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Sample records for anterior scj instability

  1. Anterior instability in the throwing shoulder.

    PubMed

    Savoie, Felix H; O'Brien, Michael J

    2014-06-01

    The disabled throwing shoulder is a multifactorial problem. Laxity of the glenohumeral joint is necessary to achieve a satisfactory velocity. Normal wear and tear with throwing may convert this normal amount of excessive translation into instability. Instability in the throwing athlete manifests itself in 2 forms: traumatic anterior instability that happens to occur in a throwing athlete and excessive anterior subluxation because of overuse that occurs in conjunction with the disabled throwing shoulder. In most cases, it is difficult to determine by physical examination or imaging how much laxity is too much; therefore, the managing physician should always err on the side of caution. A trial of rest and rehabilitation should always be attempted before any consideration of surgery. The multifactorial issues in the disabled throwing athlete should be corrected during this phase of treatment, including assessment and treatment of hip abnormalities, restoration of satisfactory core strength, correction of scapular dyskinesis, and an evaluation and correction of any biomechanical abnormalities in the throwing mechanism. Surgical management of anterior instability in the throwing shoulder depends on the mechanism of injury. The traumatic anterior instability patient is managed by acute surgical repair without a shift, utilizing mattress sutures to prevent suture chondromalacia on the humeral head or glenoid. The anterior laxity management centers on the posterior superior labrum, although occasionally the anterior labrum or capsule may be involved as well. Overall, symptomatic anterior instability is less common in the throwing shoulder. Jobe and colleagues are credited with the first successful technique for the correction of anterior instability in the throwing athlete, the anterior capsulolabral reconstruction by a subscapularis split. The success of this technique paved the way for the adoption of the current arthroscopic techniques that are utilized to correct

  2. Arthroscopic Findings in Anterior Shoulder Instability

    PubMed Central

    Hantes, Michael; Raoulis, Vasilios

    2017-01-01

    Background: In the last years, basic research and arthroscopic surgery, have improved our understanding of shoulder anatomy and pathology. It is a fact that arthroscopic treatment of shoulder instability has evolved considerably over the past decades. The aim of this paper is to present the variety of pathologies that should be identified and treated during shoulder arthroscopy when dealing with anterior shoulder instability cases. Methods: A review of the current literature regarding arthroscopic shoulder anatomy, anatomic variants, and arthroscopic findings in anterior shoulder instability, is presented. In addition, correlation of arthroscopic findings with physical examination and advanced imaging (CT and MRI) in order to improve our understanding in anterior shoulder instability pathology is discussed. Results: Shoulder instability represents a broad spectrum of disease and a thorough understanding of the pathoanatomy is the key for a successful treatment of the unstable shoulder. Patients can have a variety of pathologies concomitant with a traditional Bankart lesion, such as injuries of the glenoid (bony Bankart), injuries of the glenoid labrum, superiorly (SLAP) or anteroinferiorly (e.g. anterior labroligamentous periosteal sleeve avulsion, and Perthes), capsular lesions (humeral avulsion of the glenohumeral ligament), and accompanying osseous-cartilage lesions (Hill-Sachs, glenolabral articular disruption). Shoulder arthroscopy allows for a detailed visualization and a dynamic examination of all anatomic structures, identification of pathologic findings, and treatment of all concomitant lesions. Conclusion: Surgeons must be well prepared and understanding the normal anatomy of the glenohumeral joint, including its anatomic variants to seek for the possible pathologic lesions in anterior shoulder instability during shoulder arthroscopy. Patient selection criteria, improved surgical techniques, and implants available have contributed to the enhancement of

  3. Natural History of Anterior Shoulder Instability

    PubMed Central

    Carpinteiro, Eduardo Palma; Barros, Andre Aires

    2017-01-01

    Background: The shoulder is the most complex joint in the body. The large freedom of motion in this joint is the main cause of instability. Instability varies in its degree, direction, etiology and volition and there is a large spectrum of conditions. Methods: Based on literature research and also in our own experience, we propose to elucidate the reader about the natural history of instability and its importance for the appropriate management of this pathology, by answering the following questions: What happens in the shoulder after the first dislocation? Which structures suffer damage? Who are the patients at higher risk of recurrence? How does the disease evolve without treatment? Will surgical treatment avoid future negative outcomes and prevent degenerative joint disease? Who should we treat and when? Results: 80% of anterior-inferior dislocations occur in young patients. Recurrent instability is common and multiple dislocations are the rule. Instability is influenced by a large number of variables, including age of onset, activity profile, number of episodes,delay between first episode and surgical treatment. Conclusion: Understanding the disease and its natural evolution is determinant to decide the treatment in order to obtain the best outcome. It is crucial to identify the risk factors for recurrence. Delay in surgical treatment, when indicated, leads to worse results. Surgical technique should address the type and severity of both soft tissue and bone lesions, when present.

  4. Natural History of Anterior Shoulder Instability.

    PubMed

    Carpinteiro, Eduardo Palma; Barros, Andre Aires

    2017-01-01

    The shoulder is the most complex joint in the body. The large freedom of motion in this joint is the main cause of instability. Instability varies in its degree, direction, etiology and volition and there is a large spectrum of conditions. Based on literature research and also in our own experience, we propose to elucidate the reader about the natural history of instability and its importance for the appropriate management of this pathology, by answering the following questions: What happens in the shoulder after the first dislocation? Which structures suffer damage? Who are the patients at higher risk of recurrence? How does the disease evolve without treatment? Will surgical treatment avoid future negative outcomes and prevent degenerative joint disease? Who should we treat and when? 80% of anterior-inferior dislocations occur in young patients. Recurrent instability is common and multiple dislocations are the rule. Instability is influenced by a large number of variables, including age of onset, activity profile, number of episodes,delay between first episode and surgical treatment. Understanding the disease and its natural evolution is determinant to decide the treatment in order to obtain the best outcome. It is crucial to identify the risk factors for recurrence. Delay in surgical treatment, when indicated, leads to worse results. Surgical technique should address the type and severity of both soft tissue and bone lesions, when present.

  5. [Anterior shoulder instability--the current situation].

    PubMed

    Schofer, M D; Diehl, A; Theisen, C; Timmesfeld, N; Heyse, T J; Fuchs-Winkelmann, S; Efe, T

    2010-01-01

    The aim of the study was to survey the current state of the conservative and operative treatment of anterior shoulder instability and its rehabilitation in German hospitals. A previously evaluated online questionnaire was sent out to all German hospitals with orthopaedic or trauma surgery departments. The Federal Statistical Office's hospital list was the basis for the selection of hospitals. The questions referred to the year 2007. The survey, including 3 reminders, was conducted over 3 months. The questionnaire consisted of 6 response categories: always (100%), almost always (99-81%), predominantly (80-51%), rarely (50-21%), almost never (20-1%) and never (0%). The response rate was 41% and 67% of these had carried out shoulder stabilisations. In total, 99.2% of the 67% were evaluable. The proportion of shoulder surgery was 8.4% of the total number of operations. Shoulder stabilisations represented 10.6% of these operations. A specialised shoulder department existed in 22.9%. Conservative treatment was carried out with an immobilisation of the arm "predominantly", "almost always" and "always" for internal rotation in 70.8% and in 23.4% for external rotation. The shoulders were "predominantly", "almost always" and "always" stabilised in an arthroscopic technique in 68.2% and in an open one in 31.8% of the clinics. With 92.9%, the Bankart repair was the most common operation. Shoulder instability was principally treated with the arthroscopic technique, regardless of the care level and department and is considered the best surgical technique. Physiotherapy was prescribed "always" and "almost always" in 99.3%. The rate of reluxation after conservative treatment was estimated at 35.5%, after operative open anterior shoulder stabilisation at 9.1% and after arthroscopic shoulder stabilization at 10.6%. Nevertheless, 49.4% of respondents expected the best results after arthroscopic treatment. Participants, who mainly applied the arthroscopic technique, expected a lower

  6. Mini-Open Latarjet Procedure for Recurrent Anterior Shoulder Instability

    PubMed Central

    Mercier, Numa; Saragaglia, Dominique

    2011-01-01

    Anterior shoulder instability is a common problem. The Latarjet procedure has been advocated as an option for the treatment of anteroinferior shoulder instability. The purpose of this paper is to explain our surgical procedure titled “Mini-open Latarjet Procedure.” We detailed patient positioning, skin incision, subscapularis approach, and coracoid fixation. Then, we reviewed the literature to evaluate the clinical outcomes of this procedure. PMID:22191039

  7. Arthroscopic stabilization procedures for recurrent anterior shoulder instability.

    PubMed

    Yahiro, M A; Matthews, L S

    1989-11-01

    Anterior shoulder instability is a common and functionally disabling problem in young athletes. The goal in treatment of this condition is a stable, yet mobile, joint. Current methods now being utilized in the arthroscopic stabilization of the anterior shoulder include staple capsulorrhaphy, removable rivet capsulorrhaphy, cannulated screw fixation, and the transglenoid suture technique. These techniques and the clinical experience with each are reviewed, with an emphasis on providing stability, improving function, and allowing earlier rehabilitation in the unstable shoulder of the athlete.

  8. Arthroscopic Management of Anterior, Posterior, and Multidirectional Shoulder Instabilities.

    PubMed

    Field, Larry D; Ryu, Richard K N; Abrams, Jeffrey S; Provencher, Matthew

    2016-01-01

    Arthroscopic shoulder stabilization offers several potential advantages compared with open surgery, including the opportunity to more accurately evaluate the glenohumeral joint at the time of diagnostic assessment; comprehensively address multiple pathologic lesions that may be identified; and avoid potential complications unique to open stabilization, such as postoperative subscapularis failure. A thorough understanding of normal shoulder anatomy and biomechanics, along with the pathoanatomy responsible for anterior, posterior, and multidirectional shoulder instability patterns, is very important in the management of patients who have shoulder instability. The treating physician also must be familiar with diagnostic imaging and physical examination maneuvers that are required to accurately diagnose shoulder instability.

  9. Effect of bone loss in anterior shoulder instability

    PubMed Central

    Garcia, Grant H; Liu, Joseph N; Dines, David M; Dines, Joshua S

    2015-01-01

    Anterior shoulder instability with bone loss can be a difficult problem to treat. It usually involves a component of either glenoid deficiency or a Hill-Sachs lesion. Recent data shows that soft tissue procedures alone are typically not adequate to provide stability to the shoulder. As such, numerous surgical procedures have been described to directly address these bony deficits. For glenoid defects, coracoid transfer and iliac crest bone block procedures are popular and effective. For humeral head defects, both remplissage and osteochondral allografts have decreased the rates of recurrent instability. Our review provides an overview of current literature addressing these treatment options and others for addressing bone loss complicating anterior glenohumeral instability. PMID:26085984

  10. Treatment of osseous defects associated with anterior shoulder instability.

    PubMed

    Lynch, Joseph R; Clinton, Jeremiah M; Dewing, Christopher B; Warme, Winston J; Matsen, Frederick A

    2009-01-01

    Bone loss of the glenoid and/or humerus is a common consequence of traumatic anterior shoulder instability and can be a cause of recurrent instability after a Bankart repair. Accurate characterization of the size and location of osseous defects associated with traumatic instability is important when planning treatment. Open or arthroscopic soft tissue repairs are usually sufficient when less than 25% of the width of the glenoid bone has been lost. Bone replacement techniques may be necessary when glenoid bone loss is greater than 25% of the glenoid width. Glenoid bone restoration techniques include the use of a tricortical iliac crest graft or the transfer of the coracoid process to the area of glenoid deficiency. Bone grafting becomes a strong consideration when soft tissue repairs have failed to restore stability. Treatment of these severe defects may be followed by osteoarthritis. The destabilizing effects of anterior glenoid bone defects are compounded by concurrent defects of the posterior-lateral humeral head, commonly known as Hill-Sachs lesions, which can engage the glenoid defect. Large humeral head defects can be treated by transhumeral bone grafting techniques or osteoarticular allograft reconstruction. Prosthetic replacement of the proximal humerus is considered for humeral head defects involving more than 40% of the articular surface. Understanding the importance of humeral and glenoid bone deficiencies may help guide the treatment of recurrent anterior glenohumeral instability.

  11. FUNCTIONAL ASSESSMENT OF ARTHROSCOPIC REPAIR FOR RECURRENT ANTERIOR SHOULDER INSTABILITY

    PubMed Central

    de Almeida Filho, Ildeu Afonso; de Castro Veado, Marco Antônio; Fim, Márcio; da Silva Corrêa, Lincoln Vargas; de Carvalho Junior, Antônio Enéas Rangel

    2015-01-01

    Objective: To clinically and radiologically evaluate patients who underwent arthroscopic surgical treatment for anterior shoulder instability by means of the Bankart technique, using metal anchors. Methods: This was a retrospective study on 49 patients who underwent arthroscopic repair of anterior shoulder instability between 2002 and 2007. The patients were evaluated using the Carter-Rowe score and the Samilson and Prieto classification. The mean age at the time of surgery was 30 years. The mean length of follow-up was 42.7 months (ranging from 18 to 74). 85% of the patients were male. Results: The mean Carter-Rowe score was 83 points (ranging from 30 to 100) including 31 excellent results, 7 good, 3 fair and 8 poor. Recurrent dislocation was observed in 16% (8 patients), and 37.5% of them were of traumatic origin. Joint degeneration was present in 32.5% of the cases, including 5 cases of grade 1, 6 cases of grade 2 and 2 cases of grade 3. The average loss of external rotation was 12° and the loss of anterior elevation was 8°. There was a statistically significant relationship (p < 0.05) between arthritis and age at first dislocation, age at surgery and crackling. 92% of the patients reported high degrees of satisfaction after the procedure. Among the complications, there were two cases of stiff shoulder, one patient with prominence of the synthesis material and one case of anchor loosening. Conclusion: Arthroscopic repair of anterior shoulder instability using metal anchors was shown to be effective, with a low complication rate. PMID:27042624

  12. Stress radiography for clinical evaluation of anterior shoulder instability.

    PubMed

    Park, Jin-Young; Kim, Youngbok; Oh, Kyung-Soo; Lim, Hwa-Kyung; Kim, Joo-Yong

    2016-11-01

    The purpose of this study was to examine the validity of stress radiography using the Telos GA-IIE as a clinical methodology to evaluate shoulder instability. On 36 anterior shoulder dislocators and 23 uninjured volunteers, 4 types of stress radiographs were captured while applying 15 daN of force anteriorly (AER0 and AER60) and posteriorly (PER0 and PER60) at 2 different positions: (1) 90° of abduction combined with 0° external rotation and (2) 90° of abduction combined with 60° external rotation. The results of the anterior drawer test and of the same test under anesthesia were correlated. AER0 and AER60 from the affected shoulder revealed significantly larger displacement than on the normal side (P < .05), and all 4 radiographs from the affected joints demonstrated significantly larger displacement (P < .05) than in the volunteers. Among the 4 types of radiographs, AER0 and AER60 showed significantly higher displacement in the patients (P < .001), whereas there were no differences in the volunteers (P = .167). The results of the anterior drawer test positively correlated to AER60 (Pearson correlation coefficient [PCC] = 0.453; P = .005) and AER0 (PCC = 0.529; P = .001), and those of examination under anesthesia weakly correlated to AER60 (PCC = 0.287; P = .264) but highly correlated to AER0 (PCC = 0.695; P = .002). Stress radiographs on the affected shoulder frequently correlated with physical examinations, and the displacement of >3 mm on AER0 suggests anterior instability. Copyright © 2016 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Elsevier Inc. All rights reserved.

  13. Microperforation prolotherapy: a novel method for successful nonsurgical treatment of atraumatic spontaneous anterior sternoclavicular subluxation, with an illustrative case.

    PubMed

    Stein, Alvin; McAleer, Scott; Hinz, Marty

    2011-01-01

    Surgical repair of an atraumatic spontaneous anterior subluxation of the sternoclavicular joint (herein referred to as the "SCJ") is often associated with poor outcome expectations. With traditional treatment, successful conservative therapy usually incorporates major lifestyle alterations. This manuscript discusses a novel approach known as "microperforation prolotherapy". To illustrate the technique, the care of a patient who benefitted from this treatment is reviewed. To present a novel form of treatment with an illustrative case that demonstrates the potential efficacy of microperforation prolotherapy of the SCJ. A novel approach to treatment of bilateral subluxation of the sternoclavicular joint with microperforation prolotherapy is discussed. The clinical course of a 21-year-old male with bilateral subluxation of the SCJ, which seriously hampered the patient's athletic and daily living activities, is used as a backdrop to the discussion. Following microperforation prolotherapy, the instability of the SCJ was replaced by full stability, complete range of motion, and the opportunity to engage in all of the athletic endeavors previously pursued. There is no scar or other cosmetic defect resulting from the treatment received. Anterior sternoclavicular joint subluxation has a poor record of complete recovery with surgical procedures or conservative measures with regard to providing restoration of full lifestyle function. This manuscript documents a novel microperforation prolotherapy treatment that induced healing and restored full stability to the ligament structures responsible for the condition in a completely safe and effective fashion, allowing the patient to resume full lifestyle activities without restriction. The exceptional response to treatment noted here is encouragement for further studies.

  14. [Bristow-Latarjet Technique for anterior glenohumeral instability].

    PubMed

    Jiménez, I; Marcos-García, A; Medina, J; Muratore-Moreno, G; Caballero-Martel, J

    2016-01-01

    In treatment of anterior shoulder instability, many surgical techniques have been described, all of them with advantages and disadvantages. Our goal is to study the half term results on patients that underwent open Bristow-Latarjet surgery considering the preoperative ISIS value. This is a retrospective study of 33 patients which underwent open Bristow-Latarjet surgery in our center between 2005 and 2012. Average age of 33.2 years and follow up of 75 months. Results were taken by Rowe and Constant scores, DASH questionnaire and we also recorded a subjective assessment of the result by each patient. No recurrence was reported. No reoperations. Mean Rowe score was 74.6 points and mean Constant score was 70 points. In the disability questionnaire (DASH), the mean value was 22.9 points. The outcome assessment by the patients was positive in 78.8%. The migration of a screw occurred in one patient but he still asymptomatic. No other complication was identified. The Bristow-Latarjet technique is a reliable technique, with few complications and with an excellent rate of recurrence in treatment of chronic shoulder instability as reported in literature; it should be used as primary surgery in some cases and the preoperative ISIS score is an excellent and simple guide to select correctly the surgical technique for each patient.

  15. Osseous Defects Seen in Patients with Anterior Shoulder Instability

    PubMed Central

    Itoi, Eiji

    2015-01-01

    Shoulder surgeons need to be aware of the critical size of the glenoid or humeral osseous defects seen in patients with anterior shoulder instability, since the considerable size of osseous defect is reported to cause postoperative instability. Biomechanical studies have identified the size of the osseous defect which affects stability. Since engagement always occurs between a Hill-Sachs lesion and the glenoid rim, when considering the critical size of the Hill-Sachs lesion, we have to simultaneously consider the size of the glenoid osseous defect. With the newly developed concept of the glenoid track, we are able to evaluate whether a large Hill-Sachs lesion is an "on-track" or "off-track" lesion, and to consider both osseous defects together. In case of an off-track Hill-Sachs lesion, if the glenoid defect is less than 25%, no treatment is required. In this case, the Latarjet procedure or arthroscopic remplissage procedure can be a treatment option. However, if the glenoid defect is more than 25%, treatment such as bone grafting is required. This will convert an off-track lesion to an on-track lesion. After the bone graft or Latarjet procedure, if the Hill-Sachs lesion persists as off-track, then further treatment is necessitated. In case with an on-track Hill-Sachs lesion and a less than 25% glenoid defect, arthroscopic Bankart repair alone is enough. PMID:26640623

  16. MR arthrography evaluation in patients with traumatic anterior shoulder instability.

    PubMed

    Saba, Luca; De Filippo, Massimo

    2017-03-01

    To evaluate retrospectively the diagnostic accuracy of MR arthrography, compared with arthroscopy, in research of the glenoid labrum tear in patients with a first episode of traumatic anterior shoulder instability (TUBS). We retrospectively reviewed the MR arthrography shoulder images of 118 patients with a first episode of TUBS, between June 2014 and May 2016. The overall accuracy of MR arthrography compared with arthroscopy of the glenoid labrum lesions was 94%, sensitivity 93%, and specificity 96%. The sensitivity of MR arthrography for Perthes lesion was 71.4%, and for ALPSA lesion, it was 91%. Slap lesion occurred in 11 out of 77 cases (9.3% of 118 cases). The Hill-Sachs lesion occurred in 48 out of 118 cases (40.7%), while the Hill-Sachs reverse lesion in 4 cases (3.4%). The MR arthrography is accurate in detecting labral injuries. However, other studies are needed to assess the less frequent tear, as Perthes lesion. The presence of the Hill-Sachs lesion could provide useful information about the level of the shoulder instability.

  17. Arthroscopic management of shoulder instabilities: anterior, posterior, and multidirectional.

    PubMed

    Abrams, Jeffrey S; Bradley, James P; Angelo, Richard L; Burks, Robert

    2010-01-01

    may require either soft-tissue or bone grafting to avoid engagement with the anterior edge of the glenoid. These techniques require arthroscopic skill and experience and are currently being performed as open procedures. In the future, it is likely that arthroscopy will be involved in the entire spectrum of treatment for shoulder instability.

  18. Posterior humeral avulsion of the glenohumeral ligament (PHAGL) in anterior shoulder instability

    PubMed Central

    Vedova, Franco Della; Ibáñez, Maximiliano; Alvarez, Victoria; Lépore, Salvador; Sulzle, Vanina Ojeda; Galan, Hernán; Slullitel, Daniel

    2015-01-01

    Introduction: Bankart lesion is the anterior glenohumeral instability most common associated injury. Tears at glenohumeral ligaments can be intra substance or at humeral insertion, this location may be the cause of instability. Posterior humeral avulsion of the glenohumeral ligament (PHAGL) can be an isolated or associated cause of instability and it is usually related to the posterior glenohumeral instability. The aim of this article is to report the clinical assessment and postoperative outcomes of 6 patients with PHAGL with anterior shoulder instability. Materials and Methods: We evaluated six patients with PHAGL due to anterior glenohumeral instability arthroscopically repaired. All 6 patients developed the lesion after a sports-related trauma. Sixty six per cent of patients had associated intra-articular shoulder pathologies. The diagnosis with MRI arthrogram (with gadolinium) was performed preoperatively in 50% of patients. Postoperative evaluation was made with Rowe, ASES and WOSI scores. Results: All patients returned to their previous sports level. One patient had a recurrence. Postoperative scores results are WOSI: 13.13%, Rowe 83.33 and ASES 95.83. Discussion: Humeral avulsions of glenohumeral ligaments represent 25% of capsulolabral injuries. PHAGL injury was initially described as a cause of posterior instability, but according to two other series, our study shows that this lesion may also cause anterior instability. It is critical to have a high index of suspicion and make a correct arthroscopic examination to diagnose this injury, because arthroscopic repair of PHAGL has good postoperative outcomes.

