Science.gov

Sample records for ac joint dislocation

  1. Temporomandibular joint dislocation.

    PubMed

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

    2015-01-01

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

  2. Temporomandibular joint dislocation

    PubMed Central

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

    2015-01-01

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

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

    PubMed Central

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

    2015-01-01

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

  4. 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. PMID:18836701

  5. Sideline Management of Joint Dislocations.

    PubMed

    Schupp, Christian M; Rand, Scott E; Hanson, Travis W; Lee, Bryan M; Jafarnia, Korsh; Jia, Yuhang; Moseley, J Bruce; Seaberg, John P; Seelhoefer, Gregory M

    2016-01-01

    Athletes can sustain a large variety of injuries from simple soft tissue sprains to complex fractures and joint dislocations. This article reviews and provides the most recent information for sports medicine professionals on the management of simple and complex joint dislocations, i.e., irreducible and/or associated with a fracture, from the sidelines without the benefit of imaging. For each joint, the relevant anatomy, common mechanisms, sideline assessment, reduction techniques, initial treatment, and potential complications will be discussed, which allow for the safe and prompt return of athletes to the field of play. PMID:27172077

  6. A Posteriorly Displaced Distal Metaphyseal Clavicular Fracture (Type IV AC Joint Dislocation-Like) in Children: A Case Report and Literature Review Study.

    PubMed

    Kotb, Ahmed; Yong, Taylor; Abdelgawad, Amr

    2016-01-01

    Fractures of the lateral end of the clavicle are common in pediatric patients; most of these fractures occur at the physeal level representing Salter Harris injuries. The vast majority of fractures of the lateral end of the clavicle are managed nonoperatively. In this report, we describe a unique type of fracture of the distal end of the clavicle in the pediatric patients in which the fracture occurs in the metaphyseal lateral clavicle with the proximal edge of the fracture displaced posteriorly through the trapezius muscle causing obvious deformity. It is similar in pathology to type IV AC joint dislocation. In this study we report this injury in eleven-year-old boy. Literature review showed that similar injuries were described before three times (two of them in pediatric patients). Due to the significant clinical deformity of this category with entrapment of the bone through the trapezius muscle, reduction (open or closed) of the fracture is the recommended treatment. PMID:26904336

  7. A Posteriorly Displaced Distal Metaphyseal Clavicular Fracture (Type IV AC Joint Dislocation-Like) in Children: A Case Report and Literature Review Study

    PubMed Central

    Kotb, Ahmed; Yong, Taylor; Abdelgawad, Amr

    2016-01-01

    Fractures of the lateral end of the clavicle are common in pediatric patients; most of these fractures occur at the physeal level representing Salter Harris injuries. The vast majority of fractures of the lateral end of the clavicle are managed nonoperatively. In this report, we describe a unique type of fracture of the distal end of the clavicle in the pediatric patients in which the fracture occurs in the metaphyseal lateral clavicle with the proximal edge of the fracture displaced posteriorly through the trapezius muscle causing obvious deformity. It is similar in pathology to type IV AC joint dislocation. In this study we report this injury in eleven-year-old boy. Literature review showed that similar injuries were described before three times (two of them in pediatric patients). Due to the significant clinical deformity of this category with entrapment of the bone through the trapezius muscle, reduction (open or closed) of the fracture is the recommended treatment. PMID:26904336

  8. Atraumatic Anterior Dislocation of the Hip Joint

    PubMed Central

    Ohtsuru, Tadahiko; Morita, Yasuyuki; Murata, Yasuaki; Itou, Junya; Morita, Yuji; Munakata, Yutaro; Kato, Yoshiharu

    2015-01-01

    Dislocation of the hip joint in adults is usually caused by high-energy trauma such as road traffic accidents or falls from heights. Posterior dislocation is observed in most cases. However, atraumatic anterior dislocation of the hip joint is extremely rare. We present a case of atraumatic anterior dislocation of the hip joint that was induced by an activity of daily living. The possible causes of this dislocation were anterior capsule insufficiency due to developmental dysplasia of the hip, posterior pelvic tilt following thoracolumbar kyphosis due to vertebral fracture, and acetabular anterior coverage changes by postural factor. Acetabular anterior coverage changes in the sagittal plane were measured using a tomosynthesis imaging system. This system was useful for elucidation of the dislocation mechanism in the present case. PMID:26819791

  9. All arthroscopic stabilization of acute acromioclavicular joint dislocation with fiberwire and endobutton system

    PubMed Central

    Spoliti, Marco; De Cupis, Mauro; Via, Alessio Giai; Oliva, Francesco

    2014-01-01

    Summary Introduction: acromioclavicular (AC) joint dislocation is common in athletes and in contact sports and about 9% of shoulder injuries involves this joint. The majority of these AC lesions can be successfully treated conservatively but high grade dislocation and some cases of type III dislocation need a surgical treatment. Many different operative techniques have been described over the years. The purpose of this study is to evaluate the results of arthroscopic stabilization of AC joint dislocation with TightRope® system. Materials and methods: nineteen patients with acute AC dislocation were treated by arthroscopic fixation with TightRope® system. Any associated lesions were repaired. All patients were assessed before surgery (T0), at 3 months (T1), at 6 months (T2) and at 1 year after the surgery (T3) using a visual analogic scale (VAS) and Constant-Murley Score (CMS). All patients were evaluated with X-ray. Results: six AC-joint dislocations involved the right shoulder and thirteen the left shoulder. Ten were type III dislocation, three were type IV and six were type V dislocation. We found a statistically significant reduction of pain (p< 0.01) at T1 compared to the pretreatment scores. The CMS measures showed an improvement between T1, T2 and T3, but the difference was statistically significant only between T1 and T3 (p= 0.017). The postoperative X-Ray of the shoulder showed a good reduction of the AC joint dislocation. We had 1 case of recurrence and 2 cases of loss of intraoperative reduction. Conclusion: arthroscopic technique for acute AC joint dislocations with the use of the TightRope® device is minimally invasive and it allows an anatomic restoration of the joint. It is a safe and effective procedure ensuring stable AC joint reconstruction and good cosmetic results. PMID:25767774

  10. Dislocation

    MedlinePlus

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

  11. 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

  12. Intrauterine temporomandibular joint dislocation: prenatal sonographic evaluation.

    PubMed

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

    2014-09-01

    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

  13. Dislocations

    MedlinePlus

    Dislocations are joint injuries that force the ends of your bones out of position. The cause is often a fall or a blow, sometimes from playing a contact sport. You can dislocate your ankles, knees, shoulders, hips, elbows and jaw. You can also dislocate your finger and toe joints. Dislocated joints often are ...

  14. Temporomandibular joint dislocation: experiences from Zaria, Nigeria

    PubMed Central

    Fomete, Benjamin; Obiadazie, Athanasius Chukwudi; Idehen, Kelvin; Okeke, Uche

    2014-01-01

    Objectives Dislocation of the temporomandibular joint may occur for various reasons. Although different invasive methods have been advocated for its treatment, this study highlights the value of non-invasive treatment options even in chronic cases in a resource-poor environment. Materials and Methods A seven-year retrospective analysis of all patients managed for temporomandibular joint dislocation in our department was undertaken. Patient demographics, risk factors associated with temporomandibular joint dislocation and treatment modalities were retrieved from patient records. Results In all, 26 patients were managed over a seven-year period. Males accounted for 62% of the patients, and yawning was the most frequent etiological factor. Conservative treatment methods were used successfully in 86.4% of the patients managed. Two (66.7%) of the three patients who needed surgical treatment developed complications, while only one (5.3%) patient who was managed conservatively developed complications. Conclusion Temporomandibular joint dislocation appears to be associated with male sex, middle age, yawning, and low socio-economic status, although these observed relationships were not statistically significant. Non-invasive methods remain an effective treatment option in this environment in view of the low socio-economic status of the patients affected. PMID:25045637

  15. Locked volar distal radioulnar joint dislocation

    PubMed Central

    Bouri, Fadi; Fuad, Mazhar; Elsayed Abdolenour, Ayman

    2016-01-01

    Introduction Volar dislocation of the distal radioulnar joint is a rare injury which is commonly missed in the emergency departments. A thorough review of literature showed very few reported cases and the cause for irreducibility varied in different cases, Lack of suspicion and improper X-ray can delay the diagnosis. Case presentation Our article discusses a case 40 year old construction worker, who presented to the Emergency with work-related injury, complaining of left wrist pain, deformity and inability to rotate his forearm. X-rays revealed a volar dislocation of distal ulna which was reducible after manipulation under General Anesthesia (GA). The joint was stable after the reduction. Discussion Isolated dislocation of the distal radioulnar joint can be either volar or dorsal, although dorsal dislocation is more common. The distal radioulnar articulation plays an important role in the rotational movement of the forearm. It allows pronation and supination which are essential for the function of the upper limb. Pronator Quadratus muscle spasm is an important blockade to reduction and was preventing reduction in this case. Methods The work has been reported in line with the CARE criteria [9]. Conclusion Volar locked dislocation of Distal Radio ulnar joint is a rare injury. High degree of clinical suspicion and proper X-ray is required for prompt detection. The importance of this case is to raise the awareness among physicians in treating these kind of injuries by careful assessment of the patient and radiographs, and to consider pronator quadratus as an important cause for the blockade to reduction. PMID:27016647

  16. Metatarsal Shaft Fracture with Associated Metatarsophalangeal Joint Dislocation.

    PubMed

    Tung, Taranjit Singh

    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

  17. 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

  18. Stochastic Dynamics of DC and AC Driven Dislocation Kinks

    NASA Astrophysics Data System (ADS)

    Vardanyan, A.; Kteyan, A.

    2013-02-01

    Dynamics of a pinned dislocation kink controlled by the acting DC and AC forces is studied analytically. The motion of the kink, described by sine-Gordon (sG) equation, is explored within the framework of McLaughlin-Scott perturbation theory. Assuming weakness of the acting AC force, the equation of motion of the dislocation kink in the pinning potential is linearized. Based on the equations derived, we study stochastic behavior of the kink, and determine the probability of its depinning. The dependencies of the depinning probability on DC and AC forces are analyzed in detail.

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

    PubMed

    Matchin, Bruce; Yee, Bruce; Mott, Timothy

    2016-04-01

    When not considering the grade of acromioclavicular (AC) joint dislocation, both conservative and surgical management lead to positive outcomes, although surgically managed patients require more time out of work. PMID:27262254

  20. Type IV acromioclavicular joint dislocation associated with a mid-shaft clavicle malunion

    PubMed Central

    Mohammed, Khalid D.; Stachiw, Danielle; Malone, Alex A.

    2016-01-01

    This reports presents the case of a combined clavicle fracture malunion and chronic Type IV acromioclavicular (AC) joint dislocation. The patient was seen acutely in the emergency department following a mountain bike accident at which time the clavicle fracture was identified and managed conservatively however the AC dislocation was not diagnosed. The patient presented 25 months following the injury with persistent pain and disability and was treated with clavicle osteotomy and AC stabilization. We document the clinical details, surgical treatment and outcome. PMID:26980988

  1. Type IV acromioclavicular joint dislocation associated with a mid-shaft clavicle malunion.

    PubMed

    Mohammed, Khalid D; Stachiw, Danielle; Malone, Alex A

    2016-01-01

    This reports presents the case of a combined clavicle fracture malunion and chronic Type IV acromioclavicular (AC) joint dislocation. The patient was seen acutely in the emergency department following a mountain bike accident at which time the clavicle fracture was identified and managed conservatively however the AC dislocation was not diagnosed. The patient presented 25 months following the injury with persistent pain and disability and was treated with clavicle osteotomy and AC stabilization. We document the clinical details, surgical treatment and outcome. PMID:26980988

  2. Simultaneous closed dislocation of both interphalangeal joints in one finger.

    PubMed

    Ron, D; Alkalay, D; Torok, G

    1983-01-01

    A rare case of simultaneous dislocation of both interphalangeal joints in one finger in a table-tennis player is presented. The second dislocation took place when the first dislocated joint became the fixed part of the finger as it hit a wall. Treatment was, first, hyperextension to unlock the base of the phalanx, then traction along the phalanx: its base was then pushed into contact with the head of the proximal phalanx. Splinting was applied with the joint in slight flexion. PMID:6823005

  3. Dislocation of the Temporomandibular Joint and Relocation Procedures.

    PubMed

    White, Thomas; Hedderick, Viki; Ramponi, Denise R

    2016-01-01

    Temporomandibular joint (TMJ) dislocation requires prompt medical attention due to the crucial impact of airway, nutrition acquisition, and communication. Recognition of this injury by the practitioner, based on clinical presentation and history, is paramount for identification of accurate diagnosis and prompt treatment of TMJ dislocation. Relocation or reduction methods vary on the basis of the severity of the injury and whether it is an acute or chronic dislocation. PMID:27482989

  4. 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

  5. Arthroscopic treatment of acute and chronic acromioclavicular joint dislocation.

    PubMed

    Lafosse, Laurent; Baier, Gloria P; Leuzinger, Jan

    2005-08-01

    This article presents an all-arthroscopic technique for coracoclavicular ligament reconstruction by ligamentoplasty after acute or chronic acromioclavicular joint dislocation. A coracoacromial ligament transfer is done to reconstruct the torn coracoclavicular ligaments, similar to open surgery. The coracoacromial ligament is dissected from the undersurface of the acromion and is reinserted on the inferior clavicle by transosseous suture fixation. Additional wire or screw stabilization may be used. With this method, we achieve a very satisfactory reduction of the dislocated acromioclavicular joint. PMID:16086572

  6. 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

  7. First Carpometacarpal Joint Dislocation and Review of Literatures

    PubMed Central

    Lahiji, Farivar; Zandi, Reza; Maleki, Arash

    2015-01-01

    Dislocation of the first carpometacarpal (CMC) is a rare occurrence. Treatment of this dislocation varies from closed reduction and casting to ligament repair. Neglected dislocation or incomplete reduction of the 1st CMC cause chronic instability and painful arthritis, muscle imbalance and decreased grip force. In our study 6 patients is evaluated that were visited in less than 24 hours from their injury. All were primarily reduced and except one patient later injured ligament were repaired. All patient after 6 months had normal range of motion without pain and they had not any complaint. Stability at the 1st CMC joint is dependent on static and dynamic forces. However, dislocation of the 1st CMC occur rare, but important function of the thumb specially in gripping and grasping makes it a significant problem. Injured ligament should repair for increased stability of 1st CMC joint, because neglected dislocation or incomplete reduction cause chronic instability and painful arthritis. PMID:26550598

  8. [Volar dislocation of the fifth carpometacarpal joint: a case report].

    PubMed

    Tsepelidis, D; Schuind, F

    2014-06-01

    Pure carpo-metacarpal dislocations without any fracture are rare, their volar component is exceptional. Untreated injuries can result in instability and early articular degeneration. We report a 72-year-old female patient who underwent an isolated closed volar dislocation of her fifth finger carpo-metacarpal joint after a fall. The clinical examination showed a 10°-defect in rotation with limited adduction (radial deviation). The X-rays showed a gap between the base of the fourth and the fifth metacarpal bones with volar dislocation of the base of the fifth carpometacarpal joint. The dislocation was successfully treated by closed reduction maintained with two K-wires. Immobilisation of the joint was applied for 6 weeks. At 2 years follow-up evaluation, the patient was pain free with no clinico-radiological evidence of instability and had returned to her previous level of activity. PMID:24880606

  9. Simultaneous dislocation of both interphalangeal joints in the middle finger.

    PubMed

    Hester, Thomas; Mahmood, Shoib; Morar, Yateen; Singh, Ravi

    2015-01-01

    Simultaneous dorsal dislocation of both interphalangeal joints (IPJs) in one finger is an uncommon injury. This injury usually occurs on the ulnar side of the hand involving ring and little fingers. We report a case of simultaneous dislocation of both IPJs in the middle finger. Closed reduction and splinting with the IPJs in extension provided a good result with full range of motion at the patient's final follow-up. PMID:25979959

  10. Subtle radiographic findings of acute, isolated distal radioulnar joint dislocation.

    PubMed

    Duryea, Dennis M; Payatakes, Alexander H; Mosher, Timothy J

    2016-09-01

    Distal radioulnar dislocations typically occur in association with fractures of the distal radius and/or ulna. Rare isolated dislocations or subluxations are more difficult to diagnose and are initially missed in up to 50 % of cases. We present two cases of missed isolated volar rotatory dislocation of the distal radioulnar joint. Subtle, overlooked radiographic findings of abnormal radioulnar alignment and ulnar styloid projection are highlighted. The supplemental role of cross-sectional imaging is reviewed. Adequate clinical information, appropriate radiographic technique, and high index of suspicion are necessary for the accurate and timely diagnosis of this rare injury pattern. PMID:27229875

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

    PubMed

    Wollstein, Ronit; Michael, Dafna; Harel, Hani

    2016-01-01

    Surgical arthroplasty of thumb carpometacarpal (CMC) joint osteoarthritis is commonly performed. Postoperative therapeutic protocols aim to improve range of motion and function of the revised thumb. We describe a case in which the thumb CMC joint had been chronically dislocated before surgery, with shortening of the soft-tissue dynamic and static stabilizers of the joint. The postoperative protocol addressed the soft tissues using splinting and exercises aimed at lengthening and strengthening these structures, with good results. It may be beneficial to evaluate soft-tissue tension and the pattern of thumb use after surgery for thumb CMC joint osteoarthritis to improve postoperative functional results. PMID:26709434

  12. Arthroscopically Assisted Treatment of Acute Dislocations of the Acromioclavicular Joint

    PubMed Central

    Braun, Sepp; Beitzel, Knut; Buchmann, Stefan; Imhoff, Andreas B.

    2015-01-01

    Arthroscopically assisted treatments for dislocations of the acromioclavicular joint combine the advantages of exact and visually controlled coracoid tunnel placement with the possibility of simultaneous treatment of concomitant injuries. The clinical results of previous arthroscopically assisted techniques have been favorable at midterm and long-term follow-up. The presented surgical technique combines the advantages of arthroscopically positioned coracoclavicular stabilization with an additional suture cord cerclage of the acromioclavicular joint capsule for improved horizontal stability. PMID:26870646

  13. Arthroscopic treatment of acute acromioclavicular joint dislocation with double flip button.

    PubMed

    Murena, L; Vulcano, Ettore; Ratti, C; Cecconello, L; Rolla, P R; Surace, M F

    2009-12-01

    The ideal treatment for acute acromioclavicular joint dislocation is still controversial, both in terms of indications and surgical technique. The clinical and radiographic outcomes of 16 patients affected by acute AC joint dislocation (type III-V) and arthroscopically treated with a coracoclavicular double flip button are presented. Despite the excellent clinical results both in terms of Constant score (mean 97 points) and patient satisfaction, at a mean follow-up of 31 months the radiographs showed partial loss of reduction due to distal migration of the flip button within the upper third of the clavicle in one-fourth of the cases. The technique presented here proved to be safe and minimally invasive while delivering good aesthetic results and allowing for the treatment of associated lesions. Furthermore, the technique could benefit from more advanced retention devices, which ought to reduce or avoid migration of the flip buttons. PMID:19554311

  14. Dorsal dislocation of the trapezoid at the scaphotrapeziotrapezoidal joint.

    PubMed

    Ricciardi, Benjamin F; Malliaris, Stephanie; Weiland, Andrew J

    2015-05-01

    Background Axial dislocations of the trapezoid are rare, high-energy injuries. We present an unusual case of isolated dorsal dislocation of the trapezoid and index metacarpal at the scaphotrapeziotrapezoidal (STT) joint due to steering wheel injury. Case Description A 56-year-old man presented to our office with right hand pain for 10 days after a head-on motor vehicle accident (MVA) in which he suffered an axial load injury to his hand on the steering wheel. X-ray images were reported as unremarkable. Further workup with computed tomography (CT) scan revealed an isolated dorsal dislocation of the trapezoid with its associated index metacarpal at the STT joint. The patient was treated with open reduction, pinning, and dorsal capsulodesis. Literature Review Dorsal dislocation of the trapezoid has been associated with high-energy trauma such as industrial accidents or motorcycle accidents; however, recent case reports have also revealed an axial loading mechanism from a steering wheel injury as an increasingly common mechanism. These cases typically occur concomitantly with other fractures or dislocations of the carpal bones or carpometacarpal (CMC) joints. Multiple reports of delayed diagnoses due to distracting injuries and difficulty of recognition on plain radiographs have been reported. Clinical Relevance Dorsal dislocation of the trapezoid with its associated second metacarpal is a rare, high-energy injury that can often be missed on plain radiography. We report a rare variant with no concomitant injury to the metacarpals or carpal bones. A low index of suspicion for further imaging should exist in the setting of an axial loading injury to the hand. PMID:25945300

  15. 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

  16. 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 acetaminophen for pain. Think Prevention! Make sure kids wear the appropriate safety gear ...

  17. Fracture dislocation of carpometacarpal joints: a missed injury.

    PubMed

    Gaheer, Rajinder Singh; Ferdinand, Rupert D

    2011-05-01

    Fracture dislocation of the carpometacarpal joints on the ulnar side of the hand is an uncommon injury. These are high-energy injuries seen in motorcyclists and boxers. The mechanism of injury involves violent, forceful dorsiflexion of the wrist combined with longitudinal impact on the closed hand. This article reports a case of fracture of the base of the middle finger with dislocation of the ring and little finger carpometacarpal joints. On first examination, a diagnosis of isolated, minimally-displaced, middle-metacarpal base fracture was made and deemed suitable for nonoperative management. The hand was splinted in a plaster-of-Paris slab. Later, a true lateral radiograph showed the exact nature of the injury. The fracture was successfully treated with closed reduction under general anesthesia and transfixation using Kirschner wires. Functional results were excellent with return to work at 10 weeks and excellent grip strength at 14 weeks. This injury may be missed in an acute setting in a busy accident and emergency unit. Swelling around the wrist with shortening of the knuckle should alert the clinician towards the possibility of such an injury. On routine anteroposterior view, overlap of joint surfaces, loss of parallelism, and asymmetry at the carpometacarpal joints should raise suspicion of the possibility of a subtle carpometacarpal injury. This article highlights the importance of a high index of suspicion, a true lateral radiograph, and careful evaluation of radiographs in diagnosing these injuries. Intensive postoperative physiotherapy is vital to achieving a satisfactory outcome. PMID:21598884

  18. Comparison of Results between Hook Plate Fixation and Ligament Reconstruction for Acute Unstable Acromioclavicular Joint Dislocation

    PubMed Central

    Yoon, Jong Pil; Lee, Byoung-Joo; Nam, Sang Jin; Chung, Seok Won; Jeong, Won-Ju; Min, Woo-Kie

    2015-01-01

    Background In the present study, we aimed to compare clinical and radiographic outcomes between hook plate fixation and coracoclavicular (CC) ligament reconstruction for the treatment of acute unstable acromioclavicular (AC) joint dislocation. Methods Forty-two patients who underwent surgery for an unstable acute dislocation of the AC joint were included. We divided them into two groups according to the treatment modality: internal fixation with a hook plate (group I, 24 cases) or CC ligament reconstruction (group II, 18 cases). We evaluated the clinical outcomes using a visual analog scale (VAS) for pain and Constant-Murley score, and assessed the radiographic outcomes based on the reduction and loss of CC distance on preoperative, postoperative, and final follow-up plain radiographs. Results The mean VAS scores at the final follow-up were 1.6 ± 1.5 and 1.3 ± 1.3 in groups I and II, respectively, which were not significantly different. The mean Constant-Murley scores were 90.2 ± 9.9 and 89.2 ± 3.5 in groups I and II, respectively, which were also not significantly different. The AC joints were well reduced in both groups, whereas CC distance improved from a mean of 215.7% ± 50.9% preoperatively to 106.1% ± 10.2% at the final follow-up in group I, and from 239.9% ± 59.2% preoperatively to 133.6% ± 36.7% at the final follow-up in group II. The improvement in group I was significantly superior to that in group II (p < 0.001). Furthermore, subluxation was not observed in any case in group I, but was noted in six cases (33%) in group II. Erosions of the acromion undersurface were observed in 9 cases in group I. Conclusions In cases of acute unstable AC joint dislocation, hook plate fixation and CC ligament reconstruction yield comparable satisfactory clinical outcomes. However, radiographic outcomes based on the maintenance of reduction indicate that hook plate fixation is a better treatment option. PMID:25729525

  19. 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. PMID:8572795

  20. Dorsal Buttress Plate Fixation of Ulnar Carpometacarpal Joint Fracture Dislocations.

    PubMed

    Tan, En Si; Chao, Tay Shian

    2016-06-01

    We propose a method for open reduction and internal fixation of early and unstable ulnar (fourth and/or fifth) carpometacarpal joint (CMCJ) fracture subluxations or dislocations using a dorsal buttress plate. In ulnar CMCJ fracture dislocations, the metacarpal has a tendency to displace dorsally and proximally when there is an axial load. Using the dorsal buttress plate method of fixation, a plate is fixed proximally to the hamate, aligned parallel and dorsal to the metacarpal to act as a buttress, to resist this movement. To preserve the fourth and the fifth CMCJ mobility, the distal end of the plate is not fixed to the metacarpal base. We illustrate the use of this technique on 4 patients who had different patterns of injury at the ulnar CMCJ. All patients regained excellent range of motion and function. None of the patients had redisplacement or nonunion of fracture. The dorsal buttress plate is a viable option for fixation of early and unstable ulnar CMCJ fracture subluxations or dislocations. PMID:27077465

  1. Suture rupture in acromioclavicular joint dislocations treated with flip buttons.

    PubMed

    Motta, Pierorazio; Maderni, Alberto; Bruno, Laura; Mariotti, Umberto

    2011-02-01

    Acute acromioclavicular joint dislocations (ACDs) may be treated arthroscopically with flip buttons. This extra-articular fixation is easy to implant and is well tolerated. Between 2007 and 2009, 20 ACD patients (2 women and 18 men; mean age, 32 years) had surgery by the arthroscopic TightRope technique (Arthrex, Naples, FL). The main complication of this technique that has been reported is the partial loss of reduction at follow-up due to clavicular osteolysis under the superior flip button. We describe 4 cases with loss of reduction due to rupture of the sutures running across the buttons: 2 women with joint hyperlaxity and acute Rockwood grade IV ACD and 2 men, heavy manual workers, with joint hyperlaxity and acute Rockwood grade IV ACD. The use of flip buttons might not be indicated in patients with joint hyperlaxity because they are able to obtain immediate stability only on the vertical plane and not on the horizontal plane. Anteroposterior movements of the acromioclavicular joint might rub the suture against the bone tunnels leading to wear and cutting. PMID:21266279

  2. Simultaneous dislocation of radiocapitellar and distal radioulnar joint.

    PubMed

    Nishi, Tomio; Suzuki, Noriyuki; Tani, Takayuki; Aonuma, Hiroshi

    2013-01-01

    A 45-year-old male presented to the emergency room of our institution complaining of severe pain around the left elbow. While playing volleyball, he slipped down with his left arm hit between the floor and his body. He complaind of strong pain from left elbow to hand, and active motion of elbow and wrist joint was impossible. His forearm was held in supinated position. On X-ray examination, radius head was deviated to anterior lateral side, and distal end of radius was dislocated to dorsal side. Tenderness was prominent at the site of radial head and distal radioulnar joint. Surgical treatment was performed using triceps tendon strip. Good functional recovery was gained. PMID:24194995

  3. Cervical facet joint kinematics during bilateral facet dislocation

    PubMed Central

    Panjabi, Manohar M.; Simpson, Andrew K.; Pearson, Adam M.; Tominaga, Yasuhiro; Yue, James J.

    2007-01-01

    Previous biomechanical models of cervical bilateral facet dislocation (BFD) are limited to quasi-static loading or manual ligament transection. The goal of the present study was to determine the facet joint kinematics during high-speed BFD. Dislocation was simulated using ten cervical functional spinal units with muscle force replication by frontal impact of the lower vertebra, tilted posteriorly by 42.5°. Average peak rotations and anterior sliding (displacement of upper articulating facet surface along the lower), separation and compression (displacement of upper facet away from and towards the lower), and lateral shear were determined at the anterior and posterior edges of the right and left facets and statistically compared (P < 0.05). First, peak facet separation occurred, and was significantly greater at the left posterior facet edge, as compared to the anterior edges. Next, peak flexion rotation and anterior facet sliding occurred, followed by peak facet compression. The highest average facet translation peaks were 22.0 mm for anterior sliding, 7.9 mm for separation, 9.9 mm for compression and 3.6 mm for lateral shear. The highest average rotation of 63° occurred in flexion, significantly greater than all other directions. These events occurred, on average, within 0.29 s following impact. During BFD, the main sagittal motions included facet separation, flexion rotation, anterior sliding, followed by compression, however, non-sagittal motions also existed. These motions indicated that unilateral dislocation may precede bilateral dislocation. PMID:17566792

  4. 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

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

    PubMed Central

    Marchie, Anthony; Kumar, Arun; Catre, Melanio

    2009-01-01

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

  6. Dislocation of the distal radioulnar joint associated with a transstyloid radiocarpal fracture dislocation. A case report and review of the literature.

    PubMed

    Stoffelen, D; Fortems, Y; De Smet, L; Broos, P

    1996-03-01

    Dislocations of the distal radio-ulnar joint (DRUJ) can be isolated or combined with fractures. Cases of DRUJ dislocations have been described with Galleazi fractures, open radius and ulna fractures and intraarticular fractures of the distal radius. We report a case of a volar DRUJ dislocation combined with a transstyloid radio-carpal dislocation. Because of severe instability of the wrist, open reduction of the radial styloid combined with an open reduction of the dislocated DRUJ is advised. PMID:8669257

  7. Treatment of Rockwood type III acromioclavicular joint dislocation using autogenous semitendinosus tendon graft and endobutton technique

    PubMed Central

    Ye, Gang; Peng, Chao-An; Sun, Hua-Bin; Xiao, Jing; Zhu, Kang

    2016-01-01

    Background The aim of this study was to evaluate the therapeutic effect of autogenous semitendinosus graft and endobutton technique, and compare with hook plate in treatment of Rockwood type III acromioclavicular (AC) joint dislocation. Methods From April 2012 to April 2013, we treated 46 patients with Rockwood type III AC joint dislocation. Patients were randomly divided into two groups: Group A was treated using a hook plate and Group B with autogenous semitendinosus graft and endobutton technique. All participants were followed up for 12 months. Radiographic examinations were performed every 2 months postoperatively, and clinical evaluation was performed using the Constant–Murley score at the last follow-up. Results Results indicated that patients in Group B showed higher mean scores (90.3±5.4) than Group A (80.4±11.5) in terms of Constant–Murley score (P=0.001). Group B patients scored higher in terms of pain (P=0.002), activities (P=0.02), range of motion (P<0.001), and strength (P=0.004). In Group A, moderate pain was reported by 2 (8.7%) and mild pain by 8 (34.8%) patients. Mild pain was reported by 1 (4.3%) patient in Group B. All patients in Group B maintained complete reduction, while 2 (8.7%) patients in Group A experienced partial reduction loss. Two patients (8.7%) encountered acromial osteolysis on latest radiographs, with moderate shoulder pain and limited range of motion. Conclusion Autogenous semitendinosus graft and endobutton technique showed better results compared with the hook plate method and exhibited advantages of fewer complications such as permanent pain and acromial osteolysis. PMID:26811685

  8. Simultaneous Volar Dislocations of Carpometacarpal and Metacarpophalangeal Joints of the Thumb

    PubMed Central

    Khan, Hayat; Darcy, Peter; Magnussen, Peter

    2012-01-01

    Introduction: Multiple dislocations of joints in the hand are rare. Double dislocations of the thumb joints have only been reported on four previous occasions, in all cases reported to date, the joints have dislocated dorsally. Case Report: We present the case of a 26-year-old male patient with simultaneous volar dislocations of the carpometacarpal and metacarpophalangeal joints of the thumb. There was delayed operative treatment of this injury with ligament reconstruction and stabilization of the metacarpophalangeal joint. Conclusions: This rare case provides a mechanism to this type of injury, highlights the importance of initial, and repeated clinical and radiographic review, highlights the soft tissue component to this injury, and demonstrates how even delayed treatment can result in a good functional outcome.

  9. Recurrent posttraumatic trapeziometacarpal joint dislocation in a child: A case report.

    PubMed

    Gaillard, Julien; Fitoussi, Franck

    2016-04-01

    Traumatic trapeziometacarpal joint dislocation of the thumb accounts for less than 1% of all hand injuries. This injury is even less common in children. Optimal treatment strategies for this injury are still the subject of debate for both children and adults. We report a case of recurrent posttraumatic trapeziometacarpal joint dislocation in an eight-year-old girl. We believe our case is the first report of recurrent acute dislocation leading to chronic dislocation in the English medical literature. Restoring the anatomy and biomechanics of the trapeziometacarpal joint is essential when treating these injuries; for this reason, surgical treatment is usually indicated. Overall, the prognosis of trapeziometacarpal dislocation treated acutely is favorable and stable over time. However, the role of open surgery and ligament reconstruction remains controversial, especially in children. PMID:27117129

  10. Volar dislocation of the thumb metacarpophalangeal joint with acute repair of the ulnar collateral ligament

    PubMed Central

    Potini, Vishnu C.; Sood, Amit; Sood, Aditya; Mastromonaco, Edward

    2014-01-01

    Abstract Volar dislocations of the thumb metacarpophalangeal joint are uncommon and can be associated with rupture of the ulnar collateral ligament (UCL). We report a case where a volar thumb dislocation was successfully closed reduced, but instability required open repair of the UCL. Early motion protocol helped achieve favorable results.

  11. Ligamentous Reconstruction of Traumatic Dislocation of Thumb Carpometacarpal Joint: Case Report and Review of Literature

    PubMed Central

    Annappa, Rajendra; Kotian, Prem; P, Janardhana Aithala; Mudiganty, Srikanth

    2015-01-01

    Introduction: Thumb carpometacarpal dislocation is a rare injury with many treatment options described in literature. Case Description: A 47-year-old male patient presented to hospital with an isolated dorsal dislocation of the thumb carpometacarpal joint. Closed reduction of the dislocation could be easily done but joint was grossly unstable and redislocated. Repair of ruptured dorsoradial ligament and joint capsule was done with immobilization for 6 weeks. At 2-years follow-up evaluation, the patient was pain free and returned to his previous level of activity. No restriction of carpometacarpal movements or residual instability was noticed. Radiographic examination showed normal joint congruity and no signs of osteoarthritis. Conclusion: Capsuloligamentous repair can be considered the treatment of choice in thumb carpometacarpal dislocations with instability after closed reduction.

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

    PubMed Central

    2011-01-01

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

  13. Surgical Treatment of Sternoclavicular Joint Dislocation Using a T-plate

    PubMed Central

    Hwang, Wan Jin; Lee, Yeiwon; Yoon, Yoo Sang; Kim, Young Jin; Ryu, Han Young

    2016-01-01

    A 22-year-old man was hospitalized with a sternoclavicular joint (SCJ) dislocation caused by a traffic accident. Surgical reduction and fixation of the SCJ were performed using a T-plate. SCJ dislocation is rare, accounting for less than 1% of all dislocations, and is usually treated conservatively, although severe cases may require surgery. Surgery typically involves joint reduction and fixation using an autologous tendon graft, but this has disadvantages such as the requirement for additional surgery to obtain autologous tissue and an extended operative time. To overcome these issues, here, we performed a simple SCJ reduction and fixation using a T-plate and achieved good results. PMID:27298805

  14. Treatment of acute temporomandibular joint dislocation using manipulation technique for disk displacement.

    PubMed

    Yabe, Tetsuji; Tsuda, Tomoyuki; Hirose, Shunsuke; Ozawa, Toshiyuki; Kawai, Katsuya

    2014-03-01

    Temporomandibular joint dislocation is not frequently encountered, but it is often difficult to reduce the dislocation with conventional methods described in textbooks. The key points to success of reduction depend on the patient's position, route of approach, and timing of reducing each side. We apply a manipulation technique for disk displacement to the reduction that corresponds to these key points. Using our method, temporomandibular joint dislocation can be easily reduced, without using sedative or analgesics. This method is simple, convenient, and worth trying in place of the conventional method. PMID:24621705

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

    PubMed Central

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

    2016-01-01

    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. PMID:27433301

  16. 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.

  17. Arthroscopic eminoplasty for habitual dislocation of the temporomandibular joint: preliminary study.

    PubMed

    Segami, N; Kaneyama, K; Tsurusako, S; Suzuki, T

    1999-12-01

    A unique surgical technique, arthroscopic eminoplasty was undertaken in 16 joints of 11 patients with habitual dislocation of the temporomandibular joint (TMJ). There were 10 joints with subluxation and 6 joints with complete dislocation in 4 male and 7 female patients with a mean age of 33 +/- 20 years. The procedure consisted of conventional diagnostic arthroscopy, followed by shaving of approximately 3 to 5 mm in height of the articular eminence with an electric motorized shaver with bone files, depending on the bone thickness as detected by preoperative imaging. The arthroscopic eminoplasty was accomplished without any peri- or postoperative complication. During the postoperative follow-up period of 19 months on average (6-36 months), all patients were free of dislocation of the TMJ, except for one joint. The patients could open their mouth 42 +/- 6 mm without arthralgia 2 weeks after surgery, and finally 47 +/- 7 mm without any subjective symptom but small joint noises (clicking or crepitus) in 10 joints. On postoperative radiographs only minor changes of the mandibular condyle were apparent in four joints. Arthroscopic eminoplasty might become a significant procedure for habitual dislocation of the TMJ and seems to produce results comparable to open arthrotomy. Further study will be required to assess this method as an acceptable modality in the future. PMID:10870759

  18. Anterior fracture dislocation of sacroiliac joint: A rare type of crescent fracture

    PubMed Central

    Trikha, Vivek; Singh, Vivek; Kumar, V Senthil

    2015-01-01

    Crescent fractures of the pelvis are usually described as posterior sacro iliac fracture dislocations. Rarely anterior displacement of the fractured iliac fragment along with dislocation has been reported in crescent fractures. Four cases of anterior fracture dislocation of the sacro iliac joint managed in the last two years by a single surgeon are presented. The injury mechanism, radiological diagnosis, management protocol along with functional outcomes of all the four patients have been discussed. CT scan is essential in the diagnosis and preoperative planning of this injury pattern. Early fixation along with proper reduction leads to excellent functional outcome in this subset of lateral compression injuries of the pelvis. PMID:26015619

  19. 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. PMID:24172655

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

    PubMed Central

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

    2014-01-01

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

  1. Dislocation

    MedlinePlus

    ... likely to happen again. Follow-up with an orthopedic surgeon is recommended after a dislocation. ... SE, Mehta A, Maddow C, Luber SD. Critical orthopedic skills and procedures. Emergency Medicine Clinics of North ...

  2. Bilateral Anterior Fracture-Dislocation of Shoulder Joint- A rare case with Delayed Presentation

    PubMed Central

    Sunku, Nithin; Kalaiah, Kiran; Marulasidappa, G.; Gopinath, P.

    2012-01-01

    Introduction: The shoulder is the most frequently dislocated joint. Bilateral glenohumeral dislocations are rare and almost always posterior. Bilateral anterior fracture dislocations of humeral neck in a patient with seizure are extremely rare. We report one such case of delayed presentation of bilateral anterior fracture dislocation of shoulder after an epileptic attack. Case Report: We describe a rare case of 30 year old gentleman who presented with first episode of seizure following alcohol withdrawal. Physical examination and radiographic assessment revealed fracture dislocation of bilateral proximal humeri (4 part fracture on right side and two part fracture on left). Patient presented 20 days after injury during which he was treated by local osteopath by immobilization and massage. Open reduction and internal fixation with simple T plate was done on right side and multiple K – wires were used on left side. At one year follow up the patient had acceptable range and was able to carry out daily activities. Conclusions: Bilateral anterior fracture dislocation of shoulder behave similar to unilateral fracture dislocations and treatment needs to be planned appropriately. Even in cases with delayed presentation good results can be achieved

  3. 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

  4. 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

  5. [Outcome after late reconstruction of dislocations of the acromioclavicular joint].

