joint.

    PubMed

    Jahss, Melvin H

    2006-06-01

    The mechanics, anatomy, and pathomechanics of traumatic dorsal dislocation of the first metatarsophalangeal joint are discussed. There are two basic types of dislocations. In Type I, dislocation of the hallux with the sesamoids occurs without disrupting the sesamoid mass. Such cases are usually irreducible on closed reduction, the metatarsal head being incarcerated by the conjoined tendons with their intact sesamoids. In Type II, there is either associated disruption of the intersesamoid ligament (Type IIA) or a transverse fracture of one of the sesamoids (Type IIB). In Type II, the sesamoid disruption usually permits closed reduction.

  13. Judo-related traumatic posterior sternoclavicular joint dislocation in a child.

    PubMed

    Galanis, Nikiforos; Anastasiadis, Prodromos; Grigoropoulou, Foteini; Kirkos, John; Kapetanos, George

    2014-05-01

    Judo is a combat sport with high risk of injury. We present a rare case of traumatic left posterior sternoclavicular (SC) joint dislocation, inflicted to a 12-year-old boy during a judo contest. An extensive literature review did not reveal any case of posterior SC joint dislocation in judo. The patient was treated with closed reduction under general anesthesia. At 2-year follow-up, his left upper extremity had full range of motion, and he did not complain of any residual symptoms. He decided to discontinue judo training; however, he participates in other physically demanding sports. Although not often encountered, posterior SC joint dislocation is a challenging and critical medical problem that can be fatal if not promptly diagnosed and treated on time and should be considered in the differential diagnosis of trauma-related anterior chest pain.

  14. Mini hook plate fixation for palmar fracture-dislocation of the proximal interphalangeal joint.

    PubMed

    Komura, Shingo; Yokoi, Tatsuo; Nonomura, Hidehiko

    2011-04-01

    Fracture-dislocations of the proximal interphalangeal joint are challenging to treat, since it is difficult to achieve both rigid fixation and early joint motion simultaneously. Palmar fracture-dislocations of the proximal interphalangeal joint are less frequent injuries and a small number of treatment methods have been reported. We describe here a patient with a chronic palmar fracture-dislocation of the proximal interphalangeal joint, who was treated with a new surgical technique. In the surgery, a mini hook plate that was made by adapting a 1.5 mm AO hand modular system straight plate was used. Despite the thinness of the fragment, rigid fixation was achieved, resulting in early active motion. At final follow up, the active ranges of motion were 0°-100° at the proximal and 0°-80° at the distal interphalangeal joint, and there were no complications. This technique may become a useful surgical method to treat palmar fracture-dislocations of the proximal interphalangeal joint.

  15. 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

  16. Isolated radial volar dislocation of the fifth carpometacarpal joint :a rare injury

    PubMed Central

    El Kadi, Khalid Ibn; Sbiyaa, Mohcine; Alami, Badr; Rabhi, Ilyass; Marzouki, Amine; Lahrach, Kamal; Boutayeb, Fawzi

    2013-01-01

    Isolated palmar dislocation of the fifth carpometacarpal joint is an uncommon injury and classified as radio-palmar or ulno-palmar according to the direction of displacement of the fifth metacarpal base. This very rare injury is often difficult to recognize. A careful neurologic assessment of the patient is a necessity, as well as obtaining proper radiographs of the hand. The purpose of this report is to present a patient with a pure isolated volar dislocation of the fifth carpometacarpal joint that was satisfactorily treated with closed reduction and casting. A review of the literature is presented. PMID:24711880

  17. 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

  18. All-Arthroscopic Technique for Reconstruction of Acute Acromioclavicular Joint Dislocations

    PubMed Central

    Cutbush, Kenneth; Hirpara, Kieran M.

    2015-01-01

    Acromioclavicular joint dislocations are a common injury particularly among contact sports players. There has been an increasing trend toward arthroscopic management of these injuries. To date, these reconstructions have primarily addressed superoinferior instability by reconstructing the coracoclavicular ligaments. We describe an all-arthroscopic technique for reconstruction of the coracoclavicular ligaments using Arthrex ABS TightRopes (Arthrex, Naples, FL), with additional stabilization of the superior acromioclavicular joint capsule using an anchor-based suture bridge to address anteroposterior instability. PMID:26697307

  19. Floating thumb with double dislocation of carpometacarpal and metacarpo-phalangeal joints

    PubMed Central

    Rajeev, Aysha; Noureldin, Soliman; Graham, David

    2014-01-01

    INTRODUCTION Double dislocations of carpometacarpal and metacarpo-phanlageal joints are rare. We report an unusual case of simultaneous dislocation of both CMC and MCP joints in the thumb. PRESENTATION OF CASE A 31 year old male was admitted following a road traffic accident. He was complaining of pain and deformity of right thumb. The X-ray examination revealed simultaneous dislocation of both CMC and MCP joints. He underwent closed manipulative reduction and percutaneous K wire fixation. The wires were removed after six weeks. After a course of physiotherapy he regained full range of pain free movements. DISCUSSION The incidence of simultaneous dislocation of both CMC and MCP joints in thumb are associated with high energy injuries. The options of treatment are conservative with cast immobilisation and serial X-rays or operative including closed manipulative reduction and K wire fixation or open reduction and internal fixation. CONCLUSION The option of treating this rare injury with closed manipulative reduction and percutaneous K wiring gives excellent and predictable results. PMID:25437649

  20. Complex dorsal dislocation of the distal interphalangeal joint: Perspectives on management

    PubMed Central

    Sankaran, Ajeesh; Bharathi, R. Ravindra; Sabapathy, S. Raja

    2016-01-01

    Distal interphalangeal joint dislocations are only rarely complex and irreducible. We present a case and illustrate our approach to management of this problem. Open reduction is necessary, and preferred approach is volar. It is imperative to identify the injured soft tissue and repair them as is feasible. PMID:28216823

  1. A survey of temporomandibular joint dislocation: aetiology, demographics, risk factors and management in 96 Nigerian cases.

    PubMed

    Ugboko, V I; Oginni, F O; Ajike, S O; Olasoji, H O; Adebayo, E T

    2005-07-01

    A retrospective study of 96 cases of temporomandibular joint dislocation was undertaken. Patients' ages ranged from 9 to 85 years (mean+/-SD, 35.3+/-17.4 years) and peak incidence was at 20-29 years. Mean duration was 7.9 weeks (range, 1h to 3 years). Acute, chronic and recurrent dislocations were seen in 46 (47.9%), 29 (30.2%) and 21 (21.9%) patients, respectively. Males dominated in all three categories but this was not statistically significant (P = 0.8). Excessive mouth opening while yawning (44 cases) was the commonest cause of dislocation, followed by road traffic accidents (13 cases). Ten patients (10.4%) had an underlying systemic disease, the commonest being epilepsy (four cases); those with acute dislocation recorded the highest incidence of underlying illness. Bilateral anterior (86 cases) dislocations were the most frequent. Of the 96 patients, 89 (92.7%) were available for treatment. Manual reduction with or without anaesthesia proved effective for 38/45 acute, 5/24 chronic and 14/20 recurrent cases. Chronic dislocations were treated mainly by surgical osteotomy (13/24). Vertical subsigmoid and oblique ramus osteotomies were the commonest surgical techniques recorded. Treatment was satisfactory for all patients surgically handled except for one case of anterior open bite postoperatively. This study has shown that excessive mouth opening while yawning is the commonest cause of temporomandibular joint dislocation in Nigerians, and conservative approaches to management remain quite effective irrespective of the duration and clinical subtype. The best choice of surgical technique should be determined by proper clinical evaluation and the need to avoid or minimize postoperative morbidity.

  2. A comparison of ketamine versus etomidate for procedural sedation for the reduction of large joint dislocations

    PubMed Central

    Salen, Philip; Grossman, Michelle; Grossman, Michael; Milazzo, Anthony; Stoltzfus, Jill

    2016-01-01

    Study Objectives: Ketamine and etomidate are used for procedural sedation (PS) to facilitate the performance of painful procedures. We hypothesized that ketamine produces adequate and comparable sedation conditions for dislocated large joint reduction when compared to etomidate and results in fewer adverse events. Methods: This Institutional Review Board approved prospective trial compared a convenience sample of subjects, who were randomized to receive either ketamine or etomidate for PS to facilitate reduction of large joint dislocations. Following informed consent, subjects were assigned via a computer-generated algorithm to receive either etomidate (0.1 mg/kg) or ketamine (0.5 mg/kg) intravenously; if PS was not sufficient, subjects received repeat doses of etomidate or ketamine until adequate PS was achieved. The protocol's primary endpoint was a successful reduction of dislocated, large joints. Secondary endpoints included alteration in blood pressure, vomiting, recovery agitation, hypersalivation, laryngospasm, myoclonus, hypoxia, airway assistance with chin lift or jaw thrust, bag-valve-mask ventilation, endotracheal intubation, utilization of additional doses of ketamine or etomidate, and recovery time from sedation. Results: Total enrollment was eighty subjects, 46 in the ketamine cohort and 34 in the etomidate cohort. The two PS groups were comparable in terms of gender, age, and weight. There was no significant difference in the primary endpoint of large joint dislocation reduction between the ketamine and etomidate cohorts (46/46, 100%; 32/34, 94.1%; P – 0.1). Shoulder, hip, and ankle joints account for the majority of joint reductions in this trial. Titration of PS was necessary for almost half of each cohort as evidenced by the utilization of additional dosages of the sedative agents: ketamine (22/46, 47.8%) and etomidate (14/34, 41.2%; P – 0.56). Among secondary outcome variables, significant differences between ketamine and etomidate cohorts

  3. Functional reconstruction of the TM joint in cases of severely displaced fractures and fracture dislocation.

    PubMed

    Umstadt, H E; Ellers, M; Müller, H H; Austermann, K H

    2000-04-01

    In a clinical and axiographic study the outcome of patients with severely displaced fractures and fracture dislocations of the mandibular condyle was evaluated. Two operation methods were compared one via an intraoral approach without joint revision and another via a preauricular approach with open reduction of the joint. In the group with joint revision, resorbable material was used for osteosynthesis. Twenty-eight patients (32 joints) treated without revision of the joint and 26 patients (29 joints) with open reduction of the joint were evaluated. The mean observation time following surgery was 3 years and 10 months (range 1-7.5 years). Clinical examination utilized the Helkimo-index, while the electronic axiographical results were evaluated by using a five point scheme of joint-mobility. Concerning clinical evaluation, 20 out of 28 patients (71%) without joint revision and 23 out of 26 (89%) patients with joint revision had none or only slight dysfunction of the stomatognathic system. When focusing on arthralgia and pain in motion (part D and E of Helkimo's-index) significantly better results were achieved by open joint revision (Helkimo D: p< or =0.007; Helkimo E: p = 0.0029). No patient exhibited severe dysfunction (group D3). In axiographic evaluation optimal results (group A1) were achieved in seven joints (24%) with revision and four joints (12%) without revision. Twelve out of 29 joints with revision (41%) and six out of 32 joints without revision (19%) were classified as group A2 with a slightly shortened condylar excursion. Revision of joints with disc reduction and reconstruction of ligaments in cases of severely displaced or dislocated fractures resulted in better mobility and less pain. This was seen clinically and in the axiographic results. Looking at the long-term outcome of patients better mobility of the joint without internal derangement due to surgical repair also protects the contralateral (nonoperated) joint. When managing severe TMJ

  4. [Asymmetric bilateral traumatic dislocation of the hip joint: a case report].

    PubMed

    Azar, Nikola; Yalçinkaya, Merter; Akman, Yunus Emre; Uzümcügil, Onat; Kabukçuoğlu, Yavuz S

    2010-08-01

    Bilateral traumatic dislocation of the hip is a rare condition. Simultaneous asymmetric traumatic dislocation of the hip, one hip anterior and the other posterior, is even more unusual. This article reports a 21-year-old male patient with asymmetric bilateral dislocation of the hip joint, injured due to a landslide during a canal excavation. The patient was treated conservatively and evaluated according to Thompson and Epstein clinical and radiographic criteria after a follow-up period of 10 years and six months. The clinical result was perfect and radiographical result was good. We determined that our case had occurred as a result of a mechanism that has not been previously published in the literature and evaluated it from this point of view.

  5. Reduction of temporomandibular joint dislocation: an ancient technique that has stood the test of time.

    PubMed

    Forshaw, R J

    2015-07-01

    The first known recorded evidence for the reduction of a mandibular joint dislocation is documented in a papyrus dated to c. 1500 BC that originated from ancient Egypt. This same technique was later discussed by Hippocrates in Greece and the Hippocratic corpus is referred to in early Islamic writings. It is detailed in medieval European texts and eventually was incorporated into modern dental and medical practice. Today, mandibular joint dislocation is probably not that common but to be included in an important ancient Egyptian treatise, predominately concerned with trauma to the head and neck, could suggest it was a more frequent occurrence in antiquity. This could relate to the heavy tooth wear, frequent antemortem tooth loss and the related sequelae of severe malocclusion and overclosure evident in many surviving ancient Egyptian skulls.

  6. Temporomandibular joint dislocation reduction technique: a new external method vs. the traditional.

    PubMed

    Ardehali, Mojtaba Mohamadi; Kouhi, Ali; Meighani, Ali; Rad, Farshid Mahboubi; Emami, Hamed

    2009-08-01

    The traditional intraoral approach for temporomandibular joint dislocations reduction, although effective, has some disadvantages. Here, a new extraoral approach is described. This study was performed to evaluate this new method's success rate. Patients visiting an emergency room were randomly allocated to 2 groups; one group was reduced with the extraoral approach and the other with the intraoral method. Among 29 attempts with the conventional method, 25 were successful (86.2%; 95% confidence interval: 73-100) and among 29 attempts with the external method, 16 were successful (55.2%; 95% confidence interval: 39-79). This difference was statistically significant. Because of the benefits of the external approach, such as avoiding hand bites and disease transfer, it can be a reasonable choice to reduce a dislocated temporomandibular joint.

  7. Chronic acromioclavicular joint dislocations treated by the GraftRope device

    PubMed Central

    Nordin, Jonas S; Aagaard, Knut E; Lunsjö, Karl

    2015-01-01

    Background and purpose Surgical treatment of chronic acromioclavicular joint dislocations is challenging, and no single procedure can be considered to be the gold standard. In 2010, the GraftRope method (Arthrex Inc., Naples, FL) was introduced in a case series of 10 patients, showing good clinical results and no complications. We wanted to evaluate the GraftRope method in a prospective consecutive series. Patients and methods 8 patients with chronic Rockwood type III–V acromioclavicular joint dislocations were treated surgically using the GraftRope method. The patients were clinically evaluated and a CT scan was performed to assess the integrity of the repair. Results and interpretation In 4 of the 8 patients, loss of reduction was seen within the first 6 weeks postoperatively. A coracoid fracture was the reason in 3 cases and graft failure was the reason in 1 case. In 3 of the 4 patients with intact repairs, the results were excellent with no subjective shoulder disability 12 months postoperatively. It was our intention to include 30 patients in this prospective treatment series, but due to the high rate of complications the study was discontinued prematurely. Based on our results and other recent reports, we cannot recommend the GraftRope method as a treatment option for chronic acromioclavicular joint dislocations. PMID:25323800

  8. Biepicondylar fracture dislocation of the elbow joint concomitant with ulnar nerve injury

    PubMed Central

    Konya, M Nuri; Aslan, Ahmet; Sofu, Hakan; Yıldırım, Timur

    2013-01-01

    In this article, we present a case of humeral biepicondylar fracture dislocation concomitant with ulnar nerve injury in a seventeen year-old male patient. Physical examination of our patient in the emergency room revealed a painful, edematous and deformed-looking left elbow joint. Hypoesthesia of the little finger was also diagnosed on the left hand. Radiological assessment ended up with a posterior fracture dislocation of the elbow joint accompanied by intra-articular loose bodies. Open reduction-Internal fixation of the fracture dislocation and ulnar nerve exploration were performed under general anesthesia at the same session as surgical treatment of our patient. Physical therapy and rehabilitation protocol was implemented at the end of two weeks post-operatively. Union of the fracture lines, as well as the olecranon osteotomy site, was achieved at the end of four months post-operatively. Ulnar nerve function was fully restored without any sensory or motor loss. Range of motion at the elbow joint was 20-120 degrees at the latest follow-up. PMID:23610759

  9. Biepicondylar fracture dislocation of the elbow joint concomitant with ulnar nerve injury.

    PubMed

    Konya, M Nuri; Aslan, Ahmet; Sofu, Hakan; Yıldırım, Timur

    2013-04-18

    In this article, we present a case of humeral biepicondylar fracture dislocation concomitant with ulnar nerve injury in a seventeen year-old male patient. Physical examination of our patient in the emergency room revealed a painful, edematous and deformed-looking left elbow joint. Hypoesthesia of the little finger was also diagnosed on the left hand. Radiological assessment ended up with a posterior fracture dislocation of the elbow joint accompanied by intra-articular loose bodies. Open reduction-Internal fixation of the fracture dislocation and ulnar nerve exploration were performed under general anesthesia at the same session as surgical treatment of our patient. Physical therapy and rehabilitation protocol was implemented at the end of two weeks post-operatively. Union of the fracture lines, as well as the olecranon osteotomy site, was achieved at the end of four months post-operatively. Ulnar nerve function was fully restored without any sensory or motor loss. Range of motion at the elbow joint was 20-120 degrees at the latest follow-up.

  10. Invited Hand Article: Current Concepts in Treatment of Fracture-Dislocations of the Proximal Interphalangeal Joint

    PubMed Central

    Haase, Steven C.; Chung, Kevin C.

    2014-01-01

    Background Proximal interphalangeal joint fracture-dislocations are common injuries that require expedient and attentive treatment for the best outcomes. Management can range from protective splinting and early mobilization to complex operations. In this review, the current concepts surrounding the managment of these injuries are reviewed. Methods A literature review was performed of all recent articles pertaining to proximal interphalangeal joint fracture-dislocation, with specific focus on middle phalangeal base fractures. Where appropriate, older articles, or articles on closely related injury types were included for completeness. The methodology and outcomes of each study were analyzed. Results When small avulsion fractures are present, good results are routinely obtained with reduction and early mobilization of stable injuries. Strategies for management of the unstable dorsal fracture-dislocation have evolved over time. To provide early stability, a variety of techniques have evolved, including closed, percutaneous, external, and internal fixation methods. Although each of these techniques can be successful in skilled hands, none have been subjected to rigorous, prospective, comparative trials. Volar dislocations fare less well, with significant loss of motion in many studies. Pilon fractures represent the most complicated injuries, and return of normal motion is not expected. Conclusion The best outcomes can be achieved by (1) establishing enough stability to allow early motion, (2) restoring gliding joint motion rather than non-congruent motion, and (3) restoring the articular surface congruity when possible. Although the majority of literature on this topic consists of expert opinion and retrospective case series, the consensus appears to favor less invasive techniques whenever possible. PMID:25415092

  11. Post-surgical unilateral temporomandibular joint dislocation treated by open reduction followed by orthodontic treatment.

    PubMed

    Satake, H; Yamada, T; Kitamura, N; Yoshimura, T; Sasabe, E; Yamamoto, T

    2011-03-01

    A case of prolonged unilateral temporomandibular joint (TMJ) dislocation, which was treated by open surgical reduction and post-surgical orthodontic therapy, is presented. A 58-year-old woman presented complaining of facial asymmetry and malocclusion. She had received surgery for a malignant tumour in the right retromolar region 7 years previously. It was considered that contraction of the pterygoid muscle by surgical injury caused anterior meniscal displacement and TMJ dislocation. Since manual manipulation failed, direct open reduction was performed after separation of the lateral pterygoid muscle from the condylar head and removal of the intra-articular scar tissues. Although the condylar head was returned to the glenoid fossa, optimal occlusion was not obtained because of compensatory tooth movement and inclination. Satisfactory occlusion and symmetric facial appearance were brought about by post-surgical orthodontic therapy.

  12. Chronic temporomandibular joint dislocation by mandibular distraction in a patient with Melnick-needles syndrome.

    PubMed

    Kelley, Patrick; Mata, Carlos; Da Silveira, Adriana

    2010-01-01

    Melnick-Needles syndrome is a congenital syndrome associated with severe architectural disorder of the skeletal system that can cause significant effects on the craniofacial skeleton including the mandible and temporomandibular joint. We report on a case of a young adult patient who experienced chronic dislocation, pain, and dysfunction of her temporomandibular joints related to both a severe bite dysfunction (mandibular hypoplasia) and the underlying bony architectural disorder associated with Melnick-Needles syndrome. The patient underwent bilateral mandibular distraction to correct her skeletal malocclusion and improve the condylar relationship with the temporomandibular joint fossae. The inherent bony abnormalities presented unique challenges to distraction. The patient was successfully distracted using internal mandibular distractors, rhBMP-2, and a prolonged distraction protocol. The patient experienced complete resolution of symptoms and resumed an unrestricted diet 6 months after removal of devices and has been pain-free for more than 24 months.

  13. 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.

  14. Fracture-dislocations of the elbow joint--strategy for treatment and results.

    PubMed

    Lill, H; Korner, J; Rose, T; Hepp, P; Verheyden, P; Josten, C

    2001-01-01

    Between January 1993 and December 1996, 41 patients with fracture dislocation of the elbow joint were treated in our department. In 28 patients (median age 46 years, range 15-77 years; 16 male, 12 female), a clinical and radiological follow-up was obtained after median 34 months (range 12-59 months). In addition to the humero-ulnar dislocation, isolated fractures were present in 13 patients and combined fractures in 15 (all with involvement of the radial head). Primary neurological deficits were found in 7 and open fractures in 3 patients. In 7 patients, primary definitive surgical therapy was carried out by open reduction and internal fixation. A two-step surgical management (initial closed reduction and immobilization, 5 patients with external fixator, 7 with plaster; secondary open surgical procedure) was performed in 12 and conservative treatment in 9 patients. According to the Leipzig Elbow Score, taking subjective, clinical and radiological criteria into consideration, 4 patients achieved 'excellent' and 5 patients a 'good' result. Ten patients were scored 'moderate' and 9 'poor'. The rate of secondary complications necessitating revision was 36%. Poor results were primarily caused by extensive initial soft-tissue damage, delayed definitive surgical therapy, and ectopic heterotopic ossification. In contrast, fracture localization and degree of arthrosis were not of significant importance for the final outcome. In fracture dislocations, the goal is a primary definitive surgical treatment aiming for early postoperative physiotherapy.

  15. Anterior dislocation of the ulnar‐humeral joint in a so‐called ‘pulled elbow'

    PubMed Central

    Venkatram, N; Wurm, V; Houshian, S

    2006-01-01

    We describe an unusual case of a missed anterior dislocation of the elbow joint in a 1 year old girl who presented with a pulled elbow. To our knowledge, this is the first report of anterior dislocation as a result of a pulled elbow in the literature. We would like to highlight the rarity of this presentation and the importance of chronological assessment and management in the accident and emergency department. PMID:16714491

  16. Acromioclavicular and sternoclavicular joint injuries.

    PubMed

    Macdonald, Peter B; Lapointe, Pierre

    2008-10-01

    Acromioclavicular (AC) joint injuries are a frequent diagnosis following an acute shoulder injury. The literature on AC joint dislocation is extensive, reflecting the intense debate surrounding the topic. The choice of treatment is influenced by factors including the type of injury, the patient's occupation, the patient's past medical history, the acuity of the injury, and patient expectations. Sternoclavicular (SC) joint dislocation is an uncommon injury. The treatment of acute anterior SC joint dislocations is controversial. It is difficult to study with a well-designed prospective study because of the low frequency of this injury. Posterior dislocations are much less common than anterior dislocations. Posterior dislocations, however, are more serious; they are associated with significant complications and require prompt attention.

  17. Modified Leclerc blocking procedure with miniplates and temporal fascial flap for recurrent temporomandibular joint dislocation.

    PubMed

    Ying, Binbin; Hu, Jing; Zhu, Songsong

    2013-05-01

    This study introduced the modified Leclerc blocking procedure with miniplate and temporal fascial flap for recurrent temporomandibular joint (TMJ) dislocation and evaluated its clinical effects. Seven patients were treated by the modified Leclerc blocking procedure with miniplate and temporal fascial flap. The postoperative follow-up period ranged from half a year to 2 years to access the maximal mouth opening, TMJ disorder symptoms (pain and sound), and incidence of recurrence. No recurrence was observed in all of the 7 patients postoperatively. The mean preoperative and postoperative MMOs were 49.7 mm and 40.1 mm, respectively. There were 3 patients who reported the alleviation of pain and/or sound postoperatively. Two older patients with long-term course of disease reported no improvement of the TMJ symptoms in terms of pain and sound postoperatively. Our results showed that the modified Leclerc blocking procedure with miniplates and temporal fascial flap provided a more stable support for the condylar movement with less recurrence, suggesting that this operation could be a good alternative for the treatment of recurrent TMJ dislocation.

  18. Migration of a Broken Kirschner Wire after Surgical Treatment of Acromioclavicular Joint Dislocation

    PubMed Central

    Batın, Sabri; Gürbüz, Kaan; Uzun, Erdal; Kayalı, Cemil; Altay, Taşkın

    2016-01-01

    Kirschner wire (K-wire) is one of the commonly used implants in orthopaedics practice. Migration of the wire is one of the most frequently reported complications after fixation by the K-wire. In particular, it has been reported that a greater range of motion in the shoulder, negative intrathoracic pressure associated with respiration, gravitational force, and muscular activities may cause migration from the upper extremities. In general, thin and long foreign bodies with smooth surfaces that are localized within the tendon sheath and at an upper extremity can migrate more readily and can reach longer distances. Here, we present a patient with long-term migration of a broken K-wire who underwent fixation for acromioclavicular joint dislocation 5 years ago. PMID:28058127

  19. Unrecognized bilateral temporomandibular joint dislocation after general anesthesia with a delay in diagnosis and management: a case report

    PubMed Central

    2013-01-01

    Introduction Anterior bilateral temporomandibular joint dislocation is not an uncommon occurrence and has been reported before. However, its diagnosis can easily be overlooked, especially by clinicians who are unfamiliar with this pathology. Continuous discussion of the pathology is required to prevent delays in diagnosis, which can lead to long-term sequelae for the patient. Case presentation We present the case of a 66-year-old Somali woman who experienced a bilateral anterior temporomandibular joint dislocation after a general anesthetic for an exploratory laparotomy for excision of a pelvic sarcoma. She first presented in the intensive care unit with preauricular pain and an inability to close her mouth, and was initially misdiagnosed and treated for a muscle spasm. The cause of her misdiagnosis was multifactorial - opioid-related sedation, language and cultural barrier, and unfamiliarity with the pathology. Her diagnosis was proven 18 hours after the completion of surgery with a plain X-ray. A manual closed reduction was performed with minimal sedation by oral surgery. Conclusion We provided an in-depth discussion of temporomandibular joint dislocation and suggest a simple test that would prevent delayed diagnosis of temporomandibular joint dislocation in any patient undergoing general anesthesia. A normal mandibular excursion should be tested in every patient after surgery in the postoperative care unit, by asking the patient to open and close their mouth during the immediate postoperative recovery period or passively performing the range of motion test. PMID:24139071

  20. Dislocated shoulder - aftercare

    MedlinePlus

    ... aftercare; Shoulder subluxation - aftercare; Shoulder reduction - aftercare; Glenohumeral joint dislocation ... that connect bone to bone) of the shoulder joint. All of these tissues help keep your arm ...

  1. Divergent elbow dislocation with radial shaft fracture, distal ulnar deformation, and distal radioulnar joint instability: an unclassifiable Monteggia variant.

    PubMed

    Laratta, Joseph L; Yoon, Richard S; Frank, Matthew A; Koury, Kenneth; Donegan, Derek J; Liporace, Frank A

    2014-03-01

    Originally described by Monteggia and later classified by Bado, elbow dislocations with concurrent radial and ulnar shaft fractures with distal radioulnar joint (DRUJ) disruption are considered operative cases with high-energy injurious etiologies. Here, we present an unclassifiable Monteggia variant fracture suffered through a high axial load mechanism in a 47-year-old female. The fracture pattern initially exhibited included a divergent elbow dislocation, a radial shaft fracture, plastic deformation of the distal ulna, and DRUJ instability. Here we describe the pattern in detail, along with definitive treatment and clinical outcome at 1 year follow-up.

  2. Nerve Palsy after Total Hip Arthroplasty without Subtrochanteric Femoral Shortening Osteotomy for a Completely Dislocated Hip Joint

    PubMed Central

    Sonohata, Motoki; Kitajima, Masaru; Kawano, Shunsuke; Mawatari, Masaaki

    2016-01-01

    Background: Neurological injuries are a rare but devastating complication after total hip arthroplasty (THA). The purpose of this study was to retrospectively determine the frequency of nerve palsy after THA without subtrochanteric femoral shortening osteotomy in patients with a completely dislocated hip joint without pseudo-articulation between the femoral head and iliac bone. Methods: Between October 1999 and September 2001, nine primary THAs were performed for patients with a completely dislocated hip joint. The limb lengths, neurological abnormalities, and the extent of their neurological recovery were evaluated. Three THAs were combined with subtrochanteric femoral shortening osteotomy, and six THAs were combined without subtrochanteric femoral shortening osteotomy. Results: The mean length of the operation was 4.8 cm (range, 3.0-6.5 cm). Sciatic nerve palsy developed in four of the nine patients after THA. None of the cases with sciatic nerve palsy were combined with subtrochanteric femoral shortening osteotomy. Three of four patients did not completely recover from sciatic nerve palsy. Conclusions: THA for patients with a completely dislocated hip was associated with a high risk of nerve palsy due to excessive limb lengthening; the potential for recovery from nerve palsy was observed to be poor. Subtrochanteric femoral shortening osteotomy should be used in combination with THA in patients with a completely dislocated hip. PMID:28217204

  3. Percutaneous Screw Fixation of Crescent Fracture-Dislocation of the Sacroiliac Joint.

    PubMed

    Shui, Xiaolong; Ying, Xiaozhou; Mao, Chuanwan; Feng, Yongzeng; Chen, Linwei; Kong, Jianzhong; Guo, Xiaoshan; Wang, Gang

    2015-11-01

    Crescent fracture-dislocation of the sacroiliac joint (CFDSIJ) is a type of lateral compression pelvic injury associated with instability. Open reduction and internal fixation is a traditional treatment of CFDSIJ. However, a minimally invasive method has never been reported. The purpose of this study was to assess the outcome of closed reduction and percutaneous fixation for different types of CFDSIJ and present their clinical outcome. The authors reviewed 117 patients diagnosed with CFDSIJ between July 2003 and July 2013. Closed reduction and percutaneous fixation was performed in 73 patients. Treatment selection was based on Day's fracture classification. For type I fractures, fixation perpendicular to the fracture line were performed. For type II fractures, crossed fixation was performed. For type III fractures, fixation was performed with iliosacral screws. Forty-four patients were treated by open reduction and plate fixation. Demographics, fracture pattern distribution, blood loss, incision lengths, revision surgeries, radiological results, and functional scores were compared. All 117 patients were followed for more than 6 months (mean, 14 months [range, 6-24 months]). Blood loss, extensive exposure, duration of posterior ring surgery, duration of hospital stay, and infection rates were lower in the closed group (P<.01). Patients in the closed group achieved better functional performance (P<.01). There were no significant differences in reduction quality (P=.32), revision surgery rates (P=.27), and iatrogenic neurologic injuries (P=.2) between the 2 groups. The authors' results indicate that closed reduction and percutaneous fixation is a safe and effective surgical method for CFDSIJ.

  4. Fracture dislocation of the sacro-coccygeal joint in a 12-year-old boy. A case report and literature review.

    PubMed

    Hamoud, K; Abbas, J

    2015-11-01

    A case report and literature review. To present a rare case of facture dislocation of the sacro-coccygeal joint in a 12-year-old boy who was treated conservatively. Fracture dislocations of the sacrum or the sacro-coccygeal joint are infrequent injuries and are rarely reported. The treatment for these disorders is usually conservative. Detailed description of the anterior dislocation (Salter-Harris type I) of the sacro-coccygeal joint in this child and its management are presented, with review of the relevant literature. A conservative treatment was performed, with excellent clinical and radiological result at three years after the injury. MR imaging obtained at two years showed very good healing and alignment. Fracture dislocation of the sacro-coccygeal joint in the pediatric population should be treated conservatively, as the potential of healing and remodeling is great. Closed reduction should not be attempted.

  5. The biomechanical study of the influence to the forefoot plantar pressure of the first tarsometatarsal joint fracture-dislocation fixed by three different implants

    PubMed Central

    Yu, Xiao; Pang, Qing-jiang; Chen, Xian-jun

    2017-01-01

    Objectives: To study the influence of forefoot plantar pressure of the first tarsometatarsal joint fracture-dislocation by three different implants to provide experimental reference in selecting implants. Methods: Eight fresh foot specimens were made into the models of the first tarsometatarsal joint fracture-dislocation, which were fixed with 3.5 mm cortical screw, 1/4 tubular plate and compressive staple in turn. After the loading of 600N, the changes of the plantar pressure in forefoot were measured by the method of the F-scan plantar pressure system. Results: After first tarsometatarsal joint fracture-dislocation, the peak pressure under the first metatarsal head would decrease, while the pressure under the second metatarsal head would increase(P<0.05). When the first tarsometatarsal joint was fixed with screw or plate respectively; the peak pressure under the two metatarsal heads would tend to be normal. However, the staple fixation would show the statistical significant difference, although the peak pressure under the first and second metatarsal heads were recovered in some extent(P<0.05). Conclusions: After the first tarsometatarsal joint fracture-dislocation, the plantar pressure might be compensated partly by the adjacent metatarsal heads. While the first tarsometatarsal joint fracture-dislocation was fixed by screw or plate, the plantar pressure of the forefoot would return to the normal state. However, if the joint was fixed by the staple, it would still be difficult to return the plantar pressure to be normal. PMID:28367189

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

    PubMed Central

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

    2016-01-01

    Background: 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. Methods: 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 Results: 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. Conclusion: 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. PMID:27847854

  7. [Three cases of chronic volar dislocation of the distal radioulnar joint that were treated with the Sauvé-Kapandji procedure].

    PubMed

    Saito, Jun; Sakai, Akinori; Okimoto, Nobukazu; Ohshige, Toshihisa; Murakami, Taizou; Nakamura, Toshitaka

    2003-06-01

    Three cases of chronic volar dislocation of the distal radioulnar joint were treated with the Sauvé-Kapandji procedure. All patients were in their twenties. They visited our clinic complaining limitation of forearm wrist rotation and pain around the wrist for more than 6 weeks after an injury. Radiograph and CT scan revealed chronic volar dislocation of the distal radioulnar joint. Closed reduction failed. The Sauvé-Kapandji procedure was required to prevent the distal radioulnar joint from becoming unstable after open reduction. Range of motion of the injured wrist improved greatly, pain disappeared and they were able to return to sports after the operation and rehabilitation. Therefore, the Sauvé-Kapandji procedure is effective in curing chronic volar dislocation of the distal radioulnar joint.

  8. 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

  9. Successful closed manipulation of a pure lateral traumatic dislocation of the elbow joint using a modified Stimson's technique: a case report

    PubMed Central

    Khan, Sameer K; Chopra, Rajat; Chakravarty, Debasis

    2008-01-01

    Introduction Pure lateral elbow dislocation is rare, and a successful closed reduction is even rarer. Reduction can be hindered by swelling, soft tissue interposition or associated fractures. Case presentation We present a pure lateral traumatic dislocation of the elbow joint in a 40-year-old man. This was successfully manipulated and reduced in casualty using a modification of the gravity-aided 'hanging arm' technique originally described for shoulder dislocations by Stimson. Conclusion We strongly recommend the use of this simple technique in these rare yet difficult injuries, in order to avoid potential complications with general anaesthesia and surgery. PMID:18498622

  10. THE EFFECTIVENESS OF PHYSICAL FACTORS IN THE TREATMENT OF COMPRESSION-DISLOCATION DYSFUNCTION OF THE TEMPOROMANDIBULAR JOINT.

    PubMed

    Rybalov, O; Yatsenko, P; Moskalenko, P; Yatsenko, O; Lakhtin, Yu

    2016-02-01

    The aim of the study was clinical and functional assessment of the effectiveness of physical factors in the treatment of patients with compression-dislocation dysfunction of the temporomandibular joint. We observed two groups of patients. All patients were undergone the repositioning of the joint heads of the lower jaw. Patients of the index group were assigned a vibrating massage of all masseter muscles, tourmaline ceramic on the joint area and a local physical therapy. Patients in the control group had only lidocaine blockade of periarticular area twice a week. Treatment efficacy was evaluated on the eighth day after the start of the treatment according to the bioelectric activity of the genuine masseter and temporal muscles, the intensity of pain according to in Visual Analog Scale, and according to the results of the clinical examination. In most patients of the index group the electromyography data after treatment were approaching to norm, the phenomenon of dysfunction of the temporomandibular joints was reversed. In the control group the full restoration of the functional activity of muscle did not occur. The addition to the complex of therapeutic measures a vibration massage, tourmaline ceramics and local physical therapy for patients with dysfunction of the temporomandibular joints allows to get a positive effect.

  11. [An inveterate fracture of the barton type of the distal radius with dislocation in the radiocarpal joint--case history].

    PubMed

    Bednarenko, Marcin; Kotela, Ireneusz; Bołtuć, Witold; Jakubowski, Lukasz

    2006-01-01

    Barton's fracture was first described and isolated as a disease entity in 1839. It is a quite rare fracture constituting, according to various authors 1.5-2.3% of the distal radius fractures. It is usually accompanied with subluxation or luxation in the radiocarpal joint. In the study we present treatment, dealing with operative difficulties and rehabilitation in a 52-year-old patient with an inveterate fracture of the Barton type of the distal radius with dislocation in the radiocarpal joint. He was previously treated by a local quack. The patient underwent an operative treatment; fragments were anatomically repositioned and a stable fixation was applied. As a result of treatment and intensive rehabilitation, we achieved synostosis and functionality of the wrist and left hand.

  12. THA following deformities due to congenital dislocation of the hip joint.

    PubMed

    Macheras, George A; Koutsostathis, Stefanos D; Lepetsos, Panagiotis; Anastasopoulos, Panagiotis P; Galanakos, Spyridon; Papadakis, Stamatios A

    2014-10-02

    Total hip replacement is the treatment of choice for the patient suffering from end-stage hip osteoarthritis. Excellent long-term results have been published. In the presence of deformities due to congenital hip dislocation, total hip replacement is, in most of the cases, a difficult task, since the technique of performing such an operation is demanding and the results could vary. This paper presents our experience and preferred strategies focusing on challenges and surgical techniques associated with reconstructing the dysplastic hip.

  13. 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.

  14. Irreducible posterolateral elbow dislocation.

    PubMed

    Atkinson, Cameron T; Pappas, Nick D; Lee, Donald H

    2014-02-01

    Elbow dislocations are a high-energy traumatic event resulting in loss of congruence of a stable joint. The majority of elbow dislocations can be reduced by closed means and treated conservatively. We present a case of an irreducible elbow dislocation with reduction blocked by the radial head buttonholed through the lateral ligamentous complex. We performed open reduction with release followed by repair of the lateral ligamentous complex. Clinicians need to understand this unique variant of an elbow dislocation to appropriately treat this operative injury.

  15. The Sauvé-Kapandji procedure for chronic dislocation of the distal radio-ulnar joint with destruction of the articular surface.

    PubMed

    Nakamura, R; Tsunoda, K; Watanabe, K; Horii, E; Miura, T

    1992-04-01

    The Sauvé-Kapandji procedure has been performed in 15 non-rheumatoid patients with chronic distal radio-ulnar joint dislocation accompanied by joint damage or deformity. The clinical results were favourable; wrist pain improved in all patients, wrist flexion-extension was increased by more than 10 degrees in nine patients, grip strength of at least 80% of the contralateral wrist was achieved in 11 patients, and forearm rotation was more than 150 degrees in 12 patients. However, X-ray examination revealed an unstable proximal ulnar stump and radio-ulnar convergence in all patients similar to that associated with the Darrach procedure. Although the Sauvé-Kapandji procedure can preserve ulnar support of the wrist and is believed to yield more satisfactory results than the Darrach procedure, its extensive use is not recommended for non-rheumatoid distal radio-ulnar joint disorders, but it is recommended for chronic distal radio-ulnar joint dislocation with articular injury or deformity.

  16. [Elbow dislocation].

    PubMed

    de Pablo Márquez, B; Castillón Bernal, P; Bernaus Johnson, M C; Ibañez Aparicio, N M

    2017-03-09

    Elbow dislocation is the most frequent dislocation in the upper limb after shoulder dislocation. Closed reduction is feasible in outpatient care when there is no associated fracture. A review is presented of the different reduction procedures.

  17. Posterior talar fracture with dislocation of both talo-navicular and subtalar joints: a variant type II of the Sneppens classification

    PubMed Central

    Galanopoulos, Ilias; Fogg, Quentin; Ashwood, Neil

    2012-01-01

    A 63-year-old man fell from a ladder, thus causing an axial compression injury to the right ankle. Severe deformity was evident and the ankle could not be reduced by simple manipulation. The skin was tented and appearing critically contused. Radiographs revealed an oblique fracture of the posterior aspect of the talar body with dislocation of both the talo-navicular and subtalar joints, an injury previously not described in the literature. The fracture–dislocation was anatomically reduced within 3 h of presentation and stability achieved with two headless buried compression screws. CT scan confirmed anatomical reduction and the patient remained non-weight bearing in a cast for 6 weeks. One year postoperatively, the patient remains pain-free with no radiological signs of avascular necrosis of the talus. This injury is unique and despite its severity and soft tissue compromise good quality reduction and internal fixation resulted in an excellent clinical outcome. PMID:22847568

  18. Treatment of chronic recurrent dislocation of the temporomandibular joint with injection of autologous blood alone, intermaxillary fixation alone, or both together: a prospective, randomised, controlled clinical trial.

    PubMed

    Hegab, Ayman F

    2013-12-01

    Our aim was to evaluate the efficacy of autologous blood injection in the treatment of chronic recurrent dislocation of the temporomandibular joint (TMJ) in a prospective randomised controlled clinical study. Forty-eight patients (11 men and 37 women) with chronic recurrent dislocation of the TMJ were randomly assigned to 1 of 3 equally sized groups. Patients in the first group were treated with injection of autologous blood (ABI) alone into the superior joint space and the pericapsular tissues. Those in the second group were treated with intramaxillary fixation (IMF) alone for 4 weeks, and those in the third group were treated with ABI and IMF for 4 weeks. Interincisal distance, digital panoramic radiograph, incidence of recurrent dislocation, and pain in the TMJ were assessed postoperatively at 2 weeks and at 1, 3, 6, and 12 months. The mean (SD) reduction in interincisal distance in the group treated with both techniques was 11.0 (1.9), which was significantly higher than in either the group treated with ABI, which was 8.5 (2.4) or IMF, which was 9.1 (2.1). The results in the ABI group and the IMF group did not differ significantly. The combined group showed the biggest decrease. The ABI alone group had the most recurrences (n=8, which were treated by repeated injections with no recurrence after the third). The IMF alone group had only 3 and there were none in the combined group. We conclude that ABI is a simple and safe technique for the treatment of dislocation of the TMJ in the outpatient clinic. Recurrence can be overcome by multiple injections. However, the best clinical results are given by a combination of ABI and IMF.

  19. The prevalence of chondrocalcinosis (CC) of the acromioclavicular (AC) joint on chest radiographs and correlation with calcium pyrophosphate dihydrate (CPPD) crystal deposition disease.

    PubMed

    Parperis, Konstantinos; Carrera, Guillermo; Baynes, Keith; Mautz, Alan; Dubois, Melissa; Cerniglia, Ross; Ryan, Lawrence M

    2013-09-01

    Digital imaging combined with picture archiving and communication system (PACS) access allows detailed image retrieval and magnification. Calcium pyrophosphate dihydrate (CPPD) crystals preferentially deposit in fibrocartilages, the cartilage of the acromioclavicular (AC) joint being one such structure. We sought to determine if examination of the AC joints on magnified PACS imaging of chest films would be useful in identifying chondrocalcinosis (CC). Retrospective radiographic readings and chart reviews involving 1,920 patients aged 50 or more who had routine outpatient chest radiographs over a 4-month period were performed. Knee radiographs were available for comparison in 489 patients. Medical records were reviewed to abstract demographics, chest film reports, and diagnoses. AC joint CC was identified in 1.1 % (21/1,920) of consecutive chest films. Patients with AC joint CC were 75 years of age versus 65.4 in those without CC (p < 0.0002). Four hundred eighty-nine patients had knee films. Six of these patients had AC joint CC, and of these, five also had knee CC (83 %). Of the 483 without AC joint CC, 62 (12 %) had knee CC (p = 0.002). Patients with AC joint CC were more likely to have a recorded history of CPPD crystal deposition disease than those without AC joint CC (14 versus 1 %, p = 0.0017). The prevalence of AC joint CC increases with age and is associated with knee CC. A finding of AC joint CC should heighten suspicion of pseudogout or secondary osteoarthritis in appropriate clinical settings and, in a young patient, should alert the clinician to the possibility of an associated metabolic condition.

  20. Dorsal fracture-dislocation of the proximal interphalangeal joint: a comparative study of percutaneous Kirschner wire fixation versus open reduction and internal fixation.

    PubMed

    Aladin, A; Davis, T R C

    2005-05-01

    Nineteen patients with a dorsal fracture-dislocation of the proximal interphalangeal joint of a finger were treated with either closed reduction and transarticular Kirschner wire fixation (eight cases) or open reduction and internal fixation, using either one or two lag screws (six cases) or a cerclage wire (five cases). At a mean follow-up of 7 (range 6-9) years, most patients reported satisfactory finger function, even though some of the injuries healed with proximal interphalangeal joint incongruency (seven cases) or subluxation (four cases). Those treated by open reduction complained of more "loss of feeling" in the affected finger and those specifically treated by cerclage wire fixation reported more cold intolerance and had a significantly larger fixed flexion deformity (median, 30 degrees : range 18-38 degrees ) and a smaller arc of motion (median, 48 degrees : range 45-60 degrees ) at the proximal interphalangeal joint, despite having the best radiological outcomes. Closed reduction and transarticular Kirschner wire fixation produced satisfactory results, with none of the eight patients experiencing significant persistent symptoms despite a reduced arc of proximal interphalangeal joint flexion (median=75 degrees ; range 60-108 degrees ). The results of this relatively simple treatment appear at least as satisfactory as those obtained by the two techniques of open reduction and internal fixation, both of which were technically demanding.