  19. Return to play and recurrent instability after in-season anterior shoulder instability: a prospective multicenter study.

    PubMed

    Dickens, Jonathan F; Owens, Brett D; Cameron, Kenneth L; Kilcoyne, Kelly; Allred, C Dain; Svoboda, Steven J; Sullivan, Robert; Tokish, John M; Peck, Karen Y; Rue, John-Paul

    2014-12-01

    There is no consensus on the optimal treatment of in-season athletes with anterior shoulder instability, and limited data are available to guide return to play. To examine the likelihood of return to sport and the recurrence of instability after an in-season anterior shoulder instability event based on the type of instability (subluxation vs dislocation). Additionally, injury factors and patient-reported outcome scores administered at the time of injury were evaluated to assess the predictability of eventual successful return to sport and time to return to sport during the competitive season. Cohort study (prognosis); Level of evidence, 2. Over 2 academic years, 45 contact intercollegiate athletes were prospectively enrolled in a multicenter observational study to assess return to play after in-season anterior glenohumeral instability. Baseline data collection included shoulder injury characteristics and shoulder-specific patient-reported outcome scores at the time of injury. All athletes underwent an accelerated rehabilitation program without shoulder immobilization and were followed during their competitive season to assess the success of return to play and recurrent instability. Thirty-three of 45 (73%) athletes returned to sport for either all or part of the season after a median 5 days lost from competition (interquartile range, 13). Twelve athletes (27%) successfully completed the season without recurrence. Twenty-one athletes (64%) returned to in-season play and had subsequent recurrent instability including 11 recurrent dislocations and 10 recurrent subluxations. Of the 33 athletes returning to in-season sport after an instability event, 67% (22/33) completed the season. Athletes with a subluxation were 5.3 times more likely (odds ratio [OR], 5.32; 95% CI, 1.00-28.07; P = .049) to return to sport during the same season when compared with those with dislocations. Logistic regression analysis suggests that the Western Ontario Shoulder Instability Index (OR, 1

  20. Evaluation of functional outcomes and complications following modified Latarjet reconstruction in athletes with anterior shoulder instability.

    PubMed

    Colegate-Stone, Toby J; van der Watt, Christelle; de Beer, Joe F

    2015-07-01

    The optimal management of anterior shoulder instability in athletes continues to be a challenge. The present study aimed to evaluate the functional outcomes of athletes with anterior shoulder instability following modified Latarjet reconstruction through assessing the timing of return to sport and complications. Retrospective assessment was performed of athletes (n = 56) who presented with recurrent anterior shoulder instability and were treated with modified congruent arc Latarjet reconstruction over a 1-year period. Rugby union was the predominant sport performed. Pre-operative instability severity index scores were assessed. Postoperative complications were recorded as was the time taken for the athlete to return to sport. Arthroscopic evaluation revealed that 86% of patients had associated bony lesions affecting the glenohumeral joint. The overall complication rate relating to the Latarjet reconstruction was 7%. No episodes of recurrent shoulder instability were noted. Of the patients, 89% returned to competitive sport at the same level as that prior to surgery. The mean time post surgery to returning to full training was 3.2 months. The modified congruent arc Latarjet procedure facilitates early rehabilitation and return to sport. These results support our systematic management protocol of performing modified Latarjet surgery in contact sport athletes with recurrent anterior instability.

  1. Evaluation of functional outcomes and complications following modified Latarjet reconstruction in athletes with anterior shoulder instability

    PubMed Central

    van der Watt, Christelle; de Beer, Joe F

    2015-01-01

    Background The optimal management of anterior shoulder instability in athletes continues to be a challenge. The present study aimed to evaluate the functional outcomes of athletes with anterior shoulder instability following modified Latarjet reconstruction through assessing the timing of return to sport and complications. Methods Retrospective assessment was performed of athletes (n = 56) who presented with recurrent anterior shoulder instability and were treated with modified congruent arc Latarjet reconstruction over a 1-year period. Rugby union was the predominant sport performed. Pre-operative instability severity index scores were assessed. Postoperative complications were recorded as was the time taken for the athlete to return to sport. Results Arthroscopic evaluation revealed that 86% of patients had associated bony lesions affecting the glenohumeral joint. The overall complication rate relating to the Latarjet reconstruction was 7%. No episodes of recurrent shoulder instability were noted. Of the patients, 89% returned to competitive sport at the same level as that prior to surgery. The mean time post surgery to returning to full training was 3.2 months. Conclusions The modified congruent arc Latarjet procedure facilitates early rehabilitation and return to sport. These results support our systematic management protocol of performing modified Latarjet surgery in contact sport athletes with recurrent anterior instability. PMID:27582973

  2. The natural history of the anterior knee instability by stress radiography

    PubMed Central

    de Rezende, Márcia Uchôa; Hernandez, Arnaldo José; Camanho, Gilberto Luis

    2014-01-01

    OBJECTIVE: To analyze the anteroposterior displacement of the knee by means of stress radiography in individuals with unilateral anterior knee instability and relate to time of instability. METHODS: Sixty individuals with intact knees (control group) and 125 patients with unilateral anterior instability (AI group) agreed to participate in the study. Gender, age, weight, height, age at injury, time between injury and testing, and surgical findings are studied. Both groups are submitted to anterior and posterior stress radiographies of both knees. Anterior (ADD) and posterior displacement difference (PDD) were calculated between sides. RESULTS: In the control group ADD and PDD are in average, zero, whereas in the AI group ADD averaged 9.8mm and PDD, 1.92mm. Gender, age, weight, height, age at trauma and presence of menisci's lesions do not intervene in the values of ADD and PDD. Meniscal injuries increase with time. ADD and PDD do not relate with the presence or absence of associated menisci's lesions. The ADD and the PDD are related to each other and increase with time. CONCLUSION: There is a permanent anterior subluxation of the injured knee that is related to the amount of anterior displacement that increases with time. Level of Evidence III, Study Types Case-control study. PMID:25246846

  3. Bony Versus Soft Tissue Reconstruction for Anterior Shoulder Instability

    PubMed Central

    McLaughlin, Richard James; Miniaci, Anthony; Jones, Morgan H.

    2015-01-01

    Background: One complication of anteroinferior glenohumeral shoulder dislocation is a critical bone defect that requires surgical repair to prevent recurrent instability. However, controversy exists regarding the surgical management because both open and arthroscopic surgeries have respective advantages and disadvantages. Moreover, it is difficult to determine the patient’s preferred treatment, as factors that influence treatment choice include recurrence rates, morbidity of the procedures, and patient preferences. Hypothesis: Patients who have a higher probability of recurrent instability after arthroscopic surgery will select open surgery whereas patients with a lower probability of recurrent instability after arthroscopic surgery will favor arthroscopy. Study Design: Economic and decision analysis; Level of evidence, 2. Methods: A decision tree was constructed to model each hypothetical outcome after open or arthroscopic surgery for glenohumeral instability in patients with bone defects. A literature review was performed to determine the probability of occurrence for each node while utility values for each outcome were obtained via patient-administered surveys given to 50 patients without prior history of shoulder injury or dislocation. Fold-back analysis was then performed to show the optimal treatment strategy. Finally, sensitivity analysis established the thresholds at which open treatment becomes the optimal treatment. Results: The ultimate expected value—the objective evaluation of all potential outcomes after choosing either open or arthroscopic surgery—was found to be greater for arthroscopic surgery than for open surgery (87.17 vs 81.64), indicating it to be the preferred treatment. Results of sensitivity analysis indicated that open surgery becomes the preferred treatment when probability of recurrence after arthroscopic treatment is ≥23.8%, although varying the utility, defined as an aggregate patient preference for a particular outcome, has no

  4. The Open Bankart Repair for Traumatic Anterior Shoulder Instability in Teenage Athletes.

    PubMed

    Hatch, Mark D; Hennrikus, William L

    2016-03-03

    Traumatic anterior shoulder instability from recurrent dislocations or subluxations is a debilitating problem for the teenage athlete. The risk of recurrent instability is high in this adolescent population. We performed a retrospective case series analysis of adolescent athletes with recurrent instability treated with open Bankart repair and evaluated functional outcomes as well as redislocation rates. The retrospective study included 21 teenage patients with Bankart lesions and recurrent anterior shoulder instability. There were 19 males (90%) and 2 females (10%) with an average age of 16 years (range, 14 to 18 y). Patients were evaluated based on Rowe and UCLA shoulder scores, return to previous level of sport, external rotation, and recurrence. The average number of anchors used to repair the Bankart lesion was 3 (range, 2 to 5). One patient was lost to follow-up at 6 months after surgery. The remaining 20 patients all had at least 2-year follow-up. The recurrent instability rate was zero. In total, 100% of patients had an excellent result based on an average Rowe score of 96.5 points of 100 points (a score of 90 to 100 is an excellent result). In total, 100% of patients had good/excellent result based on an average UCLA shoulder score of 34 of 35 (a score >27 is a good/excellent result). At final follow-up, 7 patients (34%) had lost an average of 11 degrees of external rotation (range, 5 to 20 degrees) on the injured shoulder with the arm at the side compared with the noninjured shoulder. Contact teenage athletes with recurrent anterior shoulder instability can be treated with open Bankart repair with a low recurrence, excellent functional shoulder outcomes, and return to sport. A small amount of external rotation may be lost with this technique. Care must be taken when considering this method with throwing athletes (ie, quarterback or pitcher). The open Bankart should remain a viable alternative for the adolescent population with recurrent anterior

  5. Anterolateral Drawer Versus Anterior Drawer Test for Ankle Instability: A Biomechanical Model.

    PubMed

    Miller, Adam G; Myers, Stuart H; Parks, Brent G; Guyton, Gregory P

    2016-04-01

    The addition of unconstrained internal rotation to the physical examination could allow for detection of more subtle degrees of ankle instability. We hypothesized that a simulated anterolateral drawer test allowing unconstrained internal rotation of the ankle would provoke greater displacement of the lateral talus in the mortise versus the anterior drawer test. Ten cadaveric lower extremities were tested in a custom apparatus designed to reproduce the anterior drawer test and the anterolateral drawer test, in which the ankle was allowed to internally rotate about the intact deep deltoid ligament while being subluxed anteriorly. Specimens were tested intact and with anterior tibiofibular ligament sectioned. A differential variable reluctance transducer was used to measure lateral talar displacement with anterior forces of 25 and 50 N. No significant differences in talar displacement or ankle rotation were noted in intact specimens between the groups. Among sectioned specimens, significantly more talar displacement (25 N [6.5 ± 1.7 mm vs 3.8 ± 2.4 mm] and 50 N [8.7 ± 0.9 mm vs 4.5 ± 2.5 mm], P < .001) and ankle rotation (25 N [13.9 ± 8.0 degrees vs 0.0 ± 0.0 degrees] and 50 N [23.7 ± 5.8 degrees vs 0.0 ± 0.0 degrees], P < .001) were found in the anterolateral drawer versus anterior drawer group. In an ankle instability model, the anterolateral drawer test provoked almost twice the lateral talus displacement found with the anterior drawer test. Allowing internal rotation of the ankle while testing for ankle instability may allow the examiner to detect more subtle degrees of ankle instability. © The Author(s) 2015.

  6. Anterior Shoulder Instability Is Associated With an Underlying Deficiency of the Bony Glenoid Concavity.

    PubMed

    Moroder, Philipp; Ernstbrunner, Lukas; Pomwenger, Werner; Oberhauser, Florian; Hitzl, Wolfgang; Tauber, Mark; Resch, Herbert; Moroder, Rudi

    2015-07-01

    To determine whether anterior shoulder instability is associated with an inherent deficiency of the bony glenoid concavity, which results in a reduced bony shoulder stability ratio (BSSR). In this case-control study, we searched the institutional database for patients treated for unilateral recurrent anterior shoulder instability. We included 30 consecutive patients with atraumatic instability, 30 consecutive patients with traumatic instability, and 36 matched healthy controls, for a total of 96 shoulders. Computed tomography images of the unaffected shoulders of the instability patients were compared with images of the ipsilateral shoulders of age- and sex-matched healthy controls for differences in glenoid morphology. By use of a mathematical formula based on Pythagorean trigonometric identities, the mean BSSRs of the different groups were calculated and compared. Validation of the formula was accomplished by finite element analysis. The mean BSSR of atraumatic instability patients was 17.9% ± 8.5% and therefore significantly lower than the mean BSSR of 31.1% ± 7.5% of the control group (13.2%; 95% confidence interval [CI], 9.1% to 17.4%; P < .001). The mean BSSR of the traumatic instability group was higher, at 23.9% ± 8.5% (P = .007), but still showed a deficit of 7.2% (95% CI, 2.8% to 11.7%; P = .002) compared with controls. The atraumatic instability group showed a mean reduction of 0.9 mm (95% CI, 0.6 to 1.1 mm; P < .001) in concavity depth and a decrease of 2.9° (95% CI, 0.4° to 5.3°; P = .021) in concavity retroversion, whereas the traumatic instability patients had a reduction of 0.4 mm (95% CI, 0.1 to 0.8 mm; P = .006) in concavity depth. Neither of the instability groups differed significantly from their respective controls in terms of glenoid concavity diameter, head radius, or glenoid vault morphology. Anterior shoulder instability is associated with an inherent flattening of the bony glenoid concavity, which significantly decreases the

  7. Surgical interventions for anterior shoulder instability in rugby players: A systematic review

    PubMed Central

    Sabharwal, Sanjeeve; Patel, Nirav K; Bull, Anthony MJ; Reilly, Peter

    2015-01-01

    AIM: To systematically evaluate the evidence-based literature on surgical treatment interventions for elite rugby players with anterior shoulder instability. METHODS: We conducted a systematic review according to the PRISMA guidelines. A literature search was performed in PubMed, EMBASE and Google Scholar using the following search terms: “rugby” and “shoulder” in combination with “instability” or “dislocation”. All articles published from inception of the included data sources to January 1st 2014 that evaluated surgical treatment of elite rugby players with anterior shoulder instability were examined. RESULTS: Only five studies were found that met the eligibility criteria. A total of 379 shoulders in 376 elite rugby union and league players were included. All the studies were retrospective cohort or case series studies. The mean Coleman Methodological Score for the 5 studies was 47.4 (poor). Owing to heterogeneity amongst the studies, quantitative synthesis was not possible, however a detailed qualitative synthesis is reported. The overall recurrence rate of instability after surgery was 8.7%, and the mean return to competitive play, where reported, was 13 mo. CONCLUSION: Arthroscopic stabilization has been performed successfully in acute anterior instability and there is a preference for open Latarjet-type procedures when instability is associated with osseous defects. PMID:25992318

  8. The contemporary management of anterior knee pain and patellofemoral instability.

    PubMed

    Smith, Toby O; McNamara, Iain; Donell, Simon T

    2013-09-01

    In this review the evidence for the management of patients with patellofemoral disorders is presented confined to anterior knee pain and patellar dislocation (excluding patellofemoral arthritis). Patients present along a spectrum of these two problems and are best managed with both problems considered. The key to managing these patients is by improving muscle function, the patient losing weight (if overweight), and judicious use of analgesics if pain is an important feature. Hypermobility syndrome should always be looked for since this is a prognostic indicator for a poor operative outcome. Operations should be reserved for those with correctable anatomical abnormalities that have failed conservative therapy. The current dominant operation is a medial patellofemoral ligament reconstruction.

  9. Arthroscopic Remplissage for Engaging Hill-Sachs Lesions in Patients With Anterior Shoulder Instability

    PubMed Central

    Camp, Christopher L.; Dahm, Diane L.; Krych, Aaron J.

    2015-01-01

    Anterior shoulder instability is often accompanied by a Hill-Sachs defect on the humeral head that can contribute to recurrent instability if not addressed at the time of surgery. We describe a method of performing arthroscopic remplissage to treat engaging Hill-Sachs lesions in patients with glenohumeral instability. It has the benefits of being an efficient procedure that can be performed with minimal technical difficulty and can be used to augment other stabilization procedures such as labral repair. The indications for this technique include the presence of an engaging Hill-Sachs defect in patients will little or no glenoid bone loss. In appropriately selected patients, arthroscopic remplissage has shown reduced rates of recurrent instability. PMID:26697311

  10. Modified Arthroscopic Latarjet Procedure With Coracoid Exteriorization for Treatment of Anterior Glenohumeral Instability

    PubMed Central

    Ranne, Juha O.; Kainonen, Terho U.; Lehtinen, Janne T.; Heinonen, Olli J.

    2013-01-01

    The Latarjet procedure for treating anterior glenohumeral instability includes transfer of the coracoid and biceps tendon to the anterior glenoid. A modified method for the arthroscopic procedure was developed to facilitate the procedure and minimize the risk of injury to the brachial plexus. The detached coracoid was exteriorized through the anteroinferior portal for drilling and shaping. A Coracoid Drill Guide (Arthrex, Naples, FL) was used to help cut the coracoid to the desired size and make 2 drill holes in the coracoid for fixation to the glenoid. The Coracoid Transfer Instrument (Acierart, Masku, Finland) was designed to facilitate coracoid transfer and serve as a pin guide for fixation. Ten patients with severe anterior glenohumeral instability were treated with this technique. They had only mild to moderate postoperative pain. There were no postoperative infections or recurrent dislocations. The safety of this operation was similar to that of other operations on the coracoid process in the proximity of the brachial plexus. The modified arthroscopic Latarjet procedure may be applied successfully to the treatment of anterior glenohumeral instability, with good patient satisfaction and functional outcome. PMID:24400183

  11. Differences in glenohumeral joint morphology between patients with anterior shoulder instability and healthy, uninjured volunteers.

    PubMed

    Peltz, Cathryn D; Zauel, Roger; Ramo, Nicole; Mehran, Nima; Moutzouros, Vasilios; Bey, Michael J

    2015-07-01

    Traumatic glenohumeral joint (GHJ) dislocations are common, resulting in significant shoulder disability and pain. Previous research indicates that bony morphology is associated with an increased risk of injury in other joints (eg, the knee), but the extent to which bony morphology is associated with traumatic GHJ dislocation is unknown. This study assessed GHJ morphology in patients with anterior GHJ instability and in a control population of healthy volunteers. Bilateral computed tomography scans were used to measure GHJ morphology in both shoulders of 11 patients with instability and 11 control subjects. Specific outcome measures included the glenoid radius of curvature (ROC) in the anterior/posterior (A/P) and superior/inferior (S/I) directions, humeral head ROC, A/P and S/I conformity index, and A/P and S/I stability angle. Compared with the control subjects, the glenoid of the instability the injured shoulder in patients with instability was flatter (ie, higher ROC) in the A/P (P = .001) and S/I (P = .01) directions and this finding was also true for uninjured, contralateral shoulder (A/P: P = .01, S/I: P = .03). No differences in GHJ morphology were detected between the instability patients' injured and contralateral shoulders (P > .07). Similarly, no differences in GHJ morphology were detected between the control subjects' dominant and nondominant shoulders (P > .51). There are significant differences in GHJ morphology between healthy control subjects and both shoulders (injured and uninjured, contralateral) of patients diagnosed with anterior instability after GHJ dislocation. These findings are important clinically because they suggest that glenoid morphology may influence the risk of GHJ dislocation. Copyright © 2015 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Elsevier Inc. All rights reserved.

  12. Partial humeral head resurfacing and Latarjet coracoid transfer for treatment of recurrent anterior glenohumeral instability.

    PubMed

    Moros, Chris; Ahmad, Christopher S

    2009-08-01

    Bone deficiencies of either the humeral head or glenoid fossa may cause recurrent shoulder instability following soft tissue stabilization procedures. The engaging Hill-Sachs lesion, a major risk factor for instability, has been identified in a majority of patients with recurrent anterior instability. Guidance for surgical management of large humeral head deficiency presents few available options, with even fewer clinical data to support any one technique. Anteroinferior glenoid deficiency has also been a well-documented source of recurrent instability. The Latarjet coracoid transfer procedure corrects the glenoid defect by restoring the architecture of the inferior rim. Although coracoid transfer addresses containment on the glenoid, a concomitant large humeral head defect is at risk for engagement on the corrected glenoid. This article describes a case of a 50-year-old man presenting with recurrent right shoulder dislocations status post-open stabilization procedure 10 years prior. Radiologic evaluation demonstrated a large Hill-Sachs lesion with adjacent chondral derangement and a nonunion bony Bankart lesion. The Arthrosurface HemiCap humeral head resurfacing prosthesis (Arthrosurface Inc, Franklin, Massachusetts) was used to address the Hill-Sachs lesion with a Latarjet coracoid transfer procedure. We were unable to identify examples in the literature of the HemiCap used in the correction of a Hill-Sachs lesion for recurrent anterior instability. The HemiCap prosthesis has the benefit of correcting the Hill-Sachs lesion and adjacent chondral defect while preserving uninvolved articular surface. The combination of surgical interventions produced a successful result.

  13. Effectiveness of arthroscopic versus open surgical stabilisation for the management of traumatic anterior glenohumeral instability.