    PubMed

    Zilch, H; Steuer, H G; Friedebold, G

    1983-10-01

    In a total of 130 cases with a complete luxation of the acromioclavicular joint (Tossy III) which were treated operatively, there are included 29 cases with older injuries (6 to 28 months after accident). Late reconstruction were regarded only such cases which needed a plastic reconstruction of the lig. coracoclaviculare. An account is given of the 21 cases, followed up on an average of 5,6 years after the operation. The material for the plastic reconstruction was autologous and heterologous tendons, fascia lata, carbon-fibres-ligaments, and especially lyodura. The results are very satisfied regarding to the mobility and stability of the shoulder joints. But there was seen a high rate of arthrosis of the a.c.-joint, which causes are discussed as well as the opportunity to make an osteotomy of the clavicula to degress the pressure at this point. The arthrosis is only painful in cases with a simultaneous instability. PMID:6138966

  6. Bidirectional Dislocation of the Distal Radioulnar Joint After Distal Radius Fracture: Case Report.

    PubMed

    Arimitsu, Sayuri; Moritomo, Hisao

    2016-02-01

    We report a patient with bidirectional dislocation of the distal radioulnar joint after malunited distal radius fracture, in which the ulnar head dislocated dorsally during forearm pronation and palmarly during supination without manual compression of the ulnar head. The patient had chronic ulnar wrist pain and experienced a painful clunk during forearm rotation. The distal radioulnar joint ballottement test was positive in both the dorsal and palmar directions. Her distal radius was malunited with a 20° dorsal angulation and 18° pronation deformity. A corrective osteotomy of the radius with open repair of the triangular fibrocartilage complex foveal avulsion yielded success. At the 7-year follow-up, there was almost a normal range of wrist and forearm motion, 83% grip strength, no arthritis, and a stable distal radioulnar joint. PMID:26723478

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

    PubMed

    Takeuchi, Satoru; Takasato, Yoshio

    2011-09-01

    A 33-year-old man fell from a height and was referred to our hospital. Physical examination showed a swelling in the left preauricular region without laceration. No thrill or bruit was detected at this time. A face x-ray and a computed tomographic scan showed a left temporomandibular joint (TMJ) dislocation, Le Fort I fractures, and a mandibular body fracture. Left TMJ dislocation was treated by manual reduction. Two days after admission, a swelling in the left preauricular region progressed, with thrill and bruit. Left external carotid artery angiograms showed an arteriovenous fistula with a dilated pouch near the left TMJ. The fistula was fed by the left superficial temporal artery and drained into the left superficial temporal vein. The fistula was successfully embolized using Tornado coils. This is the first case of an arteriovenous fistula of the superficial temporal artery after manual reduction of TMJ dislocation. PMID:21959481

  8. Sternoclavicular joint dislocation and its management: A review of the literature

    PubMed Central

    Morell, Daniel J; Thyagarajan, David S

    2016-01-01

    Dislocations of the sternoclavicular joint (SCJ) occur with relative infrequency and can be classified into anterior and posterior dislocation, with the former being more common. The SCJ is inherently unstable due to its lack of articular contact and therefore relies on stability from surrounding ligamentous structures, such as the costoclavicular, interclavicular and capsular ligaments. The posterior capsule has been shown in several studies to be the most important structure in determining stability irrespective of the direction of injury. Posterior dislocation of the SCJ can be associated with life threatening complications such as neurovascular, tracheal and oesophageal injuries. Due to the high mortality associated with such complications, these injuries need to be recognised acutely and managed promptly. Investigations such as X-ray imaging are poor at delineating anatomy at the level of the mediastinum and therefore CT imaging has become the investigation of choice. Due to its rarity, the current guidance on how to manage acute and chronic dislocations is debatable. This analysis of historical and recent literature aims to determine guidance on current thinking regarding SCJ instability, including the use of the Stanmore triangle. The described methods of reduction for both anterior and posterior dislocations and the various surgical reconstructive techniques are also discussed. PMID:27114931

  9. 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. PMID:26114704

  10. Complete medial column dislocation at the cuneonavicular joint: an unusual Lisfranc-like injury.

    PubMed

    Schepers, T; de Jong, V M; Luitse, J S K

    2014-09-01

    Lisfranc injuries represent a wide spectrum of different injuries at the tarsometatarsal joint. Not all types fit the currently available classifications. This case illustrates a rare subtype of a Lisfranc injury, with a dislocation of the entire first ray. It is presented to create more awareness for midfoot injuries. This article reviews the literature and provides recommendations for the treatment of similar cases in the future. PMID:25063016

  11. 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

  12. Simultaneous Volar Dislocation of Distal Interphalangeal Joint and Volar Fracture-Subluxation of Proximal Interphalangeal Joint of Little Finger: A New Mechanism of Injury.

    PubMed

    Mozaffarian, Kamran; Bayatpour, Abdollah; Vosoughi, Amir Reza

    2016-10-01

    Simultaneous volar dislocation of distal interphalangeal (DIP) joint and volar fracture-subluxation of proximal interphalangeal (PIP) joint of the same finger has not been reported yet. A 19-year-old man was referred due to pain on the deformed left little finger after a ball injury. Radiographs showed volar dislocation of the DIP joint and dorsal lip fracture of the middle phalanx with volar subluxation of PIP joint of the little finger. This case was unique in terms of the mechanism of injury which was hyperflexion type in two adjacent joints of the same finger. The patient was treated by closed reduction of DIP joint dislocation and open reduction and internal fixation of the PIP joint fracture-subluxation and application of dorsal external fixator due to instability. Finally, full flexion of the PIP joint and full extension of the DIP joint were obtained but with 10 degree extension lag at the PIP joint and DIP joint flexion ranging from 0 degree to 30 degrees. Some loss of motion in small joints of the fingers after hyperflexion injuries should be expected. PMID:27595966

  13. Irreducible open dorsal dislocation of the proximal interphalangeal joint: a case report.

    PubMed

    Muraoka, Shizuka; Furue, Yukihiro; Kawashima, Mahito

    2010-01-01

    We report a rare case of open dorsal dislocation of the proximal interphalangeal joint which needed operative reduction. A 39-year-old man injured his right middle finger while playing baseball. There was a laceration on the proximal interphalangeal crease, and the condyles of the proximal phalanx protruded through the wound. The flexor tendons had slipped behind the radial condyle, and made reduction impossible. After the flexor tendons and volar plate were replaced back into their normal position, the reduction was successful. Finally, the patient had full and painless motion of the digit. We review the reported cases of this injury in the relevant literature. PMID:20422730

  14. Acroplate--a modern solution for the treatment of acromioclavicular joint dislocation.

    PubMed

    Cîrstoiu, C; Rădulescu, R; Popescu, D; Ene, R; Circotă, G; Bădiceanu, Corina

    2009-01-01

    Two main ways to fix the reduction were imposed in surgical treatment of the acromioclavicular joint dislocations: fixation with trans acromioclavicular pin (Phemister method) and fixation with plate and screws type acroplate. The purpose of the present paper work is to compare immediate and later postoperative results between the two types of surgical interventions. During 2005-2007, 37 surgical reductions and fixation of acromioclavicular joint dislocations were performed in the Orthopedic-Traumatology Clinic of SUUB. In 17 cases a fixation with screws and plates type acroplate has been performed and in 20 cases with pins using the Phemister method. Sex ratio: 31 men and 8 women. Patients were aged between 17 and 56 years old. Follow up at 6 weeks, 3, 6, 12 and 18 post-operatory months. Osteosintesis material removing was done postoperatively, at 4 weeks in case of acroplate's and at 6 weeks in case of the pins. All patients treated of fixation with plate and screws acroplate type had a favorable evolution/development, starting with the shoulder joint mobilization at 24 hours postoperatively, with a complete recovery 4 weeks after the operation, at the same time with the ablation, and without immediate other late complications. As far as the patients treated by using the Phemister method are concerned, they were applied an immobilization, postoperatively. Desault bandage or the scarf for a period between 1 and 3 weeks, beginning with the shoulder joint mobilization later on and a full recovery after a minimum of 6 weeks. However, 3 of the cases showed a migration of one or both pins. Following the study, a more rapid recovery resulted, complete, and without complications of mobility in the shoulder joint, when using plate type acroplate vs pin. PMID:20108536

  15. Coracoid Process Avulsion Fracture at the Coracoclavicular Ligament Attachment Site in an Osteoporotic Patient with Acromioclavicular Joint Dislocation

    PubMed Central

    Umemoto, Takahisa; Fukuda, Kimitaka; Kajino, Tomomichi

    2016-01-01

    Coracoid fractures are uncommon, mostly occur at the base or neck of the coracoid process (CP), and typically present with ipsilateral acromioclavicular joint (ACJ) dislocation. However, CP avulsion fractures at the coracoclavicular ligament (CCL) attachment with ACJ dislocation have not been previously reported. A 59-year-old woman receiving glucocorticoid treatment fell from bed and complained of pain in her shoulder. Radiographs revealed an ACJ dislocation with a distal clavicle fracture. Three-dimensional computed tomography (3D-CT) reconstruction showed a small bone fragment at the medial apex of the CP. She was treated conservatively and achieved a satisfactory outcome. CP avulsion fractures at the CCL attachment can occur in osteoporotic patients with ACJ dislocations. Three-dimensional computed tomography is useful for identifying this fracture type. CP avulsion fractures should be suspected in patients with ACJ dislocations and risk factors for osteoporosis or osteopenia. PMID:27493819

  16. Coracoid Process Avulsion Fracture at the Coracoclavicular Ligament Attachment Site in an Osteoporotic Patient with Acromioclavicular Joint Dislocation.

    PubMed

    Onada, Yoshihiro; Umemoto, Takahisa; Fukuda, Kimitaka; Kajino, Tomomichi

    2016-01-01

    Coracoid fractures are uncommon, mostly occur at the base or neck of the coracoid process (CP), and typically present with ipsilateral acromioclavicular joint (ACJ) dislocation. However, CP avulsion fractures at the coracoclavicular ligament (CCL) attachment with ACJ dislocation have not been previously reported. A 59-year-old woman receiving glucocorticoid treatment fell from bed and complained of pain in her shoulder. Radiographs revealed an ACJ dislocation with a distal clavicle fracture. Three-dimensional computed tomography (3D-CT) reconstruction showed a small bone fragment at the medial apex of the CP. She was treated conservatively and achieved a satisfactory outcome. CP avulsion fractures at the CCL attachment can occur in osteoporotic patients with ACJ dislocations. Three-dimensional computed tomography is useful for identifying this fracture type. CP avulsion fractures should be suspected in patients with ACJ dislocations and risk factors for osteoporosis or osteopenia. PMID:27493819

  17. Concomitant dislocation of the tarsometatarsal and metatarsophalangeal joints of the second toe (floating second metatarsal): a case report

    PubMed Central

    2009-01-01

    When examining patients with injuries of the tarsometatarsal joint, the physician must pay attention to the foot as a whole. An extremely rare foot injury has been described in which axial and compressive forces cause simultaneous dislocation of the tarsometatarsal joint and the metatarsophalangeal joint of the same or adjacent ray. The following is a report of one of these rare injuries. We will also discuss probable mechanism and diagnosis of this rare traumatic injury. PMID:19134219

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

    PubMed Central

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

    2014-01-01

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

  19. Functional outcome of tarsometatarsal joint fracture dislocation managed according to Myerson classification

    PubMed Central

    YU, Xiao; PANG, Qing-Jiang; YANG, Chang-Chun

    2014-01-01

    Objective : To summarize the functional outcome of tarsometatarsal joint fracture-dislocation managed according to Myerson classification. Methods : Total eighty cases of tarsometatarsal joint fracture-dislocation were treated from Mar 2004 to Feb 2012. According to the Myerson classification, there were 14 cases in type A, 12 cases in type B1, 28 cases in type B2, 11 cases in type C1 and 15 cases in type C2. All the cases were treated with open reduction and internal fixation and the incisions and implants were also selected according to the Myerson classification. X-ray was examined during the follow-up period and functional evaluation was carried out by American Orthopaedic Foot and Ankle Society (AOFAS) midfoot score system. Analysis of variance was used to test the different types of Myerson classification. Results : Sixty eight patients got a mean follow-up of 24 months (15-36 months). No patient suffered from infection, skin flap necrosis and X-ray showed there were no implants loosening or breakage. The mean AOFAS score was 88.4(47-100) and excellent and good result was 89.7%. The differences among Myerson classifications showed that there were statistical significance between type B and type A, type C (P<0.05) Three patients suffered from severe pain and difficult walking, X-ray showed the ambiguity of the joint space, which can be diagnosed as posttraumatic arthritis. One patient had arthrodesis finally. Conclusion : The Myerson classification is helpful to make preoperative plan and judging prognosis to the tarsometatarsal joint injuries. In type B, single or double incisions with screw or plate fixation is enough, while in type A and type C, double or triple incisions with screw or plate fixation in medial joints and Kirschner wire fixation in lateral joints are needed. Postoperatively, the type B patients had better prognosis than type A and type C patients. However, the concomitant injuries around the tarsometatarsal joint were not included in Myerson

  20. Suspension Arthroplasty for Old Fracture-Dislocations of the Fifth Carpometacarpal Joint.

    PubMed

    Kato, Naoki; Fukumoto, Keizo

    2016-06-01

    It is well known that treatment of the old fracture-dislocations of the fifth carpometacarpal (CMC) joint is challenging. For patients with persistent pain due to this condition, numerous surgical techniques have been proposed. Here, we present a novel surgical technique, CMC joint suspension arthroplasty, using a partial slip of the extensor carpi ulnaris tendon. This procedure follows principles similar to the procedure of trapeziectomy with suspension arthroplasty for treatment of thumb CMC joint arthritis. We believe this suspension arthroplasty has several advantages compared with other surgical procedures. First, mobility of the fifth metacarpal is greatly preserved because the fifth metacarpal is stabilized only by the ligament against the fourth metacarpal. Second, the length of the fifth ray can be maintained by adjusting the level of the drill hole of the fourth metacarpal. Third, malrotation of the little finger can be prevented by drilling the holes of the fifth and fourth metacarpals in the proper direction. We believe this surgical technique could be a better treatment option for degenerative arthrosis of the fifth CMC joint. PMID:27077466

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

    PubMed

    Nikolaidis, Vasilios

    2011-03-01

    We present a case of traumatic dislocation of the incudostapedial joint (ISJ) and a simple method for controlled application of the glue using commercial fibrin tissue adhesive. A 26-year-old female presented to our ENT clinic for hearing impairment to her left ear 2 months after a head trauma due to a motorcycle accident. The audiogram revealed a 40- to 50-dB HL conductive hearing loss with a notch configuration in bone conduction curve on the left ear. Computed tomography of the left temporal bone revealed a longitudinal fracture line. An exploratory tympanotomy was performed under general anesthesia. The ISJ was found dislocated while the incus was trapped by the edges of the bony lateral attic wall fracture. A small bony edge that impeded incus movement was removed and a small amount of the glue was precisely applied to the lenticular process of the incus with an angled incision knife. The long process of the incus was firmly pressed over the stapes for 30 seconds with a 90° hook and 60 seconds after the application of the glue the ISJ was repaired. One year after our patient achieved full airbone gap (ABG) closure (ABG, ≤10 dB HL), while she demonstrated overclosure in frequencies 2 and 4 kHz. Fibrin tissue glue allowed safe, rapid, and accurate repair of the ISJ and resulted in an anatomically normal articulation as the mass and shape of the ossicles was preserved. Moreover, our patient achieved full ABG closure. PMID:21344438

  2. Reconstruction of Lisfranc joint dislocations secondary to Charcot neuroarthropathy using a plantar plate.

    PubMed

    Garchar, Dave; DiDomenico, Lawrence A; Klaue, Kaj

    2013-01-01

    Lisfranc joint dislocation secondary to Charcot arthropathy is a debilitating condition that often leads to ulceration and infection. After conservative treatment, such as bracing and appropriate shoe wear fail, the only option might be amputation. However, we have seen good clinical outcomes from applying a plate to the plantar (tension) side of the medial midfoot. In our retrospective study, 24 consecutive patients (25 feet) from April 1999 through July 2004 underwent Charcot reconstruction for Lisfranc dislocation. Clinical and radiographic follow-up examinations were performed every 3 weeks during the postoperative course. Union was achieved in 24 (96%) of the 25 feet. The average time to ambulation was 11.68 (range 7 to 20) weeks for the 24 patients. The average follow-up period was 38.0 (range 17 to 64) months. The union and interval to ambulation rates showed that a plate applied to the plantar aspect of the medial midfoot provides a strong, sturdy construct for arthrodesis and ambulation. PMID:23621976

  3. Comparison of different approaches to the reduction of anterior temporomandibular joint dislocation: a randomized clinical trial.

    PubMed

    Ardehali, M M; Tari, N; Bastaninejad, Sh; Amirizad, E

    2016-08-01

    This randomized clinical trial was designed to compare three different reduction methods for anterior temporomandibular joint (TMJ) dislocation. The three methods evaluated were the conventional method, wrist pivot method, and extraoral method. The study sample comprised 90 consecutive patients suffering from anterior dislocation of the TMJ, who were allocated randomly to one of the three groups. This study found success rates of 86.7% for the conventional method, 96.7% for the wrist pivot method, and 66.7% for the extraoral method. The extraoral method was more difficult for the physician and the patient than the other two methods. For the patients, the wrist pivot method was easier than the other methods. For the doctors, the extraoral method was significantly more difficult than the other methods. In conclusion, due to the absence of a biting risk with the extraoral method and the lack of a significant difference in success between this method and the conventional method, the extraoral method could be considered the appropriate first-line treatment where there is a risk of the patient biting the surgeon's hand. Given the overall benefits of the wrist pivot method, this method could be considered the first-line and gold standard treatment modality in other cases. PMID:27160610

  4. Newly developed anatomical and functional ligament reconstruction for the Lisfranc joint fracture dislocations: a case report.

    PubMed

    Hirano, Takaaki; Niki, Hisateru; Beppu, Moroe

    2014-09-01

    A 15-year-old male complained of pain in the left foot that occurred when changing direction while running and at presentation, he had difficulty in walking due to pain and swelling. Plain X-ray of the foot revealed a Myerson Type B2 Lisfranc fracture dislocation, and 3-D computed tomography (CT) revealed proximal fractures of the 2nd-4th metatarsals. The Lisfranc ligament was anatomically reconstructed using a graft of the gracilis tendon. During aftercare, partial weight bearing was permitted at 6 weeks postoperatively and full weight bearing at 8 weeks postoperatively. The patient resumed sporting activities 3 months postoperatively. A plain X-ray taken 12 months postoperatively showed favorable joint congruency, and the patient scored 100 points on the Japanese Society for Surgery of the Foot standard rating system midfoot scale. Our anatomical ligament reconstruction is a useful new method of anatomical reduction and maintenance, and it shortens the duration of aftercare. PMID:25103712

  5. Lateral dislocation of the knee joint after total knee arthroplasty: a case report

    PubMed Central

    Ugutmen, Ender; Ozkan, Korhan; Unay, Koray; Mahirogullari, Mahir; Eceviz, Engin; Taser, Omer

    2008-01-01

    Background Total knee arthroplasty (TKA) is a successful therapy for functional improvement and pain relief in advanced symptomatic degeneration of the knee joint. But it can be associated with many complications, one of which is instability. Case presentation A 70-year-old woman was referred to our hospital because of right knee dislocation after TKA was performed on her right knee due to severe varus deformity and flexion contracture. This instability was caused by persistent MCL tightness and iatrogenic lateral collateral, arcuate ligament, and popliteus tendon injury. The torn lateral collateral ligament and arcuate ligament were sutured with no. 2 non-absorbable (Ethibond) sutures with plication of the posterolateral knee capsule. A deep-dish liner was inserted to optimize soft tissue tension. Conclusion This is a very severe complication, and surgeons must be cautious about ligament balancing and soft tissue resection during TKA for severe varus and valgus deformities. PMID:18687153

  6. A novel multiple joint dislocation syndrome associated with a homozygous nonsense variant in the EXOC6B gene.

    PubMed

    Girisha, Katta Mohan; Kortüm, Fanny; Shah, Hitesh; Alawi, Malik; Dalal, Ashwin; Bhavani, Gandham SriLakshmi; Kutsche, Kerstin

    2016-08-01

    We report two brothers from a consanguineous couple with spondyloepimetaphyseal dysplasia (SEMD), multiple joint dislocations at birth, severe joint laxity, scoliosis, gracile metacarpals and metatarsals, delayed bone age and poorly ossified carpal and tarsal bones, probably representing a yet uncharacterized SEMD with laxity and dislocations. This condition has clinical overlap with autosomal dominantly inherited SEMD with joint laxity, leptodactylic type caused by recurrent missense variants in the kinesin family member 22 gene (KIF22). Single-nucleotide polymorphism array analysis and whole-exome sequencing in the two affected siblings revealed a shared homozygous nonsense variant [c.906T>A/p.(Tyr302*)] in EXOC6B as the most likely cause. EXOC6B encodes a component of the exocyst complex required for tethering secretory vesicles to the plasma membrane. As transport of vesicles from the golgi apparatus to the plasma membrane occurs through kinesin motor proteins along microtubule tracks, the function of EXOC6B is linked to KIF22 suggesting a common pathogenic mechanism in skeletal dysplasias with joint laxity and dislocations. PMID:26669664

  7. 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. PMID:26558677

  8. Irreducible palmar metacarpophalangeal joint dislocation due to junctura tendinum interposition: a case report and review of the literature.

    PubMed

    Patel, M R; Bassini, L

    2000-01-01

    Three different anatomic structures have been reported to prevent reduction of a palmar dislocation of metacarpophalangeal joint: dorsal capsule, palmar plate, and a ruptured collateral ligament. In our case, extensor digitorum communis of the fifth finger and extensor digiti minimi subluxated on the ulnar side of the fifth metacarpal neck. Extensor digitorum communis of the fourth finger remained in its anatomic location. The junctura tendinum connecting the fourth and fifth extensor digitorum communis tendons slipped distal and then palmar to the metacarpal head, where it was trapped between the metacarpal neck and the base of the proximal phalanx. It was easily pulled out and the joint promptly reduced. Residual subluxation persisted due to rupture of the radial collateral ligament and the dorsal capsule. Repair restored joint reduction and stability. (J Hand Surg 2000; 25A:166-172. PMID:10642488

  9. Fracture of Proximal Humerus with dislocation of Glenohumeral joint in a 3 year old child: A case report

    PubMed Central

    Gupta, Rajul; Singh, Amardeep; Singh, Kunwar Kulwinder; Vohra, Rajeev

    2013-01-01

    Introduction: Though proximal humeral physeal injuries are common in children, reports of proximal humeral physeal injuries with disruption of glenohumeral joint are exceedingly rare. We here report such a case. Case Report: A three year old male patient presented to us with proximal humeral physeal separation along with glenohumeral dislocation. Under general anaesthesia, closed reduction could be achieved. Thereafter, three Kirschner wires were used to fix the physeal injury. Wires were removed at six weeks and physiotherapy was started. Good range of motion was achieved, and follow up radiographs demonstrated no evidence of growth arrest at one year. Conclusion: In spite of significant displacement in cases of proximal humeral physeal injury with glenohumeral dislocation in children, closed reduction can be achieved and should be attempted.

  10. [Volar dislocation of the second and third carpometacarpal joint three months after a fall during a soccer game].

    PubMed

    Mørup-Petersen, Anne; Ryge, Camilla; Engelund, Dorte

    2015-01-26

    Volar dislocation of the second and third carpometacarpal joint is extremely rare and most often caused by high-energy trauma. In this case a 15-year-old boy fell on his hand while playing soccer. The injury was undiagnosed for three months, perhaps due to an ipsilateral forearm fracture. He was treated with open reduction and Kirchner wire fixation for nine weeks. At two years follow-up he had a painfree hand with a 20% reduction in grip strength. PMID:25612953

  11. 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. PMID:27001782

  12. Prevention of congenital dislocation of the hip. The Swedish experience of neonatal treatment of hip joint instability.

    PubMed

    Palmén, K

    1984-01-01

    The extensive work on early diagnosis and treatment of CDH (in the broad sense of this term) in Sweden has formed the basis of our present organization of prevention of hip dislocation. Practically all children are born in hospital, at present about 93,000 per year (1980). Routine examination of the hip joints has been included in the check-ups of newborns since the beginning of the 1950's. The centralization of obstetrics, especially during the last decade, has facilitated the organization of these examinations by paediatric consultants in all obstetric departments. All cases of hip joint instability are recorded, and during the last few years the frequency has been about 12 per thousand, probably with some over-diagnosis due to registration of uncertain cases. All definite cases of hip instability have been treated immediately at the orthopaedic departments. A study of a series of untreated newborns with transient instability has shown that the majority, but not all, will develop normal hip joints without treatment. This has been one reason for the recommendation to treat all unequivocal cases of hip instability. The present organization of examination and treatment is described. Detailed and practical instructions for the examination and treatment are given. Follow-ups of children treated for hip instability in the neonatal period are reported. It has been found that in practically all these patients anatomically normal hip joints are achieved by means of correct and carefully followed up treatment. The findings in 65 patients with neonatal hip instability in whom the treatment was unsuccessful or inadequate have underlined the importance of a strict treatment schedule, experienced doctors and detailed information to the parents. The effect of diagnosis and treatment of hip instability neonatally on the frequency of late-diagnosed cases of CDH was studied by recording all late-diagnosed cases at all orthopaedic departments. It was clear from the latter study

  13. Acute spontaneous atraumatic bilateral anterior dislocation of the shoulder joint with Hill-Sachs lesions: first reported case and review of literature

    PubMed Central

    Manoharan, Gopikanthan; Singh, Rohit; Ahmed, Bessam; Kathuria, Vinod

    2014-01-01

    The anatomy of the shoulder joint comprises a relatively large humeral head with a shallow glenoid cavity allowing a remarkable range of motion at the expense of inherent instability. Despite anterior shoulder dislocations being the most common type encountered, bilateral dislocations are rare and almost always posterior. The aetiology is usually direct or indirect trauma related to sports, seizures, electric shock or electroconvulsive therapy. We present the first reported case of atraumatic bilateral acute anterior shoulder dislocations with associated Hill-Sachs lesions in a young, fit and well patient with no comorbidities. MRI illustrated the Hill-Sachs lesions with superior labral tear from anterior to posterior, and confirmed the acute nature of the injury by demonstrating the bone marrow oedema. The patient was treated surgically with arthroscopic anterior stabilisation. At 6 months following surgery, the patient has a pain free full range of movement of both shoulders with no further dislocations and has returned to work. PMID:24895390

  14. 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

    2016-01-01

    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. PMID:27163903

  15. Delayed Presentation of Metacarpophalangeal Joint Dislocation of the Thumb in Children Requiring Open Reduction: Two Cases Reported and Review ofLiterature

    PubMed Central

    Blucher, Nicola; Srinivasan, Shyamsundar; Bass, Alfie

    2015-01-01

    Introduction: Dislocation of the metacarpophalangeal joint (MCPJ) of the thumb is rare in children and delayed presentation of this injury is even more uncommon in the literature. We report two cases, both children, who presented to fracture clinic with a dislocated thumb over one week after initial injury. In each case closed reduction was attempted but failed, and open reduction was necessary. Case Report: Case Presentation 1: A 4 year-old right-hand dominant girl sustained a hyper-extension injury to her right thumb while on holiday abroad. She was told she has “sprained” her thumb. On review in fracture clinic 10 days later, the MCPJ of her thumb remained swollen and bruised. Radiographs showed a dorsally dislocated MCPJ of the right thumb. Case Presentation 2: A four-year old right-hand dominant boy presented to fracture clinic after being referred from A&E with a left ‘thumb injury’ – his thumb had accidentally been jammed in a door 1 week previously. Radiographs were reviewed and repeated, confirming a MCPJ dislocation. Conclusion: Dislocation of the MCPJ of the thumb is extremely uncommon in children and therefore the diagnosis can be easily missed. Two unusual cases of dislocated MCPJ of the thumb in children that presented late because both radiological and clinical features had been missed are described. Closed reduction should always be attempted first but it should be recognised that conversion to an open reduction may be needed, particularly if there is a delay in presentation. There are various surgical options for open reduction including volar and dorsal approaches and arthroscopic procedures. The optimal method is controversial. We have explained a successful open reduction using a dorsal approach. In both cases the volar plate was found to be interposed within the joint blocking reduction. At follow up the patients had regained a full range of movement, normal power and grip strength. PMID:27299055

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

    PubMed Central

    Carrera, Guillermo; Baynes, Keith; Mautz, Alan; DuBois, Melissa; Cerniglia, Ross; Ryan, Lawrence M.

    2016-01-01

    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. PMID:23609408

  17. [Acute acromioclavicular dislocations].

    PubMed

    Riand, N; Sadowski, C; Hoffmeyer, P

    1999-12-01

    Acromioclavicular dislocations represent over 10% of acute traumatic injuries to the shoulder girdle. The mechanism is usually a direct impact on the shoulder with the arm in adduction, producing rupture of the acromioclavicular (AC) ligaments, then of the coracoclavicular (CC) ligament, with displacement of the lateral end of the clavicle. Rockwood described 6 grades of injury. Physical examination usually provides the diagnosis, which is confirmed by radiological examination. X-rays centered on the AC joint, if necessary with forceful adduction of both shoulders or under traction, are useful to evaluate the severity of the lesion. Grade I and II lesions are usually treated conservatively by simply immobilizing the arm for 3 to 4 weeks. Surgical treatment is usually advocated for grade IV, V and VI lesions: AC or CC fixation, sometimes associated with ligament repair, depending on the surgeons. AC pinning or C-C screw fixation are the techniques most often used. Management of grade III lesions remains controversial. Some authors advocate immediate surgical treatment in young, active patients, in heavy laborers and even in slender individuals. The choice of the operative technique is controversial, as no single technique has clearly proved to be superior to others. Other authors advocate conservative treatment, which gives functional results which patients consider quite acceptable, with faster recovery; patients should be informed that results are essentially similar, whatever the treatment. The possibility of performing secondary operations with good results in cases with failure of conservative management is a further argument in favor of applying conservative therapy first in acute injuries. PMID:10675933

  18. 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

  19. Multiligamentous injuries and knee dislocations.

    PubMed

    Gimber, Lana H; Scalcione, Luke R; Rowan, Andrew; Hardy, Jolene C; Melville, David M; Taljanovic, Mihra S

    2015-11-01

    Complex capsular ligamentous structures contribute to stability of the knee joint. Simultaneous injury of two or more knee ligaments, aside from concurrent tears involving the anterior cruciate and medial collateral ligaments, is considered to be associated with femorotibial knee dislocations. Proximal tibiofibular joint dislocations are not always easily recognized and may be overlooked or missed. Patellofemoral dislocations can be transient with MR imaging sometimes required to reach the diagnosis. In this article, the authors describe the mechanism of injury, ligamentous disruptions, imaging, and treatment options of various types of knee dislocations including injuries of the femorotibial, proximal tibiofibular, and patellofemoral joints. PMID:26002747

  20. [Dislocation of the clavicle: case report].

    PubMed

    Paša, L; Kalandra, S

    2011-01-01

    A traumatic dislocation of the clavicle is a rare injury. So far 37 reports of this trauma have been found in the relevant literature; they are most often treated by surgery. A 32-year-old woman was admitted to local hospital for polytraumata sustained in a motor car accident. Once the patient had been stabilised, at three months after injury, stabilisation of the left dislocated clavicle was undertaken. The medial end was stabilised, using a strip dissected from the ligament of the sternoclavicular (SC) joint capsule, with Orthocord sutures, and laterally by coracoacromial ligament transfer (Weaver and Dunn technique) and K-wire fixation through the acromioclavicular (AC) articulation. The K-wire was removed 10 weeks after stabilisation. At 6 months after the repair surgery, the patient was free of any complaint, with no motion restriction and with good configuration of the SC and AC joints. The mean scores according to the University of California at Los Angeles (UCLA) rating system were 14 points before surgery and 28 points at 6 months after surgery; the mean Constant scores were 56 and 92 at the respective intervals. The clinical outcome of surgical stabilisation in this patient was very good. She had no signs of instability and no restriction of motion at the joints treated. PMID:21575562

  1. TREATMENT OF PARALYTIC HIP DISLOCATION AMONG SPASTIC QUADRIPLEGIC CEREBRAL PALSY PATIENTS BY MEANS OF FEMORAL AND PELVIC OSTEOTOMY, WITHOUT OPENING THE JOINT CAPSULE (CAPSULOPLASTY)

    PubMed Central

    Junior, Fernando Farcetta; Abreu, Fabio Peluzo; Neves, Daniella Lins; Kertzman, Paulo Facciola; Zuccon, Alexandre; De Oliveira Bittencourt, Simone; Lopes, Davi Moshe Leopold

    2015-01-01

    Objectives: To show the preoperative planning and results from surgical treatment for paralytic hip dislocation among patients with cerebral palsy. The techniques used were proximal femoral varus derotation osteotomy in association with Dega iliac osteotomy, without opening the joint capsule. Methods: We performed a retrospective review of ten hips in eight patients with spastic quadriplegic cerebral palsy who underwent surgical treatment between 2003 and 2005, with the same surgical technique. The pre and postoperative clinical and radiological parameters, and the preoperative planning using an image intensifier, were assessed. The clinical parameters analyzed were: pain, hygiene-related difficulties and positioning difficulties. The radiological parameters were Reimer's index, the acetabular index and the neck-shaft angle. These results were subjected to statistical analysis. Results: We obtained good results with this technique. After a mean follow-up of three years, all the hips were observed to be stable at the last assessment, and there was a high degree of satisfaction among the families in relation to the treatment. We also showed that preoperative planning using an image intensifier allowed us to reduce and stabilize these hips without the need for capsuloplasty. Conclusion: The authors conclude that in treating hip dislocation among spastic quadriplegic cerebral palsy patients, capsuloplasty is unnecessary for stabilizing the coxofemoral joint. PMID:27022539

  2. Acute spontaneous atraumatic bilateral anterior dislocation of the shoulder joint with Hill-Sach’s lesions: A rare case

    PubMed Central

    Sachit, Malhan; Shekhar, Agarwal; Shekhar, Srivastav; joban, Singh Har

    2015-01-01

    Introduction: Late diagnoses of orthopedic injuries after epileptic crisis are a matter of concern. The rarity of correlation between seizure and specific trauma incidences such as bilateral anterior shoulder dislocation, may lead to improper estimation of the patient’s clinical state, wrong treatment and unpleasant complications. Case Report: We report a rare case of bilateral anterior shoulder dislocation associated with coracoid processes fracture after a seizure episode, in a young lady of 29 years. This is a rare event, however as patient is often disoriented after seizures, frequently this can be missed diagnosis. So this article puts emphasis on possibilities of rare diagnosis, which if treated promptly can lead to early restoration of complete movement. Conclusion: Although it is not a common problem, but one should have a high degree of suspicion and should always opt for further radiological examination if there is any doubt. PMID:27299022

  3. Bilateral posterior sternoclavicular dislocation.

    PubMed

    Baumann, Matthias; Vogel, Tobias; Weise, Kuno; Muratore, Tim; Trobisch, Per

    2010-07-01

    Posterior sternoclavicular dislocations are a rare injury, representing <5% of all sternoclavicular dislocations and 1 in 1600 shoulder girdle injuries. Proper imaging with computed tomography and prompt diagnosis are essential steps in preventing potentially lethal complications observed in approximately 3% of all posterior sternoclavicular dislocations. Surgical treatment is necessary if closed reduction fails. With the medial clavicular epiphysis being the last to close (between ages 22 and 25), children and adolescents typically present with epiphyseal fractures rather than joint dislocations. If closed reduction fails, open reduction and internal fixation (ORIF) should be considered in fractures, whereas complex reconstructions with tendon graft procedures have been recommended for joint dislocations. This article presents a case of a traumatic bilateral posterior sternoclavicular dislocation due to an epiphyseal fracture in a 15-year-old boy. To our knowledge, this is the first reported case of a bilateral posterior sternoclavicular dislocation. Attempted closed reduction failed with redislocation after 2 days. The patient subsequently required ORIF. This article describes our technique with anterior retraction of the medial clavicle, closure of the posterior periosteum, and ORIF using nonabsorbable sutures. Postoperative shoulder mobilization was started on day 1. At final follow-up, the patient was completely asymptomatic. PMID:20608625

  4. A rigid body model for the assessment of glenohumeral joint mechanics: Influence of osseous defects on range of motion and dislocation.

    PubMed

    Welsh, Mark F; Willing, Ryan T; Giles, Joshua W; Athwal, George S; Johnson, James A

    2016-02-29

    The purpose of this study was to employ subject-specific computer models to evaluate the interaction of glenohumeral range-of-motion and Hill-Sachs humeral head bone defect size on engagement and shoulder dislocation. We hypothesized that the rate of engagement would increase as defect size increased, and that greater shoulder ROM would engage smaller defects. Three dimensional computer models of 12 shoulders were created. For each shoulder, additional models were created with simulated Hill-Sachs defects of varying severities (XS=15%, S=22.5%, M=30%, L=37.5%, XL=45% and XXL=52.5% of the humeral head diameter, respectively). Rotational motion simulations without translation were conducted. The simulations ended if the defect engaged the anterior glenoid rim with resultant dislocation. The results showed that the rate of engagement was significantly different between defect sizes (0.001joint translation may be occurring, causing these defects to engage. Therefore, further studies on clinical pre-operative joint laxity and ROM may enable the prediction of engagement. PMID:26862040

  5. Comparison of surgical outcomes between fixation with hook plate and loop suspensory fixation for acute unstable acromioclavicular joint dislocation: a systematic review and meta-analysis.

    PubMed

    Arirachakaran, Alisara; Boonard, Manusak; Piyapittayanun, Peerapong; Phiphobmongkol, Vajarin; Chaijenkij, Kornkit; Kongtharvonskul, Jatupon

    2016-08-01

    Treatment of acute (≤4 weeks) high-grade acromioclavicular (AC) joint separation (types III-VI) is still controversial. Currently, the two modern techniques that are widely used include hook plate fixation and coracoclavicular (CC) ligament fixation using a suspensory loop device (tightrope, synthetic ligament or absorbable polydioxansulfate sling). These techniques are both reported to have superior clinical outcomes. This systematic review and meta-analysis aimed to assess and compare clinical outcomes of hook plate fixation versus fixation of the CC ligament using a loop suspensory fixation (LSF) device for the treatment of AC joint injury. These clinical outcomes consist of the Constant-Murley score (CMS), pain visual analog score (VAS) and postoperative complications. Relevant comparative studies were identified from MEDLINE and Scopus from inception to October 5, 2015. Five of 571 studies were eligible; 5, 3, 3, and 5 studies were included in the pooling of CMS, pain VAS, surgical time and postoperative complications, respectively. The unstandardized mean difference (UMD) of the CMS for LSF was 4.43 [95 % confidence interval (CI) 0.73, 8.14], which was statistically significantly higher than the CMS in hook plate fixation. For VAS, the UMD was 0.02 points (95 % CI -3.54, 3.73) higher than LSF but without statistical significance. The surgical time of LSF was 16.21 min (95 % CI 6.27, 26.15) statistically significantly higher than hook plate fixation. LSF had a lower chance of postoperative complications by 0.62 units (95 % CI 0.30, 1.32) when compared to hook plate fixation, but this also was not statistically significant. In acute high-grade AC joint injuries, loop suspensory fixation had higher postoperative functional CMS and mean surgical time when compared to hook plate fixation. However, for postoperative VAS and complication rates, there were no statistically significant differences between groups. PMID:27334621

  6. Results of Arthroscopy-Assisted TightRope Repair of Acromioclavicular Dislocations

    PubMed Central

    Flinkkilä, Tapio E.; Ihanainen, Essi

    2013-01-01

    Background The present study assessed results of arthroscopy-assisted TightRope (Arthrex, Naples, FL, USA) repair of acute Rockwood grade III and V acromioclavicular (AC) dislocations. Methods We retrospectively reviewed the medical records of 57 patients with AC dislocations treated with TightRope fixation: 15 Rockwood grade III and 42 grade V. Functional results were assessed using the Constant score, and Disabilities of Arm, Shoulder and Hand (DASH) and RAND 36-ltem Health Survey scores after a mean 2.6 years of follow-up (range 1.0 years to 4.5 years). Radiographic results were assessed using the AC joint coracoclavicular (CC) distance. Results Postoperative radiographs showed anatomical AC joint reduction in all patients. In nine patients, fixation failed before 6 weeks postoperatively, mainly as a result of suture breakage. For the remaining 47 patients, CC distance was well maintained at 6 weeks. At follow-up, mean (SD) CC distance was significantly increased compared to the contralateral side or postoperative radiographs [17 (4) mm versus 10 (3) mm]. Mean DASH score was 9, Constant score was 88 and the RAND 36 score showed a quality of life similar to the Finnish reference population. Conclusions Despite initial good reduction of grade III and V AC dislocations using TightRope fixation, subluxation often recurs after 6 weeks. Patients suffer minor subjective complaints that do not worsen the quality of life.

  7. 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 ...

  8. Subtalar dislocation

    SciTech Connect

    El-Khoury, G.Y.; Yousefzadeh, D.K.; Mulligan, G.M.; Moore, T.E.

    1982-05-01

    Over a period of three years we have seen nine patients with subtalar dislocation, all of whom sustained violent trauma to the region of the ankle and hind foot. All but one patient were males. Clinically a subtalar dislocation resembles a complicated fracture dislocation of the ankle but a definitive diagnosis can only be made radiographically. The mechanism of injury and radiographic features of this injury are discussed.

  9. Clinical and radiological results after coracoclavicular ligament reconstruction for type III acromioclavicular joint dislocation using three different techniques. A retrospective study

    PubMed Central

    VASCELLARI, ALBERTO; SCHIAVETTI, STEFANO; BATTISTELLA, GIUSEPPE; REBUZZI, ENRICO; COLETTI, NICOLÒ

    2015-01-01

    Purpose the purpose of this retrospective study was to present the outcomes of three different techniques for the treatment of type III acromioclavicular joint dislocations: arthroscopic TightRope (TR), arthroscopic GraftRope (GR), and open reconstruction of the coracoclavicular (CC) ligament using the Ligament Augmentation and Reconstruction System (LARS). Methods eighteen patients underwent clinical and radiological evaluations after a mean follow-up time of 43 months. The following clinical outcome measures were considered: the Disability of the Arm, Shoulder and Hand outcome measure (DASH), the Nottingham Clavicle Score (NCS), and the Constant score (CS). On X-rays, the CC distance was measured. Results the median DASH score at follow-up was 12.5 in the TR group, 5 in the GR group, and 4.2 in the LARS group. The median NCS value was 88 in the TR group, 88 in the GR group, and 91 in the LARS group. The median CS was 100 in the TR group, 95 in the GR group, and 94.5 in the LARS group. The mean CC distance was 10.3 mm in the TR group, 13.8 in the GR group, and 16.6 in the LARS group. Conclusions all three techniques proved to be reliable in providing good clinical outcomes, although none of the studied techniques demonstrated reliability in maintaining anatomical reduction after surgery. Level of evidence Level III, retrospective comparative study. PMID:26605251

  10. Hypermobile joints

    MedlinePlus

    ... too far. In children with hypermobility syndrome, those ligaments are loose or weak. This may lead to: Arthritis, which may develop over time Dislocated joints, which is a separation of two bones where they meet at a joint Sprains and strains Children with hypermobile joints also often have flat ...