  1. Unusual combination of lesions of the traumatic hand: closed central slip laceration of the extensor and interphalangeal thumb joint's dislocation (a case report).

    PubMed

    Boussakri, Hassan; Azarkane, Mohamad; Dahmani, Omar; Elidrissi, Mohamad; Shimi, Mohamed; Elibrahimi, Abdelhalim; Elmrini, Abdelmajid

    2014-01-01

    From the functional standpoint, the hand is one of the most important organs of the body. However, its significance depends largely upon the pincer action of the thumb-index. The management of traumatic lesions of the hand is nowadays' subject of numerous scientific discussions. We present here the case of a patient with a recent laceration of the central slip of the extensor tendon with boutonniere deformity linked to a dislocated interphalangeal thumb of the same hand with a loss of force of the clip thumb and index finger. This combination is a rare lesional of the traumatic hand that has not been previously reported in any orthopedic literature. It was observed after adopting the orthopedic treatment that the range of motion of its joint was at the same level as its healthy side without observing any redislocations during the 6-month follow-up period.

  2. Developmental Dislocation (Dysplasia) of the Hip (DDH)

    MedlinePlus

    ... developmental dysplasia (dislocation) of the hip (DDH), the hip joint has not formed normally. The ball is loose ... be taken to provide detailed pictures of the hip joint. Treatment When DDH is detected at birth, it ...

  3. Pediatric complex divergent elbow dislocation.

    PubMed

    van Wagenberg, Jan-Maarten F; van Huijstee, Pieter J; Verhofstad, Michiel H J

    2011-01-01

    A divergent dislocation of the elbow is a very rare injury, and only a few cases have been described in the literature. It is characterized as a dorsal dislocation of the ulnohumeral joint combined with a lateral dislocation of the proximal radius. All three articulations of the elbow joint are involved. Like in our case, it can be accompanied by an avulsion fracture of the coronoid and a distal radius fracture. For correct understanding of the injury, proper radiographic studies are imperative. In contrast to some earlier reports that advise a conservative approach, we performed a very aggressive operative treatment. To ensure anatomic reconstruction of the elbow, surgical exposure of the various injuries was performed first. After gross reduction of the joint dislocation, definitive osteosynthesis of the distal radius fracture was performed. Subsequently, the coronoid process and lateral collateral ligament could be repaired anatomically, improving the stability of the elbow. An uneventful recovery with excellent elbow motion and stability was achieved.

  4. Revisiting the differences between irreducible and reducible atlantoaxial dislocation in the era of direct posterior approach and C1-2 joint manipulation.

    PubMed

    Deepak, Arsikere N; Salunke, Pravin; Sahoo, Sushanta K; Prasad, Prashant K; Khandelwal, Niranjan K

    2017-03-01

    OBJECTIVE The current management of atlantoaxial dislocation (AAD) focuses on the C1-2 joints, commonly approached through a posterior route. The distinction between reducible AAD (RAAD) and irreducible AAD (IrAAD) seems to be less important in modern times. The roles of preoperative traction and dynamic radiographs are questionable. This study evaluated whether differentiating between the 2 groups is important in today's era. METHODS Ninety-six consecutive patients with congenital AAD (33 RAAD and 63 IrAAD), who underwent surgery through a posterior approach alone, were studied. The preoperative and follow-up clinical statuses for both groups were studied and compared using Japanese Orthopaedic Association (JOA) scores. The radiological findings of the 2 groups were compared, and the intraoperative challenges described. RESULTS A poor preoperative JOA score (clinical status) was seen in one-fifth of patients with IrAAD, although the mean JOA score was nearly similar in the RAAD and IrAAD groups. There was significant improvement in follow-up JOA score in both groups. However, segmentation defects (such as an assimilated arch of the atlas and C2-3 fusion) and anomalous vertebral arteries were found significantly more often in cases of IrAAD compared with those of RAAD. Os odontoideum was commonly seen in the RAAD group. The C1-2 joints were acute in IrAAD compared with RAAD. Preoperative traction in IrAAD resulted in vertical distraction and improvement in clinical and respiratory status. Surgery for IrAAD required much more drilling and manipulation of the C1-2 joints while safeguarding the anomalous vertebral artery. CONCLUSIONS Bony and vascular anomalies were much more common in patients with IrAAD, which made surgery more challenging than it was in RAAD despite similar approaches. An irreducible dislocation seen on preoperative radiographs made surgeons aware of difficulties that were likely to be encountered and helped them to better plan the surgery

  5. Regular structures in 5CB liquid crystals under the joint action of ac and dc voltages

    NASA Astrophysics Data System (ADS)

    Aguirre, Luis E.; Anoardo, Esteban; Éber, Nándor; Buka, Ágnes

    2012-04-01

    A nematic liquid crystal with high, positive dielectric anisotropy (5CB) has been studied under the influence of the combined action of a dc and an ac electric field. Broad frequency, voltage, and cell thickness ranges were considered. Pattern morphologies were identified; the thresholds and critical wave numbers were measured and analyzed as a function of frequency, dc-to-ac voltage ratio, and thickness. The current-voltage characteristics were simultaneously detected.

  6. Superolateral dislocation of the condyle: report of a rare case.

    PubMed

    Papadopoulos, H; Edwards, R S

    2010-05-01

    Anterior dislocation of the mandibular condyle is commonly seen in patients with chronic dislocation of their temporomandibular joints. Posterior, superior and lateral dislocation is rare. Superolateral dislocation of an intact condyle, let alone intact mandible is uncommon, usually occurring after a traumatic insult to the mandible. The authors report on such a case, and its management.

  7. Hemi-hamate arthroplasty versus transarticular Kirschner wire fixation for unstable dorsal fracture-dislocation of the proximal interphalangeal joint in the hand.

    PubMed

    Barksfield, R C; Bowden, B; Chojnowski, A J

    2015-01-01

    Following the introduction of the hemi-hamate arthroplasty (HHA) technique to our unit, we sought to evaluate the early clinical outcomes achieved with this method of fixation and compare these with simple trans-articular Kirschner wire (K-wire) fixation for dorsal fracture dislocations (DFD) of the proximal interphalangeal joint (PIPJ). Ninteen patients underwent fixation of these injuries with either K-wire fixation (12/19) or hemi-hamate bone grafting (7/19) between 2005 and 2011. At a mean follow-up of 14 weeks median arc of movement at the PIPJ was 65° (range 31° to 108°) following HHA and 56° (range 9° to 85°) (p = 0.82) following temporary transarticular K-wire fixation. Median fixed flexion deformity (FFD) was 20° and 15° for hemi-hamate bone grafting and K-wire fixation respectively. Based upon our findings, transarticular K-wire fixation produced equivalent outcomes to HHA for unstable DFD of the PIPJ in the hand.

  8. 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

  9. [Spasm of the adductor muscles, pre-dislocation and dislocations of the hip joints in children and adolescents with cerebral palsy. Clinical observations on aetiology, pathogenesis, therapy and rehabilitation. Part I: The effect of open myotenotomy of the gracilis muscle and of the long and short adductor muscles in connection with total extrapelvine resection of the obturator nerve, on the hip joints and static function (author's transl)].

    PubMed

    Fettweis, E

    1979-02-01

    Spasm and contraction of the adductor muscles involve, on the one hand, danger in respect of the development of a dislocation of the hip, and are a serious impediment to a walking ability on the other. Hence, surgery is often necessary. The article reports on the results of consequent weakening of the adductor muscles as a result of open myotenotomy in association with complete extrapelvine resection of the obturator nerve. 27 patients were subjected to surgery--in most cases bilaterally--at an age between 2 years and 5 months and 18 years, with a follow-up period of up to 15 years. The study does not include patients with spastic dislocation of the hip in whom this method was applied on the non-dislocated side and on the dislocated side in combination with iliopsoas tenotomy. This method makes it possible to achieve regression of existing defective positions of the hip joints. In a few cases, the valgus position of the neck of the femur was corrected to some extent. In two patients it was not possible to prevent the progress of a developing dislocation of the hip. These results show that, whereas the adductor muscles represent an essential factor for the occurrence of a spastic dislocation of the hip, other forces are most probably also involved. In the majority of cases, results were favourable in respect of the static function, although in some cases the success became evident after several years only, especially in mentally retarded patients and in apathetic individuals. Important for therapeutic success is the follow-up. The principles of its therapy are thoroughly discussed. Surgery is indicated only in special cases. Indications must be observed very strictly, since the risk of excessive weakening of the adductor muscles should not be underestimated.

  10. Closed reduction and treatment of 2 volar thumb metacarpophalangeal dislocations: report of 2 cases.

    PubMed

    Beck, John D; Klena, Joel C

    2011-04-01

    Volar dislocation of the metacarpophalangeal joint of the thumb may be irreducible by closed means. We describe 2 patients with volar dislocation of the thumb metacarpophalangeal joint treated with closed reduction and casting.

  11. Simple Elbow Dislocation.

    PubMed

    Armstrong, April

    2015-11-01

    Simple elbow dislocation refers to those elbow dislocations that do not involve an osseous injury. A complex elbow dislocation refers to an elbow that has dislocated with an osseous injury. Most simple elbow dislocations are treated nonoperatively. Understanding the importance of the soft tissue injury following a simple elbow dislocation is a key to being successful with treatment.

  12. Isolated Carpo-Metacarpal Dislocation of the Thumb

    PubMed Central

    Suresh, SS; Zaki, Hosam; Ahmed, Aamir

    2012-01-01

    Introduction: Isolated dislocations of the trapezio metacarpal joint without associated fracture has been reported very rarely in the literature. There are reports of associated injuries like fracture of the trapezium, dislocation of the metacarpophalangeal joint and fractures of the base of the thumb metacarpal. Case Report: Authors report a case of isolated carpometacarpal dislocation of the right thumb, in an adult, successfully managed conservatively. At 15 months follow up the patient had full function of the hand without any clinical or radiological evidence of instability or posttraumatic arthritis. Conclusion: Isolated dislocations can be successfully managed by closed reduction and immobilization in a back slab, with unstable dislocations requiring surgical intervention. PMID:27298846

  13. Congenital knee dislocation in a 49,XXXXY boy.

    PubMed Central

    Sijmons, R H; van Essen, A J; Visser, J D; Iprenburg, M; Nelck, G F; Vos-Bender, M L; de Jong, B

    1995-01-01

    We report on a 12 year old mentally retarded boy who presented at birth with bilateral knee dislocations, dislocation of the right hip, and general joint laxity. Cytogenetic studies showed a 49,XXXXY karyotype. Hyperlaxity of joints is known to occur in 49,XXXXY patients, but congenital knee dislocation has not been reported. Rarely in 49,XXXXY and 49,XXXXX syndromes Larsen-like features may be seen. Patients with congenital joint dislocation or laxity, combined with other malformations, especially if psychomotor development is delayed, should be karyotyped to exclude chromosomal abnormalities. Images PMID:7643364

  14. Dislocated Shoulder

    MedlinePlus

    ... gradual rehabilitation program designed to restore range of motion, strength and stability to your shoulder joint. If ... when the pain improves. Maintain the range of motion of your shoulder. After one or two days, ...

  15. Complete dorsal dislocation of the carpal scaphoid with perilunate dorsal dislocation

    PubMed Central

    Kang, Jong Woo; Park, Jong Hoon; Suh, Dong Hun; Park, Jong Woong

    2016-01-01

    Complete dorsal dislocation of the carpal scaphoid combined with dorsal perilunate dislocation is an extremely rare carpal injury. We describe the case of a 23-year-old man who presented with a complete dorsal dislocation of the carpal scaphoid, combined with a perilunate dislocation. Surgical treatment was performed with open reduction and interosseus ligament repair. At 4 years follow up, the patient's wrist pain had completely resolved without limitations of wrist joint motion and without evidence of avascular necrosis of the carpal scaphoid. PMID:27512229

  16. Lateral subtalar dislocation: Case report and review of the literature

    PubMed Central

    Veltman, Ewout S; Steller, Ernst JA; Wittich, Philippe; Keizer, Jort

    2016-01-01

    A case of complicated lateral subtalar dislocation is presented and the literature concerning this injury is reviewed. Subtalar joint dislocations are rare and often the result of a high-energy trauma. Complications include avascular necrosis of the talus, infection, posttraumatic osteoarthritis requiring arthrodesis and chronic subtalar instability. Negative prognostic factors include lateral and complicated dislocations, total talar extrusions, and associated fractures. A literature search was performed to identify studies describing outcome after lateral subtalar joint dislocation. Eight studies including fifty patients could be included, thirty out of 50 patients suffered a complicated injury. Mean follow-up was fifty-five months. Ankle function was reported as good in all patients with closed lateral subtalar dislocation. Thirteen out of thirty patients with complicated lateral subtalar joint dislocation developed a complication. Avascular necrosis was present in nine patients with complicated injury. Four patients with complicated lateral subtalar dislocation suffered deep infection requiring treatment with antibiotics. In case of uncomplicated lateral subtalar joint dislocation, excellent functional outcome after closed reduction and immobilization can be expected. In case of complicated lateral subtalar joint dislocation immediate reduction, wound debridement and if necessary (external) stabilisation are critical. Up to fifty percent of patients suffering complicated injury are at risk of developing complications such as avascular talar necrosis and infection. PMID:27672576

  17. Subacute dislocation of the elbow following Galeazzi fracture-dislocation of the radius: A case report

    PubMed Central

    2011-01-01

    Introduction The Galeazzi fracture-dislocation was originally described by Sir Astley Cooper in 1822 but was named after Italian surgeon Ricardo Galeazzi in 1934. It is an injury classified as a radial shaft fracture with associated dislocation of the distal radioulnar joint and disruption of the forearm axis joint. The associated distal radioulnar joint injury may be purely ligamentous in nature, tearing the triangular fibrocartilaginous complex, or involve bony tissue (that is, ulnar styloid avulsions) or both. We report this case because of the rare association of posterior dislocation of the elbow along with Galeazzi fracture-dislocation. To the best of our knowledge, this has not been previously reported in the English literature. Case presentation A 26-year-old Caucasian man presented to our department after a fall from a motorbike. He sustained a closed, isolated Galeazzi fracture-dislocation of the right forearm and no associated elbow injuries, and this necessitated open reduction and internal fixation of the radius. Post-operative radiographs films were satisfactory. However, clinical and radiological evidence of ipsilateral elbow dislocation was noted at a five-week follow-up, subsequently requiring open reduction of the joint and collateral ligament repair. Our patient was noted to have full elbow and forearm function at three months. Conclusions Although the Galeazzi fracture-dislocation has been classically described as involving only the distal radioulnar joint, traumatic forces can be transmitted to the elbow via the interosseous membrane of the forearm. This can lead to instability of the elbow joint. Therefore, we recommend that, in every case of forearm fracture, both elbow and wrist joints be assessed clinically as well as radiologically for subluxation or dislocation. PMID:22185342

  18. [Arthrography in congenital hip dislocation].

    PubMed

    Sipukhin, Ia M; Bazlova, E S; Cheberiak, N V

    1992-01-01

    The paper is concerned with the results of contrast arthrography in 73 children with hip joint dysplasia, among which true dislocations prevailed (70 patients). In addition to bone alterations, arthrography revealed various soft tissue changes like hypertrophy and deformity of limbus, soft tissue interposition, separation of the articular sac with the presence of an isthmus, disintegration of articular cartilages. These findings are used to define indications for surgical intervention as well as for planning the area of operation.

  19. Dislocation motion and instability

    NASA Astrophysics Data System (ADS)

    Zhu, Yichao; Chapman, Stephen Jonathan; Acharya, Amit

    2013-08-01

    The Peach-Koehler expression for the stress generated by a single (non-planar) curvilinear dislocation is evaluated to calculate the dislocation self stress. This is combined with a law of motion to give the self-induced motion of a general dislocation curve. A stability analysis of a rectilinear, uniformly translating dislocation is then performed. The dislocation is found to be susceptible to a helical instability, with the maximum growth rate occurring when the dislocation is almost, but not exactly, pure screw. The non-linear evolution of the instability is determined numerically, and implications for slip band formation and non-Schmid behavior in yielding are discussed.

  20. Jaw Dislocation as an Unusual Complication of Upper Endoscopy

    PubMed Central

    Dellon, Evan S.; Steele, David

    2016-01-01

    This case report presents an unusual complication of upper endoscopy, resulting in jaw dislocation. Temporomandibular joint dislocation is commonly reported in association with anesthesia and intubation, but it is not widely recognized as a complication of gastrointestinal endoscopy. This report also reviews the current literature regarding this complication and discusses the potential causes of dislocation, differential diagnoses for jaw pain following endoscopy, and recommendations for prevention. PMID:27403117

  1. Traumatic posterior dislocation of hip in children.

    PubMed

    Kutty, S; Thornes, B; Curtin, W A; Gilmore, M F

    2001-02-01

    Traumatic posterior dislocation of the hip joint in children is an uncommon injury. It constitutes a true orthopedic emergency. It makes up over 80% of pediatric hip dislocations. In children, it can occur as a result of minimal trauma, which is attributed to a soft pliable acetabulum and ligamentous laxity. In skeletally mature adolescents, a greater force is required to dislocate the hip joint. Delay in reduction is associated with long-term complications such as avascular necrosis and degenerative arthritis. Avascular necrosis is related to the duration of dislocation. A poorer prognosis is associated with delay in reduction beyond 6 hours, advanced skeletal maturity, or multiple traumas. Prompt reduction minimizes complications. We report two cases of traumatic posterior dislocation of hip in children aged 3 and 14 years. Both were reduced within 6 hours of dislocation, and review at 6 months revealed normal examination and no evidence of any post-traumatic changes. Post-reduction treatment remains without a consensus. This review highlights the clinical presentation, management, and time-sensitive complications of the injury.

  2. Simultaneous shoulder and elbow dislocation.

    PubMed

    Cobanoğlu, Mutlu; Yumrukcal, Feridun; Karataş, Cengiz; Duygun, Fatih

    2014-05-23

    Ipsilateral shoulder and elbow dislocation is very rare and only six articles are present in the literature mentioning this kind of a complex injury. With this presentation we aim to emphasise the importance of assessing the adjacent joints in patients with trauma in order not to miss any accompanying pathologies. We report a case of a 43-year-old female patient with ipsilateral right shoulder and elbow dislocation treated conservatively. The patient reported elbow pain when first admitted to emergency service but she was diagnosed with simultaneous ipsilateral shoulder and elbow injury and treated conservatively. As a more painful pathology may mask the additional ones, one should hasten to help before performing a complete evaluation. Any harm caused to the patient due to this reason would not be a complication but a malpractice.

  3. Simultaneous shoulder and elbow dislocation

    PubMed Central

    Çobanoğlu, Mutlu; Yumrukcal, Feridun; Karataş, Cengiz; Duygun, Fatih

    2014-01-01

    Ipsilateral shoulder and elbow dislocation is very rare and only six articles are present in the literature mentioning this kind of a complex injury. With this presentation we aim to emphasise the importance of assessing the adjacent joints in patients with trauma in order not to miss any accompanying pathologies. We report a case of a 43-year-old female patient with ipsilateral right shoulder and elbow dislocation treated conservatively. The patient reported elbow pain when first admitted to emergency service but she was diagnosed with simultaneous ipsilateral shoulder and elbow injury and treated conservatively. As a more painful pathology may mask the additional ones, one should hasten to help before performing a complete evaluation. Any harm caused to the patient due to this reason would not be a complication but a malpractice. PMID:24859563

  4. Use of cervical collar in temporomandibular dislocation.

    PubMed

    Jaisani, Mehul R; Pradhan, Leeza; Sagtani, Alok

    2015-06-01

    Dislocation of the temporomandibular joint represents 3 % of all reported dislocated joints. In the last 3 decades many cases of TMJ dislocation have been reported with a wide variety of treatment options ranging from non-surgical conservative approaches to open joint procedures. The question remains whether one method is superior to the others. Conservative treatments are still the option in this part of the continent due to financial constraints and as well as due to availability of skilled manpower. A variety of conservative techniques have been described for reducing dislocations, all of which require 10-14 days of immobilization of the jaw post reduction so as to prevent further episodes of dislocation. Immobilization of the jaw can be done in the form of barrel bandage, barton bandage, head chin cap or maxillomandibular fixation using arch bars. We suggest the use of a cervical collar as a form of post reduction immobilization technique to overcome the inherent disadvantages of conventional forms of immobilization techniques.

  5. Incidence of Posttraumatic Shoulder Dislocation in Poland

    PubMed Central

    Szyluk, Karol J.; Jasiński, Andrzej; Mielnik, Michał; Koczy, Bogdan

    2016-01-01

    Background The incidence of shoulder joint dislocation has been estimated at 11–26 per 100 000 population per year. In our opinion, basic epidemiological data need to be continually updated in studies of large populations. To study the incidence of posttraumatic dislocation of the shoulder joint in the Polish population. Material/Methods We retrospectively investigated the entire Polish population between 1 January 2010 and 1 January 2015. To identify the study group, data collected in the electronic database of the National Health Fund were used. The study group was divided into subgroups to detect possible differences in the incidence of shoulder dislocation with regard to age, sex, and season of the year (month) when the dislocation occurred. Results The cumulative size of the study sample was 192.72 million over the 5 years of the study. We identified 51 409 patients with first posttraumatic shoulder dislocation, at a mean age of 50.83 years (SD 21.12), from 0 to 104 years. The incidence of traumatic shoulder dislocations for the entire study group ranged from 24.75/100 000/year (number of posttraumatic shoulder dislocations per 100 000 persons per year) to 29.09/100 000/year, for a mean of 26.69/100 000/year. Conclusions In this study, the overall incidence of first-time posttraumatic shoulder dislocations in the Polish general population was 26.69 per 100 000 persons per year. These results are higher than estimates presented by other authors. It is necessary to study, regularly update, and monitor this problem in the general population. PMID:27777396

  6. [Bilateral elbow dislocation related to Essex-Lopresti injury].

    PubMed

    Romero Pérez, B; Marcos García, A; Medina Henríquez, J A; Muratore Moreno, G

    2012-01-01

    Elbow dislocation is second in frequency, after the shoulder, whereas bilateral dislocation is uncommon, even less than dislocations with concurrent associated fractures. One of the least frequent associations is the Essex-Lopresti injury which consists of a fracture of the radial head affecting the distal radioulnar joint with injury to the interosseous membrane. This is a case of bilateral elbow dislocation, one of the elbows associated with the Essex-Lopresti injury. During treatment, the premature closed reduction prevails, previously making sure the elbow is stable, the premise which will determine the orthopedic or surgical treatment of the injury.

  7. Complicated Congenital Dislocation of the Knee: A Case Report

    PubMed Central

    Madadi, Firooz; Tahririan, Mohammad A.; Karami, Mohsen; Madadi, Firoozeh

    2016-01-01

    Congenital dislocation of the knee (CDK) is a rare disorder. We report the case of a 7-year-old girl with bilateral knee stiffness, marked anterior bowing of both legs, and inability to walk without aid. Radiologic investigation revealed bilateral knee joint dislocation accompanied by severe anterior bowing of both tibia proximally and posterior bowing of both femur distally, demonstrating a complicated congenital knee dislocation. Two-staged open reduction with proximal tibial osteotomy was performed to align the reduced knee joints. The patient was completely independent in her daily activities after surgical correction. PMID:27847857

  8. Recurrent elbow dislocation--an uncommon presentation.

    PubMed

    Sunderamoorthy, D; Smith, A; Woods, D A

    2005-09-01

    A 58 year old female attended our A&E department following a fall in the garden with swelling and bruising of the right arm and the elbow. Anteroposterior and lateral radiographs were interpreted as showing a normal elbow joint. A diagnosis of soft tissue injury to the elbow was made and the patient was discharged with advice. She returned 2 days later, did not have an x ray, and again given advice. Three weeks later she was referred back to A&E by the general practitioner with persistent swelling of the elbow. Further radiographs showed a posterolateral dislocation of the elbow. The elbow was reduced under sedation but was subsequently dislocated at follow up, and was treated by external fixator and transolecranon pin. The fixator was removed at 4 weeks and the elbow was then stable. This case highlights that recurrent elbow dislocations due to significant ligament injuries can present in joint and subsequently dislocate. A high index of suspicion is necessary and appropriate referral to the specialist must be made to avoid the morbidity associated with recurrent dislocation. It also emphasises the need to always assess the patient on his or her own merits despite previously normal investigations.

  9. Discrete dislocations in graphene

    NASA Astrophysics Data System (ADS)

    Ariza, M. P.; Ortiz, M.

    2010-05-01

    In this work, we present an application of the theory of discrete dislocations of Ariza and Ortiz (2005) to the analysis of dislocations in graphene. Specifically, we discuss the specialization of the theory to graphene and its further specialization to the force-constant model of Aizawa et al. (1990). The ability of the discrete-dislocation theory to predict dislocation core structures and energies is critically assessed for periodic arrangements of dislocation dipoles and quadrupoles. We show that, with the aid of the discrete Fourier transform, those problems are amenable to exact solution within the discrete-dislocation theory, which confers the theory a distinct advantage over conventional atomistic models. The discrete dislocations exhibit 5-7 ring core structures that are consistent with observation and result in dislocation energies that fall within the range of prediction of other models. The asymptotic behavior of dilute distributions of dislocations is characterized analytically in terms of a discrete prelogarithmic energy tensor. Explicit expressions for this discrete prelogarithmic energy tensor are provided up to quadratures.

  10. Irreducible anterior dislocation of the elbow without associated fracture.

    PubMed

    Gyawali, Gopal Prasad; Pokharel, Bishnu; Pokharel, Rohit Kumar

    2013-01-01

    Anterior dislocation of the elbow joint is a rare entity and is usually associated with injuries to surrounding bony and soft tissues. Simple dislocation of the joint is managed conservatively. An eight years old girl had traumatic anterior dislocation of the elbow joint with intact distal neurovascular status. X-rays showed no associated bony injury. Close reductions failed. Per operative findings showed no intra-articular fracture and the radial head was button holed into the anterior joint capsule. Reduction was achieved openly and maintained in a posterior slab for four weeks. Active and assisted mobilization started after removal of the slab. At ten month follow-up there was almost full range of movement of the joint.

  11. Open Galeazzi fracture with ipsilateral elbow dislocation.

    PubMed

    Adanır, Oktay; Yüksel, Serdar; Beytemur, Ozan; Güleç, M Akif

    2016-08-01

    Combination of the Galeazzi fracture and dislocation of the elbow joint in same extremity is very rare. In this article, we report a 26-year-old male patient with a posterolateral dislocation of the elbow and ipsilateral volar type Galeazzi fracture. We performed closed reduction for the elbow dislocation during admission to the emergency department. Patient was taken to the operating room in the sixth hour of his application to emergency department and open wound on the ulnovolar region of the wrist was closed primarily after irrigation and debridement. We performed open reduction and internal fixation of the radial fracture with a dynamic compression plate. After fixation, we evaluated the stability of the elbow joint and distal radioulnar joint. Distal radioulnar joint was unstable under fluoroscopic examination and fixed with one 1.8 mm Kirschner wire in a pronated position. Then, elbow joint was stable. One year after surgery, patient had no pain or sings of instability. At the last follow-up, range of motion of the elbow was 10°-135° and forearm pronation and supination were 70°.

  12. Elbow dislocation with complete triceps avulsion.

    PubMed

    Karuppiah, S V; Knox, D

    2014-01-01

    Radio-ulnar Fracture dislocation of the elbow is a high-energy trauma which can be associated with significant ligamentous injury in adults. We report an unusual triad of injury in a patient with avulsion injury of the triceps. This injury can be thought of as a variant of "terrible triad" with dislocation of radio-ulnar joint, radial head fracture, and medial collateral ligament injury with avulsion of the triceps. Elbow has to be stabilized with early repair of the ligaments for a successful outcome.

  13. Elbow Dislocation with Complete Triceps Avulsion

    PubMed Central

    Karuppiah, S. V.; Knox, D.

    2014-01-01

    Radio-ulnar Fracture dislocation of the elbow is a high-energy trauma which can be associated with significant ligamentous injury in adults. We report an unusual triad of injury in a patient with avulsion injury of the triceps. This injury can be thought of as a variant of “terrible triad” with dislocation of radio-ulnar joint, radial head fracture, and medial collateral ligament injury with avulsion of the triceps. Elbow has to be stabilized with early repair of the ligaments for a successful outcome. PMID:24876982

  14. Metallurgy: Starting and stopping dislocations

    NASA Astrophysics Data System (ADS)

    Minor, Andrew M.

    2015-09-01

    A comparison of dislocation dynamics in two hexagonal close-packed metals has revealed that dislocation movement can vary substantially in materials with the same crystal structure, associated with how the dislocations relax when stationary.

  15. Acute traumatic anterior glenohumeral dislocation complicated by axillary nerve damage: a case report

    PubMed Central

    Kazemi, Mohsen

    1998-01-01

    An elite soccer player presented with a classic acute anterior dislocation of the glenohumeral joint complicated by axillary nerve damage. The incidence, mechanism of injury, clinical presentation, conservative treatment and rehabilitation of the anterior glenohumeral joint dislocation and associated axillary nerve damage are discussed in this paper. ImagesFigure 3

  16. Parallel Dislocation Simulator

    SciTech Connect

    2006-10-30

    ParaDiS is software capable of simulating the motion, evolution, and interaction of dislocation networks in single crystals using massively parallel computer architectures. The software is capable of outputting the stress-strain response of a single crystal whose plastic deformation is controlled by the dislocation processes.

  17. Traumatic proximal tibiofibular dislocation.

    PubMed

    Burgos, J; Alvarez-Montero, R; Gonzalez-Herranz, P; Rapariz, J M

    1997-01-01

    Proximal tibiofibular dislocation is an exceptional lesion. Rarer still is its presentation in childhood. We describe the clinical case of a 6-year-old boy, the victim of a road accident. He had a tibiofibular dislocation associated with a metaphyseal fracture of the tibia.

  18. Electromechanical simulations of dislocations

    NASA Astrophysics Data System (ADS)

    Skiba, Oxana; Gracie, Robert; Potapenko, Stanislav

    2013-04-01

    Improving the reliability of micro-electronic devices depends in part on developing a more in-depth understanding of dislocations because dislocations are barriers to charge carriers. To this end, the quasi-static simulation of discrete dislocations dynamics in materials under mechanical and electrical loads is presented. The simulations are based on the extended finite element method, where dislocations are modelled as internal discontinuities. The strong and weak forms of the boundary value problem for the coupled system are presented. The computation of the Peach-Koehler force using the J-integral is discussed. Examples to illustrate the accuracy of the simulations are presented. The motion of the network of the dislocations under different electrical and mechanical loads is simulated. It was shown that even in weak piezoelectric materials the effect of the electric field on plastic behaviour is significant.

  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. Bilateral traumatic hip dislocation associated with sacro-iliac dislocation.

    PubMed

    Galois, L; Meuley, E; Pfeffer, F; Mainard, D; Delagoutte, J P

    We report a rare injury in an 18-year-old woman who sustained posterior bilateral hip dislocation with sacro-iliac dislocation after a high energy motor vehicle accident. She was treated by closed reduction and skeletal traction. Bilateral traumatic hip dislocation is an uncommon occurrence. Rarer still is bilateral traumatic hip dislocation associated with sacro-iliac dislocation because it combines two different mechanisms of trauma. (Hip International 2002; 1: 47-9).

  1. Conservative Treatment of Carpometacarpal Dislocation of the Three Last Fingers

    PubMed Central

    2016-01-01

    Posterior carpometacarpal (CMC) dislocation is a rare condition. Treatment is usually surgical though no strict consensus can be found upon literature review. If diagnosed early and no associated fractures are found, CMC dislocation could benefit from conservative treatment comprising closed reduction and splint immobilisation. We report the case of a 26-year-old man diagnosed with a posterior dislocation of the third, fourth, and fifth CMC joints after a fall of 1.5 meters, treated by external reduction under procedural sedation and immobilisation with a cast for 6 weeks. Evolution was excellent with no relapse observed during follow-up. Our aim is to increase physician awareness of CMC dislocation so that they seek this injury in the emergency department. Unrecognised CMC dislocation can lead to neurovascular injuries as well as chronic instability and early articular degeneration. PMID:27703817

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

    PubMed

    Behr, Ian; Blint, Andy; Trenhaile, Scott

    2013-12-01

    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.

  3. Convergent and divergent dislocation of the pediatric elbow: two case reports and comprehensive review of literature.

    PubMed

    Parikh, Shital N; Lykissas, Marios G; Mehlman, Charles T; Sands, Steven; Herrera-Soto, Jose; Panchal, Anand; Crawford, Alvin H

    2014-03-01

    Convergent and divergent pediatric elbow dislocations are rare injuries. When properly diagnosed and treated without delay, both types of dislocations have a good prognosis. We describe a case of convergent elbow dislocation in a 16-year-old boy. The patient underwent operative intervention and demonstrated full range of motion at the 4-year follow-up. Our second case describes an 11-year-old boy with a divergent elbow dislocation associated with an ipsilateral distal radius fracture and distal radioulnar joint dislocation. The patient showed full range of motion 1 year after closed reduction and casting and had no residual deformities or abnormalties.

  4. 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

  5. Successful Closed Reduction of a Lateral Elbow Dislocation

    PubMed Central

    Fukuzawa, Takuma; Mitsui, Katsuhiro

    2016-01-01

    In this report, we present a case of lateral elbow dislocation treated with closed reduction. Lateral elbow dislocation is rare, and a closed reduction is reported with even less frequency. The reduction can be hindered by swelling and soft tissue interposition, and we describe the use of a nonoperative reduction technique performed under mild sedation with early physiotherapy to avoid joint stiffness. No additional complication was observed, and the normal range of elbow movement and function was obtained by early physiotherapy. PMID:28097029

  6. Successful Closed Reduction of a Lateral Elbow Dislocation.

    PubMed

    Watanabe, Kenya; Fukuzawa, Takuma; Mitsui, Katsuhiro

    2016-01-01

    In this report, we present a case of lateral elbow dislocation treated with closed reduction. Lateral elbow dislocation is rare, and a closed reduction is reported with even less frequency. The reduction can be hindered by swelling and soft tissue interposition, and we describe the use of a nonoperative reduction technique performed under mild sedation with early physiotherapy to avoid joint stiffness. No additional complication was observed, and the normal range of elbow movement and function was obtained by early physiotherapy.

  7. [Elbow dislocation with ipsilateral proximal radial shaft fracture and radial head dislocation].

    PubMed

    Köhn, N; Mendel, T; Ullrich, B W

    2015-11-01

    Elbow dislocation with ipsilateral proximal radial shaft fracture and dislocated radial head is a rarely described injury. In this article we present the case of a 23-year-old man with this injury. After the initial diagnostics, the radial shaft fracture was osteosynthetically fixed, whereby the anatomical positions of all parts of the elbow joint were correctly aligned and the medial collateral ligament was reconstructed. After 4.5 months the radial shaft fracture was healed with nearly complete functional recovery of the upper extremity. Thus, a good outcome can be expected when all aspects of bony and ligamentous injuries are accurately addressed.

  8. Concurrent palmar lunate dislocation and posterior elbow dislocation: a case report.

    PubMed

    Papanna, Madhavan Chikkapapanna; Al-Hadithy, Nawfal; Sarkar, J S

    2011-12-01

    We report a rare case of concurrent palmar lunate dislocation of the left wrist combined with a posterior dislocation of the left elbow joint in a 40-year-old man. He sustained both injuries after falling onto his outstretched left hand. The elbow was reduced by the closed method. The wrist was treated with open reduction with carpal tunnel decompression and fixation with a Kirschner wire through the volar approach. Both the scapholunate and radioscaphocapitate ligaments were also repaired. At month 3, the patient had no pain in his elbow and minimal pain in his wrist on heavy lifting and had resumed his work as a porter.

  9. Delayed treatment of a neonatal type-I Monteggia fracture-dislocation: a case report.

    PubMed

    Smith, William R; Kozin, Scott H; Zlotolow, Dan A

    2017-03-01

    Delayed diagnosis of a Monteggia fracture-dislocation changes a straightforward, treatable injury into a complex problem. Acute neonatal injuries may be missed because of the inability to visualize the unossified skeleton on radiography, interpreted later as 'congenital' dislocations. We report the case of a 14-month-old with a neonatal Monteggia type-I fracture-dislocation secondary to birth trauma, with anterior radial head dislocation and plastic deformation of the ulna. Uniplanar external fixation was used to restore ulnar length and correct angulation, with subsequent radiocapitellar joint closed reduction. Joint congruity was maintained at the 2-year follow-up, with articular remodeling shown on serial arthrogram.

  10. Recurrent TMJ Dislocation Managed with Botulinum Toxin Type A Injections in a Pediatric Patient.

    PubMed

    Stark, Thomas R; Perez, Cristina V; Okeson, Jeffrey P

    2015-01-01

    Chronic recurrent temporomandibular joint (TMJ) dislocation is an uncommon condition that is painful and distressing to patients and uniquely challenging for clinicians. Sustained TMJ dislocation is not amenable to manual reduction alone when the etiology is muscular in nature. The purpose of this report was to describe the case of a child presenting with recurring temporomandibular joint dislocation secondary to muscle hyperactivity of unknown etiology that was managed with injections of botulinum toxin type A into the inferior lateral pterygoid muscles. The use of this peripheral antispasmoic neurotoxin is a reasonable, safe, and conservative, palliative treatment option for pediatric patients suffering from chronic recurring TMJ dislocation.

  11. Sternoclavicular dislocation: case report and surgical technique.

    PubMed

    Terra, Bernardo Barcellos; Rodrigues, Leandro Marano; Pádua, David Victoria Hoffmann; Martins, Marcelo Giovanini; Teixeira, João Carlos de Medeiros; De Nadai, Anderson

    2015-01-01

    Sternoclavicular dislocations account for less than 5% of all dislocations of the scapular belt. Most cases of anterior dislocation of the sternoclavicular joint do not present symptoms. However, some patients may develop chronic anterior instability and remain symptomatic, and surgical treatment is indicated in these cases. There is a scarcity of reports in the literature relating to reconstruction using the long palmar tendon in cases of traumatic anterior instability. Although rare, these injuries deserve rapid diagnosis and efficient treatment in order to avoid future complications. The aim of this report was to report on a case of a motocross competitor who developed chronic traumatic anterior instability of the sternoclavicular joint and underwent surgical reconstruction using the autogenous long palmar tendon. The patient was a 33-year-old man with a history of anterior dislocation of the sternoclavicular subsequent to a fall during a maneuver in a motocross competition. Conservative treatment was instituted initially, consisting of use of a functional sling to treat the symptoms for 3 weeks, along with physiotherapeutic rehabilitation for 3 months. We chose to use a modification of the "figure of eight" technique based on the studies by Spencer and Kuhn. A longitudinal incision of approximately 10 cm was made at the level of the sternoclavicular joint. The graft from the ipsilateral long palmar tendon was passed through the orifices in the form of a modified "figure of eight" and its ends were sutured together. The patient was immobilized using an American sling for 4 weeks. After 6 months of follow-up, the patient no longer presented pain or instability when movement of the sternoclavicular joint was required. Minor discomfort and slight prominence of the sternoclavicular joint continued to be present but did not affect the patient's activities. Thus, the patient was able to return to racing 6 months after the operation. Our study presented a case of

  12. Congenital subtalar dislocation--a case report.

    PubMed

    Saini, Raghav; Dhillon, M S; Gill, S S

    2009-09-01

    Congenital dislocation of the subtalar joint is one of the rarest forms of presentation of a calcaneo-valgus foot. We report the second case of this type published; an 18-month female child aged was seen with calcaneo-valgus deformity of left foot since birth. She was walking over the medial malleolus and medial border of foot. Radiographs and 3D CT scan of the left foot confirmed the diagnosis of a congenital subtalar dislocation. Surgical correction was achieved through a posterolateral incision, and the reduced joint was fixed with a k-wires for 6 weeks; the foot was immobilized in below knee cast for another 6 weeks, and an ankle foot orthosis was used for another 3 years. At 3 years post-surgical follow up, the child has a plantigrade foot with no functional impairment. Follow up radiographs and 3D CT scan confirmed the maintenance of well aligned talo-calcaneal joint. This type of dislocation should be considered in the differential diagnosis of calcaneo-valgus foot; a clear understanding of the pathology, a precise operative reduction, and long-term use of orthosis results in a favourable outcome.

  13. Temporomandibular chronic dislocation: The long-standing condition

    PubMed Central

    Puche-Torres, Miguel; Iglesias-Gimilio, Maria-Eugenia

    2016-01-01

    Background The temporomandibular joint (TMJ) dislocation can be categorised into three groups: acute, habitual or recurrent and long-standing. The long-standing or protracted lower jaw dislocation refers to a condition that persists for more than one month without reduction. There are a great variety of methods for its treatment, from the manual or non-surgical, to surgical ones like the indirect approach (conservative surgical approach) and direct approach (open joint). Additional procedures in unsuccessful cases may include extra-articular orthognathic techniques to correct a malocclusion until joint replacement. Material and Methods We report four new cases with a minimum of 6 weeks dislocation who were seen since 1995 to 2015 in the Maxillofacial Department of the Clínico Hospital (Valencia, Spain), in which the mean age was 57.5 years. Most of them were bilateral and the gender was predominantly female. Additionally, we have reviewed the related literature. Results All of the cases were successfully treated and half of them required open surgery. Conclusions The report confirms the difficulty of the treatment and reaffirms the necessity to bear in mind the wide variety of methods available for the treatment of this pathology. We stress the difficulties associated with managing the treatment and of suggesting new guidelines. The best option still remains not to delay the diagnostic and to select the appropriate initial treatment. Key words:Temporomandibular luxation, TMJ dislocation, protracted dislocation, long-standing dislocation. PMID:27694782

  14. Dislocation climb models from atomistic scheme to dislocation dynamics

    NASA Astrophysics Data System (ADS)

    Niu, Xiaohua; Luo, Tao; Lu, Jianfeng; Xiang, Yang

    2017-02-01

    We develop a mesoscopic dislocation dynamics model for vacancy-assisted dislocation climb by upscalings from a stochastic model on the atomistic scale. Our models incorporate microscopic mechanisms of (i) bulk diffusion of vacancies, (ii) vacancy exchange dynamics between bulk and dislocation core, (iii) vacancy pipe diffusion along the dislocation core, and (iv) vacancy attachment-detachment kinetics at jogs leading to the motion of jogs. Our mesoscopic model consists of the vacancy bulk diffusion equation and a dislocation climb velocity formula. The effects of these microscopic mechanisms are incorporated by a Robin boundary condition near the dislocations for the bulk diffusion equation and a new contribution in the dislocation climb velocity due to vacancy pipe diffusion driven by the stress variation along the dislocation. Our climb formulation is able to quantitatively describe the translation of prismatic loops at low temperatures when the bulk diffusion is negligible. Using this new formulation, we derive analytical formulas for the climb velocity of a straight edge dislocation and a prismatic circular loop. Our dislocation climb formulation can be implemented in dislocation dynamics simulations to incorporate all the above four microscopic mechanisms of dislocation climb.

  15. 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

  16. Supersonic Dislocation Bursts in Silicon

    SciTech Connect

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

    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 evolution 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.

  17. Elbow Dislocations in Contact Sports.

    PubMed

    Morris, Mark S; Ozer, Kagan

    2017-02-01

    Elbow dislocations are more common in athletes than in the general population. Simple elbow dislocations should be managed with early range of motion and early return to sport, even with high-level contact athletes. Patients with instability on examination or with complex elbow dislocations may require surgical intervention. Overall, the outcomes after simple elbow dislocations are excellent and athletes should be able to return to play without significant limitations.

  18. Dislocated Worker Project.

    ERIC Educational Resources Information Center

    1988

    Due to the severe economic decline in the automobile manufacturing industry in southeastern Michigan, a Dislocated Workers Program has been developed through the partnership of the Flint Area Chamber of Commerce, three community colleges, the National Center for Research in Vocational Education, the Michigan State Department of Education, the…

  19. Elbow fractures and dislocations.

    PubMed

    Little, Kevin J

    2014-07-01

    Elbow fractures are common in pediatric patients. Most injuries to the pediatric elbow are stable and require simple immobilization; however, more severe fractures can occur, often requiring operative stabilization and/or close monitoring. This article highlights the common fractures and dislocations about the pediatric elbow and discusses the history, evaluation, and treatment options for specific injuries.

  20. Behavior of dislocations in silicon

    SciTech Connect

    Sumino, Koji

    1995-08-01

    A review is given of dynamic behavior of dislocations in silicon on the basis of works of the author`s group. Topics taken up are generation, motion and multiplication of dislocations as affected by oxygen impurities and immobilization of dislocations due to impurity reaction.

  1. Pathologic dislocation of the shoulder secondary to septic arthritis: a case report

    PubMed Central

    2009-01-01

    Septic arthritis of the shoulder is uncommon in adults, and complete dislocation of the glenohumeral joint following septic arthritis is extremely rare. We report a case of pathologic shoulder dislocation secondary to septic arthritis in an intravenous drug abuser. PMID:20062648

  2. Acromioclavicular Joint Separations

    DTIC Science & Technology

    2013-01-01

    non-surgical measures, high-grade inju- ries frequently warrant surgical intervention to minimize pain and maximize shoulder function. Factors such as...sports [1–3]. While most injuries can be managed non-operatively, high-grade separations may result in per- sistent pain or functional decline and...joint pathology (cross arm adduction and loading of the AC joint) can be helpful to localize shoulder pain to the AC joint. These tests are especial- ly

  3. 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.

  4. Neglected isolated scaphoid dislocation

    PubMed Central

    Baek, Jong-Ryoon; Cho, Seung Hyun; Lee, Yong Seuk; Roh, Young Hak

    2016-01-01

    The authors present a case of isolated scaphoid dislocation in a 40-year-old male that was undiagnosed for 2 months. The patient was treated by open reduction, Kirschner wire fixation, interosseous ligament repair using a suture anchor and Blatt's dorsal capsulodesis. At 6 years followup, his radiographs of wrist showed a normal carpal alignment with a scapholunate gap of 3 mm and no evidence of avascular necrosis (AVN) of the scaphoid. PMID:27904228

  5. Fractures and Dislocations About the Elbow and Their Adverse Sequelae: Contemporary Perspectives.

    PubMed

    Horrigan, Patrick; Braman, Jonathan P; Harrison, Alicia

    2016-01-01

    Fractures and dislocations of the elbow can result in adverse outcomes. The elbow is a unique joint that allows for great mobility but is predisposed to instability, either simple or complex, in traumatic settings. Even simple elbow instability, in which no fracture is present, may be associated with tremendous soft-tissue injury. Surgical treatment is often required for complex instability in which various fractures are present. The treatment goals for fixation of elbow fractures and dislocations include stable fracture fixation, a stable concentrically reduced joint, and early range of motion. Continued pain, stiffness, and instability as well as heterotopic ossification are common sequelae of elbow fractures and dislocations.