    PubMed

    Ng, Choong; Bialocerkowski, Andrea; Hinman, Rana

    2007-06-01

    Background  Anterior instability is a frequent complication following a traumatic glenohumeral dislocation. Frequently the underlying pathology associated with recurrent instability is a Bankart lesion. Surgical correction of Bankart lesions and other associated pathology is the key to successful treatment. Open surgical glenohumeral stabilisation has been advocated as the gold standard because of consistently low postoperative recurrent instability rates. However, arthroscopic glenohumeral stabilisation could challenge open surgical repair as the gold standard treatment for traumatic anterior glenohumeral instability. Objectives  Primary evidence that compared the effectiveness of arthroscopic versus open surgical glenohumeral stabilisation was systematically collated regarding best-practice management for adults with traumatic anterior glenohumeral instability. Search strategy  A systematic search was performed using 14 databases: MEDLINE, Cumulative Index of Nursing and Allied Health (CINAHL), Allied and Complementary Medicine Database (AMED), ISI Web of Science, Expanded Academic ASAP, Proquest Medical Library, Evidence Based Medicine Reviews, Physiotherapy Evidence Database, TRIP Database, PubMed, ISI Current Contents Connect, Proquest Digital Dissertations, Open Archives Initiative Search Engine, Australian Digital Thesis Program. Studies published between January 1984 and December 2004 were included in this review. No language restrictions were applied. Selection criteria  Eligible studies were those that compared the effectiveness of arthroscopic versus open surgical stabilisation for the management of traumatic anterior glenohumeral instability, which had more than 2 years of follow up and used recurrent instability and a functional shoulder questionnaire as primary outcomes. Studies that used non-anatomical open repair techniques, patient groups that were specifically 40 years or older, or had multidirectional instability or other concomitant

  14. Use of 3-Dimensional Printing for Preoperative Planning in the Treatment of Recurrent Anterior Shoulder Instability

    PubMed Central

    Sheth, Ujash; Theodoropoulos, John; Abouali, Jihad

    2015-01-01

    Recurrent anterior shoulder instability often results from large bony Bankart or Hill-Sachs lesions. Preoperative imaging is essential in guiding our surgical management of patients with these conditions. However, we are often limited to making an attempt to interpret a 3-dimensional (3D) structure using conventional 2-dimensional imaging. In cases in which complex anatomy or bony defects are encountered, this type of imaging is often inadequate. We used 3D printing to produce a solid 3D model of a glenohumeral joint from a young patient with recurrent anterior shoulder instability and complex Bankart and Hill-Sachs lesions. The 3D model from our patient was used in the preoperative planning stages of an arthroscopic Bankart repair and remplissage to determine the depth of the Hill-Sachs lesion and the degree of abduction and external rotation at which the Hill-Sachs lesion engaged. PMID:26759768

  15. Surgical treatment of traumatic anterior shoulder instability in american football players.

    PubMed

    Pagnani, Michael J; Dome, David C

    2002-05-01

    American football players have been reported to be at high risk for postoperative instability after arthroscopic stabilization of anterior shoulder instability. While some authors have recommended open methods of stabilization in athletes who play contact sports, there are few data in the literature showing more favorable results with use of an open technique. We reviewed the results of an open technique of anterior shoulder stabilization in fifty-eight American football players after a minimum of two years of follow-up. Fifty-eight American football players underwent open stabilization with use of a standardized technique for the treatment of recurrent anterior shoulder instability. Forty-seven patients had recurrent dislocations, and the remaining eleven had recurrent subluxations. The average age of the patients was 18.2 years, and the average duration of follow-up was thirty-seven months. Patients were evaluated according to the shoulder scoring system of the American Shoulder and Elbow Surgeons and with use of the shoulder instability score described by Rowe and Zarins. There were no postoperative dislocations. Postoperative subluxation occurred in two patients, neither of whom had had a dislocation prior to the operation. Forward flexion and external rotation returned to within 5 of those of the contralateral shoulder in forty-nine patients. The average score according to the system of the American Shoulder and Elbow Surgeons was 97.0 points, and the average Rowe and Zarins score was 93.6 points. Fifty-five patients had a good or excellent result, and fifty-two of the fifty-eight returned to playing football for at least one year. One patient was forced to stop playing because of recurrent instability. Open stabilization is a predictable method of restoring shoulder stability in American football players while maintaining a range of motion approximating that found after arthroscopic stabilization. Postoperative stability appears to be superior to that

  16. [Chronic anterior and internal instabilities of the knee. Theoretical study. Clinical and radiological diagnosis].

    PubMed

    Lemaire, M; Miremad, C

    1983-01-01

    Antero-medial instability of the knee comprises 96 p. 100 of all knee instabilities. In most instances, the instability is moderate and cannot be analyzed without an adequate understanding of the anatomy and mechanics of the joint. They usually occur after forced movement in medial rotation which ruptures the anterior cruciate ligament and may rupture the postero-medial ligament. Less frequently, they appear after a strain in abduction, flexion and lateral rotation. Some degree of hyper-extension may be added to the primary causal strain. Diagnosis is mainly based on the physical examination which determines the type of surgical procedure that should be made. An anterior draw sign and a click in medial rotation are present when the anterior cruciate ligament is torn. When these signs are very marked, it implies an associated tear of the postero-medial ligament. Standard X-rays and arthrography are most important. Arthroscopy is not of great value and only makes it possible to visualize the meniscus lesions which are important for prognosis. The author describes an original concept of the mechanics of rotation of the knee and the pathogenesis of lesions of the medial capsulo-ligamentous layer.

  17. Recurrent anterior shoulder instability: a review of the Latarjet procedure and its postoperative rehabilitation.

    PubMed

    Fedorka, Catherine J; Mulcahey, Mary K

    2015-02-01

    The shoulder is the most common joint to dislocate in the human body, with the dislocation often occurring in the anterior direction. This injury frequently results in soft tissue injury (eg, labral tear, capsular stretching) or bone injury (eg, glenoid or humeral head bone loss), which commonly leads to persistent deficits of shoulder function and a high risk of subsequent instability episodes in young, active patients. Patients with a significant degree of glenoid bone loss (> 25%) may require surgical intervention using the Latarjet procedure, which is an open bony augmentation of the glenoid. This procedure involves transferring the tip of the coracoid to the anteroinferior glenoid, creating a bony block and musculotendinous sling to prevent instability. Rehabilitation after the procedure is a slow progression over 4 to 6 months to regain range of motion and strength, while protecting the bony augmentation. Recent reports have shown success with the Latarjet procedure, as indicated by patient satisfaction scores and a low rate of recurrent instability.

  18. One step arthroscopically assisted Latarjet and posterior bone-block, for recurrent posterior instability and anterior traumatic dislocation

    PubMed Central

    D’Ambrosi, Riccardo; Perfetti, Carlo; Garavaglia, Guido; Taverna, Ettore

    2015-01-01

    This case presents the challenges of the surgical management for a patient with a history of recurrent posterior shoulder instability and subsequently traumatic anterior dislocation. The patient was already on the waiting list for an arthroscopic posterior stabilization with anchors, when a car accident caused an additional anterior shoulder dislocation. This traumatic anterior dislocation created a bone loss with a glenoid fracture and aggravated the preexisting posterior instability. In order to address both problems, we decided to perform an arthroscopically assisted Latarjet procedure for anterior instability and to stabilize with a bone graft for posterior instability. To our best knowledge, this type of surgical procedure has so far never been reported in the literature. The purpose of this report is to present the surgical technique and to outline the decision making process. PMID:26288539

  19. [Modified arthroscopic Latarjet procedure for the treatment of anterior shoulder instability].

    PubMed

    Wu, G; Jiang, C Y; Lu, Y; Zhu, Y M; Li, F L; Li, X

    2015-04-18

    To present the surgical technique and to evaluate the results of the modified arthroscopic Latarjet procedure. Arthroscopic Latarjet procedure has proven to be a reliable method of treatment for difficult anteroinferior instability of the shoulder joint. However, there is no anterior capsule reattachment and too much subscapularis damage for the classic procedure. From February 2013, we modified the classic procedure with reattachment of anterior joint capsule and muscle-tendon junction splitting of subscapularis. Coracoid graft position was evaluated using CT scanning. From March 2012 to August 2014, 51 modified Latarjet procedures were successfully performed arthroscopically for patients with anterior shoulder instability. According to the CT scanning at the final follow up, the graft was flush with the glenoid in 94.1%, and medially placed in 5.9%. Vertical positioning was perfect in 96.0% (2 to 5 o'clock), too high in 2.0%, and too low in 2.0%. There were no cases of recurrent dislocation or subluxation. The modified arthroscopic Latarjet procedure has shown satisfactory results with good graft positioning. It is a minimal invasive and accurate approach, which combines the advantages of the open procedure.

  20. Analysis of postoperative monitoring of patients undergoing shoulder arthroscopy for anterior instability.

    PubMed

    Almeida, Alexandre; Menegotto, Samuel Millán; Almeida, Nayvaldo Couto de; Agostini, Ana Paula; Almeida, Letícia Agostini de

    2017-01-01

    Analyze the postoperative follow-up of patients undergoing shoulder arthroscopy for treatment of anterior instability and correlate with the prevalence of recurrence. A six-question survey was applied by phone and mail to 65 patients, seeking information on the current result of the surgical procedure. All patients were treated arthroscopically for anterior shoulder instability, with at least 12 months of postoperative time. Patients with associated posterior labial lesions and revision surgeries were not included. At the time of the survey the patients had a median of 56 (IQR: 34.5-110.5) postoperative months. The mean sample age was 24.6 years (maximum = 47, minimum = 12; SD = 7.3). Complaint of pain in the shoulder was observed in 20 patients (30.7%). Dislocation recurrence was observed in 10 patients (15.3%). Forty-four patients (67.6%) considered their shoulder normal, which was more frequent in non-recurrence patients (p < 0.001). Forty-three patients (66.1%) returned to their previous level of sport and there was no difference between recurrence and non-recurrence patients (p = 0.456). It was found that the prevalence of recurrence was 5.6 (95% CI: 1.30-24.46) times higher in individuals who abandoned monitoring before six months postoperatively (p = 0.012). The abandonment of postoperative monitoring in the early stages, when the patients receive orientation for muscle strengthening, proprioceptive education, and dangerous movements to avoid, can increase the rates of recurrent shoulder dislocation in patients treated for anterior instability by arthroscopy.

  1. Relationship Between Glenoid Defects and Hill-Sachs Lesions in Shoulders With Traumatic Anterior Instability.

    PubMed

    Nakagawa, Shigeto; Ozaki, Ritsuro; Take, Yasuhiro; Iuchi, Ryo; Mae, Tatsuo

    2015-11-01

    While the combination of a glenoid defect and a Hill-Sachs lesion in a shoulder with anterior instability has recently been termed a bipolar lesion, their relationship is unclear. To investigate the relationship of the glenoid defect and Hill-Sachs lesion and the factors that influence the occurrence of these lesions as well as the recurrence of instability. Case-control study; Level of evidence, 3. The prevalence and size of both lesions were evaluated retrospectively by computed tomography scanning in 153 shoulders before arthroscopic Bankart repair. First, the relationship of lesion prevalence and size was investigated. Then, factors influencing the occurrence of bipolar lesions were assessed. Finally, the influence of these lesions on recurrence of instability was investigated in 103 shoulders followed for a minimum of 2 years. Bipolar lesions, isolated glenoid defects/isolated Hill-Sachs lesions, and no lesion were detected in 86, 45, and 22 shoulders (56.2%, 29.4%, and 14.4%), respectively. As the glenoid defect became larger, the Hill-Sachs lesion also increased in size. However, the size of these lesions showed a weak correlation, and large Hill-Sachs lesions did not always coexist with large glenoid defects. The prevalence of bipolar lesions was 33.3% in shoulders with primary instability and 61.8% in shoulders with recurrent instability. In relation to the total events of dislocations/subluxations, the prevalence was 44.2% in shoulders with 1 to 5 events, 69.0% in shoulders with 6 to 10 events, and 82.8% in shoulders with ≥11 events. Regarding the type of sport, the prevalence was 58.9% in athletes playing collision sports, 53.3% in athletes playing contact sports, and 29.4% in athletes playing overhead sports. Postoperative recurrence of instability was 0% in shoulders without lesions, 0% with isolated Hill-Sachs lesions, 8.3% with isolated glenoid defects, and 29.4% with bipolar lesions. The presence of a bipolar lesion significantly influenced the

  2. Microperforation prolotherapy: a novel method for successful nonsurgical treatment of atraumatic spontaneous anterior sternoclavicular subluxation, with an illustrative case

    PubMed Central

    Stein, Alvin; McAleer, Scott; Hinz, Marty

    2011-01-01

    Background Surgical repair of an atraumatic spontaneous anterior subluxation of the sternoclavicular joint (herein referred to as the “SCJ”) is often associated with poor outcome expectations. With traditional treatment, successful conservative therapy usually incorporates major lifestyle alterations. This manuscript discusses a novel approach known as “microperforation prolotherapy”. To illustrate the technique, the care of a patient who benefitted from this treatment is reviewed. Purpose To present a novel form of treatment with an illustrative case that demonstrates the potential efficacy of microperforation prolotherapy of the SCJ. Patient and methods A novel approach to treatment of bilateral subluxation of the sternoclavicular joint with microperforation prolotherapy is discussed. The clinical course of a 21-year-old male with bilateral subluxation of the SCJ, which seriously hampered the patient’s athletic and daily living activities, is used as a backdrop to the discussion. Results Following microperforation prolotherapy, the instability of the SCJ was replaced by full stability, complete range of motion, and the opportunity to engage in all of the athletic endeavors previously pursued. There is no scar or other cosmetic defect resulting from the treatment received. Conclusion Anterior sternoclavicular joint subluxation has a poor record of complete recovery with surgical procedures or conservative measures with regard to providing restoration of full lifestyle function. This manuscript documents a novel microperforation prolotherapy treatment that induced healing and restored full stability to the ligament structures responsible for the condition in a completely safe and effective fashion, allowing the patient to resume full lifestyle activities without restriction. The exceptional response to treatment noted here is encouragement for further studies. PMID:24198570

  3. Translation of the glenohumeral joint in patients with anterior instability: awake examination versus examination with the patient under anesthesia.

    PubMed

    Faber, K J; Homa, K; Hawkins, R J

    1999-01-01

    Fifty patients with a clinical diagnosis of traumatic anterior shoulder instability underwent bilateral shoulder translation testing while both awake and under anesthesia. Each patient was examined by 2 surgeons following guidelines developed by the American Shoulder and Elbow Surgeons. A single translation grade was established for anterior, posterior, and inferior directions. A comparison of means was performed with a paired t test. The mean anterior translation grade was significantly higher on the affected side when compared with that of the unaffected side both during awake examination and during examination with the patient under anesthesia (EUA). Ipsilateral comparison revealed significantly greater translation for both affected and unaffected shoulders in anterior, posterior, and inferior directions during EUA than during awake examination. Side-to-side comparison of posterior and inferior translation was similar for both awake examination and EUA. Clinical translation testing was helpful in the diagnosis of anterior shoulder instability. Side-to-side differences were subtle while awake and more apparent during EUA. The usefulness of awake translation testing for traumatic anterior instability was not clearly demonstrated; however, EUA provides helpful information to confirm the direction and degree of instability.

  4. Latarjet Procedure for Anterior Shoulder Instability Due to Tramadol-Induced Seizures: A Multicenter Study.

    PubMed

    Khater, Ahmad Hany; Sobhy, Mohamed H; Said, Hatem G; Kandil, Ahmed; Reda, Walid; Seifeldin, Ahmed Fouad; Moustafa, Ramez; Elassal, Maher A; Kamel, Ezzat M

    2016-04-01

    Seizures, commonly due to epilepsy, are known to cause shoulder instability. Tramadol addiction has recently been found to induce seizures in patients who exceed the recommended dose. Because of the easy accessibility and low cost of tramadol, an increasingly alarming phenomenon of tramadol abuse has been demonstrated in recent years. The purpose of this multicenter study was to investigate shoulder instability resulting from tramadol-induced seizure (TIS) as well as to recommended management for such shoulder instability. The hypothesis was that TIS leads to anterior shoulder dislocations with major bony defects, which favors bony reconstructive procedures as a suitable method of treatment. Case series; Level of evidence, 4. This prospective case series study was conducted on 73 patients (78 shoulders) who presented with anterior shoulder dislocations and a clear history of tramadol abuse. The mean age of the patients was 26.8 years, and the mean number of dislocations was 14. The mean duration of addiction was 17 months, with a mean dose of 752 mg of tramadol hydrochloride per day. Glenoid and humeral bone loss ranged from 15% to 35% and from 15% to 40%, respectively. The mean follow-up period was 28 months. All patients underwent an open Latarjet procedure. Postoperative mean Rowe score and American Shoulder and Elbow Surgeons score at final follow-up (24 months) improved significantly from 20 to 84 and from 44 to 91, respectively (P < .05). The patient satisfaction rate reached 95%, and the mean period of return to work was 12.8 weeks. Five patients (9%) had postoperative seizures due to relapse of the tramadol abuse, but only 3 patients (5%) had redislocations with nonunion or breakage of the graft or hardware. Tramadol addiction has evolved as an important cause of seizures that can result in shoulder dislocation. Anterior shoulder instability with TIS occurs mainly with higher levels of addiction and results in significant humeral and/or glenoid bone defects

  5. Long-term results of the Latarjet procedure for anterior instability of the shoulder.

    PubMed

    Mizuno, Naoko; Denard, Patrick J; Raiss, Patric; Melis, Barbara; Walch, Gilles

    2014-11-01

    The Latarjet procedure is effective in managing anterior glenohumeral instability in the short term, but there is concern for postoperative arthritis. The purpose of this study was to evaluate the long-term functional outcome after the Latarjet procedure and to assess the prevalence of and risk factors for glenohumeral arthritis after this procedure. A retrospective review was conducted of 68 Latarjet procedures at a mean of 20 years postoperatively. The mean age at surgery was 29.4 years. Functional outcome was determined by the Rowe score, subjective shoulder value, and recurrence of instability. Preoperative arthritis and postoperative radiographs were reviewed to evaluate the development or progression of arthritis. The mean Rowe score increased from 37.9 preoperatively to 89.6 at final follow-up (P < .001). The mean subjective shoulder value was 90.9% at final follow-up. The postoperative rate of recurrence was 5.9%. Of the 60 shoulders without arthritis preoperatively, 12 (20%) had developed arthritis at final follow-up. Among the 8 shoulders with preoperative arthritis (all stage 1), 4 (50%) demonstrated progression of arthritis at final follow-up. Overall, postoperative arthritis was stage 1 in 14.7%, stage 2 in 5.9%, and stage 3 in 8.8% of cases; no stage 4 arthritis was observed. Risk factors for postoperative arthritis were older age, high-demand sports activity, and lateral overhang of coracoid bone graft. The Latarjet procedure provides excellent long-term outcomes in the treatment of recurrent anterior glenohumeral instability. Twenty years after the Latarjet procedure, arthritis may develop or progress in 23.5% of cases, but the majority of arthritis is mild. Copyright © 2014 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Elsevier Inc. All rights reserved.

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

    PubMed Central

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

    2015-01-01

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

  7. Results of arthroscopic Bankart repair with Hill-Sachs remplissage for anterior shoulder instability.

    PubMed

    Bonnevialle, Nicolas; Azoulay, Vadim; Faraud, Amélie; Elia, Fanny; Swider, Pascal; Mansat, Pierre

    2017-05-11

    The aim of this study was to evaluate mid-term outcomes of Bankart repair with Hill-Sachs remplissage (BHSR) and to highlight prognostic factors of failure. Thirty-four patients operated on for anterior shoulder instability with BHSR were enrolled in a prospective non-randomised study. Clinical and radiographic evaluation was performed at 1.5, three, six months and yearly thereafter. Outcome measures included Rowe and Walch-Duplay score. At mean follow-up of 35 months (24-63), the Rowe and Walch-Duplay scores reached respectively 92.7 and 88.2 points. The mean deficit in external rotation was 6° in ER1 and 1° in ER2 (p = 0.4, p = 0.9 respectively). Five patients (14.7%) had a recurrence of instability and three others had a persistent anterior apprehension. In the failure group, the Hill-Sachs lesion was deeper (26% vs 19% of the humeral diameter; p = 0.04) and range of motion at 1.5 months postoperatively was greater. Age at surgery, pre-operative instability severity index score (ISIS), hyperlaxity, type and level of sport, amount of glenoid bone loss had no correlation with failure rate. The rate of failure at mid-term follow-up of BHSR was higher than commonly reported. The premature recovery of range of motion seems to be a clinical sign of failure at follow-up. Moreover, in case of deep Hill-Sachs lesion (>20%) an alternative procedure should be considered. Level IV.

  8. Revision open Bankart surgery after arthroscopic repair for traumatic anterior shoulder instability.

    PubMed

    Cho, Nam Su; Yi, Jin Woong; Lee, Bong Gun; Rhee, Yong Girl

    2009-11-01

    Only a few studies have provided homogeneous analysis of open revision surgery after a failed arthroscopic Bankart procedure. Open Bankart revision surgery will be effective in a failed arthroscopic anterior stabilization but inevitably results in a loss of range of motion, especially external rotation. Case series; Level of evidence, 4. Twenty-six shoulders that went through traditional open Bankart repair as revision surgery after a failed arthroscopic Bankart procedure for traumatic anterior shoulder instability were enrolled for this study. The mean patient age at the time of revision surgery was 24 years (range, 16-38 years), and the mean duration of follow-up was 42 months (range, 25-97 months). The preoperative mean range of motion was 173 degrees in forward flexion and 65 degrees in external rotation at the side. After revision surgery, the ranges measured 164 degrees and 55 degrees, respectively (P = .024 and .012, respectively). At the last follow-up, the mean Rowe score was 81 points, with 88.5% of the patients reporting good or excellent results. After revision surgery, redislocation developed in 3 shoulders (11.5%), all of which had an engaging Hill-Sachs lesion and associated hyperlaxity (2+ or greater laxity on the sulcus sign). Open revision Bankart surgery for a failed arthroscopic Bankart repair can provide a satisfactory outcome, including a low recurrence rate and reliable functional return. In open revision Bankart surgery after failed stabilization for traumatic anterior shoulder instability, the surgeon should keep in mind the possibility of a postoperative loss of range of motion and a thorough examination for not only a Bankart lesion but also other associated lesions, including a bone defect or hyperlaxity, to lower the risk of redislocation.

  9. Shoulder problems in high level swimmers--impingement, anterior instability, muscular imbalance?

    PubMed

    Rupp, S; Berninger, K; Hopf, T

    1995-11-01

    The objective was to study prevalence and underlying pathology of "swimmer's shoulder". Twenty-two competitive swimmers of national "D-Kader" (elite development swimmers) were evaluated by means of questionnaire, clinical examination and isokinetic testing of external rotation and internal rotation. At the examination current interfering pain necessitating a cessation or reduction of practice was found in 5 (23%) athletes. At isokinetic testing 8 (36%) athletes complained of shoulder pain. Any history of pain was seen in 14 (64%) swimmers. A positive impingement sign was noted in 11 (50%) athletes. Apprehension sign which is indicative of anterior instability was found in 11 (50%) swimmers. Clinical equivalents of dysfunction of scapulothoracic muscles such as scapular winging (5 athletes) and shoulder protraction (12 athletes) were noted. For comparison of results of isokinetic testing a control group of non-swimmers was selected matching the group of swimmers exactly in terms of age, sex and dominant side. External rotation/internal rotation ratio of peak torque and total work at 60 deg/sec and 180 deg/sec was significantly lower in swimmers than in controls. The ratio was independent of sex, dominant side, history of pain and pain at examination. During internal rotation competitive swimmers produced significantly higher peak torques and total work than controls. There was no significant difference in external rotation. In conclusion there are several different abnormalities of function contributing to the pathology of "swimmer's shoulder":--Laxity of anterior-inferior capsuloligamentous structures with atruamatic anterior instability due to repetitive overload.--Impingement with rotator cuff tendinitis.--Muscular imbalance of the rotator cuff muscles and scapulothoracic dysfunction.

  10. Anterior approach for operative fixation of coronoid fractures in complex elbow instability.

    PubMed

    Reichel, Lee M; Milam, Graham S; Reitman, Charles A

    2012-06-01

    The coronoid process has been shown to play a critical role in ulnohumeral stability. Coronoid process fractures can occur in isolation or as part of a complex injury pattern. The most common complex pattern, known as the "terrible triad," includes a radial head fracture and elbow dislocation along with the coronoid fracture. Failure to address these fractures and ligamentous injuries can result in recurrent instability and progression to painful arthrosis. Both medial and lateral approaches to the coronoid have been popularized in recent literature, but there is no universally accepted approach. Common fixation techniques include suture lasso, suture anchors, lag screws, and plating all of which have various drawbacks. We describe a direct anterior approach to address coronoid process fractures made in addition to a lateral approach to address radial head and lateral collateral ligament injuries. Coronoid fractures addressed through the anterior approach were stabilized with anterior to posterior screw fixation combined with buttress plating, which allowed anatomic reduction and stable internal fixation at short-term follow-up.