  11. Bipolar dislocation of the clavicle.

    PubMed

    Jiang, Wei; Gao, Shu-Guang; Li, Yu-Sheng; Lei, Guang-Hua

    2012-11-01

    Bipolar dislocation of the clavicle at acromioclavicular and sternoclavicular joint is an uncommon traumatic injury. The conservative treatments adopted in the past is associated with redislocation dysfunction and deformity. A 41 years old lady with bipolar dislocation of right shoulder is treated surgically by open reduction and internal fixation by oblique T-plate at sternoclavicular joint and Kirschner wire stabilization at acromioclavicular joint. The patient showed satisfactory recovery with full range of motion of the right shoulder and normal muscular strength. The case reported in view of rarity and at 2 years followup. PMID:23325981

  12. Economic Dislocation and Worker Adjustment Assistance Act. Joint Hearings on S. 538 to Implement the Recommendations of the Secretary of Labor's Task Force on Economic Adjustment and Worker Dislocation, and for Other Purposes, before the Subcommittee on Labor and the Subcommittee on Employment and Productivity of the Committee on Labor and Human Resources. United States Senate, One-Hundredth Congress, First Session (March 10 and 26, 1987).

    ERIC Educational Resources Information Center

    Congress of the U.S., Washington, DC. Senate Committee on Labor and Human Resources.

    This congressional report on Senate Bill 538 contains the testimony that was given at joint hearings to debate the passage of the Economic Dislocation and Worker Adjustment Assistance Act. This act, which is based primarily on the recommendations of U.S. Secretary of Labor Brock's blue ribbon task force: (1) creates displaced worker units at the…

  13. 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

  14. [Arthroscopically assisted techniques for treatment of acute and chronic acromioclavicular joint injuries].

    PubMed

    Braun, S; Imhoff, A B; Martetschläger, F

    2015-05-01

    Acute and chronic acromioclavicular (AC) joint dislocation is frequently encountered in the routine clinical practice. This injury can lead to significant impairment of shoulder girdle function. Therapy based on the severity of injury is recommended to re-establish correct shoulder function. The static radiographic Rockwood classification is used to define the degree of dislocation but the clinical aspects and functional x-ray imaging of horizontal AC joint instability should also be considered for selection of the appropriate procedure. Rockwood grades I and II injuries are treated non-operatively with early functional exercise. The approach for Rockwood grade III injuries should be individual and patient-specific, with non-surgical procedures for low functional requirement patients with a high risk for surgical interventions. For patients with high demands on shoulder function surgery is recommended. A detailed diagnostic assessment frequently reveals Rockwood grade III injuries to be type IV injuries. Rockwood types IV and V AC joint dislocations require surgery for sustained stability. Treatment of acute injuries is recommended within 1-3 weeks after trauma but there is no clear evidence of a cut-off for the presence of chronic injuries. Various surgical techniques have been described in the literature. This article presents an arthroscopically assisted technique that addresses both vertical and horizontal instability of the AC joint. PMID:25964020

  15. A Bilateral Traumatic Hip Obturator Dislocation

    PubMed Central

    Karaarslan, Ahmet Adnan; Acar, Nihat; Karci, Tolga; Sesli, Erhan

    2016-01-01

    A case of a bilateral simultaneous traumatic obturator dislocation of both hip joints in an 18-year-old young man following a traffic accident is presented. We reduced the dislocated femoral heads immediately under general anesthesia followed by passive and active exercises and early full-weight bearing mobilization. After 5 years, the result was excellent. PMID:26977327

  16. Beware the Emergency Ankle Fracture Referral: An Unusual Case of Lateral Subtalar Joint Dislocation Secondary to Calcaneal Fracture with associated Lateral Malleolus Fracture

    PubMed Central

    Colegate-Stone, TJ; James, SE; Koka, SR

    2015-01-01

    Introduction: The referral of a lateral malleolus fracture is one of the commonest orthopaedic trauma presentations. Failure to fully assess the patient and radiography can lead to missing associated injuries in the hindfoot. Case Report: We describe an unusual hindfoot injury with an atypical combination of lateral subtalar dislocation and calcaneal fracture with associated lateral malleolus fracture that was initially not appreciated by the referring emergency department. This case is of particular interest as subtalar dislocation is a rare injury and lateral subtalar dislocation is even rarer. Conclusion: Failure to fully assess such injuries and manage non-operatively leads to early degenerative tibia-talar, hindfoot and midfoot changes and a difficult situation for the surgeon to salvage. We advocate early CT scan and open reduction with fixation for such cases. PMID:27299009

  17. 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.

  18. Traumatic proximal tibiofibular dislocation with neurovascular injury

    PubMed Central

    Veerappa, Lokesh A; Gopalakrishna, Chetan

    2012-01-01

    23 years old male presented with inferolateral dislocation of proximal tibiofibular joint associated with popliteal artery and common peroneal nerve injury. The extension of the injury to involve the interosseus membrane up to the distal tibiofibular joint. The association of popliteal artery injury is not reported before to the best of our knowledge. PMID:23162155

  19. 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

  20. [Traumatic hip dislocation in childhood].

    PubMed

    Stachel, P; Hofmann-v Kap-herr, S; Schild, H

    1989-06-01

    The article reports on eight cases of traumatic dislocation of the hip in children. Six of these were genuine dislocations and two dislocation fractures. The children were between 5 and 13 years of age at the time of injury. Seven of these 8 children could be followed up one to 21 years after the accident. All 7 children were free from complaints at the time of follow-up examination; in one case only we found a moderate loss of function in the injured hip joint. In this patient the x-ray film showed deformation of the head of the femur after partial necrosis of the femoral head, as well as initial signs of coxarthrosis. Prognosis of this rare injury in children is favourable if repositioning is performed in time and if relief of the hip is effected for the proper period of time, depending on the individual case. PMID:2665382

  1. Isolated Proximal Tibiofibular Dislocation during Soccer

    PubMed Central

    Chiu, Casey; Sheele, Johnathan Michael

    2015-01-01

    Proximal tibiofibular dislocations are rarely encountered in the Emergency Department (ED). We present a case involving a man presenting to the ED with left knee pain after making a sharp left turn on the soccer field. His physical exam was only remarkable for tenderness over the lateral fibular head. His X-rays showed subtle abnormalities of the tibiofibular joint. The dislocation was reduced and the patient was discharged from the ED with orthopedic follow-up. PMID:26713164

  2. Bilateral anterior chamber intraocular lenses dislocation in a patient with habitual eye rubbing.

    PubMed

    Poh, E P; Fariza, N Nor; Mariam, I

    2005-08-01

    A 61-year-old Chinese man presented with bilateral posteriorly dislocated anterior chamber intraocular lenses (AC IOLs) one year after successful vitrectomy, removal of bilateral dislocated mature cataractous lenses and AC IOLs implantation. A thorough clinical evaluation revealed habitual eye rubbing as the only possible cause. PMID:16379196

  3. [Sonographic measures of the hip joint of 1328 newborns of Han and Uygur nationalities-relative factors of congenital dislocation of hip].

    PubMed

    Yang, J; Chen, L; Tian, B

    1997-08-01

    The four sonographic methods (Engesaeter, Terjesen, Graf, Morin-Harcke) were used for examining the hip joint of 1328 newborns of Han and Uygur nationalities. The difference between Han and Uygur newborns was not statistical significant, but some literatures reported that in our country, the incidence of different nationalities in different regions varied. Our conclusion is that there is no obvious relationship between the depth of the acetabulum and the percentage of the femoral head covered by the acetabulum. It is caused by other factors, inherent or acquired. The value of the hip joint of the male and female has significant difference (P < 0.0005). The incidence of CDH in girls is much higher than that in boys. This may be related to the different depth of the acetabulum and different percentage of the femoral head covered by the acetabulum. In the period of newborn, girl's depth of the acetabulum is smaller than that of boys. PMID:10678065

  4. 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.

  5. 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.

  6. 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. PMID:11265904

  7. Dislocated shoulder - aftercare

    MedlinePlus

    Shoulder dislocation - aftercare; Shoulder subluxation - aftercare; Shoulder reduction - aftercare ... You most likely dislocated your shoulder from a sports injury or accident, such as a fall. You have likely injured (stretched or torn) some of the muscles, ...

  8. Dislocated shoulder - aftercare

    MedlinePlus

    Shoulder dislocation - aftercare; Shoulder subluxation - aftercare; Shoulder reduction - aftercare ... Horn AE, Ufberg JW. Management of common dislocations. In: ... Extremity 6th ed. Philadelphia, PA: ElsevierMosby; 2011:chap 92.

  9. 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

  10. Joint-sparing Corrections in Malunited Lisfranc Joint Injuries.

    PubMed

    Nery, Caio; Raduan, Fernando; Baumfeld, Daniel

    2016-03-01

    Lisfranc fracture-dislocations are very serious and potentially disabling injuries. Unfortunately, they are often misdiagnosed. Multiplanar midfoot deformities that result from these fracture-dislocations are precursors of joint degeneration and significant functional disabilities. Anatomic reduction with different types of internal fixation is an efficient method to reconstruct midfoot alignment and stability. Joint-preserving reconstruction techniques emerge as a viable alternative to corrective fusion as they achieve stable joint realignment with preserved motion. PMID:26915786

  11. [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. PMID:23177945

  12. [Hip dislocation. Organization of screening and follow-up].

    PubMed

    Abuamara, S; Dacher, J N; Gaucher, S; Lechevallier, J; Brossard, V; Delhaye, L; Durand, C; Levasseur, F; Henocq, A

    1999-06-01

    Early detection and low-risk treatment are the two main objectives of the management of developmental dislocation of the hip. The best way to evaluate neonatal hips is to perform clinical and ultrasound examinations at the same time, and to confront their results. Early diagnosis allows to restrict treatment to infants with neonatal dislocation who do not improve by 4 weeks of age. On the other hand, neonates with reductible dislocated hips must be treated at birth and followed at the joint consultation. Early diagnosis and management must not decrease later efforts to detect dislocated hip until walking age. PMID:10394462

  13. An Unusual Variant of Pipkin's Fracture Dislocation of Hip: A Case Report

    PubMed Central

    Jangir, Rajat; Mishra, Diwakar

    2014-01-01

    Introduction: Injuries of the hip joint from pure hip dislocations to fracture dislocations have been described and classified by various authors. These descriptions do not include fracture dislocation of hip associated with fracture of the greater trochanter. Case Report: We report an unusual case of fracture dislocation of hip in which posterior dislocation of hip was associated with fracture of acetabulum, femoral head, femoral neck, greater trochanter and ipsilateral shaft of tibia. The fracture dislocation was managed with open reduction and internal fixation. Such fracture dislocation has not been reported in literature to the best of our knowledge. Conclusion: We believe that fracture dislocations associate with fractures of greater trochanter should be included in current classification systems of fracture dislocations of hip. PMID:27298974

  14. Autologous blood injection for the treatment of recurrent mandibular dislocation.

    PubMed

    Coser, R; da Silveira, H; Medeiros, P; Ritto, F G

    2015-08-01

    The purpose of the present study was to evaluate the effectiveness of autologous blood injection in the treatment of recurrent temporomandibular joint dislocation. Eleven patients diagnosed with recurrent dislocation of the joint that could not be self-reduced, received bilateral injections of autologous blood in the superior joint compartment and pericapsular region. During a follow-up period ranging from 24 to 35 months (average 29.6 months), eight patients (72.7%) did not show new episodes of dislocation. The most advocated treatment for recurrent dislocation is eminectomy, which involves a skin incision, with the risk of damaging the facial nerve, requires general anaesthesia, and presents an average success rate of 85% according to the literature. Autologous blood injection is a simple, rapid, minimally invasive, and cost-effective technique, with a low possibility of complications, and is a feasible alternative treatment before surgical intervention. PMID:26022511

  15. 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°. PMID:27499325

  16. Dislocation Formation in Alloys

    NASA Astrophysics Data System (ADS)

    Minami, Akihiko; Onuki, Akira

    2006-05-01

    An interaction between dislocations and phase transitions is studied by a phase field model both in two and three dimensional systems. Our theory is a simple extension of the traditional linear elastic theory, and the elastic energy is a periodic function of local strains which is reflecting the periodicity of crystals. We find that the dislocations are spontaneously formed by quenching. Dislocations are formed from the interface of binary alloys, and slips are preferentially gliding into the soft metals. In three dimensional systems, formation of dislocations under applied strain is studied in two phase state. We find that the dislocation loops are created from the surface of hard metals. We also studied the phase separation above the coexisting temperature which is called as the Cottrell atmosphere. Clouds of metals cannot catch up with the motion of dislocations at highly strained state.

  17. 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

  18. Imaging screw dislocations at atomic resolution by aberration-corrected electron optical sectioning

    NASA Astrophysics Data System (ADS)

    Yang, H.; Lozano, J. G.; Pennycook, T. J.; Jones, L.; Hirsch, P. B.; Nellist, P. D.

    2015-06-01

    Screw dislocations play an important role in materials' mechanical, electrical and optical properties. However, imaging the atomic displacements in screw dislocations remains challenging. Although advanced electron microscopy techniques have allowed atomic-scale characterization of edge dislocations from the conventional end-on view, for screw dislocations, the atoms are predominantly displaced parallel to the dislocation line, and therefore the screw displacements are parallel to the electron beam and become invisible when viewed end-on. Here we show that screw displacements can be imaged directly with the dislocation lying in a plane transverse to the electron beam by optical sectioning using annular dark field imaging in a scanning transmission electron microscope. Applying this technique to a mixed [a+c] dislocation in GaN allows direct imaging of a screw dissociation with a 1.65-nm dissociation distance, thereby demonstrating a new method for characterizing dislocation core structures.

  19. Do normal hips dislocate?

    PubMed

    Alshameeri, Zeiad; Rehm, Andreas

    2014-11-01

    There have been a small number of case reports describing late normal-hip dislocations in children who were later diagnosed with developmental dysplasia of the hip. Here, we contest the assumption that normal hips can dislocate. We argue that (as in our case) the ultrasound scans in all published case reports on late dislocated normal hips did not show results that were entirely normal and therefore, so far, there has been no convincing evidence of a dislocation of a normal hip. We also want to highlight the importance of meticulous ultrasound and clinical assessments of high-risk children by an experienced orthopaedic surgeon. PMID:25144883

  20. Operative Treatment of Bipolar Clavicular Dislocation: A Case Report

    PubMed Central

    Schuh, Alexander; Thonse, Chirag Narayana; Schmickal, Thomas; Kleine, Ludwig

    2012-01-01

    Introduction: Simultaneous bipolar dislocation of the clavicle is uncommon and unusual, although it has been documented as panclavicular dislocation, floating clavicle, and complete dislocation of the clavicle. A review of the recent literature indicated that most bipolar clavicular dislocations have been treated non-operatively. Case Report: We report the case of a 23 year polytrauma patient with bipolar dislocation of the right clavicle. Patient presented to us 2 weeks post injury and had an unstable corao-clavicular joint. On radiographic assessment a simultaneous dislocation of the coraco-clavicular and sterno-clavicular joints of right side was diagnosed. In view of the unstable condition of the right clavicle, young age of the patient, requirement of high physical activity a decision for operative treatment for clavicle dislocation was taken. Patient was treated surgically with open reduction and tension band wiring with good result. Conclusion: Although bipolar dislocation of the clavicle are rare a high index of suspicion will avoid missed diagnosis. Open reduction and internal fixation is a good option in young patients and gives good short term result.

  1. 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.

  2. Dislocation in Spoken French.

    ERIC Educational Resources Information Center

    Calve, Pierre

    1985-01-01

    Discusses dislocation, a construction in which one element, usually a noun, is isolated either at the beginning or at the end of a sentence while being represented in the body of the sentence by a pronoun. Discusses the place of dislocation in linguistic studies and its pedagogical implications. (SED)

  3. Dislocations in yttrium orthovanadate

    NASA Astrophysics Data System (ADS)

    Eakins, D. E.; LeBret, J. B.; Norton, M. G.; Bahr, D. F.

    2004-06-01

    Dislocation structures in single crystals of yttrium orthovanadate have been identified by transmission electron microscopy. Electron diffraction was used to predict possible Burgers vectors for the dislocations. Results suggest vectors of the type {1}/{2}[1 1 1] or {1}/{4}[0 2 1] . Arguments for the likelihood of each possible vector have been presented.

  4. Parallel Dislocation Simulator

    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.

  5. 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.

  6. Electronic properties of dislocations

    NASA Astrophysics Data System (ADS)

    Reiche, M.; Kittler, M.; Uebensee, H.; Pippel, E.; Haehnel, A.; Birner, S.

    2016-04-01

    Dislocations exhibit a number of exceptional electronic properties resulting in a significant increase in the drain current of MOSFETs if defined numbers of these defects are placed in the channel. Measurements on individual dislocations in Si refer to a supermetallic conductivity. A model of the electronic structure of dislocations is proposed based on experimental measurements and tight-binding simulations. It is shown that the high strain level on the dislocation core—exceeding 10 % or more—causes locally dramatic changes in the band structure and results in the formation of a quantum well along the dislocation line. This explains experimental findings (two-dimensional electron gas, single-electron transitions). The energy quantization within the quantum well is most important for supermetallic conductivity.

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

    PubMed Central

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

    2016-01-01

    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. PMID:27583119

  8. 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. PMID:27583119

  9. Irreducible Fifth Metatarsophalangeal Joint after Car Crush Injury

    PubMed Central

    Turkmensoy, Fatih; Erinc, Samet; Ergin, Omer Naci; Ozkan, Korhan; Kemah, Bahattin

    2015-01-01

    Metatarsophalangeal joint dislocations are uncommon injuries. Herein, an irreducible dislocation of fifth metatarsophalangeal joint with fractures on the second, third, and fourth metatarsal head was reported. Joint reduction could not be achieved which necessitated open reduction. Six months after surgery the patient was walking and doing his daily activities without any complaints. He had returned to his pretrauma functional level. PMID:25861501

  10. [PDS cord fixation of sternoclavicular dislocation and para-articular clavicular fractures].

    PubMed

    Friedl, W; Fritz, T

    1994-05-01

    Sternoclavicular joint dislocation and para-articular fractures of the clavicle are rare injuries. Because severe complications of dorsal dislocations have often been seen and because functional impairment has often followed ventral dislocations, we treat most patients with such injuries operatively. Internal fixation with K-wires frequently leads to severe complications. We present our operation techniques with a resorbable 2 mm polydioxanon cord. This pack up technique can be used in both dislocations and para-articular fractures with no risk of implant dislocation. PMID:8052863

  11. Tamponade following sternoclavicular dislocation surgical fixation.

    PubMed

    Bensafi, H; Laffosse, J-M; Taam, S A; Molinier, F; Chaminade, B; Puget, J

    2010-05-01

    The authors report a case of posterior sternoclavicular dislocation surgically reduced and stabilized with tenodesis, according to the Burrows technique completed by temporary wire fixation. The patient presented postoperative pericardiac tamponade appearing progressively from brachiocephalic blood vessels bleeding. Emergency drainage was surgically placed associated with removal of the material, thus curing the patient. This complication, although exceptional, formally contraindicates the use of wire fixation in surgery of the sternoclavicular joint. PMID:20488152

  12. 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

  13. Sternoclavicular dislocation: case report and surgical technique☆

    PubMed Central

    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

  14. GPU accelerated dislocation dynamics

    NASA Astrophysics Data System (ADS)

    Ferroni, Francesco; Tarleton, Edmund; Fitzgerald, Steven

    2014-09-01

    In this paper we analyze the computational bottlenecks in discrete dislocation dynamics modeling (associated with segment-segment interactions as well as the treatment of free surfaces), discuss the parallelization and optimization strategies, and demonstrate the effectiveness of Graphical Processing Unit (GPU) computation in accelerating dislocation dynamics simulations and expanding their scope. Individual algorithmic benchmark tests as well as an example large simulation of a thin film are presented.

  15. Neglected Anterior Dislocation of Shoulder: is surgery necessary? A Rare Case with review of literature

    PubMed Central

    Shah, Kunal; Ubale, Tushar; Ugrappa, Harish; Pilankar, Samir; Bhaskar, Atul; Kale, Satishchandra

    2015-01-01

    Introduction: Shoulder joint is the most frequently dislocated joint. However, it is rarely neglected and treatment is sought immediately. Delayed or neglected shoulder dislocations are difficult to manage and require extensive procedures to obtain good functional outcome. Very few cases are described in literature showing neglected shoulder dislocation with good functional range of movement. We report a case with 3 years of neglected anterior shoulder dislocation with preserved joint function. Case Report: A 40 years old gentleman presented withfracture distal end of the radius (left). On clinical examination we observed that he had anterior dislocation of his left shoulder which was confirmed on radiographic evaluation. He had history of seizures 3 years back, which may be the cause of dislocation which went unnoticed. On examination he had good range of motion without any pain. Patient could perform all routine activities with no major functional limitation. At three years after dislocation CT Scan showed neocavity formation. Conclusion: Neglected shoulder dislocation with preserved joint function without major functional limitation is a rare presentation. This condition should be kept in mind in patients with history of seizures. Proper evaluation and counseling of patients avoids extensive procedures and avoids complications of surgery. Observation can be a treatment option in patients with preserved range of movement especially involving non dominant handand having low functional demand. This report presents rare presentation of neglected shoulder dislocation highlighting its natural history and its outcome following conservative treatment. PMID:27299102

  16. Acute traumatic patellar dislocation.

    PubMed

    Duthon, V B

    2015-02-01

    Inaugural traumatic patellar dislocation is most often due to trauma sustained during physical or sports activity. Two-thirds of acute patellar dislocations occur in young active patients (less than 20 years old). Non-contact knee sprain in flexion and valgus is the leading mechanism in patellar dislocation, accounting for as many as 93% of all cases. The strong displacement of the patella tears the medial stabilizing structures, and notably the medial patellofemoral ligament (MPFL), which is almost always injured in acute patellar dislocation, most frequently at its femoral attachment. Lateral patellar glide can be assessed with the knee in extension or 20° flexion. Displacement by more than 50% of the patellar width is considered abnormal and may induce apprehension. Plain X-ray and CT are mandatory to diagnose bony risk factors for patellar dislocation, such as trochlear dysplasia or increased tibial tubercle-trochlear groove distance (TT-TG), and plan correction. MRI gives information on cartilage and capsulo-ligamentous status for treatment planning: free bodies or osteochondral fracture have to be treated surgically. If patellar dislocation occurs in an anatomically normal knee and osteochondral fracture is ruled out on MRI, non-operative treatment is usually recommended. PMID:25592052

  17. Statistical characterization of dislocation ensembles

    SciTech Connect

    El-Azab, A; Deng, J; Tang, M

    2006-05-17

    We outline a method to study the spatial and orientation statistics of dynamical dislocation systems by modeling the dislocations as a stochastic fiber process. Statistical measures have been introduced for the density, velocity, and flux of dislocations, and the connection between these measures and the dislocation state and plastic distortion rate in the crystal is explained. A dislocation dynamics simulation model has been used to extract numerical data to study the evolution of these statistical measures numerically in a body-centered cubic crystal under deformation. The orientation distribution of the dislocation density, velocity and dislocation flux, as well as the dislocation correlations have been computed. The importance of the statistical measures introduced here in building continuum models of dislocation systems is highlighted.

  18. Dislocation of the hip (image)

    MedlinePlus

    A dislocation is an injury in which a bone is displaced from its proper position. Unless there are accompanying fractures or tissue damage, a simple dislocation may be manipulated back into place. Recovery may ...

  19. Supersonic Dislocation Bursts in Silicon

    DOE PAGESBeta

    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 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

  20. Supersonic Dislocation Bursts in Silicon.

    PubMed

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

    2016-01-01

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

  1. Supersonic Dislocation Bursts in Silicon

    PubMed Central

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

    2016-01-01

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

  2. Supersonic Dislocation Bursts in Silicon

    NASA Astrophysics Data System (ADS)

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

    2016-06-01

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

  3. [Spasm of the adductor muscles, pre-dislocations and dislocations of the hip joints in children and adolescents with cerebral palsy. Clinical observations on aetiology, pathogenesis, therapy and rehabilitation. Part II. The importance of the iliopsoas tendon, its tenotomy, of the coxa valga antetorta, and correction through osteotomy turning the hip into varus (author's transl)].

    PubMed

    Fettweis, E

    1979-02-01

    The following factors besides spasm and contraction of the adductor muscles contribute to the occurrence of dislocations of the hip in spastic paralysis: Spasm and contraction of the iliopsoas muscle and enhanced valgus position and antetorsion. The author holds the opinion that in case of malformation of the proximal end of the femur, it is not only the indirect action of the spastic musculature via the proximal femur-epiphyseal cartilage which is responsible for this phenomen in accordance with the law on functional adaption through longitudinal growth (Pauwels), but also the direct traction of the iliopsoas tendon. A clue in this direction is the often very pronounced elongation or enlargement of the trochanter minor. The author demonstrates the pathogenetic importance of iliopsoas contracture and malpositioning of the neck of the femur by means of analyses of the course in two patients. The following principles of treatment are postulated for spastic dislocation of the hip: Elimination of the pathogenetic factors through myotenotomy of the adductor muscles and complete resection of the obturator nerve, with observation of strict aftertreatment criteria, tenotomy of the iliopsoas, repositioning and osteotomy with turning into varus. Osteotomy without previous elimination of the pathogenetically acting muscular forces does not appear useful. Likewise, permanent re-positioning by means of muscle-relaxing operation cannot be sufficiently safe-guarded without additional osteotomy once the dislocation has taken place. In twelve patients with spastic dislocation of the hip, treated in accordance with these guidelines (two without osteotomy) aged 6 6/12 and 19 5/12 years, a roentgenologically good result was obtained in half of the cases, whereas the functional result was satisfactory not only with these patients but also with part of the other patients. If surgical treatment is instituted early enough, and if the experiences described here are taken into consideration

  4. Characterization of Microstructures across the Heat-Affected Zone of the Modified 9Cr-1Mo Weld Joint to Understand Its Role in Promoting Type IV Cracking

    NASA Astrophysics Data System (ADS)

    Laha, K.; Chandravathi, K. S.; Parameswaran, P.; Rao, K. Bhanu Sankara; Mannan, S. L.

    2007-01-01

    In the postweld heat-treated (PWHT) fusion welded modified 9Cr-1Mo steel joint, a soft zone was identified at the outer edge of the heat-affected zone (HAZ) of the base metal adjacent to the deposited weld metal. Hardness and tensile tests were performed on the base metal subjected to soaking for 5 minutes at temperatures below Ac1 to above Ac3 and tempering at the PWHT condition. These tests indicated that the soft zone in the weld joint corresponds to the intercritical region of HAZ. Creep tests were conducted on the base metal and cross weld joint. At relatively lower stresses and higher test temperatures, the weld joint possessed lower creep rupture life than the base metal, and the difference in creep rupture life increased with the decrease in stress and increase in temperature. Preferential accumulation of creep deformation coupled with extensive creep cavitation in the intercritical region of HAZ led to the premature failure of the weld joint in the intercritical region of the HAZ, commonly known as type IV cracking. The microstructures across the HAZ of the weld joint have been characterized to understand the role of microstructure in promoting type IV cracking. Strength reduction in the intercritical HAZ of the joint resulted from the combined effects of coarsening of dislocation substructures and precipitates. Constrained deformation of the soft intercritical HAZ sandwich between relatively stronger constitutes of the joint induced creep cavitation in the soft zone resulting in premature failure.

  5. Late Reconstruction of a Traumatic Trapeziometacarpal Dislocation with a Semi-constrained Prosthesis: A Case Report.

    PubMed

    Zollinger, Paul E

    2007-12-01

    Traumatic dislocation of the trapeziometacarpal joint is rare. A stable reduction should be accomplished as soon as possible, usually with K-wiring. In this case of persistent instability a semi-constrained prosthesis was applied successfully. PMID:26815093

  6. Dislocation dynamics in confined geometry

    NASA Astrophysics Data System (ADS)

    Gómez-García, D.; Devincre, B.; Kubin, L.

    1999-05-01

    A simulation of dislocation dynamics has been used to calculate the critical stress for a threading dislocation moving in a confined geometry. The optimum conditions for conducting simulations in systems of various sizes, down to the nanometer range, are defined. The results are critically compared with the available theoretical and numerical estimates for the problem of dislocation motion in capped layers.

  7. 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.

  8. Congenital hip dislocation (image)

    MedlinePlus

    ... by a blow, fall, or other trauma, a dislocation can also occur from birth. The cause is unknown but genetic factors may play a role. Problems resulting from very mild developmental dysplasia of the hip may not become apparent until the person is ...

  9. 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…

  10. [Reconstructions after inveterated fractures and dislocations of the foot].

    PubMed

    Zwipp, H

    2014-11-01

    Inveterated fractures or dislocations of the foot which are defined as being more than 6-12 weeks old can be secondarily reconstructed anatomically in only very rare cases. All other cases need reorientation of all axes of the foot requiring single or combined joint fusion. In cases of significant posttraumatic bone necrosis the dead bone has to be radically resected and substituted by an autogenous bone graft from the iliac crest. Old cases of dislocation, for example after subtalar dislocation without anatomical reduction, need reorientation of the foot axes by performing arthrodesis. Subluxation of the medial Lisfranc joint after an unrecognized rupture of Lisfranc ligament can be controlled later by anatomical repair of this ligament by using half of the extensor digitorum longus tendon and thus avoiding arthrodesis. PMID:25338655

  11. [Reconstructions after inveterated fractures and dislocations of the foot].

    PubMed

    Zwipp, H

    2014-01-01

    Inveterated fractures or dislocations of the foot which are defined as being more than 6-12 weeks old can be secondarily reconstructed anatomically in only very rare cases. All other cases need reorientation of all axes of the foot requiring single or combined joint fusion. In cases of significant posttraumatic bone necrosis the dead bone has to be radically resected and substituted by an autogenous bone graft from the iliac crest. Old cases of dislocation, for example after subtalar dislocation without anatomical reduction, need reorientation of the foot axes by performing arthrodesis. Subluxation of the medial Lisfranc joint after an unrecognized rupture of Lisfranc ligament can be controlled later by anatomical repair of this ligament by using half of the extensor digitorum longus tendon and thus avoiding arthrodesis. PMID:24441651

  12. Medial subtalar dislocation associated with fracture of the posterior process of the talus.

    PubMed

    Liu, Zhenjiang; Zhao, Qun; Zhang, Lijun

    2012-09-01

    A 17-year-old male sustained a medial subtalar fracture dislocation while playing basketball. The dislocation of the subtalar joint was reduced by closed means, but a large, comminuted, displaced posterior process fracture remained. Open reduction and internal fixation through a posteromedial approach was used to restore congruity to the subtalar joint. MRI at 12 months after injury showed no signs of avascular necrosis in the talus. PMID:22331059

  13. Right Ventricular Epicardial Fibrosis in Mice With Sternal Segment Dislocation.

    PubMed

    Adissu, H A; Medhanie, G A; Morikawa, L; White, J K; Newbigging, S; McKerlie, C

    2015-09-01

    We report coincident sternal segment dislocation and focally extensive right ventricular epicardial fibrosis observed during routine histopathology evaluation of C57BL/6N mice as part of a high throughput phenotyping screen conducted between 4 and 16 weeks of age. This retrospective case series study was conducted to determine whether cardiac fibrosis was a pathological consequence of sternal segment dislocation. We identified sternal segment dislocation in 51 of the total 1103 mice (4.6%) analyzed at 16 weeks of age. Males were more frequently affected. In all cases but 2, the dislocation occurred at the fourth intersternebral joint. In 42 of the 51 cases (82.4%), the dislocation was encased by regenerative cartilaginous callus that protruded internally into the thoracic cavity (intrathoracic callus) and/or externally to the outer aspect of the sternum (extrathoracic callus). Displacement of dislocated ends of the sternum into the thoracic cavity was present in 19 of 51 cases (36.5%). Coincident minimal or mild right ventricular epicardial and subepicardial fibrosis was observed in 22 of the 51 cases (43%) but was not observed in any of the mice in the absence of sternal segment dislocation. Our data suggest that right ventricular fibrosis was likely caused by direct injury of the right ventricle by the dislocated ends of the sternum and/or by intrathoracic callus that develops post dislocation. Potential pathogenesis for the sternal and cardiac lesions and their implication for the interpretation of phenotypes in mouse models of cardiopulmonary and skeletal disease are discussed. PMID:25281652

  14. Dislocation following total knee arthroplasty: A report of six cases

    PubMed Central

    Villanueva, Manuel; Ríos-Luna, Antonio; Pereiro, Javier; Fahandez-Saddi, Homid; Pérez-Caballer, Antonio

    2010-01-01

    Background: Dislocation following total knee arthroplasty (TKA) is the worst form of instability. The incidence is from 0.15 to 0.5%. We report six cases of TKA dislocation and analyze the patterns of dislocation and the factors related to each of them. Materials and Methods: Six patients with dislocation of knee following TKA are reported. The causes for the dislocations were an imbalance of the flexion gap (n=4), an inadequate selection of implants (n=1), malrotation of components (n=1) leading to incompetence of the extensor mechanism, or rupture of the medial collateral ligament (MCC). The patients presented complained of pain, giving way episodes, joint effusion and difficulty in climbing stairs. Five patients suffered posterior dislocation while one anterior dislocation. An urgent closed reduction of dislocation was performed under general anaesthesia in all patients. All patients were operated for residual instability by revision arthroplasty after a period of conservative treatment. Results: One patient had deep infection and knee was arthrodesed. Two patients have a minimal residual lag for active extension, including a patient with a previous patellectomy. Result was considered excellent or good in four cases and fair in one, without residual instability. Five out of six patients in our series had a cruciate retaining (CR) TKA designs: four were revised to a posterior stabilized (PS) TKA and one to a rotating hinge design because of the presence of a ruptured MCL. Conclusion: Further episodes of dislocation or instability will be prevented by identifying and treating major causes of instability. The increase in the level of constraint and correction of previous technical mistakes is mandatory. PMID:20924487

  15. Arthroscopic fixation of type III acromioclavicular dislocations.

    PubMed

    Somers, Jan F A; Van der Linden, Dietert

    2007-10-01

    Type III Acromio-Clavicular Joint dislocations can be treated successfully by surgical stabilisation in situ, with or without reconstruction of the coracoclavicular ligaments. The authors describe a simple and reliable mode of fixation, performed arthroscopically. The technique can be used for in situ fixation, or as part of an arthroscopically assisted Weaver and Dunn procedure. Using a metallic anchor loaded with a braided polyfilament suture, a strong and reliable fixation of the clavicle to the coracoid process is obtained. No hardware removal is necessary. Concomitant glenohumeral pathology can be treated simultaneously. PMID:18019910

  16. The management of bilateral posterior fracture dislocations of the shoulder: a case series illustrating management options

    PubMed Central

    Robinson, Peter W; Packham, Iain; Crowther, Mark

    2016-01-01

    Background Although dislocation of the shoulder is a relatively common event, the overwhelming majority of injuries are anterior. Posterior shoulder dislocation is more uncommon, comprising between 3% and 5% of all shoulder dislocations. One percent of shoulder dislocations involve a fracture, whereas only 0.9% of the 1500 cases reported by Neer (J Bone Joint Surg Am 1970; 52:1077–89; J Bone Joint Surg Am 1970; 52:1090–103) concerned posterior fracture dislocations. Bilateral posterior fracture dislocation is an even rarer event, comprising just 5% of all posterior fracture dislocations. Given the rarity and relative poor outcome often observed after these severe injuries, it is important that upper limb function is optimized. Methods Bilateral posterior fracture dislocations of the shoulder pose a difficult clinical challenge that requires careful management planning. To date, there have been three isolated case reports of using contralateral osteochondral humeral autograft and hemiarthroplasty. We report our experiences and clinical outcomes in managing four such cases using a variety and combination of treatments, including the first reported use of reverse shoulder arthroplasty with contralateral osteochondral humeral autografting. Results Shoulders reconstructed with humeral autograft demonstrated superior Oxford Shoulder Scores and an improved range of motion, as measured by a markerless machine vision system, compared to hemiarthroplasty. Conclusions Our results support the use of a contralateral humeral autograft in bilateral posterior shoulder fracture dislocation.

  17. Multiple spontaneous dislocations in a patient with Ehlers-Danlos syndrome.

    PubMed

    Dabbas, N; Saker, R; Blakeley, C

    2008-03-01

    Ehlers-Danlos syndrome (EDS) consists of a heterogeneous group of inherited connective tissue disorders, characterised by generalised joint hypermobility, hyperextensibility of the skin, dystrophic scars, and a tendency to excessive bleeding. Sequelae include recurrent low impact trauma dislocations, chronic joint pain, and early osteoarthritis. This report describes a case of multiple simultaneous dislocations at distant sites. We highlight the importance of paying consideration to the exposure of patients to large cumulative doses of ionising radiation to diagnose and confirm reduction of frequent dislocations, and ask whether radiographic confirmation is necessary on every occasion in this subset of patients. PMID:18299375

  18. Carpometacarpal dislocation of the thumb associated with fracture of the trapezium.

    PubMed

    Kose, Ozkan; Keskinbora, Mert; Guler, Ferhat

    2015-06-01

    Carpometacarpal dislocation (CMC) of the thumb associated with fracture of trapezium is an extremely rare injury, with only 12 cases that sustained similar injuries reported in the literature. In this article, another patient with this rare injury was reported, and all previously published cases were extensively reviewed. The presented case and all previously published cases had a longitudinally oriented trapezium fracture, which is naturally unstable and almost always associated with dislocation of the CMC joint. In contrast to previous descriptions, we believe that CMC joint dislocation and trapezium fracture are not two distinct pathologies that occur simultaneously by chance but share cause and consequence. PMID:24671487

  19. 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. PMID:27049181

  20. Elastodynamic image forces on dislocations

    PubMed Central

    Gurrutxaga-Lerma, Beñat; Balint, Daniel S.; Dini, Daniele; Sutton, Adrian P.

    2015-01-01

    The elastodynamic image forces on edge and screw dislocations in the presence of a planar-free surface are derived. The explicit form of the elastodynamic fields of an injected, quiescent screw dislocation are also derived. The resulting image forces are affected by retardation effects: the dislocations experience no image force for a period of time defined by the arrival and reflection at the free surface of the dislocation fields. For the case of injected, stationary dislocations, it is shown that the elastodynamic image force tends asymptotically to the elastotatic prediction. For the case of injected, moving dislocations, it is shown that the elastodynamic image force on both the edge and the screw dislocations is magnified by inertial effects, and becomes increasingly divergent with time; this additional effect, missing in the elastostatic description, is shown to be substantial even for slow moving dislocations. Finally, it is shown that the elastodynamic image force of an edge dislocation moving towards the surface at the Rayleigh wave speed becomes repulsive, rather than attractive; this is suggestive of instabilities at the core of the dislocation, and likely resonances with the free surface. PMID:26528080

  1. Thermodynamically consistent continuum dislocation dynamics

    NASA Astrophysics Data System (ADS)

    Hochrainer, Thomas

    2016-03-01

    Dislocation based modeling of plasticity is one of the central challenges at the crossover of materials science and continuum mechanics. Developing a continuum theory of dislocations requires the solution of two long standing problems: (i) to represent dislocation kinematics in terms of a reasonable number of variables and (ii) to derive averaged descriptions of the dislocation dynamics (i.e. material laws) in terms of these variables. The kinematic problem (i) was recently solved through the introduction of continuum dislocation dynamics (CDD), which provides kinematically consistent evolution equations of dislocation alignment tensors, presuming a given average dislocation velocity (Hochrainer, T., 2015, Multipole expansion of continuum dislocations dynamics in terms of alignment tensors. Philos. Mag. 95 (12), 1321-1367). In the current paper we demonstrate how a free energy formulation may be used to solve the dynamic closure problem (ii) in CDD. We do so exemplarily for the lowest order CDD variant for curved dislocations in a single slip situation. In this case, a thermodynamically consistent average dislocation velocity is found to comprise five mesoscopic shear stress contributions. For a postulated free energy expression we identify among these stress contributions a back-stress term and a line-tension term, both of which have already been postulated for CDD. A new stress contribution occurs which is missing in earlier CDD models including the statistical continuum theory of straight parallel edge dislocations (Groma, I., Csikor, F.F., Zaiser, M., 2003. Spatial correlations and higher-order gradient terms in a continuum description of dislocation dynamics. Acta Mater. 51, 1271-1281). Furthermore, two entirely new stress contributions arise from the curvature of dislocations.