  6. Peptide backbone folding induced by the C(alpha)-tetrasubstituted cyclic alpha-amino acids 4-amino-1,2-dithiolane-4-carboxylic acid (Adt) and 1-aminocyclopentane-1-carboxylic acid (Ac5c). A joint computational and experimental study.

    PubMed

    Aschi, Massimiliano; Lucente, Gino; Mazza, Fernando; Mollica, Adriano; Morera, Enrico; Nalli, Marianna; Paglialunga Paradisi, Mario

    2003-06-07

    The conformational study of a new group of synthetic peptides containing 4-amino-1,2-dithiolane-4-carboxylic acid (Adt), a cysteine-related achiral residue, has been carried out through a joint application of computational and experimental methodologies. Molecular Dynamics simulations clearly suggest the tendency of this molecule to adopt a gamma-turn conformation in vacuum and help in analyzing the complex and crucial conformational behaviour of the dithiolane ring which appears to preferentially adopt a C(S)-like structure. Electronic structure calculations carried out in solution using the Density Functional Theory also indicate the preservation of the gamma-like folding in apolar solvents and the helix-like one in more polar solvents. A comparison with the achiral 1-aminocycloalkane-1-carboxylic acid (Ac5c) has been carried out using the same computational tools. NMR and IR data on dipeptide derivatives containing the Adt or Ac5c residue show that in chloroform solution all the models prefer a gamma-turn structure, centered at the cyclic residue, stabilized by an intramolecular H-bond, whereas in a more polar solvent, i.e. dimethyl sulfoxide, this folding is not maintained. The experimental conformational studies, extended to N-Boc protected tripeptides, clearly indicate the remarkable tendency of both the five-membered C(alpha)-tetrasubstituted cyclic amino acids Adt and Ac5c to induce the gamma-turn structure also in models able to adopt the beta-bend conformation.

  7. Surgical treatment for permanent dislocation of the patella in adults.

    PubMed

    Noda, Mitsuaki; Saegusa, Yasuhiro; Kashiwagi, Naoya; Seto, Yoichi

    2011-12-06

    Permanent dislocation of the patella in adults is a rare condition that presents with complete irreducible lateral dislocation of the patella, combined with secondary changes, such as valgus deformity and leg-length discrepancy. Because these secondary changes cannot heal spontaneously after skeletal maturation if left untreated, the patients frequently possess pathology not limited to the knee joint and extending to the whole lower extremity, such as malalignment or leg-length discrepancy, that can develop into osteoarthritis of the knee. However, to our knowledge, few surgeons advocate the significance of correcting the malalignment in treating adult patients. We treated a 34-year-old woman with permanent dislocation of the patella in a 2-stage surgery, consisting of first-stage correction of valgus deformity and limb shortening using a Ilizarov external fixator and second-stage realignment of the dislocated patella over the trochlea. A follow-up examination conducted 3 years after the second operation revealed plantigrade gait with normal alignment of the lower extremity without limping and medial thrust. The patella was tracking centrally in the patellofemoral groove. Radiographs showed a neutral mechanical axis of the lower extremity, no evidence of patellar subluxation, and no deteriorating osteoarthritic changes at the tibiofemoral joint. This case highlights the importance of correcting secondary changes, such as valgus deformity and leg-length discrepancy, to reduce the risk of future osteoarthrosis and postoperative dislocation, especially when these deformities are substantial.

  8. [Elbow dislocation in childhood. Long-term observational study].

    PubMed

    Frongia, G; Günther, P; Romero, P; Kessler, M; Holland-Cunz, S

    2012-02-01

    Traumatic dislocation of the elbow is rare in children with an incidence of 3-6% of all elbow injuries. In the literature the outcome after elbow dislocation in childhood is rarely discussed. In the present study 33 children treated in our clinic from 2001 to 2008 with an acute traumatic dislocation of the elbow were retrospectively included. All events were unilateral whereby 1 child (3%) showed a recurrence of elbow dislocation after 9 weeks, 30% had a pure dislocation, 70% had a concomitant fracture, 55% showed a fracture of the medial epicondyle, 6% a fracture of the lateral epicondyle and 9% a further fracture. Of the fractures 83% required open reduction with osteosynthesis. After an average of 4.5 years 20 children (61%) were clinically examined. There were no instabilities of the joint and only minor clinical limitations of the range of motion. The established Mayo elbow performance score showed good to excellent results for all children. Despite severe joint trauma with frequently accompanying fractures, post-traumatic functional deficits are rarely limiting, independent of the accompanying fracture. The frequency of recurrence is low and instabilities were not seen.

  9. Inferior hip dislocation after falling from height: A case report

    PubMed Central

    Tekin, Ali Çağrı; Çabuk, Haluk; Büyükkurt, Cem Dinçay; Dedeoğlu, Süleyman Semih; İmren, Yunus; Gürbüz, Hakan

    2016-01-01

    Introduction Traumatic inferior hip dislocation is the least common of all hip dislocations. Adult inferior hip dislocations usually occur after high-energy trauma, very few cases are reported without fracture. Presentation of case A 26-year-old female was brought to the emergency department with severe pain in the left hip, impaired posture and restricted movement following a fall from 15 m height. The hip joint was fixed in 90° flexion, 15° abduction, and 20° external rotation. No neurovascular impairment was determined. On radiologic examination, a left ischial type inferior hip dislocation was detected. Hemorrhagic shock which developed due to acute blood loss to thoracic and abdominal cavity and patient died at third hour after she was brought to the hospital. Discussion Traumatic hip dislocations have high morbidity and mortality rates due to multiple organ damage, primarily of the extremities, chest and abdomen. In the treatment of traumatic hip dislocation, closed reduction is recommended through muscle relaxation under general anesthesia or sedation. This procedure should be applied before any intervention for concomitant extremity injuries. A detailed evaluation on emergency presentation, a multi-disciplinary approach and early diagnosis with the rapid application of imaging methods could be life-saving for such patients. PMID:27058153

  10. [Congenital knee dislocation: case report].

    PubMed

    Arvinius, C; Luque, R; Díaz-Ceacero, C; Marco, F

    2016-01-01

    Congenital knee dislocation is an infrequent condition with unknown etiology. In some cases it occurs as an isolated condition, while in others it coexists with associated conditions or syndromes. The treatment of congenital knee dislocation is driven by the severity and flexibility of the deformity. The literature includes from serial casting or the Pavlik harness to quadriceps tendon plasty or femoral osteotomies. We report herein the case of a congenital dislocation treated with serial casting with a good outcome.

  11. Dislocation Diffusion in Metallic Materials

    DTIC Science & Technology

    2011-09-08

    DATES COVERED (From - To) April 1,2007-March 31, 2010 4. TITLE AND SUBTITLE Dislocation Diffusion in Metallic Materials 5a. CONTRACT NUMBER...SUPPLEMENTARY NOTES 14. ABSTRACT The goals of this project were: (1) perform a fundamental study of atomic diffusion along dislocation cores in metals and...alloys, (2) develop new methods for the calculation of dislocation diffusion coefficients as functions of temperature and chemical composition and (3

  12. Treatment of Chopart Fracture-Dislocations.

    PubMed

    Klaue, Kaj

    2010-06-01

    The Chopart articular space was used by François Chopart (1743-1795) as a practical space for amputation in cases of distal foot tumor. It corresponds to the center of the foot and allows for essential articulation by means of the talo-calcaneo-navicular joint (coxa pedis). Chopart fracture-dislocations may therefore include fractures of the navicular, the cuboid, the talus, and calcaneus. The treatment priorities should therefore include addressing all of the injured soft tissues by immediate joint reduction or restoring bony alignment, including the avoidance of threatening compartment syndromes. Subsequent anatomical bone and joint reconstruction, if possible, should first address the talar head and the navicular. The anterior process of the calcaneus and the cuboid should be aligned to preserve foot alignment in the sagittal and horizontal planes. In severe joint destructions, isolated fusion of the calcaneo-cuboidal joint may help preserve functional mobility of the foot. Isolated or associated talo-navicular fusion considerably limits functional mobility of the foot.

  13. Misfit dislocations in epitaxy

    NASA Astrophysics Data System (ADS)

    van der Merwe, Jan H.

    2002-08-01

    This article on epitaxy highlights the following: the definition and some historical milestones; the introduction by Frenkel and Kontorowa (FK) of a truncated Fourier series to model the periodic interaction at crystalline interfaces; the invention by Frank and van der Merwe (FvdM)—using the FK model—of (interfacial) misfit dislocations as an important mechanism in accommodating misfit at epilayer-substrate interfaces; the generalization of the FvdM theory to multilayers; the application of the parabolic model by Jesser and van der Merwe to describe, for growing multilayers and superlattices, the impact of Fourier coefficients in the realization of epitaxial orientations and the stability of modes of misfit accommodation; the involvement of intralayer interaction in the latter—all features that impact on the attainment of perfection in crystallinity of thin films, a property that is so vital in the fabrication of useful uniformly thick epilayers (uniformity being another technological requirement), which also depends on misfit accommodation through the interfacial energy that function strongly in the criterion for growth modes, proposed by Bauer; and the ingenious application of the Volterra model by Matthews and others to describe misfit accommodation by dislocations in growing epilayers.

  14. Dislocation-Based Si-Nanodevices

    NASA Astrophysics Data System (ADS)

    Reiche, Manfred; Kittler, Martin; Buca, Dan; Hähnel, Angelika; Zhao, Qing-Tai; Mantl, Siegfried; Gösele, Ulrich

    2010-04-01

    The realization of defined dislocation networks by hydrophobic wafer bonding allows the electrical characterization of individual dislocations. The present paper investigates the properties of such dislocations in samples containing high dislocations densities down to only six dislocations. The current induced by a single dislocation is determined by extrapolation of the current measured for various dislocation densities. Based on our present and previously reported analyses the electronic properties of individual dislocations can be inferred. The investigations show that dislocations in the channel of metal-oxide-semiconductor field-effect transistors (MOSFETs) result in increasing drain currents even at low drain and gate voltages. Because a maximum increase of the current is obtained if a single dislocation is present in the channel, arrays of MOSFETs each containing only one dislocation could be realized on the nanometer scale. The distance of the dislocations can be well controlled by wafer bonding techniques.

  15. 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.

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

    PubMed Central

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

    2012-01-01

    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. PMID:22949701

  17. A rare fracture-dislocation of the hip in a gymnast and review of the literature

    PubMed Central

    Mitchell, J. C.; Giannoudis, P. V.; Millner, P. A.; Smith, R. M.

    1999-01-01

    Posterior fracture-dislocation of the hip is an uncommon injury in athletics and leisure activities. It is more commonly seen in high energy motor vehicle accidents and occasionally in high energy sporting activities. A rare case is reported of posterior fracture-dislocation of the hip joint that occurred in a young athlete during gymnastics. This unusual mechanism of injury illustrates the great forces sustained by the hip joint of gymnasts. Early reduction and operative treatment led to a congruent and stable hip joint. After rehabilitation, she returned to light sporting activities after six months. 


 PMID:10450489

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

    SciTech Connect

    Takeuchi, S. Asazu, H.; Nakamura, Y.; Sakai, A.; Imanishi, M.; Imade, M.; Mori, 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 of 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.

  19. Patellar Dislocations and Reduction Procedure.

    PubMed

    Ramponi, Denise

    2016-01-01

    Acute patellar dislocations are a common injury occurring in adolescents involved in sports and dancing activities. This injury usually occurs when the knee is in full extension and sustains a valgus stress on the knee. The medial patellofemoral ligament is the medial restraint that assists in stabilizing the patella from lateral dislocations. The patella usually dislocates laterally and is usually not difficult to reduce after patient evaluation and prereduction radiographs. After postreduction radiographs confirm proper position of the patella postreduction and the absence of fractures, the patient is usually treated conservatively with initial immobilization, orthopedic referral, and physical therapy.

  20. Buckling of dislocation in graphene

    NASA Astrophysics Data System (ADS)

    Yao, Yin; Wang, Shaofeng; Bai, Jianhui; Wang, Rui

    2016-10-01

    The buckling of dislocation in graphene is discussed through the lattice theory of dislocation and elastic theory. The approximate solution of the buckling is obtained based on the inner stress distribution caused by different structure of dislocations and is proved to be suitable by the simulation. The position of the highest buckling is predicted to be at the vertex of the pentagon far away from the heptagon. The buckling is strongly influenced by the internal stress and the distance between the extrusive area and stretching area, as well as the critical stress σc. The SW defect is proved to be unbuckled due to its strong interaction between extrusion and stretching.

  1. Quenched dislocation enhanced supersolid ordering.

    PubMed

    Toner, John

    2008-01-25

    I show using Landau theory that quenched dislocations can facilitate the supersolid to normal solid transition, making it possible for the transition to occur even if it does not in a dislocation-free crystal. I make detailed predictions for the dependence of the supersolid to normal solid transition temperature T_{c}(L), superfluid density rho_{S}(T,L), and specific heat C(T,L) on temperature T and dislocation spacing L, all of which can be tested against experiments. The results should also be applicable to an enormous variety of other systems, including, e.g., ferromagnets.

  2. Posterolateral elbow dislocation with entrapment of the medial epicondyle in children: a case report

    PubMed Central

    Mazzini, Juan Pretell

    2009-01-01

    Introduction Elbow dislocations in children are uncommon injuries. Dislocations with associated fractures or so-called complex dislocations of the elbow can be challenging to diagnose and treat. Case presentation A 14-year-old male had a posterolateral elbow dislocation after a fall. Closed reduction with traction was performed. Radiographs after initial reduction showed a fragment entrapped into the humero-cubital joint. Computerized tomography scan showed the fragment belonging to the medial epicondyle. Open reduction and internal fixation with a 3.0 millimeter cannulated screw was performed, with restoring of the normal function of the elbow at final follow up. Conclusion Elbow dislocations in children can be associated with bone lesions. These injuries must be suspected to avoid misleading diagnosis and achieve good results. PMID:19829829

  3. Posterior sternoclavicular dislocations--a diagnosis easily missed.

    PubMed Central

    Thomas, D. P.; Davies, A.; Hoddinott, H. C.

    1999-01-01

    Posterior dislocation of the sternoclavicular joint is a relatively rare injury and can be difficult to diagnose acutely. We report 3 cases of posterior dislocation of the sternoclavicular joint who presented to the Accident & Emergency Department within a 3 month period. All 3 patients had sustained a significant injury to the shoulder region and complained of pain around the medial clavicle. Two patients had also complained of dysphagia following the injury. Plain X-rays of the shoulder and chest were reported as normal by junior and senior medical staff. The diagnosis was delayed until CT scans were performed, and once this was established, open reduction and stabilisation was performed. Images Figure 1 Figure 2 Figure 3 p204-a PMID:10364956

  4. Dislocation sources in ordered intermetallics

    SciTech Connect

    Yoo, M.H.; Appel, F.; Wagner, R.; Mecking, H.

    1996-09-01

    An overview on the current understanding of dislocation sources and multiplication mechanisms is made for ordered intermetallic alloys of the L1{sub 2}, B2, and D0{sub 19} structures. In L1{sub 2} alloys, a large disparity of edge/screw segments in their relative mobility reduces the efficiency of a Frank-Read Type multiplication mechanism. In Fe-40%Al of the B2 structure, a variety of dislocation sources are available for <111> slip, including ones resulting from condensation of thermal vacancies. In NiAl with the relatively high APB energy, <100> dislocations may result from the dislocation decomposition reactions, the prismatic punching out from inclusion particles, and/or steps and coated layers of the surface. Internal interfaces often provide sites for dislocation multiplication, e.g., grain boundaries, sub-boundaries in Ni{sub 3}Ga, NiAl and Ti{sub 3}Al, and antiphase domain boundaries in Ti{sub 3}Al. As for the crack tip as a dislocation source, extended SISFs trailed by super-Shockley partials emanating form the cracks in Ni{sub 3}Al and Co{sub 3}Ti are discussed in view of a possible toughening mechanism.

  5. Elbow dislocation with ipsilateral diaphyseal forearm bone fracture: A rare injury report with literature review.

    PubMed

    Goni, Vijay; Behera, Prateek; Meena, Umesh Kumar; Gopinathan, Nirmal raj; Akkina, Narendranadh; Arjun, R H H

    2015-01-01

    Dislocation of the elbow along with shaft fractures of both bones of the ipsilateral forearm is a rare injury though elbow dislocation or fracture of the forearm bones may occur separately. Such injuries need a concentric reduction of the dislocation and an anatomical fixation of forearm bones for optimal functional outcomes. We report a case of elbow dislocation with fracture of the lateral condyle of the humerus along with fractures of shafts of the radius and ulna in a 44-year-old female. Closed reduction of the elbow and operative stabilization of all fractures were done with good clinical, radiological and functional outcomes in 2 years follow-up period. A significant degree of force is needed to produce a combined dislocation of a joint and fracture of bones around that joint and these complex injuries may be missed if the clinician is not aware of the possibility of such injuries. The fact that the previously reported cases had a posterolateral dislocation while our case had a posteromedial dislocation and a fracture of the lateral humeral condyle as well makes it unique in its presentation and worth reporting. We have also included an up to date literature review on this topic.

  6. A Rare Combination of Complex Elbow Dislocation and Distal Radial Fracture in Adults

    PubMed Central

    Vaishya, Raju; Krishnan, Midhun; Agarwal, Amit Kumar

    2016-01-01

    Although it is common for separate elbow joint dislocation and fracture of forearm bones to occur, it is a rare sighting for both elbow dislocation and ipsilateral fracture of the distal radius. We report a case of an anterior dislocation of the elbow with ipsilateral fracture of the distal radius. The case was treated operatively. We describe two possible mechanisms of injury for these rare injury types. The case underlines the importance of assessing the wrist in the case of an elbow fracture and vice versa. PMID:28003939

  7. A Rare Combination of Complex Elbow Dislocation and Distal Radial Fracture in Adults.

    PubMed

    Vaishya, Raju; Krishnan, Midhun; Vijay, Vipul; Agarwal, Amit Kumar

    2016-11-08

    Although it is common for separate elbow joint dislocation and fracture of forearm bones to occur, it is a rare sighting for both elbow dislocation and ipsilateral fracture of the distal radius. We report a case of an anterior dislocation of the elbow with ipsilateral fracture of the distal radius. The case was treated operatively. We describe two possible mechanisms of injury for these rare injury types. The case underlines the importance of assessing the wrist in the case of an elbow fracture and vice versa.

  8. 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.

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

    PubMed Central

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

    2010-01-01

    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. PMID:21655006

  10. On the hierarchy of interfacial dislocation structure

    NASA Astrophysics Data System (ADS)

    Balluffi, R. W.; Olson, G. B.

    1985-04-01

    Many different types of dislocations have been defined in dislocation models for grain boundaries and interphase boundaries. It is emphasized that there is no unique dislocation model for a boundary, and that the formal dislocation content depends upon the choice of the lattice correspondence relating the adjoining lattices. However, it is concluded that no problems of real physical significance arise from this lack of uniqueness. “Best≓, or most useful, descriptions often exist, and these are discussed. A hierarchy consisting of four different types of interfacial dislocations may be distinguished, which is useful in describing the dislocation content of interfaces. These entities are termed: (1) primary interfacial dislocations; (2) secondary interfacial dislocations; (3) coherency interfacial dislocations; and (4) translational interfacial dislocations. While there may be a lack of agreement on terminology in the literature, it is believed that these dislocation types are distinguishable and play unique roles in useful dislocation models for interfaces. Detailed descriptions of these dislocation types are given, and actual examples in real interfaces are presented. It is concluded that dislocation descriptions of interface structures become of purely formal significance in the limit of fully incoherent interfaces since the cores are then delocalized. The utility of various dislocation descriptions therefore depends on the degree to which various types of local coherency exist.

  11. Adult Monteggia and Olecranon Fracture Dislocations of the Elbow.

    PubMed

    Wong, Justin C; Getz, Charles L; Abboud, Joseph A

    2015-11-01

    Monteggia fractures and olecranon fracture dislocations represent complex injuries with distinct patterns of bony and soft tissue involvement. Fractures of the proximal ulna and olecranon process may lead to disruption of the proximal radioulnar joint and/or ulnohumeral joint. The keys to treatment are recognition of the pattern of injury and formation of an algorithmic surgical plan to address all components of the injury process. Complications are common and may be related to the injury spectrum itself and/or inadequate fracture alignment or fixation.

  12. Dislocation Multi-junctions and Strain Hardening

    SciTech Connect

    Bulatov, V; Hsiung, L; Tang, M; Arsenlis, A; Bartelt, M; Cai, W; Florando, J; Hiratani, M; Rhee, M; Hommes, G; Pierce, T; Diaz de la Rubia, T

    2006-06-20

    At the microscopic scale, the strength of a crystal derives from the motion, multiplication and interaction of distinctive line defects--dislocations. First theorized in 1934 to explain low magnitudes of crystal strength observed experimentally, the existence of dislocations was confirmed only two decades later. Much of the research in dislocation physics has since focused on dislocation interactions and their role in strain hardening: a common phenomenon in which continued deformation increases a crystal's strength. The existing theory relates strain hardening to pair-wise dislocation reactions in which two intersecting dislocations form junctions tying dislocations together. Here we report that interactions among three dislocations result in the formation of unusual elements of dislocation network topology, termed hereafter multi-junctions. The existence of multi-junctions is first predicted by Dislocation Dynamics (DD) and atomistic simulations and then confirmed by the transmission electron microscopy (TEM) experiments in single crystal molybdenum. In large-scale Dislocation Dynamics simulations, multi-junctions present very strong, nearly indestructible, obstacles to dislocation motion and furnish new sources for dislocation multiplication thereby playing an essential role in the evolution of dislocation microstructure and strength of deforming crystals. Simulation analyses conclude that multi-junctions are responsible for the strong orientation dependence of strain hardening in BCC crystals.

  13. Dislocation multi-junctions and strain hardening.

    PubMed

    Bulatov, Vasily V; Hsiung, Luke L; Tang, Meijie; Arsenlis, Athanasios; Bartelt, Maria C; Cai, Wei; Florando, Jeff N; Hiratani, Masato; Rhee, Moon; Hommes, Gregg; Pierce, Tim G; de la Rubia, Tomas Diaz

    2006-04-27

    At the microscopic scale, the strength of a crystal derives from the motion, multiplication and interaction of distinctive line defects called dislocations. First proposed theoretically in 1934 (refs 1-3) to explain low magnitudes of crystal strength observed experimentally, the existence of dislocations was confirmed two decades later. Much of the research in dislocation physics has since focused on dislocation interactions and their role in strain hardening, a common phenomenon in which continued deformation increases a crystal's strength. The existing theory relates strain hardening to pair-wise dislocation reactions in which two intersecting dislocations form junctions that tie the dislocations together. Here we report that interactions among three dislocations result in the formation of unusual elements of dislocation network topology, termed 'multi-junctions'. We first predict the existence of multi-junctions using dislocation dynamics and atomistic simulations and then confirm their existence by transmission electron microscopy experiments in single-crystal molybdenum. In large-scale dislocation dynamics simulations, multi-junctions present very strong, nearly indestructible, obstacles to dislocation motion and furnish new sources for dislocation multiplication, thereby playing an essential role in the evolution of dislocation microstructure and strength of deforming crystals. Simulation analyses conclude that multi-junctions are responsible for the strong orientation dependence of strain hardening in body-centred cubic crystals.

  14. Gradual reduction of chronic fracture dislocation of the ankle using ilizarov/taylor spatial frame.

    PubMed

    Tellisi, Nazzar; Deland, Jonathan T; Rozbruch, S Robert

    2011-02-01

    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.

  15. Central acetabular fracture with dislocation treated by minimally invasive plate osteosynthesis.

    PubMed

    2015-06-01

    Central acetabular fractures with dislocation are usually the result of high-energy trauma, resulting in joint incongruity, and are frequently associated with other injuries. Open reduction and internal fixation has been the standard treatment for acetabular fractures, but it is associated with extensive surgical trauma, and complications such as haematoma formation, iatrogenic nerve injury, and heterotopic ossification. We present the case of a 63-year-old female who sustained a central acetabular fracture of the hip with dislocation as a result of an automobile collision. Closed reduction of the dislocation was performed, and the fracture was managed by minimally invasive plate osteosynthesis using a specially prepared plate. At 01 year postoperatively, radiographs showed the fracture to have been well-healed with good congruity of the joint. However, heterotopic ossification of the joint was noted. The technique allowed reduction of the fracture with minimal surgical trauma.

  16. Posterior sternoclavicular Salter-Harris fracture-dislocation in a patient with unossified medial clavicle epiphysis.

    PubMed

    Beckmann, Nicholas; Crawford, Lindsay

    2016-08-01

    Sternoclavicular injuries are relatively rare, composing less than 1 % of all musculoskeletal fractures or dislocations. When sternoclavicular injuries do occur, they typically present as an isolated dislocation of the sternoclavicular joint without associated fracture of the clavicle or manubrium. However, in patients with unfused medial clavicle physis, sternoclavicular joint injuries can present as a fracture-dislocation through the unfused physis. These physeal injuries are important to recognize as the displaced epiphysis can block reduction of the sternoclavicular joint. We present a case of a 15-year-old female basketball player presenting with suspected sternoclavicular joint injury after sustaining a direct blow to the left shoulder. An initial shoulder CT confirmed the presence of the clinically suspected posterior sternoclavicular dislocation without fracture identified. An MRI of the left sternoclavicular joint was then performed for suspected physeal fracture, which confirmed the presence of a fracture through the medial clavicle physis with anterior displacement of the unossified epiphysis, blocking reduction of the metaphysis. Given the findings on MRI, the pediatric orthropedic surgeon was able to counsel the family of the high likelihood of failed closed reduction of the sternoclavicular joint requiring conversion to open reduction and internal fixation. The patient underwent successful open reduction and internal fixation of the medial clavical physeal fracture after an initial gentle attempt at closed reduction was unsuccessful.

  17. 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.

  18. Percutaneous screw fixation of fractures of the iliac wing and fracture-dislocations of the sacro-iliac joint (OTA Types 61-B2.2 and 61-B2.3, or Young-Burgess "lateral compression type II" pelvic fractures).

    PubMed

    Starr, Adam J; Walter, James C; Harris, Robert W; Reinert, Charles M; Jones, Alan L

    2002-02-01

    A technique for closed reduction and percutaneous screw fixation of fractures of the iliac wing and fracture-dislocations of the sacro-iliac joint is presented. Twenty-seven pelvic fractures were treated with attempted closed reduction followed by percutaneous screw fixation. Closed reduction failed in two patients. In the other twenty-five, closed reduction to within one centimeter of residual displacement was obtained, and was followed by stabilization with percutaneously placed cannulated screws. Complications included dislodgment of a screw from the superior pubic ramus in one patient, and partial cut-out of a screw along the inner cortex of the iliac wing in another. Two patients were lost to follow-up before fracture union occurred. The remaining twenty-three patients were followed-up for an average of twenty-seven months (range, 18-48 months). All of the fractures healed in the twenty-three patients who were not lost to follow-up. All but two of the patients who were working before injury returned to work. All but one of the patients was satisfied with the outcome of their pelvic fracture treatment. Closed reduction and percutaneous screw fixation of fractures of the posterior portion of the iliac wing yields acceptable reductions, with minimal blood loss and limited damage to the surrounding soft tissues.

  19. Thermal effects in dislocation theory

    NASA Astrophysics Data System (ADS)

    Langer, J. S.

    2016-12-01

    The mechanical behaviors of polycrystalline solids are determined by the interplay between phenomena governed by two different thermodynamic temperatures: the configurational effective temperature that controls the density of dislocations, and the ordinary kinetic-vibrational temperature that controls activated depinning mechanisms and thus deformation rates. This paper contains a review of the effective-temperature theory and its relation to conventional dislocation theories. It includes a simple illustration of how these two thermal effects can combine to produce a predictive theory of spatial heterogeneities such as shear-banding instabilities. Its main message is a plea that conventional dislocation theories be reformulated in a thermodynamically consistent way so that the vast array of observed behaviors can be understood systematically.

  20. Multiscale Theory of Dislocation Climb.

    PubMed

    Geslin, Pierre-Antoine; Appolaire, Benoît; Finel, Alphonse

    2015-12-31

    Dislocation climb is a ubiquitous mechanism playing a major role in the plastic deformation of crystals at high temperature. We propose a multiscale approach to model quantitatively this mechanism at mesoscopic length and time scales. First, we analyze climb at a nanoscopic scale and derive an analytical expression of the climb rate of a jogged dislocation. Next, we deduce from this expression the activation energy of the process, bringing valuable insights to experimental studies. Finally, we show how to rigorously upscale the climb rate to a mesoscopic phase-field model of dislocation climb. This upscaling procedure opens the way to large scale simulations where climb processes are quantitatively reproduced even though the mesoscopic length scale of the simulation is orders of magnitude larger than the atomic one.

  1. Spontaneous divergent elbow dislocation after Sauve-Kapandji procedure.

    PubMed

    Moritomo, Hisao; Izawa, Kazutaka; Murase, Tsuyoshi; Hashimoto, Hideo; Goto, Akira; Masatomi, Takashi

    2003-01-01

    This is a report on an unusual complication of the Sauve-Kapandji procedure in patients with rheumatoid arthritis. Two women with rheumatoid arthritis who previously had an ipsilateral Sauve-Kapandji procedure experienced spontaneous transverse divergent elbow dislocations without evident trauma. Their radiographs showed medial dislocation of the proximal ulna, which was separated from the radial head. The radial head and distal end of the ulnar shaft showed remarkable instability by a pronation and supination motion without the radial and ulnar shafts being separated from each other. Stress radiographic examination showed significant loosening of all ligaments except the medial collateral ligament around the elbow and did not show disruption of the interosseous membrane. A unique chronic twist radioulnar dissociation which consists of gross instability of the radial head and the distal ulna without disruption of the interosseous membrane was considered to cause instability of the humeroulnar joint, which results in medial dislocation of the proximal ulna. This report suggests that there is a direct cause and effect relationship between the residual distal ulnar instability and the development of transverse divergent dislocation of the elbow in patients with rheumatoid arthritis after the Sauve-Kapandji procedure.

  2. THE MASS STRUCTURE OF THE GALAXY CLUSTER Cl0024+1654 FROM A FULL LENSING ANALYSIS OF JOINT SUBARU AND ACS/NIC3 OBSERVATIONS

    SciTech Connect

    Umetsu, Keiichi; Okabe, Nobuhiro; Hsieh, Bau-Ching; Molnar, Sandor M.; Medezinski, Elinor; Broadhurst, Tom; Zitrin, Adi

    2010-05-10

    We derive an accurate mass distribution of the rich galaxy cluster Cl0024+1654 (z = 0.395) based on deep Subaru BR{sub c} z' imaging and our recent comprehensive strong-lensing analysis of Hubble Space Telescope/Advanced Camera for Surveys/NIC3 observations. We obtain the weak-lensing distortion and magnification of undiluted samples of red and blue background galaxies by carefully combining all color and positional information. Unlike previous work, the weak and strong lensing are in excellent agreement where the data overlap. The joint mass profile continuously steepens out to the virial radius with only a minor contribution {approx}10% in the mass from known subcluster at a projected distance of {approx_equal}700 kpc h {sup -1}. The cluster light profile closely resembles the mass profile, and our model-independent M/L{sub R} profile shows an overall flat behavior with a mean of (M/L{sub R} ) {approx_equal} 230h(M/L{sub R} ){sub sun}, but exhibits a mild declining trend with increasing radius at cluster outskirts, r {approx_gt} 0.6r{sub vir}. The projected mass distribution for the entire cluster is well fitted with a single Navarro-Frenk-White model with a virial mass, M{sub vir} = (1.2 {+-} 0.2) x 10{sup 15} M{sub sun} h {sup -1}, and a concentration, c{sub vir} = 9.2{sup +1.4}{sub -1.2}. This model fit is fully consistent with the depletion of the red background counts, providing independent confirmation. Careful examination and interpretation of X-ray and dynamical data, based on recent high-resolution cluster collision simulations, strongly suggest that this cluster system is in a post collision state, which we show is consistent with our well-defined mass profile for a major merger occurring along the line of sight, viewed approximately 2-3 Gyr after impact when the gravitational potential has had time to relax in the center, before the gas has recovered and before the outskirts are fully virialized. Finally, our full lensing analysis provides a model

  3. The Mass Structure of the Galaxy Cluster Cl0024+1654 from a Full Lensing Analysis of Joint Subaru and ACS/NIC3 Observations

    NASA Astrophysics Data System (ADS)

    Umetsu, Keiichi; Medezinski, Elinor; Broadhurst, Tom; Zitrin, Adi; Okabe, Nobuhiro; Hsieh, Bau-Ching; Molnar, Sandor M.

    2010-05-01

    We derive an accurate mass distribution of the rich galaxy cluster Cl0024+1654 (z = 0.395) based on deep Subaru BR c z' imaging and our recent comprehensive strong-lensing analysis of Hubble Space Telescope/Advanced Camera for Surveys/NIC3 observations. We obtain the weak-lensing distortion and magnification of undiluted samples of red and blue background galaxies by carefully combining all color and positional information. Unlike previous work, the weak and strong lensing are in excellent agreement where the data overlap. The joint mass profile continuously steepens out to the virial radius with only a minor contribution ~10% in the mass from known subcluster at a projected distance of sime700 kpc h -1. The cluster light profile closely resembles the mass profile, and our model-independent M/LR profile shows an overall flat behavior with a mean of langM/LR rang ~= 230h(M/LR )sun, but exhibits a mild declining trend with increasing radius at cluster outskirts, r >~ 0.6r vir. The projected mass distribution for the entire cluster is well fitted with a single Navarro-Frenk-White model with a virial mass, M vir = (1.2 ± 0.2) × 1015 M sun h -1, and a concentration, c vir = 9.2+1.4 -1.2. This model fit is fully consistent with the depletion of the red background counts, providing independent confirmation. Careful examination and interpretation of X-ray and dynamical data, based on recent high-resolution cluster collision simulations, strongly suggest that this cluster system is in a post collision state, which we show is consistent with our well-defined mass profile for a major merger occurring along the line of sight, viewed approximately 2-3 Gyr after impact when the gravitational potential has had time to relax in the center, before the gas has recovered and before the outskirts are fully virialized. Finally, our full lensing analysis provides a model-independent constraint of M 2D(

  4. [Injuries of the elbow joint].

    PubMed

    Lill, H; Voigt, C

    2004-10-01

    Injuries of the elbow joint increase along with increased athletic activity and life expectancy. Knowledge of anatomy and biomechanics is important for understanding injury patterns, specific diagnosis, and therapy. Here we classify the most frequent elbow injuries such as dislocation, ligamentous instability, and fracture of the radial head, processus coronoideus, olecranon, and distal humerus based on joint anatomy, biomechanics, clinical examination, and imaging. Specific therapies are described.

  5. Speed's Procedure Used to Treat Chronic Elbow Dislocation.

    PubMed

    Thomas, D K

    2015-11-05

    In this report, operative treatment of chronic elbow dislocation using Speed's technique is described. Reports on this phenomenon are infrequent. This clinically important pathology is quite uncommon but impacts negatively on a patient's functionality and normal daily activities. We present the case of a 53-year old woman with a missed diagnosis of elbow dislocation. The patient was unable to function because of pain, stiffness and loss of motion. Her diagnosis was missed in the emergency department and in a general practitioner's office. A correct diagnosis was made three months later. The consultant organized an early date for surgery. The definitive treatment entailed open reduction, VY plasty of triceps and supplementary fixation using K wires through the elbow joint (Speed's Procedure). The occurrence, patho-mechanics, operative technique and its outcome are discussed.

  6. Palmar-divergent dislocation of the scaphoid and the lunate.

    PubMed

    Komura, Shingo; Yokoi, Tatsuo; Suzuki, Yasushi

    2011-03-01

    We describe a patient with palmar-divergent dislocation of the scaphoid and lunate. After successful closed reduction, the scapholunate and lunotriquetral ligaments were sutured through the dorsal approach, and the anterior capsule was sutured through the palmar approach. The scapholunate and lunotriquetral joints were fixed with Kirschner wires for 7 weeks. At the 1-year follow-up, magnetic resonance imaging showed no evidence of avascular necrosis of the scaphoid or lunate, and radiographs showed no evidence of the dorsal and volar intercalated segment instability patterns associated with carpal instability. However, flexion of the scaphoid and a break in Gilula's line remained. To our knowledge, this is the first report showing treatment of palmar-divergent dislocation of the scaphoid and lunate by suturing the carpal interosseous ligaments.

  7. Open antero-lateral dislocation of the elbow. A case report

    PubMed Central

    Alonso, Juan A; Roy, Bibas R; Shaw, David L

    2002-01-01

    Background Open dislocations are infrequent, often associated with damage to the neuro vascular structures. We present an unusual case of an open antero-lateral dislocation of the elbow, which was not associated with any vascular or neural injury. Case presentation A 34 year female dance instructor sustained an open dislocation of her elbow. Surgical exploration was undertaken. No major neurovascular injury was present. There was almost complete disruption of all the muscular and ligamentous attachments to the distal humerus and the proximal radius and ulna, which were not formally repaired during surgery. The elbow was found to be very unstable, and was placed in a back slab. The functional recovery was complete in about six months, the patient regaining full range of elbow movement. Elbow dislocations without associate fractures are adequately treated by manipulation and reduction, in spite of the almost complete disruption of the soft tissues around the joint. PMID:11806760

  8. Treatment of Locked Posterior Shoulder Dislocation With Bone Defect.

    PubMed

    Khira, Yousuf M; Salama, Adel M

    2017-03-14

    Locked posterior shoulder dislocation is an uncommon condition and is associated with a reverse Hill-Sachs lesion in 50% of cases. The condition is likely to occur in cases of violent trauma, seizures, or electric shock. Unrecognized dislocation with humeral head fracture affects joint function and humeral head vascularity and may lead to chronic instability, osteonecrosis, and osteoarthritis. A group of 12 patients, including 10 men and 2 women, with neglected locked posterior shoulder dislocation with a reverse Hill-Sachs lesion were treated with the modified McLaughlin technique. The added bone graft from the iliac crest was impacted in the defect and fixed with screws. Mean follow-up was 30 months (range, 24-48 months). The range of forward flexion was 150˚ to 175˚ (average, 165˚), external rotation ranged from 60˚ to 80˚ (average, 75˚), internal rotation ranged from 40˚ to 60˚ (average, 50˚), and average abduction was 150˚ (range, 145˚-160˚). The modified University of California Los Angeles (UCLA) scoring system was used for postoperative clinical evaluation. Total UCLA scores immediately postoperatively ranged from 22 to 28 points (average, 26.5 points) and averaged 30 points (range, 28-33 points) at last follow-up. No recurrence of dislocation occurred during the follow-up period. Of the study patients, 10 returned to their previous job and 2 modified their manual work. The modified McLaughlin technique with added iliac crest bone graft to fill the defect and prevent humeral head deformity is a successful technique for the treatment of patients with chronic locked posterior shoulder dislocation. [Orthopedics. 201x; xx(x):xx-xx.].

  9. Evolution of geometrically necessary dislocation density from computational dislocation dynamics

    NASA Astrophysics Data System (ADS)

    Guruprasad, P. J.; Benzerga, A. A.

    2009-07-01

    This paper presents a method for calculating GND densities in dislocation dynamics simulations. Evolution of suitably defined averages of GND density as well as maps showing the spatial nonuniform distribution of GNDs are analyzed under uniaxial loading. Focus is laid on the resolution dependence of the very notion of GND density, its dependence upon physical dimensions of plastically deformed specimens and its sensitivity to initial conditions. Acknowledgments Support from the National Science Foundation (CMMI-0748187) is gratefully acknowledged.

  10. Solute drag on perfect and extended dislocations

    NASA Astrophysics Data System (ADS)

    Sills, R. B.; Cai, W.

    2016-04-01

    The drag force exerted on a moving dislocation by a field of mobile solutes is studied in the steady state. The drag force is numerically calculated as a function of the dislocation velocity for both perfect and extended dislocations. The sensitivity of the non-dimensionalized force-velocity curve to the various controlling parameters is assessed, and an approximate analytical force-velocity expression is given. A non-dimensional parameter S characterizing the strength of the solute-dislocation interaction, the background solute fraction ?, and the dislocation character angle ?, are found to have the strongest influence on the force-velocity curve. Within the model considered here, a perfect screw dislocation experiences no solute drag, but an extended screw dislocation experiences a non-zero drag force that is about 10 to 30% of the drag on an extended edge dislocation. The solutes can change the spacing between the Shockley partials in both stationary and moving extended dislocations, even when the stacking fault energy remains unaltered. Under certain conditions, the solutes destabilize an extended dislocation by either collapsing it into a perfect dislocation or causing the partials to separate unboundedly. It is proposed that the latter instability may lead to the formation of large faulted areas and deformation twins in low stacking fault energy materials containing solutes, consistent with experimental observations of copper and stainless steel containing hydrogen.

  11. Theory of interacting dislocations on cylinders

    NASA Astrophysics Data System (ADS)

    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.

  12. Paediatric medial epicondyle fracture without elbow dislocation associated with intra-articular ulnar nerve entrapment.

    PubMed

    Elbashir, Mohamed; Domos, Peter; Latimer, Mark

    2015-11-05

    Elbow fractures are not uncommon in children, and some are associated with neurovascular injuries. Having a nerve injury in an elbow fracture without dislocation is rare and was not described in the literature. Here, we have reported probably the first case of an ulnar nerve injury in an elbow fracture without dislocation. A 9-year-old female presented to the emergency department after falling off a monkey bar. She had a painful, swollen and tender right elbow with no history or clinical signs of an elbow dislocation but had complete ulnar nerve palsy. She was managed initially with analgesia and plaster application and was taken directly to the operating theatre. Examination under anaesthesia revealed no elbow joint instability. The ulnar nerve was found entrapped between the trochlea and proximal ulna, intra-articularly. The medial epicondyle was also found avulsed from the humerus, with an incarcerated medial epicondylar fragment in the elbow joint.

  13. Paediatric medial epicondyle fracture without elbow dislocation associated with intra-articular ulnar nerve entrapment

    PubMed Central

    Elbashir, Mohamed; Domos, Peter; Latimer, Mark

    2015-01-01

    Elbow fractures are not uncommon in children, and some are associated with neurovascular injuries. Having a nerve injury in an elbow fracture without dislocation is rare and was not described in the literature. Here, we have reported probably the first case of an ulnar nerve injury in an elbow fracture without dislocation. A 9-year-old female presented to the emergency department after falling off a monkey bar. She had a painful, swollen and tender right elbow with no history or clinical signs of an elbow dislocation but had complete ulnar nerve palsy. She was managed initially with analgesia and plaster application and was taken directly to the operating theatre. Examination under anaesthesia revealed no elbow joint instability. The ulnar nerve was found entrapped between the trochlea and proximal ulna, intra-articularly. The medial epicondyle was also found avulsed from the humerus, with an incarcerated medial epicondylar fragment in the elbow joint. PMID:26546588

  14. Posterior dislocation of the elbow as an unusual presentation after a total hip replacement: a case report

    PubMed Central

    Periasamy, Kumar; Meek, Dominic; Crossman, Paul

    2008-01-01

    Introduction Posterior dislocation of the elbow is usually associated with trauma to the joint with a reported incidence of 3%to 6%. Chronic instability is usually symptomatic following the initial injury. Case presentation We report a case of posterior dislocation of the elbow occurring in a patient while using her arm to lift herself using a monkey pole on the second day following a total hip replacement. The dislocation was reduced under sedation in the ward. There were no signs or symptoms suggesting any joint hypermobility syndrome in the patient. Follow up 4 months following the injury revealed a complete recovery in the range of motion and a pain free elbow. There were no signs and symptoms of any instability. Conclusion This is the first time such a case is reported in the literature. It certainly demonstrates that even in the absence of instability a patient can be predisposed to low energy dislocation of the elbow. PMID:18254950

  15. [Results of surgical treatment for acromioclavicular dislocation using a modified Mitchell method].

    PubMed

    Król, M; Jarco, K; Sleczkowski, M; Delimat, J; Szot, J

    2000-01-01

    The paper presents the results of surgical treatment in acromioclavicular dislocation (grade III according to Tossy) in 53 patients. Joint reconstruction was performed using Mitchell's modified method--acromioclavicular reconstruction was achieved by applying a with Dallos poliester fiber prosthesis. Clinically in 90.5% of the cases a good or excellent result was achieved.

  16. 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.

  17. Imaging of the patellofemoral joint.

    PubMed

    Thomas, Stephen; Rupiper, David; Stacy, G Scott

    2014-07-01

    The patellofemoral (PF) joint is a complex articulation, with interplay between the osseous and soft tissue structures to maintain the balance between knee mobility and stability. Disorders of the PF joint can be a source of anterior knee pain (AKP). In this article, radiographic and magnetic resonance imaging of the PF joint are reviewed, including normal anatomy, imaging techniques, and imaging-based measurements. Common imaging findings associated with AKP are reviewed, including symptomatic normal variants, tendinopathy, apophysitis, osteoarthritis, chondromalacia patella, trochlear dysplasia, excessive lateralization of tibial tuberosity, patellar maltracking, patellar dislocation and fractures, anterior bursitis, Morel-Lavallée effusions, and fat pad edema.

  18. [Case report and literature review: elbow fracture dislocation in children].

    PubMed

    Guzmdn, R; Rincón, D; Camacho, J

    2015-01-01

    Elbow dislocation in children is a very infrequent traumatic event which was first described by Stimson in 1900 and then by Tachdjian in 1990. Its estimated incidence ranges from 3% to 6% of all elbow injuries, peaking at 13-14 years. Elbow trauma is classified considering the direction in which the proximal radioulnar joint shifts with respect to the humerus, into posterior and anterior dislocation. The former is the most frequent and accounts for 95% of cases. Elbow fracture dislocation is an even rarer event. The incidence rate of avulsion fracture of the medial epicondyle is 25-36%, of the lateral condyle 4%, of the olecranon 1.7%, of the radial head 8%, of the coronoid process 3.5%, and others, 3.5%. At present there is no consensus in the literature on how to treat this type of lesions, particularly because some authors advocate nonsurgical management, while others propose surgical management as the definitive treatment. What is clear, however, is that a late diagnosis or untimely treatment may affect the child's growth and lead to serious complications. The purpose of this study is to share our experience and good results with the surgical management of these infrequent cases.