  11. Minimally invasive modified latarjet procedure in patients with traumatic anterior shoulder instability.

    PubMed

    Ebrahimzadeh, Mohammad Hossein; Moradi, Ali; Zarei, Ahmad Reza

    2015-03-01

    Despite recent advances in arthroscopic soft tissue repair and reconstruction for shoulder instability, Latarjet procedure is continuously a method of choice for many cases of unstable shoulders. To evaluate the clinical results of minimally invasive modified Latarjet technique in recurrent, traumatic anterior shoulder instability associated with obvious Hill-Sachs and Bankart lesions. Between 2007 and 2013, 36 consequent patients with traumatic anterior shoulder instability who underwent modified Latarjet operation were enrolled in this prospective study. The MRI studies revealed labrum detachment and Hill-Sachs lesion in all shoulders. For all patients, demographic and injury data were obtained and Constant Shoulder score, Rowe score, and UCLA scores were completed by related surgeon. Stability of the shoulder was assessed with the Jobe's relocation test preoperatively. The patients were followed up at two weeks, one month, three months, and six months from the date of the surgery and evaluated for probable complications. Above mentioned assessments were completed again at the time of the final follow-up. The average age of the enrolled patients was 24.6 (ranging from 18 to 33 years) and 35 patients out of the total of 36 patients were males. Motor-vehicle accidents were the major cause of the injuries (52%) with the average interval between the injury and operation of 3.1 ± 1.2 years (Ranging from 1 to 5 years). The average number of incidents of dislocations between the injury date and the surgery was 7.2 ± 2.1 (Ranging from 4 to 20). The average follow-up period was 37 months (Ranging from 12 to 65 months). All patients had Jobe's relocation test (Apprehension sign) pre-operatively and negative Jobe's relocation test post-operation. Significant improvements in functional scores were demonstrated postoperatively compared to preoperational assessment in all cases. Final follow up radiographs showed union of all the grafts and patients reported no incidents of

  12. Minimally Invasive Modified Latarjet Procedure in Patients With Traumatic Anterior Shoulder Instability

    PubMed Central

    Ebrahimzadeh, Mohammad Hossein; Moradi, Ali; Zarei, Ahmad Reza

    2015-01-01

    Background: Despite recent advances in arthroscopic soft tissue repair and reconstruction for shoulder instability, Latarjet procedure is continuously a method of choice for many cases of unstable shoulders. Objectives: To evaluate the clinical results of minimally invasive modified Latarjet technique in recurrent, traumatic anterior shoulder instability associated with obvious Hill-Sachs and Bankart lesions. Patients and Methods: Between 2007 and 2013, 36 consequent patients with traumatic anterior shoulder instability who underwent modified Latarjet operation were enrolled in this prospective study. The MRI studies revealed labrum detachment and Hill-Sachs lesion in all shoulders. For all patients, demographic and injury data were obtained and Constant Shoulder score, Rowe score, and UCLA scores were completed by related surgeon. Stability of the shoulder was assessed with the Jobe’s relocation test preoperatively. The patients were followed up at two weeks, one month, three months, and six months from the date of the surgery and evaluated for probable complications. Above mentioned assessments were completed again at the time of the final follow-up. Results: The average age of the enrolled patients was 24.6 (ranging from 18 to 33 years) and 35 patients out of the total of 36 patients were males. Motor-vehicle accidents were the major cause of the injuries (52%) with the average interval between the injury and operation of 3.1 ± 1.2 years (Ranging from 1 to 5 years). The average number of incidents of dislocations between the injury date and the surgery was 7.2 ± 2.1 (Ranging from 4 to 20). The average follow-up period was 37 months (Ranging from 12 to 65 months). All patients had Jobe’s relocation test (Apprehension sign) pre-operatively and negative Jobe’s relocation test post-operation. Significant improvements in functional scores were demonstrated postoperatively compared to preoperational assessment in all cases. Final follow up radiographs showed

  13. [Treatment of chronic anterior shoulder instability using a coracoid bone block (Latarjet procedure): 74 cases].

    PubMed

    Collin, P; Rochcongar, P; Thomazeau, H

    2007-04-01

    Results of the Latarjet procedure for chronic anterior shoulder instability using a coracoid block are known in terms of recurrence, but not in terms of apprehension. We studied a prospective consecutive series of shoulders treated with the Latarjet method in order to determine whether patients forget their shoulder or whether they are still bothered, particularly during sports activities. The series included 74 patients with chronic anterior shoulder instability treated with a coracoid block according to the Latarjet procedure. Sixty-nine were available for review and 66 had complete radiographic explorations (93.2%). The Duplay score was used to classify sports activities. Mean age was 26.5 years; 90% of the patients practiced sports. The surgical procedure was performed by the same operator for 78% of patients. The Duplay score and the Constant score were determined and standard x-rays (four views) were obtained. Statistical analysis was performed with the chi-square test. Multivariate analysis was then applied to the subpopulation presenting persistent apprehension. Follow-up was at least 24 months, average follow-up 50 months. Four patients presented secondary dislocation and two subluxation; 85% of patients were satisfied, 6% were hesitant and 9% were dissatisfied. The Duplay score was: excellent (18.8%), good (49.9%), fair (20.2%) and poor (10.1%). External elbow rotation (RE1) was limited by 17.69 degrees compared with the other side. Eighty-seven percent of patients resumed their sports activity five months postoperatively on average; 34% presented persistent apprehension. This subpopulation was examined separately. Multivariate analysis demonstrated two significantly independent factors of persistent apprehension: recovery of RE1 at 30 days postop, and total recovery of R1 at last follow-up. The radiographies demonstrated degenerative lesions in 10.6% of patients. The satisfaction rate of 85% and the 9% failure rate are similar to earlier reports. Our

  14. Assessment of anterolateral rotatory instability in the anterior cruciate ligament-deficient knee using an open magnetic resonance imaging system.

    PubMed

    Okazaki, Ken; Miura, Hiromasa; Matsuda, Shuich; Yasunaga, Takefumi; Nakashima, Hideaki; Konishi, Kozo; Iwamoto, Yukihide; Hashizume, Makoto

    2007-07-01

    In the clinical evaluation of the anterior cruciate ligament-deficient knee, anterolateral rotatory instability is assessed by manual tests such as the pivot-shift test, which is subjective and not quantitative. The anterolateral rotatory instability in an anterior cruciate ligament-deficient knee can be quantified by our newly developed method using open magnetic resonance imaging. Controlled laboratory study. Eighteen subjects with anterior cruciate ligament-deficient knees and 18 with normal knees were recruited. We administered the Slocum anterolateral rotatory instability test in the open magnetic resonance imaging scanner and scanned the sagittal view of the knee. The anterior displacements of the tibia at the medial and lateral compartments were measured. Furthermore, we examined 14 anterior cruciate ligament-deficient knees twice to assess intraobserver and interobserver reproducibility and evaluated the difference and interclass correlation coefficient of 2 measures. In the anterior cruciate ligament-deficient knee, displacement was 14.4 +/- 5.5 mm at the lateral compartment and 1.6 +/- 2.3 mm at the medial compartment; in the normal knee, displacement was 0.7 +/- 1.9 mm and -1.1 +/- 1.2 mm, respectively. The difference and interclass correlation coefficient between 2 repeated measures at the lateral compartment were 1.0 +/- 0.7 mm and .98 for intraobserver reproducibility and 1.1 +/- 0.7 mm and .91 for interobserver reproducibility. This method is useful to assess the anterolateral rotatory instability of the anterior cruciate ligament-deficient knee. This method can be used in the clinical assessment of anterior cruciate ligament stability, such as comparing studies of graft positions or 2-bundle anatomic reconstruction and the conventional 1-bundle technique.

  15. Anterior cruciate ligament augmentation for rotational instability following primary reconstruction with an accelerated physical therapy protocol.

    PubMed

    Carey, Timothy; Oliver, David; Pniewski, Josh; Mueller, Terry; Bojescul, John

    2013-01-01

    The purpose of the present study is to present the results of anterior cruciate ligament (ACL) augmentation for patients having rotational instability despite an intact vertical graft in lieu of conventional revision ACL reconstruction. ACL augmentation surgery with a horizontal graft was performed to augment a healed vertical graft on five patients and an accelerated rehabilitation protocol was instituted. Functional outcomes were assessed by the Lower Extremity Functional Scale (LEFS) and the Modified Cincinnati Rating System (MCRS). All patients completed physical therapy within 5 months and were able to return to full military duty without limitation. LEFS and MCRS were significantly improved. ACL augmentation with a horizontal graft provides an excellent alternative to ACL revision reconstruction for patients with an intact vertical graft, allowing an earlier return to duty for military service members.

  16. Anterior-inferior shoulder instability: treatment based on the Thal method.

    PubMed

    Russo, R; Giudice, G; Ciccarelli, M; Vernaglia Lombardi, L; Cautiero, F

    2005-01-01

    Purpose of this study is to analyze the results of a consecutive series of 139 patients affected with anterior-inferior shoulder instability and treated by arthroscopic capsuloplasty using the Thal method with absorbable and non-absorbable Mitek knotless anchors. Much attention was paid to the preoperative and intraoperative selection of patients, excluding from the arthroscopic procedure those with bony Bankart lesions measuring more than 25%, with an inverted-pear glenoid, with engaged Hill-Sachs lesions and patients with HAGL lesions. Pre- and postoperative clinical evaluation was carried out using the Rowe scale. Scores rose from 45-55 to 96 postoperatively. Intra-articular mobilization of the anchors did not occur and peri-metallic lysis was not manifested. Areas of bone resorption were observed in 7 cases (7/38, 18.4%) with the presence of peri-insertional geodes with biological anchors, but this had no effect on the clinical results.

  17. Recurrent Anterior Shoulder Instability With Combined Bone Loss: Treatment and Results With the Modified Latarjet Procedure.

    PubMed

    Yang, Justin S; Mazzocca, Augustus D; Cote, Mark P; Edgar, Cory M; Arciero, Robert A

    2016-04-01

    Recurrent anterior glenohumeral dislocation in the setting of an engaging Hill-Sachs lesion is high. The Latarjet procedure has been well described for restoring glenohumeral stability in patients with >25% glenoid bone loss. However, the treatment for patients with combined humeral head and mild (<25%) glenoid bone loss remains unclear. This study reports on the outcomes of the modified Latarjet for patients with combined humeral and glenoid defects and compares the results for patients with ≤25% glenoid bone loss versus patients with >25% glenoid bone loss. The hypothesis was that the 2 groups would have equivalent subjective outcomes and recurrence rates. Cohort Study; Level of evidence, 3. Modified Latarjet was performed in 40 patients with recurrent anterior shoulder instability, engaging Hill-Sachs by examination confirmed with arthroscopy, and ≤25% anterior glenoid bone loss (group A). A second group of 12 patients were identified to have >25% glenoid bone loss with an engaging Hill-Sachs lesion (group B). The mean follow-up time was 3.5 years. All patients were assessed for their risk of recurrence using the Instability Severity Index score and Beighton score and had preoperative 3-dimensional imaging to assess humeral and glenoid bone loss. Single Assessment Numeric Evaluation (SANE), Western Ontario Shoulder Instability Index (WOSI), recurrence rate, radiographs, range of motion, and dynamometer strength were used to assess outcomes. A multivariate analysis was performed. Glenoid bone loss averaged 15% in group A compared with 34% in group B. Both groups had comparable WOSI scores (356 vs 475; P = .311). In multivariate analysis, the number of previous surgeries and Beighton score were directly correlated with WOSI score in Latarjet patients. The SANE score was better in group A (86 vs 77; P = .02). Group B experienced more loss of external rotation (9.2° vs 15.8°; P = .0001) and weaker thumbs-down abduction and external rotation strength (P < .032

  18. Long term results of arthroscopic Bankart repair for traumatic anterior shoulder instability.

    PubMed

    Ee, Gerard W W; Mohamed, Sedeek; Tan, Andrew H C

    2011-06-14

    The arthroscopic method offers a less invasive technique of Bankart repair for traumatic anterior shoulder instability. We would like to report the 2 year clinical outcomes of bio-absorbable suture anchors used in traumatic anterior dislocations of the shoulder. Data from 79 shoulders in 74 patients were collected over 4 years (2004-2008). Each patient was followed-up over a period of 2 years. The patients underwent arthroscopic Bankart repair using bio-absorbable suture anchors for their shoulder instability. These surgeries were performed at a single institution by a single surgeon over the time period. The patients were assessed with two different outcome measurement tools. The University of California at Los Angeles (UCLA) shoulder rating scale and the Simple Shoulder Test (SST) score. The scores were calculated before surgery and at the 2-year follow-up. The recurrence rates, range of motion as well post-operative function and return to sporting activities were evaluated. SST results from the 12 domains showed a significant improvement from a mean of 6.1 ± 3.1 to 11.1 ± 1.8 taken at the 2-year follow-up (p < 0.0001). Data from the UCLA scale showed a Pre and Post Operative Mean of 20.2 ± 5.0 and 32.4 ± 4.6 respectively (p < 0.0001). 34 had excellent post-operative scores, 35 had good scores, 1 had fair score and 3 had poor scores. 75% of the patients returned to sports while 7.6% developed a recurrence of shoulder dislocation or subluxation. Arthroscopic Bankart repair with the use of suture anchors is a reliable treatment method, with good clinical outcomes, excellent post-operative shoulder motion and low recurrence rates.

  19. Long term results of arthroscopic bankart repair for traumatic anterior shoulder instability

    PubMed Central

    2011-01-01

    Background The arthroscopic method offers a less invasive technique of Bankart repair for traumatic anterior shoulder instability. We would like to report the 2 year clinical outcomes of bio-absorbable suture anchors used in traumatic anterior dislocations of the shoulder. Methods Data from 79 shoulders in 74 patients were collected over 4 years (2004 - 2008). Each patient was followed-up over a period of 2 years. The patients underwent arthroscopic Bankart repair using bio-absorbable suture anchors for their shoulder instability. These surgeries were performed at a single institution by a single surgeon over the time period. The patients were assessed with two different outcome measurement tools. The University of California at Los Angeles (UCLA) shoulder rating scale and the Simple Shoulder Test (SST) score. The scores were calculated before surgery and at the 2-year follow-up. The recurrence rates, range of motion as well post-operative function and return to sporting activities were evaluated. Results SST results from the 12 domains showed a significant improvement from a mean of 6.1 ± 3.1 to 11.1 ± 1.8 taken at the 2-year follow-up (p < 0.0001). Data from the UCLA scale showed a Pre and Post Operative Mean of 20.2 ± 5.0 and 32.4 ± 4.6 respectively (p < 0.0001). 34 had excellent post-operative scores, 35 had good scores, 1 had fair score and 3 had poor scores. 75% of the patients returned to sports while 7.6% developed a recurrence of shoulder dislocation or subluxation. Conclusion Arthroscopic Bankart repair with the use of suture anchors is a reliable treatment method, with good clinical outcomes, excellent post-operative shoulder motion and low recurrence rates. PMID:21672187

  20. Mean Glenoid Defect Size and Location Associated With Anterior Shoulder Instability

    PubMed Central

    Gottschalk, Lionel J.; Bois, Aaron J.; Shelby, Marcus A.; Miniaci, Anthony; Jones, Morgan H.

    2017-01-01

    Background: There is a strong correlation between glenoid defect size and recurrent anterior shoulder instability. A better understanding of glenoid defects could lead to improved treatments and outcomes. Purpose: To (1) determine the rate of reporting numeric measurements for glenoid defect size, (2) determine the consistency of glenoid defect size and location reported within the literature, (3) define the typical size and location of glenoid defects, and (4) determine whether a correlation exists between defect size and treatment outcome. Study Design: Systematic review; Level of evidence, 4. Methods: PubMed, Ovid, and Cochrane databases were searched for clinical studies measuring glenoid defect size or location. We excluded studies with defect size requirements or pathology other than anterior instability and studies that included patients with known prior surgery. Our search produced 83 studies; 38 studies provided numeric measurements for glenoid defect size and 2 for defect location. Results: From 1981 to 2000, a total of 5.6% (1 of 18) of the studies reported numeric measurements for glenoid defect size; from 2001 to 2014, the rate of reporting glenoid defects increased to 58.7% (37 of 63). Fourteen studies (n = 1363 shoulders) reported defect size ranges for percentage loss of glenoid width, and 9 studies (n = 570 shoulders) reported defect size ranges for percentage loss of glenoid surface area. According to 2 studies, the mean glenoid defect orientation was pointing toward the 3:01 and 3:20 positions on the glenoid clock face. Conclusion: Since 2001, the rate of reporting numeric measurements for glenoid defect size was only 58.7%. Among studies reporting the percentage loss of glenoid width, 23.6% of shoulders had a defect between 10% and 25%, and among studies reporting the percentage loss of glenoid surface area, 44.7% of shoulders had a defect between 5% and 20%. There is significant variability in the way glenoid bone loss is measured, calculated

  1. Current concepts in the management of recurrent anterior gleno-humeral joint instability with bone loss

    PubMed Central

    Ramhamadany, Eamon; Modi, Chetan S

    2016-01-01

    The management of recurrent anterior gleno-humeral joint instability is challenging in the presence of bone loss. It is often seen in young athletic patients and dislocations related to epileptic seizures and may involve glenoid bone deficiency, humeral bone deficiency or combined bipolar lesions. It is critical to accurately identify and assess the amount and position of bone loss in order to select the most appropriate treatment and reduce the risk of recurrent instability after surgery. The current literature suggests that coracoid and iliac crest bone block transfers are reliable for treating glenoid defects. The treatment of humeral defects is more controversial, however, although good early results have been reported after arthroscopic Remplissage for small defects. Larger humeral defects may require complex reconstruction or partial resurfacing. There is currently very limited evidence to support treatment strategies when dealing with bipolar lesions. The aim of this review is to summarise the current evidence regarding the best imaging modalities and treatment strategies in managing this complex problem relating particularly to contact athletes and dislocations related to epileptic seizures. PMID:27335809

  2. Arthroscopic treatment of anterior shoulder instability associated with a HAGL lesion-a case series.

    PubMed

    Flury, Matthias; Rickenbacher, Dominik; Audigé, Laurent

    2016-12-01

    Restoration of shoulder stability after humeral avulsion of glenohumeral ligament (HAGL) lesions can be achieved with arthroscopy, yet limited evidence exists on its benefit. We evaluated objective and subjective outcomes after arthroscopic refixation of a HAGL lesion. Between 2009 and 2012, 8 patients were treated arthroscopically for anterior shoulder instability associated with a HAGL lesion and invited for a follow-up examination. Radiographic assessment of joint centering and osteoarthritis, clinical assessment including Constant and Rowe scores, and complications as well as functional outcomes using the Western Ontario Shoulder Instability Index, Subjective Shoulder Value, and Simple Shoulder Test were documented. Six patients were postoperatively examined at a median time of 29 months (range, 12-38). Four patients had up to 6 previous luxation events. Two patients had a concomitant labral lesion, and another 2 had an associated rotator cuff tear. Positive preoperative apprehension and relocation test results for 5 patients were negative at follow-up. No neurologic lesion was noted both before and after surgery. Shoulder motion did not improve significantly; lower internal and external rotation relative to the contralateral shoulder was reported. The Rowe score improved significantly from baseline (median score change, 65 points; P = .027), with 2 and 4 patients rating "good" and "excellent" at follow-up, respectively. Final median Constant score, Western Ontario Shoulder Instability Index, Subjective Shoulder Value, and Simple Shoulder Test scores were 77.3 points, 91.0 points, 90%, and 87.5 points, respectively. Arthroscopic stabilization of a HAGL lesion is a safe, feasible, and reproducible technique. In our patient cohort, good shoulder stability could be achieved with high patient satisfaction. Copyright © 2016 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Elsevier Inc. All rights reserved.

  3. Traumatic anterior instability of the pediatric shoulder: a comparison of arthroscopic and open bankart repairs.

    PubMed

    Shymon, Stephen J; Roocroft, Joanna; Edmonds, Eric W

    2015-01-01

    Arthroscopic and open Bankart repairs have proven efficacy in adults with recurrent anterior shoulder instability. Although studies have included children in their analysis, none have previously compared functional outcomes or redislocation rates between these 2 methodologies for anteroinferior glenoid labrum repair in this young population. We hypothesize that open and arthroscopic Bankart repair in children will have similar functional outcomes and redislocation rates, but differing results from adults treated in a similar manner. A retrospective chart review was performed on all Bankart repairs performed between 2006 and 2010 at a tertiary care children's hospital. A shift in treatment modalities occurred in 2008 creating 2 cohorts, open and arthroscopic. Brachial plexus injury, congenital soft-tissue disorder, or incomplete charts were excluded. Demographics, age at surgery, follow-up length, and sport were recorded. Telephone interviews were then performed obtaining the most current QuickDASH (Disability Arm, Shoulder, or Hand), WOSI (Western Ontario Shoulder Instability Index), SF-12 (Short Form 12), SANE (Single Assessment Numeric Evaluation), and verbal pain scores; as well as, inquiring about recurrent dislocation and further surgery. Ninety-nine children (16.9±1.5 y) were included (28 open, 71 arthroscopic). There were no differences in preoperative demographics. Fifty-one patients completed the questionnaires (11 open, 40 arthroscopic). No significant differences in the outcomes scores were seen between the 2 groups. Of the 99 patients, 21 (21%) had redislocation or secondary surgery; there was no significant difference in failure rate between groups (4 open, 17 arthroscopic). A plotted survival curve demonstrated that the adolescent shoulder undergoing Bankart repair for recurrent traumatic anterior instability has a 2-year survival of 86% and a 5-year survival of only 49%, regardless of technique. In adolescents, there is no significant difference in

  4. Effect of Arthroscopic Stabilization on In Vivo Glenohumeral Joint Motion and Clinical Outcomes in Patients With Anterior Instability.