  2. Treatment of chronic anterior locked glenohumeral dislocation with hemiarthroplasty

    PubMed Central

    Nicolas, Andrea Pujol; Liow, Raymond

    2014-01-01

    Restoring good shoulder function in an active patient with a chronic anterior locked dislocation of the glenohumeral joint can be challenging. This case report describes a 58-year-old active patient who presented with a very late missed locked anterior dislocation of the glenohumeral joint. He had coexisting large bony defects in the anterior glenoid and humeral head with resultant loss of motion and pain secondary to glenohumeral arthrosis. He underwent a humeral hemiarthroplasty, glenoid structural bone grafting, glenoid biological resurfacing and reinforcement of anterior capsule with the graft jacket to achieve a pain-free, stable, mobile joint with good range of movements and function. The clinical decision-making process and the surgical technique used in the management of this difficult condition are discussed.

  3. Design rules for dislocation filters

    SciTech Connect

    Ward, T.; Sánchez, A. M.; Beanland, R.; Tang, M.; Wu, J.; Liu, H.; Dunstan, D. J.

    2014-08-14

    The efficacy of strained layer threading dislocation filter structures in single crystal epitaxial layers is evaluated using numerical modeling for (001) face-centred cubic materials, such as GaAs or Si{sub 1−x}Ge{sub x}, and (0001) hexagonal materials such as GaN. We find that threading dislocation densities decay exponentially as a function of the strain relieved, irrespective of the fraction of threading dislocations that are mobile. Reactions between threading dislocations tend to produce a population that is a balanced mixture of mobile and sessile in (001) cubic materials. In contrast, mobile threading dislocations tend to be lost very rapidly in (0001) GaN, often with little or no reduction in the immobile dislocation density. The capture radius for threading dislocation interactions is estimated to be approximately 40 nm using cross section transmission electron microscopy of dislocation filtering structures in GaAs monolithically grown on Si. We find that the minimum threading dislocation density that can be obtained in any given structure is likely to be limited by kinetic effects to approximately 10{sup 4}–10{sup 5 }cm{sup −2}.

  4. Dislocation dynamics in nanocrystalline nickel.

    PubMed

    Shan, Z W; Wiezorek, J M K; Stach, E A; Follstaedt, D M; Knapp, J A; Mao, S X

    2007-03-01

    It is believed that the dynamics of dislocation processes during the deformation of nanocrystalline materials can only be visualized by computational simulations. Here we demonstrate that observations of dislocation processes during the deformation of nanocrystalline Ni with grain sizes as small as 10 nm can be achieved by using a combination of in situ tensile straining and high-resolution transmission electron microscopy. Trapped unit lattice dislocations are observed in strained grains as small as 5 nm, but subsequent relaxation leads to dislocation recombination. PMID:17359167

  5. Dynamic transitions in dislocation motion

    NASA Astrophysics Data System (ADS)

    Bulatov, Vasily; Cai, Wei; Marian, Jaime

    2003-03-01

    In a series of Molecular Dynamics simulations, we observe that, depending on stress, temperature and line length, screw dislocations in BCC iron move in three strikingly different regimes. Under low stress, the dislocations move smoothly via formation and migration of atomic-sized kinks; although widely believed, such motion mechanism has never been directly observed in full dynamic detail. Then, at a higher stress, dislocation motion suddenly becomes rough: the line becomes rugged and its motion becomes jerky producing in its wake a large amount of debris in the form of lattice vacancies and interstitial clusters. Remarkably, this bizarre behavior is not caused by any external factors, such as dislocation interaction with other crystal defects: the roughening transition is intrinsic to the dislocation itself. Under increasing stress the line raggedness and the amount of debris its motion produces continue to increase until, at some point, another dynamic transition takes place. The dislocation is now seen to cease at once its turbulent motion through the lattice and to initiate a thin plate of sheared crystal, a twin. The twin plate picks up where the dislocation just left off - it extends very fast in the same direction as dislocation motion and increases, gradually, in thickness. Notably, no more debris is produced during the twinning motion. The origin of these dynamic transitions, the underlying atomistic mechanisms of dislocation motion in all three regimes and their implication for strength of shocked materials are discussed.

  6. Smectic Edge Dislocations under Shear

    NASA Astrophysics Data System (ADS)

    Chen, Peilong; Lu, Chun-Yi David

    2011-09-01

    Layer structures around an edge dislocation in a smectic phase under shear are studied with both phase field and order parameter models. It is shown that, contrast to a crystal solid, the conventional picture of the Peach--Koehler force experienced by dislocations when the sample is under a shear stress cannot be readily applied to the smectic phases. Under a uniform shear flow, we obtain the phase field and order parameter solutions around an edge dislocation. The solutions elucidate properties such as the layer distortion range around the dislocation and scaling of inter-dislocation interaction on dislocation separation. Calculations on energy dissipation indicate the extreme shear-thinning behavior that an edge dislocation induces a shear stress independent of the shear rate. Finally in a bulk sample with dislocation forming loops and networks, we argue that the uniform flow component around the dislocation is important to the energy dissipation and we show that its scaling exponent with the shear rate is very close to results from many previous rheology measurements.

  7. Atlanto-occipital dislocation

    PubMed Central

    Hall, Graham C; Kinsman, Michael J; Nazar, Ryan G; Hruska, Rob T; Mansfield, Kevin J; Boakye, Maxwell; Rahme, Ralph

    2015-01-01

    Atlanto-occipital dislocation (AOD) is being increasingly recognized as a potentially survivable injury as a result of improved prehospital management of polytrauma patients and increased awareness of this entity, leading to earlier diagnosis and more aggressive treatment. However, despite overall improved outcomes, AOD is still associated with significant morbidity and mortality. The purpose of this paper is to review the biomechanical aspects, clinical features, radiologic criteria, and treatment strategies of AOD. Given that the diagnosis of AOD can be very challenging, a high degree of clinical suspicion is essential to ensure timely recognition and treatment, thus preventing neurological decline or death. PMID:25793163

  8. Lisfranc Dislocation having Bimalleolar Fracture with Syndesmotic Injury

    PubMed Central

    Ghate Sushant, D; Ashwin, Babar; Sistla, Vidyasagar M; Atul, Bhaskar

    2011-01-01

    Introduction: Fracture-dislocations of tarsometatarsal joints are rare. Association of these fractures with ankle injuries is very rare; to our knowledge not reported in the literature. Here, we report a rare case of Tarso-metatarsal (Lisfranc) dislocation with bimalleolar fracture with syndesmotic injury. Case report: Patient was treated with closed reduction and fixation of Lisfranc injury with combination of screws and k wires and also fixation of bimalleolar and syndesmotic injury. At follow up patient achieved excellent function as assessed by AOFAS (American Orthopaedic Society Foot and Ankle Society Midfoot Score). Conclusion: Even though extremely uncommon, early recognition of ankle injuries with uncommon lisfranc fractures & dislocations is important as prompt and simultaneous treatment of both injuries results in excellent clinical outcome.

  9. Current Concepts for Patellar Dislocation

    PubMed Central

    Petri, Maximilian; Ettinger, Max; Stuebig, Timo; Brand, Stephan; Krettek, Christian; Jagodzinski, Michael; Omar, Mohamed

    2015-01-01

    Context: Patellar dislocation usually occurs to the lateral side, leading to ruptures of the Medial Patellofemoral Ligament (MPFL) in about 90% of the cases. Even though several prognostic factors are identified for patellofemoral instability after patellar dislocation so far, the appropriate therapy remains a controversial issue. Evidence Acquisition: Authors searched the Medline library for studies on both surgical and conservative treatment for patellar dislocation and patellofemoral instability. Additionally, the reference list of each article was searched for additional studies. Results: A thorough analysis of the anatomical risk factors with a particular focus on patella alta, increased Tibial Tuberosity-Trochlear Groove (TT-TG) distance, trochlear dysplasia as well as torsional abnormalities should be performed early after the first dislocation to allow adequate patient counseling. Summarizing the results of all published randomized clinical trials and comparing surgical and conservative treatment after the first-time patellar dislocation until today indicated no significant evident difference for children, adolescents, and adults. Therefore, nonoperative treatment was indicated after a first-time patellar dislocation in the vast majority of patients. Conclusions: Surgical treatment for patellar dislocation is indicated primarily in case of relevant concomitant injuries such as osteochondral fractures, and secondarily for recurrent dislocations. PMID:26566512

  10. The role of TNXB single-nucleotide polymorphisms in recurrent shoulder dislocation.

    PubMed

    Geiger, Emanuel V; Henrich, Dirk; Wutzler, Sebastian; Schneidmüller, Dorien; Jakob, Heike; Frank, Johannes M; Marzi, Ingo

    2013-02-01

    Tenascin-X (TNX) is an extra-cellular matrix glycoprotein associated with collagen fibril deposition. Recent reports have linked truncated TNX mutations (TNXB) to generalized joint hypermobility and most importantly recurrent joint dislocation. In the present study, we investigated whether there is an association between joint dislocation recurrence rate and the frequency of TNXB single-nucleotide polymorphisms (SNPs). Seventy-eight patients treated for post-traumatic shoulder instability and 82 healthy controls were genotyped for selected TNXB SNP using TaqMan® Genotyping Assays. At a mean follow-up of 24 months recurrence rate and clinical outcomes were evaluated using the Constant and Murley, Rowe, and DASH scores. The association between genotypes and joint dislocation was tested using the dominant, recessive and additive models, and the model-free approach. Genotype distribution of the examined SNPs did not significantly deviate from the Hardy-Weinberg equilibrium (HWE) neither in patients nor in the controls. Moreover, there was no significant difference in genotype and allele distribution between patients and controls. Finally, no difference in genotype frequency was detected between patients who experienced a re-dislocation after the initial surgery and patients who did not sustain a re-dislocation. The SNPs investigated in this study have no clinically relevant influence on TNXB gene expression and/or TNX function. Therefore, these SNPs could not be used for predicting individual risk of recurrent shoulder dislocation. PMID:22991340

  11. [Post-traumatic bipolar dislocation of the clavicle: is operative treatment reasonable?].

    PubMed

    Dudda, M; Kruppa, C; Schildhauer, T A

    2013-02-01

    Bipolar dislocation of the clavicle ("floating clavicle") is extremely rare. It exists no standardised treatment for this trauma and the treatment is often conservative. This is mainly an anterior displacement of the sternoclavicular joint (type III according to Allman) and a posterior dislocation of the acromioclavicular joint (type IV according to Rockwood).We report on a 60 year old male who fell onto the right shoulder. He sustained a 'floating clavicle' and had a massive dislocation, impairment of range of motion and pain. Venous congestion was observable. We stabilised the dislocated acromioclavicular joint with a Balser's plate, the sternoclavicular joint was fixed with PDS cord tension band technique around the first rip and the sternum. In addition we resected the anterior part of the distal clavicle to get a better cosmetic result. Post-operatively the patient had an excellent range of motion without any further symptoms after six weeks and one year. Venous congestion was not more observable.In most of the cases dislocations of both ends of the clavicle are treated conservatively. We recommend an operative treatment especially in young and active patients to avoid re-dislocation and to archive better cosmetic results. PMID:22367519

  12. Dislocation Mechanics Under Extreme Pressures

    NASA Astrophysics Data System (ADS)

    Armstrong, Ronald; Arnold, Werner; Zerilli, Frank

    2007-06-01

    The shock-induced plasticity of copper, Armco iron, and tantalum materials is attributed to strain rate control by a substantial dislocation density being generated at the shock front. A thermal activation type constitutive equation is employed for the dislocation generation based on achievement of a limiting small activation volume for the process. A linear dependence of the equivalent compressive stress on logarithm of the plastic strain rate is predicted. The prediction compares favorably with Swegle-Grady and Meyers measurements previously fitted to a power law relationship. For Armco iron and tantalum, control is matched with a dislocation description of deformation twinning at the shock front. By comparison, the uniform shock-less loading in an isentropic compression experiment (ICE) provides for plastic strain rate control by the drag-resisted movement of mobile dislocations within the resident dislocation density.

  13. Complex and Unstable Simple Elbow Dislocations: A Review and Quantitative Analysis of Individual Patient Data

    PubMed Central

    de Haan, Jeroen; Schep, Niels; Tuinebreijer, Wim; den Hartog, Dennis

    2010-01-01

    Objective: The primary objective of this review of the literature with quantitative analysis of individual patient data was to identify the results of available treatments for complex elbow dislocations and unstable simple elbow dislocations. The secondary objective was to compare the results of patients with complex elbow dislocations and unstable elbow joints after repositioning of simple elbow dislocations, which were treated with an external fixator versus without an external fixator. Search Strategy: Electronic databases MEDLINE, EMBASE, LILACS, and the Cochrane Central Register of Controlled Trials. Selection Criteria: Studies were eligible for inclusion if they included individual patient data of patients with complex elbow dislocations and unstable simple elbow dislocations. Data Analysis: The different outcome measures (MEPI, Broberg and Morrey, ASES, DASH, ROM, arthritis grading) are presented with mean and confidence intervals. Main Results: The outcome measures show an acceptable range of motion with good functional scores of the different questionnaires and a low mean arthritis score. Thus, treatment of complex elbow dislocations with ORIF led to a moderate to good result. Treatment of unstable simple elbow dislocations with repair of the collateral ligaments with or without the combination of an external fixator is also a good option. The physician-rated (MEPI, Broberg and Morrey), patient-rated (DASH) and physician- and patient-rated (ASES) questionnaires showed good intercorrelations. Arthritis classification by x-ray is only fairly correlated with range of motion. Elbow dislocations are mainly on the non-dominant side. PMID:20361035

  14. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2015-12-01

    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.

  16. Perilunate Injuries, Not Dislocated (PLIND)

    PubMed Central

    Herzberg, Guillaume

    2013-01-01

    Purpose We reviewed a series of equivalents of perilunate dislocations and fracture-dislocations (PLDs–PLFDs) in which there was no dislocation of the capitate from the lunate on the initial radiographs. We propose to include these injuries as a variant of perilunate dislocations that we have termed a perilunate injury, not dislocated (PLIND) lesion in a modified classification of perilunate injuries. Methods A review of the records of all acute perilunate injuries and displaced carpal fractures was done in a single-center university hospital wrist surgery unit over a 5-year period. All cases presenting at the acute stage with displaced fractures of scaphoid, lunate, triquetrum, or capitate along with scapholunate and/or lunotriquetral dissociation but no dislocation of the capitate from the lunate in the sagittal or coronal plane were reviewed and considered as PLIND lesions. Results We identified 11 patients with PLIND lesions. Three cases with clinical and radiological follow-up are presented. Discussion Equivalents of PLDs–PLFDs presenting without dislocation of the capitate from the lunate do exist. These injuries may be overlooked despite their severity. They require both osseous and ligamentous repair. Including them into an existing perilunate injuries classification highlights their recognition and enables a better understanding and treatment of both acute and chronic nondislocated perilunate injuries. Level of Evidence Level IV, retrospective case series. PMID:24436839

  17. Fractures and dislocations of the midfoot: Lisfranc and Chopart injuries.

    PubMed

    Benirschke, Stephen K; Meinberg, Eric G; Anderson, Sarah A; Jones, Clifford B; Cole, Peter A

    2013-01-01

    The midfoot is a complex association of five bones and many articulations between the forefoot metatarsals and the talus and calcaneus, which make up the hindfoot. These anatomic relationships are connected and restrained by an even more complex network of ligaments, capsules, and fascia, which must function as a unit to provide normal and painless locomotion. The common eponyms of Lisfranc and Chopart refer to the distal and proximal joint relationships of the midfoot, respectively. Midfoot injuries range from single ligament strains to complicated fracture-dislocations involving multiple bones and joints. To provide best outcomes for patients, it is important to understand the anatomy and the mechanical function of the midfoot; to review the epidemiology, mechanism, and classification of injuries encountered in an orthopaedic clinical practice; and to review the principles, indications, and surgical techniques for managing midfoot fractures and dislocations. PMID:23395016

  18. Functional treatment versus plaster for simple elbow dislocations (FuncSiE): a randomized trial

    PubMed Central

    2010-01-01

    Background Elbow dislocations can be classified as simple or complex. Simple dislocations are characterized by the absence of fractures, while complex dislocations are associated with fractures. After reduction of a simple dislocation, treatment options include immobilization in a static plaster for different periods of time or so-called functional treatment. Functional treatment is characterized by early active motion within the limits of pain with or without the use of a sling or hinged brace. Theoretically, functional treatment should prevent stiffness without introducing increased joint instability. The primary aim of this randomized controlled trial is to compare early functional treatment versus plaster immobilization following simple dislocations of the elbow. Methods/Design The design of the study will be a multicenter randomized controlled trial of 100 patients who have sustained a simple elbow dislocation. After reduction of the dislocation, patients are randomized between a pressure bandage for 5-7 days and early functional treatment or a plaster in 90 degrees flexion, neutral position for pro-supination for a period of three weeks. In the functional group, treatment is started with early active motion within the limits of pain. Function, pain, and radiographic recovery will be evaluated at regular intervals over the subsequent 12 months. The primary outcome measure is the Quick Disabilities of the Arm, Shoulder, and Hand score. The secondary outcome measures are the Mayo Elbow Performance Index, Oxford elbow score, pain level at both sides, range of motion of the elbow joint at both sides, rate of secondary interventions and complication rates in both groups (secondary dislocation, instability, relaxation), health-related quality of life (Short-Form 36 and EuroQol-5D), radiographic appearance of the elbow joint (degenerative changes and heterotopic ossifications), costs, and cost-effectiveness. Discussion The successful completion of this trial will

  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. PMID:27139130

  20. Moving Dislocations in Disordered Alloys.

    SciTech Connect

    Marian, J; Caro, A

    2006-11-18

    Using atomistic simulations of dislocation motion in Ni and Ni-Au alloys we report a detailed study of the mobility function as a function of stress, temperature and alloy composition. We analyze the results in terms of analytic models of phonon radiation and their selection rules for phonon excitation. We find a remarkable agreement between the location of the cusps in the {sigma}-v relation and the velocity of waves propagating in the direction of dislocation motion. We identify and characterize three regimes of dissipation whose boundaries are essentially determined by the direction of motion of the dislocation, rather than by its screw or edge character.

  1. Acromioclavicular joint reconstruction with coracoacromial ligament transfer using the docking technique

    PubMed Central

    Millett, Peter J; Braun, Sepp; Gobezie, Reuben; Pacheco, Iván H

    2009-01-01

    Background Symptomatic Acromioclavicular (AC) dislocations have historically been surgically treated with Coracoclavicular (CC) ligament reconstruction with transfer of the Coracoacromial (CA) ligament. Tensioning the CA ligament is the key to success. Methods Seventeen patients with chronic, symptomatic Type III AC joint or acute Type IV and V injuries were treated surgically. The distal clavicle was resected and stabilized with CC ligament reconstruction using the CA ligament. The CA ligament was passed into the medullary canal and tensioned, using a modified 'docking' technique. Average follow-up was 29 months (range 12–57). Results Postoperative ASES and pain significantly improved in all patients (p = 0.001). Radiographically, 16 (94%) maintained reduction, and only 1 (6%) had a recurrent dislocation when he returned to karate 3 months postoperatively. His ultimate clinical outcome was excellent. Conclusion The docking procedure allows for tensioning of the transferred CA ligament and healing of the ligament in an intramedullary bone tunnel. Excellent clinical results were achieved, decreasing the risk of recurrent distal clavicle instability. PMID:19144190

  2. Fracture of the Greater Trochanter during Closed Reduction of Obturator Type Hip Dislocation

    PubMed Central

    Yang, Jae-Hyuk; Pandher, Dilbans Singh

    2014-01-01

    Obturator (Inferior) type dislocation of the hip joint is a rare and the fracture of greater trochanter during closed reduction for it has never been reported in literature. In this report, we present a case of a fracture of greater trochanter during difficult closed reduction which required operative fixation. Surgeons need to be aware of this complication and excessive force for reduction should be avoided when treating of this type dislocation.

  3. Ankle dislocation without accompanying malleolar fracture. A case report.

    PubMed

    Hatori, Masahito; Kotajima, Satoshi; Smith, Richard A; Kokubun, Shoichi

    2006-01-01

    Dislocation of the tibiotalar joint without associated fracture is rare. We present here a 21-year-old man who sustained open posteromedial dislocation of the left ankle without malleolar facture when he jumped and sprained his right ankle while playing basketball. The most likely mechanism is forced flexion applied to the ankle joint leading to a rupture of the anterior capsule and lateral structures of the ankle followed by an accelerating inversion stress leading to a posteromedial dislocation of the talus from the tibial condyle. Transient paresthesia was noted in the area of the superficial peroneal nerve. At surgery, the anterior part of the tibiotalar joint capsule and anterior talofibular ligament were detached from their original sites. The calcaneofibular ligament was also detached with its associated periosteum and a tiny avulsed bony fragment. The articular facets of the tibia and talus were intact. The treatment consisted of wound irrigation, debridement, reduction and capsular suture followed by immobilization with a short leg cast. About 10 degrees of loss in the range of dorsiflexion was observed. The patient achieved good long-term functional results. PMID:16961183

  4. Irreducible posterolateral dislocation of the knee: a case report

    PubMed Central

    SOLARINO, GIUSEPPE; NOTARNICOLA, ANGELA; MACCAGNANO, GIUSEPPE; PIAZZOLLA, ANDREA; MORETTI, BIAGIO

    2015-01-01

    Irreducible posterolateral dislocations of the knee are rare lesions, generally caused by high-energy trauma inducing rotational stress and a posterior and lateral displacement of the tibia. In these conditions, the interposition of abundant soft tissue inside the enlarged medial joint space prevents spontaneous reduction or non-surgical treatment by manipulation of the dislocation. Surgical treatment is therefore compulsory. We report the clinical case of a woman who suffered a subluxation of the knee while jogging. The case we describe is of interest because it shows that even less severe knee dislocations, like this subluxation caused by a low-velocity sports trauma, may present in an irreducible form requiring open surgery. Clinical-instrumental monitoring did not reveal any signs of vascular or nerve injury. Owing to the irreducibility of the lesion we were obliged to perform open surgery in order to free the joint from the interposed muscle tissue and repair medial capsule-ligament lesions. Repair of the damaged cruciate ligaments was deferred to a second stage, but ultimately rendered necessary by the persistence of joint instability and the need to address the patient’s functional needs. In the literature, different one- and two-step surgical options, performed by arthroscopy or arthrotomy, are reported for such related problems. The Authors discuss these various options and examine and discuss their own decision taken during the surgical work-up of this case. PMID:26605258

  5. Unilateral Congenital Knee and Hip Dislocation with Bilateral Clubfoot - A rare Packaging disorder

    PubMed Central

    Tiwari, Mukesh; Sharma, Nishith

    2013-01-01

    Introduction: Reduced intrauterine space gives rise to ‘packaging disorder’ which may involve joint dislocations or contractures. We present an unique case where mutiple joints were dislocated involving left congenital knee dislocation (CDK), bilateral congenital hip dislocation (CDH) and congenital talipes equino varus (CTEV)deformities. Case Report: A preterm baby boy born to mother with diagnosed oligohydramios presented with left CDK bilateral DDH and CTEV. The knee dislocation was treated first with gradual streaching and weekly above knee cast. At 7th week good flexion was achieved at both knees and abduction splint for DDH (using double diaper) with ponseti cast for CTEV was done. At one year follow up all joints were reduced and maintained well with baby able to stand with support. Conclusion: Packaging disorders may present with multiple dislocations and deformities. Early intervention with serial casting and manipulation minimises disability and prevents ambulatory problems. In our case there was a good response to manipulation and serial casting. This differs from cases with inherent pathology like arthrogryposis where response to treatment is not so good PMID:27298901

  6. A rare case of floating clavicle and a novel technique for stabilizing the sternoclavicular joint

    PubMed Central

    Webb, Mark; Wallace, Angus

    2014-01-01

    We present the first ever case report of a floating clavicle with a unique combination of a posterior sternoclavicular joint dislocation and an associated grade III acromioclavicular joint dislocation. We treated this injury surgically by stabilizing both ends of clavicle using a polyester surgical mesh device (LockDown™; Mandaco 569 Limited, Redditch, UK; previously called the Nottingham Surgilig).

  7. 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 ...

  8. 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.

  9. Asymmetric Bilateral Hip Dislocations: A Case Report and Historical Review of the Literature

    PubMed Central

    Buckwalter, Joseph; Westerlind, Brian; Karam, Matthew

    2015-01-01

    Background Asymmetric bilateral hip dislocations are a rare injury pattern in which one hip dislocates posteriorly, and the contralateral hip dislocates anteriorly. We report a case of bilateral asymmetric hip dislocations and provide a comprehensive review of all available reports, identifying 104 total cases, which is 70 more than previously reported. Purpose To review and evaluate the total body of literature regarding bilateral asymmetric hip dislocations. Methods Comprehensive literature review and analysis of all reports of bilateral asymmetric hip dislocations with concurrent case report. Results and Conclusions Bilateral, asymmetric represent approximately 0.01%–0.02% of all joint dislocations. There has been a substantial increase in the number of case reports in the literature in the last 10 years. Males are more likely than females to incur this injury pattern and the most common mode of injury is motor vehicle accident Urgent closed reduction should be attempted in an efficient and safe manner to avoid potential complications, and open reduction should be considered in irreducible dislocations. Post reduction management should include stability assessment and CT to assess for associated injuries and intraarticular fragments; although no clear guidelines for post-reduction treatment emerged. Common complications include: nerve palsies, AVN and heterotopic ossification. PMID:26361448

  10. 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. PMID:27107998

  11. Dislocations in Monolayers and Semiconductors.

    NASA Astrophysics Data System (ADS)

    Ren, Qiang

    1995-01-01

    Four different aspects of the properties of dislocations in monolayer and semiconductors have been investigated: (i) Using atomic relaxation techniques, dislocation dipoles of various sizes and orientations have been studied for monolayers with the Lennard-Jones potential (LJP) and the nearest-neighbour piecewise linear force (PLF) interactions. In the WP system the lower energy vacancy dipoles have over a wide range of angles an energy which is mainly a function of the vacancy content of the dipole. There is a competition between the elastic forces and the topological constraints which favour a five-fold coordinate vacancy (FCV) at the centre of each core. For the short range PLF system the lattice usually compresses upon the introduction of a dislocation, a consequence of the soft core of the interaction potential, and interstitial dipoles are lower in energy. For the long range LJP system the dislocations are mobile whereas for the PLF system they are pinned. The relevance of these results to existing theories of melting are discussed. (ii) Using generalized stacking-fault (GSF) energies obtained from first-principles density-functional calculations, a zero-temperature model for dislocations in silicon is constructed within the framework of a Peierls-Nabarro (PN) model. Core widths, core energies, PN pinning energies, and stresses are calculated for various possible perfect and imperfect dislocations. Both shuffle and glide sets are considered. 90^circ partials are shown to have a lower Peierls stress (PS) than 30 ^circ partials in accord with experiment. (iii) We have also studied by atomic relaxation techniques the properties of dislocations in silicon, modelled by the empirical potential of Stillinger and Weber. In order to compare with the preceding calculation no reconstruction is allowed. We find no evidence of dissociation in the shuffle dislocations. Within this model shuffle dislocations glide along their slipping planes. On the other hand, glide sets

  12. Treatment of recurrent TMJ dislocation in geriatric patient by autologous blood – A technique revisited

    PubMed Central

    Gupta, Deepak; Rana, Amar Singh; Verma, Varun Kumar

    2012-01-01

    A number of techniques have been advocated for the treatment of recurrent temporomandibular joint dislocation. Autologous blood injection around the articular capsule and/or into the articular cavity, which is one of the treatment modality, was recently reintroduced. We report a case of 82-year-old female with bilateral recurrent temporomandibular joint dislocation, treated by technique of autologous blood injection. The outcome was successful and required no further treatment in eight months follow up, thus the procedure had proven to be safe, simple, minimally invasive and cost effective. PMID:25737879

  13. 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.

  14. A hinged external fixator for complex elbow dislocations: A multicenter prospective cohort study

    PubMed Central

    2011-01-01

    Background Elbow dislocations can be classified as simple or complex. Simple dislocations are characterized by the absence of fractures, while complex dislocations are associated with fractures of the radial head, olecranon, or coronoid process. The majority of patients with these complex dislocations are treated with open reduction and internal fixation (ORIF), or arthroplasty in case of a non-reconstructable radial head fracture. If the elbow joint remains unstable after fracture fixation, a hinged elbow fixator can be applied. The fixator provides stability to the elbow joint, and allows for early mobilization. The latter may be important for preventing stiffness of the joint. The aim of this study is to determine the effect of early mobilization with a hinged external elbow fixator on clinical outcome in patients with complex elbow dislocations with residual instability following fracture fixation. Methods/Design The design of the study will be a multicenter prospective cohort study of 30 patients who have sustained a complex elbow dislocation and are treated with a hinged elbow fixator following fracture fixation because of residual instability. Early active motion exercises within the limits of pain will be started immediately after surgery under supervision of a physical therapist. Outcome will be evaluated at regular intervals over the subsequent 12 months. The primary outcome is the Quick Disabilities of the Arm, Shoulder, and Hand score. The secondary outcome measures are the Mayo Elbow Performance Index, Oxford Elbow Score, pain level at both sides, range of motion of the elbow joint at both sides, radiographic healing of the fractures and formation of periarticular ossifications, rate of secondary interventions and complications, and health-related quality of life (Short-Form 36). Discussion The outcome of this study will yield quantitative data on the functional outcome in patients with a complex elbow dislocation and who are treated with ORIF and

  15. 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.

  16. Patellar dislocation with genu valgum treated by DFO.

    PubMed

    Kwon, Jae Ho; Kim, Jong In; Seo, Dong-Hyun; Kang, Kyung-Woon; Nam, Ji Ho; Nha, Kyung-Wook

    2013-06-01

    Congenital habitual patellar dislocation is a rare condition of the knee where the patella dislocates during flexion and relocates during extension. The congenital form is permanent, irreducible, and presents at birth. It is characterized by a short quadriceps and a major patellofemoral dysplasia and short height. This article presents a rare case of a 27-year-old woman with recurring bilateral habitual dislocation of the patella after a failed previous proximal and distal realignment procedure. Clinical examinations of both knees revealed genu valgus knees and lateral joint pain that recurred after several previous operations. Radiographs of both knees showed patellar dislocation and genu valgum associated with patellofemoral dysplasia and osteoarthritis of the lateral compartment. Long-leg standing radiographs showed an anatomic tibiofemoral angle of right 13° and left 6° valgus and a mechanical tibiofemoral angle of right 8° and left 2° valgus and weight-bearing line of 65% on the right and 48% on the left. The authors performed a distal femoral closing wedging osteotomy to correct the valgus deformity, and then percutaneous lateral release and medial reefing were performed to stabilize the patellas of both knees simultaneously. PMID:23746026

  17. Multiscale Theory of Dislocation Climb

    NASA Astrophysics Data System (ADS)

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

    2015-12-01

    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.

  18. 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. PMID:26765003

  19. 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...

  20. 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...

  1. 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...

  2. 21 CFR 888.3310 - Hip joint metal/polymer constrained cemented or uncemented prosthesis.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Hip joint metal/polymer constrained cemented or... Hip joint metal/polymer constrained cemented or uncemented prosthesis. (a) Identification. A hip joint... replace a hip joint. The device prevents dislocation in more than one anatomic plane and has...

  3. 21 CFR 888.3310 - Hip joint metal/polymer constrained cemented or uncemented prosthesis.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Hip joint metal/polymer constrained cemented or... Hip joint metal/polymer constrained cemented or uncemented prosthesis. (a) Identification. A hip joint... replace a hip joint. The device prevents dislocation in more than one anatomic plane and has...

  4. 21 CFR 888.3310 - Hip joint metal/polymer constrained cemented or uncemented prosthesis.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Hip joint metal/polymer constrained cemented or... Hip joint metal/polymer constrained cemented or uncemented prosthesis. (a) Identification. A hip joint... replace a hip joint. The device prevents dislocation in more than one anatomic plane and has...

  5. Tarsometatarsal/Lisfranc joint.

    PubMed

    DiDomenico, Lawrence A; Cross, Davi

    2012-04-01

    Accurate early diagnosis with adequate reduction and maintenance of anatomic alignment of the dislocation or fracture within the Lisfranc joint complex have been found to be the key to successful outcomes regarding this injury. Because of the anatomic variations, the thin soft tissue envelop, and the abundance of ligamentous and capsular structures in the region, repair of these injuries can be a challenge. The classification systems used to describe these injuries aid in describing the mechanism of injury or displacement type present, which may aid in determining what treatment modality can provide the best outcome. PMID:22424486

  6. 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

  7. Subtalar dislocation secondary to a low energy injury.

    PubMed

    McKeag, Philip; Lyske, Jonathan; Reaney, Jonathan; Thompson, Neville

    2015-01-01

    An 18-year-old young man presented with an ankle injury, after landing on a supinated right foot following jumping while playing football. A plain X-ray revealed a medial subtalar dislocation. Despite obvious ankle deformity, the surrounding skin remained intact. Closed reduction of the subtalar joint was successfully performed under general anaesthesia in theatre. A CT of the ankle, after reduction, demonstrated a non-displaced fracture of the neck of the talus; no osteochondral defect was observed. This was successfully managed conservatively, with immobilisation of the ankle, in a non-weight bearing cast for 6 weeks. This case highlights that subtalar dislocation may follow a low-energy mechanism and that such injuries can be managed without open reduction. PMID:25650063

  8. Drift of dislocation tripoles under ultrasound influence.

    PubMed

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

    2016-01-01

    Numerical simulations of dynamics of different stable dislocation tripoles under influence of monochromatic standing sound wave were performed. The basic conditions necessary for the drift and mutual rearrangements between dislocation structures were investigated. The dependence of the drift velocity of the dislocation tripoles as a function of the frequency and amplitude of the external influence was obtained. The results of the work can be useful in analysis of motion and self-organization of dislocation structure under ultrasound influence. PMID:26278625

  9. Light scattering from dislocations in silicon

    NASA Astrophysics Data System (ADS)

    Monier, Vanessa; Capello, Luciana; Kononchuk, Oleg; Pichaud, Bernard

    2010-11-01

    Nondecorated glide dislocations in Czochralski grown silicon have been studied by laser scattering tomography technique. Dependence of intensity of scattered light on polarization of the incident light has been measured for different orientations of the dislocation line and Burgers vector. Detailed theory of light scattering by dislocation in silicon crystals is presented. It is shown that by combination of polarization and tomography measurements it is possible to determine slip system of nondecorated mixed dislocation in Si.

  10. Arthroscopic Lysis of Arthrofibrosis of the Fifth Tarsometatarsal Joint

    PubMed Central

    Lui, Tun Hing

    2015-01-01

    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. PMID:26870650

  11. 14 CFR 314.6 - Qualifying dislocation.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 4 2010-01-01 2010-01-01 false Qualifying dislocation. 314.6 Section 314.6 Aeronautics and Space OFFICE OF THE SECRETARY, DEPARTMENT OF TRANSPORTATION (AVIATION PROCEEDINGS) PROCEDURAL REGULATIONS EMPLOYEE PROTECTION PROGRAM General § 314.6 Qualifying dislocation. A qualifying dislocation is...

  12. Radial head button holing: a cause of irreducible anterior radial head dislocation.

    PubMed

    Shin, Su-Mi; Chai, Jee Won; You, Ja Yeon; Park, Jina; Bae, Kee Jeong

    2016-10-01

    "Buttonholing" of the radial head through the anterior joint capsule is a known cause of irreducible anterior radial head dislocation associated with Monteggia injuries in pediatric patients. To the best of our knowledge, no report has described an injury consisting of buttonholing of the radial head through the annular ligament and a simultaneous radial head fracture in an adolescent. In the present case, the radiographic findings were a radial head fracture with anterior dislocation and lack of the anterior fat pad sign. Magnetic resonance imaging (MRI) clearly demonstrated anterior dislocation of the fractured radial head through the torn annular ligament. The anterior joint capsule and proximal portion of the annular ligament were interposed between the radial head and capitellum, preventing closed reduction of the radial head. Familiarity with this condition and imaging findings will aid clinicians to make a proper diagnosis and fast decision to perform an open reduction. PMID:27502623

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

    PubMed Central

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

    2015-01-01

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

  14. Distal radioulnar joint injuries.

    PubMed

    Thomas, Binu P; Sreekanth, Raveendran

    2012-09-01

    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

  15. Interaction of <1 0 0> dislocation loops with dislocations studied by dislocation dynamics in α-iron

    NASA Astrophysics Data System (ADS)

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

    2015-05-01

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

  16. Tribological behavior of electron beam D6ac weldment

    NASA Astrophysics Data System (ADS)

    Wu, Shyh-Chi; Tseng, Kuang-Hung; Wen, Hua-Chiang; Wu, Ming-Jhang; Chou, Chang-Pin

    2013-01-01

    A flow formed D6ac steel tubing was joined using electron beam (EB) welding. Thereafter, the EB weldments were treated by tempering at temperatures of 450 °C and 550 °C. After tempering, the microstructural features, mechanical properties, and tribological characteristics of the EB D6ac weldment were studied. This study used a scratch test to evaluate the sliding wear resistance of the tempered weldment. Results indicate that the tempering softens the microstructure by reducing the dislocation density of the flow formed D6ac steel. For the 450 °C/2 h/air cooling tempering treated D6ac steel, the fracture toughness of the EB weldment can be significantly improved. The tribological behavior of the tempered D6ac weldment depended on the tempered microstructures.

  17. 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.

  18. [Anterior dislocation of the fibula resulting from surgical malreduction: a case report].

    PubMed

    Wang, Z Y; Wu, X B

    2016-04-18

    Ankle joint fracture is one of the most common types of fracture. There are many researches on the injury mechanism, treatment principles and surgical techniques. A type of injury which combines posterior dislocation of fibula, known as the Bosworth injury, is relatively rare. In 1947, Bosworth first described this type of injury as an unusual ankle fracture dislocation with fixed posterior fracture dislocation of the distal part of the fibula. In this type of fracture, the proximal fibular shaft fragment locks behind the tibialis posterior tubercle. This rare ankle fracture variant is often not recognized in initial radiographs and requires a computed tomographic (CT) scan for verification. But there are already many reports, discussing the injury mechanism, treatment principles and surgical techniques. However, there are few reports of anterior dislocation of the fibula, caused by either injury or surgery. The mechanism of the injury is still not clear. This article reports a case of anterior dislocation of the fibula. We report a patient with left ankle open fracture (Lauge-Hansen pronation-external rotation stage III, Gustilo IIIA). Open reduction and internal fixation was done in the initial surgery, but ended up with poor reduction, resulting in fibula anterior dislocation, anterior dislocation of talus and tibia fibular dislocation. The fibula was dislocated anteriorly of the tibia, which rarely happened. The patient suffered severe ankle joint dysfunction. The second operation took out the original internal fixation, reduced the fracture, and reset the internal fixation. The function of ankle joint was improved obviously after operation. But because of the initial injury and the two operations, the soft tissue around the fracture was greatly damaged. 6 months after the second operation, and the fracture still not healed, so the bone graft was carried out in the third surgery. Two months after the third surgery, the function of the ankle was significantly

  19. Discrete dislocation dynamics simulations in a cylinder

    NASA Astrophysics Data System (ADS)

    Li, Maosheng; Gao, Chan; Xu, Jianing

    2015-02-01

    Mechanical properties of material are closely related to the motion of dislocations, and predicting the interactions and resulting collective motion of dislocations is a major task in understanding and modelling plastically deforming materials. A discrete dislocation dynamics model is used to describe the orientation substructure within the microstructure. Discrete dislocation dynamics simulations in three dimensions have been used to examine the role of dislocation multiplication and mobility on the plasticity in small samples under uniaxial compression. In this paper we describe the application of the dislocation dynamics simulations in a cylindrical geometry. The boundary conditions for the simulation were estimated from the distribution of the geometrically necessary dislocation density which was obtained from the orientation map. Numerical studies benchmark could validate the accuracy of the algorithms and the importance of handling the singularity correctly. The results of the simulation explain the formation of the experimentally observed substructure.

  20. Dislocation boundaries and active slip systems

    SciTech Connect

    Wert, J.A.; Hansen, N.

    1995-11-01

    Part of the dislocations which have participated in the plastic deformation of a polycrystalline metal are stored in dislocation boundaries in a two- or three-dimensional arrangement. The dislocation in such boundaries can be analyzed by determining the misorientation between neighboring crystallites and the boundary orientation. Information about the dislocations in the boundaries can also be obtained by an analysis of active slip systems based on the crystallite orientation and the imposed stress or strain state in combination with appropriate constraint conditions. In the present paper an analysis of the boundary dislocation structure and of the slip systems has been conducted for pure aluminium cold-rolled to a von Mises strain of 0.41. The results show that a substantial majority of dislocations in different types of dislocation boundaries are from the primary and conjugate slip system in the adjoining crystallites. A basis is therefore provided for integrating deformation structure observations with plastic deformation behavior.

  1. 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.