  19. Atlanto-axial dislocation complicating a type II odontoid fracture. Reduction and final fixation.

    PubMed

    Riouallon, G; Pascal-Moussellard, H

    2014-05-01

    A case of traumatic posterolateral C1-C2 dislocation associated with odontoid fracture is reported. This is a rare case of traumatic posterolateral C1-C2 dislocation associated with odontoid fracture. Its management is discussed. A traumatic dislocation of atlanto-axial joint associated with an odontoid fracture remains a rare injury. No case of posterior dislocation has been reported so far in the literature with this type of management. The case is of a 25 year-old-man with a primary atlanto-axial posterolateral dislocation associated with a type II displaced odontoid fracture without any neurological complication. The patient underwent gentle traction during 24 hours with a halo frame. An incomplete reduction was achieved. Two days later, a complete reduction was obtained thanks to a preoperative manual traction maintained by a Mayfield (R) modified skull clamp. Anterior C1-C2 fixation was performed according to Vaccaro's technique. The patient wore a cervical collar and underwent physiotherapy during three months. To our best knowledge, this case represents the first traumatic atlanto-axial dislocation associated with an odontoid fracture which was treated through retropaharyngeal approach. This had been rendered possible thanks to the final reduction maneuver in extension.

  20. Late developmental dislocation of the hip after initial normal evaluation: a report of five cases.

    PubMed

    Raimann, Alfredo; Baar, Alejandro; Raimann, Roberto; Morcuende, Jose A

    2007-01-01

    Developmental dysplasia of the hip (DDH) denotes a wide spectrum of pathologies ranging from hip instability to frank dislocation. The current understanding is that cases of late diagnosis were missed during the newborn period. However, there is some evidence that a number of hip subluxations or dislocations may have been clinically stable in the neonatal period, but dislocate late. We present 5 cases of otherwise healthy children with normal physical examinations and hip radiographs in the first 3 months of life who later developed hip dislocations. Four of the 5 cases required surgical open reduction. In light of these cases and others in the literature, normal neonatal screening for DDH does not assure that continued normal development of the hip joint will happen. Our study confirms the existence of another entity in the wide spectrum of DDH: the late hip dislocation. Therefore, hip evaluations should be continued beyond the neonatal period until the child begins to walk. Parents should be informed that hip dislocation can occur in a late form, and they should be encouraged to take their children for repeated evaluations even if the neonatal screening is normal.

  1. An Unusual Traumatic Presentation: Luxatio Erecta Humeri and Concomitant Hip Dislocation

    PubMed Central

    Anarat, Berkan; Ersin, Mehmet; Erşen, Ali; Şen, Cengiz

    2016-01-01

    Introduction. Inferior dislocation of the glenohumeral joint, known as luxatio erecta humeri, and posterior hip dislocation are both rare presentations in the emergency department. The most common aetiology is falling for luxatio erecta humeri. The aim of this manuscript was to present a unique case in terms of luxatio erecta humeri, which has a different aetiology, treatment method, and concomitant injury. Presentation of Case. We report a construction worker who was rescued from a collapsed building who presented with both luxatio erecta humeri and complex posterior hip dislocation. An orthopaedic surgeon reducted luxatio erecta humeri with a one-step reduction technique under procedural anaesthesia as soon as the patient's vital signs were stable. Discussion. Different concomitant injuries and various injury mechanisms have been described in regard to inferior shoulder dislocation in the literature. However, posterior dislocation of the hip as a concomitant distant region injury and trapping as an injury mechanism for luxatio erecta humeri are being described for the first time in this case report. Two reduction manoeuvers, one-step and two-step, have been used for this dislocation. Some authors suggested that a two-step manoeuver can be more easy to apply. In our specific case, luxatio erecta was easily reducted by a single operator in a single attempt. Conclusion. Luxatio erecta humeri may occur from trapping and complex injuries can accompany luxatio erecta humeri in patients with multiple trauma. A one-step closed reduction can be easily applied by a single operator under procedural anaesthesia. PMID:28078152

  2. Factors predisposing to dislocation of the Thompson hemiarthroplasty: 22 dislocations in 338 patients.

    PubMed

    Pajarinen, Jarkko; Savolainen, Vesa; Tulikoura, Ilkka; Lindahl, Jan; Hirvensalo, Eero

    2003-02-01

    In a series of 338 patients, we have retrospectively analyzed technical and anatomical factors, which may predispose to a dislocation of the Thompson hemiprosthesis. 22 patients (7%) had at least 1 dislocation during the 6-month follow-up. The most significant independent factor predisposing to dislocation was the use of a posterior approach (dislocation rate 16%). We examined the radiographs and data on operations in the 22 patients, using 79 random patients without dislocation as controls. Factors correlating with an increase in the incidence of dislocation were the length of the residual femoral neck > 0.5 cm in short patients (< 165 cm), and considerable change in the postoperative offset of the hip. Acetabular measurements showed no correlation to the dislocation. Our findings suggest that the main factors predicting dislocation are technical and not related to anatomical measurements.

  3. Massively-Parallel Dislocation Dynamics Simulations

    SciTech Connect

    Cai, W; Bulatov, V V; Pierce, T G; Hiratani, M; Rhee, M; Bartelt, M; Tang, M

    2003-06-18

    Prediction of the plastic strength of single crystals based on the collective dynamics of dislocations has been a challenge for computational materials science for a number of years. The difficulty lies in the inability of the existing dislocation dynamics (DD) codes to handle a sufficiently large number of dislocation lines, in order to be statistically representative and to reproduce experimentally observed microstructures. A new massively-parallel DD code is developed that is capable of modeling million-dislocation systems by employing thousands of processors. We discuss the general aspects of this code that make such large scale simulations possible, as well as a few initial simulation results.

  4. Enabling Strain Hardening Simulations with Dislocation Dynamics

    SciTech Connect

    Arsenlis, A; Cai, W

    2006-12-20

    Numerical algorithms for discrete dislocation dynamics simulations are investigated for the purpose of enabling strain hardening simulations of single crystals on massively parallel computers. The algorithms investigated include the /(N) calculation of forces, the equations of motion, time integration, adaptive mesh refinement, the treatment of dislocation core reactions, and the dynamic distribution of work on parallel computers. A simulation integrating all of these algorithmic elements using the Parallel Dislocation Simulator (ParaDiS) code is performed to understand their behavior in concert, and evaluate the overall numerical performance of dislocation dynamics simulations and their ability to accumulate percents of plastic strain.

  5. Elbow dislocation with ipsilateral distal radius fracture

    PubMed Central

    Meena, Sanjay; Trikha, Vivek; Kumar, Rakesh; Saini, Pramod; Sambharia, Abhishek Kumar

    2013-01-01

    Elbow dislocation associated with ipsilateral distal radius fracture is a rare pattern of injury, although it is common for elbow dislocation and forearm fractures to occur separately. We report a rare case of a 20-year-old male who had a posterior elbow dislocation and ipsilateral distal radius fracture. Elbow dislocation was first reduced in extension and distal radius fracture was then reduced in flexion. Both the injuries were conservatively managed. At 6 months follow-up, the patient had no pain in his elbow and minimal pain in his wrist on heavy lifting and had resumed his work as a laborer. PMID:24082758

  6. Elbow dislocation with ipsilateral distal radius fracture.

    PubMed

    Meena, Sanjay; Trikha, Vivek; Kumar, Rakesh; Saini, Pramod; Sambharia, Abhishek Kumar

    2013-07-01

    Elbow dislocation associated with ipsilateral distal radius fracture is a rare pattern of injury, although it is common for elbow dislocation and forearm fractures to occur separately. We report a rare case of a 20-year-old male who had a posterior elbow dislocation and ipsilateral distal radius fracture. Elbow dislocation was first reduced in extension and distal radius fracture was then reduced in flexion. Both the injuries were conservatively managed. At 6 months follow-up, the patient had no pain in his elbow and minimal pain in his wrist on heavy lifting and had resumed his work as a laborer.

  7. Microdiffraction Analysis of Hierarchical Dislocation Organization

    SciTech Connect

    Barabash, R.I.; Ice, G.E.

    2007-12-19

    This article describes how x-ray microdiffraction is influenced by the number, kind, and organization of dislocations. Particular attention is placed on micro-Laue diffraction, where polychromatic x-rays are diffracted into characteristic Laue patterns that are sensitive to the dislocation content and arrangement. Diffraction is considered for various stages of plastic deformation. For early stages of plastic deformation with random dislocation spacing, the intensity in reciprocal space is redistributed about Laue spots with a length scale proportional to the number of dislocations within the sample volume and with a characteristic shape that depends on the kinds of dislocations and the momentum transfer vector. Unpaired dislocations that contribute to lattice rotations cause the largest redistribution of scattered intensity. In later stages of plastic deformation, strong interactions between individual dislocations cause them to organize into correlated arrangements. Here again, xray diffraction Laue spots are broadened in proportion to the number of excess (unpaired) dislocations inside the wall and to the total number of unpaired walls, but the broadening can be discontinuous. With microdiffraction it is possible to quantitatively test models of dislocation organization.

  8. Congenital dislocation of the patella - clinical case.

    PubMed

    Miguel Sá, Pedro; Raposo, Filipa; Santos Carvalho, Manuel; Alegrete, Nuno; Coutinho, Jorge; Costa, Gilberto

    2016-01-01

    Congenital patellar dislocation is a rare condition in which the patella is permanently dislocated and cannot be reduced manually. The patella develops normally as a sesamoid bone of the femur. This congenital dislocation results from failure of the internal rotation of the myotome that forms the femur, quadriceps muscle and extensor apparatus. It usually manifests immediately after birth, although in some rare cases, the diagnosis may be delayed until adolescence or adulthood. Early diagnosis is important, thereby allowing surgical correction and avoiding late sequelae, including early degenerative changes in the knee. A case of permanent dislocation of the patella is presented here, in a female child aged seven years.

  9. 21 CFR 888.3480 - Knee joint femorotibial metallic constrained cemented prosthesis.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 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...

  10. 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...

  11. 21 CFR 888.3480 - Knee joint femorotibial metallic constrained cemented prosthesis.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 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...

  12. 21 CFR 888.3480 - Knee joint femorotibial metallic constrained cemented prosthesis.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 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...

  13. 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.

  14. 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.

  15. Irreducible dislocation of the radial head with undisplaced olecranon fracture in a child: a case report.

    PubMed

    Takase, Katsumi; Mizuochi, Jun

    2011-09-01

    Irreducible isolated dislocation of the radial head is a rare injury. In this study, we describe a patient with irreducible dislocation of the radial head associated with an undisplaced fracture of the olecranon. A 6-year-old girl fell down while walking and suffered injury to the posterior aspect of the proximal ulnar shaft with the right elbow in a slightly flexed position. Plain radiographs of the elbow revealed an anterior-medial dislocation of the radial head and an undisplaced fracture of the olecranon. However, the attempted closed reduction was not successful. An open reduction was then performed through a lateral approach. The radial head was found to be protruding through a buttonhole tear of the anterior joint capsule, causing the joint to become interposed between the articular surfaces of the joint, precluding closed reduction. Once the interposed capsule was extricated from the joint, the radial head could be easily reduced. At this point, no tear of the annular ligament was observed. Six months after the surgery, the patient was able to use her elbow fully and without pain. The range of motion was 0-140° for both extension and flexion and 90° for pronation and supination. Plain radiographs revealed a united bone of the olecranon and good reduction of the radial head. The radial head pushed through the tear of the anterior joint capsule. This buttonhole effect on the radial head prevented closed reduction of the radial head.

  16. Joint swelling

    MedlinePlus

    Swelling of a joint ... Joint swelling may occur along with joint pain . The swelling may cause the joint to appear larger or abnormally shaped. Joint swelling can cause pain or stiffness. After an ...

  17. Posteromedial dislocation of the elbow with lateral condyle fracture in children.

    PubMed

    Cheng, Pen-Gang; Chang, Wei-Ning; Wang, Matthew N

    2009-02-01

    Posteromedial dislocation of the elbow with lateral condyle fracture is a rare injury, and only a few cases have been reported in the literature. We report 3 children who had posteromedial dislocation of the elbow with Milch type II lateral condylar fracture of the distal humerus. Major complications included malunion, nonunion of the fracture, heterotophic calcification and elbow subluxation. From our experience and a review of the literature, open anatomical reduction and internal fixation of the lateral condyle fracture is the mainstay of treatment for these children. Poor reduction of the lateral condyle fracture results in incongruity of the joint surface and leads to poor results.

  18. Can posterior hip fracture-dislocation occur in indoor football (futsal)? A report of two cases.

    PubMed

    Yasin, Faissal Nor; Singh, Vivek Ajit

    2009-01-01

    Hip fracture-dislocation is extremely rare in sports and is most frequently seen after road traffic accidents. This injury is associated with considerable long-term disability and rapidly progressive joint degeneration. This case report illustrates two cases of hip fracture dislocation that occurred while playing recreational indoor football (futsal). Futsal is a fast-emerging recreational sport in Malaysia and we are now beginning to see high-impact injuries rarely encountered in recreational sports. Therefore, futsal cannot be taken lightly and it is important to take adequate precautions to prevent serious injuries when participating in such sports.

  19. Quantum dislocations in solid Helium-4

    NASA Astrophysics Data System (ADS)

    Aleinikava, Darya

    In this thesis the following problems on properties of solid 4He are considered: (i) the role of long-range interactions in suppression of dislocation roughening at T = 0; (ii) the combined effect of 3He impurities and Peierls potential on shear modulus softening; (iii) the dislocation superclimb and its connection to the phenomenon of "giant isochoric compressibility"; (iv) non-linear dislocation response to the applied stress and stress-induces dislocation roughening as a I-order phase transition in 1D at finite temperature. First we investigate the effect of long-range interactions on the state of edge dislocation at T = 0. Such interactions are induced by elastic forces of the solid. We found that quantum roughening transition of a dislocation at T = 0 is completely suppressed by arbitrarily small long-range interactions between kinks. A heuristic argument is presented and the result has been verified by numerical Monte-Carlo simulations using Worm Algorithm in J-current model. It was shown that the Peierls potential plays a crucial role in explaining the elastic properties of dislocations, namely shear modulus softening phenomenon. The crossover from T = 0 to finite temperatures leads to intrinsic softening of the shear modulus and is solely controlled by kink typical energy. It was demonstrated that the mechanism, involving only the binding of 3He impurities to the dislocations, requires an unrealistically high concentrations of defects (or impurities) in order to explain the shear modulus phenomenon and therefore an inclusion of Peierls potential in consideration is required. Superclimbing dislocations, that is the edge dislocations with the superfluidity along the core, were investigated. The theoretical prediction that superclimb is responsible for the phenomenon of "giant isochoric compressibility" was confirmed by Monte-Carlo simulations. It was demonstrated that the isochoric compressibility is suppressed at low temperatures. The dependence of

  20. Dislocated interests and climate change

    NASA Astrophysics Data System (ADS)

    Davis, Steven J.; Diffenbaugh, Noah

    2016-06-01

    The predicted effects of climate change on surface temperatures are now emergent and quantifiable. The recent letter by Hansen and Sato (2016 Environ. Res. Lett. 11 034009) adds to a growing number of studies showing that warming over the past four decades has shifted the distribution of temperatures higher almost everywhere, with the largest relative effects on summer temperatures in developing regions such as Africa, South America, southeast Asia, and the Middle East (e.g., Diffenbaugh and Scherer 2011 Clim. Change 107 615-24 Anderson 2011 Clim. Change 108 581; Mahlstein et al 2012 Geophys. Res. Lett. 39 L21711). Hansen and Sato emphasize that although these regions are warming disproportionately, their role in causing climate change—measured by cumulative historical CO2 emissions produced—is small compared to the US and Europe, where the relative change in temperatures has been less. This spatial and temporal mismatch of climate change impacts and the burning of fossil fuels is a critical dislocation of interests that, as the authors note, has ‘substantial implications for global energy and climate policies.’ Here, we place Hansen and Sato’s ‘national responsibilities’ into a broader conceptual framework of problematically dislocated interests, and briefly discuss the related challenges for global climate mitigation efforts.

  1. Axial-Plane Biomechanical Evaluation of 2 Suspensory Cortical Button Fixation Constructs for Acromioclavicular Joint Reconstruction

    PubMed Central

    Struhl, Steven; Wolfson, Theodore S.; Kummer, Frederick

    2016-01-01

    Background: Although numerous suture-button fixation techniques for acromioclavicular (AC) joint reconstruction have been validated with biomechanical testing in the superior direction, clinical reports continue to demonstrate high rates of construct slippage and breakage. Purpose: To compare the stability of a novel closed-loop double Endobutton construct with a commercially available cortical button system in both the axial and superior directions. Study Design: Controlled laboratory study. Methods: Six matched pairs of fresh-frozen cadaveric upper extremities were anatomically dissected and prepared to simulate a complete AC joint dislocation. One side of each pair was reconstructed with the double Endobutton (DE) construct and other side with the dog bone button (DB) construct. The specimens were then tested using a materials testing machine, determining initial superior and axial displacements with a preload, and then cyclically loaded in the axial direction with 70 N for 5000 cycles. Displacement was again measured with the same preloads at fixed cycle intervals. The specimens were then loaded superiorly to failure. Results: At 5000 cycles, the mean axial displacement was 1.7 mm for the DB group and 1.2 mm for the DE group (P = .19), and the mean superior displacement was 1.1 mm for the DB group and 0.7 mm for the DE group (P = .32). Load at failure was similar (558 N for DE, 552 N for DB; P = .96). There was no statistically significant difference in the modes of failure. Conclusion: Biomechanical testing of both constructs showed similar fixation stability after cyclical axial loading and similar loads to failure. Clinical Relevance: The strength of both constructs after cyclical loading in the axial plane and load-to-failure testing in the superior plane validate their continued clinical use for achieving stability in AC joint reconstruction procedures. PMID:28210644

  2. 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.

  3. Computed tomography arthrography in traumatic hip dislocation. Intra-articular and capsular findings.

    PubMed

    Glynn, T P; Kreipke, D L; DeRosa, G P

    1989-01-01

    The newer diagnostic modalities such as computed tomography and magnetic resonance imaging are becoming increasingly used in the evaluation of joint trauma. The combination of computed tomography and arthrography can also be of significant diagnostic value in certain specific situations. In our case report, we describe its use in post-traumatic recurrent hip dislocation and its value, not only in depicting a posterior capsular tear, but also in the diagnosis of an internal joint derangement which may contribute to incongruous reduction of the hip joint.

  4. Traumatic hip dislocation with incomplete reduction due to soft-tissue interposition in a 4-year-old boy.

    PubMed

    Burgos, J; Gonzalez-Herranz, P; Ocete, G

    1995-01-01

    The case of a traumatic dislocation of the left hip in a 4-year-old boy is presented. After an initial attempt at reduction under general anesthesia, a permanent deformity in the flexion of the hip remained, and there was radiographic evidence of a nonconcentric reduction. Computed tomography (CT) showed interposition in the posterior part of the joint. Under general anesthesia, the mobilization of the hip reduced the dislocation correctly, removing the necessity of open treatment. This case stresses the need for early diagnosis of this serious complication and closed reduction of the joint, avoiding the poor results of open and deferred treatments.

  5. Arthroscopic Lysis of Arthrofibrosis of the Fifth Tarsometatarsal Joint.

    PubMed

    Lui, Tun Hing

    2015-12-01

    Loss of motion of the fifth tarsometatarsal joint can be a cause of lateral foot pain after Lisfranc fracture-dislocation or fracture of the fifth metatarsal tubercle. Arthroscopic lysis of the joint can be an effective surgical treatment with the advantage of minimal soft-tissue trauma and early vigorous mobilization of the joint. The lysis can be extended to the fourth tarsometatarsal joint and the adjacent tendons if indicated.

  6. Palmar dislocation of scaphoid and lunate.

    PubMed

    Idrissi, Khalid Koulali; Galiua, Farid

    2011-09-28

    A palmar dislocation of scaphoid and lunate is uncommon. We have found only 19 reported cases in the literature. We reported a simultaneous, divergent dislocation. The closed reduction followed by percutaneous pinning has given a good result without avascular necrosis of any carpal bone.

  7. Statistics of dislocation pinning at localized obstacles

    SciTech Connect

    Dutta, A.; Bhattacharya, M. 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 of 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.

  8. 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.

  9. Dislocation generation during early stage sintering.

    NASA Technical Reports Server (NTRS)

    Sheehan, J. E.; Lenel, F. V.; Ansell, G. S.

    1973-01-01

    Discussion of the effects of capillarity-induced stresses on dislocations during early stage sintering. A special version of Hirth's (1963) theoretical calculation procedures modified to describe dislocation nucleation on planes meeting the sintering body's neck surface obliquely is shown to predict plastic flow at stress levels know to exist between micron size metal particles in the early stages of sintering.

  10. Posterior dislocation of the shoulder in athletes.

    PubMed

    Samilson, R L; Prieto, V

    1983-07-01

    Although posterior dislocation of the shoulder is a rare injury in athletes, failure to recognize and properly manage acute dislocation may have serious consequences. The article discusses the incidence, mechanism of injury, classification, pathologic findings, clinical and radiologic diagnosis, and management.

  11. Characterization of Geometrically Necessary Dislocation Content with EBSD-Based Continuum Dislocation Microscopy

    NASA Astrophysics Data System (ADS)

    Ruggles, Timothy J.

    Modeling of plasticity is often hampered by the difficulty in accurately characterizing dislocation density on the microscale for real samples. It is particularly difficult to resolve measured dislocation content onto individual dislocation systems at the length scales most commonly of interest in plasticity studies. Traditionally, dislocation content is analyzed at the continuum level using the Nye tensor and the fundamental relation of continuum dislocation theory to interpret information measured by diffraction techniques, typically EBSD or High Resolution EBSD. In this work the established Nye-Kroner method for resolving measured geometrically necessary dislocation content onto individual slip systems is assessed and extended. Two new methods are also presented to relieve the ambiguity of the Nye-Kroner method. One of these methods uses modified classical dislocation equations to bypass the Nye-Kroner relation, and the other estimates the bulk dislocation density via the entry-wise one-norm of the Nye tensor. These methods are validated via a novel simulation of distortion fields around continuum fields of dislocation density based on classical lattice mechanics and then applied to actual HR-EBSD scans of a micro-indented single crystals of nickel and tantalum. Finally, a detailed analysis of the effect of the spacing between points in an EBSD scan (which is related to the step size of the numerical derivatives used in EBSD dislocation microscopy) on geometrically necessary dislocation measurements is conducted.

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

    SciTech Connect

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

    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. 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.

  13. 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

  14. Dislocation core radii near elastic stability limits

    NASA Astrophysics Data System (ADS)

    Sawyer, C. A.; Morris, J. W., Jr.; Chrzan, D. C.

    2013-04-01

    Recent studies of transition metal alloys with compositions that place them near their limits of elastic stability [e.g., near the body-centered-cubic (BCC) to hexagonal-close-packed (HCP) transition] suggest interesting behavior for the dislocation cores. Specifically, the dislocation core size is predicted to diverge as the stability limit is approached. Here a simple analysis rooted in elasticity theory and the computation of ideal strength is used to analyze this divergence. This analysis indicates that dislocation core radii should diverge as the elastic limits of stability are approached in the BCC, HCP, and face-centered-cubic (FCC) structures. Moreover, external stresses and dislocation-induced stresses also increase the core radii. Density functional theory based total-energy calculations are combined with anisotropic elasticity theory to compute numerical estimates of dislocation core radii.

  15. Acute traumatic posterior elbow dislocation in children.

    PubMed

    Lieber, Justus; Zundel, Sabine M; Luithle, Tobias; Fuchs, Jörg; Kirschner, Hans-Joachim

    2012-09-01

    Traumatic posterior dislocation of the elbow is often associated with significant morbidity and incomplete recovery. The aim of this study was to retrospectively analyse the outcome of 33 children (median age 10.8 years). Patients underwent reduction and assessment of stability under general anaesthesia. Pure dislocations (n=10) were immobilized, whereas unstable fractures (n=23) were stabilized. Refixation of ligaments was performed if stability was not achieved by fracture stabilization alone. Immobilization was continued for 26 (pure dislocations) or 35 days (associated injuries), respectively. Results were excellent (n=9) or good (n=1) after pure dislocation. Results were excellent (n=15), good (n=7) or poor (n=1) in children with associated injuries. Accurate diagnosis, concentric stable reduction of the elbow as well as stable osteosynthesis of displaced fractures are associated with good results in children with acute posterior elbow dislocations.

  16. Bipolar dislocation of the forearm (floating forearm).

    PubMed

    Aşkar, Hüseyin; Ertürk, Cemil; Altay, Mehmet Akif; Akif Altay, Mehmet; Bilge, Ali

    2014-01-01

    Bipolar dislocation of the forearm (floating forearm) is an unusual injury and is therefore often overlooked. We report a 28-year-old male patient who presented at another center with a history of a fall while climbing a tree. The patient's left elbow was treated with closed reduction and immobilization with a long-arm cast brace due to elbow dislocation. However, the patient was admitted with pain and swelling of the wrist to our emergency department the following day. Physical and radiological examination revealed dorsal trans-scaphoid perilunate dislocation. A dorsal incision was performed for open reduction and internal fixation to provide wide surgical exposure. Concomitant occurrence of elbow dislocation and fracture-dislocation of the perilunate is infrequent. Therefore, physicians should be aware of possible additional injuries and current recommended treatment methods.

  17. 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.

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

    PubMed

    Bauer, Stefan; Dunne, Ben; Whitewood, Colin

    2012-12-12

    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.

  19. 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

  20. Traumatic posterior hip dislocation and ipsilateral distal femoral fracture in a 22-month-old child: a case report.

    PubMed

    Ciftdemir, Mert; Aydin, Deniz; Ozcan, Mert; Copuroglu, Cem

    2014-11-01

    Minor trauma may cause hip dislocation in young children because of physiologic hip joint laxity and the soft cartilaginous structure of the acetabulum. In this work, we report on a 22-month-old boy with right-sided traumatic posterior hip dislocation and ipsilateral distal femoral fracture because of an outdoor motor vehicle accident. The patient was treated with emergency closed reduction and one and a half hip spica under general anaesthesia. The femoral fracture and hip dislocation were healed smoothly without any complication. Traumatic hip dislocation is rare in children, which may occur after trivial trauma. Prognosis is better in younger patients with low-energy trauma and in cases treated early.

  1. Evolution, Interaction, and Intrinsic Properties of Dislocations in Intermetallics: Anisotropic 3D Dislocation Dynamics Approach

    SciTech Connect

    Chen, Qian

    2008-01-01

    The generation, motion, and interaction of dislocations play key roles during the plastic deformation process of crystalline solids. 3D Dislocation Dynamics has been employed as a mesoscale simulation algorithm to investigate the collective and cooperative behavior of dislocations. Most current research on 3D Dislocation Dynamics is based on the solutions available in the framework of classical isotropic elasticity. However, due to some degree of elastic anisotropy in almost all crystalline solids, it is very necessary to extend 3D Dislocation Dynamics into anisotropic elasticity. In this study, first, the details of efficient and accurate incorporation of the fully anisotropic elasticity into 3D discrete Dislocation Dynamics by numerically evaluating the derivatives of Green's functions are described. Then the intrinsic properties of perfect dislocations, including their stability, their core properties and disassociation characteristics, in newly discovered rare earth-based intermetallics and in conventional intermetallics are investigated, within the framework of fully anisotropic elasticity supplemented with the atomistic information obtained from the ab initio calculations. Moreover, the evolution and interaction of dislocations in these intermetallics as well as the role of solute segregation are presented by utilizing fully anisotropic 3D dislocation dynamics. The results from this work clearly indicate the role and the importance of elastic anisotropy on the evolution of dislocation microstructures, the overall ductility and the hardening behavior in these systems.

  2. Increasing preoperative dislocations and total time of dislocation affect surgical management of anterior shoulder instability

    PubMed Central

    Denard, Patrick J.; Dai, Xuesong; Burkhart, Stephen S.

    2015-01-01

    Purpose: Our purpose was to determine the relationship between number of preoperative shoulder dislocations and total dislocation time and the need to perform bone deficiency procedures at the time of primary anterior instability surgery. Our hypothesis was that need for bone deficiency procedures would increase with the total number and hours of dislocation. Materials and Methods: A retrospective review was performed of primary instability surgeries performed by a single surgeon. Patients with <25% glenoid bone loss were treated with an isolated arthroscopic Bankart repair. Those who also had an engaging Hill-Sachs lesion underwent arthroscopic Bankart repair with remplissage. Patients with >25% glenoid bone loss were treated with Latarjet reconstruction. Number of dislocations and total dislocation time were examined for their relationship with the treatment method. Results: Ten arthroscopic Bankart repairs, 13 arthroscopic Bankart plus remplissage procedures, and 9 Latarjet reconstructions were available for review. Total dislocations (P = 0.012) and total hours of dislocation (P = 0.019) increased from the Bankart, to the remplissage, to the Latarjet groups. Patients with a total dislocation time of 5 h or more were more likely to require a Latarjet reconstruction (P = 0.039). Patients with only 1 preoperative dislocation were treated with an isolated Bankart repair in 64% (7 of 11) of cases, whereas those with 2 or more dislocations required a bone loss procedure in 86% (18 of 21) of cases (P = 0.013). Conclusion: Increasing number of dislocations and total dislocation time are associated with the development of glenoid and humeral head bony lesions that alter surgical management of anterior shoulder instability. The necessity for the addition of a remplissage to an arthroscopic Bankart repair or the use of a Latarjet reconstruction increases with only 1 recurrent dislocation. Level of evidence: Level III, retrospective comparative study. PMID:25709237

  3. On Dislocation Glide in Planetary Interiors

    NASA Astrophysics Data System (ADS)

    Cordier, P.; Carrez, P.; Gouriet, K.; Kraych, A.; Ritterbex, S.

    2015-12-01

    The dynamics of hot planets depends strongly on how heat is transported to their surfaces through large scale convection flows. This is ultimately controlled by the rheology of high-pressure phases under extreme conditions. Whenever solid rocks are concerned, plastic flow results from the propagation of crystal defects (point defects, dislocations, grain boundaries). In this presentation we focus on the role of pressure on dislocation glide which is usually the most efficient strain-producing mechanism. Dislocation glide is assessed through multiscale numerical modeling. First, dislocations are modeled at the atomic scale based on first-principles calculations to incorporate the influence of pressure. Then the mobility law of dislocation at finite temperature is modeled by describing thermally-activated mechanisms for dislocation glide based on the kink-pair model. Then the flow stress at the grain scale is deduced either from application of the Orowan equation or by dislocation dynamics modeling. This approach is applied to wadsleyite, ringwoodite, bridgmanite and post-perovskite. Mechanical properties are either calculated at laboratory strain-rates to be compared with experiments when available or at mantle strain-rate to assess their efficiency under natural conditions.

  4. Thermodynamic forces in single crystals with dislocations

    NASA Astrophysics Data System (ADS)

    Van Goethem, Nicolas

    2014-06-01

    A simple model for the evolution of macroscopic dislocation regions in a single crystal is presented. This model relies on maximal dissipation principle within Kröner's geometric description of the dislocated crystal. Mathematical methods and tools from shape optimization theory provide equilibrium relations at the dislocation front, similarly to previous work achieved on damage modelling (J Comput Phys 33(16):5010-5044, 2011). The deformation state variable is the incompatible strain as related to the dislocation density tensor by a relation involving the Ricci curvature of the crystal underlying elastic metric. The time evolution of the model variables follows from a novel interpretation of the Einstein-Hilbert flow in terms of dislocation microstructure energy. This flow is interpreted as the dissipation of non-conservative dislocations, due to the climb mechanism, modelled by an average effect of mesoscopic dislocations moving normal to their glide planes by adding or removing points defects. The model equations are a fourth-order tensor parabolic equation involving the operator "incompatibility," here appearing as a tensorial counterpart of the scalar Laplacian. This work encompasses and generalizes results previously announced (C R Acad Sci Paris Ser I 349:923-927, 2011), with in addition a series of physical interpretations to give a meaning to the newly introduced concepts.

  5. Rehabilitation After Posterolateral Dislocation of the Elbow in a Collegiate Football Player: A Case Report

    PubMed Central

    Uhl, Tim L.; Gould, Michelle; Gieck, Joe H.

    2000-01-01

    Objective: To describe a functional rehabilitation program for a football player with a grade 2 posterolateral elbow dislocation to facilitate early return to competition. Background: Conservative management of a posterior dislocation of the elbow is common. The elbow is the second most frequently dislocated large joint in adults. Two common mechanisms of dislocation are hyperextension and posterolateral rotation. Prolonged immobilization can be detrimental to regaining full range of motion and function of the elbow, whereas early directed rehabilitation may lead to early return to normal function. Differential Diagnosis: Elbow dislocation with medial collateral ligament rupture, elbow subluxation, elbow dislocation with neurovascular compromise, or supracondylar fracture. Treatment: The athlete received immediate care of reduction and immobilization in a 90° posterior splint followed by a radiologic evaluation. Postreduction treatment included a short immobilization period and early initiation of protected active and resistive range-of-motion exercises. The athlete was able to return to full football activities in 3 weeks. He competed for the rest of the season with the elbow braced and taped, with no recurring incidents of instability. Uniqueness: The time to return to full participation was rapid. The medial collateral ligament was intact, as determined by magnetic resonance imaging. The athlete has since been followed for 2 football seasons and has not demonstrated any detrimental effects due to his early return. Conclusions: Early determination of the status of the medial collateral ligament through physical examination or imaging combined with early directed rehabilitation of a posterolateral elbow instability enabled this athlete to respond well. He regained pain-free full range of motion, strength, and function, allowing full participation in football at the Division I level with no recurring incidence of dislocation. Imagesp109-a PMID:16558601

  6. Distribution of distances between dislocations in different types of dislocation substructures in deformed Cu-Al alloys

    SciTech Connect

    Trishkina, L. Zboykova, N.; Koneva, N. Kozlov, E.; Cherkasova, T.

    2016-01-15

    The aim of the investigation was the determination of the statistic description of dislocation distribution in each dislocation substructures component forming after different deformation degrees in the Cu-Al alloys. The dislocation structures were investigated by the transmission diffraction electron microscopy method. In the work the statistic description of distance distribution between the dislocations, dislocation barriers and dislocation tangles in the deformed Cu-Al alloys with different concentration of Al and test temperature at the grain size of 100 µm was carried out. It was established that the above parameters influence the dislocation distribution in different types of the dislocation substructures (DSS): dislocation chaos, dislocation networks without disorientation, nondisoriented and disoriented cells, in the walls and inside the cells. The distributions of the distances between dislocations in the investigated alloys for each DSS type formed at certain deformation degrees and various test temperatures were plotted.

  7. Monteggia fracture-dislocations: A Historical Review

    PubMed Central

    Rehim, Shady A.; Maynard, Mallory A.; Sebastin, Sandeep J.; Chung, Kevin C.

    2014-01-01

    The eponym Monteggia fracture-dislocation originally referred to a fracture of the shaft of the ulna accompanied by anterior dislocation of the radial head that was described by Giovanni Battista Monteggia of Italy in 1814. Subsequently, a further classification system based on the direction of the radial head dislocation and associated fractures of the radius and ulna was proposed by Jose Luis Bado of Uruguay in 1958. This article investigates the evolution of treatment, classification, and outcomes of the Monteggia injury and sheds light on the lives and contributions of Monteggia and Bado. PMID:24792923

  8. [Conservative treatment of congenital patellar dislocation].

    PubMed

    Zajonz, D; Schumann, E; Wojan, M; Moche, M; Heyde, C-E

    2017-02-01

    This article presents the rare case of a boy who was born in our hospital with valgus deformity and external rotation of the right lower leg because of congenital patellar dislocation. In the case presented a stable repositioning of the patella could be achieved by redressment with a plaster cast and leg brace. During a 4-year follow-up there were no tendencies towards dislocation during the clinical examination and no dislocation events were documented. In selected cases an attempt at conservative repositioning and retention treatment appears to be worthwhile before surgical treatment is indicated.

  9. Distal radioulnar joint injuries

    PubMed Central

    Thomas, Binu P; Sreekanth, Raveendran

    2012-01-01

    Distal radioulnar joint is a trochoid joint relatively new in evolution. Along with proximal radioulnar joint, forearm bones and interosseous membrane, it allows pronosupination and load transmission across the wrist. Injuries around distal radioulnar joint are not uncommon, and are usually associated with distal radius fractures,fractures of the ulnar styloid and with the eponymous Galeazzi or Essex_Lopresti fractures. The injury can be purely involving the soft tissue especially the triangular fibrocartilage or the radioulnar ligaments. The patients usually present with ulnar sided wrist pain, features of instability, or restriction of rotation. Difficulty in carrying loads in the hand is a major constraint for these patients. Thorough clinical examination to localize point of tenderness and appropriate provocative tests help in diagnosis. Radiology and MRI are extremely useful, while arthroscopy is the gold standard for evaluation. The treatment protocols are continuously evolving and range from conservative, arthroscopic to open surgical methods. Isolated dislocation are uncommon. Basal fractures of the ulnar styloid tend to make the joint unstable and may require operative intervention. Chronic instability requires reconstruction of the stabilizing ligaments to avoid onset of arthritis. Prosthetic replacement in arthritis is gaining acceptance in the management of arthritis. PMID:23162140

  10. "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.

  11. Traumatic bilateral knee dislocations, unilateral hip dislocation, and contralateral humeral amputation: a case report.

    PubMed

    Voos, James E; Heyworth, Benton E; Piasecki, Dana P; Henn, R Frank; MacGillivray, John D

    2009-02-01

    Bilateral traumatic knee dislocations are a rarity. We report a case of bilateral traumatic knee dislocations with concomitant right hip dislocation and complete traumatic amputation of the left, nondominant upper extremity at the level of the proximal one-third of the humerus. Angiograms revealed no evidence of popliteal artery injury. Orthopedic treatment consisted of immediate reduction of the dislocations and urgent revision amputation of the upper extremity. Staged, bilateral knee ligamentous reconstructions were performed on hospital days 24 and 29, respectively. Despite this constellation of devastating injuries, the patient had a satisfactory outcome. In patients with high-energy hip or knee dislocations, the bilateral hips and knees should be carefully examined to check for associated fractures and/or dislocations.

  12. “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

  13. Fundamentals in generalized elasticity and dislocation theory of quasicrystals: Green tensor, dislocation key-formulas and dislocation loops

    NASA Astrophysics Data System (ADS)

    Lazar, Markus; Agiasofitou, Eleni

    2014-12-01

    The present work provides fundamental quantities in generalized elasticity and dislocation theory of quasicrystals. In a clear and straightforward manner, the three-dimensional Green tensor of generalized elasticity theory and the extended displacement vector for an arbitrary extended force are derived. Next, in the framework of dislocation theory of quasicrystals, the solutions of the field equations for the extended displacement vector and the extended elastic distortion tensor are given; that is, the generalized Burgers equation for arbitrary sources and the generalized Mura-Willis formula, respectively. Moreover, important quantities of the theory of dislocations as the Eshelby stress tensor, Peach-Koehler force, stress function tensor and the interaction energy are derived for general dislocations. The application to dislocation loops gives rise to the generalized Burgers equation, where the displacement vector can be written as a sum of a line integral plus a purely geometric part. Finally, using the Green tensor, all other dislocation key-formulas for loops, known from the theory of anisotropic elasticity, like the Peach-Koehler stress formula, Mura-Willis equation, Volterra equation, stress function tensor and the interaction energy are derived for quasicrystals.

  14. Ipsilateral open anterior hip dislocation and open posterior elbow dislocation in an adult.

    PubMed

    Kumar, Sunil; Rathi, Akhilesh; Sehrawat, Sunil; Gupta, Vikas; Talwar, Jatin; Arora, Sumit

    2014-01-01

    Open anterior dislocation of the hip is a very rare injury, especially in adults. It is a hyperabduction, external rotation and extension injury. Its combination with open posterior dislocation of the elbow has not been described in English language-based medical literature. Primary resuscitation, debridement, urgent reduction of dislocation, and adequate antibiotic support resulted in good clinical outcome in our patient. At 18 months follow-up, no signs of avascular necrosis of the femoral head or infection were observed.

  15. Anisotropic Dislocation Line Energy and Crack Tip Dislocation Nucleation in (alpha)RDX

    DTIC Science & Technology

    2013-11-01

    November 2013 Anisotropic Dislocation Line Energy and Crack Tip Dislocation Nucleation in αRDX Lynn B. Munday and Jaroslaw Knap Computational ...public release; distribution is unlimited. 13. SUPPLEMENTARY NOTES 14. ABSTRACT This work reports on the algorithms used to determine the...anisotropic and isotropic elastic properties of dislocations and their nucleation from a crack tip. The appendix contains a numerical implementation of these

  16. Bilateral Galeazzi fracture-dislocations: a case report of early rehabilitation.

    PubMed

    Komura, Shingo; Nonomura, Hidehiko; Satake, Takashi; Yokoi, Tatsuo

    2012-08-01

    A 24-year-old man had bilateral Galeazzi fracture-dislocations due to a motorcycle accident. The right radius fracture was a simple fracture and was fixed with a limited contact dynamic compression plate. The left radius fracture was a comminuted fracture and was fixed with a long locking compression plate in the bridging plate fashion while maintaining reduction with a temporary external fixator. Postoperative computed tomography under passive rotation of both forearms showed acceptable congruency of the distal radioulnar joints, and early rehabilitation of forearm rotation was started at 2 weeks after the operation. At 13-month follow-up, bone union of both fractures was achieved, and forearm motion was almost restored to normal. Moreover, no subluxation or dislocation of either distal radioulnar joint was observed.

  17. 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

  18. Automated identification and indexing of dislocations in crystal interfaces

    SciTech Connect

    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 and also identifies dislocation junctions.

  19. Quenched pinning and collective dislocation dynamics

    PubMed Central

    Ovaska, Markus; Laurson, Lasse; Alava, Mikko J.

    2015-01-01

    Several experiments show that crystalline solids deform in a bursty and intermittent fashion. Power-law distributed strain bursts in compression experiments of micron-sized samples, and acoustic emission energies from larger-scale specimens, are the key signatures of the underlying critical-like collective dislocation dynamics - a phenomenon that has also been seen in discrete dislocation dynamics (DDD) simulations. Here we show, by performing large-scale two-dimensional DDD simulations, that the character of the dislocation avalanche dynamics changes upon addition of sufficiently strong randomly distributed quenched pinning centres, present e.g. in many alloys as immobile solute atoms. For intermediate pinning strength, our results adhere to the scaling picture of depinning transitions, in contrast to pure systems where dislocation jamming dominates the avalanche dynamics. Still stronger disorder quenches the critical behaviour entirely. PMID:26024505

  20. 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

  1. Dislocation Glasses: Aging during Relaxation and Coarsening

    SciTech Connect

    Bako, B.; Groma, I.; Gyoergyi, G.; Zimanyi, G. T.

    2007-02-16

    The dynamics of dislocations is reported to exhibit a range of glassy properties. We study numerically various versions of 2D edge dislocation systems, in the absence of externally applied stress. Two types of glassy behavior are identified (i) dislocations gliding along randomly placed, but fixed, axes exhibit relaxation to their spatially disordered stable state; (ii) if both climb and annihilation are allowed, irregular cellular structures can form on a growing length scale before all dislocations annihilate. In all cases both the correlation function and the diffusion coefficient are found to exhibit aging. Relaxation in case (i) is a slow power law, furthermore, in the transient process (ii) the dynamical exponent z{approx_equal}6, i.e., the cellular structure coarsens relatively slowly.

  2. Hydrogenated vacancies lock dislocations in aluminium

    NASA Astrophysics Data System (ADS)

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

    2016-11-01

    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.

  3. Investigation of the Dynamics of a Screw Dislocation in Copper

    NASA Astrophysics Data System (ADS)

    Kolupaeva, S. N.; Petelina, Yu. P.; Polosukhin, K. A.; Petelin, A. E.

    2015-08-01

    A modification of the mathematical model of forming the crystallographic shear band is proposed in which the strength of elastic interaction between all dislocations of the forming dislocation pileups is taken into account in addition to the Peach-Keller force; lattice, impurity, and dislocation friction; linear tension; viscous braking; and intensity of generation of point defects behind kinks. The model is used to investigate the influence of the dislocation density on the time characteristics of the formation of dislocation loops in copper.

  4. Total hip arthroplasty in paralytic dislocation from poliomyelitis.

    PubMed

    Laguna, Rafael; Barrientos, Jesús

    2008-02-01

    This article presents a case of a patient with degenerative hip disease in paralytic dislocation by poliomyelitis. Poliomyelitis is an acute infection disease caused by a group of neurotrophic viruses, which has a special affinity by the anterior horns cells of the spinal cord and for certain motor nuclei of the brain stem. Paralysis is a flaccid type and characteristically paralysis is asymmetrical. It is said that the joints of the affected limb by poliomyelitis are protected from the development of osteoarthritis. Hip dislocation in poliomyelitis is an acquired deformity caused by flaccid paralysis and the resulting muscular imbalance. In young children, when the gluteus maximus and medius muscles are paralyzed and the hip flexors and adductors are of normal strength, eventual luxation of the hip is almost inevitable. Hip osteoarthritis in a limb with poliomyelitis is an unusual entity because these limbs do not support excessive loads. In patients who present with the residual effects of poliomyelitis including degenerative disease and hip dysplastic, surgery is one of the most difficult challenges faced by reconstructive surgeons. In such cases, surgeons should attempt to optimize the component position and choice, surgical approach, and soft tissue tensioning because stability of the prosthesis can be problematic.

  5. 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

  6. Radiological assessment of irreducible posterolateral knee subluxation after dislocation due to interposition of the vastus medialis: a case report.

    PubMed

    Paulin, Emilie; Boudabbous, Sana; Nicodème, Jean-Damien; Arditi, Daniel; Becker, Christoph

    2015-06-01

    Knee dislocation is a serious and relatively uncommon traumatism that every emergency room is supposed to diagnose and treat rapidly. Most of the time these dislocations reduce spontaneously or with closed reduction. If a subluxation persists, an incarceration of soft tissue in the joint must be suspected. Irreducible knee subluxations after dislocation are rare entities better described in the orthopaedic than in the radiological literature. However, the initial radiological assessment is an important tool to obtain the correct diagnosis, to detect neurovascular complications, and to plan the most suitable treatment. In cases of delayed diagnosis, the functional prognosis of the joint and even the limb may be seriously compromised primarily because of vascular lesions. Thereby, vascular imaging is essential in cases of dislocation of the knee, and we will discuss the role of angiography and the more recent use of computed tomography angiography or magnetic resonance angiography. Our patient presented with an irreducible knee subluxation due to interposition of the vastus medialis, and we will review the classical clinical presentation and 'do not miss' imaging findings on conventional radiography, computed tomography angiography, and magnetic resonance imaging. Finally, we will also report the classical imaging pathway indicated in knee dislocation, with a special emphasis on the irreducible form.