    PubMed

    Peltz, Cathryn D; Baumer, Timothy G; Mende, Veronica; Ramo, Nicole; Mehran, Nima; Moutzouros, Vasilios; Bey, Michael J

    2015-11-01

    Glenohumeral joint (GHJ) dislocations are common, and the resulting shoulder instability is often treated with arthroscopic stabilization. These procedures result in favorable clinical outcomes, but abnormal GHJ motion may persist, which may place patients at risk for developing osteoarthritis. However, the effects of shoulder instability and arthroscopic stabilization on GHJ motion are not well understood. GHJ motion is significantly influenced by anterior instability and arthroscopic stabilization, but postsurgical measures of GHJ motion are not different from those of control subjects. Controlled laboratory study. In vivo GHJ motion was measured by applying a computed tomographic model-based tracking technique to biplane radiographic images acquired during an apprehension test in healthy control subjects (n = 11) and anterior instability patients (n = 11). Patients were tested before surgery and at 6 months after surgery. Control subjects were tested once. Shoulder strength, active range of motion (ROM), and the Western Ontario Shoulder Instability (WOSI) index were also measured. Before surgery, the humerus of the instability patients during the apprehension test was located significantly more anteriorly on the glenoid (7.9% of glenoid width; 2.1 mm) compared with that of the controls (P = .03), but arthroscopic stabilization moved this joint contact location posteriorly on the glenoid (4.7% of glenoid width; 1.1 mm; P = .03). After surgery, GHJ excursion during the apprehension test was significantly lower (14.7% of glenoid width; 3.6 mm) compared with presurgical values (19.4% of glenoid width; 4.7 mm; P = .01) and with that of the controls (22.4% of glenoid width; 5.7 mm; P = .01). The external and internal rotation strength of patients was significantly lower than that of the controls before surgery (P < .05), but differences in strength did not persist after surgery (P > .17). External rotation ROM in patients was significantly lower than that in control

  5. Postoperative Recurrence of Instability Due to New Anterior Glenoid Rim Fractures After Arthroscopic Bankart Repair.

    PubMed

    Nakagawa, Shigeto; Hirose, Takehito; Tachibana, Yuta; Iuchi, Ryo; Mae, Tatsuo

    2017-10-01

    Computed tomography (CT) sometimes reveals a new fracture of the anterior glenoid rim in patients with postoperative recurrence of instability after arthroscopic Bankart repair using suture anchors, but there have been few previous reports about such fractures. The placement of a large number of suture anchors during arthroscopic Bankart repair might be associated with a new glenoid rim fracture. Cohort study; Level of evidence, 3. Screw-in metal suture anchors were used until June 2011 and suture-based soft anchors from July 2011. A follow-up of at least 2 years was conducted for 128 shoulders treated using metal anchors (metal anchor group) and 129 shoulders treated using soft anchors (soft anchor group). The frequency and features of new glenoid rim fractures were investigated, and the influence of the number of suture anchors and other factors on fractures was also assessed. There were 19 shoulders (14.8%) with postoperative recurrence in the metal anchor group and 23 shoulders (17.8%) in the soft anchor group. Among 37 shoulders evaluated by CT at recurrence, a new glenoid rim fracture was detected in 13 shoulders (35.1%; 5 shoulders in the metal anchor group and 8 shoulders in the soft anchor group). A fracture at the anchor insertion site was recognized in 4 shoulders from the metal anchor group and 6 shoulders from the soft anchor group, although linear fractures connecting several anchor holes were only seen in the soft anchor group. While new glenoid fractures occurred regardless of the number of suture anchors used, new fractures were significantly more frequent in teenagers at surgery and in junior high school or high school athletes. Such fractures did not only occur in contact athletes but were also found in overhead athletes. Postoperative recurrence of instability associated with a new glenoid rim fracture along the suture anchor insertion site was frequent after arthroscopic Bankart repair. These fractures might be related to placing multiple soft

  6. Arthroscopic Bankart repair and subscapularis augmentation: an alternative technique treating anterior shoulder instability with bone loss.

    PubMed

    Maiotti, Marco; Russo, Raffaele; Zanini, Antonio; Schröter, Steffen; Massoni, Carlo; Bianchedi, Diana

    2016-06-01

    This study presents the preliminary results of a new arthroscopic technique consisting of the association of 2 procedures, capsulolabral repair and subscapularis augmentation tenodesis, in the treatment of traumatic anterior shoulder instability with both glenoid bone loss and a Hill-Sachs lesion. Eighty-nine patients engaged in sports were enrolled in this retrospective case-series study with 2 to 5 years' follow-up. All patients underwent a computed tomography scan to assess the percentage of glenoid bone loss by the Pico method. A prior stabilization procedure had failed in 20 patients, who were then segregated into a different group. Visual analog scale (VAS), Rowe, and American Shoulder and Elbow Surgeons (ASES) scores were used to assess the results. Only 3 of 89 patients had a post-traumatic redislocation. The mean length of follow-up was 31.5 months (range, 25-60 months). The VAS, Rowe, and ASES scores showed significant improvements: The VAS score decreased from a mean of 3.1 to 0.5 (P = .0157), the Rowe score increased from 58.9 to 94.1 (P = .0215), and the ASES score increased from 68.5 to 95.5 (P = .0197). The mean deficit of external rotation was 6° with the arm at the side of the trunk, and the mean deficit was 3° with the arm in 90° of abduction. The described procedure is a reproducible and effective technique used to restore joint stability in patients engaged in sports who have incurred anterior recurrent shoulder dislocation associated with glenoid bone loss (<25%) and a Hill-Sachs lesion. Copyright © 2016 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Elsevier Inc. All rights reserved.

  7. Treatment of Bankart lesions in traumatic anterior instability of the shoulder: a randomized controlled trial comparing arthroscopy and open techniques.

    PubMed

    Archetti Netto, Nicola; Tamaoki, Marcel Jun Sugawara; Lenza, Mario; dos Santos, João Baptista Gomes; Matsumoto, Marcelo Hide; Faloppa, Flavio; Belloti, João Carlos

    2012-07-01

    The objective of this study was to compare the functional assessments of arthroscopy and open repair for treating Bankart lesion in traumatic anterior shoulder instability. Fifty adult patients, aged less than 40 years, with traumatic anterior shoulder instability and the presence of an isolated Bankart lesion confirmed by diagnostic arthroscopy were included in the study. They were randomly assigned to receive open or arthroscopic treatment of an isolated Bankart lesion. In all cases of both groups, the lesion was repaired with metallic suture anchors. The primary outcomes included the Disabilities of the Arm, Shoulder and Hand (DASH) questionnaire. After a mean follow-up period of 37.5 months, 42 patients were evaluated. On the DASH scale, there was a statistically significant difference favorable to the patients treated with the arthroscopic technique, but without clinical relevance. There was no difference in the assessments by University of California, Los Angeles and Rowe scales. There was no statistically significant difference regarding complications and failures, as well as range of motion, for the 2 techniques. On the basis of this study, the open and arthroscopic techniques were effective in the treatment of traumatic anterior shoulder instability. The arthroscopic technique showed a lower index of functional limitation of the upper limb, as assessed by the DASH questionnaire; this, however, was not clinically relevant. Copyright © 2012 Arthroscopy Association of North America. Published by Elsevier Inc. All rights reserved.

  8. Anterior subluxation of the lateral tibial plateau. A new clinical test and the morbidity of this type of knee instability.

    PubMed

    Martens, M A; Mulier, J C

    1981-01-01

    A new clinical test is presented for the diagnosis of anterolateral knee instability. The advantages of the test are obviation of apprehension- and muscle spasm avoiding false negative results and also the recognition by the patient of his sensation of "collapsing at the knee". This allows for differentiation between "giving away" due to a torn meniscus alone and concomitant anterolateral knee instability. It implies important consequences for prognosis and treatment of the knee problem of the athlete. Underlying pathology consists of a torn anterior cruciate ligament and primary or secondary stretching of the soft tissues at the lateral and posterolateral capsule. These lesions and a positive test for anterolateral knee instability does not inevitably result in a disability for sports activity. The dynamic muscular control protects the knee in many instances from collapsing at cross over cutting.

  9. Bristow-Latarjet Technique: Still a Very Successful Surgery for Anterior Glenohumeral Instability - A Forty Year One Clinic Experience

    PubMed Central

    Ruci, Vilson; Duni, Artid; Cake, Alfred; Ruci, Dorina; Ruci, Julian

    2015-01-01

    AIM: To evaluate the functional outcomes of the Bristow-Latarjet procedure in patients with recurrent anterior glenohumeral instability. PATIENTS AND METHODS: Personal clinical records of 42 patients with 45 operated shoulders were reviewed retrospectively. Patient age at time of first dislocation, injury mechanism, and number of recurring dislocations before surgery were recorded. The overall function and stability of the shoulder was evaluated. RESULTS: Thirty five (78%) of the scapulohumeral humeral instabilities were caused by trauma. The mean number of recurring dislocations was 9 (95% confidence interval [CI], 0–18); one patient had had 17 recurrences. Mean follow-up 46 months (95% CI, 16-88). No dislocation happened postoperatively. Four patients have fibrous union (9%). Only two had clinical sign of pain and discomfort. One of them was reoperated for screw removal with very good post-operative result. The overall functional outcome was good, with a mean Rowe score of 88 points (95% CI, 78–100). Scores of 27 (64%) of the patients were excellent, 9 (22%) were good, 4 (9.5%) were fair, and 2 (4.5%) were poor. CONCLUSION: The Bristow-Latarjet procedure is a very good surgical treatment for recurrent anterior-inferior instability of the glenohumeral joint. It must not be used for multidirectional instability or psychogenic habitual dislocations. PMID:27275242

  10. Bristow-Latarjet Technique: Still a Very Successful Surgery for Anterior Glenohumeral Instability - A Forty Year One Clinic Experience.

    PubMed

    Ruci, Vilson; Duni, Artid; Cake, Alfred; Ruci, Dorina; Ruci, Julian

    2015-06-15

    To evaluate the functional outcomes of the Bristow-Latarjet procedure in patients with recurrent anterior glenohumeral instability. Personal clinical records of 42 patients with 45 operated shoulders were reviewed retrospectively. Patient age at time of first dislocation, injury mechanism, and number of recurring dislocations before surgery were recorded. The overall function and stability of the shoulder was evaluated. Thirty five (78%) of the scapulohumeral humeral instabilities were caused by trauma. The mean number of recurring dislocations was 9 (95% confidence interval [CI], 0-18); one patient had had 17 recurrences. Mean follow-up 46 months (95% CI, 16-88). No dislocation happened postoperatively. Four patients have fibrous union (9%). Only two had clinical sign of pain and discomfort. One of them was reoperated for screw removal with very good post-operative result. The overall functional outcome was good, with a mean Rowe score of 88 points (95% CI, 78-100). Scores of 27 (64%) of the patients were excellent, 9 (22%) were good, 4 (9.5%) were fair, and 2 (4.5%) were poor. The Bristow-Latarjet procedure is a very good surgical treatment for recurrent anterior-inferior instability of the glenohumeral joint. It must not be used for multidirectional instability or psychogenic habitual dislocations.

  11. Arthroscopic Latarjet and Capsular Shift (ALCS) procedure: a new "freehand" technique for anterior shoulder instability associated with significant bone defects.

    PubMed

    Bhatia, Deepak N

    2015-03-01

    Anterior shoulder instability associated with significant bone loss has been described as "bony-instability," and this condition is usually treated with an anterior glenoid bone grafting procedure (Latarjet procedure). The Latarjet procedure involves transfer of the horizontal limb of the coracoid process along with the conjoint tendon to the anterior glenoid rim, and is traditionally performed as an open surgical procedure. Recently, an arthroscopic technique for the Latarjet procedure has been described; the technique necessitates the use of specialized instrumentation and involves excision of the entire anterior capsule to facilitate coracoid fixation. We describe a new "freehand" arthroscopic technique for the Latarjet procedure, and, in addition, a simultaneous capsular shift to further optimize mid and end range stability. This technique eliminates the use of additional instrumentation and can be done using routine arthroscopic instruments. Preliminary experience with this technique suggests that the arthroscopic Latarjet and capsular shift is a technically demanding procedure. Glenohumeral capsule can be preserved, and this should be attempted wherever possible to optimize stability. Additional specialized instrumentation would probably reduce surgical time; however, the procedure can be performed with routine instruments.

  12. Value of stress ultrasound for the diagnosis of chronic ankle instability compared to manual anterior drawer test, stress radiography, magnetic resonance imaging, and arthroscopy.

    PubMed

    Cho, Jae Ho; Lee, Doo Hyung; Song, Hyung Keun; Bang, Joon Young; Lee, Kyung Tai; Park, Young Uk

    2016-04-01

    Clinicians frequently diagnose chronic ankle instability using the manual anterior drawer test and stress radiography. However, both examinations can yield incorrect results and do not reveal the extent of ankle instability. Stress ultrasound has been reported to be a new diagnostic tool for the diagnosis of chronic ankle instability. The purpose of this study was to assess the diagnostic value of stress ultrasound for chronic ankle instability compared to the manual anterior drawer test, stress radiography, magnetic resonance imaging (MRI), and arthroscopy. Twenty-eight consecutive patients who underwent ankle arthroscopy and subsequent modified Broström repair for treatment of chronic ankle instability were included. The arthroscopic findings were used as the reference standard. A standardized physical examination (manual anterior drawer test), stress radiography, MRI, and stress ultrasound were performed to assess the anterior talofibular ligament (ATFL) prior to operation. Ultrasound images were taken in the resting position and the maximal anterior drawer position. Grade 3 lateral instability was verified arthroscopically in all 28 cases with a clinical diagnosis (100%). Twenty-two cases showed grade III instability on the manual anterior drawer test (78.6%). Twenty-four cases displayed anterior translation exceeding 5 mm on stress radiography (86%), and talar tilt angle exceeded 15° in three cases (11 %). Nineteen cases displayed a partial chronic tear (change in thickness or signal intensity), and nine cases displayed complete tear on MRI (100%). Lax and wavy ATFL was evident on stress ultrasound in all cases (100 %). The mean value of the ATFL length was 2.8 ± 0.3 cm for the stressed condition and 2.1 ± 0.2 cm for the resting condition (p < 0.001). Stress ultrasound may be useful for the diagnosis of chronic ankle instability in addition to the manual anterior drawer test and stress radiography. III.

  13. Diagnosis and treatment of anteroinferior capsular redundancy associated with anterior shoulder instability using an open Latarjet procedure and capsulorrhaphy.

    PubMed

    Ropars, Mickaël; Cretual, Armel; Kaila, Rajiv; Bonan, Isabelle; Hervé, Anthony; Thomazeau, Hervé

    2016-12-01

    There is a paucity of data detailing management of anterior capsular redundancy (ACR) when using the Latarjet procedure for unidirectional instability. This study aimed to describe the surgical management and to assess the clinical profile of patients presenting with anterior capsular redundancy [ACR(+)] with anterior shoulder instability. Seventy-seven patients who had a Latarjet procedure were followed for a 55-month period. Per-operative ACR was assessed during surgery. ACR was considered present if the inferior capsular flap of a Neer T-shaft capsulorrhaphy was able to cover the superior capsular flap with the arm in the neutral position. Patients with ACR(+) received an additional Neer capsulorrhaphy, while patients with ACR(-) did not. This per-operative finding was correlated with demographics, clinical, radiological pre-operative data and surgical outcome. Patients presenting with a per-operative ACR(+) were significantly associated with a sulcus sign (P < 0.001), a Beighton score >4 (P < 0.01), a low-energy instability history (P < 0.05), a predominant history of subluxations (P < 0.05), fewer Hill-Sachs lesion (P < 0.05) and a female gender (P < 0.05), but not significantly with external rotation >85°. Open standard Latarjet procedures with Neer capsulorrhaphy in ACR(+) patients showed excellent or good results and stability rate of 95 %. All patients except four who presented with a new dislocation after surgery were satisfied with their outcome. Thirteen patients (16 %) had a persistent apprehension sign at the last follow-up. ACR(+) and ACR(-) groups did not show significant difference in the mean values of Rowe, Walch-Duplay and Constant-Murley scores. ACR correlated with a sulcus sign, Beighton score and instability history. In anterior shoulder instability associated with ACR, the Latarjet procedure with a Neer capsulorrhaphy appears a satisfactory treatment alternative to arthroscopic or open capsular shift. It decreased

  14. Short-Term Outcomes of Glenoid Bone Block Augmentation for Complex Anterior Shoulder Instability in a High-Risk Population.

    PubMed

    Waterman, Brian R; Chandler, Philip J; Teague, Edward; Provencher, Matthew T; Tokish, John M; Pallis, Mark P

    2016-09-01

    To describe the short-term clinical outcomes of glenoid bone block augmentation in a high-demand population, as well as to describe its clinical success and complications at greater than 2 years' follow-up in an at-risk military population. All patients undergoing anterior capsulorrhaphy with coracoid process transfer or anterior bone block augmentation (Current Procedural Terminology code 23662 or 23460) for shoulder instability between 2006 and 2012 were isolated from the Military Health System Management Analysis and Reporting Tool. Demographic and occupational parameters were identified, and multiple surgical factors and clinical outcomes were extracted from the medical record and US Defense Manpower Data Center. A total of 64 service members (65 shoulders) underwent anterior bone block procedures, including coracoid transfer (n = 59, 90.8%), distal tibial allograft (n = 3, 4.6%), and autologous or allograft iliac crest bone graft (n = 3, 4.6%). This group was predominately comprised of men (n = 59), and the mean age was 25.9 years (range, 19 to 45 years). A total of 19 perioperative complications, including 8 neurologic injuries, 6 infections, and 4 hardware failures, occurred in 16 patients (25%). At a mean 2.4-year follow-up, 21 patients (32.8%) reported persistent shoulder pain and 15 patients (23.4%) disclosed subjective apprehension or recurrent instability. Secondary surgical procedures were performed in 12 patients (18.8%), including 4 revisions (6.3%). Ultimately, 20 patients (31.3%) underwent a medical discharge for persistent shoulder disability. Univariate analysis showed that the presence of a perioperative complication (P = .049) and tobacco use (P = .038) were associated with increased risk of subsequent surgical failure. Anterior glenoid bone block procedures for shoulder instability with concomitant bone loss enable a return to high-demand physical function. The short-term complication profile (25%), recurrence rate (23%), and

  15. Arthroscopic Remplissage and Open Latarjet Procedure for the Treatment of Anterior Glenohumeral Instability With Severe Bipolar Bone Loss.

    PubMed

    Katthagen, J Christoph; Anavian, Jack; Tahal, Dimitri S; Millett, Peter J

    2016-10-01

    Bipolar bone loss in patients with anterior glenohumeral instability is challenging to treat. The goal of the treatment is to restore stability by ensuring that the humeral head remains within the glenoid vault. This can be achieved either with the combination of an arthroscopic Bankart procedure and remplissage (glenoid bone loss <25%), or with a Latarjet procedure (glenoid bone loss >25%). In cases with more severe bipolar bone loss of both the glenoid and the humeral head, the conventional approach has been to lengthen the articular arc of the glenoid and to ignore the Hill-Sachs lesion. However, it has recently been shown that this can still lead to an "off-track" situation with persistent shoulder instability from engagement of the Hill-Sachs on the anterior glenoid. In these cases, the combination of a Hill-Sachs remplissage and the Latarjet procedure can be effective in preventing persistent instability. In this technical note, the surgical technique of an arthroscopic Hill-Sachs remplissage in combination with an open Latarjet procedure is presented.

  16. Arthroscopic double-pulley remplissage technique for engaging Hill-Sachs lesions in anterior shoulder instability repairs.

    PubMed

    Koo, Samuel S; Burkhart, Stephen S; Ochoa, Eloy

    2009-11-01

    We present a modified arthroscopic technique used to treat anterior shoulder instability associated with mild glenoid bone loss and a large Hill-Sachs lesion. The procedure aims to convert a bony intra-articular defect into an extra-articular defect by insetting the infraspinatus into the Hill-Sachs lesion. The arthroscopic procedure is performed with the patient in the lateral decubitus position, and the same portals used for anterior instability repair are used for this technique. The sequence of steps involves placing and passing the glenoid anchors and sutures and then waiting to tie the anterior sutures until after the humeral suture anchors have been placed. The subacromial bursa is cleared; then 2 transtendon suture anchors are placed in the Hill-Sachs lesion. Next, the previously placed Bankart repair sutures are tied, and finally, the remplissage sutures are tied in the subacromial space over the infraspinatus by use of the transtendon double-pulley technique. This technique uses the eyelets of the 2 suture anchors as pulleys and creates a double-mattress suture.

  17. Anterior shoulder instability with engaging Hill-Sachs defects: a comparison of arthroscopic Bankart repair with and without posterior capsulodesis.

    PubMed

    Cho, Nam Su; Yoo, Jae Hyun; Juh, Hyung Suk; Rhee, Yong Girl

    2016-12-01

    The purpose of this study was to compare the clinical results of isolated arthroscopic Bankart repair and those of arthroscopic Bankart repair with posterior capsulodesis for anterior shoulder instability with engaging Hill-Sachs lesions. Thirty-five shoulders that underwent isolated arthroscopic Bankart repair (Bankart group) and 37 shoulders that underwent arthroscopic Bankart repair with posterior capsulodesis (remplissage group) for anterior shoulder instability with engaging Hill-Sachs lesions were evaluated retrospectively. The mean age at the time of the surgery was 26.1 ± 7.0 years in the Bankart group and 24.8 ± 9.0 years in the remplissage group. At the final follow-up, the Rowe and UCLA scores significantly improved in both the Bankart and remplissage groups (P < 0.001, in both groups). The post-operative mean deficit in external rotation at the side was 3° ± 10° in the Bankart group and 8° ± 23° in the remplissage group (P = n.s. and P = 0.044, respectively). There was no decrease in muscle strength in either group. The recurrence rate was 25.7 % in the Bankart group and 5.4 % in the remplissage group (P = 0.022). Arthroscopic Bankart repair with posterior capsulodesis demonstrated good clinical outcomes with a low recurrence rate in the treatment for anterior shoulder instability with an engaging Hill-Sachs lesion. Although a limitation in external rotation was observed, there was no significant limitation of any other motion and no decrease in muscle strength after the remplissage procedure. Posterior capsulodesis alone for remplissage should be considered as a surgical technique that can replace the conventional method. Case-control study, Level III.

  18. Management of sternoclavicular dislocation in young children: considerations about diagnosis and treatment of four cases.

    PubMed

    Gil-Albarova, J; Rebollo-González, S; Gómez-Palacio, V E; Herrera, A

    2013-08-01

    The records of 4 children of under 14 years of age treated at our institution for traumatic sternoclavicular dislocation (SCJ) were reviewed. Closed reduction in posterior SCJ after computed tomography (CT) was successful as immediate procedure. For anterior SCJ instability, open reduction and SCJ reconstruction obtained satisfactory results. Conservative treatment of SCJ subluxation for asymptomatic children was sufficient. Radiographs in "serendipity view" were useful for confirming reduction and stability in children. No postoperative CT was needed for this purpose. Closed reduction in posterior SCJ dislocation and surgical treatment in anterior SCJ dislocation in young children can provide stability and a satisfactory return to a normal function, but with some limitation when intense or competitive shoulder motion is required during sport. Young children and parents should be aware about this possibility. Conservative treatment of SCJ subluxation for asymptomatic children is useful. Reflection is required regarding the correct imaging examination after treatment to check stable reduction in a SCJ injury.

  19. Arthroscopic Bankart repair and capsular shift for recurrent anterior shoulder instability: functional outcomes and identification of risk factors for recurrence.