  2. Diabetic Lisfranc fracture-dislocations and Charcot neuroarthropathy.

    PubMed

    Levitt, Bradley A; Stapleton, John J; Zgonis, Thomas

    2013-04-01

    The goal with Lisfranc fracture-dislocations is to regain joint congruity and reestablish midfoot stability to avoid debilitating posttraumatic arthrosis and chronic pain in the sensate patient. In the diabetic population, dense peripheral neuropathy and/or vascular disease are equally important and may alter the surgical approach to traumatic tarsometatarsal injuries. The initial diagnosis in the diabetic population may be delayed due to subtle radiographic findings and/or patient unawareness of trauma in the insensate foot. Failure to initiate treatment in the early stages of acute diabetic neuropathic Lisfranc injuries can predispose the patient to midfoot instability, potential ulceration, infection, and Charcot neuroarthropathy. PMID:23465814

  3. Dislocation creep of dry quartz

    NASA Astrophysics Data System (ADS)

    Kilian, Rüdiger; Heilbronner, Renée.; Holyoke, Caleb W.; Kronenberg, Andreas K.; Stünitz, Holger

    2016-05-01

    Small-scale shear zones within the Permian Truzzo meta-granite developed during the Alpine orogeny at amphibolite facies conditions. In these shear zones magmatic quartz deformed by dislocation creep and recrystallized dynamically by grain boundary migration with minor subgrain rotation recrystallization to a grain size of around 250-750 µm, consistent with flow at low differential stresses. Fourier transform infrared (FTIR) spectroscopy reveals very low water contents in the interior of recrystallized grains (in the form of discrete OH peaks, ~20 H/106Si and very little broad band absorption, <100 H/106Si). The spectral characteristics are comparable to those of dry Brazil quartz. In FTIR spectra, magmatic quartz grains show a broad absorption band related with high water concentrations only in those areas where fluid inclusions are present while other areas are dry. Drainage of fluid inclusions and synkinematic growth of hydrous minerals indicates that a hydrous fluid has been available during deformation. Loss of intragranular water during grain boundary migration recrystallization did not result in a microstructure indicative of hardening. These FTIR measurements provide the first evidence that quartz with extremely low intragranular water contents can deform in nature by dislocation creep at low differential stresses. Low intragranular water contents in naturally deformed quartz may not be necessarily indicative of a high strength, and the results are contrary to implications taken from deformation experiments where very high water contents are required to allow dislocation creep in quartz. It is suggested that dislocation creep of quartz in the Truzzo meta-granite is possible to occur at low differential stresses because sufficient amounts of intergranular water ensure a high recovery rate by grain boundary migration while the absence of significant amounts of intragranular water is not crucial at natural conditions.

  4. Misfit dislocation nucleation in heteroepitaxy

    NASA Astrophysics Data System (ADS)

    Trushin, Oleg; Ying, See Chen; Granato, Enzo; Ala-Nissila, Tapio

    2001-03-01

    We have studied atomic mechanisms of misfit dislocation nucleation in heteroepitaxy with semiempirical potentials. Many-body mechanisms of stress relaxation are systematically investigated with Lennard-Jones potential in 2D and 3D cases. Energy barriers for dislocation nucleation are estimated using modern methods for saddle point search (Nudged Elastic Band [1], Eigenvector Following [2] and others). Moreover, new simple and effective method for transition paths searching is proposed. Based on the data the critical thickness of film is estimated as a function of film-substrate lattice misfit. Moreover, to make the study more realistic we used EAM [3] potentials in simulations of Pd/Cu and Cu/Pd systems. We show that the dislocations nucleate more easily in compressive than tensile strained films, and in fcc(111) orientation rather than in fcc(100). These findings are in agreement with recent experimental and theoretical works. 1. H. Jonsson, G. Mills and K. W. Jacobsen, in Classical and Quantum Dynamics in Condensed Phase Simulations, ed. by B. J. Berne, G. Ciccotti, and D. F. Coker (World Scientific, Singapore, 1998). 2. L. J. Munro and D. J. Wales, Phys. Rev. B v59, 3969 (1999), and references therein. 3. S. M. Foiles, M. I. Baskes, and M. S. Daw, Phys. Rev. B v33, 7983 (1986).

  5. Closed Talar Dislocation without Associated Fracture a Very Rare Injury, a Case Report

    PubMed Central

    Kumar, Yashavntha C; Reddy, Sandeep; Golla, Dinesh Kumar; Ganesh, Niranthara

    2014-01-01

    Introduction: Total talar dislocations are uncommon injuries and usually seen following high velocity injuries. Total talar dislocations (missing talus) without fractures around the ankle are extremely rare. There are no consensuses on the best treatment of such injuries. To best of our knowledge very few cases have been reported in literature. We hereby report a closed total talar dislocation in a 25 year old male without an associated fracture around ankle. He was managed with emergency closed reduction and below knee splint. At one year follow up there were no complications. Case Report: A 25 year old male presented to orthopaedic causality with injury to right ankle following a road traffic accident. Patient complained of severe pain and deformity of ankle following injury. On examination ankle was deformed and swollen. Plain radiographs of right ankle joint revealed total anterolateral dislocation of talus without any accompanying ankle fracture. CT scan with 3D reconstruction also confirmed our radiographic findings. Under spinal anaesthesia and fluoroscopic guidance closed reduction was performed. To maintain reduction a 3mm K-wire was passed from calcaneum to tibia through talus. A posterior below knee splint was applied. Patient was followed every three months till one year. At one year follow up patient had good range of motion at ankle and subtalar joint. Conclusion: Total talar dislocations are very rare injuries and should be treated as impending open fractures. There is no consensus on treatment of such complex injuries as very few cases have been reported in literature. PMID:27298950

  6. Visualization of dislocation dynamics in colloidal crystals.

    PubMed

    Schall, Peter; Cohen, Itai; Weitz, David A; Spaepen, Frans

    2004-09-24

    The dominant mechanism for creating large irreversible strain in atomic crystals is the motion of dislocations, a class of line defects in the crystalline lattice. Here we show that the motion of dislocations can also be observed in strained colloidal crystals, allowing detailed investigation of their topology and propagation. We describe a laser diffraction microscopy setup used to study the growth and structure of misfit dislocations in colloidal crystalline films. Complementary microscopic information at the single-particle level is obtained with a laser scanning confocal microscope. The combination of these two techniques enables us to study dislocations over a range of length scales, allowing us to determine important parameters of misfit dislocations such as critical film thickness, dislocation density, Burgers vector, and lattice resistance to dislocation motion. We identify the observed dislocations as Shockley partials that bound stacking faults of vanishing energy. Remarkably, we find that even on the scale of a few lattice vectors, the dislocation behavior is well described by the continuum approach commonly used to describe dislocations in atomic crystals. PMID:15448265

  7. 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.

  8. [Nonarthroplasty methods for developmental dysplasia of the hip with complete dislocation at the age of 8-25 patients].

    PubMed

    Zang, Jiancheng; Zhang, Hong

    2015-06-01

    It is a tough challenge treatment of complete dislocation from developmental dysplasia of the hip at the age of 8-25 patients. Although the procedure of total hip arthroplasty (THA) can improve joint function significantly, the failure rate still remains high. Hip arthrodesis remains a sensible and safe option. A stable and painless hip joint can be obtained without multiple operations. Ganz et al.had described a modified Colonna capsular arthroplasty and surgical hip dislocation with well joint functions, radiographic findings and the less complications of the femoral head osteonecrosis. There is a obvious advantage in postponing THA, and subsequent THA could be technically easier and safer in a dislocated hip. The procedure of pelvic support osteotomy, which is proposed by Ilizarov, combined two steps of femur osteotomy and femur lengthening, provides an effective treatment option for adolescent hip dysplasia or dislocation. By this procedure, the hip could be reserved, the limb length recovered and the gait improved significantly. Resection arthroplasty is a reliable method, by which 90% dysplasia patients received a painless joint and good functional outcomes. In view of certain drawbacks, it is used only as a salvage operation currently. This article reviews some alternative nonarthroplasty methods for developmental dysplasia of the hip with complete dislocation. Good clinical results can be obtained through strict indications and nice surgical skills. PMID:26359064

  9. An analysis of acromioclavicular joint morphology as a factor for shoulder impingement syndrome

    PubMed Central

    Tavakkolizadeh, Adel; Sinha, Joydeep

    2014-01-01

    Background The present study aimed to determine whether acromioclavicular (AC) joint morphology was a factor in the development of symptomatic impingement necessitating AC joint excision. Methods We performed a prospective cohort study on all patients undergoing AC joint excision for symptomatic joint pain unresponsive to conservative treatment between 2009 and 2011. This involved 106 consecutive patients (57 women, 49 men, average age 54 years, age range 33 to 76 years). Prior to surgery, radiographic classification of the AC joint was performed producing three main groups: oblique, flat or curved. Pre- and postoperative assessment was performed using the Oxford Shoulder Score and the Disabilities of the Arm, Shoulder and Hand questionnaire. Results A significantly (p < 0.05) higher frequency of oblique AC joint morphology was seen in the AC joint excision study population compared to the normal population. Postoperative outcome demonstrated no significant difference (P > 0.05) between any of the three AC joint morphologies. Conclusions The present study demonstrates a significant association between the oblique AC joint morphology and those patients who develop AC joint pain requiring surgery. Outcomes of surgery were independent of joint morphology, gender or age, with all patient subgroups demonstrating significant improvement by the end of the study.

  10. Kinetics of a Fast Moving Partial Dislocation

    NASA Astrophysics Data System (ADS)

    Daphalapurkar, Nitin; Ramesh, K. T.

    2013-03-01

    Plastic deformation in materials under extreme stresses requires a kinetic description of moving dislocations. The velocities with which the partial dislocations can propagate under an applied stress has implications for plasticity at high strain rates, specifically, the rate of plastic deformation and the rate-sensitivity. In this work, we focus our attention on motion of a twinning partial dislocation in a face-centered cubic (FCC) material, Ni. We use molecular dynamics simulations to simulate the velocity of a propagating twinning partial dislocation and investigate the effect of applied shear stress. Results suggest a limiting value for the speeds of a propagating partial dislocation. The material speeds based on the nonlinear part (under high stresses) of the stress-strain curve are shown to have an influence on the velocity with which a partial dislocation can propagate. Predicted velocities from simulations will be related to observations from high rate impact experiments. Supported by Hopkins Extreme Materials Institute

  11. Coupled dislocation and martensitic phase transformation dynamics

    NASA Astrophysics Data System (ADS)

    Barros, Kipton; Acharya, Amit; Lookman, Turab

    2013-03-01

    We present a field theoretic model that couples dislocation dynamics and plasticity with martensitic phase transformation. Dislocations produce long-range stress via incompatibility of the elastic-distortion field. Phase transformations are modeled with a non-convex elastic potential that contains the crystal symmetries of austenite and martensite phases. We discuss the effects of dislocation dynamics on material microstructure produced under extreme conditions.

  12. Robust atomistic calculation of dislocation line tension

    NASA Astrophysics Data System (ADS)

    Szajewski, B. A.; Pavia, F.; Curtin, W. A.

    2015-12-01

    The line tension Γ of a dislocation is an important and fundamental property ubiquitous to continuum scale models of metal plasticity. However, the precise value of Γ in a given material has proven difficult to assess, with literature values encompassing a wide range. Here results from a multiscale simulation and robust analysis of the dislocation line tension, for dislocation bow-out between pinning points, are presented for two widely-used interatomic potentials for Al. A central part of the analysis involves an effective Peierls stress applicable to curved dislocation structures that markedly differs from that of perfectly straight dislocations but is required to describe the bow-out both in loading and unloading. The line tensions for the two interatomic potentials are similar and provide robust numerical values for Al. Most importantly, the atomic results show notable differences with singular anisotropic elastic dislocation theory in that (i) the coefficient of the \\text{ln}(L) scaling with dislocation length L differs and (ii) the ratio of screw to edge line tension is smaller than predicted by anisotropic elasticity. These differences are attributed to local dislocation core interactions that remain beyond the scope of elasticity theory. The many differing literature values for Γ are attributed to various approximations and inaccuracies in previous approaches. The results here indicate that continuum line dislocation models, based on elasticity theory and various core-cut-off assumptions, may be fundamentally unable to reproduce full atomistic results, thus hampering the detailed predictive ability of such continuum models.

  13. Dislocation-driven surface dynamics on solids.

    PubMed

    Kodambaka, S; Khare, S V; Swiech, W; Ohmori, K; Petrov, I; Greene, J E

    2004-05-01

    Dislocations are line defects that bound plastically deformed regions in crystalline solids. Dislocations terminating on the surface of materials can strongly influence nanostructural and interfacial stability, mechanical properties, chemical reactions, transport phenomena, and other surface processes. While most theoretical and experimental studies have focused on dislocation motion in bulk solids under applied stress and step formation due to dislocations at surfaces during crystal growth, very little is known about the effects of dislocations on surface dynamics and morphological evolution. Here we investigate the near-equilibrium dynamics of surface-terminated dislocations using low-energy electron microscopy. We observe, in real time, the thermally driven nucleation and shape-preserving growth of spiral steps rotating at constant temperature-dependent angular velocities around cores of dislocations terminating on the (111) surface of TiN in the absence of applied external stress or net mass change. We attribute this phenomenon to point-defect migration from the bulk to the surface along dislocation lines. Our results demonstrate that dislocation-mediated surface roughening can occur even in the absence of deposition or evaporation, and provide fundamental insights into mechanisms controlling nanostructural stability. PMID:15129275

  14. Arthroscopic Treatment of Traumatic Hip Dislocation.

    PubMed

    Begly, John P; Robins, Bryan; Youm, Thomas

    2016-05-01

    Traumatic hip dislocations are high-energy injuries that often result in considerable morbidity. Although appropriate management improves outcomes, associated hip pathology may complicate the recovery and lead to future disability and pain. Historically, open reduction has been the standard of care for treating hip dislocations that require surgical intervention. The use of hip arthroscopy to treat the sequelae and symptoms resulting from traumatic hip dislocations recently has increased, however. When used appropriately, hip arthroscopy is a safe, effective, and minimally invasive treatment option for intra-articular pathology secondary to traumatic hip dislocation. PMID:27007728

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

    NASA Astrophysics Data System (ADS)

    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.

  16. Elbow Dislocations: A Review Ranging from Soft Tissue Injuries to Complex Elbow Fracture Dislocations

    PubMed Central

    Zellner, Johannes; Koller, Michael; Nerlich, Michael; Lenich, Andreas

    2013-01-01

    This review on elbow dislocations describes ligament and bone injuries as well as the typical injury mechanisms and the main classifications of elbow dislocations. Current treatment concepts of simple, that is, stable, or complex unstable elbow dislocations are outlined by means of case reports. Special emphasis is put on injuries to the medial ulnar collateral ligament (MUCL) and on posttraumatic elbow stiffness. PMID:24228180

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

    PubMed

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

    2016-01-01

    The stress-driven motion of dislocations in crystalline solids, and thus the ensuing plastic deformation process, is greatly influenced by the presence or absence of various pointlike defects such as precipitates or solute atoms. These defects act as obstacles for dislocation motion and hence affect the mechanical properties of the material. Here we combine molecular dynamics studies with three-dimensional discrete dislocation dynamics simulations in order to model the interaction between different kinds of precipitates and a 1/2〈111〉{110} edge dislocation in BCC iron. We have implemented immobile spherical precipitates into the ParaDis discrete dislocation dynamics code, with the dislocations interacting with the precipitates via a Gaussian potential, generating a normal force acting on the dislocation segments. The parameters used in the discrete dislocation dynamics simulations for the precipitate potential, the dislocation mobility, shear modulus, and dislocation core energy are obtained from molecular dynamics simulations. We compare the critical stresses needed to unpin the dislocation from the precipitate in molecular dynamics and discrete dislocation dynamics simulations in order to fit the two methods together and discuss the variety of the relevant pinning and depinning mechanisms. PMID:26871192

  18. Identifying foot fractures and dislocations.

    PubMed

    Caswell, Fiona; Brown, Craig

    2014-10-01

    As the roles of emergency nurse practitioners expand, more patients with minor injuries are being managed independently by nursing staff. Injuries to the foot and ankle are common among such patients, and X-rays are frequently performed to aid their diagnoses. Some of these fractures and dislocations are subtle and difficult to identify, so practitioners must adopt a structured approach to reading X-rays. This article describes some of these injuries and offers advice, including X-ray illustrations, on how to identify them. PMID:25270819

  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. Denervation of the wrist joint.

    PubMed

    Buck-Gramcko, D

    1977-01-01

    A collective review was made of the results of denervation of the wrist joint for painful restrictiorn of motion done in 313 patients and follow-up studies on 195 (average 4.1 years, ranging from 9 months to 14 years). Complete denervation was done in only 30, partial denervation in the others being done after testing with local anesthetic blocks. Sixty-nine of the patients retained a moble wrist without pain or with slight pain with heavy work. No evidence of Charcot-like joints was seen. Poorest results followed when the operation was done for sequelae of intra-articular fracture of the radius, fracture dislocations, unstable ligamentous support, joint surface destruction, or for those required to do heavy manual labor. Arthrodesis was done secondarily in nine patients. PMID:839055

  1. 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.

  2. Dislocation-Free Czochralski Silicon Crystal Growth without the Dislocation-Elimination-Necking Process

    NASA Astrophysics Data System (ADS)

    Hoshikawa, Keigo; Huang, Xinming; Taishi, Toshinori; Kajigaya, Tomio; Iino, Takayuki

    1999-12-01

    Dislocation-free silicon crystals have been grown successfully from heavily-boron-doped silicon melts by the Czochralski method without the dislocation-elimination-necking process (Dash neck). A dislocation-free silicon seed of <001> orientation with a boron concentration of about 4×1019 atoms/cm3 was used to grow a silicon crystal with the same boron concentration. No dislocation was generated in the seed during the dipping process, and no misfit dislocation occurred in the grown crystal. These results show that shoulder and body growth can be started immediately after the seeding process.

  3. Rotational knee strain resulting in patellar dislocation. An experimental study in rabbits.

    PubMed

    Finsterbush, A

    1982-09-01

    The right lower extremities of 64 young rabbits were immobilized by a plaster spica. The animals developed a gait pattern, which included internal tibial rotation and adduction of the left (unimmobilized) tibia. Twenty-one of the animals developed medial patellar dislocation in the unimmobilized lower extremity. The mechanism of the patellar dislocation in this experimental model was possibly overstretching of the lateral colateral ligament and the lateral side of the joint capsule, associated with medial rotation of the tibia and the tibial tubercle. The direction of patellar pull when gliding inferiorly during knee flexion was shifted medially, resulting in patellar dislocation and secondarily, in formation of an exostosis under the displaced patella. Hip arthrodesis in humans, as a course of rotational instability of the contralateral knee, resembles some aspects of this experimental condition. PMID:7105585

  4. A rare variant of knee dislocation

    PubMed Central

    HUSSIN, P.; MAWARDI, M.; AB HALIM, A.H.

    2016-01-01

    Knee dislocation is a rare injury. It represents less than 0.2% of orthopaedic injuries. This case reports a rare form of knee dislocation caused by the impact of a high-energy trauma. In these cases the appropriate assessment and management is needed to ensure that patient receives the proper treatment. PMID:27381692

  5. 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.

  6. Intermittent dislocation flow in viscoplastic deformation.

    PubMed

    Miguel, M C; Vespignani, A; Zapperi, S; Weiss, J; Grasso, J R

    2001-04-01

    The viscoplastic deformation (creep) of crystalline materials under constant stress involves the motion of a large number of interacting dislocations. Analytical methods and sophisticated 'dislocation dynamics' simulations have proved very effective in the study of dislocation patterning, and have led to macroscopic constitutive laws of plastic deformation. Yet, a statistical analysis of the dynamics of an assembly of interacting dislocations has not hitherto been performed. Here we report acoustic emission measurements on stressed ice single crystals, the results of which indicate that dislocations move in a scale-free intermittent fashion. This result is confirmed by numerical simulations of a model of interacting dislocations that successfully reproduces the main features of the experiment. We find that dislocations generate a slowly evolving configuration landscape which coexists with rapid collective rearrangements. These rearrangements involve a comparatively small fraction of the dislocations and lead to an intermittent behaviour of the net plastic response. This basic dynamical picture appears to be a generic feature in the deformation of many other materials. Moreover, it should provide a framework for discussing fundamental aspects of plasticity that goes beyond standard mean-field approaches that see plastic deformation as a smooth laminar flow. PMID:11287948

  7. Microscopically derived free energy of dislocations

    NASA Astrophysics Data System (ADS)

    Kooiman, M.; Hütter, M.; Geers, M. G. D.

    2015-05-01

    The dynamics of large amounts of dislocations is the governing mechanism in metal plasticity. The free energy of a continuous dislocation density profile plays a crucial role in the description of the dynamics of dislocations, as free energy derivatives act as the driving forces of dislocation dynamics. In this contribution, an explicit expression for the free energy of straight and parallel dislocations with different Burgers vectors is derived. The free energy is determined using systematic coarse-graining techniques from statistical mechanics. The starting point of the derivation is the grand-canonical partition function derived in an earlier work, in which we accounted for the finite system size, discrete glide planes and multiple slip systems. In this paper, the explicit free energy functional of the dislocation density is calculated and has, to the best of our knowledge, not been derived before in the present form. The free energy consists of a mean-field elastic contribution and a local defect energy, that can be split into a statistical and a many-body contribution. These depend on the density of positive and negative dislocations on each slip system separately, instead of GND-based quantities only. Consequently, a crystal plasticity model based on the here obtained free energy, should account for both statistically stored and geometrically necessary dislocations.

  8. Community College Adjustment among Dislocated Workers

    ERIC Educational Resources Information Center

    Schwitzer, Alan M.; Duggan, Molly H.; Laughlin, Janet T.; Walker, Martha A.

    2011-01-01

    Community colleges often are catalysts for economic and workforce development in localities with high unemployment or large numbers of dislocated workers. Increasingly, dislocated workers--individuals who have experienced job loss due to occupational closings, reduced workforces, or severe local economic downturns--are enrolling in educational and…

  9. Geometric approach to dislocation and disclination theory

    SciTech Connect

    Nesterov, A.I.; Ovchinnikov, S.G.

    1988-05-01

    Cartan structure equations are used to create a four-dimensional geometric description of dislocations in continuum theory. It is shown that the dislocation distribution is determined by the torsion tensor, while the disclination distribution is determined by the curvature tensor. An analogy to electrodynamics is offered.

  10. 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.

  11. Statistics of dislocation pinning at localized obstacles

    NASA Astrophysics Data System (ADS)

    Dutta, A.; Bhattacharya, M.; Barat, P.

    2014-10-01

    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.

  12. The neuropathic joint.

    PubMed

    Sequeira, W

    1994-01-01

    Neuropathic arthritis is a destructive arthropathy frequently associated with loss of proprioception. A third of patients, however, may have no demonstrable neurological deficit. Patients with diabetes, syphilis, syringomyelia and other neuropathies are particularly prone to developing this joint disease. The diagnosis of Charcot's joints should be considered in anyone who develops what appears to be a severe osteoarthritis or a transverse fracture of the tibia or fibula after minor trauma. Scoliosis with particularly destructive changes on radiography should prompt a search for syringomyelia or syphilis. The most common radiographic abnormalities are those of distension in 3D (Dislocation, Destruction and Degeneration). An atrophic form with resorption of the proximal humerus, most frequently described in syringomyelia, has been observed in diabetes. Loss of the distal end of the clavicle has not been described before in the neuropathies. These changes coupled with speckled calcification or shards of bone in the periarticular soft tissue confirm the diagnosis. Infection and CPPD crystal disease can be difficult to exclude. The joint fluid may be inflammatory and infection may be a complication. Treatment includes anti-inflammatories and splinting. Indications for surgery are limited. PMID:8070170

  13. Dislocation patterning in a two-dimensional continuum theory of dislocations

    NASA Astrophysics Data System (ADS)

    Groma, István; Zaiser, Michael; Ispánovity, Péter Dusán

    2016-06-01

    Understanding the spontaneous emergence of dislocation patterns during plastic deformation is a long standing challenge in dislocation theory. During the past decades several phenomenological continuum models of dislocation patterning were proposed, but few of them (if any) are derived from microscopic considerations through systematic and controlled averaging procedures. In this paper we present a two-dimensional continuum theory that is obtained by systematic averaging of the equations of motion of discrete dislocations. It is shown that in the evolution equations of the dislocation densities diffusionlike terms neglected in earlier considerations play a crucial role in the length scale selection of the dislocation density fluctuations. It is also shown that the formulated continuum theory can be derived from an averaged energy functional using the framework of phase field theories. However, in order to account for the flow stress one has in that case to introduce a nontrivial dislocation mobility function, which proves to be crucial for the instability leading to patterning.

  14. Dislocation core in GaN

    SciTech Connect

    Liliental-Weber, Zuzanna; Jasinski, Jacek B.; Washburn, Jack; O'Keefe, Michael A.

    2002-02-20

    Light emitting diodes and blue laser diodes grown on GaN have been demonstrated despite six orders of magnitude higher dislocation density than that for III-V arsenide and phosphide diodes. Understanding and determination of dislocation cores in GaN is crucial since both theoretical and experimental work are somewhat contradictory. Transmission Electron Microscopy (TEM) has been applied to study the layers grown by hydride vapor-phase epitaxy (HVPE) and molecular beam epitaxy (MBE) (under Ga rich conditions) in plan-view and cross-section samples. This study suggests that despite the fact that voids are formed along the dislocation line in HVPE material, the dislocations have closed cores. Similar results of closed core are obtained for the screw dislocation in the MBE material, confirming earlier studies.

  15. BILATERAL ANTERIOR GLENOHUMERAL DISLOCATION: CLINICAL CASE

    PubMed Central

    Silva, Luís Pires; Sousa, Cristina Varino; Rodrigues, Elisa; Alpoim, Bruno; Leal, Miguel

    2015-01-01

    Bilateral anterior glenohumeral dislocation is a rare occurrence. We present a case of bilateral anterior glenohumeral dislocation caused by a fall. The interest in publishing this case is that this is a clinical rarity with few cases reported in the literature. An 89-year-old female patient was brought to the emergency department after a fall, complaining of intense pain in both shoulders and inability to move them. Objective examination showed clinical signs giving the suspicion of bilateral anterior glenohumeral dislocation, which was confirmed by x-ray imaging. Both dislocations were successfully reduced in the emergency department using the modified Milch technique. When a synchronous and symmetrical force has acted on both shoulders and these are painful with significant functional limitation, the suspicion of bilateral glenohumeral dislocation is a differential diagnosis to be considered, even though it is rare. PMID:27047826

  16. Distribution of dislocations in nanostructured bainite

    SciTech Connect

    Cornide, J; Miyamoto, G; Caballero, Francesca G.; Furuhara, T; Miller, Michael K; Garcia-Mateo, C.

    2011-01-01

    The dislocation density in ferrite and austenite of a bainitic microstructure obtained by transformation at very low temperature (300 C) has been determined using transmission electron microscopy. Observations revealed that bainitic ferrite plates consist of two distinctive regions with different substructures. A central region in the ferrite plate is observed with dislocations that may result from lattice-invariant deformation at the earlier stage of bainite growth. As plastic deformation occurs in the surrounding austenite to accommodate the transformation strain as growth progresses, the Ferrite/Austenite interface has also a very distinctive dislocation profile. In addition, atom-probe tomography suggested that dislocation tangles observed in the vicinity of the ferrite/austenite interface might trap higher amount of carbon than single dislocations inside the bainitic ferrite plate.

  17. Arthroscopic Treatment of Perilunate Dislocations and Fracture Dislocations

    PubMed Central

    Kim, Jong Pil; Lee, Jae Sung; Park, Min Jong

    2015-01-01

    Background The key to a successful result in the treatment of perilunate dislocations (PLDs) and fracture-dislocations (PLFDs) is the restoration of normal alignment of the carpal bones, followed by stable maintenance until healing. This article aimed to assess whether arthroscopic techniques are a reliable surgical option for the treatment of this challenging injury. Materials and Methods Twenty patients with an acute PLD or PLFD were treated by an arthroscopic technique. They were retrospectively reviewed at an average follow-up of 31.2 months (range 18–61 months). Functional outcomes were assessed with the Modified Mayo Wrist Score (MMWS), Disabilities of the Arm, Shoulder, and Hand (DASH) questionnaire, and Patient-Rated Wrist Evaluation (PRWE) score as well as radiographic evaluations. Description of Technique Arthroscopic reduction and percutaneous fixation was performed to the scapholunate and lunotriquetral intervals using Kirschner wires (K-wires) as joysticks as well as to the scaphoid using a cannulated headless screw for transscaphoid-type injuries. The K-wires were removed at 10 weeks postoperation. Results Overall functional outcomes according to the MMWS were rated as excellent in three patients, good in eight, fair in seven, and poor in two. The mean DASH score was 18, and the mean PRWE score was 30. On the basis of radiographic parameters, reduction obtained at the operation was maintained within normal ranges in 15 patients. No patient had developed arthritis by the last follow-up. Conclusions The medium-term results show that arthroscopic treatment can provide proper restoration and stable fixation of carpal alignment and results in satisfactory functional and radiologic outcomes for acute perilunate injuries. Level of Evidence Level IV. PMID:25945291

  18. ACS Quicklook PDF products

    NASA Astrophysics Data System (ADS)

    Suchkov, Anatoly

    1999-12-01

    This report details the features of the ACS quicklook PDF products produced by the HST data pipeline. The requirements closely follow the design of paper products recommended by the Data Quality Committee, with appropriate changes required to fully support ACS.

  19. 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, ...

  20. Percutaneous pinning of fifth carpal-metacarpal fracture-dislocations: an alternative pin trajectory.

    PubMed

    Saing, Minn H; Lee, Sue Y; Raphael, James S

    2008-09-01

    Traditional management of unstable fourth and fifth carpal-metacarpal (CMC) fracture-dislocations (fx-dislocs) of the hand includes closed reduction and percutaneous pinning (CRPP) versus open reduction internal fixation (ORIF). Traditional trajectory of pin placement is toward the base of the hook of the hamate. Our case series of CMC fx-dislocs treated with this trajectory led to the development of ulnar deep motor branch symptoms (sxs). We attempt to propose an alternative trajectory that could lower the chance of iatrogenic injury. Five fresh frozen cadaveric specimens underwent percutaneous pinning of the fifth CMC joint using fluoroscopic guidance. Each cadaver was dissected, and the proximity of the deep motor branch of the ulnar nerve was measured in relation to a pin that penetrated the volar cortex. Our results confirm the close proximity of the deep motor branch of the ulnar nerve to the volar cortex of the hamate and demonstrate the potential for iatrogenic injury during CRPP of the fifth CMC fx-dislocs, especially with penetration of the volar cortex. By demonstrating the close proximity of the deep motor branch to the volar cortex of the hamate in cadavers, we highlight the potential for iatrogenic injury with CRPP of CMC fx-dislocs as seen in our case series. We recommend a more midaxial starting point on the proximal metacarpal with a trajectory aimed at the midbody of the hamate to prevent penetration of the hamate volar cortex and limit the chances of iatrogenic injury. PMID:18780105

  1. Percutaneous Pinning of Fifth Carpal–Metacarpal Fracture–Dislocations: An Alternative Pin Trajectory

    PubMed Central

    Lee, Sue Y.; Raphael, James S.

    2008-01-01

    Traditional management of unstable fourth and fifth carpal–metacarpal (CMC) fracture–dislocations (fx–dislocs) of the hand includes closed reduction and percutaneous pinning (CRPP) versus open reduction internal fixation (ORIF). Traditional trajectory of pin placement is toward the base of the hook of the hamate. Our case series of CMC fx–dislocs treated with this trajectory led to the development of ulnar deep motor branch symptoms (sxs). We attempt to propose an alternative trajectory that could lower the chance of iatrogenic injury. Five fresh frozen cadaveric specimens underwent percutaneous pinning of the fifth CMC joint using fluoroscopic guidance. Each cadaver was dissected, and the proximity of the deep motor branch of the ulnar nerve was measured in relation to a pin that penetrated the volar cortex. Our results confirm the close proximity of the deep motor branch of the ulnar nerve to the volar cortex of the hamate and demonstrate the potential for iatrogenic injury during CRPP of the fifth CMC fx–dislocs, especially with penetration of the volar cortex. By demonstrating the close proximity of the deep motor branch to the volar cortex of the hamate in cadavers, we highlight the potential for iatrogenic injury with CRPP of CMC fx–dislocs as seen in our case series. We recommend a more midaxial starting point on the proximal metacarpal with a trajectory aimed at the midbody of the hamate to prevent penetration of the hamate volar cortex and limit the chances of iatrogenic injury. PMID:18780105

  2. A new autoreduction method for anterior shoulder dislocation: the GONAIS method.

    PubMed

    Gonai, Shiro; Kamio, Yoshito; Matsuoka, Tomoyuki; Harunari, Manabu; Saito, Yutaka; Takuma, Kiyotsugu

    2016-01-01

    Although techniques for autoreduction of anterior shoulder dislocation have been developed, no reports have detailed an autoreduction method using the zero position and traction on the affected arm. Therefore, we developed a new autoreduction technique using the zero position and gentle autotraction. The objective of this study is to present our experience with a new method for autoreduction of anterior shoulder dislocation called the GONAIS (a backronym for “Grasp a waist-high object, Opposite arm assists, Nonsedated, Autoreduction/autotraction, Immobilize the grasped object, and Squatting and stooping”) method. A 41-year-old healthy woman with a history of left shoulder dislocation presented to the emergency department with left shoulder pain while attaching her seatbelt. The X-ray examination revealed subcoracoid dislocation of the left shoulder. The patient tried the GONAIS method after simple guidance and demonstration. Although she felt pain once when weakening traction, she achieved autoreduction successfully in only 2 min and 50 s. Clinical examination after autoreduction revealed normal neurovascular findings and appearance of the shoulder. The X-ray revealed glenohumeral joint reduction and no fracture. Here, our patient using the GONAIS method achieved shoulder autoreduction in a short time. The GONAIS method does not require lying down or sitting on the ground, does not necessarily require the opposite arm, and is minimally invasive. This method would likely be helpful for those who cannot quickly reach a hospital for treatment of anterior shoulder dislocation. PMID:26168697

  3. Recurrent Dislocation of the Patella

    PubMed Central

    Benítez, Gustavo

    2015-01-01

    Purpose: To evaluate results of medial patellofemoral ligament (MPFL) reconstruction associated with lateral release and advancement of vastus medialis in recurrent dislocation of the patella. Methods: We retrospectively evaluated 11 patients with a mean follow-up of 19 months. Mean age was 23, mainly women. We did MPFL reconstruction with semitendinosus or gracilis tendon depending on BMI, associated with advancement of vastus medialis and lateral release. Results: Mean Kujala score improved from 46,54 pts. preoperative to 88,36 postoperative. Our main complication was 1 patient with rigid knee, who required movilization under anesthesia and arthroscopic arthrolisis to improve her outcome. Conclusion: The combination of this techniques are a good alternative to treat patients with recurrent patella disclocation, with good short and mid-term results. Biomechanic intra and postop complications of MPFL reconstruction are related to patellar fixation, anatomic positioning of femoral tunnel and knee position of the graft fixation.

  4. Capsule repair may reduce dislocation following hip hemiarthroplasty through a direct lateral approach: a cadaver study.

    PubMed

    Hughes, A W; Clark, D; Carlino, W; Gosling, O; Spencer, R F

    2015-01-01

    Reported rates of dislocation in hip hemiarthroplasty (HA) for the treatment of intra-capsular fractures of the hip, range between 1% and 10%. HA is frequently performed through a direct lateral surgical approach. The aim of this study is to determine the contribution of the anterior capsule to the stability of a cemented HA through a direct lateral approach. A total of five whole-body cadavers were thawed at room temperature, providing ten hip joints for investigation. A Thompson HA was cemented in place via a direct lateral approach. The cadavers were then positioned supine, both knee joints were disarticulated and a digital torque wrench was attached to the femur using a circular frame with three half pins. The wrench applied an external rotation force with the hip in extension to allow the hip to dislocate anteriorly. Each hip was dislocated twice; once with a capsular repair and once without repairing the capsule. Stratified sampling ensured the order in which this was performed was alternated for the paired hips on each cadaver. Comparing peak torque force in hips with the capsule repaired and peak torque force in hips without repair of the capsule, revealed a significant difference between the 'capsule repaired' (mean 22.96 Nm, standard deviation (sd) 4.61) and the 'capsule not repaired' group (mean 5.6 Nm, sd 2.81) (p < 0.001). Capsular repair may help reduce the risk of hip dislocation following HA. PMID:25568428

  5. Dislocation Creep in Magnesium Calcite

    NASA Astrophysics Data System (ADS)

    Xu, L.; Xiao, X.; Evans, B. J.

    2003-12-01

    To investigate the effect of dissolved Mg on plastic deformation of calcite, we performed triaxial deformation experiments on synthetic calcite with varying amount of Mg content. Mixtures of powders of calcite and dolomite were isostatically hot pressed (HIP) at 850° C and 300 MPa confining pressure for different intervals (2 to 20hrs) resulting in homogeneous aggregates of high-magnesium calcite; Mg content varied from 0.07 to 0.17 mol%. Creep tests were performed at differential stresses from 20 to 160 MPa at 700 to 800° C. Grain sizes before and after deformation were determined from the images obtained from scanning electron microscope (SEM) and optical microscope. Grain sizes are in the range of 5 to 20 microns depending on the HIP time, and decrease with increasing magnesium content. Both BSE images and chemical analysis suggest that all dolomite are dissolved and the Mg distribution is homogeneous through the sample, after 2 hrs HIP. At stresses below 40 MPa, the samples deformed in diffusion region (Coble creep), as described previously by Herwegh. The strength decreases with increasing magnesium content, owing to the difference of grain size. At stresses above 80 MPa, the stress exponent is greater than 3, indicating an increased contribution of dislocation creep. The transition between diffusion to dislocation creep occurs at higher stresses for the samples with higher magnesium content and smaller grain size. Preliminary data suggests a slight increase in strength with increasing magnesium content, but more tests are needed to verify this effect. In a few samples, some strain weakening may have been evident. The activation energy in the transition region (at 80 MPa) is ˜200 KJ/mol with no dependence on magnesium content, agreeing with previous measurements of diffusion creep in natural and synthetic marbles.

  6. Distal Clavicle Osteolysis after Modified Weaver-Dunn's Procedure for Chronic Acromioclavicular Dislocation: A Case Report and Review of Complications

    PubMed Central

    Santana, Fernando; Mingo, Felipe; Piñol, Ignasi; Solano, Albert; Puig-Verdié, Lluís; Torrens, Carles

    2014-01-01

    Distal clavicle osteolysis after acromioclavicular joint stabilization has only been described after the use of hardware for clavicle stabilization or synthetic graft causing a foreign body reaction. This paper reports a very rare case of distal clavicle osteolysis after modified Weaver-Dunn procedure for the treatment of chronic acromioclavicular joint dislocation. The paper also provides a comprehensive review of complications of this surgical technique and discusses a potential vascular etiology and preventive strategies aimed at avoiding clavicle osteolysis. PMID:25544923

  7. Continuum framework for dislocation structure, energy and dynamics of dislocation arrays and low angle grain boundaries

    NASA Astrophysics Data System (ADS)

    Zhu, Xiaohong; Xiang, Yang

    2014-09-01

    We present a continuum framework for dislocation structure, energy and dynamics of dislocation arrays and low angle grain boundaries that are allowed to be nonplanar or nonequilibrium. In our continuum framework, we define a dislocation density potential function on the dislocation array surface or grain boundary to describe the orientation dependent continuous distribution of dislocations in a very simple and accurate way. The continuum formulations incorporate both the long-range dislocation interaction and the local dislocation line energy, and are derived from the discrete dislocation model. The continuum framework recovers the classical Read-Shockley energy formula when the long-range elastic fields of the low angle grain boundaries are canceled out. Applications of our continuum framework in this paper are focused on dislocation structures on static planar and nonplanar low angle grain boundaries and misfitting interfaces. We present two methods under our continuum framework for this purpose, including the method based on the Franks formula and the energy minimization method. We show that for any (planar or nonplanar) low angle grain boundary, the Franks formula holds if and only if the long-range stress field in the continuum model is canceled out, and it does not necessarily hold for a total energy minimum dislocation structure.

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

    SciTech Connect

    Qian Chen

    2008-08-18

    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.

  9. 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.

  10. Ipsilateral Traumatic Posterior Hip Dislocation, Posterior Wall and Transverse Acetabular Fracture with Trochanteric Fracture in an adult: Report of First Case

    PubMed Central

    Sinha, Skand; Naik, Ananta k; Arya, Rajendra K; Jain, Vijay K

    2013-01-01

    Introduction: Posterior dislocation of the hip joint with associated acetabular and intertrochanteric fracture is a complex injury. Early recognition, prompt and stable reduction is needed of successful outcome. Case Report: 45 year old male patient presented with posterior dislocation of the hip with transverse fracture with posterior wall fracture of acetabulam and intertrochanteric fracture on the ipsilateral side. The complex fracture geometry was confirmed by CT scan. The patient was successfully managed by open reduction and internal fixation of intertrochanteric fracture was achieved with dynamic hip screw (DHS) plate fixation followed by fixation of acetabular fracture with reconstruction plate. Conclusion: Hip dislocation combined with acetabular fracture is an uncommon injury; this article presents a unique case of posterior wall and transverse fractures of ipsilateral acetabulum with intertrochanteric fracture in a patient who sustained traumatic posterior hip dislocation. Early surgical intervention is important for satisfactory outcomes of such complex fracture-dislocation injuries. PMID:27298928

  11. 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.

  12. Ultrasonic Study of Dislocation Dynamics in Lithium -

    NASA Astrophysics Data System (ADS)

    Han, Myeong-Deok

    1987-09-01

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

  13. [Preliminary treatment of congenital hip dislocation using physical therapy based on neurophysiology].