  7. Quantum dynamics of a single dislocation

    NASA Astrophysics Data System (ADS)

    de Gennes, Pierre-Gilles

    We discuss the zero temperature motions of an edge dislocation in a quantum solid (e.g., He4). If the dislocation has one kink (equal in length to its Burgers vector b) the kink has a creation energy U and can move along the line with a certain transfer integral t. When t and U are of comparable magnitude, two opposite kinks can form an extended bound state, with a size l. The overall shape of the dislocation in the ground state is then associated with a random walk of persistence length l (along the line) and hop sizes b. We also discuss the motions of kinks under an applied shear stress σ: the glide velocity is proportional to exp(-σ*/σ), where σ* is a characteristic stress, controlled by tunneling processes. Mouvements quantiques d'une dislocation. On analyse le mouvement à température nulle d'une dislocation coin dans un solide quantique (He4). La dislocation peut avoir un cran (d'énergie U) dans son plan de glissement. Le cran peut avancer ou reculer le long de la dislocation par effet tunnel, avec une certaine intégrale de transfert t. Deux crans de signe opposé peuvent former un état lié. En présence d'une contrainte extérieure σ, la ligne doit avancer avec une vitesse ~exp(-σ*/σ) où σ* est une contrainte seuil, contrôlée par l'effet tunnel.

  8. Continuum Theory of Dislocations: Cell Structure Formation

    NASA Astrophysics Data System (ADS)

    Limkumnerd, Surachate; Sethna, James P.

    2005-03-01

    Line-like topological defects inside metals are called dislocations. These dislocations in late stages of hardening form patterns called cell structures. We are developing a mesoscale theory for the formation of cell structures that systematically derives the order parameter fields and evolution laws from the conserved topological Burgers vector density or the Nye dislocation tensor. (In classical plasticity theories, describing scales large compared to these cells, one normally bypasses the complicated motions of the dislocations by supplying yield surface and plastic hardening function in order to determine the evolution of state variables.) Using Landau approach and a closure approximation, an evolution equation for the dislocation density tensor is obtained by employing simple symmetry arguments and the constraint that the elastic energy must decrease with time at fixed stress. The evolution laws lead to singularity formation at finite times, which we expect will be related to the formation of cell walls. Implementation of finite difference simulations using the upwind scheme and the results in one and higher dimensions will be discussed.

  9. Chiral anomaly in Dirac semimetals due to dislocations

    NASA Astrophysics Data System (ADS)

    Chernodub, M. N.; Zubkov, M. A.

    2017-03-01

    The dislocation in Dirac semimetal carries an emergent magnetic flux parallel to the dislocation axis. We show that due to the emergent magnetic field, the dislocation accommodates a single fermion massless mode of the corresponding low-energy one-particle Hamiltonian. The mode is propagating along the dislocation with its spin directed parallel to the dislocation axis. In agreement with the chiral anomaly observed in Dirac semimetals, an external electric field results in the spectral flow of the one-particle Hamiltonian, in pumping of the fermionic quasiparticles out from vacuum, and in creating a nonzero axial (chiral) charge in the vicinity of the dislocation.

  10. High dislocation density of tin induced by electric current

    SciTech Connect

    Liao, Yi-Han; Liang, Chien-Lung; Lin, Kwang-Lung; Wu, Albert T.

    2015-12-15

    A dislocation density of as high as 10{sup 17} /m{sup 2} in a tin strip, as revealed by high resolution transmission electron microscope, was induced by current stressing at 6.5 x 10{sup 3} A/ cm{sup 2}. The dislocations exist in terms of dislocation line, dislocation loop, and dislocation aggregates. Electron Backscattered Diffraction images reflect that the high dislocation density induced the formation of low deflection angle subgrains, high deflection angle Widmanstätten grains, and recrystallization. The recrystallization gave rise to grain refining.

  11. Congenital Deficiency of Distal Ulna and Dislocation of the Radial Head Treated by Single Bone Forearm Procedure

    PubMed Central

    Dutta, Anshuman; Sipani, Arun Kumar; Daolagupu, Arup Kumar

    2014-01-01

    Congenital deficiency of part of distal ulna affecting the distal radio-ulnar joint is a rare disorder. It is even rarer to find the association of proximal radio-ulnar joint dislocation along with distal ulnar deficiency. This type of congenital forearm anomaly is difficult to treat. Conversion to a single bone forearm in the expense of pronation-supination movement is a viable option. By doing so the elbow and wrist can be stabilized; however movement is possible in only one plane. We are describing here a girl of 8 years having proximal radio-ulnar joint dislocation along with deficiency of distal ulna treated by converting into a single bone forearm. PMID:25254127

  12. OPEN REDUCTION OF HIP DISLOCATION IN PATIENTS WITH ARTHROGRYPOSIS MULTIPLEX CONGENITA – AN ANTEROMEDIAL APPROACH

    PubMed Central

    Rocha, Luis Eduardo Munhoz da; Nishimori, Fábio Koiti; Figueiredo, Daniel Carvalho de; Grimm, Dulce Helena; Cunha, Luiz Antonio Munhoz da

    2015-01-01

    To evaluate the results from surgical treatment of hip dislocation through the anteromedial approach, in patients with arthrogryposis multiplex congenita (AMC). Methods: The medical files and radiographs of seven children with AMC who presented hip dislocation (total of 10 dislocated hips) were retrospectively reviewed. Pre and postoperative joint mobility was evaluated by summing the joint range of motion in flexion and abduction. The acetabular angle and height of the femoral neck before the operation, and the continuity of the Shenton arc, Sharp angle and center-edge (CE) angle after the operation, were evaluated radiographically. When avascular necrosis was identified, it was classified in accordance with Ogden and Bucholz. Results: The mean age of the children at the time of the surgery was 5.5 months (range: 3 to 11 months). The mean duration of follow-up for the patients was 9.5 years (range: 2 to 13 years). The mean amplitude of the sum of the joint range of motion in flexion and abduction in the preoperative examination was 108° (range: 70° to 155°) and postoperatively, it was 125° (range: 75° to 175°). In the last evaluation, eight hips were found to be centered and two were subluxated. Two hips had been subjected to Salter iliac osteotomy. Two hips (20%) had presented significant signs of Ogden type IV avascular necrosis. Eight hips had good results while two were fair. Conclusion: We consider that the anteromedial approach is a good option for treating hip dislocation in very young patients with arthrogryposis multiplex congenita. PMID:27022586

  13. Successful Conservative Management of a Dislocated IUD

    PubMed Central

    Inal, Hasan Ali; Ozturk Inal, Zeynep; Alkan, Ender

    2015-01-01

    Background. Intrauterine contraceptive devices (IUDs) are widely utilized all over the world owing to their low cost and high efficacy. Uterine perforation is a rare complication that may occur at IUD insertion resulting in extrauterine location of the IUD. Traditionally, surgical removal of dislocated IUDs has been recommended. Case. A 68-year-old patient who had an IUD (Lippes loop) inserted 32 years ago and whose routine examination incidentally revealed a dislocated IUD in the abdominal cavity. The patient remained asymptomatic during three years of follow-up and the IUD was left in place. Conclusion. Asymptomatic patients, whose vaginal examinations and ultrasonography or X-ray results reveal a dislocated IUD, may benefit from conservative management. PMID:25861494

  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. Chronic Elbow Dislocation: Evaluation and Management.

    PubMed

    Donohue, Kenneth W; Mehlhoff, Thomas L

    2016-07-01

    Chronic elbow dislocation is defined as a dislocation that has remained unreduced for >2 weeks. The soft-tissue and skeletal changes that develop during this time usually prevent successful closed reduction. These changes include the development of extensive intra-articular fibrotic tissue, as well as contracture of the triceps, collateral ligaments, and elbow capsule. Ulnar nerve involvement and associated fractures may also be present. Because treatment of chronic elbow dislocation is challenging, a stepwise approach is used in the evaluation and management of this condition. No large series of data are available to guide treatment. Most patients are treated on the basis of the surgeon's anecdotal experience. Treatment typically involves open reduction, often with the use of hinged external fixators. The role of triceps lengthening or primary collateral ligament reconstruction remains a topic of debate.

  16. ACS: ALMA Common Software

    NASA Astrophysics Data System (ADS)

    Chiozzi, Gianluca; Šekoranja, Matej

    2013-02-01

    ALMA Common Software (ACS) provides a software infrastructure common to all ALMA partners and consists of a documented collection of common patterns and components which implement those patterns. The heart of ACS is based on a distributed Component-Container model, with ACS Components implemented as CORBA objects in any of the supported programming languages. ACS provides common CORBA-based services such as logging, error and alarm management, configuration database and lifecycle management. Although designed for ALMA, ACS can and is being used in other control systems and distributed software projects, since it implements proven design patterns using state of the art, reliable technology. It also allows, through the use of well-known standard constructs and components, that other team members whom are not authors of ACS easily understand the architecture of software modules, making maintenance affordable even on a very large project.

  17. Open anterior dislocation of the hip in an adult: a case report and review of literature.

    PubMed

    de Oliveira, Anderson Luiz; Machado, Eduardo Gomes

    2014-01-01

    Open anterior hip dislocation is a rare condition and results from high-energy trauma. Ten cases of open anterior dislocation have been described in the literature so far. Its rarity is due to the inherent stability of the joint, its deep position in the pelvis, with strong ligaments and bulky muscles around the articulation. Several factors influence the prognosis, such as the degree of compounding, the associated soft tissue injuries, the age of the patient and, mainly, the delay in reduction. The main complications are: arthrosis of the hip, with incidence of 50% of cases, when associated with fractures of the femoral head; and osteonecrosis of the femoral head, with incidence between 1.7 and 40% (in closed anterior dislocation). Because of the rarity and the potential disability of this lesion, we report a case in a 46-year-old man, involved in an automobile accident. The hip was reduced (anterior superior dislocation) in the first three hours of the trauma. The patient was kept non-weight bearing until sixth week, with complete weight bearing after 10th week. After one year follow-up, the functional result was poor (Harris Hip Score: 52), probably because of the associated labral tear, but without signs of osteonecrosis of the femoral head in magnetic resonance imaging.

  18. Elbow fracture-dislocation combined with Galeazzi fracture in adult: A case report and literature review

    PubMed Central

    Asadollahi, Saeed; Shepherd, David; Hau, Raphael C.

    2013-01-01

    INTRODUCTION Galeazzi fracture associated with ipsilateral posterior elbow dislocation and radial head fracture is a rare pattern of injury. Few reports exist that describes this injury pattern and its treatment. We describe a case report of simultaneous occurrence of Galeazzi fracture and ipsilateral dislocation of elbow. PRESENTATION OF CASE A 58 year-old female presented with Galeazzi fracture and posterior elbow dislocation associated with radial head fracture of left upper extremity. This was managed with closed reduction of the elbow, open reduction and internal fixation of the radial shaft fracture and K-wire stabilisation of the unstable distal radioulnar joint. Prophylactic fasciotomy was performed. At 10 months follow-up, the outcome was favourable with the American shoulder and elbow surgeon score of 92 and the disabilities of the arm, shoulder and hand score of 18. DISCUSSION The presumed mechanism of the injury was a forceful axial loading of a hyperpronated forearm and extended elbow. Our literature review shows that this pattern of injury occurs as a result of high energy trauma in young individuals, and successful outcome can be achieved by addressing each component of this complex injury individually. CONCLUSION Simultaneous occurrence of elbow dislocation and Galeazzi fracture seems to be the result of extreme axial force and unique position of upper extremity at the time of impact. Individualised approach to each component of this injury can result in favourable outcome. PMID:23726112

  19. High-temperature discrete dislocation plasticity

    NASA Astrophysics Data System (ADS)

    Keralavarma, S. M.; Benzerga, A. A.

    2015-09-01

    A framework for solving problems of dislocation-mediated plasticity coupled with point-defect diffusion is presented. The dislocations are modeled as line singularities embedded in a linear elastic medium while the point defects are represented by a concentration field as in continuum diffusion theory. Plastic flow arises due to the collective motion of a large number of dislocations. Both conservative (glide) and nonconservative (diffusion-mediated climb) motions are accounted for. Time scale separation is contingent upon the existence of quasi-equilibrium dislocation configurations. A variational principle is used to derive the coupled governing equations for point-defect diffusion and dislocation climb. Superposition is used to obtain the mechanical fields in terms of the infinite-medium discrete dislocation fields and an image field that enforces the boundary conditions while the point-defect concentration is obtained by solving the stress-dependent diffusion equations on the same finite-element grid. Core-level boundary conditions for the concentration field are avoided by invoking an approximate, yet robust kinetic law. Aspects of the formulation are general but its implementation in a simple plane strain model enables the modeling of high-temperature phenomena such as creep, recovery and relaxation in crystalline materials. With emphasis laid on lattice vacancies, the creep response of planar single crystals in simple tension emerges as a natural outcome in the simulations. A large number of boundary-value problem solutions are obtained which depict transitions from diffusional to power-law creep, in keeping with long-standing phenomenological theories of creep. In addition, some unique experimental aspects of creep in small scale specimens are also reproduced in the simulations.

  20. Interaction of dislocations with carbon-decorated dislocation loops in bcc Fe: an atomistic study.

    PubMed

    Terentyev, Dmitry; Anento, Napoleón; Serra, Anna

    2012-11-14

    Properties of ferritic Fe-based alloys are highly sensitive to the carbon content dissolved in the matrix because interstitial carbon is known to strongly interact with lattice point defects and dislocations. As a result, the accumulation of radiation defects and its impact on the change of mechanical properties is also affected by the presence of dissolved interstitial carbon. This work contributes to an understanding of how interstitial carbon atoms influence the properties of small dislocation loops, which form directly in collision cascades upon neutron or ion irradiation and are 'invisible' to (i.e. undetectable by) standard experimental techniques applied to reveal nano-structural damage in metals. We have carried out MD simulations to investigate how the trapping of 1/2 inner product 111 dislocation loops at thermally stable carbon-vacancy complexes, known to form under irradiation, affects the interaction of these dislocation loops with dislocations in bcc Fe. We have considered loops of size 1 and 3.5 nm, which represent experimentally invisible and visible defects, respectively. The obtained results point at the strong suppression of the drag of carbon-decorated loops by dislocations. In the case of direct interaction between dislocation and carbon-decorated loops, invisible loops are found to act as obstacles whose strength is at least twice as high compared to that of undecorated ones. Additional strengthening due to the carbon decoration on the visible loops was also regularly registered. The reasons for the additional strengthening have been rationalized and discussed. It is demonstrated that carbon decoration/segregation at dislocation loops affects not only accumulation of radiation damage under prolonged irradiation but also alters the post-irradiation plastic deformation mechanisms. For the first time, we provide evidence that undetectable dislocation loops decorated by carbon do contribute to the radiation hardening.

  1. Geometry of dislocated de Broglie waves

    SciTech Connect

    Holland, P.R.

    1987-04-01

    The geometrical structures implicit in the de Broglie waves associated with a relativistic charged scalar quantum mechanical particle in an external field are analyzed by employing the ray concept of the causal interpretation. It is shown how an osculating Finslerian metric tensor, a torsion tensor, and a tetrad field define respectively the strain, the dislocation density, and the Burgers vector in the natural state of the wave, which is a non-Riemannian space of distant parallelism. A quantum torque determined by the quantum potential is introduced and the example of a screw dislocated wave is discussed.

  2. Mesoscale modeling of dislocations in molecular crystals

    NASA Astrophysics Data System (ADS)

    Lei, Lei; Koslowski, Marisol

    2011-02-01

    Understanding the inelastic deformation of molecular crystals is of fundamental importance to the modeling of the processing of drugs in the pharmaceutical industry as well as to the initiation of detonation in high energy density materials. In this work, we present dislocation dynamics simulations of the deformation of two molecular crystals of interest in the pharmaceutical industry, sucrose and paracetamol. The simulations calculate the yield stress of sucrose and paracetamol in good agreement with experimental observation and predict the anisotropy in the mechanical response observed in these materials. Our results show that dislocation dynamics is an effective tool to study plastic deformation in molecular crystals.

  3. Irreducible posterolateral elbow dislocation: a rare injury.

    PubMed

    Fenelon, Christopher; Zafar, Muhammed M; Sheridan, Gerard Anthony; Kearns, Stephen

    2016-12-30

    Posterolateral dislocation of the elbow is an injury commonly treated in the emergency department by closed reduction. Very rarely it can be irreducible and require open reduction. Only four cases of irreducible posterolateral elbow dislocation have been described in the literature over the past 50 years. We report the case of a 20-year-old man who sustained such an injury. Open reduction was performed and revealed the radial head protruding or 'buttonholing' through the lateral collateral ligament complex. This case highlights that continued closed reduction of the elbow should not be attempted, as a mechanical block to reduction can occur making reduction impossible.

  4. Rotator Cuff Tear Consequent to Glenohumeral Dislocation.

    PubMed

    Gilotra, Mohit N; Christian, Matthew W; Lovering, Richard M

    2016-08-01

    The patient was a 21-year-old collegiate running back who was tackled during a football game and sustained a posterior glenohumeral dislocation. He was referred to an orthopaedist and presented 3 weeks after the injury, and, following examination, further imaging was ordered by the orthopaedist due to rotator cuff weakness. Magnetic resonance imaging showed a complete tear of the supraspinatus and infraspinatus, as well as a posterior Bankart lesion, a subscapularis tear, and a dislocation of the biceps long head tendon into the reverse Hill-Sachs lesion. J Orthop Sports Phys Ther 2016;46(8):708. doi:10.2519/jospt.2016.0413.

  5. New Criterion for Evaluating the Peak Shear Strength of Rock Joints Under Different Contact States

    NASA Astrophysics Data System (ADS)

    Tang, Zhi Cheng; Wong, Louis Ngai Yuen

    2016-04-01

    In practice, the peak shear strength of rock joints is not dictated only by the surface roughness, but also the degree of matching between the joint surfaces. The latter is due to alteration/dislocation caused by external factors, such as the vibration due to nearby blasting, excavation or earthquake. In the present study, the peak shear strengths of rock joints under different contact states are investigated by direct shear test using artificial rock joints. The rock joints under different contact states are modeled by imposing varying magnitude of horizontal dislocation along the shear direction between the upper and lower rock blocks. The peak shear strength was found to decrease with increasing dislocation. A new empirical shear strength criterion is put forward to capture the peak shear strength of un-matching rock joints as an extension of a previously published peak shear strength criterion for matching rock joints by the first author and his co-workers. In the present proposed criterion, a new joint contact state coefficient, which is a function of the normalized dislocation and the quantified three-dimensional roughness metric of joint surface, is proposed. The good agreement between calculated values and test results indicates that the proposed criterion is capable of estimating the peak shear strength of rock joints under different contact states. The proposed criterion is expressed in a quantitative way and the required parameters can be easily determined in the laboratory.

  6. Changes in the Burgers Vector of Perfect Dislocation Loops without Contact with the External Dislocations

    SciTech Connect

    Arakawa, K.; Hatanaka, M.; Mori, H.; Kuramoto, E.; Ono, K.

    2006-03-31

    We report the observations of a new type of changing process in the Burgers vector of dislocations by in situ transmission electron microscopy. Small interstitial-type perfect dislocation loops in bcc iron with diameters less than approximately 50 nm are transformed from a 1/2<111> loop to another 1/2<111> one or an energetically unfavorable <100> one; furthermore, a <100> loop is transformed to a 1/2<111> one. These transformations occurred on high-energy electron irradiation or simple heating without contact with external dislocations. The origin of these phenomena is discussed.

  7. Temporomandibular joint disorder and inner ear pruritus: resolution by eminectomy.

    PubMed

    Pentyala, Sahana; Mysore, Pooja; Moller, Daryn; Pentyala, Srinivas; Kardovich, Richard; Martino, Andrew; Proothi, Michael

    2014-09-01

    Recurrent dislocation of the temporomandibular joint (TMJ) disk is caused by many factors. Dislocation can result in an acute or chronic closed lock condition. Temporomandibular joint dysfunction is often presented with otalgia symptoms. Other aural symptoms such as deafness, tinnitus, pressure/blockage, and vertigo are also commonly presented together with TMJ dysfunction (Clin Otolaryngol Allied Sci. 1980;5:23-36). However, pruritus associated with TMJ dysfunction in the inner ear has never been reported in the literature. We report a case history of TMJ dysfunction and associated inner ear pruritus, which are both resolved by eminectomy.

  8. Effect of dislocations on helium retention in deformed pure iron

    NASA Astrophysics Data System (ADS)

    Gong, Y. H.; Cao, X. Z.; Jin, S. X.; Lu, E. Y.; Hu, Y. C.; Zhu, T.; Kuang, P.; Xu, Q.; Wang, B. Y.

    2016-12-01

    The effects of dislocations created by deformation on helium retention in pure iron, including the helium atoms diffusion along the dislocation line and desorption from dislocation trapping sites, were investigated. The dislocation defect was introduced in specimens by cold-rolling, and then 5 keV helium ions were implanted into the deformed specimens. Slow positron beam technology and thermal desorption spectroscopy were used to investigate the evolution of dislocation defects and the desorption behavior of helium atoms under influence of dislocation. The behaviors of S-E, W-E and S-W plots indicate clearly that lots of helium atoms remain in the deformed specimen and helium atoms combining with dislocation change the distribution of electron density. The helium desorption plot indicates that dislocation accelerates helium desorption at 293 K-600 K and facilitates helium dissociation from HenVm (n/m = 1.8) cluster.

  9. Dislocation of the lens: a complication after cyclocryotherapy.

    PubMed

    Sony, Parul; Sharma, Namrata; Pangtey, Mayank S

    2002-12-01

    An unusual complication is reported of a case of complete dislocation of the lens after cyclocryotherapy in a patient with neovascular glaucoma. To the best of the authors' knowledge, no case of lens dislocation following cyclocryotherapy has previously been reported.

  10. A dislocation density based constitutive model for cyclic deformation

    SciTech Connect

    Estrin, Y.; Braasch, H.; Brechet, Y.

    1996-10-01

    A new constitutive model describing material response to cyclic loading is presented. The model includes dislocation densities as internal variables characterizing the microstructural state of the material. In the formulation of the constitutive equations, the dislocation density evolution resulting from interactions between dislocations in channel-like dislocation patterns is considered. The capabilities of the model are demonstrated for INCONEL 738 LC and Alloy 800H.

  11. Dislocations in magnetohydrodynamic waves in a stellar atmosphere.

    PubMed

    López Ariste, A; Collados, M; Khomenko, E

    2013-08-23

    We describe the presence of wave front dislocations in magnetohydrodynamic waves in stratified stellar atmospheres. Scalar dislocations such as edges and vortices can appear in Alfvén waves, as well as in general magnetoacoustic waves. We detect those dislocations in observations of magnetohydrodynamic waves in sunspots in the solar chromosphere. Through the measured charge of all the dislocations observed, we can give for the first time estimates of the modal contribution in the waves propagating along magnetic fields in solar sunspots.

  12. 75 FR 64727 - Joint and Several Liability Reallocation Agreement

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-10-20

    ... RIN 3052-AC64 Joint and Several Liability Reallocation Agreement AGENCY: Farm Credit Administration. ACTION: Notice of approval of the draft joint and several liability reallocation agreement. SUMMARY: The Farm Credit Administration (FCA or we) is announcing that it has given approval of a Joint and...

  13. Anterior knee dislocation with ipsilateral open tibial shaft fracture: a 5-year clinical follow-up of a professional athlete.

    PubMed

    Aydın, Adem; Atmaca, Halil; Müezzinoğlu, Ümit Sefa

    2013-08-01

    Traumatic dislocation of the knee joint is an uncommon complex, multiple ligamentous injury resulting from a high-energy trauma. Significant lack of functions can be seen because of both early and late complications of these injuries such as popliteal artery disruption, peroneal nerve injury, persistent instability and posttraumatic arthritis. Therefore, the emergency surgery is necessary due to possibility of neurovascular compromise and limb loss. Controversies over operative versus closed immobilization of traumatic complex, multiple ligamentous knee injury are still debated. We report a case of traumatic anterior dislocation of the right knee with an ipsilateral tibial shaft fracture in association with right popliteal artery occlusion of a professional athlete who was returned to his sports activity by surgical treated tibia fracture and conservative treatment of the knee dislocation.

  14. Dislocation substructure in fatigued duplex stainless steel

    SciTech Connect

    Polak, J. . Lab. de Mecanique de Lille Inst. of Physical Metallurgy, Brno . Academy of Sciences); Degallaix, S. . Lab. de Mecanique de Lille); Kruml, T. . Academy of Sciences)

    1993-12-15

    Cyclic plastic straining of crystalline materials results in the formation of specific dislocation structures. Considerable progress in mapping and understanding internal dislocation structures has been achieved by studying single crystal behavior: however, most structural materials have a polycrystalline structure and investigations of polycrystals in comparison to single crystal behavior of simple metals prove to be very useful in understanding more complex materials. There are some classes of materials, however, with complicated structure which do not have a direct equivalent in single crystalline form. Moreover, the specific dimensions and shapes of individual crystallites play an important role both in the cyclic stress-strain response of these materials and in the formation of their interior structure in cyclic straining. Austenitic-ferritic duplex stainless steel, which is a kind of a natural composite, is a material of this type. The widespread interest in the application of duplex steels is caused by approximately doubled mechanical properties and equal corrosion properties, when compared with classical austenitic stainless steels. Fatigue resistance of these steels as well as the surface damage evolution in cyclic straining have been studied; however, much less is known about the internal substructure development in cyclic straining. In this study the dislocation arrangement in ferritic and austenitic grains of the austenitic-ferritic duplex steel alloyed with nitrogen and cyclically strained with two strain amplitudes, is reported and compared to the dislocation arrangement found in single and polycrystals of austenitic and ferritic materials of a similar composition and with the surface relief produced in cyclic plastic straining.

  15. Tailoring noncollinear magnetism by misfit dislocation lines

    NASA Astrophysics Data System (ADS)

    Finco, Aurore; Hsu, Pin-Jui; Kubetzka, André; von Bergmann, Kirsten; Wiesendanger, Roland

    2016-12-01

    The large epitaxial stress induced by the misfit between a triple atomic layer Fe film and an Ir(111) substrate is relieved by the formation of a dense dislocation line network. Spin-polarized scanning tunneling microscopy investigations show that the strain is locally varying within the Fe film and that this variation affects the magnetic state of the system. Two types of dislocation line regions can be distinguished and both exhibit spin spirals with strain-dependent periods (ranging from 3 to 10 nm ). Using a simple micromagnetic model, we attribute the changes of the period of the spin spirals to variations of the effective exchange coupling in the magnetic film. This assumption is supported by the observed dependence of the saturation magnetic field on the period of the zero-field spin spiral. Moreover, magnetic skyrmions appear in an external magnetic field only in one type of dislocation line area, which we impute to the different pinning properties of the dislocation lines.

  16. Left Dislocation in Near-Native French

    ERIC Educational Resources Information Center

    Donaldson, Bryan

    2011-01-01

    The present study is concerned with the upper limits of SLA--specifically, mastery of the syntax-discourse interface in successful endstate learners of second-language (L2) French (near-native speakers). Left dislocation (LD) is a syntactic means of structuring spoken French discourse by marking topic. Its use requires speakers to coordinate…

  17. Dislocations - Multiple Languages: MedlinePlus

    MedlinePlus

    ... XYZ List of All Topics All Dislocations - Multiple Languages To use the sharing features on this page, please enable JavaScript. Arabic (العربية) French (français) Russian (Русский) Somali (af Soomaali) Spanish (español) Arabic (العربية) ...

  18. An Acoustic Profile of Right-Dislocations in French.

    ERIC Educational Resources Information Center

    Ashby, William J.

    1994-01-01

    Provides an acoustic profile of the prosody of right-dislocations in French, using the CECIL computer hardware and software package to analyze 28 right-dislocations occurring in a corpus of natural French discourse. It was found that, although right-dislocations appear to fulfill various functional roles in discourse, no correlation appears…

  19. The Perceptions of Dislocated Workers under the Workforce Investment Act

    ERIC Educational Resources Information Center

    Wilson, Michael S.; Brown, James M.

    2012-01-01

    This descriptive qualitative case study investigated the perceptions of dislocated workers offered program services through the Workforce Investment Act's (WIA) Dislocated Worker program in Minnesota. This research focused on recently dislocated workers who lost their jobs through no fault of their own and hence were eligible for unemployment…

  20. Enhanced annealing of the dislocation network under irradiation

    SciTech Connect

    Mordehai, Dan; Martin, Georges

    2011-07-01

    In crystalline metals, the dislocation network is the main source of internal strain, while irradiation steadily injects new sources of internal strain (point defects, defect clusters). As a consequence, the evolution of the dislocation network is driven by irradiation. While the atomistic mechanisms by which the forcing proceeds have long been suggested, namely the partitioning of defect elimination between dislocations and other defect sinks, both in stationary or transient regimes, some of the macroscopic consequences, such as irradiation enhanced dislocation annealing and irradiation driven recrystallization, are left unexplained. In this work we show that dislocation sink strengths for point defects are altered in the presence of neighboring dislocations and their climb motion is coordinated with the dislocation microstructure. A climb model, which takes into account the dislocation network, provides the mechanism for coordinated climb, which is shown to ease dislocation annealing. In particular, we demonstrate that coordinated dislocation climb accelerates the annihilation of dislocation pairs with the opposite sign and the repulsion of dislocations of the same sign, thereby, among other things, promoting the annealing of small-angle tilt boundaries by subgrain rotation.

  1. Dislocation core fields and forces in FCC metals

    SciTech Connect

    Henager, Charles H.; Hoagland, Richard G.

    2004-04-01

    Atomistic models were used to obtain dislocation core fields for edge, screw, and mixed dislocations in Al and Cu using EAM. Core fields are analyzed using a line force dipole representation, with dilatant and dipole terms. The core field contribution to the force between dislocations is shown to be significant for interactions within 50b.

  2. Hydrogen diffusion in the elastic fields of dislocations in iron

    NASA Astrophysics Data System (ADS)

    Sivak, A. B.; Sivak, P. A.; Romanov, V. A.; Chernov, V. M.

    2016-12-01

    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 × 1014 m-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 of 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.

  3. Assessment of hardening due to dislocation loops in bcc iron: Overview and analysis of atomistic simulations for edge dislocations

    NASA Astrophysics Data System (ADS)

    Bonny, G.; Terentyev, D.; Elena, J.; Zinovev, A.; Minov, B.; Zhurkin, E. E.

    2016-05-01

    Upon irradiation, iron based steels used for nuclear applications contain dislocation loops of both < 100 > and ½ < 111 > type. Both types of loops are known to contribute to the radiation hardening and embrittlement of steels. In the literature many molecular dynamics works studying the interaction of dislocations with dislocation loops are available. Recently, based on such studies, a thermo-mechanical model to threat the dislocation - dislocation loop (DL) interaction within a discrete dislocation dynamics framework was developed for ½ < 111 > loops. In this work, we make a literature review of the dislocation - DL interaction in bcc iron. We also perform molecular dynamics simulations to derive the stress-energy function for < 100 > loops. As a result we deliver the function of the activation energy versus activation stress for < 100 > loops that can be applied in a discrete dislocation dynamics framework.

  4. 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

  5. Elbow dislocation with irreparable fracture radial head

    PubMed Central

    Tanna, Dilip

    2013-01-01

    Background: Treatment of elbow dislocation with irreparable radial head fracture needs replacement of radial head to achieve stability of elbow. An alternate method in cases of elbow dislocation with radial head fracture can be resection of radial head with repair of medial collateral ligament. We report a retrospective analysis of cases of elbow dislocation with irreparable radial head treated by excision head of radius and repair of MCL. Materials and Methods: Nine patients of elbow dislocation with associated irreparable fractures of the head of the radius were included in this analysis (6 F:3 M, Age: 35-47 years). Radial head excision was done through the lateral approach and MCL was sutured using no 3 Ethibond using medial approach. Above elbow plaster was given for 6 weeks and gradual mobilization was done thereafter. All patients were assessed at final followup using Mayo elbow performance score (MEPS). Results: Mean followup was 19.55 ± 7.12 months (range 14-36 months). There was no extension deficit when compared to opposite side with mean range of flexion of 138.8° ± 6.97° (range 130 -145°). Mean pronation was 87.7° ± 4.4° (range 80-90°) and mean supination was 87.7 ± 4.62° (range 80-90°). The mean MEPS was 98.8 ± 3.33 (range 90-100). No patient had pain, sensory complaints, subluxation or redislocation. All were able to carry out their daily activities without disability. Conclusion: Radial head excision with MCL repair is an acceptable option for treatment of patients with elbow dislocation and irreparable radial head fracture. PMID:23798760

  6. Late treatment of a dorsal transscaphoid, transtriquetral perilunate wrist dislocation with avascular changes of the lunate.

    PubMed

    Gellman, H; Schwartz, S D; Botte, M J; Feiwell, L

    1988-12-01

    The outcome of delayed treatment of an unreduced transscaphoid, transtriquetral, perilunate fracture dislocation of the carpus is unpredictable. Long-term follow-up observations in a 22-year-old man treated three months postinjury showed changes in the lunate consistent with avascular necrosis at the time of open reduction and internal fixation. Early resolution of this was evident by nine months, and complete resolution was seen at the follow-up examination (four years and two months). Despite delay in treatment, this patient had full, pain-free wrist motion. Consequently, avascular changes of the carpus following wrist dislocation do not preclude a good result. Anatomic reduction of the scaphoid, as well as the midcarpal joint, and restoration of the articular surface of the lunate, are most important in determining prognosis.

  7. Dislocation of the ulnar nerve at the elbow in an elite wrestler

    PubMed Central

    Molnar, Szabolcs Lajos; Lang, Peter; Skapinyecz, János; Shadgan, Babak

    2011-01-01

    Dislocation of the ulnar nerve is uncommon among the general population, but it has been reported more frequently in athletes who use their upper limbs to make forceful and resisted flexion of elbow joint. The authors report a unique case of ulnar nerve dislocation in an elite wrestler treated by partial epicondylectomy and subcutaneous transposition of the ulnar nerve. Following the surgery, a supervised and well-designed sport-specific rehabilitation program is a necessary requirement for a rapid return to sport. Such a program requires a bilateral consultation and collaboration between treating physician and trainer of the wrestler. The athlete regained his full function and returned to wrestling after a 3-month sport-specific functional rehabilitation program. PMID:22693274

  8. Re-dislocation after corrective osteotomy for chronic dislocation of the radial head in children.

    PubMed

    Suzuki, T; Seki, A; Nakamura, T; Ikegami, H; Takayama, S; Nakamura, M; Matsumoto, M; Sato, K

    2015-11-01

    This retrospective study was designed to evaluate the outcomes of re-dislocation of the radial head after corrective osteotomy for chronic dislocation. A total of 12 children with a mean age of 11 years (5 to 16), with further dislocation of the radial head after corrective osteotomy of the forearm, were followed for a mean of five years (2 to 10). Re-operations were performed for radial head re-dislocation in six children, while the other six did not undergo re-operation ('non-re-operation group'). The active range of movement (ROM) of their elbows was evaluated before and after the first operation, and at the most recent follow-up. In the re-operation group, there were significant decreases in extension, pronation, and supination when comparing the ROM following the corrective osteotomy and following re-operation (p < 0.05). The children who had not undergone re-operation achieved a better ROM than those who had undergone re-operation. There was a significant difference in mean pronation (76° vs 0°) between the non- re-operation and the re-operation group (p = 0.002), and a trend towards increases in mean flexion (133° vs 111°), extension (0° vs 23°), and supination (62° vs 29°). We did not find a clear benefit for re-operation in children with a re-dislocation following corrective osteotomy for chronic dislocation of the radial head.

  9. [Syringomyelia and associated bone and joint diseases].

    PubMed

    Alnot, J-Y; Rossarie, R; Welby, F

    2007-05-01

    Syringomyelia can occur in patients presenting bone and joint diseases of various origins. When joint destruction of the shoulder or elbow produces little pain, a neurological cause might be involved. In this case, the disease history can be of utmost importance because an initial diagnosis of rheumatoid polyarthritis, polyosteoarthritis, or destructive joint disease can be misleading before the syringomyelic origin of the bone and joint disease becomes patent. We report two cases illustrating this association and the diagnostic pitfalls which can delay recognition of the syringomyelia. Better awareness of the prevalence of this condition should be helpful in establishing the diagnosis and in selecting patients who can benefit from neurosurgical treatment. The two cases presented here suggest that syringomyelia could be underdiagnosed in certain patients with an initially atypical presentation. A review of the current knowledge of syringomyelia suggests that arthroplasty is generally not advisable for destroyed dislocated syringomyelic joints.

  10. The dynamics of an edge dislocation in a ferromagnetic crystals

    NASA Astrophysics Data System (ADS)

    Dezhin, V. V.; Nechaev, V. N.

    2016-08-01

    The system of equations describing the bending vibrations of the dislocation in the ferromagnetic crystal is written. Elastic and magnetostrictive properties of the ferromagnetic crystals are considered isotropic. The linearization of the resulting system produced a relatively small contribution to the magnetization from the influence of dislocation. In the linear approximation of the dislocation displacement system of equation describing vibrations of a ferromagnetic crystal with an edge dislocation is obtained. The equation of motion of an edge dislocation in a ferromagnetic crystal is found.

  11. Radiation enhanced basal plane dislocation glide in GaN

    NASA Astrophysics Data System (ADS)

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

    2016-05-01

    A movement of basal plane segments of dislocations in GaN films grown by epitaxial lateral overgrowth under low energy electron beam irradiation (LEEBI) was studied by the electron beam induced current (EBIC) method. Only a small fraction of the basal plane dislocation segments were susceptible to irradiation and the movement was limited to relatively short distances. The effect is explained by the radiation enhanced dislocation glide (REDG) in the structure with strong pinning. A dislocation velocity under LEEBI with a beam current lower than 1 nA was estimated as about 10 nm/s. The results assuming the REDG for prismatic plane dislocations were presented.

  12. Dislocation kinematics: a molecular dynamics study in Cu

    NASA Astrophysics Data System (ADS)

    Oren, E.; Yahel, E.; Makov, G.

    2017-02-01

    The kinematics and kinetics of edge and screw dislocations in FCC materials were studied by molecular dynamics, with Cu as a case study. It was found that with increasing stress screw dislocations enter into the transonic regime continuously and that they remain stable up to a velocity of about 2.2 km s-1. Edge dislocations are limited by the transverse sound velocity at low stresses and discontinuously cross into the transonic regime at higher stresses. For sufficiently long edge dislocations, the subsonic-transonic transition is initiated by an athermal nucleation process. Finally, an expression for the velocity dependence of the dislocation mobility was derived.

  13. Empirical potential simulations of interstitial dislocation loops in uranium dioxide

    NASA Astrophysics Data System (ADS)

    Le Prioux, Arno; Fossati, Paul; Maillard, Serge; Jourdan, Thomas; Maugis, Philippe

    2016-10-01

    Stoichiometric circular shaped interstitial dislocation loop energies are calculated in stoichiometric UO2 by empirical potential simulation. The Burgers vector directions studied are <110> and <111>. The main structural properties of each type of interstitial dislocation loop are determined, including stacking fault energy. Defect energies are compared and a maximum size for stable <111> dislocation loops before transition to <110> dislocation loops is given. A model of dislocation loop energy based on elasticity theory is then fitted on the basis of these simulation results.

  14. Case report: congenital dislocation of the radial head –a two-in-one approach

    PubMed Central

    Karuppal, Raju; Marthya, Anwar; Raman, Rajendran V; Somasundaran, Sandhya

    2014-01-01

    Background: Congenital dislocation of the radial head of the elbow is rare. It is genetically transmitted in some cases and is often associated with syndromes, such as Nail-Patella syndrome, antecubital pterygium and ulnar dysplasia. About two thirds are posterior, with the remainder being either anterior (15%) or lateral (15%). The natural history of the condition is that symptoms are relatively benign, with only some limitation of motion and deformity. Treatment either involves early attempts at reconstruction or delayed intervention at skeletal maturity with radial head excision. We evaluated the radiographic and functional results of a two-in-one procedure (radial shortening and open reduction) in the treatment of congenital dislocation of the radial head of an eight year old girl. Objective: To describe a technique for easy reduction and maintenance of normal radiocapitellar joint anatomy in cases of congenital dislocation of the radial head. Method: We have introduced one modification to the Sachar’s method of open reduction by adding radial shortening. This can be described as a ‘two incision approach’ with the first incision for the radial shortening and the second for the open reduction of the radiocapitellar joint. The radial shaft was osteotomised first before we performed the radial head relocation. Then the overlapping part of radial shaft was trimmed. It was stabilized with a transarticular K wire fixation. Results: At one year follow up, the elbow is stable with no valgus or fixed flexion deformity. Supination has increased to 40 degrees from zero degrees. An X-ray showed reformation of the radial head with good congruity of the radiocapitellar joint and correction of the radial bow. Conclusion: As far as the authors are aware, this is the first report of congenital dislocation of the radial head being treated by radial shortening and open reduction of radiocapitellar joint through a two incision approach (two-in-one approach). This paper

  15. 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.

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

    PubMed Central

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

    2014-01-01

    Background: 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. Materials and Methods: 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. Results: 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. Conclusion: 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. PMID:25364364

  17. Electron energy can oscillate near a crystal dislocation

    NASA Astrophysics Data System (ADS)

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

    2017-01-01

    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 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 an 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.

  18. 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

  19. Elastic Stiffness of Grain Boundary Scars and Dislocation Dynamics

    NASA Astrophysics Data System (ADS)

    Shin, Homin; Bowick, Mark

    2006-03-01

    We analytically calculate the stiffness of finite-length grain boundaries (scars) on a spherical crystal within the continuum elasticity theory. The scar is composed of an isolated disclination with +1 topological charge together with a finite number of dislocations. We determine the elastic free energy of a single finite-grain boundary scar by considering interacting defects, such as Disclination-Disclination (D-D), Disclination-dislocation (D-d), and dislocation-dislocation (d-d). The harmonic potential binding dislocations to the scar is obtained by determining the free energy of a single dislocation perturbed away from its equilibrium position. The elastic spring constants so obtained are compared to experimental data on dislocation dynamics [1]. We conclude with some comments on interstitial dynamics. [1] Lipowsky, P., Bowick, M. J., Meinke, J. H., Nelson, D. R. and Bausch, A. R. Nature Mater. 4, 407-411 (2005).

  20. Dislocation dynamics in hexagonal close-packed crystals

    SciTech Connect

    Aubry, S.; Rhee, M.; Hommes, G.; Bulatov, V. V.; Arsenlis, A.

    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 bulk 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.

  1. Microfabricated AC impedance sensor

    DOEpatents

    Krulevitch, Peter; Ackler, Harold D.; Becker, Frederick; Boser, Bernhard E.; Eldredge, Adam B.; Fuller, Christopher K.; Gascoyne, Peter R. C.; Hamilton, Julie K.; Swierkowski, Stefan P.; Wang, Xiao-Bo

    2002-01-01

    A microfabricated instrument for detecting and identifying cells and other particles based on alternating current (AC) impedance measurements. The microfabricated AC impedance sensor includes two critical elements: 1) a microfluidic chip, preferably of glass substrates, having at least one microchannel therein and with electrodes patterned on both substrates, and 2) electrical circuits that connect to the electrodes on the microfluidic chip and detect signals associated with particles traveling down the microchannels. These circuits enable multiple AC impedance measurements of individual particles at high throughput rates with sufficient resolution to identify different particle and cell types as appropriate for environmental detection and clinical diagnostic applications.

  2. Joint pain

    MedlinePlus

    ... that may be done include: CBC or blood differential C-reactive protein Joint x-ray Sedimentation rate ... chap 256. Schaible H-G. Joint pain: basic mechanisms. In: McMahon SB, Koltzenburg M, Tracey I, Turk ...

  3. Joint Interdiction

    DTIC Science & Technology

    2016-09-09

    Purpose This publication has been prepared under the direction of the Chairman of the Joint Chiefs of Staff. It sets forth joint doctrine to govern the...governmental and nongovernmental organizations, multinational forces, and other interorganizational partners. It provides military guidance for the...exercise of authority by combatant commanders and other joint force commanders (JFCs), and prescribes joint doctrine for operations and training. It

  4. Magnetic resonance imaging of hip joint cartilage and labrum

    PubMed Central

    Zilkens, Christoph; Miese, Falk; Jäger, Marcus; Bittersohl, Bernd; Krauspe, Rüdiger

    2011-01-01

    Hip joint instability and impingement are the most common biomechanical risk factors that put the hip joint at risk to develop premature osteoarthritis. Several surgical procedures like periacetabular osteotomy for hip dysplasia or hip arthroscopy or safe surgical hip dislocation for femoroacetabular impingement aim at restoring the hip anatomy. However, the success of joint preserving surgical procedures is limited by the amount of pre-existing cartilage damage. Biochemically sensitive MRI techniques like delayed Gadolinium Enhanced MRI of Cartilage (dGEMRIC) might help to monitor the effect of surgical or non-surgical procedures in the effort to halt or even reverse joint damage. PMID:22053256

  5. Joint Disorders

    MedlinePlus

    A joint is where two or more bones come together, like the knee, hip, elbow, or shoulder. Joints can be damaged by many types of injuries or diseases, including Arthritis - inflammation of a joint. It causes pain, stiffness, and swelling. Over time, ...

  6. Low energy dislocation structures in epitaxy

    NASA Technical Reports Server (NTRS)

    Van Der Merwe, Jan H.; Woltersdorf, J.; Jesser, W. A.

    1986-01-01

    The principle of minimum energy was applied to epitaxial interfaces to show the interrelationship beteen misfit, overgrowth thickness and misfit dislocation spacing. The low energy dislocation configurations were presented for selected interfacial geometries. A review of the interfacial energy calculations was made and a critical assessment of the agreement between theory and experiment was presented. Modes of misfit accommodation were presented with emphasis on the distinction between kinetic effects and equilibrium conditions. Two-dimensional and three-dimensional overgrowths were treated together with interdiffusion-modified interfaces, and several models of interfacial structure were treated including the classical and the current models. The paper is concluded by indicating areas of needed investigation into interfacial structure.

  7. Transtriquetral perihamate fracture-dislocation: case report.

    PubMed

    Moraes, Frederico Barra de; Ferreira, Rodrigo Cunha; Geraldino, Stéphanie Zago; Farias, Renato Silva; Silva, Ricardo Pereira da; Kuwae, Mário Yoshihide

    2016-01-01

    The wrist is a region that is very vulnerable to injuries of the extremities. Among these injuries, fractures of the pyramidal bone (or triquetrum) in association with dislocation of the hamate and carpal instability are uncommon. They are generally correlated with high-energy trauma and may be associated with neurovascular deficits, muscle-tendon disorders, skin lesions or injuries to other carpal bones. Thus, in this report, one of these rare cases of transtriquetral perihamate fracture-dislocation with carpal instability is presented, diagnosed by means of radiography on the right wrist of the patient who presented pain, edema and limitation of flexion-extension of the carpus after trauma to the region. The stages of attending to the case are described, from the initial consultation to the surgical treatment and physiotherapy, which culminated in restoration of the strength and range of motion of the wrist.