    PubMed

    Ahmed, Issaq; Ashton, Fiona; Robinson, Christopher Michael

    2012-07-18

    Arthroscopic Bankart repair and capsular shift is a well-established technique for the treatment of anterior shoulder instability. The purpose of this study was to evaluate the outcomes following arthroscopic Bankart repair and capsular shift and to identify risk factors that are predictive of recurrence of glenohumeral instability. We performed a retrospective review of a prospectively collected database consisting of 302 patients who had undergone arthroscopic Bankart repair and capsular shift for the treatment of recurrent anterior glenohumeral instability. The prevalence of patient and injury-related risk factors for recurrence was assessed. Cox proportional hazards models were used to estimate the predicted probability of recurrence within two years. The chief outcome measures were the risk of recurrence and the two-year functional outcomes assessed with the Western Ontario shoulder instability index (WOSI) and disabilities of the arm, shoulder and hand (DASH) scores. The rate of recurrent glenohumeral instability after arthroscopic Bankart repair and capsular shift was 13.2%. The median time to recurrence was twelve months, and this complication developed within one year in 55% of these patients. The risk of recurrence was independently predicted by the patient's age at surgery, the severity of glenoid bone loss, and the presence of an engaging Hill-Sachs lesion (all p < 0.001). These variables were incorporated into a model to provide an estimate of the risk of recurrence after surgery. Varying the cutoff level for the predicted probability of recurrence in the model from 50% to lower values increased the sensitivity of the model to detect recurrences but decreased the positive predictive value of the model to correctly predict failed repairs. There was a significant improvement in the mean WOSI and DASH scores at two years postoperatively (both p < 0.001), but the mean scores in the group with recurrence were significantly lower than those in the group

  20. Results of Arthroscopic Bankart Repair for Anterior-Inferior Shoulder Instability at 13-Year Follow-up.

    PubMed

    Aboalata, Mohamed; Plath, Johannes E; Seppel, Gernot; Juretzko, Julia; Vogt, Stephan; Imhoff, Andreas B

    2017-03-01

    Anterior-inferior shoulder instability is a common injury in young patients, particularly those practicing overhead-throwing sports. Long-term results after open procedures are well studied and evaluated. However, the long-term results after arthroscopic repair and risk factors of recurrence require further assessment. Arthroscopic Bankart repair results are comparable with those of open repair as described in the literature. Case series; Level of evidence, 4. A total of 180 shoulders with anterior-inferior shoulder instability were stabilized arthroscopically, met the inclusion criteria and the patients were able to be contacted at a minimum of 10-year follow-up. Of these patients, 143 agreed to participate in the study. Assessment was performed clinically in 104 patients using the American Shoulder and Elbow Surgeons score, Constant score, American Academy of Orthopaedic Surgeons score, Rowe score, and the Dawson 12-item questionnaire. The Samilson-Prieto score was used to assess degenerative arthropathy in radiographs available for 100 shoulders. Additionally, 15 patients participated through a specific questionnaire and 24 patients through a telephone survey. The overall redislocation rate was 18.18%. Redislocation rates for the different types of fixation devices were as follows: FASTak/Bio-FASTak, 15.1% (17/112); SureTac, 26.3% (5/19); and Panalok, 33.3% (4/12). Concomitant superior labral anterior-posterior repair had no effect on clinical outcome. Redislocation rate was significantly affected by the patient's age and duration of postoperative rehabilitation. Redislocation rate tended to be higher if there had been more than 1 dislocation preoperatively ( P = .098). Severe dislocation arthropathy was observed in 12% of patients, and degenerative changes were significantly correlated with the number of preoperative dislocations, patient age, and number of anchors. The patient satisfaction rate was 92.3%, and return to the preinjury sport level was possible in

  1. A review of ultrasonographic methods for the assessment of the anterior cruciate ligament in patients with knee instability - diagnostics using a posterior approach.

    PubMed

    Poboży, Tomasz; Kielar, Maciej

    2016-09-01

    The purpose of the study was to improve the ultrasonographic assessment of the anterior cruciate ligament by an inclusion of a dynamic element. The proposed functional modification aims to restore normal posterior cruciate ligament tension, which is associated with a visible change in the ligament shape. This method reduces the risk of an error resulting from subjectively assessing the shape of the posterior cruciate ligament. It should be also emphasized that the method combined with other ultrasound anterior cruciate ligament assessment techniques helps increase diagnostic accuracy. Ultrasonography is used as an adjunctive technique in the diagnosis of anterior cruciate ligament injury. The paper presents a sonographic technique for the assessment of suspected anterior cruciate ligament insufficiency supplemented by the use of a dynamic examination. This technique can be recommended as an additional procedure in routine ultrasound diagnostics of anterior cruciate ligament injuries. Supplementing routine ultrasonography with the dynamic assessment of posterior cruciate ligament shape changes in patients with suspected anterior cruciate ligament injury reduces the risk of subjective errors and increases diagnostic accuracy. This is important especially in cases of minor anterior knee instability and bilateral anterior knee instability. An assessment of changes in posterior cruciate ligament using a dynamic ultrasound examination effectively complements routine sonographic diagnostic techniques for anterior cruciate ligament insufficiency.

  2. A review of ultrasonographic methods for the assessment of the anterior cruciate ligament in patients with knee instability – diagnostics using a posterior approach

    PubMed Central

    Kielar, Maciej

    2016-01-01

    Aim The purpose of the study was to improve the ultrasonographic assessment of the anterior cruciate ligament by an inclusion of a dynamic element. The proposed functional modification aims to restore normal posterior cruciate ligament tension, which is associated with a visible change in the ligament shape. This method reduces the risk of an error resulting from subjectively assessing the shape of the posterior cruciate ligament. It should be also emphasized that the method combined with other ultrasound anterior cruciate ligament assessment techniques helps increase diagnostic accuracy. Methods Ultrasonography is used as an adjunctive technique in the diagnosis of anterior cruciate ligament injury. The paper presents a sonographic technique for the assessment of suspected anterior cruciate ligament insufficiency supplemented by the use of a dynamic examination. This technique can be recommended as an additional procedure in routine ultrasound diagnostics of anterior cruciate ligament injuries. Results Supplementing routine ultrasonography with the dynamic assessment of posterior cruciate ligament shape changes in patients with suspected anterior cruciate ligament injury reduces the risk of subjective errors and increases diagnostic accuracy. This is important especially in cases of minor anterior knee instability and bilateral anterior knee instability. Conclusions An assessment of changes in posterior cruciate ligament using a dynamic ultrasound examination effectively complements routine sonographic diagnostic techniques for anterior cruciate ligament insufficiency. PMID:27679732

  3. Successful Return to Sport After Arthroscopic Shoulder Stabilization Versus Nonoperative Management in Contact Athletes With Anterior Shoulder Instability: A Prospective Multicenter Study.

    PubMed

    Dickens, Jonathan F; Rue, John-Paul; Cameron, Kenneth L; Tokish, John M; Peck, Karen Y; Allred, C Dain; Svoboda, Steven J; Sullivan, Robert; Kilcoyne, Kelly G; Owens, Brett D

    2017-09-01

    The debate continues regarding the optimal treatment of intercollegiate contact athletes with in-season anterior shoulder instability. To examine return to sport and recurrent instability in the season after the index in-season anterior instability event. Cohort study; Level of evidence, 2. Forty-five contact intercollegiate athletes treated nonoperatively or with arthroscopic stabilization were prospectively followed in a multicenter observational study to evaluate return to play (RTP) and recurrent instability in the season after an initial in-season anterior glenohumeral instability event. Baseline data collection included sport played, previous instability events, direction of instability, type of instability (subluxation or dislocation), and treatment method (nonoperative management or arthroscopic stabilization). All nonoperatively treated athletes underwent a standardized accelerated rehabilitation program without shoulder immobilization. Surgical stabilization was performed arthroscopically in all cases, and successful RTP was evaluated during the next competitive season after complete rehabilitation. Thirty-nine of 45 intercollegiate contact athletes had remaining National Collegiate Athletic Association eligibility and were followed through the subsequent competitive season after the index instability event. Of the 10 athletes electing nonoperative treatment, 4 (40%) successfully returned to play without recurrence during the subsequent season. Of the 29 athletes treated surgically, 26 (90%) were able to successfully return to play without recurrence the following season (recurrence: n = 1; inadequate function: n = 2). Athletes who underwent surgical reconstruction before the next season were 5.8 times (95% CI, 1.77-18.97; P = .004) more likely to complete the subsequent season without recurrent instability. Of the 29 athletes electing surgical stabilization, there was no difference (risk ratio, 0.95; 95% CI, 0.10-9.24; P > .99) in RTP between the 9

  4. The arthroscopic latarjet procedure for anterior shoulder instability: 5-year minimum follow-up.

    PubMed

    Dumont, Guillaume D; Fogerty, Simon; Rosso, Claudio; Lafosse, Laurent

    2014-11-01

    The arthroscopic Latarjet procedure combines the benefits of arthroscopic surgery with the low rate of recurrent instability associated with the Latarjet procedure. Only short-term outcomes after arthroscopic Latarjet procedure have been reported. To evaluate the rate of recurrent instability and patient outcomes a minimum of 5 years after stabilization performed with the arthroscopic Latarjet procedure. Case series; Level of evidence, 4. Patients who underwent the arthroscopic Latarjet procedure before June 2008 completed a questionnaire to determine whether they had experienced a dislocation, subluxation, or further surgery. The patients also completed the Western Ontario Shoulder Instability Index (WOSI). A total of 62 of 87 patients (64/89 shoulders) were contacted for follow-up. Mean follow-up time was 76.4 months (range, 61.2-100.7 months). No patients had reported a dislocation since their surgery. One patient reported having subluxations since the surgery. Thus, 1 patient (1.59%) had recurrent instability after the procedure. The mean ± standard deviation aggregate WOSI score was 90.6% ± 9.4%. Mean WOSI domain scores were as follows: Physical Symptoms, 90.1% ± 8.7%; Sports/Recreation/Work, 90.3% ± 12.9%; Lifestyle, 93.7% ± 9.8%; and Emotions, 88.7% ± 17.3%. The rate of recurrent instability after arthroscopic Latarjet procedure is low in this series of patients with a minimum 5-year follow-up. Patient outcomes as measured by the WOSI are good. © 2014 The Author(s).

  5. The anterior shear and distraction tests for craniocervical instability. An evaluation using magnetic resonance imaging.

    PubMed

    Osmotherly, Peter G; Rivett, Darren A; Rowe, Lindsay J

    2012-10-01

    Screening for integrity of the ligaments of the craniocervical complex has been suggested prior to the application of manual techniques to the upper cervical spine. However, most tests proposed lack validation limiting their usefulness clinically. This study examined the effect of the anterior shear test for the transverse ligament and the distraction test for the tectorial membrane in normal volunteers. MRI was performed in supine in neutral and end-range stress test positions in 16 individuals using proton density-weighted sequences and a standard head coil in a 3-T system. Measurements were made with respect to a strictly standardised protocol. The anterior shear test was assessed using changes in atlantodental interval and distance from the anterior arch of the atlas to the posterior aspect of the odontoid process. Distraction testing for the tectorial membrane was assessed by changes in basion-dental interval and by direct measurement of the tectorial membrane. Differences were compared using Wilcoxon Sign Rank tests or paired t-test depending upon each variables assessment of normality. Anterior shear testing resulted in a 0.41 mm mean increase in atlantodental interval (p = 0.03) and 0.35 mm mean increase in axial plane distance (p = 0.05). Distraction testing for the tectorial membrane resulted in a 0.64 mm increase in basion-dental interval (p < 0.01) and a 1.11 mm increase in direct ligament length measurement (p = 0.02). Reliability of measurements ranged from moderate to substantial. These results indicate that these tests produce a consistent direct effect on the transverse ligament and the tectorial membrane which is consistent with their theorised mechanism for clinical use. Copyright © 2012 Elsevier Ltd. All rights reserved.

  6. The anterior talo-fibular ligament reconstruction in surgical treatment of chronic lateral ankle instability.

    PubMed

    Trc, Tomás; Handl, Milan; Havlas, Vojtech

    2010-10-01

    Chronic lateral ankle instability causes significant problems in physical activity and accelerates development of osteoarthritic changes. The results of treatment for chronic ankle instability are often meets controversial. A surgical reconstruction of ATFL as described in this paper was performed during the period 1997-2005 on 47 patients (26 male, 21 female), with a mean age of 29.3 years. The average follow-up period was 46.2 months. All patients had clinical examination, X-ray and MRI. The mean values of the Good score improved from an average 3.32 prior to surgery to 1.19 one year after the operation. Paired t-tests showed improvements of great significance (p < 10(-28)). The Good score prior to surgery ranged from 2-4, whereas the scores one year after surgery were either 1 or 2, with a score of 1 being recorded in 38 cases (81%). In the postoperative follow-up, MRI showed a newly-formed ligament structure in all cases. The authors describe their own technique for a reconstruction of lateral ankle instability using remnants of the former ATFL. The scar tissue seems to be sufficient to form a new duplicated structure providing good stability. MRI proved to be a sensitive and specific method for identifying the extent of talo-fibular ligament injury.

  7. Arthroscopic Repair of Inferior Labrum From Anterior to Posterior Lesions Associated With Multidirectional Instability of the Shoulder

    PubMed Central

    Burt, David M.

    2014-01-01

    Multidirectional instability (MDI) of the shoulder may arise spontaneously; however, recent evidence suggests that traumatic events may play a role in this syndrome. Variable degrees of injury around the circumference of the glenoid have been reported, ranging from Bankart and Kim lesions to 270° of injury and even 360° of injury. Hyperabduction injury may cause inferior subluxation of the shoulder and result in traumatic isolated injury to the inferior labrum from anterior to posterior. This particular lesion spans approximately 180° of the inferior hemisphere and may lead to symptomatic MDI. In contrast to open or arthroscopic plication procedures for atraumatic MDI without labral injury, the goal in these cases is anatomic arthroscopic repair of the inferior labrum tear without the need for capsular plication, volume reduction, or rotator interval closure. PMID:25685683

  8. Latarjet procedure using subscapularis split approach offers better rotational endurance than partial tenotomy for anterior shoulder instability.

    PubMed

    Ersen, Ali; Birisik, Fevzi; Ozben, Hakan; Atalar, Ata Can; Sahinkaya, Turker; Seyahi, Aksel; Demirhan, Mehmet

    2017-03-03

    Latarjet, which is a coracoid bone block procedure, is an effective treatment for anterior shoulder instability with glenoid bone loss. During this reconstructive procedure the subscapularis may be tenotomized or be split to expose the glenoid neck. The aim of this study was to assess the effect of subscapularis management on functional outcomes and internal and external rotation durability and strength. Hypothesis is that the subscapularis split approach will result in better functional results and superior internal rotation strength and endurance. The study included 48 patients [median age 30 (range 16-69); 42 males, 6 females], who underwent a modified Latarjet procedure for anterior shoulder instability. There were 20 patients in the subscapularis tenotomy group and 28 patients in the subscapularis split group. The groups were compared isokinetically using a computerized dynamometer for internal and external rotation durability and strength. At the latest follow-up, the patients were evaluated with the American Shoulder and Elbow Surgeons (ASES) and ROWE scores for functional outcomes. At a median follow-up period of 25 (range 12-73) months after the Latarjet procedure, the internal rotation durability was significantly higher in the split group (p = 0.045). However, a statistically significant difference could not be found for internal and external rotational strengths (n.s.). There was also no significant difference between the final ASES and ROWE scores (n.s.). Although both approaches offer promising results, the subscapularis split approach appears to provide better internal rotation durability compared to subscapularis tenotomy. Therefore, the subscapularis split approach may be more preferable for the management of the subscapularis muscle during Latarjet procedure. Retrospective cohort study, Level III.

  9. INTEGRITY OF THE SUBSCAPULARIS TENDON AFTER OPEN SURGERY FOR THE TREATMENT OF ANTERIOR SHOULDER INSTABILITY: A CLINICAL AND RADIOLOGICAL EVALUATION

    PubMed Central

    Lech, Osvandré; Piluski, Paulo; Tambani, Renato; Castro, Nero; Pimentel, Gilnei

    2015-01-01

    Objective: To evaluate the integrity of the subscapularis tendon by strength, function and magnetic resonance imaging after deltopectoralis access for anterior shoulder instability. Methods: 20 patients with anterior shoulder instability have been evaluated. Minimum follow-up was 12 months, with a mean of 40 months. Only male patients were included, with a mean of age of 29 years (20 − 42 years). The patients have been submitted to physical examinations of mobility, muscular strength, Belly Test and Gerber Test. The isokinetic strength in internal and external rotation, in angular speeds of 600/s and 1800/s, for both shoulders was measured using a dynamometer. In 15 patients magnetic resonance imaging (MRI) was carried out on both shoulders for evaluating the thickness, cross-sectional area and atrophy of the subscapularis muscle. Results: A significant difference was found between torque peaks at the speed of 600/s for internal (p=0.036) and external (p=0.008) rotation. However, at 1800/s the opposite happens (internal rotation: p=0.133; external rotation: p=0.393). Subscapularis muscle thickness and area are significantly smaller than the normal side, with a deficit of 19% and 23%, respectively. According to Rowe and UCLA scores, we find excellent and good results for the majority of patients, with a mean of 88 and 31.6 points, respectively. Conclusion: Despite of the good functional results, open surgery can limit strength and reduce the thickness and the cross-sectional area of subscapularis muscle. However, the best results were found in the patients who had the dominant side operated. PMID:27004190

  10. Arthroscopic Bankart repair with knotless suture anchor for traumatic anterior shoulder instability: results of short-term follow-up.

    PubMed

    Hayashida, Kenji; Yoneda, Minoru; Mizuno, Naoko; Fukushima, Sunao; Nakagawa, Shigeto

    2006-06-01

    To assess the clinical results of arthroscopic Bankart repair with the knotless suture anchor for traumatic recurrent anterior shoulder instability. A total of 47 patients with traumatic recurrent anterior shoulder instability and without severe glenoid bone defect who underwent arthroscopic Bankart repair with knotless suture anchors and were followed-up for longer than 2 years were included in the present study. The average age at surgery was 26 years (range, 16 to 49 years), with an average follow-up period of 28 months (range, 24 to 38 months). Clinical score as evaluated by the modified Rowe score advanced from 31 points to 91 points. In all, 35 patients were scored as excellent and 6 as good; the success rate was 87% (41 of 47), and the recurrence rate was 6.4% (3 of 47). External rotation was reduced by 8 degrees at adduction and by 6 degrees at 90 degrees of abduction. Of 12 patients, 7 (58%) returned completely to collision sports at preinjury levels, and 2 of 12 (17%) returned at a lower level. We experienced anchor-related trouble in 3 cases. One was the backwardness of the anchor at 2 months after operation. Breakage of the anchor loop occurred during the procedures in 2 cases. The clinical results of arthroscopic Bankart repair with knotless suture anchor were favorable; however, some pitfalls, such as the backwardness of the anchor and cutting of the anchor loop, were experienced. When using this anchor, its properties should be well recognized. Level IV, therapeutic case series.

  11. Contribution of osseous and muscular stabilizing effects with the Latarjet procedure for anterior instability without glenoid bone loss.

    PubMed

    Dines, Joshua S; Dodson, Christopher C; McGarry, Michelle H; Oh, Joo Han; Altchek, David W; Lee, Thay Q

    2013-12-01

    The Latarjet procedure is used to treat anterior shoulder instability. Authors contend that the main concept of the operation is using the conjoined tendon as a sling to lower the subscapularis, reinforcing the anteroinferior capsule. The effects of the "sling," as well as stability and range of motion (ROM), after the Latarjet procedure have not been documented. In this study, we test the Latarjet procedure, attempting to account for the effect of the conjoined tendon. We also use the model to characterize the kinematic effects and stabilizing mechanism of the Latarjet procedure. Six cadaveric shoulders were tested in the intact state, after anterior capsulotomy, and after the Latarjet procedure. An apparatus was designed that allowed for loading of the conjoined tendon. ROM and translation were quantified. After conclusion of testing in the Latarjet group, the conjoined tendon was released and specimens were retested to determine stability attributable to the sling effect versus the osseous effect alone. We found no statistically significant differences with regard to ROM after the Latarjet procedure. The Latarjet procedure did significantly decrease anteroinferior translation. However, when the conjoined tendon was unloaded, there was a significantly decreased resistance to anterior translation. After conjoined tendon release, there was no effect on inferior translation. This study confirmed that the Latarjet procedure successfully decreases anteroinferior translation while maintaining ROM. It did not support the belief that inferior stability is provided by the sling effect. The model developed can serve as the basis for future testing. basic science study, biomechanics. Copyright © 2013 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Mosby, Inc. All rights reserved.

  12. Novel measure of articular instability based on contact stress confirms that the anterior cruciate ligament is a critical stabilizer of the lateral compartment.

    PubMed

    Imhauser, Carl W; Sheikh, Saad; Choi, Daniel S; Nguyen, Joseph T; Mauro, Craig S; Wickiewicz, Thomas L

    2016-03-01

    Knee instability following anterior cruciate ligament (ACL) rupture is common, compromising function, and causing cartilage and meniscal damage. In this study, instability at the level of the articular surfaces was characterized with a new measure: articular instability. Articular instability was defined as the change in location of the center of contact stress per unit of applied load. The effect of ACL-deficiency on articular instability was quantified in response to combined abduction and internal rotation moments simulating the clinical pivot shift, which recreates the sensation of instability. Eleven cadaver knees were loaded using a robotic manipulator and tibiofemoral contact stress was measured using a stress transducer. Sectioning the ACL led to pronounced articular instability on the lateral compartment in 4 of 11 knees. In these 4 knees articular instability increased posteriorly up to 403% and increased laterally up to 754%. Factors driving inter-specimen variations in articular instability might include articular morphology, ligamentous laxity, and the applied loads. This novel description of contact mechanics confirms that the ACL prevents sudden changes in the relative position of the lateral articular surfaces. It is applicable to any loading conditions and provides a unique measure to quantify the effects of ACL injury and reconstruction. © 2015 Orthopaedic Research Society. Published by Wiley Periodicals, Inc.

  13. Isolated anterior talofibular ligament Broström repair for chronic lateral ankle instability: 9-year follow-up.

    PubMed

    Maffulli, Nicola; Del Buono, Angelo; Maffulli, Gayle D; Oliva, Francesco; Testa, Vittorino; Capasso, Giovanni; Denaro, Vincenzo

    2013-04-01

    Lateral ankle sprains may result in pain and disability in the short term, decreased sport activity and early retirement from sports in the mid term, and secondary injuries and development of early osteoarthritis to the ankle in the long term. This combined approach to chronic lateral instability and intra-articular lesions of the ankle is safe and in the long term maintains mechanical stability, functional ability, and a good level of sport activity. Case series; Level of evidence, 4. We present the long-term outcomes of 42 athletes who underwent ankle arthroscopy and anterior talofibular Broström repair for management of chronic lateral ankle instability. We assessed in all patients preoperative and postoperative anterior drawer test and side-to-side differences, American Orthopaedic Foot and Ankle Society (AOFAS) score, and Kaikkonen grading scales. Patients were asked about return to sport and level of activity. Patients were also assessed for development of degenerative changes to the ankle, and preoperative versus postoperative findings were compared. Thirty-eight patients were reviewed at an average of 8.7 years (range, 5-13 years) after surgery; 4 patients were lost to follow-up. At the last follow-up, patients were significantly improved for ankle laxity, AOFAS scores, and Kaikkonen scales. The mean AOFAS score improved from 51 (range, 32-71) to 90 (range, 67-100), and the mean Kaikkonen score improved from 45 (range, 30-70) to 90 (range, 65-100). According to outcome criteria set preoperatively, there were 8 failures by the AOFAS score and 9 by the Kaikkonen score. Twenty-two (58%) patients practiced sport at the preinjury level, 6 (16%) had changed to lower levels but were still active in less demanding sports (cycling and tennis), and 10 (26%) had abandoned active sport participation although they still were physically active. Six of these patients did not feel safe with their ankle because of the occurrence of new episodes of ankle instability. Of the

  14. Management of mid-season traumatic anterior shoulder instability in athletes.

    PubMed

    Owens, Brett D; Dickens, Jonathan F; Kilcoyne, Kelly G; Rue, John-Paul H

    2012-08-01

    Shoulder dislocation and subluxation injuries are common in young athletes and most frequently occur during the competitive season. Controversy exists regarding optimal treatment of an athlete with an in-season shoulder dislocation, and limited data are available to guide treatment. Rehabilitation may facilitate return to sport within 3 weeks, but return is complicated by a moderate risk of recurrence. Bracing may reduce the risk of recurrence, but it restricts motion and may not be tolerated in patients who must complete certain sport-specific tasks such as throwing. Surgical management of shoulder dislocation or subluxation with arthroscopic or open Bankart repair reduces the rate of recurrence; however, the athlete is unable to participate in sport for the remainder of the competitive season. When selecting a management option, the clinician must consider the natural history of shoulder instability, pathologic changes noted on examination and imaging, sport- and position-specific demands, duration of treatment, and the athlete's motivation.