    PubMed

    Niethard, F U

    1987-01-01

    Adductor tightness is a typical symptom in CDH. In cases of subluxation and complete dislocation even a rigid abduction contracture can occur, preventing reduction and favouring redislocation. The contracture of the hip joint is the result of neurophysiological disorders, which can be treated by an exercise program on a neurophysiological basis. 62 children with 73 severely contracted and 5 hypotonic hip dislocations have been treated by the so-called "Vojta-program" before reduction. In a prospective study over 5 years this kind of treatment has been very successful: the incidence of necrosis of the femoral head could be reduced to 4%, long-lasting traction was not necessary anymore and the rigid hip joints required open reduction only in 2 cases. PMID:3577341

  14. 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

  15. Dislocation punching from ceramic/metal interfaces

    SciTech Connect

    Taya, M. ); Mori, T. . Dept. of Materials Science and Engineering)

    1994-07-01

    Relaxation of misfit strains at interfaces between two different materials by dislocation punching is studied analytically by focusing on two types of interfaces: planar and nonplanar. As an example of planar type interface, the case of metal coating/ceramic substrate system is studied while ceramic filler/metal matrix composite system is examined as an example of a nonplanar interface. Based on the present analytical model, the condition for dislocation punching for each interface is established. Validity of the dislocation punching model is verified by comparing the analytical results with limited experimental results, resulting in a good agreement.

  16. Canonical Quantization of Crystal Dislocation and Electron-Dislocation Scattering in an Isotropic Media

    NASA Astrophysics Data System (ADS)

    Li, Mingda; Cui, Wenping; Dresselhaus, M. S.; Chen, Gang; MIT Team; Boston College Team

    Crystal dislocations govern the plastic mechanical properties of materials but also affect the electrical and optical properties. However, a fundamental and decent quantum-mechanical theory of dislocation remains undiscovered for decades. Here we present an exact and manageable Hamiltonian theory for both edge and screw dislocation line in an isotropic media, where the effective Hamiltonian of a single dislocation line can be written in a harmonic-oscillator-like form, with closed-form quantized 1D phonon-like excitation. Moreover a closed-form, position dependent electron-dislocation coupling strength is obtained, from which we obtained good agreement of relaxation time when comparing with classical results. This Hamiltonian provides a platform to study the effect of dislocation to materials' non-mechanical properties from a fundamental Hamiltonian level.

  17. 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.

  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. Model for dislocation locking by oxygen gettering in silicon crystals

    NASA Astrophysics Data System (ADS)

    Maroudas, Dimitris; Brown, Robert A.

    1991-04-01

    Oxygen gettering to dislocations slows and stops dislocation motion caused by applied stress in silicon crystals. A model is presented that quantitatively describes the inhibition of dislocation motion by accounting for the drag caused by the oxygen atmosphere in the crystal around the dislocation and for oxygen aggregates inside the dislocation core. The oxygen distribution is computed by analysis of diffusion and stress-assisted migration in the crystalline lattice. The predictions of the model agree quantitatively with the experimental data of Imai and Sumino. Hysteresis is predicted in the dependence of the dislocation velocity on applied stress and explains the difference in the unlocking and locking stresses for dislocation motion.

  20. Automated identification and indexing of dislocations in crystal interfaces

    DOE PAGESBeta

    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

  1. 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. PMID:19292189

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

    NASA Astrophysics Data System (ADS)

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

    2014-06-01

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

  3. Energy and entropy of interacting dislocations

    SciTech Connect

    Ladd, A.J.C.; Hoover, W.G.

    1982-11-15

    The energy and entropy of interacting edge dislocations have been calculated by atomistic simulations, with the use of piecewise-linear forces in a two-dimensional triangular lattice. We conclude that the interaction energy between small groups of dislocations is well described by continuum mechanics for separations greater than a few lattice spacings. Our calculations enable us to make a precise determination of the core energy, which is an essential parameter in determining dislocation multiplication rates. We find also that continuum mechanics gives an accurate representation of the interaction of a dislocation pair with a homogeneous elastic stress field. The vibrational contribution to the entropy of such a pair is small, about 0.3k.

  4. 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

  5. Quenched pinning and collective dislocation dynamics.

    PubMed

    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

  6. Dislocation shielding of a cohesive crack

    NASA Astrophysics Data System (ADS)

    Bhandakkar, Tanmay K.; Chng, Audrey C.; Curtin, W. A.; Gao, Huajian

    2010-04-01

    Dislocation interaction with a cohesive crack is of increasing importance to computational modelling of crack nucleation/growth and related toughening mechanisms in confined structures and under cyclic fatigue conditions. Here, dislocation shielding of a Dugdale cohesive crack described by a rectangular traction-separation law is studied. The shielding is completely characterized by three non-dimensional parameters representing the effective fracture toughness, the cohesive strength, and the distance between the dislocations and the crack tip. A closed form analytical solution shows that, while the classical singular crack model predicts that a dislocation can shield or anti-shield a crack depending on the sign of its Burgers vector, at low cohesive strengths a dislocation always shields the cohesive crack irrespective of the Burgers vector. A numerical study shows the transition in shielding from the classical solution of Lin and Thomson (1986) in the high strength limit to the solution in the low strength limit. An asymptotic analysis yields an approximate analytical model for the shielding over the full range of cohesive strengths. A discrete dislocation (DD) simulation of a large (>10 3) number of edge dislocations interacting with a cohesive crack described by a trapezoidal traction-separation law confirms the transition in shielding, showing that the cohesive crack does behave like a singular crack at very high cohesive strengths (˜7 GPa), but that significant deviations in shielding between singular and cohesive crack predictions arise at cohesive strengths around 1GPa, consistent with the analytic models. Both analytical and numerical studies indicate that an appropriate crack tip model is essential for accurately quantifying dislocation shielding for cohesive strengths in the GPa range.

  7. Dislocation dynamics of web type silicon ribbon

    NASA Technical Reports Server (NTRS)

    Dillon, O. W., Jr.; Tsai, C. T.; De Angelis, R. J.

    1987-01-01

    Silicon ribbon grown by the dendritic web process passes through a rapidly changing thermal profile in the growth direction. This rapidly changing profile induces stresses which produce changes in the dislocation density in the ribbon. A viscoplastic material response function (Haasen-Sumino model) is used herein to calculate the stresses and the dislocation density at each point in the silicon ribbon. The residual stresses are also calculated.

  8. Atomistic modeling of dislocation-interface interactions

    SciTech Connect

    Wang, Jian; Valone, Steven M; Beyerlein, Irene J; Misra, Amit; Germann, T. C.

    2011-01-31

    Using atomic scale models and interface defect theory, we first classify interface structures into a few types with respect to geometrical factors, then study the interfacial shear response and further simulate the dislocation-interface interactions using molecular dynamics. The results show that the atomic scale structural characteristics of both heterophases and homophases interfaces play a crucial role in (i) their mechanical responses and (ii) the ability of incoming lattice dislocations to transmit across them.

  9. An Alternate Conservative Management of Shoulder Dislocations and Subluxations

    PubMed Central

    Sawa, Thomas M.

    1992-01-01

    This paper presents clinical observations/results of the application of an alternate method to traditional conservative management of subluxations and dislocations of the glenohumeral joint on major junior hockey players. The proposed program involves three stages: 1) rest and nutrition, 2) interferential current and faradic muscle stimulation, and 3) a traditional progressive-resistance weight-training program in conjunction with a specially designed orthosis. Current scientific theory on soft tissue healing and repair is reviewed as the backdrop to the proposed regimen. The resulting 100% success rate is compared to the success rate of conventional conservative therapeutic programs. The orthosis is a potentially useful therapeutic device permitting safe ranges of shoulder movement during the healing process, but scientific investigation is needed to determine the precise effect of the orthosis within the proposed therapy program. PMID:16558196

  10. 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.

  11. 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

  12. Dislocation electrical conductivity of synthetic diamond films

    SciTech Connect

    Samsonenko, S. N. Samsonenko, N. D.

    2009-05-15

    A relationship between the electric resistance of single-crystal homoepitaxial and polycrystalline diamond films and their internal structure has been investigated. It is established that the electrical conductivity of undoped homoepitaxial and polycrystalline diamond films is directly related to the dislocation density in them. A relation linking the resistivity {rho} ({approx}10{sup 13}-10{sup 15} {omega} cm) with the dislocation density {gamma} ({approx}10{sup 14}-4 x 10{sup 16} m{sup -2}) is obtained. The character of this correlation is similar for both groups of homoepitaxial and polycrystalline diamond films. Thin ({approx}1-8 {mu}m) homoepitaxial and polycrystalline diamond films with small-angle dislocation boundaries between mosaic blocks exhibit dislocation conductivity. The activation energy of dislocation acceptor centers was calculated from the temperature dependence of the conductivity and was found to be {approx}0.3 eV. The conduction of thick diamond films (h > 10 {mu}m) with the resistivity {rho} {approx} 10{sup 8} {omega} cm is determined by the conduction of intercrystallite boundaries, which have a nondiamond hydrogenated structure. The electronic properties of the diamond films are compared with those of natural semiconductor diamonds of types IIb and Ic, in which dislocation acceptor centers have activation energies in the range 0.2-0.35 eV and are responsible for hole conduction.

  13. Dislocation motion in solid hcp 3He

    NASA Astrophysics Data System (ADS)

    Beamish, John; Cheng, Zhi Gang

    At temperatures above about 100 mK, dislocations reduce the shear modulus of hcp 4He by as much as 90 %. This occurs when dislocations thermally unbind from the 3He impurities that pin them, becoming extraordinarily mobile. The elastic softening is accompanied by a thermally activated dissipation peak due to the 3He impurities. At higher temperatures the dissipation has an ωT4 dependence caused by scattering of thermal phonons from moving dislocations. Previous measurements on the fermi solid, hcp 3He, showed a similar dislocation softening, but the corresponding dissipation was not measured. We have extended these measurements by measuring the temperature, amplitude and frequency dependence of both the shear modulus and the dissipation in hcp 3He. The dissipation behavior is very different from that of hcp 4He. Neither the impurity unbinding peak associated with the elastic softening, nor the high temperature phonon scattering dissipation, were observed. Instead, there is a large and non-thermally activated dissipation which is largest at low frequencies. We believe that this unexpected dissipation is associated with a new dislocation damping mechanism in 3He, perhaps associated with spin rearrangements caused by moving dislocations. This work was supported by a grant from NSERC Canada.

  14. Isolated dorsal dislocation of the lunate.

    PubMed

    Siddiqui, Na; Sarkar, Sp

    2012-01-01

    Lunate dislocations are well described in the volar direction as part of the perilunate dislocation, sometimes together with fractures of the other carpal bones or distal radius, as described by the anatomical studies of Mayfield [1]. It is a result of disruption of the complex inter-carpal and radiocarpal ligaments that hold the well conforming carpus in their normal position. Given the strength of these structures a significant trauma is required to cause them to fail.However, we present a case of a patient who not only presented with relatively trivial trauma that resulted in a lunate dislocation, but it was also in the dorsal direction and not associated with any fracture or neurological compromise. In addition, she presented several days after her injury.We treated her with closed manipulation and percutaneous K-wire fixation followed by a short period of immobilisation in a Plaster-of-Paris cast, with rapid return to full duties at work.As many volar lunate dislocations may be missed at presentation, we suggest that in patients with relatively trivial trauma there should also be a suspicion of the lunate dislocating dorsally, which may be treated successfully without the aggressive open surgery usually required in volar perilunate dislocations. PMID:23248723

  15. Dislocation creep of fine-grained olivine

    NASA Astrophysics Data System (ADS)

    Faul, U. H.; Fitz Gerald, J. D.; Farla, R. J. M.; Ahlefeldt, R.; Jackson, I.

    2011-01-01

    Deformation experiments conducted in a gas medium apparatus at temperatures from 1200 to 1350°C with a fine-grained, solution-gelation derived Fe-bearing olivine show a stress dependence of the strain rate at stresses above ˜150 MPa, which is much stronger than previously reported for polycrystalline samples. The data can be fit by a power law with ??σn with n ˜ 7-8, or equally well by a Peierls creep law with exponential stress dependence. Due to the observed strong stress dependence the samples deform at significantly higher strain rates at a given stress than single crystals or coarse-grained polycrystals with n ˜ 3.5. TEM observations indicate the presence of dislocations with at least two different Burgers vectors, with free dislocations predominantly of screw character. Subgrain walls are present but are only weakly developed and have small misorientation angles. Both the rheology and dislocation structures are consistent with creep rate-limited by dislocation glide or cross slip for aggregates with grain sizes smaller than or approaching the recrystallized grain size. Deformation mechanism maps extrapolated to lithospheric temperatures using the melt-free diffusion creep rheology of Faul and Jackson (2007), the dislocation creep rheology of Hirth and Kohlstedt (2003), and the results described here indicate that deformation conditions of ultramylonitic shear zones fall near the triple point of Peierls, dislocation, and diffusion creep.

  16. Generalized dynamics of moving dislocations in quasicrystals

    NASA Astrophysics Data System (ADS)

    Agiasofitou, Eleni; Lazar, Markus; Kirchner, Helmut

    2010-12-01

    A theoretical framework for dislocation dynamics in quasicrystals is provided according to the continuum theory of dislocations. Firstly, we present the fundamental theory for moving dislocations in quasicrystals giving the dislocation density tensors and introducing the dislocation current tensors for the phonon and phason fields, including the Bianchi identities. Next, we give the equations of motion for the incompatible elastodynamics as well as for the incompatible elasto-hydrodynamics of quasicrystals. We continue with the derivation of the balance law of pseudomomentum thereby obtaining the generalized forms of the Eshelby stress tensor, the pseudomomentum vector, the dynamical Peach-Koehler force density and the Cherepanov force density for quasicrystals. The form of the dynamical Peach-Koehler force for a straight dislocation is obtained as well. Moreover, we deduce the balance law of energy that gives rise to the generalized forms of the field intensity vector and the elastic power density of quasicrystals. The above balance laws are produced for both models. The differences between the two models and their consequences are revealed. The influences of the phason fields as well as of the dynamical terms are also discussed.

  17. Generalized dynamics of moving dislocations in quasicrystals.

    PubMed

    Agiasofitou, Eleni; Lazar, Markus; Kirchner, Helmut

    2010-12-15

    A theoretical framework for dislocation dynamics in quasicrystals is provided according to the continuum theory of dislocations. Firstly, we present the fundamental theory for moving dislocations in quasicrystals giving the dislocation density tensors and introducing the dislocation current tensors for the phonon and phason fields, including the Bianchi identities. Next, we give the equations of motion for the incompatible elastodynamics as well as for the incompatible elasto-hydrodynamics of quasicrystals. We continue with the derivation of the balance law of pseudomomentum thereby obtaining the generalized forms of the Eshelby stress tensor, the pseudomomentum vector, the dynamical Peach-Koehler force density and the Cherepanov force density for quasicrystals. The form of the dynamical Peach-Koehler force for a straight dislocation is obtained as well. Moreover, we deduce the balance law of energy that gives rise to the generalized forms of the field intensity vector and the elastic power density of quasicrystals. The above balance laws are produced for both models. The differences between the two models and their consequences are revealed. The influences of the phason fields as well as of the dynamical terms are also discussed. PMID:21406784

  18. 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. PMID:25560996

  19. 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

  20. Core structures analyses of (a+c)-edge dislocations in wurtzite GaN through atomistic simulations and Peierls–Nabarro model

    SciTech Connect

    Chen, Cheng; Meng, Fanchao; Song, Jun

    2015-05-21

    The core structures and slip characteristics of (a+c)-edge dislocations on pyramidal planes in wurtzite GaN were investigated employing molecular dynamics simulations. Multiple stable core configurations are identified for dislocations along the glide and shuffle planes. The corresponding generalized-stacking-fault energy (GSFE) curves for the glide and shuffle slips are calculated. The GSFE curves, combined with the Peierls–Nabarro model, demonstrate that the shuffle slip is favored over the glide slip given the markedly lower Peierls energy and stress of the shuffle slip. Our findings also indicate that in general slip motions for (a+c)-edge dislocations are only possible at elevated temperature, and the necessity of further studies of thermally activated processes to better understand the dynamics of (a+c) dislocations in GaN.

  1. Temporomandibular joints: high-resolution computed tomographic evaluation

    SciTech Connect

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

    1984-01-01

    High-resolution computed tomography of the temporomandibular joint (TMJ) was performed in 43 patients. Exquisite detail of the face, skull base, and TMJs was obtained with CT using soft tissue and bone algorithms, narrow collimation, and multiplanar images. In 10 patients clinically suspected of joint derangement, CT results were in close agreement with surgical findings and arthrography in 13/15 joints. CT showed indirect signs of disc dislocation, and the dislocated disc itself in 81% of affected joints. In two patients, arthrography with CT proved to be more helpful than conventional arthrography alone. CT without intra-articular contrast material provided information not appreciated on conventional radiogaphs in 28 patients (65%) and was particularly helpful in evaluating patients with disc pathosis and trauma. Early experience with CT of the TMJ shows that it is an excellent method of evaluation at acceptable radiation exposure levels that adds essential information not seen on standard radiographs.

  2. 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.

  3. Clinical results of coracoacromial ligament transfer in acromioclavicular dislocations: A review of published literature.

    PubMed

    Sood, Aman; Wallwork, Nicholas; Bain, Gregory Ian

    2008-01-01

    Acromioclavicular joint dislocations are common injuries, which typically occur with trauma in young men. Treatment recommendations for these injuries are highly variable and controversial. There are greater than 100 surgical techniques described for operative treatment of this injury. One of the most widely recommended methods of surgical reconstruction for acromioclavicular joint dislocations is to utilize the coracoacromial ligament for stabilization of the distal clavicle. Several modifications of this procedure have been described which have involved adjunct coracoclavicular fixation or fixation across acromioclavicular joint. Although the literature is replete with descriptive papers, there is paucity of studies evaluating the surgical outcome of this procedure. We systematically reviewed the English language published literature in peer reviewed journals (Medline, EMBASE, SCOPUS) and assigned a level of evidence for available studies. We critically reviewed each paper for the flaws and biases and then evaluated the comparable clinical outcomes for various procedures and their modifications. The published literature consists entirely of case series (Level IV evidence) with variability in surgical technique and outcome measures. On review there is low level evidence to support the use of coracoacromial ligament for acromioclavicular dislocation but it has been associated with high rate of deformity recurrence. Adjunct fixation does not improve clinical results when compared to isolated coracoacromial ligament transfer. This is in part because of the high incidence of fixation related complications. Similar results are reported with coracoacromial ligament reconstruction for acute and chronic cases. The development of secondary acromioclavicular joint symptoms with distal clavicle retention is poorly reported with the incidence rate varying from 12% to 32%. Despite this, the retention or excision of distal clavicle did not affect overall clinical results except

  4. A novel use for suture button suspension: reconstruction of the dorsal ulnar ligament to treat thumb metacarpal dislocation

    PubMed Central

    Shah, Ajul; Martin, Garry; Thomson, James Grant

    2015-01-01

    Abstract There are numerous treatment algorithms that have been developed to treat thumb carpometacarpal (CMC) arthritis. A newer treatment option for these patients is CMC stabilization using suture button suspensionplasty. The authors of this case report have extensive experience with the suture-button suspensionplasty using the Mini TightRope CMC technique (Arthrex). We present a novel usage of the suture-button suspensionplasty to reconstruct the dorsal ulnar ligament (in contrast to the usual reconstruction of the volar beak ligament) to treat a patient with persistent thumb metacarpal dislocation at the CMC joint. Two separate patients are presented. One patient demonstrates volar beak ligament instability, and the other demonstrates dorsal ulnar ligament instability. Both patients’ demographics and operative indications are described. The operative technique for the novel usage of the suture-button suspensionplasty is described. Operative results of the dorsal ulnar ligament reconstruction are reviewed. After suture-button suspension of the thumb metacarpal to the trapezium, the dorsal ulnar ligament has been reconstructed. The patient demonstrated stability of the thumb CMC joint without dorsal or radial dislocation. The authors of this case report present a novel usage of the suture-button suspensionplasty to treat a patient with proximal thumb metacarpal dislocation at the trapezial-metacarpal interface. This method, in contrast to the referenced method of volar beak ligament reconstruction, allows reconstruction of the dorsal ulnar ligament. This allows stabilization of the joint by preventing dorsal and radial dislocation of the metacarpal.

  5. Un trait du francais parle authentique: La dislocation. (A Trait of Authentic Spoken French: Dislocation.)

    ERIC Educational Resources Information Center

    Calve, Pierre

    1983-01-01

    The dislocation of sentence elements in spoken French is seen as allowing the speaker to free himself from certain constraints imposed on word order, position of accents, and grammar. Dislocation is described, its various functions are enumerated, and implications for second language instruction are outlined. (MSE)

  6. Utilization of the safe surgical dislocation approach of the hip to retrieve a bullet from the femoral head.

    PubMed

    Delaney, Ruth; Albright, Maurice; Rebello, Gleeson

    2011-01-01

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

  7. Advances in the theory of the Hall-Petch relation, dislocation pileups and dislocation sources

    NASA Astrophysics Data System (ADS)

    Friedman, Lawrence Henry

    Advances in the theory of dislocations are reported. The Hall-Petch relation is extended, and a continuum level simulation of curvilinear dislocations is developed and used to study the operation of Frank-Read sources. The Hall-Petch relation states that the yield stress, sigma y, or strength against plastic deformation of polycrystalline materials is enhanced by decreasing the grain diameter: sigma y = Kd--1/2 + sigma 0, with K and sigma0 constants. One explanation of this relation is that yielding results from stress concentrated by queues of dislocations known as pileups. The pileup theory of the Hall-Petch relation is extended in two ways. First, two important aspects of pileup formation are incorporated into the theory: the existence of a threshold stress for dislocation production and the necessity of a finite-sized dislocation-free region in which a dislocation source may operate. Using a continuum theory of dislocation pileups, a closed form expression is obtained for the dependence of yield stress on grain size and source characteristics. The continuum model agrees closely with the corresponding discrete dislocation model. Second, a scaling theory describing the strength of lamellar materials is developed. The Hall-Petch relation is found to result from the similarity between dislocation densities of pileups of different lengths and under different applied stresses. For multilayers, the scaling theory predicts sigma y = KΛ--a + sigma0, where Λ is the compositional wavelength of the multilayer and a is a material dependent exponent. The scaling theory is then enlarged to incorporate parameters important to the operation of dislocation sources. The simulation of curvilinear dislocations, based on linear isotropic elasticity theory, includes self stress and dislocation-dislocation interactions. The operation stress of a Frank-Read source is found as a function of source size. Additionally, the plastic strain produced by a continuously operating source was

  8. Dislocation dynamics in multiwalled carbon nanotubes at high temperatures.

    PubMed

    Huang, J Y; Ding, F; Yakobson, B I

    2008-01-25

    Dislocation dynamics dictate the mechanical behavior of materials. Dislocations in periodic crystalline materials have been well documented. On the contrary, dislocations in cylindrical carbon nanotubes, particularly in multiwalled carbon nanotubes (MWCNTs), remain almost unexplored. Here we report that a room temperature 1/2<0001> sessile dislocation in a MWCNT becomes highly mobile, as characterized by its glide, climb, and the glide-climb interactions, at temperatures of about 2000 degrees C. The dislocation glide leads to the cross-linking of different shells; dislocation climb creates nanocracks; and the interaction of two 1/2<0001> dislocations creates kinks. We found that dislocation loops act as channels for mass transport. These dislocation dynamics are drastically different from that in conventional periodic crystalline materials due to the cylindrical, highly anisotropic structures of MWCNTs. PMID:18232998

  9. Bauschinger effect in thin metal films: Discrete dislocation dynamics study

    NASA Astrophysics Data System (ADS)

    Davoudi, Kamyar M.; Nicola, Lucia; Vlassak, Joost J.

    2014-01-01

    The effects of dislocation climb on plastic deformation during loading and unloading are studied using a two-dimensional discrete dislocation dynamics model. Simulations are performed for polycrystalline thin films passivated on both surfaces. Dislocation climb lowers the overall level of the stress inside thin films and reduces the work hardening rate. Climb decreases the density of dislocations in pile-ups and reduces back stresses. These factors result in a smaller Bauschinger effect on unloading compared to simulations without climb. As dislocations continue to climb at the onset of unloading and the dislocation density continues to increase, the initial unloading slope increases with decreasing unloading rate. Because climb disperses dislocations, fewer dislocations are annihilated during unloading, leading to a higher dislocation density at the end of the unloading step.

  10. Influence of dislocation and dislocation loop biases on microstructures simulated by rate equation cluster dynamics

    NASA Astrophysics Data System (ADS)

    Jourdan, T.

    2015-12-01

    Sensitivity of microstructures under irradiation to absorption biases of dislocations and dislocation loops is investigated by rate equation cluster dynamics (RECD). Contrary to standard rate theory which is often used to estimate sensitivity of cavity growth to biases, it is possible with RECD to quantify the effect of biases on nucleation, growth and coarsening of loops and cavities. For this purpose simple and accurate expressions for dislocation and dislocation loop biases are derived, based on finite element calculations. They are used in a RECD code to quantify the effect of biases on microstructures of austenitic steels irradiated with electrons. It is shown that biases have a strong influence not only on the loop and dislocation network evolutions, but also on cavity nucleation. Sensitivity to some other parameters of the model is also discussed.

  11. Temporomandibular Joint, Closed

    MedlinePlus

    ... Oral Health > The Temporomandibular Joint, Closed The Temporomandibular Joint, Closed Main Content Title: The Temporomandibular Joint, Closed Description: The temporomandibular joint connects the lower ...

  12. Screw dislocations in GaN

    SciTech Connect

    Liliental-Weber, Zuzanna; Jasinski, Jacek B.; Washburn, Jack; O'Keefe, Michael A.

    2002-02-15

    GaN has received much attention over the past few years because of several new applications, including light emitting diodes, blue laser diodes and high-power microwave transistors. One of the biggest problems is a high density of structural defects, mostly dislocations, due to a lack of a suitable lattice-matched substrate since bulk GaN is difficult to grow in large sizes. Transmission Electron Microscopy (TEM) has been applied to study defects in plan-view and cross-sections on samples prepared by conventional techniques such as mechanical thinning and precision ion milling. The density of dislocations close to the sample surface of a 1 mm-thick HVPE sample was in the range of 3x109 cm-2. All three types of dislocations were present in these samples, and almost 50 percent were screw dislocations. Our studies suggest that the core structure of screw dislocations in the same material might differ when the material is grown by different methods.

  13. Glassy dislocation dynamics in colloidal dimer crystals

    NASA Astrophysics Data System (ADS)

    Gerbode, Sharon

    2012-02-01

    Dislocation mobility is central to both the mechanical response and the relaxation mechanisms of crystalline materials. Recent experiments have explored the role of novel particle anisotropies in affecting the rules of defect motion in crystals. ``Peanut-shaped'' colloidal dimer particles consisting of two connected spherical lobes form densely packed crystals in 2D. In these ``degenerate crystals,'' the particle lobes occupy triangular lattice sites while the particle axes are randomly oriented among the three crystalline directions. One consequence of the random orientations of the dimers is that dislocation glide is severely limited by certain particle arrangements in the degenerate crystals. Using optical tweezers to manipulate single lobe-sized spherical intruder particles, we locally deform the crystal, creating defects. During subsequent relaxation, the dislocations formed during the deformation leave the crystal grain, either via annihilation with other dislocations or by moving to a grain boundary. Interestingly, in large crystalline grains this dislocation relaxation occurs through a two-stage process reminiscent of slow relaxations in glassy systems, suggesting the novel concept that glassy phenomena may be introduced to certain kinds of colloidal crystals via simple anisotropic constituents.

  14. Isolated dorsal dislocation of the tarsal naviculum

    PubMed Central

    Hamdi, Kaziz; Hazem, Ben Ghozlen; Yadh, Zitoun; Faouzi, Abid

    2015-01-01

    Isolated dislocation of the tarsal naviculum is an unusual injury, scarcely reported in the literature. The naviculum is surrounded by the rigid bony and ligamentous support hence fracture dislocation is more common than isolated dislocation. The mechanism and treatment options remain unclear. In this case report, we describe a 31 year old man who sustained an isolated dorsal dislocation of the left tarsal naviculum, without fracture, when he was involved in a motor vehicle collision. The reported mechanism of the dislocation is a hyper plantar flexion force applied to the midfoot, resulting in a transient disruption of the ligamentous support of the naviculum bone, with dorsal displacement of the bone. The patient was treated with open reduction and Krischner-wire fixation of the navicular after the failure of closed reduction. The wires were removed after 6 weeks postoperatively. Physiotherapy for stiffness and midfoot pain was recommended for 2 months. At 6 months postoperatively, limping, midfoot pain and weakness were reported, no X-ray abnormalities were found. The patient returned to his obvious activities with a normal range of motion. PMID:26806978

  15. Dislocation dynamics in an anisotropic stripe pattern.

    PubMed

    Kamaga, Carina; Ibrahim, Fatima; Dennin, Michael

    2004-06-01

    The dynamics of dislocations confined to grain boundaries in a striped system are studied using electroconvection in the nematic liquid crystal N4. In electroconvection, a striped pattern of convection rolls forms for sufficiently high driving voltages. We consider the case of a rapid change in the voltage that takes the system from a uniform state to a state consisting of striped domains with two different wave vectors. The domains are separated by domain walls along one axis and a grain boundary of dislocations in the perpendicular direction. The pattern evolves through dislocation motion parallel to the domain walls. We report on features of the dislocation dynamics. The kinetics of the domain motion is quantified using three measures: dislocation density, average domain wall length, and total domain wall length per area. All three quantities exhibit behavior consistent with power-law evolution in time, with the defect density decaying as t(-1/3), the average domain wall length growing as t(1/3), and the total domain wall length decaying as t(-1/5). The two different exponents are indicative of the anisotropic growth of domains in the system. PMID:15244714

  16. Crack interaction with 3-D dislocation loops

    NASA Astrophysics Data System (ADS)

    Gao, Huajian

    CRACKS in a solid often interact with other crystal defects such as dislocation loops. The interaction effects are of 3-D character yet their analytical treatment has been mostly limited to the 2-D regime due to mathematical complications. This paper shows that distribution of the stress intensity factors along a crack front due to arbitrary dislocation loops may be expressed as simple line integrals along the loop contours. The method of analysis is based on the 3-D Bueckner-Rice weight function theory for elastic crack analysis. Our results have significantly simplified the calculations for 3-D dislocation loops produced in the plastic processes at the crack front due to highly concentrated crack tip stress fields. Examples for crack-tip 3-D loops and 2-D straight dislocations emerging from the crack tip are given to demonstrate applications of the derived formulae. The results are consistent with some previous analytical solutions existing in the literature. As further applications we also analyse straight dislocations that are parallel or perpendicular to the crack plane but are not parallel to the crack front.

  17. Search for dislocation free 4He crystals

    NASA Astrophysics Data System (ADS)

    Souris, Fabien; Fefferman, Andrew; Haziot, Ariel; Beamish, John; Balibar, Sebastien

    2014-03-01

    The elastic anomaly of 4He crystals is known to be a consequence of the motion of their dislocations. We have built an acoustic cell in order to grow and study crystals with the smallest possible density of dislocations. It has a polished inner surface to avoid pinning sites for the liquid-solid interface. Piezoelectric transducers are placed outside the cell volume, in order to drive and detect acoustical resonances through built-in copper membranes. We expect dislocation free crystals to behave rather differently from the usual ones (1,2). For example, they should not show any anomalous softening. Preliminary results show that crystals grown in this particular cell have longer dislocation lengths than in those studied in previous experiments (1,2). Centimeter long dislocations should resonate below 20 kHz. 1- A. Haziot et al., Phys. Rev. Lett. 110, 035301 (2013), Phys. Rev. B 87, 060509(R) (2013), and Phys. Rev. B 88, 014106 (2013). 2- A. D. Fefferman et al., submitted to Phys. Rev. B, Nov. 2013. ERC Grant AdG247258 SUPERSOLID and NSERC Canada.

  18. 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.

  19. Joint Problems

    MedlinePlus

    ... ankles and toes. Other types of arthritis include gout or pseudogout. Sometimes, there is a mechanical problem ... for more information on osteoarthritis, rheumatoid arthritis and gout. How Common are Joint Problems? Osteoarthritis, which affects ...

  20. Joint pain

    MedlinePlus

    ... or conditions. It may be linked to arthritis , bursitis , and muscle pain . No matter what causes it, ... Autoimmune diseases such as rheumatoid arthritis and lupus Bursitis Chondromalacia patellae Crystals in the joint: gout (especially ...

  1. 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.

  2. Electron paramagnetic resonance at dislocations in germanium

    SciTech Connect

    Pakulis, E.J.

    1982-06-01

    The first observation of the paramagnetic resonance of electrons at dislocations in germanium single crystals is reported. Under subband gap optical excitation, two sets of lines are detected: four lines about the <111> axes with g/sub perpendicular to/ = 0.34 and g/sub parallel/ = 1.94, and 24 lines with g/sub perpendicular to/ = 0.73 and g/sub parallel/ = 1.89 about <111> axes with the six-fold 1.2/sup 0/ distortion. This represents the first measurement of the disortion angle of a dislocation dangling bond. The possibility that the distortion results from a Peierls transition along the dislocation line is discussed.

  3. 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%.

  4. Brachial Artery Injury Accompanying Closed Elbow Dislocations

    PubMed Central

    Harnarayan, Patrick; Cawich, Shamir O.; Harnanan, Dave; Budhooram, Steve

    2014-01-01

    Introduction Brachial artery injuries from elbow dislocations are uncommon, but they may lead to disastrous consequences if the diagnosis is delayed. Presentation of case We report a case of a patient who sustained a fall onto the elbow, with dislocation and brachial artery injury, despite an ipsilateral radial pulse being palpable. Discussion Clinicians should maintain a high index of suspicion for brachial injury when patients present with a fall onto the elbow coupled with signs suggestive of fracture-dislocation, nerve injury and/or signs of limb ischemia. Frank ischamia, however, is uncommon as there is a rich collateral anastomosis in the upper limb. Conclusion A high index of suspicion should be maintained in order to make the diagnosis early. Exploration with excision of the injured segment and reverse vein interposition grafting is the treatment of choice in these cases. PMID:25644552

  5. [Long-term results of the treatment of Lisfranc fracture dislocation].

    PubMed

    García-Renedo, R J; Carranza-Bencano, A; Busta-Vallina, B; Ortiz-Segura, J; Plaza-García, S; Gómez-del Alamo, G

    2012-01-01

    We conducted an ambispective cohort study of 83 patients with a diagnosis of Lisfranc fracture dislocation from 1993 to 2008. The lesions were classified into two groups: pure dislocations and fracture dislocations of the Lisfranc joint using the Hardcastle-Reschamer classification. The results included the following data: sociodemographic and epidemiologic variables, lesion-related variables, clinical parameters, and the following clinical and functional assessment scales: Baltimore Painful Foot Score, Creighton-Nebraska Health Foundation, American Orthopaedic Foot and Ankle Society (AOFAS), and Hannover Scoring System. Sixty-three patients were treated surgically. Closed reduction and minimally invasive fixation with Kirschner nails were performed in 53 patients (63.9%), and open reduction with a dorsal approach and fixation with Kirschner nails in 10 cases (15.2%). In 46 cases de medial column was fixed, in 61 cases the intermediate column, and in 42 the lateral column. Sixty-six (79.5%) of the patients had complications including both acute and late ones. Regardless of the technique used, the purpose of treatment was the anatomical reduction of the involved joints. Based on our experience, we think that the use of Kirschner nails is effective, as it provides enough stiffness and stability. In general terms, this injury is not as disabling as it had been considered in the literature. Patients consider their discomfort as tolerable and compatible with the demands of their activities of daily living and they may perform their work considering the time limitations. PMID:23320326

  6. Arthroscopic Reduction and Stabilization of Chronic Perilunate Wrist Dislocations.

    PubMed

    Bhatia, Deepak N

    2016-04-01

    An acute perilunate wrist injury that is unreduced for more than 6 weeks results in severe disability, and even open reduction with stabilization through wide dorsal and volar approaches is technically challenging. This report describes an arthroscopic technique for reduction and percutaneous wire stabilization of a chronic perilunate wrist dislocations. The technique involves initial radiocarpal and midcarpal access through the 6R and 3-4 portals, and these portals are used for synovectomy and debridement of capsular flap tears. The midcarpal joint is accessed initially through the radiocarpal joint, and additional midcarpal portals are used for sequential perilunate adhesiolysis before carpal mobilization and reduction. A percutaneous wire drilled into the lunate is used as a joystick to manipulate the lunate into its anatomic alignment along the carpal bones, and percutaneous transcarpal wire fixation is performed to stabilize the carpus. Arthroscopic and fluoroscopic guidance is used to optimize anatomic reduction and to confirm stability. The wrist is immobilized for 6 weeks; the percutaneous wires are removed thereafter, and the wrist is mobilized. Overall, the arthroscopic technique provides a safe and reproducible method for treatment of this complex chronic injury. PMID:27354948

  7. A preliminary investigation of dislocation cell structure formation in metals using continuum dislocation dynamics

    NASA Astrophysics Data System (ADS)

    Xia, S. X.; El-Azab, A.

    2015-08-01

    A continuum dislocation dynamics model capable of capturing the cellular arrangements of dislocations in deformed crystals is presented. A small strain formulation of the model is given, followed by sample results of stress-strain behaviour, dislocation density evolution, dislocation cell pattern, lattice rotation, and geometrically necessary dislocation density and strain energy density distributions. An important finding of the current work is that dislocations form patterns under all circumstances due to their long range interactions. It is found, however, that the famous cell structure pattern forms when cross slip is activated. It is also found that cells are 3D sub-regions surrounded by dislocations walls in all directions, and they form, disappear, and reappear as a result of the motion of cell walls and formation of new walls by cross slip. It is further found that the average cell size is connected with the applied resolved shear stress according to the similitude principle observed in related experiments. The importance of these results is briefly discussed in the context of recrystallization.

  8. Dislocation dynamics in SiGe alloys

    NASA Astrophysics Data System (ADS)

    Yonenaga, I.

    2013-11-01

    The dislocation velocities and mechanical strength of bulk crystals of SixGe1-x alloys grown by the Czochralski method have been investigated by the etch pit technique and compressive deformation tests, respectively. Velocity of dislocations in the SiGe alloys of the composition range 0.004 < x < 0.08 decreases monotonically with an increase in Si content at temperature 450-700°C and under stress 3-24MPa. In contrast, velocity of dislocations in the composition range 0.92 < x < 1 first increases, then decreases and again increases with a decrease in Si content at temperature 750-850°C and under stress 3-30MPa. The velocity of dislocations was quantitatively evaluated as functions of stress and temperature. Stress-strain behaviour in the yield region of the SiGe alloys of composition 0 < x < 0.4 is similar to that of Ge at temperatures lower than about 600°C. However, the yield stress becomes temperature-insensitive at high temperatures and increases with increasing Si content. The stress-strain curves of the SiGe alloys of composition 0.95 < x < 1 are similar to those of pure Si at temperatures 800-1000°C and the yield stress increases with decreasing Si content down to x = 0.95. The yield stress of the SiGe alloys is dependent on the composition, being proportional to x(1-x), showing a maximum around x ≈ 0.5. Built-in stress fields related to local fluctuation of the alloy composition and the dynamic development of a solute atmosphere around the dislocations, may suppress the activities of dislocations and lead to the hardening of SiGe alloys.

  9. 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.

  10. 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.

  11. 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.

  12. Suppressing dislocations in normalized hypercubic smearing

    NASA Astrophysics Data System (ADS)

    DeGrand, Thomas; Shamir, Yigal; Svetitsky, Benjamin

    2014-09-01

    Normalized hypercubic smearing improves the behavior of dynamical Wilson-clover fermions, but has the unwanted side effect that it can occasionally produce spikes in the fermion force. These spikes originate in the chain rule connecting the derivative with respect to the smeared links to the derivative with respect to the dynamical links, and are associated with the presence of dislocations in the dynamical gauge field. We propose and study an action designed to suppress these dislocations. We present evidence for improved performance of the hybrid Monte Carlo algorithm. A side benefit is improvement in the properties of valence chiral fermions.

  13. Formation and structure of misfit dislocations

    NASA Astrophysics Data System (ADS)

    Nandedkar, A. S.; Srinivasan, G. R.; Murthy, C. S.

    1991-03-01

    We report here theoretical observations of the evolution of core structure of well-defined misfit dislocations arising from the spontaneous decomposition of highly strained coherent interfaces in a fcc bicrystal. We use a finely stepped energy-minimization technique and Lennard-Jones pair potential, which allowed Burgers-circuit construction and core-structure analysis. Simulations were made for (111) and (001) interfaces, which produced 60° and edge dislocations, respectively. The atomic configurations produced were consistent with those expected from the elasticity theory.

  14. 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. PMID:27477475

  15. [Clinical and ultrasonic diagnosis of congenital hip dislocation (dynamics of changes in early therapy)].