  8. AC magnetohydrodynamic microfluidic switch

    SciTech Connect

    Lemoff, A V; Lee, A P

    2000-03-02

    A microfluidic switch has been demonstrated using an AC Magnetohydrodynamic (MHD) pumping mechanism in which the Lorentz force is used to pump an electrolytic solution. By integrating two AC MHD pumps into different arms of a Y-shaped fluidic circuit, flow can be switched between the two arms. This type of switch can be used to produce complex fluidic routing, which may have multiple applications in {micro}TAS.

  9. Dislocations: 75 years of Deformation Mechanisms

    NASA Technical Reports Server (NTRS)

    Schneider, Judy

    2009-01-01

    The selection of papers presented in this section reflect on themes to be explored at the "Dislocations: 75 years of Deformation Mechanisms" Symposium to be held at the Annual 2009 TMS meeting. The symposium was sponsored by the Mechanical Behavior of Materials Committee to give tribute to the evolution of a concept that has formed the basis of our mechanistic understanding of how crystalline solids plastically deform and how they fail.

  10. Dislocation Etching Solutions for Mercury Cadmium Selenide

    DTIC Science & Technology

    2014-09-01

    Dislocation Etching Solutions for Mercury Cadmium Selenide by Kevin Doyle and Sudhir Trivedi ARL-CR-0744 September 2014...Etching Solutions for Mercury Cadmium Selenide Kevin Doyle and Sudhir Trivedi Sensors and Electron Devices Directorate, ARL prepared by...Solutions for Mercury Cadmium Selenide 5a. CONTRACT NUMBER W811NF-12-2-0019 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) Kevin Doyle and

  11. Is conservative treatment still defensible in grade III acromioclavicular dislocation? Are there predictive factors of poor outcome?

    PubMed

    Rasmont, Quentin; Delloye, Christian; Bigare, Elisa; Van Isacker, Tom

    2015-03-01

    The optimal treatment of grade III acromioclavicular (AC) dislocation is still controversial. Recent studies recommend surgery at that stage whereas meta-analysis favours conservative management. The objective of the present investigation was to analyse a clinical series of non-operated grade III AC dislocations and to determine their functional status. Thirty-five patients treated conservatively with a grade III acromioclavicular dislocation were retrospectively reviewed. Simple shoulder test, Oxford shoulder and bilateral Constant shoulder score were used for assessment. Various predictive criteria of poor outcome, particularly scapular dyskinesis were taken into account for analysis. Overall mean and median Constant Score of the injured side were 92.9 and 94, whilst the contralateral shoulder values were respectively 94.9 and 95 (mean and median scores). Ten patients had scapular dyskinesis. Laterality, shoulder activity and scapular dyskinesis were not statistically related to worse outcome. Twenty-eight (80%) patients resumed normal activity within six months. All but two patients were subjectively very satisfied or satisfied. Conservative treatment provided satisfactory results whatever the shoulder activity. No risk factors were predictive of a poorer outcome. Conservative management should remain the first option to manage these injuries.

  12. Dislocation movement and hysteresis in Maraging blades

    NASA Astrophysics Data System (ADS)

    Di Cintio, Arianna; Marchesoni, Fabio; Ascione, Maria; Bhawal, Abhik; De Salvo, Riccardo

    2009-10-01

    All seismic isolation systems developed for gravitational-wave interferometric detectors, such as LIGO, Virgo and TAMA, make use of Maraging steel blades. The dissipation properties of these blades have been studied at low frequencies, by using a geometric anti-spring (GAS) filter, which allowed the exploration of resonant frequencies below 100 mHz. At this frequency an anomalous transfer function was observed in the GAS filter: this is one of several motivations for this work. The many unexpected effects observed and measured are explainable by the collective movement of dislocations inside the material described with the statistic of self-organised criticality. At low frequencies, below 200 mHz, the dissipation mechanism can subtract elasticity from the system even leading to sudden collapse. While Young's modulus is weaker, excess dissipation is observed. At higher frequencies the applied stress is probably too fast to allow the full growth of dislocation avalanches, and less losses are observed, thus explaining the higher Q-factor in this frequency range. The domino effect that leads to the release of entangled dislocations allows the understanding of the random walk of the Virgo and TAMA inverted pendula, the anomalous GAS filter transfer function as well as the loss of predictability of the ring-down decay in the LIGO seismic attenuation system inverted pendula.

  13. Dislocation Theory of the Fatigue of Metals

    NASA Technical Reports Server (NTRS)

    Machlin, E S

    1949-01-01

    A dislocation theory of fatigue failure for annealed solid solutions is presented. On the basis of this theory, an equation giving the dependence of the number of cycles for failure on the stress, the temperature, the material parameters, and the frequency is derived for uniformly stressed specimens. The equation is in quantitative agreement with the data. Inasmuch as one material parameter is indicated to be temperature-dependent and its temperature dependence is unknown, it is impossible to predict the temperature dependence of the number of cycles for failure. A predicted quantitative correlation between fatigue and creep was found to exist, which suggests the practical possibility of obtaining fatigue data for annealed solid solutions and elements from steady-state creep-rate data for these materials. As a result of this investigation, a modification of the equation for the steady-state creep rate previously developed on the basis of the dislocation theory is suggested. Additional data are required to verify completely the dislocation theory of fatigue.

  14. Management of an Uncomplicated Posterior Elbow Dislocation

    PubMed Central

    Blackard, Douglas; Sampson, Jo-Ann

    1997-01-01

    Objective: To present a case of an uncomplicated posterior elbow dislocation in a US World Cup athlete and discuss her rehabilitation. Background: Traditional protocol for management of this injury has been splint immobilization for several weeks, but research suggests a shortened duration of immobilization and early active motion. Differential Diagnosis: Elbow dislocation with possible fracture. Treatment: The dislocation was reduced and a compression bandage and sling were applied. The sports medicine staff and athlete determined that rehabilitation would involve limited immobilization with a posterior splint. Also, active range-of- motion exercises were to be incorporated early in the range-of- motion program to decrease pain at the articulation. Uniqueness: The athlete was not immobilized and her aggressive five-phase rehabilitation program progressed according to decrease in inflammation and increase in range of motion and strength. Conclusions: Shortened immobilization and return to World Championship competition 6 weeks postinjury had no longterm adverse effects on the athlete. ImagesFig 1.Fig 2.Fig 3.Fig 4.Fig. 5. PMID:16558436

  15. Normal and abnormal temporomandibular joints as demonstrated by magnetic resonance imaging.

    PubMed

    Kreipke, D L; Conces, D J; Sondhi, A; Lappas, J C; Augustyn, G T

    1986-01-01

    Magnetic resonance imaging of the temporomandibular joint (TMJ) was performed on two normal volunteer subjects and two symptomatic subjects using a 0.15 T resistive magnet. A spin echo pulse sequence with a TE of 38 ms and a TR of 500 ms was employed. The TMJ meniscus is a low signal structure, and the bilaminar zone behind it is a relatively high signal structure. In normal closed mouths, the demarcation between meniscus and bilaminar zone is located at the vertex position above the mandibular condyle. When the condyle translates, the posterior portion of the meniscus bulges into the joint space. Dislocated meniscus can be identified by a gray mass anterior to the condylar head. The joint space is filled with the higher signal of the bilaminar zone. In non-reducible dislocations, the meniscus remains anterior to the condylar head with opening of the mouth. Reduced dislocations appear similar to normal joints in the open mouth.

  16. Probing the character of ultra-fast dislocations

    SciTech Connect

    Rudd, R. E.; Ruestes, C. J.; Bringa, E. M.; Remington, B. A.; Remington, T. P.; Meyers, M. A.

    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 to 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.

  17. 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

  18. 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

  19. Probing the character of ultra-fast dislocations

    PubMed Central

    Ruestes, C. J.; Bringa, E. M.; Rudd, R. E.; Remington, B. A.; Remington, T. P.; Meyers, M. A.

    2015-01-01

    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 to 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. The simulated configuration enables a new class of experiments to probe average dislocation velocity at very high applied shear stress. PMID:26592764

  20. 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

  1. Atomistic calculations of dislocation core energy in aluminium

    NASA Astrophysics Data System (ADS)

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

    2017-02-01

    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 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 the Burgers vector. These calculations show that, for the face-centered-cubic aluminium explored, the dislocation core energy follows the same functional dependence on β as the dislocation elastic energy: Ec=A sin2β +B cos2β , and this dependence is independent of temperature between 100 and 300 K. By further analyzing the energetics of an extended dislocation core, we elucidate the relationship between the core energy and the core radius of a perfect versus an extended dislocation. With our methodology, the dislocation core energy can accurately be accounted for in models of dislocation-mediated plasticity.

  2. Analogies between continuum dislocation theory, continuum mechanics and fluid mechanics

    NASA Astrophysics Data System (ADS)

    Silbermann, C. B.; Ihlemann, J.

    2017-03-01

    Continuum Dislocation Theory (CDT) relates gradients of plastic deformation in crystals with the presence of geometrically necessary dislocations. Interestingly, CDT shows striking analogies to other branches of continuum mechanics. The present contribution demonstrates this on two essential kinematical quantities which reflect tensorial dislocation properties: the (resultant) Burgers vector and the dislocation density tensor. First, the limiting process for the (resultant) Burgers vector from an integral to a local quantity is performed analogously to the limiting process from the force vector to the traction vector. By evaluating the balance of forces on a tetrahedral volume element, Cauchy found his famous formula relating traction vector and stress tensor. It is shown how this procedure may be adopted to a continuously dislocated tetrahedron. Here, the conservation of Burger’s vector implicates the introduction of the dislocation density tensor. Second, analogies between the plastic flow of a continuously dislocated solid and the liquid flow of a fluid are highlighted: the resultant Burgers vector of a dislocation ensemble plays a similar role as the (resultant) circulation of a vortex tube. Moreover, both vortices within flowing fluids and dislocations within deforming solids induce discontinuities in the velocity field and the plastic distortion field, respectively. Beyond the analogies, some peculiar properties of the dislocation density tensor are presented as well.

  3. Brachial artery injury due to closed posterior elbow dislocation: case report☆

    PubMed Central

    Miyazaki, Alberto Naoki; Fregoneze, Marcelo; Santos, Pedro Doneux; do Val Sella, Guilherme; Checchia, Caio Santos; Checchia, Sergio Luiz

    2016-01-01

    An association between closed posterior elbow dislocation and traumatic brachial artery injury is rare. Absence of radial pulse on palpation is an important warning sign and arteriography is the gold-standard diagnostic test. Early diagnosis is essential for appropriate treatment to be provided. This consists of joint reduction and immobilization, along with urgent surgical restoration of arterial flow. Here, a case (novel to the Brazilian literature) of an association between these injuries (and the treatment implemented) in a 27-year-old male patient is reported. These injuries were sustained through physical assault. PMID:27069896

  4. Treatment of acute and chronic elbow instability with a hinged external fixator after fracture dislocation.

    PubMed

    Zilkens, Christoph; Graf, Markus; Anastasiadis, Alexandros; Smajic, Samir; Muhr, Gert; Kälicke, Thomas

    2009-04-01

    This is a retrospective analysis of the clinical and radiological outcome in 24 patients with acute or chronic posttraumatic elbow instability, who were treated with open reduction, internal fixation and a hinged external fixator. The instability was acute after elbow fracture dislocation in 11 cases; the other 13 had chronic posttraumatic instability of the elbow. Concentric stability and a sufficient range of motion of the elbow joint were achieved in all cases. The addition of a hinged external fixator in noncompliant patients, who underwent open reduction and internal fixation of an acute or chronic posttraumatic unstable elbow, allows early intensive mobilisation and can improve the clinical outcome after these complex elbow injuries.

  5. Brachial artery injury due to closed posterior elbow dislocation: case report.

    PubMed

    Miyazaki, Alberto Naoki; Fregoneze, Marcelo; Santos, Pedro Doneux; do Val Sella, Guilherme; Checchia, Caio Santos; Checchia, Sergio Luiz

    2016-01-01

    An association between closed posterior elbow dislocation and traumatic brachial artery injury is rare. Absence of radial pulse on palpation is an important warning sign and arteriography is the gold-standard diagnostic test. Early diagnosis is essential for appropriate treatment to be provided. This consists of joint reduction and immobilization, along with urgent surgical restoration of arterial flow. Here, a case (novel to the Brazilian literature) of an association between these injuries (and the treatment implemented) in a 27-year-old male patient is reported. These injuries were sustained through physical assault.

  6. Acute patellar dislocation with multiple ligament injuries after knee dislocation and single session reconstruction.

    PubMed

    Gormeli, Gokay; Gormeli, Cemile Ayse; Karakaplan, Mustafa; Gurbuz, Sukru; Ozdemir, Zeynep; Ozer, Mustafa

    2016-06-01

    Knee dislocation is a relatively rare condition of all orthopaedic injuries. Accompanying multiple ligament injuries are common after knee dislocations. A 41-year-old male presented to the emergency department suffering from right knee dislocation in June 2013. The patient had anterior cruciate ligament, medial collateral ligament (MCL), medial patellofemoral ligament (MPFL) rupture, and lateral meniscal tear. A single-bundle anatomic reconstruction, medial collateral ligament reconstruction, medial patellofemoral ligament reconstruction and meniscus repair were performed in single session. At twelve months follow-up; there was 160º flexion and 10° extension knee range of motion. Lysholm knee score was 90. Extensive forces can cause both MCL and MPFL injury due to overload and the anatomical relationship between these two structures. Therefore, patients with valgus instability should be evaluated for both MPFL and MCL tears to facilitate successful treatment.

  7. AC Losses of Prototype HTS Transmission Cables

    SciTech Connect

    Demko, J.A.; Dresner, L.; Hughey, R.L.; Lue, J.W.; Olsen, S.K.; Sinha, U.; Tolbert, J.C.

    1998-09-13

    Since 1995 Southwire Company and Oak Ridge National Laboratory (ORNL) have jointly designed, built, and tested nine, l-m long, high temperature superconducting (HTS) transmission cable prototypes. This paper summarizes the AC loss measurements of five of the cables not reported elsewhere, and compares the losses with each other and with theory developed by Dresner. Losses were measured with both a calorimetric and an electrical technique. Because of the broad resistive transition of the HTS tapes, the cables can be operated stably beyond their critical currents. The AC losses were measured in this region as well as below critical currents. Dresner's theory takes into account the broad resistive transition of the HTS tapes and calculates the AC losses both below and above the critical current. The two sets of AC 10SS data agree with each other and with the theory quite welL In particular, at low currents of incomplete penetration, the loss data agree with the theoretical prediction of hysteresis loss based on only the outer two Iayers carrying the total current.

  8. "Dislocation", shelter, and crisis: Afghanistan's refugees and notions of home.

    PubMed

    Emmott, S

    1996-02-01

    Millions of people have become refugees or been displaced within Afghanistan during 17 years of war within the country. Conversations with women in a camp for the displaced reveal what it means for women to lose their homes, especially in the context of ongoing instability and conflict. Sections discuss homelessness in Kabul, linking psycho-social and practical needs, coping with dislocation, stability and land ownership, mobility and security, family breakdown, temporary and permanent settlements, and meeting needs versus creating dependency. The author concludes that among people displaced from their homes for so many years, their physical and spiritual homes nonetheless remain inseparable from their lives. It is important to maintain the individual notion of home if life is to be worth living and hope retained. Relief agencies must help in an appropriate manner and to an appropriate extent. Oxfam has been working beyond the refugee camps, in a return to the city of Kabul, since July 1995. When this article was written, the NGO was involved in a joint venture to restore the piped water supply which, like the electricity supply, was looted and damaged. It also plans to distribute plastic sheeting for use as roofs and floor covering during the winter. Oxfam currently plans discreet activities rather than an integrated approach.

  9. Hinged external fixation for Regan-Morrey type I and II fractures and fracture-dislocations.

    PubMed

    Castelli, Alberto; D'amico, Salvatore; Combi, Alberto; Benazzo, Francesco

    2016-06-01

    Elbow fracture-dislocation is always demanding to manage due to the considerable soft-tissue swelling or damage involved, which can make an early open approach and ligamentous reconstruction impossible. The purpose of this study was to evaluate the role of elbow hinged external fixation (HEF) as a definitive treatment in patients with elbow dislocations associated with Regan-Morrey (R-M) type I and II coronoid fractures and soft-tissue damage. We treated 11 patients between 2010 and 2012 with HEF. Instability tests and standard X-ray examinations were performed before surgery and 1-3 to 3-6 months after surgery, respectively. All patients underwent a preoperative CT scan. Outcomes were assessed with a functional assessment scale (Mayo Elbow Performance Score, MEPS) that included 4 parameters: pain, ROM, stability, and function. The results were good or excellent in all 11 patients, and no patient complained of residual instability. Radiographic examination showed bone metaplasia involving the anterior and medial sides of the joint in 5 patients. HEF presented several advantages: it improves elbow stability and it avoids long and demanding surgery in particular in cases with large soft tissue damage. We therefore consider elbow HEF to be a viable option for treating R-M type I and II fracture-dislocations.

  10. Zygomatic arch-atlas wing stabilization in 5 dogs with atlanto-occipital dislocation

    PubMed Central

    DOLERA, Mario; MALFASSI, Luca; BIANCHI, Cristina; CARRARA, Nancy; CORBETTA, Laura; FINESSO, Sara; MARCARINI, Silvia; MAZZA, Giovanni; PAVESI, Simone; SALA, Massimo

    2016-01-01

    The aim of this work was to present a novel minimally invasive surgical stabilization technique for canine atlanto-occipital dislocation and to report the associated magnetic resonance imaging (MRI) findings. All 5 dogs in this case series underwent 1.5 T MRI of the head and neck and 3 underwent both MRI and computed tomography (CT). Atlanto-occipital dislocations were diagnosed based on the increased joint space between the occipital condyles and the atlas on MRI. Surgery was performed immediately with a never previously described fixation technique based on an external ligature. The stabilization was performed via 4 holes drilled in the zygomatic processes and in the atlas wings on each side. A nylon monofilament of 1 mm diameter was inserted in the 4 holes, and an O-shaped ligature was carried out externally to the skin through the ipsilateral zygomatic arch. Ligatures were removed within 2 months. At the postsurgical follow-up examination, 14 days after surgery, all dogs were found to be ambulatory. Atlanto-occipital stability was assessed by clinical examination with an average of 24 months of follow-up. The positive outcomes in this case series suggest that atlanto-occipital dislocation may be surgically treated with this novel technique, irrespective of the severity of the clinical presentation and associated lesions observed on MRI. PMID:26923031

  11. Numerical simulation on slabs dislocation of Zipingpu concrete faced rockfill dam during the Wenchuan earthquake based on a generalized plasticity model.

    PubMed

    Xu, Bin; Zhou, Yang; Zou, Degao

    2014-01-01

    After the Wenchuan earthquake in 2008, the Zipingpu concrete faced rockfill dam (CFRD) was found slabs dislocation between different stages slabs and the maximum value reached 17 cm. This is a new damage pattern and did not occur in previous seismic damage investigation. Slabs dislocation will affect the seepage control system of the CFRD gravely and even the safety of the dam. Therefore, investigations of the slabs dislocation's mechanism and development might be meaningful to the engineering design of the CFRD. In this study, based on the previous studies by the authors, the slabs dislocation phenomenon of the Zipingpu CFRD was investigated. The procedure and constitutive model of materials used for finite element analysis are consistent. The water elevation, the angel, and the strength of the construction joints were among major variables of investigation. The results indicated that the finite element procedure based on a modified generalized plasticity model and a perfect elastoplastic interface model can be used to evaluate the dislocation damage of face slabs of concrete faced rockfill dam during earthquake. The effects of the water elevation, the angel, and the strength of the construction joints are issues of major design concern under seismic loading.

  12. Numerical Simulation on Slabs Dislocation of Zipingpu Concrete Faced Rockfill Dam during the Wenchuan Earthquake Based on a Generalized Plasticity Model

    PubMed Central

    Xu, Bin; Zou, Degao

    2014-01-01

    After the Wenchuan earthquake in 2008, the Zipingpu concrete faced rockfill dam (CFRD) was found slabs dislocation between different stages slabs and the maximum value reached 17 cm. This is a new damage pattern and did not occur in previous seismic damage investigation. Slabs dislocation will affect the seepage control system of the CFRD gravely and even the safety of the dam. Therefore, investigations of the slabs dislocation's mechanism and development might be meaningful to the engineering design of the CFRD. In this study, based on the previous studies by the authors, the slabs dislocation phenomenon of the Zipingpu CFRD was investigated. The procedure and constitutive model of materials used for finite element analysis are consistent. The water elevation, the angel, and the strength of the construction joints were among major variables of investigation. The results indicated that the finite element procedure based on a modified generalized plasticity model and a perfect elastoplastic interface model can be used to evaluate the dislocation damage of face slabs of concrete faced rockfill dam during earthquake. The effects of the water elevation, the angel, and the strength of the construction joints are issues of major design concern under seismic loading. PMID:25013857

  13. Dislocation-related plasticity of ceria-stabilized zirconia polycrystals

    SciTech Connect

    Zhe, X.; Hendry, A.; Wang, C.

    1996-06-01

    Much higher plastic strain of 4% in Ce-TZP ceramics was produced by a novel thermal-mechanical process below 450 C. Observation by TEM showed that there were abundant dislocation pile-ups associated with a few martensitic laths in the deformed samples. The density of dislocations increased with thermal-mechanical cycles. These suggested that dislocation multiplication was caused by the high local stress concentration in front of a martensitic lath during the thermal-mechanical deformation. The generation and movement of dislocations introduced extra plasticity beside the transformation plasticity caused by martensite. Meanwhile, movement of dislocations relaxes the interface stress at martensitic laths to prevent reverse martensitic transformation and early cracking of the specimens. The results are discussed in terms of thermal-mechanical action and dislocation multiplication.

  14. Simultaneous Bilateral Fracture Dislocation of the Talus: A Case Report

    PubMed Central

    Taraz-Jamshidi, Mohammad Hosein; Shapari, Omid; Shiravani, Reza; Moalemi, Saeed; Birjandinejad, Ali

    2013-01-01

    Introduction Fracture - dislocations of the talus are typically due to high energy injuries. Displaced fracture - dislocations of the talus have poor outcomes in general and complications are common. Although talar fracture is common and comprises the second most common tarsal fracture, bilateral fracture - dislocations of the talus are rare. Not many reports regarding the subject can be found in the literature. Case Presentation We report a patient with bilateral fracture - dislocations of the talus treated by open reduction and internal fixation. This patient was a 25 year-old man who sustained bilateral fracture - dislocation of the talus due to a motor vehicle accident. Conclusions Bilateral talar fracture - dislocation is rare. The surgical approach discussed together with the pathomechanics of this injury can yield good short term results. PMID:24350160

  15. 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

  16. Atomistic simulations of dislocation pileup: Grain boundaries interaction

    SciTech Connect

    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 of these kinetic processes with the available slip systems across the GB and atomic structures of the GB.

  17. Isolated volar carpometacarpal dislocation of the fifth digit.

    PubMed

    Lintner, S A; Rettig, A C

    1995-12-01

    McWharter first described volar carpometacarpal dislocations of the fifth digit in 1918. Since then, 14 cases have been reported in the medical literature. Berg and Murphy were first to report a case of ulnopalmar dislocation that was successfully treated with closed reduction and immobilization. Previously reported cases required internal fixation with or without open reduction. We report a fifth carpometacarpal ulnopalmar dislocation, treated with closed reduction and casting.

  18. 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.

  19. Dislocations: do you want them moving or in 3D ?

    NASA Astrophysics Data System (ADS)

    Cordier, Patrick; Boioli, Francesca; Bollinger, Caroline; Idrissi, Hosni; Mussi, Alexandre; Clitton Nzogang, Billy; Schryvers, Dominique

    2016-04-01

    Plastic deformation of minerals and rocks can be explained in most cases by the presence of crystal defects. Among those, dislocations represent the most efficient strain-producing actors of deformation. The physics of deformation by dislocations is complex since it is intrinsically multiscale. At the atomic scale, the dislocation core structure controls a fundamental property: their mobility. However, the plastic strain results from the collective behavior of dislocations which can be understood only at the mesoscopic scale. Multiscale numerical modeling has provided a lot of insights on these aspects in the recent years, also in mineral physics. These progress were calling for parallel developments in experiments and characterization. Here we present two studies on dislocations in olivine deformed under lithospheric conditions based in recent developments in transmission electron microscopy. We present plastic deformation experiments performed on olivine in situ, in the transmission electron microscope, at room temperature. The ductile behavior is made possible thanks to the very small size of the specimens (maximum dimension < 5μm) which are prepared by focused ion beam and strained in a special Micro-Electro-Mechanical-System (MEMS) device called push-to-pull (PI 95 TEM PicoIndenter from Hysitron). By performing experiments under constant load, the velocity of [001] screw dislocations has been measured as a function of stress. This mobility law has then been introduced in a Dislocation Dynamics model to determine the stress strain curves. We present also some recent developments on electron tomography of dislocations performed on olivine. The difficulty is here to keep diffraction conditions strictly constant over a wide range of tilt acquisitions. We present some examples obtained by imaging dislocations in weak-beam dark-field using precession electron diffraction. The analysis of dislocation microstructures in 3D is used to characterize dislocations glide

  20. Dislocation structure of the magnesium nanocrystal in uniaxial loading

    NASA Astrophysics Data System (ADS)

    Vlasova, A. M.; Nikonov, A. Yu.; Zhuravlev, A. K.; Kesarev, A. G.

    2016-11-01

    We report on molecular-dynamics (MD) simulations of compression loading of nanocrystalline magnesium modeled by the embedded-atom method (EAM) potential. It is shown that plastic deformation is by basal slip and (102) twinning. The formation of stable configurations of dislocation grids is observed. Some dislocation reactions are suggested to explain the occurrence of grids. The structure of the dislocation core is shown with the Burgers vector 1 /18 [0 4 ¯43 ] .

  1. Significance of Diffusion Tensor Imaging of Vastus Medialis Oblique in Recurrent Patellar Dislocation

    PubMed Central

    Liu, Li-Si; Zheng, Zhuo-Zhao; Yuan, Hui-Shu

    2017-01-01

    Background: Numerous studies have investigated the influence of osseous factors on patellofemoral joint instability, but research on the influence of dynamic muscle factors in vivo is still in the exploratory stage. This study aimed to use magnetic resonance imaging (MRI) and diffusion tensor imaging (DTI) to evaluate vastus medialis oblique (VMO) fiber bundles in patients with recurrent patellar dislocation to explore the changes in muscle morphology and function. Methods: This prospective study involved 30 patients (7 males and 23 females; average age, 21.4 ± 3.8 years) clinically diagnosed with recurrent patellar dislocation in Peking University Third Hospital and 30 healthy volunteers matched for age, sex, and body mass index in our medical school between January 2014 and October 2014. None of the patients had a recent history of traumatic patellar dislocation or transient patellar dislocation. All patients underwent conventional MRI and DTI of the knee. The cross-sectional area of the VMO on MRI and the fractional anisotropy (FA), apparent diffusion coefficient (ADC), and primary (λ1), secondary (λ2), and three-level characteristic (λ3) values on DTI were measured. The independent-samples t-test was used to compare these parameters between the two groups. Results: Compared with the control group, the patient group showed significantly higher FA values (0.39 ± 0.05 vs. 0.33 ± 0.03) and significantly lower ADC (1.51 ± 0.13 vs. 1.58 ± 0.07), λ2 (4.96 ± 0.13 vs. 5.04 ± 0.07), and λ3 values (4.44 ± 0.14 vs. 4.58 ± 0.07; t = 5.99, t = –2.58, t = –3.02, and t = –4.88, respectively; all P < 0.05). Cross-sectional VMO area and λ1 values did not differ between the two groups (t = –1.82 and t = 0.22, respectively; both P > 0.05). Conclusions: The functional status of the VMO is closely associated with recurrent patellar dislocation. MRI, especially DTI (FA, ADC, λ2, and λ3), can detect early changes in VMO function and might facilitate the

  2. Tevatron AC dipole system

    SciTech Connect

    Miyamoto, R.; Kopp, S.E.; Jansson, A.; Syphers, M.J.; /Fermilab

    2007-06-01

    The AC dipole is an oscillating dipole magnet which can induce large amplitude oscillations without the emittance growth and decoherence. These properties make it a good tool to measure optics of a hadron synchrotron. The vertical AC dipole for the Tevatron is powered by an inexpensive high power audio amplifier since its operating frequency is approximately 20 kHz. The magnet is incorporated into a parallel resonant system to maximize the current. The use of a vertical pinger magnet which has been installed in the Tevatron made the cost relatively inexpensive. Recently, the initial system was upgraded with a more powerful amplifier and oscillation amplitudes up to 2-3{sigma} were achieved with the 980 GeV proton beam. This paper discusses details of the Tevatron AC dipole system and also shows its test results.

  3. Interfacial dislocation motion and interactions in single-crystal superalloys

    SciTech Connect

    Liu, B.; Raabe, D.; Roters, F.; Arsenlis, A.

    2014-10-01

    The early stage of high-temperature low-stress creep in single-crystal superalloys is characterized by the rapid development of interfacial dislocation networks. Although interfacial motion and dynamic recovery of these dislocation networks have long been expected to control the subsequent creep behavior, direct observation and hence in-depth understanding of such processes has not been achieved. Incorporating recent developments of discrete dislocation dynamics models, we simulate interfacial dislocation motion in the channel structures of single-crystal superalloys, and investigate how interfacial dislocation motion and dynamic recovery are affected by interfacial dislocation interactions and lattice misfit. Different types of dislocation interactions are considered: self, collinear, coplanar, Lomer junction, glissile junction, and Hirth junction. The simulation results show that strong dynamic recovery occurs due to the short-range reactions of collinear annihilation and Lomer junction formation. The misfit stress is found to induce and accelerate dynamic recovery of interfacial dislocation networks involving self-interaction and Hirth junction formation, but slow down the steady interfacial motion of coplanar and glissile junction forming dislocation networks. The insights gained from these simulations on high-temperature low-stress creep of single-crystal superalloys are also discussed.

  4. Dislocation luminescence in GaN single crystals under nanoindentation

    PubMed Central

    2014-01-01

    This work presents an experimental study on the dislocation luminescence in GaN by nanoindentation, cathodoluminescence, and Raman. The dislocation luminescence peaking at 3.12 eV exhibits a series of special properties in the cathodoluminescence measurements, and it completely disappears after annealing at 500°C. Raman spectroscopy shows evidence for existence of vacancies in the indented region. A comprehensive investigation encompassing cathodoluminescence, Raman, and annealing experiments allow the assignment of dislocation luminescence to conduction-band-acceptor transition involving Ga vacancies. The nanoscale plasticity of GaN can be better understood by considering the dislocation luminescence mechanism. PMID:25593548

  5. Fractal analysis of deformation-induced dislocation patterns

    SciTech Connect

    Zaiser, M. ); Bay, K. . Inst. fuer Theoretische und Angewandte Physik); Haehner, P. . Joint Research Centre TU Braunschweig . Inst. fuer Metallphysik und Nukleare Festkoerperphysik)

    1999-06-22

    The paper reports extensive analyses of the fractal geometry of cellular dislocation structures observed in Cu deformed in multiple-slip orientation. Several methods presented for the determination of fractal dimensions are shown to give consistent results. Criteria are formulated which allow the distinguishing of fractal from non-fractal patterns, and implications of fractal dislocation patterning for quantitative metallography are discussed in detail. For an interpretation of the findings a theoretical model is outlined according to which dislocation cell formation is associated to a noise-induced structural transition far from equilibrium. This allows relating the observed fractal dimensions to the stochastic properties of deformation by collective dislocation glide.

  6. Surface dislocation nucleation controlled deformation of Au nanowires

    SciTech Connect

    Roos, B.; Kapelle, B.; Volkert, C. A.; Richter, G.

    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 the 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.

  7. Predicting High Temperature Dislocation Physics in HCP Crystal Structures

    SciTech Connect

    Hunter, Abigail; Carpenter, John S.; Martinez Saez, Enrique

    2016-05-09

    This report applies models and experiments to answer key questions about the way materials deform; specifics regarding phase field dislocations dynamics; as well as high temperature rolling experiments.

  8. 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·sin2β + B·cos2β, 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

  9. Mobility of edge dislocations in stressed iron crystals during irradiation

    SciTech Connect

    Korchuganov, A. V. Zolnikov, K. P.; Kryzhevich, D. S.; Chernov, V. M.; Psakhie, S. G.

    2015-10-27

    The behavior of a/2(111)(110) edge dislocations in iron in shear loading and irradiation conditions was studied by means of molecular dynamics simulation. Edge dislocations were exposed to shock waves formed by atomic displacement cascades of different energies. It was shown that starting from a certain threshold amplitude shock waves cause displacement of edge dislocations in the loaded samples. Calculations showed that the larger the shear load and the amplitude of the shock wave, the greater the displacement of dislocations in the crystallite.

  10. Dislocation conduction in Bi-Sb topological insulators

    NASA Astrophysics Data System (ADS)

    Hamasaki, Hiromu; Tokumoto, Yuki; Edagawa, Keiichi

    2017-02-01

    Previous theoretical works have predicted that when a specific condition is satisfied, dislocations in three-dimensional topological insulators form one-dimensional gapless states, which are topologically protected against disorder scattering. Here, the predicted dislocation conduction is experimentally investigated in Bi-Sb topological insulators. High-density dislocations with the Burgers vector satisfying the conductivity condition are introduced into Bi-Sb single crystals by plastic deformation. Conductivity measurements for deformed and undeformed samples and those for the deformed samples in different orientations show excess conductivity due to dislocation conduction.

  11. Spontaneous dislocation of posterior chamber intraocular lenses (PC IOLs) in patients with retinitis pigmentosa – Case series

    PubMed Central

    Masket, Samuel; Bostanci Ceran, Basak; Fram, Nicole R.

    2011-01-01

    Purpose To report the outcomes of intraocular lens (IOL) dislocation management in 6 cases with Retinitis Pigmentosa (RP). Setting Private practice, Los Angeles, USA. Design Retrospective interventional case series. Methods The medical reports of six eyes of four RP patients with capsule bag fixated posterior chamber IOL dislocation were retrospectively reviewed. Pre-operative data included demographics, systemic or ocular disorders, history of trauma, previous intraocular surgery and pre-operative visual acuity. Outcome measures included the type of surgery, surgical complications, elevation of intraocular pressure (IOP), ocular inflammation, cystoid macular edema (CME) and IOL dislocation at 3 months or greater post-operatively. Results The medical records of six eyes of four patients operated on between December 2009 and May 2011 were evaluated. In four cases, dislocated PC IOL implants were sutured to the sclera. In two eyes of one patient anterior chamber IOLs (AC IOLs) were implanted after PC IOLs were explanted. One eye developed CME during the follow-up period. Despite modest tilt in one case and modest decentration in another, stability and centration of the IOLs was excellent during the follow-up period. No eyes had intraocular inflammation requiring long term medical treatment, new onset glaucoma or retinal detachment. Mean follow-up time was 6.9 months (range 3-20). Conclusions Cataract surgeons should be aware of the increased risk for decentration and malposition of PC IOLs in patients with RP. Satisfactory results can be achieved by fixation of the PC IOL or AC IOL implantation. PMID:23960970

  12. Dislocation mediated alignment during metal nanoparticle coalescence

    SciTech Connect

    Lange, A. P.; Samanta, A.; Majidi, H.; Mahajan, S.; Ging, J.; Olson, T. Y.; van Benthem, K.; Elhadj, S.

    2016-09-13

    Dislocation mediated alignment processes during gold nanoparticle coalescence were studied at low and high temperatures using molecular dynamics simulations and transmission electron microscopy. Particles underwent rigid body rotations immediately following attachment in both low temperature (500 K) simulated coalescence events and low temperature (~315 K) transmission electron microscopy beam heating experiments. In many low temperature simulations, some degree of misorientation between particles remained after rigid body rotations, which was accommodated by grain boundary dislocation nodes. These dislocations were either sessile and remained at the interface for the duration of the simulation or dissociated and cross-slipped through the adjacent particles, leading to improved co-alignment. Minimal rigid body rotations were observed during or immediately following attachment in high temperature (1100 K) simulations, which is attributed to enhanced diffusion at the particles' interface. However, rotation was eventually induced by {111} slip on planes parallel to the neck groove. These deformation modes led to the formation of single and multi-fold twins whose structures depended on the initial orientation of the particles. The driving force for {111} slip is attributed to high surface stresses near the intersection of low energy {111} facets in the neck region. The details of this twinning process were examined in detail using simulated trajectories, and the results reveal possible mechanisms for the nucleation and propagation of Shockley partials on consecutive planes. Deformation twinning was also observed in-situ using transmission electron microscopy, which resulted in the co-alignment of a set of the particles' {111} planes across their grain boundary and an increase in their dihedral angle. As a result, this constitutes the first detailed experimental observation of deformation twinning during nanoparticle coalescence, validating simulation results

  13. Nonrigid image registration with crystal dislocation energy.

    PubMed

    Luo, Yishan; Chung, Albert C S

    2013-01-01

    The goal of nonrigid image registration is to find a suitable transformation such that the transformed moving image becomes similar to the reference image. The image registration problem can also be treated as an optimization problem, which tries to minimize an objective energy function that measures the differences between two involved images. In this paper, we consider image matching as the process of aligning object boundaries in two different images. The registration energy function can be defined based on the total energy associated with the object boundaries. The optimal transformation is obtained by finding the equilibrium state when the total energy is minimized, which indicates the object boundaries find their correspondences and stop deforming. We make an analogy between the above processes with the dislocation system in physics. The object boundaries are viewed as dislocations (line defects) in crystal. Then the well-developed dislocation energy is used to derive the energy assigned to object boundaries in images. The newly derived registration energy function takes the global gradient information of the entire image into consideration, and produces an orientation-dependent and long-range interaction between two images to drive the registration process. This property of interaction endows the new registration framework with both fast convergence rate and high registration accuracy. Moreover, the new energy function can be adapted to realize symmetric diffeomorphic transformation so as to ensure one-to-one matching between subjects. In this paper, the superiority of the new method is theoretically proven, experimentally tested and compared with the state-of-the-art SyN method. Experimental results with 3-D magnetic resonance brain images demonstrate that the proposed method outperforms the compared methods in terms of both registration accuracy and computation time.

  14. Dislocation mediated alignment during metal nanoparticle coalescence

    DOE PAGES

    Lange, A. P.; Samanta, A.; Majidi, H.; ...

    2016-09-13

    Dislocation mediated alignment processes during gold nanoparticle coalescence were studied at low and high temperatures using molecular dynamics simulations and transmission electron microscopy. Particles underwent rigid body rotations immediately following attachment in both low temperature (500 K) simulated coalescence events and low temperature (~315 K) transmission electron microscopy beam heating experiments. In many low temperature simulations, some degree of misorientation between particles remained after rigid body rotations, which was accommodated by grain boundary dislocation nodes. These dislocations were either sessile and remained at the interface for the duration of the simulation or dissociated and cross-slipped through the adjacent particles, leadingmore » to improved co-alignment. Minimal rigid body rotations were observed during or immediately following attachment in high temperature (1100 K) simulations, which is attributed to enhanced diffusion at the particles' interface. However, rotation was eventually induced by {111} slip on planes parallel to the neck groove. These deformation modes led to the formation of single and multi-fold twins whose structures depended on the initial orientation of the particles. The driving force for {111} slip is attributed to high surface stresses near the intersection of low energy {111} facets in the neck region. The details of this twinning process were examined in detail using simulated trajectories, and the results reveal possible mechanisms for the nucleation and propagation of Shockley partials on consecutive planes. Deformation twinning was also observed in-situ using transmission electron microscopy, which resulted in the co-alignment of a set of the particles' {111} planes across their grain boundary and an increase in their dihedral angle. As a result, this constitutes the first detailed experimental observation of deformation twinning during nanoparticle coalescence, validating simulation results

  15. ACS CCDs daily monitor

    NASA Astrophysics Data System (ADS)

    Sirianni, Marco

    2006-07-01

    This program consists of a set of basic tests to monitor, the read noise, thedevelopment of hot pixels and test for any source of noise in ACS CCDdetectors. The files, biases and dark will be used to create referencefiles for science calibration. This programme will be for the entire lifetime of ACS.For cycle 15 the program will cover 18 months 12.1.06->05.31.08and it has been divied into three different proposal each covering six months.The three poroposal are 11041-11042-11043.

  16. ac bidirectional motor controller

    NASA Technical Reports Server (NTRS)

    Schreiner, K.

    1988-01-01

    Test data are presented and the design of a high-efficiency motor/generator controller at NASA-Lewis for use with the Space Station power system testbed is described. The bidirectional motor driver is a 20 kHz to variable frequency three-phase ac converter that operates from the high-frequency ac bus being designed for the Space Station. A zero-voltage-switching pulse-density-modulation technique is used in the converter to shape the low-frequency output waveform.

  17. Treatment of Medial Epicondyle Fracture without Associated Elbow Dislocation in Older Children and Adolescents

    PubMed Central

    Park, Kun Bo

    2012-01-01

    Purpose Displaced medial humeral epicondyle fractures with or without elbow dislocation have been treated with open reduction and fixation using K-wires or screws. The purpose of this study is to evaluate the clinical and radiological outcomes of surgical treatments of medial humeral epicondyle fracture without elbow dislocation according to the fixation methods. Materials and Methods Thirty-one patients who had undergone open reduction and fixation of the displaced medial humeral epicondyle fracture without elbow dislocation were included. Group I consisted of 21 patients who underwent fixation with K-wires, and Group II comprised 10 patients who underwent fixation with cannulated screws. Immediate postoperative, final follow-up and normal anteroposterior radiographs were compared and the clinical outcome was assessed using the final Japanese Orthopaedic Association (JOA) elbow assessment score. Results On the immediate postoperative radiographs, the distal humeral width in Group II was larger than that in Group I. On the final follow-up radiographs, the epicondylar position in Group I was lower than that in Group II. There was no significant difference in the distal humeral width, epicondylar position and joint space tilt between the immediate postoperative, final follow-up radiographs and the normal side within each group. There was no significant difference in the final JOA score between groups. Conclusion Open reduction followed by K-wire fixation or screw fixation of the displaced medial humeral epicondyle fracture without elbow dislocation in older children and adolescents resulted in improved radiologic outcome and good elbow function in spite of diverse radiologic deformities. PMID:23074121

  18. 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.

  19. Palmar divergent dislocation of scaphoid and lunate.

    PubMed

    Kang, Ho-Jung; Shim, Dong-Joon; Hahn, Soo-Bong; Kang, Eung-Shick

    2003-12-30

    A 28-year-old man presented with a palmar divergent dislocation of the scaphoid and lunate. He was treated with an open reduction and an internal fixation with two Kirschner's wires after the 25th day of trauma due to a neurological injury. The results were satisfactory after 18 months follow up without any evidence of avascular necrosis and traumatic arthritis of the scaphoid and lunate. The patient had no limitation in motion or intermittent wrist pain. We reported this case with a brief review of relevant literatures.

  20. Mechanical of Cracks Screened by Dislocations

    DTIC Science & Technology

    1982-01-01

    En principe, on peut obtenir un crittre de rupture totale en prbcisant )a condition locale de clivage sur Ia fissure et la r6sistance du r ~ seau sur...DislocationsRerit G. PERFORMING ORG. REPORT NUMBER ____ ___ ___ ___ _ ___ ___ ___ ____ ___ ___ ___ N/A V. AUT04ORWs CONRAC OR GRANT’ NUMBER(s) R . Ii...Thomson, J. E. Sinclair ARO 36-82 9. PERFORMING ORZANIZATIOha NAME AND ADDRESS r 0. PRPQ;RAM ELEMENT. PROjECT. TASK National Bureau of Standards AE OKUI

  1. Nonacute Treatment of Elbow Fracture with Persistent Ulnohumeral Dislocation or Subluxation.

    PubMed

    Chen, Neal C; Jupiter, Jesse B; Steinmann, Scott P; Ring, David

    2014-08-06

    ➤ There are patterns of traumatic elbow instability that help a surgeon to anticipate which structures are injured.➤ Patients treated for persistent subluxation or dislocation of the elbow more than two weeks after injury regain less motion and experience more adverse events.➤ The primary goal of treatment is stable reduction of the ulnohumeral joint and functional elbow motion.➤ Motion and pain are affected by contracture and scarring of the soft tissues, malalignment of the joint, fracture malunion, damage to the articular surface, and ulnar neuropathy.➤ Biomechanical and clinical studies support treatment with radial head arthroplasty and/or coronoid reconstruction for patients who have osseous insufficiency.

  2. 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.

  3. Symposium introduction: the first joint American Chemical Society Agricultural and Food Chemistry Division and the American Chemical Society International Chemical Sciences Chapter in Thailand

    Technology Transfer Automated Retrieval System (TEKTRAN)

    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 ...

  4. Ceramic joints

    DOEpatents

    Miller, Bradley J.; Patten, Jr., Donald O.

    1991-01-01

    Butt joints between materials having different coefficients of thermal expansion are prepared having a reduced probability of failure of stress facture. This is accomplished by narrowing/tapering the material having the lower coefficient of thermal expansion in a direction away from the joint interface and not joining the narrow-tapered surface to the material having the higher coefficient of thermal expansion.

  5. AC/DC converter

    NASA Astrophysics Data System (ADS)

    Jain, Praveen K.

    1992-08-01

    In a system such as a 20 kHz space station primary electrical power distribution system, power conversion from AC to DC is required. Some of the basic requirements for this conversion are high efficiency, light weight and small volume, regulated output voltage, close to unity input power factor, distortionless input current, soft-starting, low electromagnetic interference, and high reliability. An AC-to-DC converter is disclosed which satisfies the main design objectives of such converters for use in space. The converter of the invention comprises an input transformer, a resonant network, a current controller, a diode rectifier, and an output filter. The input transformer is for connection to a single phase, high frequency, sinusoidal waveform AC voltage source and provides a matching voltage isolating from the AC source. The resonant network converts this voltage to a sinusoidal, high frequency bidirectional current output, which is received by the current controller to provide the desired output current. The diode rectifier is connected in parallel with the current controller to convert the bidirectional current into a unidirectional current output. The output filter is connected to the rectifier to provide an essentially ripple-free, substantially constant voltage DC output.