  15. Diagnostic accuracy of physical examination for anterior knee instability: a systematic review.

    PubMed

    Leblanc, Marie-Claude; Kowalczuk, Marcin; Andruszkiewicz, Nicole; Simunovic, Nicole; Farrokhyar, Forough; Turnbull, Travis Lee; Debski, Richard E; Ayeni, Olufemi R

    2015-10-01

    Determining diagnostic accuracy of Lachman, pivot shift and anterior drawer tests versus gold standard diagnosis (magnetic resonance imaging or arthroscopy) for anterior cruciate ligament (ACL) insufficiency cases. Secondarily, evaluating effects of: chronicity, partial rupture, awake versus anaesthetized evaluation. Searching MEDLINE, EMBASE and PubMed identified studies on diagnostic accuracy for ACL insufficiency. Studies identification and data extraction were performed in duplicate. Quality assessment used QUADAS tool, and statistical analyses were completed for pooled sensitivity and specificity. Eight studies were included. Given insufficient data, pooled analysis was only possible for sensitivity on Lachman and pivot shift test. During awake evaluation, sensitivity for the Lachman test was 89 % (95 % CI 0.76, 0.98) for all rupture types, 96 % (95 % CI 0.90, 1.00) for complete ruptures and 68 % (95 % CI 0.25, 0.98) for partial ruptures. For pivot shift in awake evaluation, results were 79 % (95 % CI 0.63, 0.91) for all rupture types, 86 % (95 % CI 0.68, 0.99) for complete ruptures and 67 % (95 % CI 0.47, 0.83) for partial ruptures. Decreased sensitivity of Lachman and pivot shift tests for partial rupture cases and for awake patients raised suspicions regarding the accuracy of these tests for diagnosis of ACL insufficiency. This may lead to further research aiming to improve the understanding of the true accuracy of these physical diagnostic tests and increase the reliability of clinical investigation for this pathology. IV.

  16. Risk factors which predispose first-time traumatic anterior shoulder dislocations to recurrent instability in adults: a systematic review and meta-analysis

    PubMed Central

    Olds, M; Ellis, R; Donaldson, K; Parmar, P; Kersten, P

    2015-01-01

    Background Recurrent instability following a first-time anterior traumatic shoulder dislocation may exceed 26%. We systematically reviewed risk factors which predispose this population to events of recurrence. Methods A systematic review of studies published before 1 July 2014. Risk factors which predispose recurrence following a first-time traumatic anterior shoulder dislocation were documented and rates of recurrence were compared. Pooled ORs were analysed using random-effects meta-analysis. Results Ten studies comprising 1324 participants met the criteria for inclusion. Recurrent instability following a first-time traumatic anterior shoulder dislocation was 39%. Increased risk of recurrent instability was reported in people aged 40 years and under (OR=13.46), in men (OR=3.18) and in people with hyperlaxity (OR=2.68). Decreased risk of recurrent instability was reported in people with a greater tuberosity fracture (OR=0.13). The rate of recurrent instability decreased as time from the initial dislocation increased. Other factors such as a bony Bankart lesion, nerve palsy and occupation influenced rates of recurrent instability. Conclusions Sex, age at initial dislocation, time from initial dislocation, hyperlaxity and greater tuberosity fractures were key risk factors in at least two good quality cohort studies resulting in strong evidence as concluded in the GRADE criteria. Although bony Bankart lesions, Hill Sachs lesions, occupation, physiotherapy treatment and nerve palsy were risk factors for recurrent instability, the evidence was weak using the GRADE criteria—these findings relied on poorer quality studies or were inconsistent among studies. PMID:25900943

  17. Biomechanical Evaluation of Glenoid Version and Dislocation Direction on the Influence of Anterior Shoulder Instability and Development of Hill-Sachs Lesions.

    PubMed

    Eichinger, Josef K; Massimini, Daniel F; Kim, Jungryul; Higgins, Laurence D

    2016-11-01

    Abnormal glenoid version is a risk factor for shoulder instability. However, the degree to which the variance in version (both anteversion and retroversion) affects one's predisposition for instability is not well understood. To determine the influence of glenoid version on anterior shoulder joint stability and to determine if the direction of the humeral head dislocation is a stimulus for the development of Hill-Sachs lesions. Controlled laboratory study. Ten human cadaveric shoulders (mean age, 59.4 ± 4.3 years) were tested using a custom shoulder dislocation device placed in a position of apprehension (90° of abduction with 90° of external rotation). Glenoid version was adjusted in 5° increments for a total of 6 version angles tested: +10°, +5°, 0°, -5°, -10°, and -15° (anteversion angles are positive, and retroversion angles are negative). Two humeral dislocation directions were tested. The first direction was true anterior through the anterior-posterior glenoid axis. The second dislocation direction was 35° inferior from the anterior-posterior glenoid axis based on the deforming force role of the pectoralis major. The force and energy to dislocate were recorded. Changes in glenoid version manifested a linear effect on the dislocation force. The energy to dislocate increased as a second-order polynomial as a function of increasing glenoid retroversion. Glenoid version of +10° anteversion and -15° retroversion was highly unstable, resulting in spontaneous dislocation in one-quarter (10/40) and one-half (25/40) of the specimens anteriorly and posteriorly, respectively, in the absence of an applied dislocation force. The greater tuberosity was observed to engage with the anterior glenoid rim, consistent with Hill-Sachs lesions, 40% more frequently when the dislocation direction was true anterior compared with 35° inferior from the anterior-posterior glenoid axis. The engagement of the greater tuberosity caused an increase in the energy required to

  18. Clinical Application of the "Glenoid Track" Concept for Defining Humeral Head Engagement in Anterior Shoulder Instability: A Preliminary Report.

    PubMed

    Metzger, Paul D; Barlow, Brian; Leonardelli, Dominic; Peace, William; Solomon, Daniel J; Provencher, Matthew T

    2013-07-01

    The optimal treatment of Hill-Sachs injuries is difficult to determine and is potentiated by the finding that a Hill-Sachs injury becomes more important in the setting of glenoid bone loss, making engagement of the humeral head on the glenoid inherently easier. The "glenoid track" concept was developed to biomechanically quantify the effects of a combined glenoid and humeral head bony defects on instability. To clinically evaluate humeral head engagement on the glenoid by utilizing glenoid track measurements of both humeral head and glenoid bone loss. Retrospective cohort. A total of 205 patients with recurrent anterior shoulder instability were evaluated, and of these, 140 patients (68%; 9 females [6%] and 131 males [94%]) with a Hill-Sachs lesion and a mean age of 27.6 years (range, 15-47 years; standard error of mean [SEM], 0.59) were included in the final magnetic resonance angiogram [MRA]) analysis. Bipolar bone loss measures of glenoid bone loss (sagittal oblique MRA) and multiple size measures of the Hill-Sachs injury (coronal, axial, and sagittal MRA) were recorded. Based on the extent of the bipolar lesion, patients were classified with glenoid track as either outside and engaging of the glenoid on the humeral head (OUT-E) or inside and nonengaging (IN-NE). The 2 groups were then compared with clinical evidence of engagement on examination under anesthesia (EUA) using video arthroscopy, number of dislocations, length of instability, and patient age. The mean glenoid bone loss was 7.6% (range, 0%-29%; SEM, 1.20%), and 31 of 140 (22%) patients demonstrated clinical engagement on EUA. Radiographically, 19 (13.4%) patients were determined to be OUT-E, while 121 (86.6%) were IN-NE and not expected to engage. Of those 19 patients with suggested radiographic engagement (OUT-E), 16 (84.5%) had clinical evidence of engagement versus only 12.4% that clinically engaged (15/121) without radiographic evidence of engagement (IN-NE) (P < .001). Younger age and a greater

  19. “8 Plate”: An Alternative Device to Fix Highly Recurrent Traumatic Anterior Gleno-Humeral Instability in Patients with Severe Impairment of the Anterior Capsule

    PubMed Central

    Tudisco, C; Bisicchia, S; Savarese, E; Ippolito, E

    2014-01-01

    Background: There is still debate about the best treatment option for highly recurrent anterior shoulder dislocation in patients with severe impairment of the anterior capsule and/or recurrence after either arthroscopic or open capsulorrhaphy. Materials and Methods: The clinical and radiological findings of 7 patients treated with an open capsulorrhaphy stabilized with an “8 plate” for a highly recurrent traumatic anterior shoulder dislocation with severe impairment of the anterior capsule and a large Bankart lesion were retrospectively reviewed. Follow-up evaluation included VAS for pain, Constant-Murley, Simple Shoulder Test, ASES, UCLA, Quick DASH, Rowe, Walsch-Duplay scores, as well as X-rays of the operated shoulder. Results: At follow-up none of the patients reported subsequent dislocations. Range of motion of the shoulder was complete in all cases, but one. Results of the functional scoring systems were satisfactory. X-rays showed no osteolysis and good position of the plate. Conclusion: To our knowledge, this is the first report in the literature about an open capsular tensioning and Bankart lesion repair performed with an “8 plate”. We believe that this is a reliable and effective procedure to address traumatic anterior re-dislocation of the gleno-humeral joint when the capsule is extensively torn and frayed or in revision cases. Moreover the “8 plate” is ideal to be applied in such a narrow space on the slant surface of the scapular neck close to the glenoid rim. PMID:25621080

  20. Open Bankart Repair for the Treatment of Anterior Shoulder Instability without Substantial Osseous Glenoid Defects: Results After a Minimum Follow-up of Twenty Years.

    PubMed

    Moroder, Philipp; Odorizzi, Marco; Pizzinini, Severino; Demetz, Ernst; Resch, Herbert; Moroder, Peter

    2015-09-02

    Neglected osseous glenoid defects are thought to be one of the reasons for the reported high rates of recurrent instability at long-term follow-up after Bankart repair. We hypothesized that open Bankart repair for the treatment of anterior glenohumeral instability in the absence of a substantial osseous glenoid defect would result in a lower long-term recurrence rate than has been reported in previous long-term studies. Forty-seven patients were treated with a primary modified open Bankart repair for recurrent anterior shoulder instability between 1989 and 1994. Double-contrast computed tomography scanning was used to exclude patients with a substantial osseous glenoid defect. Forty patients (85.1%) were available for subjective and objective follow-up at a minimum of twenty years (maximum, twenty-five years). Twenty-six patients (65%) underwent clinical examination as well as bilateral shoulder radiography, and fourteen (35%) completed a self-assessment questionnaire and were interviewed by telephone. Seven patients (17.5%) had a recurrence of instability, and six of them had the instability occur after more than eight years without symptoms. The mean Western Ontario Shoulder Instability Index score (and standard deviation) was 256.7 ± 284.8 points; the mean Rowe score, 88.7 ± 12.0 points; and the mean Subjective Shoulder Value, 90.1% ± 10.5%.The mean range of motion of the affected shoulder was decreased by 4° of abduction (p = 0.009), two levels of internal rotation (p = 0.003), 5° of internal rotation in 90° of abduction (p = 0.005), 7° of external rotation in neutral position (p < 0.001), and 7° of external rotation in 90° of abduction (p = 0.004) compared with the contralateral side. The collective instability arthropathy (CIA) index was 0.92 for the affected side and 0.35 for the contralateral side. Open Bankart repair provides good results twenty years after surgery in terms of subjective and objective outcome measurements. However, the long

  1. The Latarjet procedure for the treatment of recurrence of anterior instability of the shoulder after operative repair: a retrospective case series of forty-nine consecutive patients.

    PubMed

    Schmid, Samuel L; Farshad, Mazda; Catanzaro, Sabrina; Gerber, Christian

    2012-06-06

    Recurrence of anterior shoulder instability after operative repair is an uncommon but disabling condition for which treatment options have been insufficiently studied. Coracoid transfer as described by Latarjet is a highly successful primary operation for recurrent anterior shoulder instability. The purpose of this study was to verify the hypothesis that this procedure is also effective for treating recurrent glenohumeral instability after previous operative repair. Forty-nine consecutive patients with either one (n = 32), two (n = 12), or at least three (n = 5) previous stabilizations other than a Latarjet procedure and recurrence of anterior glenohumeral instability associated with a lesion of the anterior aspect of the glenoid rim had revision with a coracoid transfer as described by Latarjet. Clinical outcomes at a mean of thirty-eight months postoperatively included the subjective shoulder value, the Constant-Murley score, and glenohumeral stability. Standardized anteroposterior and axial radiographs before and after the Latarjet revision were used to grade the degree of glenohumeral osteoarthritis. The results in all forty-nine patients were reviewed. No shoulder redislocated, subluxations recurred in two patients, and five patients reported slight, unspecified shoulder symptoms. No revision surgery was needed. Forty-three shoulders (88%) were subjectively graded as excellent or good; three, fair; and three, poor. Dissatisfaction was associated with persistent pain, and patients with preoperative pain had a twentyfold higher probability of having postoperative pain. The mean subjective shoulder value increased from 53% preoperatively to 79% at the time of follow-up (p < 0.001), and the Constant-Murley score remained high (80% preoperatively and 85% at the time of follow-up; p = 0.061). Optimal graft placement was obtained in thirty cases and was related to better clinical outcome and less progression of osteoarthritis than was suboptimal graft placement

  2. Profile of collagen gene expression in the glenohumeral capsule of patients with traumatic anterior instability of the shoulder☆☆☆

    PubMed Central

    Belangero, Paulo Santoro; Leal, Mariana Ferreira; de Castro Pochini, Alberto; Andreoli, Carlos Vicente; Ejnisman, Benno; Cohen, Moises

    2014-01-01

    Objective To evaluate the expression of the genes COL1A1, COL1A2, COL3A1 and COL5A1 in the glenohumeral capsule of patients with traumatic anterior instability of the shoulder. Methods Samples from the glenohumeral capsule of 18 patients with traumatic anterior instability of the shoulder were evaluated. Male patients with a positive grip test and a Bankart lesion seen on magnetic resonance imaging were included. All the patients had suffered more than one episode of shoulder dislocation. Samples were collected from the injured glenohumeral capsule (anteroinferior region) and from the macroscopically unaffected region (anterosuperior region) of each patient. The expression of collagen genes was evaluated using the polymerase chain reaction after reverse transcription with quantitative analysis (qRT-PCR). Results The expression of COL1A1, COL1A2 and COL3A1 did not differ between the two regions of the shoulder capsule. However, it was observed that the expression of COL5A1 was significantly lower in the anteroinferior region than in the anterosuperior region (median ± interquartile range: 0.057 ± 0.052 vs. 0.155 ± 0.398; p = 0.028) of the glenohumeral capsule. Conclusion The affected region of the glenohumeral capsule in patients with shoulder instability presented reduced expression of COL5A1. PMID:26229875

  3. Painful patellofemoral instability secondary to peroperative patellar fracture during bone-patellar tendon-bone autograft harvesting for anterior cruciate ligament reconstruction.

    PubMed

    Vidal, C; Guingand, O; de Thomasson, E; Conso, C; Terracher, R; Balabaud, L; Mazel, C

    2012-10-01

    Reconstructive surgery of the anterior cruciate ligament (ACL) of the knee in young active patients is a routine procedure, but with certain risks that need to be taken into account. Peroperative patellar fracture after bone-patellar tendon-bone autograft harvesting is a rare complication, which can significantly impair the functional outcome of ACL single-bundle reconstruction. We report the case of a patient presenting with disabling patellofemoral syndrome 3 years after arthroscopic ACL reconstruction by bone-tendon-bone autograft, revealing unnoticed mal-union of a iatrogenic sagittal patellar fracture. Patellar osteotomy corrected this painful iatrogenic patellar instability. Copyright © 2012 Elsevier Masson SAS. All rights reserved.

  4. Double-Barrel Remplissage: An Arthroscopic All-Intra-articular Technique Using the Double-Barrel Knot for Anterior Shoulder Instability.

    PubMed

    Bhatia, Deepak N

    2015-02-01

    The arthroscopic remplissage procedure is an effective addition to a standard anterior repair in traumatic anterior shoulder instability associated with large humeral defects. The double-barrel remplissage is an all-intra-articular technique that uses a double-pulley, sliding, and self-retaining knot mechanism called the double-barrel knot. A 70° arthroscope (posterior portal) is necessary for adequate visualization of the humeral defect and the rotator cuff. Trans-tendon anchors (single or double loaded) are inserted into the superior and inferior aspects of the humeral defect through a cannula that is placed posterior to the infraspinatus. Placement of anchors is facilitated by insertion of a guidewire, as well as an anchor sleeve that is threaded over it. The double-barrel knot is formed using the anchors as a double-pulley system, and the knot is tensioned after the anterior repair is complete. Intra-articular visualization confirms adequate approximation and compression of the infraspinatus tendon and capsule into the defect. Advantages include an increased surface area (footprint) for healing and ease of knotting without the necessity for additional subacromial dissection.

  5. Bone fragment union and remodeling after arthroscopic bony bankart repair for traumatic anterior shoulder instability with a glenoid defect: influence on postoperative recurrence of instability.

    PubMed

    Nakagawa, Shigeto; Ozaki, Ritsuro; Take, Yasuhiro; Mae, Tatsuo; Hayashida, Kenji

    2015-06-01

    Although good clinical outcomes have been reported after arthroscopic bony Bankart repair, the extent of bone union is still unclear. To investigate bone union after arthroscopic bony Bankart repair and its influence on postoperative recurrence of instability. Cohort study; Level of evidence, 3. Among 113 consecutive shoulders that underwent arthroscopic bony Bankart repair, postoperative evaluation of bone union by computed tomography (CT) was performed at various times in 81 shoulders. Bone union was investigated during 3 periods: 3 to 6 months postoperatively (first period), 7 to 12 months postoperatively (second period), and 13 months or more postoperatively (third period). The influence of the size of the preoperative glenoid defect and the size of the bone fragment on bone union was investigated, as well as the influence of bone union on postoperative recurrence of instability. In shoulders with bone union, bone fragment remodeling and changes in the glenoid defect size were also investigated. The bone union rate was 30.5% in the first period, 55.3% in the second period, and 84.6% in the third period. Among 53 shoulders with CT evaluation in the second period or later and follow-up for a minimum of 1 year, there was complete union in 33 shoulders (62.3%), partial union in 3 (5.7%), nonunion in 8 (15.1%), and no fragment on CT in 9 (17.0%). The complete union rate was 50% for 22 shoulders with small bone fragments (<5% of the glenoid diameter), 56.3% for 16 shoulders with medium fragments (5%-10%), and 86.7% for 15 shoulders with large fragments (>10%). The recurrence rate for postoperative instability was only 6.1% for shoulders with complete union, while it was 50% for shoulders with partial union, nonunion, no fragment, and no fragment on CT. The recurrence rate was significantly higher (36.4%) in shoulders with small fragments, but it was significantly lower in shoulders with bone union. In shoulders with bone union, the bone fragment frequently became

  6. Clinical and Anatomic Predictors of Outcomes After the Latarjet Procedure for the Treatment of Anterior Glenohumeral Instability With Combined Glenoid and Humeral Bone Defects.

    PubMed

    Mook, William R; Petri, Maximilian; Greenspoon, Joshua A; Horan, Marilee P; Dornan, Grant J; Millett, Peter J

    2016-06-01

    The Latarjet procedure for the treatment of recurrent anterior shoulder instability is highly successful, but reasons for failure are often unclear. Measurements of the "glenoid track" have not previously been evaluated as potential predictors of postoperative stability. There are clinical and anatomic characteristics, including the glenoid track, that are predictive of outcomes after the Latarjet procedure. Case series; Level of evidence, 4. Patients who underwent the Latarjet procedure for anterior shoulder instability with glenoid bone loss before October 2012 were assessed for eligibility. Patient-reported subjective data that were prospectively collected and retrospectively reviewed included demographic information, patient satisfaction, pain measured on a visual analog scale (VAS), questions regarding instability, Single Assessment Numeric Evaluation (SANE) scores, American Shoulder and Elbow Surgeons (ASES) scores, Quick Disabilities of the Arm, Shoulder and Hand (QuickDASH) scores, and Short Form-12 Physical Component Summary (SF-12 PCS) scores. Anatomic measurements were performed of the coracoid size (surface area and width), width of the conjoined tendon and subscapularis tendon, estimated glenoid defect surface area, Hill-Sachs interval (HSI), and projected postoperative glenoid track engagement. Failure was defined as the necessity for revision stabilization or continued instability (dislocation or subjective subluxation) at a minimum of 2 years postoperatively. A total of 38 shoulders in 38 patients (33 men, 5 women) with a mean age of 26 years (range, 16-43 years) were included. The mean follow-up for 35 of 38 patients (92%) was 3.2 years (range, 2.0-7.9 years); 25 of 38 had undergone prior stabilization surgery, and 6 had workers' compensation claims. All mean subjective outcome scores significantly improved (P < .05), with a high median satisfaction score of 9 of 10. Eight patients had failures because of continued instability. Patients with

  7. A comparison of dynamic rotational knee instability between anatomic single-bundle and over-the-top anterior cruciate ligament reconstruction using triaxial accelerometry.