    PubMed

    Poul, J; Procházka, J; Klimsová, J; Janovec, M; Bajerová, J; Jíra, I; Straka, M; Sommernitz, M

    1990-08-01

    The authors present part of their prospective epidemiological study of congenital dysplasia of hip joints within which newborns were examined by ultrasonogram prior to the beginning of the therapy. Apart from the standard examination in the frontal plane after Graf they examined on principle also the ultrasonographic stability by the dynamic test after Schuler as well as by the application of the probe anteriorly with the simultaneous provocation according to Palmén. The authors have processed pathological ultrasonographic findings in 53 newborns (64 hip joints). The technique of the examination by ultrasound from the anterior approach is explained in detail. The comparison of both dynamic tests has shown that the examination from the anterior approach is considerably more sensitive than Schuler's dynamic test and also fully correlates with the clinical finding. It is a fact that the shift of the head in the flexion dorsally represents the most important component of the movement in unstable hip joint during provocation, it is far more noticeable than the lateralization of the head or the shift in the cranial direction. After achieving ultrasonographic stability the classical Graf method is sufficient for the registration of residual changes on the acetabular rim. The follow-up of patients until their complete healing has shown a surprisingly rapid remodellation of hip joints. The whole complex of clinically unstable hip joints has been divided into subgroups according to Graf classification. In type IIc or IId on the basis of ultrasonographic examination from the anterior approach the stable joints from the ultrasonographic viewpoint have been distinguished from unstable ones. The follow-up carried out in short intervals has shown that of longest duration is the remodellation of total dislocation and, on the contrary, of shortest duration is the healing of joints in the IIc or IId type. An absolute majority of affected hip joints have become normal until 3rd

  16. 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.

  17. 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 ...

  18. A model for nucleation of tin whisker through dislocation behavior

    NASA Astrophysics Data System (ADS)

    Nakai, K.; Sakamoto, T.; Kobayashi, S.; Takamizawa, M.; Murakami, K.; Hino, M.

    2009-05-01

    A model for the nucleation and growth processes of Sn whisker is offered. High density of localized screw dislocations by deformation form the dense spiral steps of atomic scale on Sn surface. The spiral steps would induce the nucleation of Sn whisker. Edge dislocations localized at the same region where dense screw dislocations exist supply Sn atoms to the Sn whisker through pipe diffusion. Both screw and edge dislocations would bend along almost one direction, namely, to relax the external shear stress. The image force also helps to bend the dislocations perpendicular to the whisker side-surface. The bending of dislocations at root of whisker leads the bend of whisker. The pipe diffusion of Sn atoms through edge dislocations from bulk Sn toward whisker is suppressed at the bent part of edge dislocation, resulting in release of Sn atoms inside whisker and leading to the growth of whisker near its root.

  19. Continuum dislocation dynamics: Towards a physical theory of crystal plasticity

    NASA Astrophysics Data System (ADS)

    Hochrainer, Thomas; Sandfeld, Stefan; Zaiser, Michael; Gumbsch, Peter

    2014-02-01

    The plastic deformation of metals is the result of the motion and interaction of dislocations, line defects of the crystalline structure. Continuum models of plasticity, however, remain largely phenomenological to date, usually do not consider dislocation motion, and fail when materials behavior becomes size dependent. In this work we present a novel plasticity theory based on systematic physical averages of the kinematics and dynamics of dislocation systems. We demonstrate that this theory can predict microstructure evolution and size effects in accordance with experiments and discrete dislocation simulations. The theory is based on only four internal variables per slip system and features physical boundary conditions, dislocation pile ups, dislocation curvature, dislocation multiplication and dislocation loss. The presented theory therefore marks a major step towards a physically based theory of crystal plasticity.

  20. Scale-free phase field theory of dislocations.

    PubMed

    Groma, István; Vandrus, Zoltán; Ispánovity, Péter Dusán

    2015-01-01

    According to recent experimental and numerical investigations, if a characteristic length (such as grain size) of a specimen is in the submicron size regime, several new interesting phenomena emerge during the deformation. Since in such systems boundaries play a crucial role, to model the plastic response it is crucial to determine the dislocation distribution near the boundaries. In this Letter, a phase-field-type continuum theory of the time evolution of an ensemble of parallel edge dislocations with identical Burgers vectors, corresponding to the dislocation geometry near internal boundaries, is presented. Since the dislocation-dislocation interaction is scale free (1/r), apart from the average dislocation spacing the theory cannot contain any length scale parameter. As shown, the continuum theory suggested is able to recover the dislocation distribution near boundaries obtained by discrete dislocation dynamics simulations. PMID:25615479

  1. Scale-Free Phase Field Theory of Dislocations

    NASA Astrophysics Data System (ADS)

    Groma, István; Vandrus, Zoltán; Ispánovity, Péter Dusán

    2015-01-01

    According to recent experimental and numerical investigations, if a characteristic length (such as grain size) of a specimen is in the submicron size regime, several new interesting phenomena emerge during the deformation. Since in such systems boundaries play a crucial role, to model the plastic response it is crucial to determine the dislocation distribution near the boundaries. In this Letter, a phase-field-type continuum theory of the time evolution of an ensemble of parallel edge dislocations with identical Burgers vectors, corresponding to the dislocation geometry near internal boundaries, is presented. Since the dislocation-dislocation interaction is scale free (1 /r ), apart from the average dislocation spacing the theory cannot contain any length scale parameter. As shown, the continuum theory suggested is able to recover the dislocation distribution near boundaries obtained by discrete dislocation dynamics simulations.

  2. Molecular dynamics simulations of dislocation instability in a stress gradient

    NASA Astrophysics Data System (ADS)

    Li, Ming; Selinger, Robin L.

    2003-04-01

    We present simulation studies of a morphological instability arising in dislocation dynamics. When an initially straight dislocation line is driven by a stress whose magnitude grows along the direction of dislocation motion, vibrational modes of the dislocation line with wavelength above a threshold value become linearly unstable. Molecular dynamics simulation studies of screw dislocations in Al demonstrate the onset of the instability during dislocation pair annihilation and annihilation at a crack tip. The wavelength of the unstable vibrational mode observed in each case agrees with the predictions of theoretical analysis. We discuss the role of temperature in nucleating the instability and speculate about how instabilities in dislocation motion could affect the density of threading dislocations during growth of heteroepitaxial thin films.

  3. Determination of the inhomogeneous dislocation density in a crystallographic texture

    SciTech Connect

    Satdarova, F. F.; Kozlov, D. A.

    2007-03-15

    Diffraction analysis of the mixed dislocation structure of a polycrystal with an orthorhombic texture is reported. A significant difference in the dislocation densities in the texture components of cold-deformed low-carbon steel has been revealed.

  4. Dislocation dynamics in Rayleigh-Bénard convection.

    PubMed

    Walter, Th; Pesch, W; Bodenschatz, E

    2004-09-01

    Theoretical results on the dynamics of dislocations in Rayleigh-Bénard convection are reported both for a Swift-Hohenberg model and the Oberbeck-Boussinesq equations. For intermediate Prandtl numbers the motion of dislocations is found to be driven by the superposition of two independent contributions: (i) the Peach-Koehler force and (ii) an advection force on the dislocation core by its self-generated mean flow. Their competition allows to explain the experimentally observed bound dislocation pairs. PMID:15447003

  5. 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.

  6. ACS Symposium Support

    SciTech Connect

    Kenneth D. Jordan

    2010-02-20

    The funds from this DOE grant were used to help cover the travel costs of five students and postdoctoral fellows who attended a symposium on 'Hydration: From Clusters to Aqueous Solutions' held at the Fall 2007 American Chemical Society Meeting in Boston, MA, August 19-23. The Symposium was sponsored by the Physical Chemistry Division, ACS. The technical program for the meeting is available at http://phys-acs.org/fall2007.html.

  7. Cervical facet dislocation adjacent to the fused motion segment

    PubMed Central

    Yokoyama, Kunio; Kawanishi, Masahiro; Yamada, Makoto; Tanaka, Hidekazu; Ito, Yutaka; Kuroiwa, Toshihiko

    2016-01-01

    This study reports on a case that forces re-examination of merits and demerits of anterior cervical fusion. A 79-year-old male was brought to the emergency room (ER) of our hospital after he fell and struck the occipital region of his head following excessive alcohol consumption. Four years prior, he had undergone anterior cervical discectomy and fusion of C5/6 and a magnetic resonance imaging (MRI) performed 3 years after this surgery indicated that he was suffering from degeneration of C6/7 intervertebral discs. After arriving at the ER, he presented motor impairment at level C7 and lower of manual muscle testing grade 1 as well as moderate loss of physical sensation from the trunk and peripheries of both upper limbs to the peripheries of both lower limbs (Frankel B). Cervical computed tomography (CT) indicated anterior dislocation of C6/7, and MRI indicated severe spinal cord edema. We performed manipulative reduction of C6/7 with the patient under general anesthesia. Next, we performed laminectomy on C5-T1 and posterior fusion on C6/7. Postoperative CT indicated that cervical alignment had improved, and MRI indicated that the spinal cord edema observed prior to surgery had been mitigated. Three months after surgery, motor function and sensory impairment of the lower limbs had improved, and the patient was ambulatory upon discharge from the hospital (Frankel D). In the present case, although C5 and 6 were rigidly fused, degeneration of the C6/7 intervertebral disc occurred and stability was compromised. As a result, even slight trauma placed a severe dynamic burden on the facet joint of C6/7, which led to dislocation. PMID:26933361

  8. Cervical facet dislocation adjacent to the fused motion segment.

    PubMed

    Yokoyama, Kunio; Kawanishi, Masahiro; Yamada, Makoto; Tanaka, Hidekazu; Ito, Yutaka; Kuroiwa, Toshihiko

    2016-01-01

    This study reports on a case that forces re-examination of merits and demerits of anterior cervical fusion. A 79-year-old male was brought to the emergency room (ER) of our hospital after he fell and struck the occipital region of his head following excessive alcohol consumption. Four years prior, he had undergone anterior cervical discectomy and fusion of C5/6 and a magnetic resonance imaging (MRI) performed 3 years after this surgery indicated that he was suffering from degeneration of C6/7 intervertebral discs. After arriving at the ER, he presented motor impairment at level C7 and lower of manual muscle testing grade 1 as well as moderate loss of physical sensation from the trunk and peripheries of both upper limbs to the peripheries of both lower limbs (Frankel B). Cervical computed tomography (CT) indicated anterior dislocation of C6/7, and MRI indicated severe spinal cord edema. We performed manipulative reduction of C6/7 with the patient under general anesthesia. Next, we performed laminectomy on C5-T1 and posterior fusion on C6/7. Postoperative CT indicated that cervical alignment had improved, and MRI indicated that the spinal cord edema observed prior to surgery had been mitigated. Three months after surgery, motor function and sensory impairment of the lower limbs had improved, and the patient was ambulatory upon discharge from the hospital (Frankel D). In the present case, although C5 and 6 were rigidly fused, degeneration of the C6/7 intervertebral disc occurred and stability was compromised. As a result, even slight trauma placed a severe dynamic burden on the facet joint of C6/7, which led to dislocation. PMID:26933361

  9. Postinfective skin contracture: a rare cause of fifth metatarsophalangeal joint subluxation

    PubMed Central

    Prakash, Jatin; Mehtani, Anil

    2014-01-01

    Dislocation or subluxation of the metatarsophalangeal joint (MTP) is common and usually follows a traumatic event. Non-traumatic causes usually include inflammatory arthritis (rheumatoid arthritis), connective tissue disorders, crowded shoewear or flexor digitorum longus tendon contracture. We present a very unusual case of subluxation of the fifth MTP joint following a postboil skin contracture. The case was treated with the release of contracture by Z-plasty. It resulted in concentric reduction of the joint and normal skin healing. PMID:25199201

  10. Postinfective skin contracture: a rare cause of fifth metatarsophalangeal joint subluxation.

    PubMed

    Prakash, Jatin; Mehtani, Anil

    2014-01-01

    Dislocation or subluxation of the metatarsophalangeal joint (MTP) is common and usually follows a traumatic event. Non-traumatic causes usually include inflammatory arthritis (rheumatoid arthritis), connective tissue disorders, crowded shoewear or flexor digitorum longus tendon contracture. We present a very unusual case of subluxation of the fifth MTP joint following a postboil skin contracture. The case was treated with the release of contracture by Z-plasty. It resulted in concentric reduction of the joint and normal skin healing. PMID:25199201

  11. 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…

  12. On onsagers principle, dislocation motion and hydrogen embrittlement

    NASA Technical Reports Server (NTRS)

    Louthan, M. R., Jr.; Mcnitt, R. P.

    1976-01-01

    Onsager's reciprocal relationships from the linear theory of irreversible thermodynamics are applied to hydrogen - dislocation interactions. Existing experimental evidence shows that dislocation motion causes localized hydrogen accumulation; thus, from the Onsager principle, localized hydrogen accumulations will affect dislocation motion and therefore the properties of metals and alloys exposed to hydrogen environments.

  13. 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…

  14. 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.

  15. 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.

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

    PubMed Central

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

    2008-01-01

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

  17. 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…

  18. Computer simulation of screw dislocation in aluminum

    NASA Technical Reports Server (NTRS)

    Esterling, D. M.

    1976-01-01

    The atomic structure in a 110 screw dislocation core for aluminum is obtained by computer simulation. The lattice statics technique is employed since it entails no artificially imposed elastic boundary around the defect. The interatomic potential has no adjustable parameters and was derived from pseudopotential theory. The resulting atomic displacements were allowed to relax in all three dimensions.

  19. 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) ...

  20. [Open total dislocation of the talus].

    PubMed

    Grabski, R S; Sosiński, R

    1992-01-01

    A case of 35 years old patient with open, total, fixed dislocation of the talus reduced with heel traction is presented. The Sudeck syndrome subsided after one year. Weight bearing was not allowed for 7 months. An examination after 2.5 years revealed minor osteoarthritis, full range of movement in the foot but limited walking capability. PMID:7555299

  1. An unusual variant of perilunate fracture dislocations

    PubMed Central

    Morin, Matthew L.; Becker, Giles W.

    2016-01-01

    Abstract Trans-scaphoid, trans-radial styloid, trans-triquetral perilunate fracture dislocations are rare. We describe a 19-year-old male who suffered this injury after crashing his bicycle. He underwent open reduction internal fixation and percutaneous pinning. Scaphoid union was achieved at 8 weeks. Near complete range of painless motion was achieved by 4 months.

  2. An unusual variant of perilunate fracture dislocations.

    PubMed

    Morin, Matthew L; Becker, Giles W

    2016-01-01

    Trans-scaphoid, trans-radial styloid, trans-triquetral perilunate fracture dislocations are rare. We describe a 19-year-old male who suffered this injury after crashing his bicycle. He underwent open reduction internal fixation and percutaneous pinning. Scaphoid union was achieved at 8 weeks. Near complete range of painless motion was achieved by 4 months. PMID:27583261

  3. Sociocultural Dislocation: Beyond the Dual Perspective.

    ERIC Educational Resources Information Center

    De Hoyos, Genevieve; And Others

    1986-01-01

    Moves beyond the dual perspective model and beyond medical and ecological systems models to suggest a sociocultural approach and presents a three-stage model for practice with minority clients. Suggests that practice with minorities focus on the degree and kind of dislocation--social, cultural, or sociocultural--suffered by individual clients.…

  4. Copper passivation of dislocations in silicon

    SciTech Connect

    Lee, J.; Morrison, S.R.

    1988-12-15

    The J-V characteristics of metal-insulator-semiconductor solar cells fabricated on Si samples which are damaged (lapped) with 1-..mu..m grit size of Al/sub 2/O/sub 3/ are substantially degraded. The introduction of copper at 250--400 /sup 0/C passivates the dislocations. The copper is diffused in from the surface. Anodic oxidation followed by etching in aqua regia and 48% HF was used to remove excess copper remaining on the damaged surface and to etch away controlled amounts of the silicon wafers. The experimental results are compared to the model of Divigalpitiya and Morrison (J. Appl. Phys. 60, 406 (1986)). It is concluded using the model that copper passivation reduces the product of the density of hole traps and the capture cross section of hole traps and may also increase the specific conductance of the dislocations. Results for samples lapped with finer-grit alumina (0.3 ..mu..m) seem qualitatively different from those with 1-..mu..m alumina. The variation in dislocation density as a function of depth into the surface is used to explain the difference qualitatively. The dislocation density decreases rapidly with distance from the damaged surface.

  5. Imaging dislocation cores – the way forward

    SciTech Connect

    Spence, John; Kolar, H.R.; Hembree, G; Humphreys, C.J.; Barnard, J.; Datta, R.; Koch, C.; Ross, F.M.; Justo, J.F.

    2006-10-11

    Although the sub-angstrom resolution of the modern transmission electron microscope (TEM) has made major contributions to defect structure analysis in many fields (such as oxides, interfaces, nanoparticles and superconductors) it has yielded little direct information on the core structure of dislocations. We suggest that ‘‘forbidden reflection’’ lattice images recorded in an ultra-high vacuum TEM in projections normal to the dislocation line could provide interpretable images of cores at atomic resolution. These could answer crucial questions, such as the nature of kinks, core reconstruction and periodicity, the nature of obstacles, and help distinguish obstacle theories of kink motion from the secondary Peierls–valley Hirth–Lothe theory. We give experimental forbidden reflection images and a new image obtained from silicon under UHV conditions with atomically smooth surfaces, whose preparation did not anneal out all dislocations. We also show experimental coherent nanodiffraction patterns and scanning transmission electron microscope (STEM) images recorded with the beam parallel to the core, so that core reconstruction can be expected to introduce a ‘‘half-order’’ Laue zone ring. We discuss the contribution that energy-loss spectroscopy from dislocation cores can be expected to make if a nanoprobe beam is used.

  6. Effects of Dislocations on Minority Carrier Lifetime in Dislocated Float Zone Silicon

    SciTech Connect

    Karoui, A.; Zhang, R.; Rozgonyi, G. A.; Ciszek, T. F.

    2002-08-01

    We present a correlation of Microwave Photoconductance Decay minority carrier lifetime with dislocation density in high purity Float Zone silicon. Electron Beam Induced Current (EBIC) images were carefully aligned to lifetime maps and depth profiling of individual defect electrical activity was done by varying the bias of Schottky diodes. The data presented provides a relationship between lifetime variations and EBIC contrast, based on dislocation density and impurity decoration in the near surface zone.

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

    PubMed

    Kim, J H; Nam, D H

    2015-10-01

    Most surgeons agree that closed treatment provides the best results for condylar fractures in children. Nevertheless, treatment of the paediatric mandibular condyle fracture that is severely displaced or dislocated is controversial. The purpose of this study was to investigate the long-term clinical and radiological outcomes following the treatment of displaced or dislocated condylar fractures in children using threaded Kirschner wire and external rubber traction. This procedure can strengthen the advantage of closed reduction and make up for the shortcomings of open reduction. From March 1, 2005 to December 25, 2011, 11 children aged between 4 and 12 years with displaced or dislocated mandibular condyle fractures were treated using threaded Kirschner wire and external rubber traction under portable C-arm fluoroscopy. All patients had unilateral displaced or dislocated condylar fractures. The follow-up period ranged from 24 to 42 months (mean 29.3 months). Normal occlusion and pain-free function of the temporomandibular joint, without deviation or limitation of jaw opening, was achieved in all patients. This closed reduction technique in displaced or dislocated condylar fractures in children offers a reliable solution in preventing the unfavourable sequelae of closed treatment and the open technique, such as altered morphology, functional disturbances, and facial nerve damage. PMID:26117724

  8. 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

  9. Medial Patellofemoral Ligament Reconstruction for Patellar Dislocation

    PubMed Central

    Mackay, Nicola D.; Smith, Nicholas A.; Parsons, Nick; Spalding, Tim; Thompson, Peter; Sprowson, Andrew P.

    2014-01-01

    Background: With improved understanding of the biomechanical importance of the medial patellofemoral ligament (MPFL), its reconstruction for patellar dislocation has become increasingly popular. The aim of this systematic review was to critically determine the effectiveness of MPFL reconstruction for patellar dislocation. Hypothesis: MPFL reconstruction for patellar dislocation leads to a low redislocation rate with improved Kujala scores. Study Design: Systematic review; Level of evidence, 4. Methods: A literature search was performed using Embase and Medline (Ovid) databases. Inclusion criteria included first-time and recurrent patellar dislocation, subluxation, or persistent instability with a minimum follow-up of 12 months and documentation of postoperative redislocation rate or Kujala score. The studies were systematically appraised, and a meta-analysis was performed. Results: Twenty-two studies were included: 2 randomized controlled trials, 3 parallel case series, and 17 case series. There were a total of 655 knees in the review, with an age range at time of surgery from 11 to 52 years. The pooled postoperative redislocation rate from all 17 case series showed a mean of 2.44%. The pooled preoperative Kujala scores from 12 case series showed a mean of 51.6 (95% CI, 46.71-56.49). The pooled postoperative Kujala scores from 16 case series showed a mean of 87.77 (95% CI, 85.15-90.39). Conclusion: Although the studies were of low quality, the meta-analysis of 17 case series shows that MPFL reconstruction for recurrent patellar dislocation results in a significant improvement in Kujala scores, a low redislocation rate, and acceptable complication rate. Randomized trials would be needed to draw influences on the superiority of MPFL reconstruction compared with other treatments. PMID:26535352

  10. Proximal tibiofibular joint: Rendezvous with a forgotten articulation.

    PubMed

    Sarma, Amitav; Borgohain, Bhaskar; Saikia, Bishwajeet

    2015-01-01

    The proximal tibiofibular joint (PTFJ) is a plane type synovial joint. The primary function of the PTFJ is dissipation of torsional stresses applied at the ankle and the lateral tibial bending moments besides a very significant tensile, rather than compressive weight bearing. Though rare, early diagnosis and treatment of the PTFJ dislocation are essential to prevent chronic joint instability and extensive surgical intervention to restore normal PTFJ biomechanics, ankle and knee function, especially in athletes prone to such injuries. PTFJ dislocations often remain undiagnosed in polytrauma scenario with ipsilateral tibial fracture due to the absence of specific signs and symptoms of PTFJ injury. Standard orthopedic textbooks generally describe no specific tests or radiological signs for assessment of the integrity of this joint. The aim of this paper was to review the relevant clinical anatomy, biomechanics and traumatic pathology of PTFJ with its effect on the knee emphasizing the importance of early diagnosis through a high index of suspicion. Dislocation of the joint may have serious implications for the knee joint stability since fibular collateral ligament and posterolateral ligament complex is attached to the upper end of the fibula. Any high energy knee injury with peroneal nerve palsy should immediately raise the suspicion of PTFJ dislocation especially if the mechanism of injury involved knee twisting in flexion beyond 80° and in such cases a comparative radiograph of the contralateral side should be performed. Wider clinical awareness can avoid both embarrassingly extensive surgeries due to diagnostic delays or unnecessary overtreatment due to misinformation on the part of the treating surgeon. PMID:26538753

  11. Proximal tibiofibular joint: Rendezvous with a forgotten articulation

    PubMed Central

    Sarma, Amitav; Borgohain, Bhaskar; Saikia, Bishwajeet

    2015-01-01

    The proximal tibiofibular joint (PTFJ) is a plane type synovial joint. The primary function of the PTFJ is dissipation of torsional stresses applied at the ankle and the lateral tibial bending moments besides a very significant tensile, rather than compressive weight bearing. Though rare, early diagnosis and treatment of the PTFJ dislocation are essential to prevent chronic joint instability and extensive surgical intervention to restore normal PTFJ biomechanics, ankle and knee function, especially in athletes prone to such injuries. PTFJ dislocations often remain undiagnosed in polytrauma scenario with ipsilateral tibial fracture due to the absence of specific signs and symptoms of PTFJ injury. Standard orthopedic textbooks generally describe no specific tests or radiological signs for assessment of the integrity of this joint. The aim of this paper was to review the relevant clinical anatomy, biomechanics and traumatic pathology of PTFJ with its effect on the knee emphasizing the importance of early diagnosis through a high index of suspicion. Dislocation of the joint may have serious implications for the knee joint stability since fibular collateral ligament and posterolateral ligament complex is attached to the upper end of the fibula. Any high energy knee injury with peroneal nerve palsy should immediately raise the suspicion of PTFJ dislocation especially if the mechanism of injury involved knee twisting in flexion beyond 80° and in such cases a comparative radiograph of the contralateral side should be performed. Wider clinical awareness can avoid both embarrassingly extensive surgeries due to diagnostic delays or unnecessary overtreatment due to misinformation on the part of the treating surgeon. PMID:26538753

  12. Te homogeneous precipitation in Ge dislocation loop vicinity

    NASA Astrophysics Data System (ADS)

    Perrin Toinin, J.; Portavoce, A.; Texier, M.; Bertoglio, M.; Hoummada, K.

    2016-06-01

    High resolution microscopies were used to study the interactions of Te atoms with Ge dislocation loops, after a standard n-type doping process in Ge. Te atoms neither segregate nor precipitate on dislocation loops, but form Te-Ge clusters at the same depth as dislocation loops, in contradiction with usual dopant behavior and thermodynamic expectations. Atomistic kinetic Monte Carlo simulations show that Te atoms are repulsed from dislocation loops due to elastic interactions, promoting homogeneous Te-Ge nucleation between dislocation loops. This phenomenon is enhanced by coulombic interactions between activated Te2+ or Te1+ ions.

  13. 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.

  14. Pediatric Monteggia Fracture-Dislocations: Avoiding Problems and Managing Complications.

    PubMed

    Chin, Kenneth; Kozin, Scott H; Herman, Martin; Horn, Bernard D; Eberson, Craig P; Bae, Donald S; Abzug, Joshua

    2016-01-01

    Monteggia fracture-dislocations typically involve a dislocation of the radial head with an associated fracture of the ulnar shaft. The prompt diagnosis and treatment of these acute injuries result in excellent outcomes. Unfortunately, a Monteggia fracture-dislocation is often missed during diagnostic testing and results in a chronic Monteggia fracture-dislocation. The subsequent timing and treatment of chronic Monteggia fracture-dislocations are debatable because outcomes are suboptimal. Therefore, it is critical that the initial injury be correctly diagnosed and treated as close to the time of injury as possible to ensure excellent outcomes. PMID:27049208

  15. Joint lubrication.

    PubMed

    McCutchen, C W

    1983-01-01

    The fine-pored, easily compressed articular cartilage provides animal joints with self-pressurized hydrostatic (weeping) lubrication. The solid skeletons of the cartilages press against each other, but so lightly that their rubbing is lubricated successfully by synovial fluid--a boundary lubricant too weak to lubricate ordinary bearings. PMID:6317095

  16. Unstable elbow dislocations: the description and cadaveric feasibility study of a new surgical technique

    PubMed Central

    Harris, Mark; Bishop, Timothy; Bernard, Jason

    2015-01-01

    Introduction: A small proportion of simple elbow dislocations are grossly unstable and joint congruence is not maintained after reduction. In this rare situation operative treatment is indicated. We describe a new intra articular reconstruction that utilises a slip of triceps tendon to provide immediate stability to the elbow. Methods: We assessed 20 cadaveric elbows, measuring the length of triceps tendon available and required to complete the reconstruction. We then sequentially sectioned the ligamentous stabilisers of an elbow before performing the new technique. We measured the displacement and angulation possible at the elbow before and after the reconstruction. Results: All 20 elbows had sufficient triceps tendon length to complete the new technique. Prior to the reconstruction greater than 30 mm of joint distraction and 90 degrees varus or valgus angulation was possible. Following the reconstruction it was not possible to re-dislocate the elbow. Only 2 mm of joint distraction and 10 degrees of varus or valgus angulation were possible with the triceps graft fixed in position. Discussion: This novel technique elegantly avoids many of the problems associated with current methods. We have demonstrated that it is technically feasible and easy to perform with minimal equipment requirements or costs. PMID:27163079

  17. Multiscale characterization of deformation mechanisms in the weld joint of a nickel-based superalloy

    SciTech Connect

    Barabash, Oleg M; Horton Jr, Joe A; Babu, Sudarsanam S; Vitek, John Michael; David, Stan A; Ice, Gene E; Barabash, Rozaliya

    2005-01-01

    Multiscale plastic deformation in the heat affected zone (HAZ) of a Ni-based single crystal superalloy has been characterized using white microbeam synchrotron diffraction measurements together with OIM imaging, electron and optical microscopy. Characteristic length scales on the macro, meso and nano scale are determined. Dissolution of the gamma' - phase particles during heating and secondary precipitation of gamma' during cooling is found, as well as formation and multiplication of dislocations. This process is more intense as one approaches the fusion line (FL). In the regions immediately neighboring the FL, gamma' - phase particles dissolve completely and re-precipitate from the solid solution in the form of very small (10-20nm) particles. In the immediate vicinity of the FL, the temperature gradient and the rate of it's change reaches maximal values and causes the formation of large amounts of dislocations. Dislocations are concentrated in the gamma matrix of the single crystal superalloy. X-ray Laue diffraction (both conventional and microbeam) and electron microscopy show that alternating dislocations slip systems dominate in the HAZ with Burgers vector b=[110] and dislocation lines [1-12] and [1-1-2] ; or b=[-110], dislocation lines [112] and [11-2] . Each of these two dislocation groups forms two Z-shaped dislocation lines fluctuating around two cubic directions [100] and [010]. Local lattice rotations in different zones of the weld joint are linking with the microslip events in different zones of the weld.

  18. Dislocation dynamics in hexagonal close-packed crystals

    DOE PAGESBeta

    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 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. Dislocations With Edge Components in Nanocrystalline bcc Mo

    SciTech Connect

    G. M. Cheng; W. Z. Xu; W. W. Jian; H. Yuan; M. H. Tsai; Y. T. Zhu; Y. F. Zhang; Paul C. Millett

    2013-07-01

    We report high-resolution transmission electron microscopy (HRTEM) observation of a high density of dislocations with edge components (approximately 1016 m-2) in nanocrystalline (NC) body-centered cubic (bcc) Mo prepared by high-pressure torsion. We also observed for the first time of the 1/2 <111> and <001> pure edge dislocations in NC Mo. Crystallographic analysis and image simulations reveal that the best way using HRTEM to study dislocations with edge components in bcc systems is to take images along <110> zone axis, from which it is possible to identify 1/2 <111> pure edge dislocations, and edge components of 1/2 <111> and <001> mixed dislocations. The <001> pure edge dislocations can only be identified from <100> zone axis. The high density of dislocations with edge components is believed to play a major role in the reduction of strain rate sensitivity in NC bcc metals and alloys.

  20. X-ray diffraction from hexagonal dislocation networks

    NASA Astrophysics Data System (ADS)

    Kopp, Viktor S.; Kaganer, Vladimir M.

    2014-10-01

    We built the honeycomb networks of misfit dislocations by combining angular dislocations. Two different models of the disorder in the dislocation network are explored, the random shifts of nodes and random sources of distortion. The displacement fields of disturbed dislocation networks are used to simulate the X-ray diffraction patterns by Monte Carlo method. We find that substantial disorder is needed for random shifts to be experimentally observable as diffuse scattering. The model of random distortion sources produces comparable diffuse scattering with the dislocation network looking closer to the initial perfect structure. The diffraction patterns due to distorted honeycomb dislocation networks are compared with the ones due to triangular networks of straight dislocations. The disorder parameters of the latter networks can be chosen to produce diffraction patterns similar to the former.

  1. Observation of dislocations and twins in explosively compacted alumina

    SciTech Connect

    Yust, C.S.; Harris, L.A.

    1980-01-01

    The microstructure at the half-radius position of a polycrystalline alumina rod formed by explosive compaction has been studied by transmission electron microscopy. The as-compacted lattice is composed of differently misoriented bands aligned predominantly in one direction. Such bands may correspond to frequently observed shock lamellae. The band edges are defined by dislocation arrays lying on the basal planes of the hexagonal alumina lattice. The dislocations have Burgers vectors of the type (1120) and (1010), which are the Burgers vectors of slip dislocations in the basal plane. Basal plane twinning is also observed, and the twin boundaries are found to contain interfacial dislocations. While dislocation generation occurs primarily on basal planes, some dislocation activity is also noted on prism, (1100), and on rhombohedral, (1101), planes. Nonbasal twinning, however, has not been detected. The lattice damage is discussed in terms of possible dislocation and twinning mechanisms.

  2. Dislocation dynamics in hexagonal close-packed crystals

    NASA Astrophysics Data System (ADS)

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

    2016-09-01

    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 < c + a > and other dislocations with large Burgers vectors defined as composite dislocations are examined and a new topological operation is proposed to enable their dissociation. 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.

  3. The kink-pair nucleation in edge dislocation motion

    NASA Astrophysics Data System (ADS)

    Yu, Song; Wang, Chong-Yu; Yu, Tao

    2009-03-01

    The motion of edge dislocations (EDs) and kinked EDs in body-centered cubic Fe are studied at atom level. We find the kink-pair nucleation mechanism directly from the atom configuration evolution of dislocation, the EDs move primarily by the kink-pair nucleation, and the pre-existing kink does not affect this motion mode. The result is in agreement with the energy calculation. Furthermore, the Peierls stress, dislocation velocity, and phonon-drag coefficient are discussed. There are obviously two motion regions with different stresses. In the low-stress region, the stress exercises a great influence on the dislocation motion, the dislocation velocity increase significantly with the increase of stress. In the high-stress region, however, phonon drag practice a dominant factor on the dislocation motion, the dislocation move with approximately constant speed close to the transverse speed of sound.

  4. Use of a bivalve finger fracture orthosis for a new treatment protocol of a PIP comminuted fracture and dorsal dislocation.

    PubMed

    Monasterio, Marisol; Longsworth, Kathleen A; Viegas, Steven

    2015-01-01

    As therapists and physicians, we often need to work with our patients to cater treatment accordingly. These authors describe how they modified a treatment protocol for a patient that sustained a proximal interphalangeal joint comminuted fracture and dorsal dislocation, but refused surgery. Their modification allowed the patient to return to full activities. - Victoria Priganc, PhD, OTR, CHT, CLT, Practice Forum Editor. PMID:25301399

  5. Superclimb of Dislocations in Solid 4He

    NASA Astrophysics Data System (ADS)

    Kuklov, Anatoly

    2011-03-01

    Edge dislocation with superfluid core can perform superclimb -- non-conservative motion (climb) assisted by superflow along its core. Such dislocation, with Burgers vector along the C-axis, has been found in ab initio simulations of hcp solid 4. Uniform network of superclimbing dislocations can induce isochoric compressibility which is finite (in contrast to ideal solid where it vanishes) and, practically, independent of the network density. Here N is total number of atoms and is chemical potential. Such giant response has been observed by Ray and Hallock during superfluid flow events through solid He4. Study of superclimbing dislocation within the model of Granato-Lücke string, subjected to Peierls potential and to vanishing bias by , has found that exhibits wide peak in the intermediate range of temperatures (T) - above some determined by Peierls energy and below above which superfluidity of the core essentially vanishes. Non-Luttinger type behavior characterized by K scaling as some power χ of dislocation length is observed in the wide peak region. Biasing superclimbing dislocation by finite μ (due to a contact with liquid through vycor electrodes,) can induce core roughening caused by thermally assisted tunneling of jog-antijog pairs through the barrier produced by combination of Peierls potential and the bias. The threshold for this effect scales as with some power a~ 1.7. The roughening is found to be hysteretic below some temperature Thyst , with TR determining temperature of thermal roughening, He exhibits strong and narrow resonant peak leading to a dip in the core superfluid sound velocity. This mechanism is proposed as an explanation for a strong and narrow dip observed in critical superflow rate. It is found that the dip characteristics are sensitive to the bias by μ and, therefore, this can be used as a test for the proposed mechanism. It is also predicted that the dip depth at given μc ~ 1 /La should be periodic in χ with the period T . This

  6. 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.

  7. 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

  8. 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.

  9. 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.

  10. Characterization of dislocation wall spacing distributions

    SciTech Connect

    Godfrey, A.; Hughes, D.A.

    1997-12-31

    While conventionally the length scale of dislocation microstructures has been characterized by only a mean value it is also of interest to know the shape of the wall spacing distribution. In order to investigate the ability to characterize such spacing distributions for near-planar boundaries a model has been developed allowing the construction of a series of dislocation walls that can be sectioned in any plane allowing spacing distributions of the traces to be calculated. Results suggest that distribution shape is not adversely affected by either test section or by realistically low numbers of measurements. Consequently experimental measurements have been made on both low strain ({epsilon} = 0.2 and {epsilon} = 0.3) and high strain ({epsilon} = 2.7) samples. The distributions for all three strains exhibit similar shapes and can be scaled to a single curve for the probability density function.

  11. Treatment of complex elbow fracture-dislocations.

    PubMed

    Chan, Kevin; King, Graham J W; Faber, Kenneth J

    2016-06-01

    Successful management of complex elbow fracture-dislocations requires, in part, recognition of the overall injury pattern, which can aid in the identification of concomitant bony and soft tissue injuries. Trans-olecranon fracture-dislocations are best treated surgically with stable anatomic restoration of the trochlear notch. Terrible triad elbow injuries are believed to be caused by a valgus posterolateral force. Although select terrible triad injuries can be managed non-operatively, the majority of injuries are treated with stable surgical repair to allow early elbow motion. Unlike terrible triads, varus posteromedial forces are theorized to cause anteromedial coronoid fractures. These are usually associated with LCL disruptions, but do not have concomitant MCL or radial head injuries. A subset of anteromedial coronoid fractures can also be managed non-operatively. Internal fixation is recommended for injuries associated with large fracture fragments or elbow instability preventing early motion. PMID:26984334

  12. Nanovoid Cavitation by Dislocation Emission in Aluminum

    NASA Astrophysics Data System (ADS)

    Marian, Jaime; Knap, Jaroslaw; Ortiz, Michael

    2004-10-01

    This Letter is concerned with the determination of the transition paths attendant to nanovoid growth in aluminum under hydrostatic tension. The analysis is, therefore, based on energy minimization at 0K. Aluminum is modeled by the Ercolessi-Adams embedded-atom method, and spurious boundary artifacts are mitigated by the use of the quasicontinuum method. Our analysis reveals several stages of pressure buildup separated by yield points. The first yield point corresponds to the formation of highly stable tetrahedral dislocation junctions around the surfaces of the void. The second yield point is caused by the dissolution of the tetrahedral structures and the emission of conventional 1/2<110>{111} and anomalous 1/2<110>{001} dislocation loops.

  13. First principles determination of dislocation properties.

    SciTech Connect

    Hamilton, John C.

    2003-12-01

    This report details the work accomplished on first principles determination of dislocation properties. It contains an introduction and three chapters detailing three major accomplishments. First, we have used first principle calculations to determine the shear strength of an aluminum twin boundary. We find it to be remarkably small ({approx}17 mJ/m{sup 2}). This unexpected result is explained and will likely pertain for many other grain boundaries. Second, we have proven that the conventional explanation for finite grain boundary facets is wrong for a particular aluminum grain boundary. Instead of finite facets being stabilized by grain boundary stress, we find them to originate from kinetic effects. Finally we report on a new application of the Frenkel-Kontorova model to understand reconstructions of (100) type surfaces. In addition to the commonly accepted formation of rectangular dislocation arrays, we find numerous other possible solutions to the model including hexagonal reconstructions and a clock-rotated structure.

  14. 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.

  15. 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.

  16. Energetics and Noise in dislocation patterning.

    SciTech Connect

    Thomson, R. M.; Koslowski, M.; LeSar, R. ,

    2004-01-01

    The competition between energy and noise in the patterning transition in deformation is explored by employing a 2D model of parallel straight edge dislocations. We define a generalized force for ordering and show that at mechanical equilibrium, the ordering force is equal to the average back stress noise on the slip plane. We consider a system subjected to a total external strain that is a uniform linear function of time. When the external stress reaches a critical value that depends on the instantaneous state of strain and dislocation content, a discrete strain event occurs (what we have called elsewhere a percolation event) with the formation of one or perhaps a few micro slip steps on the surface. Within these micro slip bands, the dislocation content increases in a time short compared to the time between strain events. After the stress drop associated with the stain event, the strain stops. During the time between events, the configuration relaxes to a new equilibrium configuration, which may include thermally generated recovery. As the stress again builds owing to the continuously increasing total strain, it reaches a new critical stress determined by the newly achieved dislocation configuration. Our modeling addresses the changes during the relaxation of the system in the time between events. In our model, the initial state is a random configuration i.e., it does not contain any memory of the previous state of the deforming system. This is an extreme assumption, because in a real system, the order will evolve from one event to the next. Nevertheless, if the real system does order, we expect this to be captured in the model - we will simply be careful not to predict the quantitative order in the evolving system from our modeling.

  17. Types of Traumatic Lens Dislocations at Larkana.

    PubMed

    Shah, Syed Imtiaz Ali; Shah, Shujaat Ali; Rai, Partab; Siddiqui, Shahid Jamal; Abbasi, Safdar Ali; Katpar, Naeem Akhtar

    2016-08-01

    The objective of this study was to determine the pattern of traumatic lens dislocations presenting at our institute. This may help develop the preventive strategies. The number of cases of traumatic lens dislocations, presented at the Department of Ophthalmology, Chandka Medical College, Larkana, Pakistan, from January 2002 to June 2015, were 59 including 61.02% (n=36) males and 38.98% (n=23) females. Cause of trauma was wood or plant impalement in 35.6% (n=21) cases, cracker blast in 13.55% (n=8) cases, fall on ground in 11.86% (n=7) cases, penetrating injuries with needle, scissors or knife in 10.16% (n=6) cases, road traffic accidents in 10.16% (n=6) cases, sports injuries (cricket ball and gulle danda) in 8.47% (n=5) cases, firearm injuries in 5.1% (n=3) cases, and fist hitting in 5.1% (n=3) cases. Lens was dislocated posteriorly in 33.90% (n=20) cases, anteriorly in 25.42% (n=15) cases, inferiorly in 11.86% (n=7) cases, medially in 10.17% (n=6) cases, laterally in 10.17% (n=6) cases, superiorly in 6.78% (n=4) cases, and a single (1.69%) case of lenticele was seen. PMID:27539772

  18. 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.

  19. 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.