  6. AC/RF Superconductivity

    SciTech Connect

    Ciovati, Gianluigi

    2015-02-01

    This contribution provides a brief introduction to AC/RF superconductivity, with an emphasis on application to accelerators. The topics covered include the surface impedance of normal conductors and superconductors, the residual resistance, the field dependence of the surface resistance, and the superheating field.

  7. Fracture-dislocation of the humeral condyles in adults: results of surgical treatment.

    PubMed

    Bentounsi, Abdelhakim

    2015-09-01

    Fracture-dislocation of the humeral condyle is exceptional in adults. The purpose was to analyze the results of surgical treatment by open reduction and internal fixation without ligamentous repair. There were six men with an average age of 31 years. According to the AO classification, five fractures were classified as AO type B1 and one as B2. Dislocation was reduced in emergency before osteosynthesis. Postoperatively, the joint was held immobile with a brace for 25.40 days. Five patients were reviewed after a mean follow-up of 52.96 months. The median arc of flexion/extension was 104.80° and 157.8° for pronation-supination. All elbows were stable and all fractures were consolidated. Two elbows were painful. The results were satisfactory in five patients. The elbow stability can be ensured only by the synthesis of bone structures. Surgical treatment should restore exact anatomy between the condyle and trochlea. This protocol may provide a joint stability and satisfactory results.

  8. Neglected surgically intervened bilateral congenital dislocation of knee in an adolescent

    PubMed Central

    Kumar, Jaswant; Dhammi, Ish Kumar; Jain, Anil K

    2014-01-01

    Neglected bilateral congenital dislocation of knee is unusual. A 12 year old boy presented with inability to walk due to buckling of the knee. The symptoms were present since the child learnt walking. He preferred not to walk. Bilateral supracondylar femoral osteotomy was done at the age of 6 years. Patient had a fixed flexion deformity of both knees, 30° in the right (range of flexion from 30° to 45°) and 45° fixed flexion deformity in left knee respectively (range of flexion from 45° to 65°) when presented to us. The radiological examination revealed bilateral congenital dislocation of knee (CDK). No syndromic association was observed. He was planned for staged treatment. In stage I, the knee joints were distracted by Ilizarov ring fixators and this was followed by open reduction of both the knee joints in stage II. A bilateral supracondylar extension osteotomy was done 18 months after the previous surgery (stage III). The final followup visit at 4 years the patient presented with range of motion 5-100° and 5-80° on the right and left knee respectively with good functional outcome. The case is reported in view of lack of treatment guidelines for long standing neglected CDK in an adolescent child. PMID:24600070

  9. Concept of healing of recurrent shoulder dislocation.

    PubMed

    D'Angelo, Donato

    2014-01-01

    This paper presents the main surgical techniques applied in the treatment of anterior recurrent shoulder dislocation, aiming the achievement of the normality of articulate movements. This was obtained by combining distinct surgical procedures, which allowed the recovery of a complete functional capacity of the shoulder, without jeopardizing the normality of movement, something that has not been recorded in the case of the tense sutures of the surgical procedures of Putti-Platt, Bankart, Latarjet, Dickson-O'Dell and others. The careful review of the methods applied supports the conclusion that recurrent shoulder dislocation can be cured, since cure has been obtained in 97% of the treated cases. However, some degree of limitation in the shoulder movement has been observed in most of the treated cases. Our main goal was to achieve a complete shoulder functional recovery, by treating simultaneously all of the anatomical-pathological lesions, without considering the so-called essential lesions. The period of post-operatory immobilization only last for the healing of soft parts; this takes place in a position of neutral shoulder rotation, since the use of vascular bone graft eliminates the need for long time immobilization, due to the shoulder stabilization provided by rigid fixation of the coracoid at the glenoid edge, as in the Latarjet's technique. Our procedure, used since 1959, comprises the association of several techniques, which has permitted shoulder healing without movement limitation. That was because of the tension reduction in the sutures of the subescapularis, capsule, and coracobraquialis muscles.

  10. Implicit integration methods for dislocation dynamics

    NASA Astrophysics Data System (ADS)

    Gardner, D. J.; Woodward, C. S.; Reynolds, D. R.; Hommes, G.; Aubry, S.; Arsenlis, A.

    2015-03-01

    In dislocation dynamics simulations, strain hardening simulations require integrating stiff systems of ordinary differential equations in time with expensive force calculations, discontinuous topological events and rapidly changing problem size. Current solvers in use often result in small time steps and long simulation times. Faster solvers may help dislocation dynamics simulations accumulate plastic strains at strain rates comparable to experimental observations. This paper investigates the viability of high-order implicit time integrators and robust nonlinear solvers to reduce simulation run times while maintaining the accuracy of the computed solution. In particular, implicit Runge-Kutta time integrators are explored as a way of providing greater accuracy over a larger time step than is typically done with the standard second-order trapezoidal method. In addition, both accelerated fixed point and Newton's method are investigated to provide fast and effective solves for the nonlinear systems that must be resolved within each time step. Results show that integrators of third order are the most effective, while accelerated fixed point and Newton's method both improve solver performance over the standard fixed point method used for the solution of the nonlinear systems.

  11. Implicit integration methods for dislocation dynamics

    DOE PAGES

    Gardner, D. J.; Woodward, C. S.; Reynolds, D. R.; ...

    2015-01-20

    In dislocation dynamics simulations, strain hardening simulations require integrating stiff systems of ordinary differential equations in time with expensive force calculations, discontinuous topological events, and rapidly changing problem size. Current solvers in use often result in small time steps and long simulation times. Faster solvers may help dislocation dynamics simulations accumulate plastic strains at strain rates comparable to experimental observations. Here, this paper investigates the viability of high order implicit time integrators and robust nonlinear solvers to reduce simulation run times while maintaining the accuracy of the computed solution. In particular, implicit Runge-Kutta time integrators are explored as a waymore » of providing greater accuracy over a larger time step than is typically done with the standard second-order trapezoidal method. In addition, both accelerated fixed point and Newton's method are investigated to provide fast and effective solves for the nonlinear systems that must be resolved within each time step. Results show that integrators of third order are the most effective, while accelerated fixed point and Newton's method both improve solver performance over the standard fixed point method used for the solution of the nonlinear systems.« less

  12. Implicit integration methods for dislocation dynamics

    SciTech Connect

    Gardner, D. J.; Woodward, C. S.; Reynolds, D. R.; Hommes, G.; Aubry, S.; Arsenlis, A.

    2015-01-20

    In dislocation dynamics simulations, strain hardening simulations require integrating stiff systems of ordinary differential equations in time with expensive force calculations, discontinuous topological events, and rapidly changing problem size. Current solvers in use often result in small time steps and long simulation times. Faster solvers may help dislocation dynamics simulations accumulate plastic strains at strain rates comparable to experimental observations. Here, this paper investigates the viability of high order implicit time integrators and robust nonlinear solvers to reduce simulation run times while maintaining the accuracy of the computed solution. In particular, implicit Runge-Kutta time integrators are explored as a way of providing greater accuracy over a larger time step than is typically done with the standard second-order trapezoidal method. In addition, both accelerated fixed point and Newton's method are investigated to provide fast and effective solves for the nonlinear systems that must be resolved within each time step. Results show that integrators of third order are the most effective, while accelerated fixed point and Newton's method both improve solver performance over the standard fixed point method used for the solution of the nonlinear systems.

  13. Reprint of: Dynamics of discrete screw dislocations on glide directions

    NASA Astrophysics Data System (ADS)

    Alicandro, R.; De Luca, L.; Garroni, A.; Ponsiglione, M.

    2016-12-01

    We consider a simple discrete model for screw dislocations in crystals. Using a variational discrete scheme we study the motion of a configuration of dislocations toward low energy configurations. We deduce an effective fully overdamped dynamics that follows the maximal dissipation criterion introduced in Cermelli and Gurtin (1999) and predicts motion along the glide directions of the crystal.

  14. Effective mobility of dislocations from systematic coarse-graining

    NASA Astrophysics Data System (ADS)

    Kooiman, M.; Hütter, M.; Geers, MGD

    2015-06-01

    The dynamics of large amounts of dislocations governs the plastic response of crystalline materials. In this contribution we discuss the relation between the mobility of discrete dislocations and the resulting flow rule for coarse-grained dislocation densities. The mobilities used in literature on these levels are quite different, for example in terms of their intrinsic the stress dependence. To establish the relation across the scales, we have derived the macroscopic evolution equations of dislocation densities from the equations of motion of individual dislocations by means of systematic coarse-graining. From this, we can identify a memory kernel relating the driving force and the flux of dislocations. This kernel can be considered as an effective macroscopic mobility with two contributions; a direct contribution related to the overdamped motion of individual dislocations, and an emergent contribution that arises from time correlations of fluctuations in the Peach-Koehler force. Scaling analysis shows that the latter contribution is dominant for dislocations in metals at room temperature. We also discuss several concerns related to the separation of timescales.

  15. A field theory of piezoelectric media containing dislocations

    SciTech Connect

    Taupin, V. Fressengeas, C.; Ventura, P.; Lebyodkin, M.

    2014-04-14

    A field theory is proposed to extend the standard piezoelectric framework for linear elastic solids by accounting for the presence and motion of dislocation fields and assessing their impact on the piezoelectric properties. The proposed theory describes the incompatible lattice distortion and residual piezoelectric polarization fields induced by dislocation ensembles, as well as the dynamic evolution of these fields through dislocation motion driven by coupled electro-mechanical loading. It is suggested that (i) dislocation mobility may be enhanced or inhibited by the electric field, depending on the polarity of the latter, (ii) plasticity mediated by dislocation motion allows capturing long-term time-dependent properties of piezoelectric polarization. Due to the continuity of the proposed electro-mechanical framework, the stress/strain and polarization fields are smooth even in the dislocation core regions. The theory is applied to gallium nitride layers for validation. The piezoelectric polarization fields associated with bulk screw/edge dislocations are retrieved and surface potential modulations are predicted. The results are extended to dislocation loops.

  16. Dynamics of discrete screw dislocations on glide directions

    NASA Astrophysics Data System (ADS)

    Alicandro, R.; De Luca, L.; Garroni, A.; Ponsiglione, M.

    2016-07-01

    We consider a simple discrete model for screw dislocations in crystals. Using a variational discrete scheme we study the motion of a configuration of dislocations toward low energy configurations. We deduce an effective fully overdamped dynamics that follows the maximal dissipation criterion introduced in Cermelli and Gurtin (1999) and predicts motion along the glide directions of the crystal.

  17. Multiscale characterization of dislocation processes in Al 5754

    NASA Astrophysics Data System (ADS)

    Kacher, Josh; Mishra, Raja K.; Minor, Andrew M.

    2015-07-01

    Multiscale characterization was performed on an Al-Mg alloy, Al 5754 O-temper, including in situ mechanical deformation in both the scanning electron microscope and the transmission electron microscope. Scanning electron microscopy characterization showed corresponding inhomogeneity in the dislocation and Mg distribution, with higher levels of Mg correlating with elevated levels of dislocation density. At the nanoscale, in situ transmission electron microscopy straining experiments showed that dislocation propagation through the Al matrix is characterized by frequent interactions with obstacles smaller than the imaging resolution that resulted in the formation of dislocation debris in the form of dislocation loops. Post-mortem chemical characterization and comparison to dislocation loop behaviour in an Al-Cr alloy suggests that these obstacles are small Mg clusters. Previous theoretical work and indirect experimental evidence have suggested that these Mg nanoclusters are important factors contributing to strain instabilities in Al-Mg alloys. This study provides direct experimental characterization of the interaction of glissile dislocations with these nanoclusters and the stress needed for dislocations to overcome them.

  18. 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.

  19. Simultaneous bilateral elbow dislocation in an international gymnast

    PubMed Central

    Syed, A. A.; O'Flanagan, J.

    1999-01-01

    Elbow dislocation is a rare injury in elite athletes. We report an unusual case of simultaneous bilateral elbow dislocations with a unilateral radial head fracture in an international female athlete competing on the asymmetrical bars. These injuries require prompt reduction and immediate mobilisation if an abrupt end to a promising career is to be prevented. 




 PMID:10205699

  20. Method to reduce dislocation density in silicon using stress

    DOEpatents

    Buonassisi, Anthony; Bertoni, Mariana; Argon, Ali; Castellanos, Sergio; Fecych, Alexandria; Powell, Douglas; Vogl, Michelle

    2013-03-05

    A crystalline material structure with reduced dislocation density and method of producing same is provided. The crystalline material structure is annealed at temperatures above the brittle-to-ductile transition temperature of the crystalline material structure. One or more stress elements are formed on the crystalline material structure so as to annihilate dislocations or to move them into less harmful locations.

  1. Computation of the lattice Green function for a dislocation

    NASA Astrophysics Data System (ADS)

    Tan, Anne Marie Z.; Trinkle, Dallas R.

    2016-08-01

    Modeling isolated dislocations is challenging due to their long-ranged strain fields. Flexible boundary condition methods capture the correct long-range strain field of a defect by coupling the defect core to an infinite harmonic bulk through the lattice Green function (LGF). To improve the accuracy and efficiency of flexible boundary condition methods, we develop a numerical method to compute the LGF specifically for a dislocation geometry; in contrast to previous methods, where the LGF was computed for the perfect bulk as an approximation for the dislocation. Our approach directly accounts for the topology of a dislocation, and the errors in the LGF computation converge rapidly for edge dislocations in a simple cubic model system as well as in BCC Fe with an empirical potential. When used within the flexible boundary condition approach, the dislocation LGF relaxes dislocation core geometries in fewer iterations than when the perfect bulk LGF is used as an approximation for the dislocation, making a flexible boundary condition approach more efficient.

  2. Dislocation Mechanism of Twinning in Ni-Mn-Ga

    NASA Astrophysics Data System (ADS)

    Zárubová, N.; Ge, Y.; Gemperlová, J.; Gemperle, A.; Hannula, S.-P.

    2012-03-01

    Tensile tests were performed in situ in a transmission electron microscope to investigate the twinning mechanism in non-modulated Ni-Mn-Ga martensite. The reorientation of the twin variants occurs via twinning dislocations. Their generation and movement were followed; the glide plane and Burgers vector were verified. Individual twinning dislocations were visualized.

  3. 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.

  4. The Dislocated Worker: When Training Is Not Enough.

    ERIC Educational Resources Information Center

    Blong, John T.; Shultz, Rose M.

    1990-01-01

    Discusses the socioeconomic effects of plant closings, focusing on the problems faced by dislocated workers who lack the financial resources to complete a retraining program. Describes the Eastern Iowa Community College District's efforts to train and counsel dislocated workers through its Caterpillar Worker Assistance Center. (DMM)

  5. Collective Dislocation Dynamics and Avalanches during Fatigue of Aluminum

    NASA Astrophysics Data System (ADS)

    Rhouma, W. Ben; Deschanel, S.; Weiss, J.

    2011-09-01

    We present a study of collective dislocation dynamics and plasticity during fatigue of pure Aluminum from the analysis of continuous and discrete acoustic emission (AE). The three stages of macroscopic fatigue behavior (strain-hardening, shakedown, and strain softening) are clearly differentiated in terms of AE. During the first loading cycles, collective dislocation dynamics consists in dislocation avalanches of various sizes and clustered in time. Once a microstructure of dislocation cells and walls is formed, the spreading of such avalanches is restrained, and the discrete AE strongly decreases. Instead, a symmetrical (tension-compression) continuous AE, maximal at plastic yield, is observed, likely associated to a superposition of numerous, small and uncorrelated motions such as dislocation loops initiation from cell walls. However, some discrete AE activity remains during shakedown, a possible signature of sudden rearrangements of the microstructure occurring at scales larger than its wavelength. Finally, the onset of strain softening is associated to a strong increase of discrete AE, in relation with microcracking. Our results suggest that collective dislocation instabilities and the emergence of a dislocation microstructure are interrelated, and challenge future numerical modeling developments of dislocation assemblies.

  6. 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

  7. Dislocation core reconstruction induced by carbon segregation in bcc iron

    NASA Astrophysics Data System (ADS)

    Ventelon, Lisa; Lüthi, B.; Clouet, E.; Proville, L.; Legrand, B.; Rodney, D.; Willaime, F.

    2015-06-01

    The relative stability of dislocation core configurations in body-centered-cubic metals is profoundly modified by the presence of solutes. Considering the Fe(C) system, we demonstrate by using density functional theory that carbon atoms destabilize the usual easy core to the benefit of the hard core configuration of the screw dislocation, which is unstable in pure metals. The carbon atom is at the center of a regular prism in a cementitelike local environment. The same dislocation core reconstruction is also found with other solutes (B, N, O) and in W(C). This unexpected low-energy configuration induces a strong solute-dislocation attraction, leading to dislocation core saturation by solute atoms, even for very low bulk solute concentrations. This core reconstruction will constitute an essential factor to account for in solute-segregation related phenomena, such as strain aging.

  8. 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.

  9. Self-force on dislocation segments in anisotropic crystals.

    PubMed

    Fitzgerald, S P; Aubry, S

    2010-07-28

    A dislocation segment in a crystal experiences a 'self-force', by virtue of the orientation dependence of its elastic energy. If the crystal is elastically isotropic, this force is manifested as a couple acting to rotate the segment toward the lower energy of the pure screw orientation (i.e. acting to align the dislocation line with its Burgers vector). If the crystal is anisotropic, there are additional contributions to the couple, arising from the more complex energy landscape of the lattice itself. These effects can strongly influence the dynamic evolution of dislocation networks, and via their governing role in dislocation multiplication phenomena, control plastic flow in metals. In this paper we develop a model for dislocation self-forces in a general anisotropic crystal, and briefly consider the technologically important example of α-iron, which becomes increasingly anisotropic as the temperature approaches that of the α-γ phase transition at 912 °C.

  10. Room-temperature dislocation climb in copper-niobium interfaces

    SciTech Connect

    Wang, Jian; Hoagland, Richard G; Hirth, John P; Misra, Amit

    2008-01-01

    Using atomistic simulations, we show that dislocations climb efficiently in metallic copper-niobium interfaces through absorption and emission of vacancies in the dislocation core, as well as an associated counter diffusion of Cu atoms in the interfacial plane. The high efficiency of dislocation climb in the interface is ascribed to the high vacancy concentration of 0.05 in the interfacial plane, the low formation energy of 0.12 e V with respect to removal or insertion of Cu atoms, as well as the low kinetic barrier of 0.10 eV for vacancy migration in the interfacial Cu plane. Dislocation climb in the interface facilitates reactions of interfacial dislocations, and enables interfaces to be in the equilibrium state with respect to concentrations ofpoint defects.

  11. 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.

  12. An olecranon chondral flap and osteochondral coronoid fracture in a spontaneously reduced elbow dislocation in a child.

    PubMed

    Quick, Tom J; Gibbons, Paul; Smith, Nick

    2013-09-01

    Elbow injuries in children are very common and radiographs are often difficult to interpret because of the radiolucency of the cartilaginous anlage and the progressive appearance of multiple secondary ossification centres. Elbow dislocations are rare injuries in children. Coronoid fractures can occur during dislocation or relocation of the elbow and can be the only hallmark of a severe injury. The understanding of the mechanics of these injuries has undergone considerable evolution over the past decade. Intra-articular chondral flap fractures are a traumatic elevation of the hyaline cartilage from the subchondral bone. They are also rare injuries in children but should be included in the differential when examining an injured joint. The infrequency of these injuries provides little opportunity to become accustomed to the radiographic signs. We present a case report of a 4-year-old boy with both an olecranon chondral flap and coronoid cartilaginous fracture after a joint dislocation. We present his plain radiography and MRI with illustrated photographic records of the operative findings. This injury has been little described in the literature and never with such imaging to aid understanding of both the pathology and the injury mechanism.

  13. 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…

  14. Reactions between a <111> screw dislocation and <100> interstitial dislocation loops in alpha-iron modelled at atomic-scale

    SciTech Connect

    Terentyev, Dmitry; Bacon, David J; Osetskiy, Yury N

    2010-03-01

    Interstitial dislocation loops with Burgers vector of <100> type are observed in {alpha}-iron irradiated by neutrons or heavy ions, and their population increases with increasing temperature. Their effect on motion of a 1/2<111> edge dislocation was reported earlier 1. Results are presented of a molecular dynamics study of interactions between a 1/2<111> screw dislocation and <100> loops in iron at temperature in the range 100 to 600 K. A variety of reaction mechanisms and outcomes are observed and classified in terms of the resulting dislocation configuration and the maximum stress required for the dislocation to break away. The highest obstacle resistance arises when the loop is absorbed to form a helical turn on the screw dislocation line, for the dislocation cannot glide away until the turn closes and a loop is released with the same Burgers vector as the line. Other than one situation found, in which no dislocation-loop reaction occurs, the weakest obstacle strength is found when the original <100> loop is restored at the end of the reaction. The important role of the cross-slip and the influence of model boundary conditions are emphasised and demonstrated by examples.

  15. Worker Dislocation: A Policy Study and Selected References on Worker Dislocation and the Unemployment Process. An Annotated Bibliography.

    ERIC Educational Resources Information Center

    Clark, Marilyn; And Others

    Dislocated workers are distinguished from chronically unemployed individuals in that the former have a stable work history and are generally unaware of the community's social services programs and how to use them. Dislocated workers frequently lack job search skills and do not see the transferability of their work skills. Often, they have heavy…

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

    SciTech Connect

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

    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 CP 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.

  17. 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

  18. Compliant joint

    NASA Technical Reports Server (NTRS)

    Eklund, Wayne D. (Inventor); Kerley, James J. (Inventor)

    1990-01-01

    A compliant joint is provided for prosthetic and robotic devices which permits rotation in three different planes. The joint provides for the controlled use of cable under motion. Perpendicular outer mounting frames are joined by swaged cables that interlock at a center block. Ball bearings allow for the free rotation of the second mounting frame relative to the first mounting frame within a predetermined angular rotation that is controlled by two stop devices. The cables allow for compliance at the stops and the cables allow for compliance in six degrees of freedom enabling the duplication or simulation of the rotational movement and flexibility of a natural hip or knee joint, as well as the simulation of a joint designed for a specific robotic component for predetermined design parameters.

  19. Joint Commission

    MedlinePlus

    Skip to main content The Joint Commission Log In | Request Guest Access Forgot password? | Log In Help Contact Us | Careers | JCR Web Store | Press Room Search Home Accreditation Accreditation Ambulatory Health ...

  20. 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.

  1. Transient vascular compromise of the lunate after fracture-dislocation or dislocation of the carpus.

    PubMed

    White, R E; Omer, G E

    1984-03-01

    Although classic avascular necrosis of the lunate is rare after fracture-dislocation or dislocation of the carpus, these severe carpal injuries can compromise the vascular supply of the lunate. The lunate thus develops a relative increase in radiodensity. Our finding of an incidence of 12.5%--three of 24 cases--suggests a relatively frequent occurrence. The clinical course was transient with resolution of abnormal radiodensity and subjective findings. Moreover, none of the three cases progressed to classic avascular necrosis of the lunate, Kienböck's disease. The clinician should not confuse this transient vascular compromise of the lunate with Kienböck's disease, but should be aware of the entity and its benign, self-limited course and should treat it expectantly.

  2. Infected shoulder joint with loose Suture Anchor in the joint after Bankart’s Repair- A Case Report

    PubMed Central

    Kumar, Mukesh; Thilak, Jai

    2016-01-01

    Introduction: The glenoid labrum is frequently torn in traumatic glenohumeral dislocation; arthroscopic repair is the standard method of treatment. The complications associated with this repair are pulling out of metal suture anchors, chondrolysis and joint infection. The infection of joint after arthroscopy is less than 1%. Staphylococcus is most common organism and rarely followed by Pseudomonas aeruginosa. We report a case of infected shoulder with chondrolysis of the joint and pulled out metal suture anchor lying inside the joint after Bankart’s repair. Case Report: A 22-year-old gentleman came to us with complaints of shoulder joint pain & gross restriction of movements for one year, with history of intermittent fever and treatment in nearby hospital. He also gives past history of recurrent dislocation of shoulder with last episode 18 months back, which was diagnosed as Bankart’s lesion and arthroscopic Bankart’s repair was done 15 months back. He was evaluated at our institute and suspected to have infection of shoulder joint with pulled out metal suture anchor inside the joint. Arthroscopic removal of suture anchor and debridement of shoulder joint was done, Culture was obtained and culture specific antibiotics were given for six weeks, and significant improvement was observed with this line of treatment. At lyear follow up, the patient was able to perform his daily activities with terminal restriction of range of motion. Conclusions: Shoulder joint infection is rare after Bankart’s repair and required a high degree of suspicion. Any foreign materials inside the joint should be taken out & followed with aggressive treatment by debridement, irrigation and culture specific antibiotics. Suppression of joint infection with antibiotics should be avoided specially when there is foreign body inside the joint. PMID:27703928

  3. Competing Processes in Reactions between an Edge Dislocation and Dislocation Loops in a Body-Centred Cubic Metal

    SciTech Connect

    Terentyev, Dmitry; Bacon, David J; Osetskiy, Yury N

    2010-01-01

    Molecular dynamics simulation was used to investigate reactions of a 1/2<111>{l_brace}110{r_brace} edge dislocation with interstitial dislocation loops of 1/2<111> and <100> type in a model of iron. Whether loops are strong or weak obstacles depends not only on loop size and type, but also on temperature and dislocation velocity. These parameters determine whether a loop is absorbed on the dislocation or left behind as it glides away. Absorption requires glide of a reaction segment over the loop surface and cross-slip of dipole dislocation arms attached to the ends of the segment: these mechanisms depend on temperature and strain rate, as discussed here.

  4. Stress-free states of continuum dislocation fields: Rotations, grain boundaries, and the Nye dislocation density tensor

    NASA Astrophysics Data System (ADS)

    Limkumnerd, Surachate; Sethna, James P.

    2007-06-01

    We derive general relations between grain boundaries, rotational deformations, and stress-free states for the mesoscale continuum Nye dislocation density tensor. Dislocations generally are associated with long-range stress fields. We provide the general form for dislocation density fields whose stress fields vanish. We explain that a grain boundary (a dislocation wall satisfying Frank’s formula) has vanishing stress in the continuum limit. We show that the general stress-free state can be written explicitly as a (perhaps continuous) superposition of flat Frank walls. We show that the stress-free states are also naturally interpreted as configurations generated by a general spatially dependent rotational deformation. Finally, we propose a least-squares definition for the spatially dependent rotation field of a general (stressful) dislocation density field.

  5. Kink pair production and dislocation motion

    PubMed Central

    Fitzgerald, S. P.

    2016-01-01

    The motion of extended defects called dislocations controls the mechanical properties of crystalline materials such as strength and ductility. Under moderate applied loads, this motion proceeds via the thermal nucleation of kink pairs. The nucleation rate is known to be a highly nonlinear function of the applied load, and its calculation has long been a theoretical challenge. In this article, a stochastic path integral approach is used to derive a simple, general, and exact formula for the rate. The predictions are in excellent agreement with experimental and computational investigations, and unambiguously explain the origin of the observed extreme nonlinearity. The results can also be applied to other systems modelled by an elastic string interacting with a periodic potential, such as Josephson junctions in superconductors. PMID:28004834

  6. Kink pair production and dislocation motion

    NASA Astrophysics Data System (ADS)

    Fitzgerald, S. P.

    2016-12-01

    The motion of extended defects called dislocations controls the mechanical properties of crystalline materials such as strength and ductility. Under moderate applied loads, this motion proceeds via the thermal nucleation of kink pairs. The nucleation rate is known to be a highly nonlinear function of the applied load, and its calculation has long been a theoretical challenge. In this article, a stochastic path integral approach is used to derive a simple, general, and exact formula for the rate. The predictions are in excellent agreement with experimental and computational investigations, and unambiguously explain the origin of the observed extreme nonlinearity. The results can also be applied to other systems modelled by an elastic string interacting with a periodic potential, such as Josephson junctions in superconductors.

  7. Painful Spastic Hip Dislocation: Proximal Femoral Resection

    PubMed Central

    Albiñana, Javier; Gonzalez-Moran, Gaspar

    2002-01-01

    The dislocated hip in a non-ambulatory child with spastic paresis tends to be a painful interference to sleep, sitting upright, and perineal care. Proximal femoral resection-interposition arthroplasty is one method of treatment for this condition. We reviewed eight hips, two bilateral cases, with a mean follow-up of 30 months. Clinical improvement was observed in all except one case, with respect to pain relief and sitting tolerance. Some proximal migration was observed in three cases, despite routine post-operative skeletal traction in all cases and careful soft tissue interposition. One case showed significant heterotopic ossification which restricted prolonged sitting. This patient needed some occasional medication for pain. PMID:12180614

  8. Disclinations, dislocations, and continuous defects: A reappraisal

    NASA Astrophysics Data System (ADS)

    Kleman, M.; Friedel, J.

    2008-01-01

    Disclinations were first observed in mesomorphic phases. They were later found relevant to a number of ill-ordered condensed-matter media involving continuous symmetries or frustrated order. Disclinations also appear in polycrystals at the edges of grain boundaries; but they are of limited interest in solid single crystals, where they can move only by diffusion climb and, owing to their large elastic stresses, mostly appear in close pairs of opposite signs. The relaxation mechanisms associated with a disclination in its creation, motion, and change of shape involve an interplay with continuous or quantized dislocations and/or continuous disclinations. These are attached to the disclinations or are akin to Nye’s dislocation densities, which are particularly well suited for consideration here. The notion of an extended Volterra process is introduced, which takes these relaxation processes into account and covers different situations where this interplay takes place. These concepts are illustrated by a variety of applications in amorphous solids, mesomorphic phases, and frustrated media in their curved habit space. These often involve disclination networks with specific node conditions. The powerful topological theory of line defects considers only defects stable against any change of boundary conditions or relaxation processes compatible with the structure considered. It can be seen as a simplified case of the approach considered here, particularly suited for media of high plasticity or/and complex structures. It cannot analyze the dynamical properties of defects nor the elastic constants involved in their static properties; topological stability cannot guarantee energetic stability, and sometimes cannot distinguish finer details of the structure of defects.

  9. The length change of a dislocation junction in FCC-single crystals under stress

    NASA Astrophysics Data System (ADS)

    Kurinnaya, Raisa; Zgolich, Marina; Starenchenko, Vladimir; Sadritdinova, Gulnora

    2016-01-01

    The product of dislocation reactions among dislocations of non-coplanar slip systems are dislocation junctions. The paper presents the study on the length change of dislocation junctions under stress. It is revealed that dislocation junctions can be destructed by merging of triple dislocation nodes at certain inclination angles of the glide dislocation and the forest dislocation to the junction line and the corresponding lengths of free segments of intersecting dislocations. Dislocation junctions formed at an arbitrary intersection of segments of the reacting dislocation are investigated. The geometry of the intersection of segments of reacting dislocations, at which dislocation junctions are not completely destructed under stress but cease to be an obstacle for further motion of the glide dislocation, is determined. Such junctions remain in the shear zone, presenting an obstacle to other glide dislocations. Conditions under which the length of the dislocation junction increases with an increase in the stress exceeding the original length are found. The formed extended barrier becomes too strong for the acting stress. Higher stresses are required in order to destruct it. The probability of completely destructible junctions under stress, the probability of non-destructible junctions that remain in the shear zone and replenish the density of dislocation debris, as well as the probability of formation of long strong junctions, which are barriers capable of limiting the shear zone, are determined.

  10. Surgical versus non-surgical management for primary patellar dislocations: an up-to-date meta-analysis.

    PubMed

    Zheng, Xiaozuo; Kang, Kai; Li, Tong; Lu, Bo; Dong, Jiangtao; Gao, Shijun

    2014-12-01

    The aim of this up-to-date meta-analysis was to compare the effects of surgical versus non-surgical treatment of patients following primary patellar dislocation and to provide the best evidence currently available. A comprehensive literature search was conducted using multiple databases, including Medline, Embase, and Cochrane Registry of Clinical Trials. All databases were searched from the earliest records to May 2013. Eligible studies were selected, and data were extracted by two independent investigators. The primary outcome variable was the frequency of recurrent patellar dislocation. The other outcomes included knee function scores, patient-rated outcomes, and radiographic examination. If appropriate, meta-analysis of these variables was performed. Nine independent trials were found to match the inclusion criteria. The pooled results demonstrated that the incidence of recurrent patellar dislocation and Hughston visual analog scale was significantly lower in the surgical treatment group than that in the non-surgical treatment group (P < 0.05). There was no statistically significant difference between the two treatment groups in frequency of subsequent surgical interventions, percentage of excellent or good subjective opinion, Kujala score, pain score on visual analog scale, and severity of patellofemoral joint osteoarthrosis (P > 0.05). This up-to-date meta-analysis indicates that surgical treatment was associated with a lower risk of recurrent patellar dislocation, but a lower Hughston VAS than non-surgical treatment for primary patellar dislocation. More large high-quality trials and further studies are needed to overcome the limitations of small sample sizes, and varieties of different surgical procedures or non-surgical management strategies adopted in the included trials.

  11. 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 104 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 1012 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-energy cellular dislocation structure becomemore » 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

  12. Period-doubling reconstructions of semiconductor partial dislocations

    DOE PAGES

    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° 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 significantly reduced;more » 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. Lastly, the competition between these dislocation phases suggests a new passivation strategy via population manipulation of the detrimental single-period phase.« less

  13. Period-doubling reconstructions of semiconductor partial dislocations

    SciTech Connect

    Park, Ji -Sang; Huang, Bing; Wei, Su -Huai; Kang, Joongoo; McMahon, William E.

    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° 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 significantly 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. Lastly, the competition between these dislocation phases suggests a new passivation strategy via population manipulation of the detrimental single-period phase.

  14. 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

  15. Spontaneous Late Intraocular Lens and Capsule Tension Ring Dislocation

    PubMed Central

    Koçak Altıntaş, Ayşe Gül; Omay, Aslıhan Esra; Çelik, Selda

    2017-01-01

    In this report, three cases with pseudoexfoliation (PEX) and advanced age with spontaneous intraocular lens (IOL) and capsule tension ring (CTR) dislocation were presented. All of our cases experienced progressive vision loss without an episode of strenuous physical activity, trauma, or any other ocular disease. Spontaneous dislocation was observed 2.5 to 8 years after uneventful phacosurgery. Each patient underwent complete IOL and CTR removal combined with anterior chamber IOL implantation. No complications were noticed during follow-up. As a result, capsule tension ring does not prevent late IOL dislocation after uncomplicated phacosurgery in the presence of PEX. Therefore, close follow-up is essential for patients with PEX.

  16. Dislocations in extruded Co-49.3 at. pct Al

    NASA Technical Reports Server (NTRS)

    Yaney, D. L.; Nix, W. D.; Pelton, A. R.

    1986-01-01

    Polycrystalline Co-49.3 at. pct Al, which had been extruded at 1505 K, was examined using transmission electron microscopy. Diffraction contrast analysis showed that b = 100 as well as b = 111 line dislocations contribute to elevated temperature deformation in CoAl. Therefore, it was concluded that sufficient slip systems exist in CoAl to allow for general plasticity in the absence of diffusional mechanisms. Line dislocations of the type b = 001 were observed on both 110 and 100 planes while b = 111 line dislocations were observed on 1 -1 0 planes.

  17. 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.

  18. Dynamic phases, pinning, and pattern formation for driven dislocation assemblies

    DOE PAGES

    Zhou, Caizhi; Reichhardt, Charles; Olson Reichhardt, Cynthia J.; ...

    2015-01-23

    We examine driven dislocation assemblies and show that they can exhibit a set of dynamical phases remarkably similar to those of driven systems with quenched disorder such as vortices in superconductors, magnetic domain walls, and charge density wave materials. These phases include pinned-jammed, fluctuating, and dynamically ordered states, and each produces distinct dislocation patterns as well as specific features in the noise fluctuations and transport properties. Lastly, our work suggests that many of the results established for systems with quenched disorder undergoing plastic depinning transitions can be applied to dislocation systems, providing a new approach for understanding pattern formation andmore » dynamics in these systems.« less

  19. Dynamic phases, pinning, and pattern formation for driven dislocation assemblies

    SciTech Connect

    Zhou, Caizhi; Reichhardt, Charles; Olson Reichhardt, Cynthia J.; Beyerlein, Irene J.

    2015-01-23

    We examine driven dislocation assemblies and show that they can exhibit a set of dynamical phases remarkably similar to those of driven systems with quenched disorder such as vortices in superconductors, magnetic domain walls, and charge density wave materials. These phases include pinned-jammed, fluctuating, and dynamically ordered states, and each produces distinct dislocation patterns as well as specific features in the noise fluctuations and transport properties. Lastly, our work suggests that many of the results established for systems with quenched disorder undergoing plastic depinning transitions can be applied to dislocation systems, providing a new approach for understanding pattern formation and dynamics in these systems.

  20. Simulation of the interaction between an edge dislocation and a 1 0 0 interstitial dislocation loop in -iron

    SciTech Connect

    Terentyev, Dmitry; Grammatikopoulos, P.; Bacon, D; Osetsky, Yu N

    2008-01-01

    Atomic-level simulations are used to investigate the interaction of an edge dislocation with h100i interstitial dislocation loops in airon at 300 K. Dislocation reactions are studied systematically for different loop positions and Burgers vector orientations, and results are compared for two different interatomic potentials. Reactions are wide-ranging and complex, but can be described in terms of conventional dislocation reactions in which Burgers vector is conserved. The fraction of interstitials left behind after dislocation breakaway varies from 25 to 100%. The nature of the reactions requiring high applied stress for breakaway is identified. The obstacle strengths of h100i loops, 1/2h111i loops and voids containing the same number (169) of point defects are compared. h100i loops with Burgers vector parallel to the dislocation glide plane are slightly stronger than h100i and 1/2h111i loops with inclined Burgers vector: voids are about 30% weaker than the stronger loops. However, small voids are stronger than small 1/2h111i loops. The complexity of some reactions and the variety of obstacle strengths poses a challenge for the development of continuum models of dislocation behaviour in irradiated iron. 2008 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

  1. The influence of the dislocation distribution heterogeneity degree on the formation of a non-misoriented dislocation cell substructures in f.c.c. metals

    NASA Astrophysics Data System (ADS)

    Cherepanov, D. N.; Selivanikova, O. V.; Matveev, M. V.

    2016-06-01

    Dislocation loops emitted by Frank-Reed source during crossing dislocations of the non-coplanar slip systems are accumulates jogs on the own dislocation line, resulting in the deceleration of the segments of dislocation loops with high jog density. As a result, bending around of the slowed segments the formation of dynamic dipoles in the shear zone occurs. In the present paper we consider formation mechanism of non-misoriented dislocation cell substructure during plastic deformation of f.c.c. metals and conclude that the increase in the degree heterogeneity of dislocation distribution leads to an increase in the jog density and reduce the mean value of arm dynamic dipoles.

  2. Primary repair of capsuloligamentous structures of trapeziometacarpal joint: A preliminary study

    PubMed Central

    Ansari, Mohammed Tahir; Kotwal, Prakash P.; Morey, Vivek Machhindra

    2014-01-01

    Background Isolated trapezio-metacarpal joint dislocation is uncommon and challenging since controversy still exists regarding its management. Description We present a short case series in which direct repair of trapezio-metacarpal ligaments was done in three patients who had isolated, unstable dislocation of the thumb carpometacarpal joint. All of them were engaged in tasks where no compromise in hand functions and grip strength was affordable. The dislocation was addressed primarily by repair of volar oblique and dorsoradial ligaments with suture anchors. The joint was immobilised in a cast for 4 weeks followed by gradual mobilisation. Results At an average follow up of 15 months, all the three patients have no restriction in the range of motion. There are no symptoms and signs of instability. In two patients, there is no pain at all; while one patient has occasional pain which is mild and does not interfere with the hand function. Radiographic examination showed normal joint alignment and no signs of subluxation or early osteoarthritis. Conclusion Repair of the capsuloligamentous complex with suture anchors may be considered as a treatment option in unstable trapezio-metacarpal joint dislocations in high demand patients. PMID:25983496

  3. Evolution of dislocation density and character in hot rolled titanium determined by X-ray diffraction

    SciTech Connect

    Dragomir, I.C. . E-mail: iuliana.cernatescu@mse.gatech.edu; Li, D.S.; Castello-Branco, G.A.; Garmestani, H.; Snyder, R.L.; Ribarik, G.; Ungar, T.

    2005-07-15

    X-ray Peak Profile Analysis was employed to determine the evolution dislocation density and dislocations type in hot rolled commercially pure titanium specimens. It was found that dislocation type is dominating the deformation mechanism at all rolling reduction levels studied here. A good agreement was found between the texture evolution and changes in dislocation slip system activity during the deformation process.

  4. [Traumatic vascular lesions of the knee joint].

    PubMed

    Markgraf, E; Clausner, G; Lungershausen, W

    1989-09-01

    The popliteal artery is a "critical" or key-artery, whose sudden occlusion leads to the ischemia-syndrome. The rate of amputation after missing or too late recovery is very high. The real time for the recovery runs to 3-6 hours. The reason for the injury of the vessel is the dorsal luxation of the knee-joint, the fracture of the lower thigh or the fracture of the tibial head with extreme dislocation of the fragments. The management of the diagnosis, the contents and the order of the surgical treatment are reported.

  5. Terrible triad elbow fracture-dislocation with triceps and flexor-pronator mass avulsion.

    PubMed

    Gajendran, Varun K; Bishop, Julius A

    2015-02-01

    Terrible triad elbow injuries, consisting of fractures of the radial head and coronoid with ulnohumeral dislocation, are challenging to treat. They require a comprehensive understanding of the complex anatomy of the elbow to effectively treat all of the pathology and create a stable, congruent joint. The authors present a case of a terrible triad injury with avulsion of the triceps and flexor-pronator mass after a low-energy fall in a young patient. Although most terrible triad fracture-dislocations can be successfully treated with coronoid fixation, radial head fixation or replacement, and repair of the lateral collateral ligament complex, this case involved a completely circumferential injury to the elbow. The coronoid and anterior capsule were disrupted anteriorly, the radial head and lateral collateral ligament complex were disrupted laterally, the triceps was disrupted posteriorly, and the flexor-pronator mass was disrupted medially. Although the authors prefer to address most terrible triad injuries through a lateral approach, they suspected a circumferential injury preoperatively and elected to use a single posterior incision to address all of the pathology conveniently. This injury required treatment of all disrupted structures, because the elbow remained unstable until the triceps and flexor-pronator mass avulsions were ultimately repaired. With any elbow fracture-dislocation, surgeons should look for evidence of additional injuries that do not fit the commonly described patterns, because they may necessitate modifications to the treatment plan. Given the relatively common complications of stiffness and instability despite modern surgical techniques, additional injuries may further compromise functional outcomes unless they are addressed properly.

  6. Lower Limbs Alignment in Patients with a Unilateral Completely Dislocated Hip

    PubMed Central

    Someya, Shinsuke; Sonohata, Motoki; Ide, Shuya; Nagamine, Satomi; Tajima, Tomonori; Mawatari, Masaaki

    2016-01-01

    Background: Severe hip osteoarthritis is known to lead to secondary osteoarthritis of the knee joint. It is not clear whether contracture or a leg length discrepancy is more important in determining the knee alignment. Methods: In this study, 48 hips in 48 patients with a unilateral completely dislocated hip (Crowe IV) were recruited. The patients were divided into two groups (Crowe IVa and IVb). The Crowe IVa group had completely dislocation with psudo-articulation, and the Crowe IVb group had completely dislocation without psudo-articulation. The lower limb alignment was divided into three patterns according to the femorotibial angle; varus (≥176 degrees), neutral(170 to 175 degrees) and valgus(≤169 degrees). Results: The combination of valgus alignment on the affected side and varus alignment on the unaffected side, so-called “windswept deformity” was observed in 12.5% of the patients; this included 18.2% and 7.7%, in the Crowe IVa and Crowe IVb groups, respectively. The valgus alignment on the unaffected side, namely “long leg arthropathy,” was found to have occurred in 6.3% of the patients, including 13.6% of the patients in the Crowe IVa group; there were no cases of long “leg arthropathy” in the Crowe IVb group. Conclusion: The lower limb alignment on the unaffected side had a tendency to be varus in the Crowe IV patients. The “windswept deformity” was observed in each of the groups; however, “long leg arthropathy” was only found in the Crowe IVa group. PMID:27733883

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

    SciTech Connect

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

    2013-06-15

    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. This 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.

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

    PubMed Central

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

    2013-01-01

    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. This 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. PMID:26229610

  9. Bulk Dislocation Core Dissociation Probed by Coherent X Rays in Silicon

    SciTech Connect

    Jacques, V. L. R.; Pinsolle, E.; Ravy, S.; Sauvage-Simkin, M.; Le Bolloc'h, D.; Livet, F.

    2011-02-11

    We report on a new approach to probe bulk dislocations by using coherent x-ray diffraction. Coherent x rays are particularly suited for bulk dislocation studies because lattice phase shifts in condensed matter induce typical diffraction patterns which strongly depend on the fine structure of the dislocation cores. The strength of the method is demonstrated by performing coherent diffraction of a single dislocation loop in silicon. A dissociation of a bulk dislocation is measured and proves to be unusually large compared to surface dislocation dissociations. This work opens a route for the study of dislocation cores in the bulk in a static or dynamical regime, and under various external constraints.

  10. Dislocation Structure and Mobility in hcp ^{4}He.

    PubMed

    Landinez Borda, Edgar Josué; Cai, Wei; de Koning, Maurice

    2016-07-22

    Using path-integral Monte Carlo simulations, we assess the core structure and mobility of the screw and edge basal-plane dislocations in hcp ^{4}He. 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 the partial dislocations is negligible, consistent with the recent experimental observations of giant plasticity. Further results indicate that both the structure of the partial cores and the zero-point fluctuations play a role in this extreme mobility.