  20. 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

  1. 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. PMID:25013857

  2. 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

  3. Probing the character of ultra-fast dislocations

    DOE PAGESBeta

    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 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

  4. Probing the character of ultra-fast dislocations.

    PubMed

    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

  5. 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

  6. 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.

  7. 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.

  8. AC solar cell

    SciTech Connect

    Schutten, H.P.; Benjamin, J.A.; Lade, R.W.

    1986-03-18

    An AC solar cell is described comprising: a pair of PN junction type solar cells connected in antiparallel between a pair of main terminals; and means for electrically directing light alternatingly without mechanical movement on the PN junctions to generate an alternating potential across the main terminals.

  9. AC 67 Launch Video

    NASA Technical Reports Server (NTRS)

    1987-01-01

    Live footage of the Unmanned Atlas Centaur (AC) 67 launch is presented on March 26, 1987 at the WESH television station in Florida. Lightning is shown after 49 seconds into the flight. The vehicle is totally destroyed due to a cloud-to-ground lightning flash.

  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. A Case of Bilateral Anterior Gleno-Humeral Dislocation following First Time Seizure

    PubMed Central

    Wheelton, Andrew; Dowen, Daniel

    2015-01-01

    Introduction: Bilateral anterior shoulder dislocation following a seizure has recently been demonstrated as being more common than previously believed with 44 cases in the literature. This case is unique as it was caused by a first time seizure and there was no associated fracture of the humerus. Case Report: A previously fit and well 32 year old man presented to the Emergency Department following a convulsive episode. On initial assessment he was drowsy and the focus of investigation was the cause of the seizure, he was prepared for transfer to the medical ward. As he became more alert he complained of bilateral shoulder pain. Further clinical exam highlighted he had reduced range of movement in the shoulder joint bilaterally with a symmetrical clinical appearance of gleno-humeral dislocation. Radiographs confirmed bilateral anterior gleno-humeral dislocations which were reduced under sedation uneventfully. Conclusion: Post ictal patients can be difficult to assess when drowsy. Although not all seizures require musculoskeletal examination attending medical staff should remain vigilant to the possibility of injury following seizure to afford prompt diagnosis and treatment. PMID:27299040

  12. 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. PMID:26875088

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

    PubMed

    Dolera, Mario; Malfassi, Luca; Bianchi, Cristina; Carrara, Nancy; Corbetta, Laura; Finesso, Sara; Marcarini, Silvia; Mazza, Giovanni; Pavesi, Simone; Sala, Massimo

    2016-07-01

    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

  14. Patella Dislocation with Vertical Axis Rotation: The “Dorsal Fin” Patella

    PubMed Central

    Gamble, David; Carrothers, Andrew D.; Khanduja, Vikas

    2015-01-01

    A 44-year-old woman presented following minor trauma to her right knee. While dancing she externally rotated around a planted foot and felt sudden pain in her right knee. She presented with her knee locked in extension with a “dorsal fin” appearance of the soft tissues tented over the patella. This was diagnosed as a rare case of an intraarticular patella dislocation, which was rotated 90 degrees about the vertical axis. Closed reduction in the emergency room was unsuccessful but was achieved in theatre under general anaesthetic with muscle relaxation. Postreduction arthroscopy demonstrated that no osteochondral or soft tissue damage to the knee had been sustained. In patients presenting with a knee locked in extension with tenting of skin over the patella (the “dorsal fin” appearance), intra-articular patella dislocation should be suspected. Attempts to reduce vertical patella dislocations under sedation with excessive force or repeatedly without success should be avoided to prevent unnecessary damage to the patellofemoral joint. In this clinical situation we recommend closed reduction under general anaesthetic followed by immediate knee arthroscopy under the same anaesthetic to ensure that there is no chondral damage to the patella or femoral trochlea and to rule out an osteochondral fracture. PMID:25883819

  15. Articular capsule repair in initial artificial hip replacement via anterolateral approach to the hip joint.

    PubMed

    Zhang, B L; Wang, F; Tian, M B; Yin, W L; You, X Y; Li, D; Ma, L G; Xing, L Q

    2016-01-01

    This study was carried out to explore articular capsule repair in first artificial hip replacement (AHR) via anterolateral approach and its influence on postoperative dislocation. A total of 292 patients who received AHR via anterolateral approach and had the articular capsule repaired in People’s Hospital of Zhengzhou (Henan, China) from February 2008 to February 2014 were selected and divided into total hip replacement (THR) group (group A1) and artificial femoral head replacement (AFHR) group (group A2). Five hundred and five cases in the control group treated using the same approach but receiving no articular capsule repair were divided into THR group (group B1) and AFHR group (group B2). Condition of postoperative dislocation was compared between the two groups. All cases were followed up for 6 months to 5 years (average: 3.75 years); it was noted that the difference in average age, gender, disease constitution and follow-up time in the two groups was not significant (P>0.05). Moreover, groups A1 and B1 were found with 1 case of early hip joint dislocation (0.73%) and 13 cases of hip joint dislocation (5.24%) respectively post-operatively, and the comparison between the two groups was statistically significant (P less than 0.05). One case of hip joint dislocation (0.65%) was found in group A2 and 5 cases (1.95%) in group B2 in early post operation and the difference between two groups had no statistical significance (P>0.05). Neither the repair group nor the control group developed late-onset dislocation after the operation. Thus, we can state that articular capsule repair is feasible during the first AHR via anterolateral approach, which decreases the occurrence of early hip joint dislocation after operation and proves that repairing articular capsule during AFHR via anterolateral approach is unnecessary. PMID:27358130

  16. Lisfranc fracture-dislocation in a female soccer athlete.

    PubMed

    Haddix, Beth; Ellis, Karen; Saylor-Pavkovich, Estee

    2012-04-01

    Individuals with midfoot injuries may present to physical therapists in a variety of clinical settings. The ability of the physical therapy practitioner to optimally manage the care of such an individual may be dependent on understanding the diagnostic imaging that is indicated or has been been completed. Among the potentially most debilitating midfoot injuries are Lisfranc fracture-dislocations. This case outlines the use of conventional radiology, standard computerized tomography (CT), and three-dimensional CT for differential diagnosis of Lisfranc and associated midfoot injury in a 26 year-old female recreational athlete. Her subsequent surgical and post-surgical management is briefly discussed.Physical therapists evaluating patients with suspected midfoot injuries should be cognizant of the tendency for Lisfranc injuries to escape initial detection, possibly precipitating misdiagnosis or delay to diagnosis. Nonweight-bearing radiography may be insensitive to demonstrating the anatomical disruption of significant midfoot injuries. Weight-bearing radiographic views along with selective use of MRI and CT aid in proper identification of injury to the tarsometatarsal joints and optimal management of patients with these injuries. PMID:22530195

  17. LISFRANC FRACTURE-DISLOCATION IN A FEMALE SOCCER ATHLETE

    PubMed Central

    Ellis, Karen; Saylor-Pavkovich, Estee

    2012-01-01

    Individuals with midfoot injuries may present to physical therapists in a variety of clinical settings. The ability of the physical therapy practitioner to optimally manage the care of such an individual may be dependent on understanding the diagnostic imaging that is indicated or has been been completed. Among the potentially most debilitating midfoot injuries are Lisfranc fracture-dislocations. This case outlines the use of conventional radiology, standard computerized tomography (CT), and three-dimensional CT for differential diagnosis of Lisfranc and associated midfoot injury in a 26 year-old female recreational athlete. Her subsequent surgical and post-surgical management is briefly discussed. Physical therapists evaluating patients with suspected midfoot injuries should be cognizant of the tendency for Lisfranc injuries to escape initial detection, possibly precipitating misdiagnosis or delay to diagnosis. Nonweight-bearing radiography may be insensitive to demonstrating the anatomical disruption of significant midfoot injuries. Weight-bearing radiographic views along with selective use of MRI and CT aid in proper identification of injury to the tarsometatarsal joints and optimal management of patients with these injuries. PMID:22530195

  18. Epitaxial growth in dislocation-free strained asymmetric alloy films

    SciTech Connect

    Desai, Rashmi C.; Kim, Ho Kwon; Chatterji, Apratim; Ngai, Darryl; Chen Si; Yang Nan

    2010-06-15

    Epitaxial growth in strained asymmetric, dislocation-free, coherent, alloy films is explored. Linear-stability analysis is used to theoretically analyze the coupled instability arising jointly from the substrate-film lattice mismatch (morphological instability) and the spinodal decomposition mechanism. Both the static and growing films are considered. Role of various parameters in determining stability regions for a coherent growing alloy film is investigated. In addition to the usual parameters: lattice mismatch {epsilon}, solute-expansion coefficient {eta}, growth velocity V, and growth temperature T, we consider the alloy asymmetry arising from its mean composition. The dependence of elastic moduli on composition fluctuations and the coupling between top surface and underlying bulk of the film also play important roles. The theory is applied to group III-V films such as GaAsN, InGaN, and InGaP and to group IV Si-Ge films at temperatures below the bare critical temperature T{sub c} for strain-free spinodal decomposition. The dependences of various material parameters on mean concentration and temperature lead to significant qualitative changes.

  19. 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. PMID:27339584

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

    PubMed

    Beyerlein, I J; Hunter, A

    2016-04-28

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

  1. [Closed injuries of the extensor hood of the metacarpophalangeal joint].

    PubMed

    Ferlemann, K; Zilch, H

    1997-12-01

    Closed traumatic lesions of the extensor tendon hood of a longfinger at the metacarpophalangeal joint are rare. Surgical treatment was done in 6 cases during the last 10 years in our department; in 5 cases the dorsoradial part, in one case the dorsoulnar part of the hood was injured. The tear extended longitudinal or diagonal through the transverse fibers of the hood. Respecting the accident mechanism there have been reported tangential forces at the extensor tendon hood and forced ulnar deviation in the bended metacarpophalangeal joint. A jerky dislocation of the extensor tendon to the ulnar side of the metacarpophalangeal head during increased bending of the metacarpophalangeal joint, sometimes with ulnar abduction of the longfinger, leads usually to the diagnosis. Misdiagnoses of cases sent to our department were: "trigger finger" and "recurrent dislocation of the metacarpophalangeal joint". Once the presurgical diagnosis was "rupture of the extensor tendon" because of a permanent extension deficit in 30 degree position of the metacarpophalangeal joint. Treatment is always surgical with suture of the hood and immobilization of the metacarpophalangeal joint in extension position for 4 weeks. Conservative treatment can not heal up a tear of the extensor tendon hood. PMID:9483789

  2. 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.

  3. Patella dislocation following distal femoral replacement after bone tumour resection

    PubMed Central

    Akiyama, Toru; Kanda, Shotaro; Maeda, Akinori; Endo, Minoru; Saita, Kazuo

    2014-01-01

    We report the case of a 16-year-old girl with patella dislocation following distal femur replacement for a malignant tumour. We performed a medial plication and lateral release procedure to treat her persistent patellar dislocation after distal femur replacement following malignant tumour resection. This treatment improved the patient's gait ability dramatically. A distal femur reconstruction with a total knee arthroplasty (TKA) system for tumour resection is a frequently performed procedure. The reported incidence of patella dislocation following distal femur reconstruction with a TKA is 2.3%. However, treatment procedures for patella dislocation following a distal femur replacement after malignant tumour resection have not been studied extensively. To the best of our knowledge, this is the first English case report about patella dislocation following distal femoral replacement focusing on surgical treatment. Our experience suggests that treatment for patella dislocation following distal femur reconstruction with a TKA should be considered positively. PMID:25073529

  4. Glassy dislocation dynamics in 2D colloidal dimer crystals.

    PubMed

    Gerbode, Sharon J; Agarwal, Umang; Ong, Desmond C; Liddell, Chekesha M; Escobedo, Fernando; Cohen, Itai

    2010-08-13

    Although glassy relaxation is typically associated with disorder, here we report on a new type of glassy dynamics relating to dislocations within 2D crystals of colloidal dimers. Previous studies have demonstrated that dislocation motion in dimer crystals is restricted by certain particle orientations. Here, we drag an optically trapped particle through such dimer crystals, creating dislocations. We find a two-stage relaxation response where initially dislocations glide until encountering particles that cage their motion. Subsequent relaxation occurs logarithmically slowly through a second process where dislocations hop between caged configurations. Finally, in simulations of sheared dimer crystals, the dislocation mean squared displacement displays a caging plateau typical of glassy dynamics. Together, these results reveal a novel glassy system within a colloidal crystal. PMID:20868079

  5. Free energy of dislocations in a multi-slip geometry

    NASA Astrophysics Data System (ADS)

    Kooiman, M.; Hütter, M.; Geers, M. G. D.

    2016-03-01

    The collective dynamics of dislocations is the underlying mechanism of plastic deformation in metallic crystals. Dislocation motion in metals generally occurs on multiple slip systems. The simultaneous activation of different slip systems plays a crucial role in crystal plasticity models. In this contribution, we study the energetic interactions between dislocations on different slip systems by deriving the free energy in a multi-slip geometry. In this, we restrict ourselves to straight and parallel edge dislocations. The obtained free energy has a long-range mean-field contribution, a statistical contribution and a many-body contribution. The many-body contribution is a local function of the total dislocation density on each slip system, and can therefore not be written in terms of the net dislocation density only. Moreover, this function is a strongly non-linear and non-convex function of the density on different slip systems, and hence the coupling between slip systems is of great importance.

  6. Pattern formation in a minimal model of continuum dislocation plasticity

    NASA Astrophysics Data System (ADS)

    Sandfeld, Stefan; Zaiser, Michael

    2015-09-01

    The spontaneous emergence of heterogeneous dislocation patterns is a conspicuous feature of plastic deformation and strain hardening of crystalline solids. Despite long-standing efforts in the materials science and physics of defect communities, there is no general consensus regarding the physical mechanism which leads to the formation of dislocation patterns. In order to establish the fundamental mechanism, we formulate an extremely simplified, minimal model to investigate the formation of patterns based on the continuum theory of fluxes of curved dislocations. We demonstrate that strain hardening as embodied in a Taylor-type dislocation density dependence of the flow stress, in conjunction with the structure of the kinematic equations that govern dislocation motion under the action of external stresses, is already sufficient for the formation of dislocation patterns that are consistent with the principle of similitude.

  7. Dislocation distribution in large high-purity germanium crystal

    NASA Astrophysics Data System (ADS)

    Mei, Hao; Wang, Guojian; Mei, Dongming; Huang, Mianliang; Yang, Gang; Guan, Yutong; Cubed Collaboration

    2014-03-01

    We investigated the impacts of growth rate, time-temperature profile, thermal gradient on the dislocation distribution in large high-purity germanium crystal (12 cm in diameter) grown via Czochralski along <100>orientation. The time-temperature profiles of the crystal grown at different input power were investigated using direct measurements and computational modeling. The effect of crystallization speed on dislocation density is discussed from the context of thermal gradient during growth. Several samples from the grown crystals were used for this investigation. We measured dislocation density across the entire cross-section of the grown crystal through the microscope. By measuring and calculating the dislocation density, we were able to identify the denseness and the type of dislocation, which allows us to study how the thermal stress impacts the dislocation generation and distribution across the large grown crystals. This work is supported by DOE grant DE-FG02-10ER46709 and the state of South Dakota.

  8. Atomistic simulations of dislocation pileup: Grain boundaries interaction

    DOE PAGESBeta

    Wang, Jian

    2015-05-27

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

  9. Influence of interfacial dislocations on hysteresis loops of ferroelectric films

    NASA Astrophysics Data System (ADS)

    Li, Y. L.; Hu, S. Y.; Choudhury, S.; Baskes, M. I.; Saxena, A.; Lookman, T.; Jia, Q. X.; Schlom, D. G.; Chen, L. Q.

    2008-11-01

    We investigated the influence of dislocations, located at the interface of a ferroelectric film and its underlying substrate, on the ferroelectric hysteresis loop including the remanent polarization and coercive field using phase-field simulations. We considered epitaxial ferroelectric BaTiO3 films and found that the hysteresis loop is strongly dependent on the type and density of interfacial dislocations. The dislocations that stabilize multiple ferroelectric variants and domains reduce the coercive field, and consequently, the corresponding remanent polarization also decreases.

  10. Dislocation dynamics during the growth of silicon ribbon

    NASA Technical Reports Server (NTRS)

    Dillon, O. W., Jr.; Tsai, C. T.; De Angelis, R. J.

    1986-01-01

    The thermal viscoplastic stresses and the dislocation densities in silicon ribbon are computed for an axially changing thermal profile by using an iterative finite difference method. A material constitutive equation (Haasen-Sumino model) which involves an internal variable (mobile dislocation density) is used. The results are interpreted as showing that there is a maximum width of silicon ribbon that can be grown when viscoplasticity and dislocations are considered. This maximum width limitation does not exist if the material behavior is elastic.

  11. Crystal geometry of screw dislocation glide in tungsten nanocrystals

    NASA Astrophysics Data System (ADS)

    Sadanov, E. V.

    2015-02-01

    A zigzag pattern of low-temperature dislocation glide occurring in tungsten nanocrystals in the intersecting planes {110} and {211}, which belong to the <111> crystallographic zone, has been revealed using field ion microscopy. It has been shown that cores of 1/2[111] screw dislocations are undissociated within the limits of the resolution of the field ion microscope. It has been found experimentally that surface atoms are displaced into metastable positions in the region of the trace of screw dislocation motion.

  12. 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

  13. 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.

  14. Ultrahigh strength of dislocation-free Ni3Al nanocubes.

    PubMed

    Maaß, Robert; Meza, Lucas; Gan, Bin; Tin, Sammy; Greer, Julia R

    2012-06-25

    Individual Ni(3) Al nanocubes under pressure are investigated by comparing the compressive strength of both dislocation-free and irradiated Ni(3) Al nanocubes. The results are dicussed in light of the size-dependent and size-independent strength of face-centered cubic (fcc) nanocrystals in the framework of dislocation nucleation at free surfaces. This study sheds more light on the understanding of fundamental deformation mechanisms and size-affected strength in dislocation-free metallic nanocrystals. PMID:22454244

  15. New mechanism for dislocation blocking in strained layer epitaxial growth

    SciTech Connect

    Stach, E.A.; Schwarz, K.W.; Hull, R.; Ross, F.M.; Tromp, R.M.

    1999-09-14

    Dislocation interactions play a critical role in plasticity and heteroepitaxial strain relaxation. We use real time transmission electron microscopy observations of the interaction between threading and misfit dislocations in SiGe heterostructures to investigate interactions quantitatively. In addition to the expected long range blocking of threading segments, we observe a new short range mechanism which is significantly more effective. Simulations show that this reactive blocking occurs when two dislocations with the same Burgers vector reconnect.

  16. New mechanism for dislocation blocking in strained layer epitaxial growth

    PubMed

    Stach; Schwarz; Hull; Ross; Tromp

    2000-01-31

    Dislocation interactions play a critical role in plasticity and heteroepitaxial strain relaxation. We use real time transmission electron microscopy observations of the interaction between threading and misfit dislocations in SiGe heterostructures to investigate interactions quantitatively. In addition to the expected long-range blocking of threading segments, we observe a new short-range mechanism which is significantly more effective. Simulations show that this reactive blocking occurs when two dislocations with the same Burgers vector reconnect. PMID:11017412

  17. Edge Dislocations in Smectic-A Liquid Crystals

    NASA Astrophysics Data System (ADS)

    Ambrožič, M.; Slavinec, M.; Kralj, S.

    We study theoretically static structure and annihilation dynamics of edge dislocations in a smectic-A liquid crystal confined to a plan-parallel cell. The Landau-Ginzburg type phenomenological approach is used in terms of a complex order parameter. We investigate a structure of an isolated dislocation that is enforced by boundary conditions. We further follow the annihilation dynamics of a pair of dislocations into a defectless state.

  18. 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.

  19. Fabrication of mesoscopic floating Si wires by introducing dislocations

    NASA Astrophysics Data System (ADS)

    Motohashi, Mitsuya; Shimizu, Kazuya; Suzuki, Toshiaki; Niwa, Masaaki

    2014-12-01

    We fabricated a mesoscopic Si wire by introducing dislocations in a silicon wafer before HF anodization. The dislocations formed along the (111) crystal plane. The outline of the dislocation line was an inverted triangle. The resulting wire floated on a bridge girder and had a hybrid structure consisting of a porous layer and crystalline Si. The cross section of the wire had an inverted triangle shape. The wire formation mechanism is discussed in terms of carrier transport, crystal structure, and dislocation formation during anodization.

  20. Bilateral traumatic hip dislocation with sciatic nerve palsy.

    PubMed

    Fan, Ka Yuk; Lui, Tun Hing

    2015-01-01

    Bilateral hip dislocation is a rare condition. We report a case of traumatic bilateral hip dislocation and unilateral sciatic nerve palsy in a young woman with known idiopathic scoliosis. With prompt reduction of the dislocated hips, there was reasonable neurological recovery. There was no avascular necrosis of the femoral head or post-traumatic arthritis up to 3-year follow-up. The gender difference in incidence, as well as the predisposition of hip dislocation in scoliosis is discussed. In our case, the decreased femoral anteversion was the culprit. PMID:25809426

  1. Neglected isolated plantar dislocation of middle cuneiform : a case report

    PubMed Central

    Verma, Ashu; Sharma, Vinod Kumar; Batra, Sumit; Rohria, Mahender Singh

    2007-01-01

    Background Four cases of plantar dislocation of middle cuneiform have been reported in the english literature. All of them were fresh cases and treated with open reduction. We are reporting a case of neglected plantar dislocation of middle cuneiform which was treated with excision. Case presentation A farmer presented with a painful plantar dislocation of middle cuneiform bone after 9 months of injury. The bone was deformed and was excised by a plantar incision. It resulted in painless foot with no disability. Conclusion The neglected plantar dislocated middle cuneiform bone becomes deformed due to repeated weight bearing. The gap gets filled with Fibrous tissue. Excision of the cuneiform gives good results. PMID:17229316

  2. Dislocation dynamics modelling of radiation damage in thin films

    NASA Astrophysics Data System (ADS)

    Ferroni, Francesco; Tarleton, Edmund; Fitzgerald, Steven

    2014-06-01

    Transmission electron microscopy is a key tool for the extraction of information on radiation damage, the understanding of which is critical for materials development for nuclear fusion and fission reactors. Dislocations in TEM samples are subject to strong image forces, owing to the nanometric sample thicknesses, which may introduce artifacts in the damage analysis. Using dislocation dynamics, we elucidate the roles played by dislocation-surface interactions, dislocation-dislocation interactions and self-interactions due to climb for loop types observed in TEM. Comparisons with analytic solutions for a dislocation loop and an edge dislocation in a half-space are included, and the relationship between glide force and loop tilt examined. The parameters for convergence of the zero-traction boundary conditions are obtained, after which the evolution of dislocation structures in a thin film is studied. It is found that three main length scales govern the physical processes: the image force is governed by the distance of the loop from the surface and scales with the film thickness; the glide force is governed by the image stress as well as the loop-loop interaction stress which is in turn governed by the loop spacing L\\sim 1/\\sqrt{\\rho} , where ρ is the loop density; finally, the climb force depends on the loop size. The three forces compete and their relative magnitudes define the evolution pathway of the dislocation structure.

  3. Temperature and strain-rate dependence of surface dislocation nucleation.

    PubMed

    Zhu, Ting; Li, Ju; Samanta, Amit; Leach, Austin; Gall, Ken

    2008-01-18

    Dislocation nucleation is essential to the plastic deformation of small-volume crystalline solids. The free surface may act as an effective source of dislocations to initiate and sustain plastic flow, in conjunction with bulk sources. Here, we develop an atomistic modeling framework to address the probabilistic nature of surface dislocation nucleation. We show the activation volume associated with surface dislocation nucleation is characteristically in the range of 1-10b3, where b is the Burgers vector. Such small activation volume leads to sensitive temperature and strain-rate dependence of the nucleation stress, providing an upper bound to the size-strength relation in nanopillar compression experiments. PMID:18232884

  4. 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.

  5. Internal stresses in a homogenized representation of dislocation microstructures

    NASA Astrophysics Data System (ADS)

    Schmitt, Severin; Gumbsch, Peter; Schulz, Katrin

    2015-11-01

    To develop a continuum theory based on the evolution of dislocation microstructures, two challenges have to be resolved: the correct representation of the kinematics of dislocation motion in terms of dislocation density and the formulation of a mobility law reflecting an effective description of the physical behavior of the discrete many-body problem. Kröner's classical continuum theory has inspired different approaches to model plasticity based on the motion of dislocations. Amongst them, the Continuum Dislocation Dynamics (CDD) theory was formulated as a generalization of the classical theory. The CDD theory allows for a continuous representation of the evolution of dislocation microstructures and is found to be kinematically complete. Here, a numerical formulation of the CDD theory is presented and constitutive laws for the incorporation of dislocation interactions are derived based on the representation of the dislocation microstructure in two dimensions. An error measure is introduced to analyze the constitutive law and the results are compared to discrete dislocation dynamics simulations. Important aspects for the implementation of a 3D theory are discussed.

  6. Orientation dependence of shock induced dislocations in Tantalum single crystals

    NASA Astrophysics Data System (ADS)

    Pang, Bo; Jones, I.; Chiu, Yulung; Millett, J.; Whiteman, Glenn; Bourne, N.

    2013-06-01

    Shock wave deformation of monocrystalline tantalum to a pressure of 6.2 GPa and duration of 1.7 μs generates profuse dislocations. Three orientations (100),(110),(111) were tested to examine the orientation dependence of the dislocation generation. The dislocations were characterised by transmission electron microscopy. The difference in the Burgers vectors of the primary dislocations in the specimens with different orientations showed a distinct anisotropy and will be discussed in light of the models of slip behaviour in one-dimensional strain (Smith 1958) and (Meyers 1978). The front and rear surfaces of the specimens were both investigated to examine the effects of wave duration.

  7. Screw dislocation in a two-phase isotropic thin film

    NASA Astrophysics Data System (ADS)

    Chu, S. N. G.

    1982-04-01

    By using the complex potential and conformal mapping techniques, the stress field of a straight screw dislocation lying parallel to the surface of a two-phase isotropic thin film of equal thickness in each phase and a welded interface is analyzed. The solution, when reduced to a single-phase thin film, is in agreement with that derived by Liebfried and Dietze using an infinite array of image dislocations. The presence of a second phase is found to increase the magnitude of the stress components for the screw dislocation except for τxz near the interface where the effect is the reverse. The image force on the dislocation near the interface can be attractive or repulsive depending upon whether the dislocation is situated in the hard or soft phase. In the case where the dislocation is situated in the soft phase, the total image force tends to drive the screw dislocation to the surface. Furthermore, the screw dislocation is found to be unstable at the interface. The elastic solution for an interfacial dislocation becomes a special case.

  8. 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.

  9. Congenital dislocation of the patella – clinical case☆

    PubMed Central

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

    2015-01-01

    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. PMID:26962496

  10. Dislocation luminescence in GaN single crystals under nanoindentation

    NASA Astrophysics Data System (ADS)

    Huang, Jun; Xu, Ke; Fan, Ying Min; Wang, Jian Feng; Zhang, Ji Cai; Ren, Guo Qiang

    2014-12-01

    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.

  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. PMID:24010425

  12. Combined medial column primary arthrodesis, middle column open reduction internal fixation, and lateral column pinning for treatment of Lisfranc fracture-dislocation injuries.

    PubMed

    Boffeli, Troy J; Pfannenstein, Ryan R; Thompson, Jonathan C

    2014-01-01

    Lisfranc fracture-dislocation can be a devastating injury with significant long-term sequelae, including degenerative joint disease, progressive arch collapse, and chronic pain that can be potentiated if not effectively treated. We present a case to demonstrate our preferred surgical approach, consisting of combined medial column primary arthrodesis, middle column open reduction internal fixation, and lateral column pinning, with the primary goal of minimizing common long-term complications associated with Lisfranc injuries. We present the case of a typical patient treated according to this combined surgical approach to highlight our patient selection criteria, rationale, surgical technique, and operative pearls. A 36-year-old male who had sustained a homolateral Lisfranc fracture-dislocation injury after falling from a height initially underwent fasciotomy for foot compartment syndrome. The subsequent repair 16 days later involved primary first tarsometatarsal joint fusion, open reduction internal fixation of the second and third tarsometatarsal joints, and temporary pinning of the fourth and fifth tarsometatarsal joints. He progressed well postoperatively, exhibiting an American College of Foot and Ankle Surgeons forefoot score of 90 of 100 at 1 year after surgery with no need for subsequent treatment. Lisfranc fracture-dislocations often exhibit primary dislocation to the medial column and are conducive to arthrodesis to stabilize the tarsometatarsal complex. The middle column frequently involves comminuted intra-articular fractures and will often benefit from less dissection required for open reduction internal fixation instead of primary fusion. We propose that this surgical approach is a viable alternative technique for primary treatment of Lisfranc fracture-dislocation injuries. PMID:24846158

  13. AC power systems handbook

    SciTech Connect

    Whitaker, J.

    1991-01-01

    Transient disturbances are what headaches are made of. Whatever you call them-spikes, surges, are power bumps-they can take your equipment down and leave you with a complicated and expensive repair job. Protection against transient disturbances is a science that demands attention to detail. This book explains how the power distribution system works, what can go wrong with it, and how to protect a facility against abnormalities. system grounding and shielding are covered in detail. Each major method of transient protection is analyzed and its relative merits discussed. The book provides a complete look at the critical elements of the ac power system. Provides a complete look at the ac power system from generation to consumption. Discusses the mechanisms that produce transient disturbances and how to protect against them. Presents diagrams to facilitate system design. Covers new areas, such as the extent of the transient disturbance problem, transient protection options, and stand-by power systems.

  14. Proceedings of the 1994 ASME/IEEE joint railroad conference

    SciTech Connect

    Hawthorne, K.L.; Hill, J.R.

    1994-12-31

    The proceedings contains 22 papers from the IEEE/ASME Joint Railroad Conference. Topics discussed include flange bearing crossing frogs; rapid transit; vehicle on-board computer systems; total transport system control functions; automated train dispatching system; wheel thermal damage limits; AC propulsion; AC traction drives; electric power supplies; failure detection and identification; cargo transportation; and critical speed for railroad vehicles. Papers within the scope of the data base have been processed separately.

  15. 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

  16. [Has the duration of cast fixation after shoulder dislocations an influence on the frequency of recurrent dislocation? (author's transl)].

    PubMed

    Ehgartner, K

    1977-08-26

    102 primary shoulder dislocations have been evaluated. Some were retained in a Velpeau bandage reinforced with plaster immediately after reposition for three weeks, others were treated with a sling or tube gauze only. The frequency of recurrent dislocation in both groups was compared. It could be demonstrated that the results were equal for both groups. We conclude that fixation with Velpeau Sling and cast reinforcement does not significantly influence the occurrence of recurrent dislocations. PMID:907550

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

    PubMed Central

    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. PMID:26229781

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

    PubMed Central

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

    2015-01-01

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

  19. Pseudoclimb and dislocation dynamics in superplastic nanotubes.

    PubMed

    Ding, Feng; Jiao, Kun; Wu, Mingqi; Yakobson, Boris I

    2007-02-16

    Plastic relaxation of carbon nanotubes under tension and at high temperature is described in terms of dislocation theory and with atomistic computer simulations. It is shown how the glide of pentagon-heptagon defects and a particular type of their pseudoclimb, with the atoms directly breaking out of the lattice, work concurrently to maintain the tube perfection. Derived force diagram quantifies the balance between these mechanisms, while simulations show both helical and longitudinal movement of the kinks, in agreement with the forces and with experimental observations. PMID:17359035

  20. Dislocation Mechanics of High-Rate Deformations

    NASA Astrophysics Data System (ADS)

    Armstrong, Ronald W.; Li, Qizhen

    2015-10-01

    Four topics associated with constitutive equation descriptions of rate-dependent metal plastic deformation behavior are reviewed in honor of previous research accomplished on the same issues by Professor Marc Meyers along with colleagues and students, as follow: (1) increasing strength levels attributed to thermally activated dislocation migration at higher loading rates; (2) inhomogeneous adiabatic shear banding; (3) controlling mechanisms of deformation in shock as compared with shock-less isentropic compression experiments and (4) Hall-Petch-based grain size-dependent strain rate sensitivities exhibited by nanopolycrystalline materials. Experimental results are reviewed on the topics for a wide range of metals.

  1. [Acute perilunar dislocations: algorithm for treatment].

    PubMed

    Towfigh, H

    2001-01-01

    In most cases, perilunar dislocations of the wrist are caused by high speed accidents. Usually these injuries occur by a fall on the dorsiflexed superextension of the hand. The instability caused by injuries of various erticular structures (ligament, bone) show various developmental stages. Clinical symptoms are reduced and painful movement, instability of the carpus, snapping and swelling. The diagnosis is established by X-ray, cinematography, arthrography MRT or CT. Perilunar instability with or without associated fractures and particularly de Quervain must be reduced and treated operatively including suture of the ligament and stabilization of the fracture. PMID:11824286

  2. 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. PMID:24788187

  3. [Concomitant diseases in primary joint hypermobility syndrome].

    PubMed

    Skoumal, Martin; Haberhauer, Günther; Mayr, Hans

    2004-10-15

    The primary joint hypermobility syndrome (pJH) is an overlap disorder of connective-tissue dysplasias, which incorporates features seen in the Marfan syndromes (MFS), Ehlers-Danlos syndromes (EDS), and osteogenesis imperfecta. Patients with pJH usually present arthralgia, back pain, soft-tissue lesions, recurrent joint dislocation, or subluxation. Extraarticular features may include, e. g., striae cutis, keratoconus, easy bruising, mitral valve prolapse, aortic incompetence, aneurysms, pneumothorax, hernia, urinary incontinence, and pelvic floor prolapse. Due to the high frequency of critical dissection and rupture, the early recognition of rare life-threatening complications such as dilatation of the aortic root and aneurysms is important. Therefore, patients (and their family members) with pJH should also be examined for life-threatening features seen in MFS and EDS. PMID:15490074

  4. The sternocostoclavicular joint: normal and abnormal features.

    PubMed

    Le Loët, Xavier; Vittecoq, Olivier

    2002-03-01

    Many physicians are unfamiliar with the characteristics of the sternocostoclavicular joint (SCCJ). Disorders of the SCCJ, although common, frequently escape recognition. Computed tomography (CT) with thin slices and no gap is at presentthe best means of investigating the SCCJ. CTfeatures in normal subjects have been described in detail; some are misleading. The most common SCCJ disorder is degenerative disease manifesting as osteoarthritis or as periarticular lesions causing antero-medial dislocation of the clavicle. Septic arthritis is the most severe disorder and can lead to mediastinitis. All inflammatory joint diseases, including spondyloarthropathies, can affect the SCCJ. SCCJ involvement is a typical component of the osteoarticular manifestations seen in patients with palmoplantar pustulosis. PMID:12027306

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

    PubMed

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

    2016-02-01

    Joint fractures of the fingers often entail operative interventions in contrast to extra-articular fractures. These types of fracture are inclined to dislocate in addition to the actual fracture. The proximal interphalangeal (PIP) joint in particular often shows comminuted fractures due to the long leverage of the finger and a relatively small diameter of the joint. The clinical examination, X-ray diagnostics and if necessary computed tomography allow the classification into stable and unstable fractures. Unstable fractures must be treated by surgical reduction and fixation. A multitude of operative techniques are available for these mostly complicated fractures. The foremost goal is a stable osteosynthesis of the fracture with repositioning of the dislocation, which enables early physiotherapy in order to prevent tendon adhesion and contracture. This article presents the different types of PIP joint fractures, their specific surgical treatment and postoperative treatment regimens. PMID:26826026

  6. Collective overcoming of point defects by dislocations in the dynamic region

    NASA Astrophysics Data System (ADS)

    Malashenko, V. V.

    2014-08-01

    A mechanism of collective overcoming of point defects by dislocations during the over-barrier slip has been proposed. It has been shown that the interaction between dislocations promotes the overcoming of point defects at a high dislocation density.

  7. 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.

  8. Implicit integration methods for dislocation dynamics

    DOE PAGESBeta

    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 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

  9. 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.

  10. Efficient time integration in dislocation dynamics

    NASA Astrophysics Data System (ADS)

    Sills, Ryan B.; Cai, Wei

    2014-03-01

    The efficiencies of one implicit and three explicit time integrators have been compared in line dislocation dynamics simulations using two test cases: a collapsing loop and a Frank-Read (FR) source with a jog. The time-step size and computational efficiency of the explicit integrators is shown to become severely limited due to the presence of so-called stiff modes, which include the oscillatory zig-zag motion of discretization nodes and orientation fluctuations of the jog. In the stability-limited regime dictated by these stiff modes, the implicit integrator shows superior efficiency when using a Jacobian that only accounts for short-range interactions due to elasticity and line tension. However, when a stable dislocation dipole forms during a jogged FR source simulation, even the implicit integrator suffers a substantial drop in the time-step size. To restore computational efficiency, a time-step subcycling algorithm is tested, in which the nodes involved in the dipole are integrated over multiple smaller, local time steps, while the remaining nodes take a single larger, global time step. The time-step subcycling method leads to substantial efficiency gain when combined with either an implicit or an explicit integrator.

  11. 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. PMID:26229839

  12. Extensor Mechanism Disruption in Knee Dislocation.

    PubMed

    O'Malley, Michael; Reardon, Patrick; Pareek, Ayoosh; Krych, Aaron; Levy, Bruce A; Stuart, Michael J

    2016-05-01

    Disruption of the knee extensor mechanism is a challenging injury with no clear consensus on optimal treatment. Although rare in the setting of knee dislocations, these injuries should not be overlooked. Acute, complete rupture of either the quadriceps or patellar tendon necessitates primary repair with or without augmentation. Surgical management may also be required in the setting of a partial tear if a significant extensor lag is present or nonoperative treatment has failed. Tendon augmentation is used during primary repair if the native tissue is inadequate or after a failed primary repair. The purpose of this study is to evaluate extensor mechanism disruption incidence, injury patterns, associated injuries, and surgical options, including a novel tendon augmentation technique. This procedure consists of primary patellar or quadriceps tendon repair with semitendinosus autograft augmentation utilizing a distal or proximal patellar socket. Advantages of repair with tendon augmentation include accelerated rehabilitation, decreased risk of patellar fracture from transverse or longitudinal bone tunnels, and less hardware complications. We recommend consideration of this technique for selected cases of acute extensor mechanism disruption in the setting of tibiofemoral dislocation. PMID:26636488

  13. 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.

  14. CT evaluation of tarsometatarsal fracture-dislocation injuries

    SciTech Connect

    Goiney, R.C.; Connell, D.G.; Nichols, D.M.

    1985-05-01

    Fracture-dislocation in the tarsometatarsal region (Lisfranc) may be subtle and difficult to recognize on standard radiographic projections. Computed tomography (CT) was used to study the normal anatomy of the forefoot and to evaluate three patients with suspected tarsometatarsal fracture dislocation. The advantages of CT in the evaluation of forefoot trauma are emphasized.

  15. 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.

  16. 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.

  17. A Case of Simultaneous Bilateral Anterior Shoulder Dislocation

    PubMed Central

    Patil, Mallanagouda N

    2013-01-01

    Introduction: Anterior dislocation of shoulder is commonest dislocation one encounters in day to day Orthopaedic practice. But bilateral shoulder dislocations are relatively uncommon frequently posterior and secondary to violent muscle contraction. Simultaneous bilateral anterior dislocations of shoulder following trauma is rare occurrence. Case Report: 35 year old male presented to emergency department with history fall by tripping on a stone (fall on outstretched hand). He complained of pain and difficulty in moving both the shoulders. On clinical examination, patient's both upper limbs were abducted and externally rotated. Bilaterally shoulder contour was lost with flattening. Other classical signs of shoulder dislocation viz, Bryants test, Callway sign, Hamilton's ruler test were positive. Diagnosis was confirmed on X rays. Both shoulders were reduced in emergency operation theater under general anaesthesia by Kocher's method and were immobilised in sling. Conclusion: Though bilateral shoulder dislocations are commonly posterior, usually either secondary to convulsions or electric shock, anterior dislocation has to be kept in mind , especially in post traumatic injuries. This bilateral dislocation also presents with practical problems immobilization and day to day care of patients. PMID:27298905

  18. 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)

  19. 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.

  20. Moment tensors of a dislocation in a porous medium

    NASA Astrophysics Data System (ADS)

    Wang, Zhi; Hu, Hengshan

    2016-06-01

    A dislocation can be represented by a moment tensor for calculating seismic waves. However, the moment tensor expression was derived in an elastic medium and cannot completely describe a dislocation in a porous medium. In this paper, effective moment tensors of a dislocation in a porous medium are derived. It is found that the dislocation is equivalent to two independent moment tensors, i.e., the bulk moment tensor acting on the bulk of the porous medium and the isotropic fluid moment tensor acting on the pore fluid. Both of them are caused by the solid dislocation as well as the fluid-solid relative motion corresponding to fluid injection towards the surrounding rocks (or fluid outflow) through the fault plane. For a shear dislocation, the fluid moment tensor is zero, and the dislocation is equivalent to a double couple acting on the bulk; for an opening dislocation or fluid injection, the two moment tensors are needed to describe the source. The fluid moment tensor only affects the radiated compressional waves. By calculating the ratio of the radiation fields generated by unit fluid moment tensor and bulk moment tensor, it is found that the fast compressional wave radiated by the bulk moment tensor is much stronger than that radiated by the fluid moment tensor, while the slow compressional wave radiated by the fluid moment tensor is several times stronger than that radiated by the bulk moment tensor.