  11. Plastic anisotropy and dislocation trajectory in BCC metals

    PubMed Central

    Dezerald, Lucile; Rodney, David; Clouet, Emmanuel; Ventelon, Lisa; Willaime, François

    2016-01-01

    Plasticity in body-centred cubic (BCC) metals at low temperatures is atypical, marked in particular by an anisotropic elastic limit in clear violation of the famous Schmid law applicable to most other metals. This effect is known to originate from the behaviour of the screw dislocations; however, the underlying physics has so far remained insufficiently understood to predict plastic anisotropy without adjustable parameters. Here we show that deviations from the Schmid law can be quantified from the deviations of the screw dislocation trajectory away from a straight path between equilibrium configurations, a consequence of the asymmetrical and metal-dependent potential energy landscape of the dislocation. We propose a modified parameter-free Schmid law, based on a projection of the applied stress on the curved trajectory, which compares well with experimental variations and first-principles calculations of the dislocation Peierls stress as a function of crystal orientation. PMID:27221965

  12. Plastic anisotropy and dislocation trajectory in BCC metals.

    PubMed

    Dezerald, Lucile; Rodney, David; Clouet, Emmanuel; Ventelon, Lisa; Willaime, François

    2016-05-25

    Plasticity in body-centred cubic (BCC) metals at low temperatures is atypical, marked in particular by an anisotropic elastic limit in clear violation of the famous Schmid law applicable to most other metals. This effect is known to originate from the behaviour of the screw dislocations; however, the underlying physics has so far remained insufficiently understood to predict plastic anisotropy without adjustable parameters. Here we show that deviations from the Schmid law can be quantified from the deviations of the screw dislocation trajectory away from a straight path between equilibrium configurations, a consequence of the asymmetrical and metal-dependent potential energy landscape of the dislocation. We propose a modified parameter-free Schmid law, based on a projection of the applied stress on the curved trajectory, which compares well with experimental variations and first-principles calculations of the dislocation Peierls stress as a function of crystal orientation.

  13. Localization of Oscillations on Dislocations in Piezoelectric Crystals

    NASA Astrophysics Data System (ADS)

    Gestrin, S. G.; Schukina, E. V.

    2014-05-01

    Longitudinal oscillations localized on dislocations are shown to exist in C4v piezoelectric crystals. Dispersion equations are constructed for axially symmetric and localized screw waves. Frequency regions separating their frequencies from the spectrum of volume oscillations are identified.

  14. Open Anterior Dislocation of the Hip in Togo

    PubMed Central

    Anani, Abalo; Yannick, Dellanh; Gamal, Ayouba; Assang, Dossim

    2016-01-01

    Anterior traumatic dislocations of the hip are much less common than posterior dislocations. To date, 14 cases of open anterior dislocation of the hip associated with such injuries, acetabular and femoral head fractures and femoral vascular and nerve damage have been reported. We present a case of a 23-year-old male who sustained open anterior dislocation of the hip with ipsilateral fracture of the greater trochanter after an accident on the public highway. Additional lesions included an iliac wing fracture and a perineal wound. We report this case because of the rarity and seriousness of this injury due to its progressive complications and difficulties related to its management, which are typical to a developing country like ours. PMID:27247749

  15. Posteromedial dislocation of the ankle without fracture or diastasis.

    PubMed

    Wang, L C; Love, M B

    1993-02-01

    This case report describes a patient with posteromedial dislocation of the ankle without fracture and without disruption of the tibiofibular syndesmosis. The pathogenesis of this uncommon lesion is discussed.

  16. Plastic anisotropy and dislocation trajectory in BCC metals

    NASA Astrophysics Data System (ADS)

    Dezerald, Lucile; Rodney, David; Clouet, Emmanuel; Ventelon, Lisa; Willaime, François

    2016-05-01

    Plasticity in body-centred cubic (BCC) metals at low temperatures is atypical, marked in particular by an anisotropic elastic limit in clear violation of the famous Schmid law applicable to most other metals. This effect is known to originate from the behaviour of the screw dislocations; however, the underlying physics has so far remained insufficiently understood to predict plastic anisotropy without adjustable parameters. Here we show that deviations from the Schmid law can be quantified from the deviations of the screw dislocation trajectory away from a straight path between equilibrium configurations, a consequence of the asymmetrical and metal-dependent potential energy landscape of the dislocation. We propose a modified parameter-free Schmid law, based on a projection of the applied stress on the curved trajectory, which compares well with experimental variations and first-principles calculations of the dislocation Peierls stress as a function of crystal orientation.

  17. Elastic field of approaching dislocation loop in isotropic bimaterial

    NASA Astrophysics Data System (ADS)

    Wu, Wenwang; Xia, Re; Xu, Shucai; Qian, Guian; Zhang, Jinhuan

    2015-10-01

    A semi-analytical solution is developed for calculating interface traction stress (ITS) fields due to elastic modulus mismatch across the interface plane of isotropic perfectly bounded bimaterial system. Based on the semi-analytical approaches developed, ITS is used to correct the bulk elastic field of dislocation loop within infinite homogenous medium, and to produce continuous displacement and stress fields across the perfectly-bounded interface. Firstly, calculation examples of dislocation loops in Al-Cu bimaterial system are performed to demonstrate the efficiency of the developed semi-analytical approach; Then, the elastic fields of dislocation loops in twinning Cu and Cu-Nb bimaterial are analyzed; Finally, the effect of modulus mismatch across interface plane on the elastic field of bimaterial system is investigated, it is found that modulus mismatch has a drastic impact on the elastic fields of dislocation loops within bimaterial system.

  18. Thermal Activation of Dislocations in Large Scale Obstacle Bypass

    SciTech Connect

    Martinez Saez, Enrique; Sobie, Cameron; Wen, Wei; Capolungo, Laurent; Patra, Anirban; McDowell, David L.; Tome, Carlos

    2016-08-18

    Irradiation-created defects diffuse and agglomerate presenting obstacles for the dislocation motion (both glide and climb). This effect leads to hardening and loss of toughness, which might drive the system to failure.

  19. Dislocation Structure and Mobility in hcp He4

    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

  20. Dislocation-induced superfluidity in a model supersolid

    NASA Astrophysics Data System (ADS)

    Dasbiswas, Kinjal; Goswami, Debajit; Yoo, Chi-Deuk; Dorsey, Alan

    2010-03-01

    The effect of an edge dislocation in inducing superfluidity is explored by coupling the elastic strain field of the dislocation to the superfluid density, and solving the corresponding Ginzburg-Landau theory. It is shown that superfluid density is induced along a single dislocation below a critical temperature determined by the ground state solution of a 2D Schr"odinger equation with a dipolar potential. This superfluid behavior can be described by a 1D Ginzburg-Landau equation obtained through a weakly nonlinear analysis. We then extend our analysis to a network of dislocation lines considered before by Shevchenko and Toner, which could serve as a model for superflow through solid ^4He. The effect of fluctuations and dynamics are included through a full time dependent Ginzburg-Landau theory.

  1. Thermally-Active Screw Dislocations in Si Nanowires and Nanotubes

    NASA Astrophysics Data System (ADS)

    Dumitrica, Traian; Xiong, Shiyun; Ma, Jihong; Volz, Sebastian

    2014-03-01

    New properties appear when nanomaterials contain dislocations. Understanding whether these features, which arise naturally during growth, are beneficial or problematic becomes essential for developing applications. Here we investigate 110 Si nanowire and nanotube structures containing an axial screw dislocation, as described by objective molecular dynamics coupled with the classical Tersoff potential. By means of direct nonequilibrium molecular dynamics simulations, we uncover significant reductions in thermal conductivity when nanostructures contain axial screw dislocations with closed and open cores. Analysis based on the atomistic Green function method reveals that in nanowires, the effect originates largely in the phonon-phonon scattering due to the enhanced anharmonicity introduced by highly distorted core region of the dislocation. In nanotubes, the inner surface compensates effectively for the missing core region. The uncovered effect can act in combination with other already known thermal conductivity limiting mechanisms, and thus can enable the further optimization of the figure of merit for a new family of complex thermoelectric nanomaterials.

  2. ParaDiS-FEM dislocation dynamics simulation code primer

    SciTech Connect

    Tang, M; Hommes, G; Aubry, S; Arsenlis, A

    2011-09-27

    The ParaDiS code is developed to study bulk systems with periodic boundary conditions. When we try to perform discrete dislocation dynamics simulations for finite systems such as thin films or cylinders, the ParaDiS code must be extended. First, dislocations need to be contained inside the finite simulation box; Second, dislocations inside the finite box experience image stresses due to the free surfaces. We have developed in-house FEM subroutines to couple with the ParaDiS code to deal with free surface related issues in the dislocation dynamics simulations. This primer explains how the coupled code was developed, the main changes from the ParaDiS code, and the functions of the new FEM subroutines.

  3. AC resistance measuring instrument

    DOEpatents

    Hof, P.J.

    1983-10-04

    An auto-ranging AC resistance measuring instrument for remote measurement of the resistance of an electrical device or circuit connected to the instrument includes a signal generator which generates an AC excitation signal for application to a load, including the device and the transmission line, a monitoring circuit which provides a digitally encoded signal representing the voltage across the load, and a microprocessor which operates under program control to provide an auto-ranging function by which range resistance is connected in circuit with the load to limit the load voltage to an acceptable range for the instrument, and an auto-compensating function by which compensating capacitance is connected in shunt with the range resistance to compensate for the effects of line capacitance. After the auto-ranging and auto-compensation functions are complete, the microprocessor calculates the resistance of the load from the selected range resistance, the excitation signal, and the load voltage signal, and displays of the measured resistance on a digital display of the instrument. 8 figs.

  4. AC Resistance measuring instrument

    DOEpatents

    Hof, Peter J.

    1983-01-01

    An auto-ranging AC resistance measuring instrument for remote measurement of the resistance of an electrical device or circuit connected to the instrument includes a signal generator which generates an AC excitation signal for application to a load, including the device and the transmission line, a monitoring circuit which provides a digitally encoded signal representing the voltage across the load, and a microprocessor which operates under program control to provide an auto-ranging function by which range resistance is connected in circuit with the load to limit the load voltage to an acceptable range for the instrument, and an auto-compensating function by which compensating capacitance is connected in shunt with the range resistance to compensate for the effects of line capacitance. After the auto-ranging and auto-compensation functions are complete, the microprocessor calculates the resistance of the load from the selected range resistance, the excitation signal, and the load voltage signal, and displays of the measured resistance on a digital display of the instrument.

  5. AC Optimal Power Flow

    SciTech Connect

    2016-10-04

    In this work, we have implemented and developed the simulation software to implement the mathematical model of an AC Optimal Power Flow (OPF) problem. The objective function is to minimize the total cost of generation subject to constraints of node power balance (both real and reactive) and line power flow limits (MW, MVAr, and MVA). We have currently implemented the polar coordinate version of the problem. In the present work, we have used the optimization solver, Knitro (proprietary and not included in this software) to solve the problem and we have kept option for both the native numerical derivative evaluation (working satisfactorily now) as well as for analytical formulas corresponding to the derivatives being provided to Knitro (currently, in the debugging stage). Since the AC OPF is a highly non-convex optimization problem, we have also kept the option for a multistart solution. All of these can be decided by the user during run-time in an interactive manner. The software has been developed in C++ programming language, running with GCC compiler on a Linux machine. We have tested for satisfactory results against Matpower for the IEEE 14 bus system.

  6. Dislocation interactions with characteristic interfaces in AgCu eutectic

    NASA Astrophysics Data System (ADS)

    Eftink, Benjamin P.

    In the AgCu eutectic alloy, the observation of deformation twinning in Cu proposed to be induced by direct transmission of deformation twinning partial dislocations in Ag highlights the question of how interfaces in bi-phase materials respond to deformation. AgCu eutectic alloy was produced by both directional solidification and cast water-quenching. Control over processing variables enabled the synthesis of Ag/Cu eutectic with three predominant interface types: ones with a cube-on-cube orientation relationship with {111} Ag||{111}Cu interface habit planes, twin orientation relationship with {111}Ag||{111}Cu interface habit planes, and twin orientation relationship with near {313}Ag||{ 112}Cu interface habit planes. How dislocations interacted with each of the interfaces was determined using in situ and ex situ TEM straining experiments. It was determined that how strain transfers across Ag/Cu interfaces is consistent with criteria of strain transfer across grain boundaries in single phase materials. Specifically, the magnitude of the Burgers vector of the residual dislocation, |bres |, left in the interface should be small. This criterion was determining enough to drive Cu to twin under conditions where otherwise it would not. When transmission of a dislocation would result in a high |bres|, which is common for most slip systems encountering an incoherent twin interface, the interfaces were observed to block the dislocations. It was found that the increased effectiveness of the incoherent twin interfaces to block dislocations compared to the cube-on-cube interfaces resulted in an increased in the yield strength of the material. Interfaces with the cube-on-cube orientation relationship and mutual {111} interface plane between Ag and Cu results in transfer of twinning defects from Ag into Cu. This was found at length scales in the tens of nano-meters to the micron range. Twinning in both phases was observed after both split-Hopkinson pressure bar ex situ straining

  7. Dislocation Damping and Anisotropic Attenuation in the Earth's Upper Mantle

    NASA Astrophysics Data System (ADS)

    Jackson, I.; Farla, R. J.; Fitz Gerald, J. D.; Faul, U.; Zimmerman, M. E.

    2011-12-01

    Seismic anisotropy, attributed to olivine lattice preferred orientation, suggests that tectonic deformation in the Earth's shallow upper mantle involves dislocation creep. Reversible glide of dislocations, generated by the prevailing/fossil tectonic stress, may result in anelastic relaxation that contributes to the reduction of seismic wave speeds and associated attenuation. To test this hypothesis, polycrystalline olivine specimens were synthesised from synthetic (sol-gel) precursors and hot-pressed at high temperature. The hot-pressed material is fully dense, fine-grained and essentially dry and melt-free olivine. Other, coarser-grained material was synthesised from San Carlos olivine powders. These contrasting materials provided the opportunity to distinguish between the influences of grain size and dislocation density. Selected specimens were deformed by dislocation creep either in compression or torsion and characterised for dislocation density via oxidation and backscattered electron imaging. Additionally, the dislocation recovery rate was determined for both olivines at different temperatures and time durations. The results established that a maximum temperature of 1100C should allow a relatively stable dislocation density to be maintained during prolonged mechanical testing (> 50 hours). The shear modulus and associated strain-energy dissipation in both hot-pressed and pre-deformed specimens were subsequently measured at seismic frequencies under conditions of simultaneous high pressure and temperature with torsional forced-oscillation methods. These experiments were carried out with strain amplitudes < 10-5 to permit direct comparison with seismological models. The high-temperature dissipation background, attributed in undeformed fine-grained materials to grain-boundary sliding, and the associated partial relaxation of the shear modulus, are systematically enhanced in the pre-deformed materials - suggesting a role for the dislocations introduced during the

  8. Elastic model of a dislocation center for martensite nucleation

    SciTech Connect

    Vereshchagin, V.P.; Kashchenko, M.P.

    1995-01-01

    The possibility of spontaneous nucleation of a crystal of new phase when the original structure is metastable is usually connected with the catalyzing effect of defects playing the role of nucleation centers. In the case of the {gamma}{r_arrow}{alpha} martensite transformation in iron alloys, even individual dislocations can act as such defects, based on analysis of long-range elastic fields of isolated linear dislocations in a linearly elastic anisotropic continuum, the authors established the existence of a correlation between the geometric characteristics of the elastically deformed state in the vicinity of 60-degree and 30-degree dislocations and the structure and morphological characteristics of {alpha}-martensite observed in massive iron alloy samples. These results suggest that the dislocation affects the pathway of the martensite reaction and allows the authors to say that the specific characteristics of heterogeneous nucleation of new phase for the martensite mechanism of the {gamma}{r_arrow}{alpha} transformation involves singling out a single structural rearrangement variant which is suitable from the standpoint of adapation of the transforming lattice to the characteristic features of the elastically deformed state created by the dislocation. The possibilities for such adaption are limited by the crystallography of the transformation and the reactions of the surrounding austenite occurring when regular connections exist with the morphological characteristics of the martensite crystal, and are not necessarily compatible with the individual features of the elastic field of each dislocation. Considering this, the authors can introduce the concept of a dislocation center for nucleation of a martensite crystal about the region of the dislocation where conditions are realized which are favorable for the formation of a nucleus of martensite crystal of a certain shape and orientation, and they can develop an elastic model corresponding to this concept.

  9. Pediatric open elbow dislocation without fracture: A case report

    PubMed Central

    Polat, Gökhan; Karademir, Gökhan; Akgül, Turgut; Ceylan, Hasan Hüseyin

    2014-01-01

    INTRODUCTION Elbow dislocations in children are rare injuries. These injuries are often in the form of complex injuries that is accompanied by the median nerve damage and medial epicondyle fracture in the pediatric age group. Open elbow dislocation without fracture in the pediatric age group has been reported very rarely in the literature. PRESENTATION OF CASE The purpose of this study is to present an 8-year-old patient who has open elbow dislocation without fracture accompanying with brachial artery injury. In the clinical examination of the patient, there was an open wound in the transverse antecubital region. After repair of brachial artery injury, open reduction was performed under general anesthesia. In the postoperative clinical examination at 6 months, left elbow flexion was 140°, extension was full and there were no deficit in the supination and pronation of the forearm. DISCUSSION Elbow dislocation without fracture in pediatric patients is a very rare injury. Usually the trauma mechanism of elbow dislocation is falling on outstretched hand with elbow in approximately 30° of flexion. However our patient had fallen on outstretched hand with elbow in full extension. Although this type of trauma mechanism is typical for supracondylar humerus fractures in pediatric age group, in our patient an open posterior elbow dislocation without fracture had occurred. CONCLUSION Pediatric elbow dislocations are rare injuries and the management of these injuries can be technically demanding due to concurrent neurovascular injuries. An open dislocation without fracture is very rare and it should be treated with immediate intervention, an effective teamwork and good rehabilitation. PMID:25460475

  10. Double level arterial injury with neuropraxia following anterior shoulder dislocation

    PubMed Central

    Zaraa, Mourad; Sehli, Heithem; Mahjoub, Sabri; Dridi, Moez; Mbarek, Mondher

    2015-01-01

    Vascular and nervous complications are rare after shoulder dislocation. We report the case of a double level arterial injury with neuropraxia following anterior shoulder dislocation that was diagnosed by MultiDetector-row Computed Tomographic (MDCT) angiography and treated by surgical bypass graft and embolectomy. Our case is original, not only because of the rarity of these complications, but also because of the thromboembolism of brachial artery which could be undiagnosed and could compromise prognosis. PMID:26566344

  11. [Congenital dislocation of the knee: report of 2 cases].

    PubMed

    Ochoa Gómez, L; Sánchez Gimeno, J; García Barrecheguren, E; Marulanda Del Valle, K; Almonte Adón, K; Guerrero Laleona, C

    2015-01-01

    Congenital dislocation of the knee is a rare disease. The diagnosis is made at birth by clinical findings, and confirmed radiologically. It has been associated with various etiologies from intrauterine fetal malpositions to genetic disorders. The prognosis depends on early treatment and whether there are other congenital anomalies. We report two new cases of congenital dislocation of the knee, observed in our hospital during the period of a month, diagnosed immediately after birth, and both with a good clinical outcome.

  12. Identification of /sup 233/Ac

    SciTech Connect

    Chu, Y.Y.; Zhou, M.L.

    1983-09-01

    We report in this paper identification of the new isotope /sup 233/Ac. Uranium targets were irradiated with 28 GeV protons; after rapid retrieval of the target and separation of actinium from thorium, /sup 233/Ac was allowed to decay into the known /sup 233/Th daughter. Exhaustive chemical purification was employed to permit the identification of /sup 233/Th via its characteristic ..gamma.. radiations. The half-life derived for /sup 233/Ac from several experiments is 2.3 +- 0.3 min. The production cross section for /sup 233/Ac is 100 ..mu..b.

  13. Reactivity of pyrites and dislocation density

    SciTech Connect

    Pollack, S.S.; Martello, D.V.; Diehl, J.R.; Tamilia, J.V. ); Graham, R.A. )

    1991-01-01

    Highly reactive coal pyrites and unstable museum specimens are easily distinguished from the stable pyrites by the growth of white crystals that cover samples exposed to room atmosphere for short periods of time. Continued exposure to the atmosphere will eventually cause the specimens to fall apart. The term rotten pyrite has been applied to museum specimens that fall apart in this way. SEM studies show that reactive (rotten) pyrites contain between 100 and 10,000 times more dislocations than stable pyrites. Shock-loading of a stable pyrite to 7.5 GPa and 17 GPa increased its reactivity by a factor of two, probably caused by an increase in the number of imperfections. However, shock-loading at 22 GPa decreased the reactivity of pyrite because the imperfections produced at the higher pressure were removed during annealing the sample received at the higher temperature. Although there was a factor of six difference between the most and least reactive shocked MCB (commercial pyrite) samples, shock-loading did not increase the reactivity of the MCB pyrite to that of the Queensland coal pyrite. The results in hand show that while shock-loading produces sufficient imperfections to increase the reactivity of pyrites, there is insufficient data to show that imperfections are the main reason why some coal pyrites are highly reactive. 9 refs., 1 fig., 1 tab.

  14. Dislocation theory of melting for iron, revisited

    SciTech Connect

    Poirier, J.P.; Shankland, T.J.

    1993-11-01

    Melting point T{sub m} of iron at conditions of the Earth`s inner core boundary (ICB) has been calculated from dislocation theory of melting in metals. Monte Carlo calculations were used to estimate uncertainties introduced by uncertainty in the geophysical parameters that are used in the calculations. These calculations take into account the effects of pressure at ICB conditions and of possible freezing point depression resulting from dilution of pure iron in the outer core. With this approach T{sub m} of pure {var_epsilon}-Fe at a pressure of 330 GPa and without freezing point depression is 6160 {plus_minus} 250 K; for a 1000 K freezing point depression it is 6110 K. T{sub m} of pure {gamma}-Fe is 6060 K, a value that is not significantly different. A possible {alpha}{prime} phase would melt at 5600 K. These values agree with calculated shock wave determinations of T{sub m}. Although calculated T{sub m} of the pure phase is little affected by assumptions about the extent of freezing point depression, the estimated temperature of the inner core boundary is lower by the breezing point depression, perhaps 500--1000 K less than T{sub m} of a pure phase.

  15. Dislocation theory of melting for iron, revisited

    SciTech Connect

    Poirier, J. ); Shankland, T.J. )

    1994-07-10

    The melting point T[sub m] of iron at conditions of the Earth's inner core boundary (ICB) has been calculated from the dislocation theory of melting in metals. Monte Carlo calculations were used to estimate uncertainties introduced by uncertainty in the geophysical parameters that are used in the calculations. These calculations take into account the effects of pressure at ICB conditions and of possible freezing point depression resulting from dilution of pure iron in the outer core. With this approach T[sub m] of pure [epsilon]-Fe at a pressure of 330 GPa and without freezing point depression is 6160[plus minus]250 K; for a 1000 K freezing point depression it is 6110 K. T[sub m] of pure [gamma]-Fe is 6060 K, a value that is not significantly different. A possible [alpha][prime] phase would melt at 5600 K. These values agree with calculated shock wave determinations of T[sub m]. Although calculated T[sub m] of the pure phase is little affected by assumptions about the extent of freezing point depression, the estimated temperature of the inner core boundary is lower by the freezing point depression, perhaps 500--1000 K less than T[sub m] of a pure phase. [copyright] 1994 American Institute of Physics

  16. Hypermobile joints

    MedlinePlus

    ... A.M. Editorial team. Related MedlinePlus Health Topics Joint Disorders Browse the Encyclopedia A.D.A.M., Inc. is accredited by URAC, also known as the American Accreditation HealthCare Commission (www.urac.org). URAC's accreditation program is an ...

  17. Bilateral posterior shoulder dislocation after electrical shock: A case report

    PubMed Central

    Ketenci, Ismail Emre; Duymus, Tahir Mutlu; Ulusoy, Ayhan; Yanik, Hakan Serhat; Mutlu, Serhat; Durakbasa, Mehmet Oguz

    2015-01-01

    Introduction Posterior dislocation of the shoulder is a rare and commonly missed injury. Unilateral dislocations occur mostly due to trauma. Bilateral posterior shoulder dislocations are even more rare and result mainly from epileptic seizures. Electrical injury is a rare cause of posterior shoulder dislocation. Injury mechanism in electrical injury is similar to epileptic seizures, where the shoulder is forced to internal rotation, flexion and adduction. Presentation of case This report presents a case of bilateral posterior shoulder dislocation after electrical shock. We were able to find a few individual case reports describing this condition. The case was acute and humeral head impression defects were minor. Our treatment in this case consisted of closed reduction under general anesthesia and applying of orthoses which kept the shoulders in abduction and external rotation. A rehabilitation program was begun after 3 weeks of immobilization. After 6 months of injury the patient has returned to work. 20 months postoperatively, at final follow-up, he was painless and capable of performing all of his daily activities. Discussion The amount of bilateral shoulder dislocations after electrical injury is not reported but is known to be very rare. The aim of this case presentation is to report an example for this rare entity, highlight the difficulties in diagnosis and review the treatment options. Conclusion Physical examination and radiographic evaluation are important for quick and accurate diagnosis. PMID:26904192

  18. 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.

  19. Surface-controlled dislocation multiplication in metal micropillars.

    PubMed

    Weinberger, Christopher R; Cai, Wei

    2008-09-23

    Understanding the plasticity and strength of crystalline materials in terms of the dynamics of microscopic defects has been a goal of materials research in the last 70 years. The size-dependent yield stress observed in recent experiments of submicrometer metallic pillars provides a unique opportunity to test our theoretical models, allowing the predictions from defect dynamics simulations to be directly compared with mechanical strength measurements. Although depletion of dislocations from submicrometer face-centered-cubic (FCC) pillars provides a plausible explanation of the observed size-effect, we predict multiplication of dislocations in body-centered-cubic (BCC) pillars through a series of molecular dynamics and dislocation dynamics simulations. Under the combined effects from the image stress and dislocation core structure, a dislocation nucleated from the surface of a BCC pillar generates one or more dislocations moving in the opposite direction before it exits from the surface. The process is repeatable so that a single nucleation event is able to produce a much larger amount of plastic deformation than that in FCC pillars. This self-multiplication mechanism suggests a need for a different explanation of the size dependence of yield stress in FCC and BCC pillars.

  20. Atomistically-informed Dislocation Dynamics in fcc Crystals

    SciTech Connect

    Martinez, E; Marian, J; Arsenlis, T; Victoria, M; Perlado, J M

    2006-09-06

    We develop a nodal dislocation dynamics (DD) model to simulate plastic processes in fcc crystals. The model explicitly accounts for all slip systems and Burgers vectors observed in fcc systems, including stacking faults and partial dislocations. We derive simple conservation rules that describe all partial dislocation interactions rigorously and allow us to model and quantify cross-slip processes, the structure and strength of dislocation junctions and the formation of fcc-specific structures such as stacking fault tetrahedra. The DD framework is built upon isotropic non-singular linear elasticity, and supports itself on information transmitted from the atomistic scale. In this fashion, connection between the meso and micro scales is attained self-consistently with core parameters fitted to atomistic data. We perform a series of targeted simulations to demonstrate the capabilities of the model, including dislocation reactions and dissociations and dislocation junction strength. Additionally we map the four-dimensional stress space relevant for cross-slip and relate our findings to the plastic behavior of monocrystalline fcc metals.

  1. Dislocation Starvation and Exhaustion Hardening in Mo-alloy Nanofibers

    SciTech Connect

    Chisholm, Claire; Bei, Hongbin; Lowry, M. B.; Oh, Jason; Asif, S.A. Syed; Warren, O.; Shan, Zhiwei; George, Easo P; Minor, Andrew

    2012-01-01

    The evolution of defects in Mo alloy nanofibers with initial dislocation densities ranging from 0 to 1.6 1014 m2 were studied using an in situ push-to-pull device in conjunction with a nanoindenter in a transmission electron microscope. Digital image correlation was used to determine stress and strain in local areas of deformation. When they had no initial dislocations the Mo alloy nanofibers suffered sudden catastrophic elongation following elastic deformation to ultrahigh stresses. At the other extreme fibers with a high dislocation density underwent sustained homogeneous deformation after yielding at much lower stresses. Between these two extremes nanofibers with intermediate dislocation densities demonstrated a clear exhaustion hardening behavior, where the progressive exhaustion of dislocations and dislocation sources increases the stress required to drive plasticity. This is consistent with the idea that mechanical size effects ( smaller is stronger ) are due to the fact that nanostructures usually have fewer defects that can operate at lower stresses. By monitoring the evolution of stress locally we find that exhaustion hardening causes the stress in the nanofibers to surpass the critical stress predicted for self-multiplication, supporting a plasticity mechanism that has been hypothesized to account for the rapid strain softening observed in nanoscale bcc materials at high stresses.

  2. Direct observation of individual dislocation interaction processes with grain boundaries

    PubMed Central

    Kondo, Shun; Mitsuma, Tasuku; Shibata, Naoya; Ikuhara, Yuichi

    2016-01-01

    In deformation processes, the presence of grain boundaries has a crucial influence on dislocation behavior; these boundaries drastically change the mechanical properties of polycrystalline materials. It has been considered that grain boundaries act as effective barriers for dislocation glide, but the origin of this barrier-like behavior has been a matter of conjecture for many years. We directly observe how the motion of individual dislocations is impeded at well-defined high-angle and low-angle grain boundaries in SrTiO3, via in situ nanoindentation experiments inside a transmission electron microscope. Our in situ observations show that both the high-angle and low-angle grain boundaries impede dislocation glide across them and that the impediment of dislocation glide does not simply originate from the geometric effects; it arises as a result of the local structural stabilization effects at grain boundary cores as well, especially for low-angle grain boundaries. The present findings indicate that simultaneous consideration of both the geometric effects and the stabilization effects is necessary to quantitatively understand the dislocation impediment processes at grain boundaries. PMID:27847862

  3. In Situ TEM Observation of Dislocation Evolutionin Polycrystalline UO2

    SciTech Connect

    L. F. HE; 1 M. A. KIRK; Argonne National Laboratory; J. Gan; T. R. ALLEN

    2014-10-01

    In situ transmission electron microscopy observation of polycrystalline UO2 (with average grain size of about 5 lm) irradiated with Kr ions at 600C and 800C was conducted to understand the radiation-induced dislocation evolution under the influence of grain boundaries. The dislocation evolution in the grain interior of polycrystalline UO2 was similar under Kr irradiation at different ion energies and temperatures. As expected, it was characterized by the nucleation and growth of dislocation loops at low irradiation doses, followed by transformation to extended dislocation lines and tangles at high doses. For the first time, a dislocation-denuded zone was observed near a grain boundary in the 1-MeV Kr-irradiated UO2 sample at 800C. The denuded zone in the vicinity of grain boundary was not found when the irradiation temperature was at 600C. The suppression of dislocation loop formation near the boundary is likely due to the enhanced interstitial diffusion toward grain boundary at the high temperature.

  4. Identification of dislocation etch pits in n-type GaAs by NIR transmission microscopy

    NASA Technical Reports Server (NTRS)

    Cao, X. Z.; Witt, A. F.

    1991-01-01

    An optical method is described for identifying dislocation etch pits in n-type GaAS, using near-IR brightfield transmission microscopy. Dislocations are revealed in a nondestructive manner through contrasts that are likely due to impurity decoration of the dislocation lines. By subjecting the same wafers to a photoetching technique, it was established that each etch pit on the surface is associated with a dislocation and that the termination of each (decorated) dislocation is an etch pit.

  5. A single theory for some quasi-static, supersonic, atomic, and tectonic scale applications of dislocations

    NASA Astrophysics Data System (ADS)

    Zhang, Xiaohan; Acharya, Amit; Walkington, Noel J.; Bielak, Jacobo

    2015-11-01

    We describe a model based on continuum mechanics that reduces the study of a significant class of problems of discrete dislocation dynamics to questions of the modern theory of continuum plasticity. As applications, we explore the questions of the existence of a Peierls stress in a continuum theory, dislocation annihilation, dislocation dissociation, finite-speed-of-propagation effects of elastic waves vis-a-vis dynamic dislocation fields, supersonic dislocation motion, and short-slip duration in rupture dynamics.

  6. Delayed Avascular Necrosis and Fragmentation of the Lunate Following Perilunate Dislocation.

    PubMed

    Wilke, Benjamin; Kakar, Sanjeev

    2015-06-01

    Perilunate and perilunate fracture dislocations are high-energy injuries with the wrist loaded in extension, ulnar deviation, and intercarpal supination. The force vector travels from a radial to a ulnar direction and can result in complex carpal instability. The diagnosis is often delayed, which can result in suboptimal outcomes. Nonoperative management can produce inferior results, with patients experiencing pain and weakness. Therefore, early treatment with open reduction and internal fixation is recommended to assess the osteochondral and ligamentous disruption and to achieve anatomic reduction of the carpus. Despite this, these patients can develop radiographic degenerative joint disease, which can be seen in up to 90% of cases. This can be due to difficulty in holding and maintaining carpal reduction. Increased radiodensity of the lunate following these injuries has been observed but is believed to be a transient phenomenon without risk of progression to avascular necrosis. This may be due to the blood supply of the lunate, which has varied patterns of intraosseous and extraosseous vascularity. The authors report a patient who developed avascular necrosis and delayed lunate fragmentation following a May-field Type IV perilunate dislocation. This finding highlights the importance of long-term follow-up with these patients.

  7. Type IIA Monteggia Fracture Dislocation with Ipsilateral Distal Radius Fracture in Adult – A Rare Association

    PubMed Central

    James, Boblee

    2016-01-01

    Monteggia fracture constitutes about 5-10% of the forearm fractures. Monteggia fracture by definition is proximal ulnar fracture with disruption of proximal radioulnar joint. Bado classified Monteggia fracture dislocation into four types and Jupiter subclassified type II Bado’s fractures into four types. The associated injury in the form of distal radial fractures and distal humerus fractures are rare though many cases of distal radial physeal injuries have been reported in paediatric population. Hereby we report a rare association of type IIA Monteggia fracture dislocation with ipsilateral distal radius fracture in an adult patient. This case report also highlights on proper examination and full length radiographs of forearm to avoid missing injury at wrist in cases of elbow injuries. Management of such complex injuries included open reduction and internal fixation of olecronon fracture, distal radius fracture and radial head resection. Functional outcome at six months was good at wrist whereas at elbow, stiffness was a major concern with elbow range of movement from 40°-110°. PMID:27656518

  8. Statistical description of the motion of dislocation kinks in a random field of impurities adsorbed by a dislocation

    SciTech Connect

    Petukhov, B. V.

    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 delay 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.

  9. Statistical approach to dislocation dynamics: From dislocation correlations to a multiple-slip continuum theory of plasticity

    NASA Astrophysics Data System (ADS)

    Limkumnerd, Surachate; van der Giessen, Erik

    2008-05-01

    Due to recent successes of a statistical-based nonlocal continuum crystal plasticity theory for single-glide in explaining various aspects such as dislocation patterning and size-dependent plasticity, several attempts have been made to extend the theory to describe crystals with multiple-slip systems using ad hoc assumptions. We present here a mesoscale continuum theory of plasticity for multiple-slip systems of parallel edge dislocations. We begin by constructing the Bogolyubov Born Green Yvon Kirkwood integral equations relating different orders of dislocation correlation functions in a grand canonical ensemble. Approximate pair correlation functions are obtained for single-slip systems with two types of dislocations and, subsequently, for general multiple-slip systems of both charges. The effect of the correlations manifests itself in the form of an entropic force in addition to the external stress and the self-consistent internal stress. Comparisons with a previous multiple-slip theory based on phenomenological considerations shall be discussed.

  10. Elbow joint stability in relation to forced external rotation: An experimental study of the osseous constraint.

    PubMed

    Deutch, Søren R; Jensen, Steen L; Olsen, Bo S; Sneppen, Otto

    2003-01-01

    The objective of this study was to evaluate the osseous constraint related to forced forearm external rotation as the initial stage in a posterior elbow dislocation. Six joint specimens without soft tissues were examined in a joint analysis system developed for simulation of dislocation. The osseous stability, expressed as the maximal torque needed for pathologic external forearm rotation, increased from varus to valgus stress (P =.0001) and from 10 degrees to 90 degrees of elbow flexion (P =.012) and also tended to increase from forearm supination to pronation. The work of pathologic external forearm rotation until the point of maximal torque decreased from a maximum in full extension to a minimum at 30 degrees of elbow flexion (P =.03). The elbow in a slightly flexed position, varus stress, and forearm external rotation trauma might be the important biomechanical factors in the posterior elbow dislocation, and they might serve as guidelines during clinical investigation for posterolateral instability.

  11. Arthroscopic treatment of pigmented villonodular synovitis of the proximal tibiofibular joint.

    PubMed

    Lui, Tun Hing

    2015-08-01

    Disorders of the proximal tibiofibular joint should be kept in mind in the evaluation of lateral knee pain. They include osteoarthrosis, rheumatic disease, traumatic subluxation or dislocation, ganglion or synovial cysts, synostosis, synovial chondromatosis, pigmented villonodular synovitis and hypomobility of the joint. Peroneal nerve can be at risk with pathologies of the joint either by compressive effect or formation of intra-neural ganglion. A case of pigmented villonodular synovitis of the proximal tibiofibular joint was reported which presented with lateral knee pain. It was successfully treated by arthroscopic synovectomy. Level of evidence V.

  12. Digital ac monitor

    DOEpatents

    Hart, George W.; Kern, Jr., Edward C.

    1987-06-09

    An apparatus and method is provided for monitoring a plurality of analog ac circuits by sampling the voltage and current waveform in each circuit at predetermined intervals, converting the analog current and voltage samples to digital format, storing the digitized current and voltage samples and using the stored digitized current and voltage samples to calculate a variety of electrical parameters; some of which are derived from the stored samples. The non-derived quantities are repeatedly calculated and stored over many separate cycles then averaged. The derived quantities are then calculated at the end of an averaging period. This produces a more accurate reading, especially when averaging over a period in which the power varies over a wide dynamic range. Frequency is measured by timing three cycles of the voltage waveform using the upward zero crossover point as a starting point for a digital timer.

  13. Digital ac monitor

    DOEpatents

    Hart, G.W.; Kern, E.C. Jr.

    1987-06-09

    An apparatus and method is provided for monitoring a plurality of analog ac circuits by sampling the voltage and current waveform in each circuit at predetermined intervals, converting the analog current and voltage samples to digital format, storing the digitized current and voltage samples and using the stored digitized current and voltage samples to calculate a variety of electrical parameters; some of which are derived from the stored samples. The non-derived quantities are repeatedly calculated and stored over many separate cycles then averaged. The derived quantities are then calculated at the end of an averaging period. This produces a more accurate reading, especially when averaging over a period in which the power varies over a wide dynamic range. Frequency is measured by timing three cycles of the voltage waveform using the upward zero crossover point as a starting point for a digital timer. 24 figs.

  14. Cooling Floor AC Systems

    NASA Astrophysics Data System (ADS)

    Jun, Lu; Hao, Ding; Hong, Zhang; Ce, Gao Dian

    The present HVAC equipments for the residential buildings in the Hot-summer-and-Cold-winter climate region are still at a high energy consuming level. So that the high efficiency HVAC system is an urgently need for achieving the preset government energy saving goal. With its advantage of highly sanitary, highly comfortable and uniform of temperature field, the hot-water resource floor radiation heating system has been widely accepted. This paper has put forward a new way in air-conditioning, which combines the fresh-air supply unit and such floor radiation system for the dehumidification and cooling in summer or heating in winter. By analyze its advantages and limitations, we found that this so called Cooling/ Heating Floor AC System can improve the IAQ of residential building while keep high efficiency quality. We also recommend a methodology for the HVAC system designing, which will ensure the reduction of energy cost of users.

  15. A rare Lisfranc-type injury involving dorsal dislocation of the intermediate cuneiform

    PubMed Central

    Kalraiya, Ashish Jain; Vanhegan, Ivor; Cheung, Alan; Rudge, Ben

    2014-01-01

    Lisfranc injuries occur at the tarsometatarsal joint resulting from direct or indirect force to the midfoot. They account for only 0.2% of all fractures, with diagnoses easily missed on presentation. The resultant instability is often associated with significant morbidity to the patient. This report describes a Lisfranc injury sustained by a healthy gentleman who suffered indirect trauma to the foot when he fell from a standing height. Plain film radiographs and CT revealed dorsal dislocation of the intermediate cuneiform associated with fractures at the base of the third and fourth metatarsals. He underwent open reduction and internal fixation the following day. His Foot and Ankle Disability Index (FADI) score improved from 16.3 1 week postoperatively to 58.7 6 months postoperatively. This report describes a rare injury pattern resulting from indirect, low-energy trauma. We provide a guide to appropriate radiological imaging and evaluation in the assessment of these complex injuries. PMID:25073524

  16. Dual-mobility cups for revision due to instability are associated with a low rate of re-revisions due to dislocation

    PubMed Central

    2012-01-01

    Background and purpose Revision total hip arthroplasty (THA) due to recurrent dislocations is associated with a high risk of persistent instability. We hypothesized that the use of dual-mobility cups would reduce the risk of re-revision due to dislocation after revision THA. Patients and methods 228 THA cup revisions (in 228 patients) performed due to recurrent dislocations and employing a specific dual-mobility cup (Avantage) were identified in the Swedish Hip Arthroplasty Register. Kaplan-Meier survival analysis was performed with re-revision due to dislocation as the primary endpoint and re-revision for any reason as the secondary endpoint. Cox regression models were fitted in order to calculate the influence of various covariates on the risk of re-revision. Results 58 patients (25%) had been revised at least once prior to the index cup revision. The surgical approach at the index cup revision was lateral in 99 cases (44%) and posterior in 124 cases (56%). Median follow-up was 2 (0–6) years after the index cup revision, and by then 18 patients (8%) had been re-revised for any reason. Of these, 4 patients (2%) had been re-revised due to dislocation. Survival after 2 years with the endpoint revision of any component due to dislocation was 99% (95% CI: 97–100), and it was 93% (CI: 90–97) with the endpoint revision of any component for any reason. Risk factors for subsequent re-revision for any reason were age between 50–59 years at the time of the index cup revision (risk ratio (RR) = 5 when compared with age > 75, CI: 1–23) and previous revision surgery to the relevant joint (RR = 1.7 per previous revision, CI: 1–3). Interpretation The risk of re-revision due to dislocation after insertion of dual-mobility cups during revision THA performed for recurrent dislocations appears to be low in the short term. Since most dislocations occur early after revision THA, we believe that this device adequately addresses the problem of recurrent instability. Younger

  17. Characterization of dislocation structures in silicon carbide single crystals

    NASA Astrophysics Data System (ADS)

    Vetter, William M.

    1999-07-01

    Two types of defects in PVT-grown 6H and 4H-SiC crystals were studied: screw dislocations that follow the axial direction of the crystal and dislocations that follow directions in the crystal's basal plane. The screw dislocations possessed a range of Burgers vector magnitudes, multiples of the axial parameter c, that could be determined by x-ray topographic image analysis. Hollow cores termed "micropipes" were observed when Burgers, vectors were larger than 3c. The micropipes were studied by a variety of methods: optical microscopy, laser scanning confocal microscopy, scanning electron microscopy, transmission electron microscopy and atomic force microscopy. The micropipes were tubes 0.1 to 10mum in diameter. They were faceted, primarily along the {101¯0} planes, but also had {112¯0} facets. When encountering the growth surface of a crystal, they flared out into a trumpet-shape. Growth spirals sometimes occurred, originating from the trumpets' rims. The screw dislocations are visible in back-reflection synchrotron white beam x-ray topographs of basal-cut SiC wafers in striking contrast as black rings surrounding white circles, though such topographs are contaminated by a series of harmonic reflections, g = (0006n), where n = 3 to 16. By calculating and considering their intensities, and comparison with a g = 00018 Lang topograph taken with CuKalpha1 radiation, the g = 00024 harmonic was shown to be the most important contributor. Basal plane dislocations were seen in x-ray topographs of SiC looping from the points where screw dislocations occurred. Their extinction behavior showed they belonged to the set b = 13 <112¯0>. In some transmission electron micrographs, perfect dislocations with similar extinction behavior, along with partial dislocations with b = 13 <101¯0>, were seen originating from the micropipes' walls, curving out into the crystal a distance of 1 to 3mum, then back to terminate at the micropipe. Others led out of the field of view. Contrast is

  18. Automated ac galvanomagnetic measurement system

    NASA Technical Reports Server (NTRS)

    Szofran, F. R.; Espy, P. N.

    1985-01-01

    An automated, ac galvanomagnetic measurement system is described. Hall or van der Pauw measurements in the temperature range 10-300 K can be made at a preselected magnetic field without operator attendance. Procedures to validate sample installation and correct operation of other system functions, such as magnetic field and thermometry, are included. Advantages of ac measurements are discussed.

  19. Isolated volar surgical approach for the treatment of perilunate and lunate dislocations

    PubMed Central

    Başar, Hakan; Başar, Betül; Erol, Bülent; Tetik, Cihangir

    2014-01-01

    Background: Volar and/or dorsal surgical approaches are used for surgical treatment of perilunate and lunate dislocations. There are no accepted approaches for treatment in the literature. We evaluated the functional results of isolated volar surgical approach for the treatment of perilunate and lunate dislocation injuries. Materials and Methods: 9 patients (6 male and 3 female patients average age 34.5 ± 3.6 years) diagnosed with perilunate or lunate dislocations between January 2000 and January 2009 were involved in the study. The reduction was performed through isolated volar surgical approach and K-wire fixation, fracture stabilization with volar ligament repair was performed. Range of wrist joint motion, fracture healing, carpal stability, grip strength, return to work were evaluated and also direct radiographs were taken routinely at each control. The scapholunate interval and the scapholunate angle were evaluated radiographically. Evaluations of the clinical results were done using the DASH, VAS and Modified Mayo Wrist Scores. Results: The physical rehabilitation was started at 6th week, after the K-wires were removed. The average followup was 18.2 months (range 12-28 months). At the final followup, the average flexion extension arc was 105.0 ± 9.6° (74.6% of the other side), the average rotation arc was 138.8 ± 7.8° (81.5% of the other side) and the average radioulnar arc was 56.1 ± 9.9° (86.4% of the other side). The grip strength was 0.55 bar; 83.2% that the uninjured arm. According to the Mayo Modified Wrist score, the functional result was excellent in five patients and good in four and the average DASH score was 22.8. The scapholunate interval was 2.1 mm and scapholunate angle was 51°. Conclusion: The clinical and radiological results of the isolated volar surgical approach were satisfactory. The dorsal approach was not needed for reduction of dislocations during operations. Our results showed that an isolated volar approach was adequate. PMID

  20. Joint assembly

    NASA Technical Reports Server (NTRS)

    Wilson, Andrew (Inventor); Punnoose, Andrew (Inventor); Strausser, Katherine (Inventor); Parikh, Neil (Inventor)

    2010-01-01

    A joint assembly is provided which includes a drive assembly and a swivel mechanism. The drive assembly features a motor operatively associated with a plurality of drive shafts for driving auxiliary elements, and a plurality of swivel shafts for pivoting the drive assembly. The swivel mechanism engages the swivel shafts and has a fixable element that may be attached to a foundation. The swivel mechanism is adapted to cooperate with the swivel shafts to pivot the drive assembly with at least two degrees of freedom relative to the foundation. The joint assembly allows for all components to remain encased in a tight, compact, and sealed package, making it ideal for space, exploratory, and commercial applications.