    PubMed

    Asai, Shigehiro; Maeyama, Akira; Hoshino, Yuichi; Goto, Bunsei; Celentano, Umberto; Moriyama, Shigeaki; Smolinski, Patrick; Fu, Freddie H

    2014-05-01

    Recently, single-bundle (SB) anterior cruciate ligament (ACL) reconstruction has been advanced by the anatomic concept, but the biomechanical outcome of the anatomic method has not been fully investigated, especially for rotational instability. Anatomic SB and the single over-the-top procedures are the treatment of choice for primary cases and revision or skeletally immature cases, respectively. The purpose of this study was to investigate the dynamic rotational instability of anatomic SB and over-the-top reconstruction during a pivot shift test using triaxial accelerometry. Eight fresh frozen human cadaveric knees were used in this study. Rotational instability measurement was conducted during a pivot shift test by the use of a triaxial accelerometer attached to the tibia. The tests were performed in the ACL-intact, ACL-deficient and ACL-reconstructed knees with two different procedures (anatomic SB and over-the-top). The acceleration in three directions and the magnitude of acceleration were measured to evaluate rotational instability and compare between four different knee states. The overall magnitude of acceleration was significantly different (P < 0.01) between the ACL-intact knees and the ACL-deficient knees. Both anatomic SB and over-the-top ACL reconstruction significantly reduced the overall magnitude of acceleration compared to the ACL-deficient knees, but still had larger accelerations compared to the ACL-intact knees. There was no significant difference for the overall magnitude of acceleration between anatomic SB and over-the-top reconstruction procedure. Over-the-top reconstruction provides comparable result to anatomic SB reconstruction in terms of controlling the dynamic rotational stability. Over-the-top reconstruction might be one of the options for revision cases and in skeletally immature patients.

  8. Arthroscopic Bankart repair associated with subscapularis augmentation (ASA) versus open Latarjet to treat recurrent anterior shoulder instability with moderate glenoid bone loss: clinical comparison of two series.

    PubMed

    Russo, R; Della Rotonda, G; Cautiero, F; Ciccarelli, M; Maiotti, M; Massoni, C; Di Pietto, F; Zappia, M

    2017-04-01

    The treatment of chronic anterior shoulder instability with glenoid bone loss is still debated. The purpose of this study is to compare short-term results of two techniques treating chronic shoulder instability with moderate glenoid bone loss: bone block according to open Latarjet-Patte procedure and arthroscopic Bankart repair in association with subscapularis augmentation. Ninety-one patients with moderate anterior glenoid bone loss underwent from 2011 to 2015. From these patients, two groups of 20 individuals each have been selected. The groups were homogeneous in terms of age, gender, dominance and glenoid bone loss. In group A, an open Latarjet procedure has been performed, and in group B, an arthroscopic Bankart repair associated with subscapularis augmentation has been performed. The mean follow-up in group A was 21 months (20-39 months), while in group B was 20 months (15-36 months). QuickDash score, Constant and Rowe shoulder scores, were used for evaluations of results. The mean preoperative rate of QuickDash score was 3.6 for group A and 4.0 for group B; Rowe Score was 50.0 for group A and 50.0 for group B. Preoperative mean Constant score was 56.2 for Latarjet-Patte and 55.2 for Bankart plus ASA. Postoperative mean QuickDash score was in group A 1.8 and 1.7 in group B; Rowe Score was 89.8 and 91.6; Constant Score was 93.3 and 93.8. No complications related to surgery have been observed for both procedures. Not statistically significant difference was reported between the two groups (p > .05). Postoperatively, the mean deficit of external rotation in ER1 was -9° in group A and -8 in group B; In ER2, the mean deficit was -5° in both groups (p = .0942). Arthroscopic subscapularis augmentation of Bankart repair is an effective procedure for the treatment of recurrent anterior shoulder instability with glenoid bone loss without any significant difference in comparison with the well-known open Latarjet procedure.

  9. Open Bankart repair with suture anchors for traumatic recurrent anterior shoulder instability: comparison of results between small and large Bankart lesions.

    PubMed

    Lai, Davy; Ma, Hsiao-Li; Hung, Shih-Chieh; Chen, Tain-Hsiung; Wu, Jiunn-Jer

    2006-01-01

    This retrospective study was to demonstrate the clinical outcome of open Bankart repair with suture anchors for recurrent anterior shoulder instability, and to compare surgical results of small (<3 clock units) and large (>3 clock units) Bankart lesions. With an average follow-up of 55.6 months (2-8 years), there were 82 patients (60 right, 22 left shoulders) with the mean age of 27 years accepting open Bankart repair with suture anchors and capsular shift procedure by the same team. According to surgical findings, these patients were grouped into small (<3 clock units) and large (>3 clock units) Bankart lesions. Subjective outcomes were recorded according to the Bankart scoring system of Rowe. Rowe scores averaged 85.9+/-12.9 (range 25-100). The patients, 92-7 %, had objectively excellent or good results. Twenty nine patients (35.4%) had small Bankart lesions and 53 patients had large Bankart lesions. The Rowe scores in small Bankart lesions were better than that in large Bankart lesions (93.5+/-6.8 vs. 81.8+/-13.6, Wilcoxon rank sum test, P<0.001). Mean scores of stability (Wilcoxon rank sum test, P=0.043), motion (Wilcoxon rank sum test, P=0.037), and function (Wilcoxon rank sum test, P<0.001) in small lesions also had superior outcomes than in large lesions. Four patients (4.9%) got fair results and two (2.4%) patients got poor results at the end of follow-up. The average loss of external rotation is 10 degrees . Open Bankart repair with the aid of suture anchors still got satisfactory results in the treatment of traumatic recurrent anterior instability of the shoulder. The size of the Bankart lesion was a factor affecting surgical outcome. Small Bankart lesions usually got better results than large Bankart lesions.

  10. Return to sports after arthroscopic capsulolabral repair using knotless suture anchors for anterior shoulder instability in soccer players: minimum 5-year follow-up study.

    PubMed

    Alentorn-Geli, Eduard; Álvarez-Díaz, Pedro; Doblas, Jesús; Steinbacher, Gilbert; Seijas, Roberto; Ares, Oscar; Boffa, Juan José; Cuscó, Xavier; Cugat, Ramón

    2016-02-01

    To report the return to sports and recurrence rates in competitive soccer players after arthroscopic capsulolabral repair using knotless suture anchors at a minimum of 5 years of follow-up. All competitive soccer players with anterior glenohumeral instability treated by arthroscopic capsulolabral repair using knotless suture anchors between 2002 and 2009 were retrospectively identified through the medical records. Inclusion criteria were: no previous surgical treatment of the involved shoulder, absence of glenoid or tuberosity fractures, absence of large Hill-Sachs or glenoid bone defect, minimum follow-up of 5 years, instability during soccer practice or games, and failure of non-surgical treatment. The charts of included players were reviewed, and a phone call was performed in a cross-sectional manner to obtain information on: current soccer, return to soccer, recurrence of instability, shoulder function (Rowe score), and disability [Quick-Disability of the Arm, Shoulder, and Hand (DASH) score and Quick-DASH Sports/Performing Arts Module]. Fifty-seven young male soccer players were finally included with a median (range) follow-up of 8 (5-10) years. Forty-nine (86 %) of the soccer players were able to return to soccer and 36 of them (73 %) at the same pre-injury level. There were 6 (10.5 %) re-dislocations in the 57 players, all of them of traumatic origin produced during soccer and other unrelated activities. The main reasons to not return to soccer were: knee injuries (two players), changes in personal life (two players), and job-related (three players). None of the players quit playing soccer because of their shoulder instability injury. The median (range) Rowe score, Quick-DASH score, and Quick-DASH sports score were 80 (25-100), 2.3 (0-12.5), and 0 (0-18.8), respectively. Competitive soccer players undergoing arthroscopic capsulolabral repair with knotless suture anchors for shoulder instability without significant bone loss demonstrate excellent return to

  11. The Degree of Shoulder Involvement in Sports (DOSIS) scale is a valid and responsive instrumentation for shoulder assessment in patients after surgery for anterior instability.

    PubMed

    Vascellari, Alberto; Ramponi, Carlo; Venturin, Davide; Ben, Giulia; Blonna, Davide; Coletti, Nicolò

    2017-07-18

    The purpose of this study was to evaluate validity and responsiveness of the Degree of Shoulder Involvement in Sport (DOSIS) scale. A web-based survey was developed to test the construct validity of the DOSIS scale. Fifty-three patients with a median age of 33 years (range 17-59) were included in the study. Convergent validity was evaluated by external correlation (Spearman's rank correlation coefficient, r) of the DOSIS with the Brophy-Marx and Tegner activity scales, the Western Ontario shoulder instability index (WOSI), the Simple Shoulder Test (SST), and the Short-Form 36 (SF-36). Responsiveness was analysed by relative efficiency calculation of the DOSIS versus the Brophy-Marx and Tegner activity scales. The DOSIS showed strong correlation with the Brophy-Marx and Tegner activity scales, a moderate correlation with the WOSI and SST scores, and a moderate correlation with the physical functioning, role physical and role emotional subscores of the SF-36. The distribution of the DOSIS scores had no serious ceiling or floor effects. The DOSIS demonstrated lesser responsiveness when compared to the Brophy-Marx and Tegner activity scales. The DOSIS showed an adequate validity and responsiveness. The clinical relevance of this study is that the DOSIS scale can be used for sport-specific shoulder assessment in patients after surgery for anterior instability. III.

  12. A Comparison of Glenohumeral Internal and External Range of Motion and Rotation Strength in healthy and Individuals with Recurrent Anterior Instability.

    PubMed

    Sadeghifar, Amirreza; Ilka, Shahab; Dashtbani, Hasan; Sahebozamani, Mansour

    2014-09-01

    The glenohumeral joint becomes dislocated more than any other major joint because it maintains a wide range of motion and its stability is inherently weak. The most common complication following acute initial shoulder dislocation is recurrent dislocation or chronic instability. Imbalance of strength and range of motion in individuals with anterior dislocation can be a contributing factor in recurrent dislocation as well. This case-control study consisted of 24 individuals with a mean age of 24.29±4.33 years, and a mean dislocation rate of 5.37±3.62 times. Isometric cuff strength was measured using a handheld dynamometer and for range of motion, the Leighton flexometer was used in internal and external rotational motions of both upper extremities. Independent t-test was used for data analysis. The internal and external range of motion of the injured glenohumeral joint was lower than the uninjured joint (P<0.001). Similarly, the internal and external rotation strength of the injured joint was lower than the uninjured joint (P<0.001). According to previous data, imbalance of strength and range of motion in individuals with anterior shoulder dislocation can be a contributing factor in long-term disability and increased recurrent dislocation and our finding confirm decreased range of motion and strength in our patients. Hence, proper exercise and rehabilitation plans need to be developed for those suffering from this complication.

  13. Effect of Bankart repair on the loss of range of motion and the instability of the shoulder joint for recurrent anterior shoulder dislocation.

    PubMed

    Shibano, Koji; Koishi, Hayato; Futai, Kazuma; Yoshikawa, Hideki; Sugamoto, Kazuomi

    2014-06-01

    Bankart repair postoperative complications include loss of shoulder motion and shoulder instability. The primary reason that postoperative complications develop may be excessive imbrication of the anterior band of the inferior glenohumeral ligament (AIGHL) or inadequate repair position. The purpose of this study was to quantitatively evaluate the influence of inadequate repair by computer simulation for a normal shoulder joint. Magnetic resonance images of 10 normal shoulder joints were acquired for 7 positions every 30° from the maximum internal rotation to the maximum external rotation with the arm abducted at 90°. The shortest 3-dimensional path of the AIGHL in each rotational orientation was calculated. We used computer simulations to anticipate the loss of motion and instability by changing the AIGHL length and insertion sites on the glenoid. The AIGHL length measured 50 ± 5 mm at the maximum external shoulder rotation. AIGHL shortening by 3, 6, and 9 mm made the angle of maximum external rotation 80°, 68°, and 54°, respectively. A superior deviation of 3, 6, and 9 mm on the glenoid insertion resulted in a maximum external rotation angle of 85°, 79°, and 77°. An inferior deviation of 3, 6, and 9 mm produced humeral head translation of 1.7, 2.9, and 3.6 mm. Simulation of both excessive imbrication and deviation of the insertion position led to quantitative prediction of the resulting loss of motion and instability. These findings will be useful for anticipating complications after Bankart repair. Basic science study, computer modeling, imaging. Copyright © 2014. Published by Mosby, Inc.

  14. Arthroscopic Subscapularis Augmentation of Bankart Repair in Chronic Anterior Shoulder Instability With Bone Loss Less Than 25% and Capsular Deficiency: Clinical Multicenter Study.

    PubMed

    Maiotti, Marco; Massoni, Carlo; Russo, Raffaele; Schroter, Steffen; Zanini, Antonio; Bianchedi, Diana

    2017-05-01

    To assess the short-term outcomes of the arthroscopic subscapularis augmentation (ASA) technique, consisting of a tenodesis of the upper third of the subscapularis tendon and a Bankart repair, and its effect on shoulder external rotation. Patients selected for this study were involved in contact sports, with a history of traumatic recurrent shoulder dislocations and a minimum of 2-year follow-up. Inclusion criteria were patients with glenoid bone loss (GBL) ranging from 5% to 25%, anterior capsular deficiency, and Hill-Sachs lesion who underwent ASA technique. Exclusion criteria were GBL >25%, multidirectional instability, preexisting osteoarthritis, and overhead sports activities. Visual analog scale (VAS) scale for pain, Rowe score, and American Shoulder and Elbow Surgeons (ASES) scores were used to assess results. Loss of shoulder external rotation was measured with the arm at the side (ER1 position) or 90° in abduction (ER2 position). Analysis of variance and Fisher tests were used for data evaluation. Significance was established at P ≤ .05. One hundred ten patients (84 men and 26 women, mean age 27 years) were evaluated with a mean follow-up of 40.5 months (range: 24 to 65 months). In 98 patients, a Hill-Sachs lesion was observed and in 57 patients a capsular deficiency was present. Three patients (2.7%) had a traumatic redislocation. At final follow-up, the mean scores were as follows: VAS scale decreased from a mean of 3.5 to 0.5 (P = .015), Rowe score increased from 57.4 to 95.3 (P = .035), and ASES score increased from 66.5 to 96.5 (P = .021). The mean deficit of external rotation was 8° ± 2.5° in the ER1 position and 4° ± 1.5° in the ER2 position. The ASA procedure has been shown to be effective in restoring joint stability in patients practicing sports, affected by chronic anterior shoulder instability associated with anterior GBL (<25%), capsular deficiency, and Hill-Sachs lesions, with mild restriction of external rotation. Level IV

  15. Simultaneous surgical management of chronic grade-2 valgus instability of the knee and anterior cruciate ligament deficiency in athletes.

    PubMed

    Osti, Leonardo; Papalia, Rocco; Del Buono, Angelo; Merlo, Franco; Denaro, Vincenzo; Maffulli, Nicola

    2010-03-01

    We report on 22 patients with chronic grade-2 valgus laxity of the knee combined with chronic anterior cruciate ligament (ACL) insufficiency, in whom the two lesions were addressed at the same surgical setting. At a minimum follow-up of 24 months, clinical and functional variables had improved significantly (P < 0.001), and 20 of the 22 patients (91%) had returned to sport at pre-injury level. There were no operative complications in this series. In selected athletes with chronic symptomatic valgus laxity of the knee combined with ACL insufficiency, surgical repair of the MCL in association with ACL reconstruction is a suitable and reliable option to restore knee stability and allow return to pre-injury activity level.

  16. The Influence of Evidence-Based Surgical Indications and Techniques on Failure Rates After Arthroscopic Shoulder Stabilization in the Contact or Collision Athlete With Anterior Shoulder Instability.

    PubMed

    Leroux, Timothy S; Saltzman, Bryan M; Meyer, Maximilian; Frank, Rachel M; Bach, Bernard R; Cole, Brian J; Romeo, Anthony A; Verma, Nikhil N

    2017-04-01

    It has been reported that arthroscopic shoulder stabilization yields higher rates of failure in contact or collision athletes as compared with open shoulder stabilization; however, this is largely based upon studies that do not employ modern, evidence-based surgical indications and techniques for arthroscopic shoulder stabilization. To (1) determine the pooled failure rate across all studies reporting failure after primary arthroscopic shoulder stabilization for anterior shoulder instability in contact or collision athletes and (2) stratify failure rates according to studies that use evidence-based surgical indications and techniques. Systematic review. A review of PubMed, Medline, and Embase was performed to identify all clinical studies with a minimum of 1-year follow-up that reported failure rates after arthroscopic shoulder stabilization for anterior shoulder instability in contact or collision athletes. Data pertaining to patient demographics, clinical and radiographic preoperative assessment, surgical indications, surgical technique, rehabilitation, and outcome were collected from each included study. An overall failure rate was determined across all included studies. After this, a secondary literature review was performed to identify factors related to patient selection and surgical technique that significantly influence failure after primary arthroscopic shoulder stabilization. Failure rates were then determined among included studies that used these evidence-based indications and techniques. Overall, 26 studies reporting on 779 contact or collision athletes met the inclusion criteria. The mean patient age was 19.9 years, 90.3% were male, and the most common sport was rugby. There was considerable variability in the reporting of patient demographics, preoperative assessment, surgical indications, surgical technique, and patient outcomes. Across all included studies, the pooled failure rate after arthroscopic shoulder stabilization in the contact or

  17. Results of Arthroscopic Bankart Lesion Repair in Patients with Post-Traumatic Anterior Instability of the Shoulder and a Non-Engaging Hill-Sachs Lesion with a Suture Anchor after a Minimum of 6-Year Follow-Up

    PubMed Central

    Szyluk, Karol; Jasiński, Andrzej; Widuchowski, Wojciech; Mielnik, Michał; Koczy, Bogdan

    2015-01-01

    Background Shoulder instability is an important clinical problem. Arthroscopic surgery is an established treatment modality in shoulder instability, but it continues to be associated with a high rate of recurrences and complications. The purpose of the study was to analyze late outcomes of arthroscopic repair of Bankart lesions in patients with post-traumatic anterior shoulder instability and non-engaging Hill-Sachs lesion, with special focus on the incidence and causes of recurrences and complications. Material/Methods We investigated 92 patients (92 shoulders) who underwent surgery on account of post-traumatic anterior shoulder instability. The duration of follow-up ranged from 6 to 12.5 years (mean: 8.2 years). All patients were operated on in the lateral decubitus position using FASTak 2.8-mm suture anchors (FASTak, Arthrex, Naples, Florida). Treatment outcomes were evaluated using the Rowe and University of California at Los Angeles rating system (UCLA). Results According to Rowe scores, there were 71 (81.5%) excellent, 12 (12.6%) good, 5 (5.3%) satisfactory, and 2 (2.1%) poor results. Rowe scores improved in a statistically significant manner (p=0.00) post-surgery, to a mean of 90 (range: 25–100). Treatment outcomes measured as UCLA scores improved in a statistically significant manner (p=0.00), reaching post-operative levels of 12–35 (mean: 33.5). There were 9 recurrences, 1 case of axillary nerve praxia, and 1 case of anchor loosening. Conclusions With rigorous criteria for qualifying patients for surgery, arthroscopic treatment of post-traumatic anterior shoulder instability produces good outcomes and low recurrence and complication rates irrespective of the number of previous dislocations, age, or sex. PMID:26256225

  18. Results of Arthroscopic Bankart Lesion Repair in Patients with Post-Traumatic Anterior Instability of the Shoulder and a Non-Engaging Hill-Sachs Lesion with a Suture Anchor after a Minimum of 6-Year Follow-Up.

    PubMed

    Szyluk, Karol; Jasiński, Andrzej; Widuchowski, Wojciech; Mielnik, Michał; Koczy, Bogdan

    2015-08-10

    Shoulder instability is an important clinical problem. Arthroscopic surgery is an established treatment modality in shoulder instability, but it continues to be associated with a high rate of recurrences and complications. The purpose of the study was to analyze late outcomes of arthroscopic repair of Bankart lesions in patients with post-traumatic anterior shoulder instability and non-engaging Hill-Sachs lesion, with special focus on the incidence and causes of recurrences and complications. We investigated 92 patients (92 shoulders) who underwent surgery on account of post-traumatic anterior shoulder instability. The duration of follow-up ranged from 6 to 12.5 years (mean: 8.2 years). All patients were operated on in the lateral decubitus position using FASTak 2.8-mm suture anchors (FASTak, Arthrex, Naples, Florida). Treatment outcomes were evaluated using the Rowe and University of California at Los Angeles rating system (UCLA). According to Rowe scores, there were 71 (81.5%) excellent, 12 (12.6%) good, 5 (5.3%) satisfactory, and 2 (2.1%) poor results. Rowe scores improved in a statistically significant manner (p=0.00) post-surgery, to a mean of 90 (range: 25-100). Treatment outcomes measured as UCLA scores improved in a statistically significant manner (p=0.00), reaching post-operative levels of 12-35 (mean: 33.5). There were 9 recurrences, 1 case of axillary nerve praxia, and 1 case of anchor loosening. With rigorous criteria for qualifying patients for surgery, arthroscopic treatment of post-traumatic anterior shoulder instability produces good outcomes and low recurrence and complication rates irrespective of the number of previous dislocations, age, or sex.

  19. Long-term study of anterior cruciate ligament reconstruction for chronic instability using the central one-third patellar tendon and a lateral extraarticular tenodesis.

    PubMed

    Aglietti, P; Buzzi, R; D'Andria, S; Zaccherotti, G

    1992-01-01

    Forty-four patients with symptomatic chronic anterior cruciate ligament instabilities that had been reconstructed with the central one-third patellar tendon and a lateral extraarticular iliotibial band tenodesis were studied at an average followup of 7 years (range, 4 to 10). The cases with associated medial, lateral, or posterior laxity were not included, nor were the cases with more than minimal preoperative degenerative changes. The average age at surgery was 21 years (range, 16 to 33). A postoperative cast was used for 4 weeks. Satisfactory objective stability, which was defined as a KT-1000 side-to-side difference of up to 5 mm at the manual maximum test, was obtained in 37 (84%) of the patients. In 25 patients (57%), stability was restored within normal limits (less than or equal to 3 mm). No deterioration of the KT-1000 stability was noted at two follow-up visits performed by the same examiner (at an average of 4 and 7 years). A return to high-risk sports was possible in 27 (62%) of the patients. Difficulties in regaining a complete range of motion were recorded in 5 (11%) of the patients. A flexion contracture of 5 degrees to 7 degrees was also found in 5 patients. Significant patellofemoral symptoms were present in 4 patients (9%). A 5% to 11% shortening of the patella tendon was observed in 14 (32%) of the knees, but did not correlate with patellar problems. Moderate radiographic changes were noted in eight patients (18%) at followup and correlated with meniscectomy and pain. Overall satisfactory results were obtained in this initial experience in 29 (66%) of the patients.(ABSTRACT TRUNCATED AT 250 WORDS)

  20. Comparative study of open and arthroscopic coracoid transfer for shoulder anterior instability (Latarjet)-clinical results at short term follow-up.

    PubMed

    Kordasiewicz, Bartłomiej; Małachowski, Konrad; Kicinski, Maciej; Chaberek, Sławomir; Pomianowski, Stanisław

    2017-05-01

    The aim of this study was to compare early clinical results after open and arthroscopic Latarjet stabilisation in anterior shoulder instability. Our hypothesis was the results of arthroscopic stabilisation were comparable with the results of open procedure. The clinical results of the patients after primary Latarjet procedure were analysed. Patients operated on between 2006 and 2011 using an open technique composed the OPEN group and patients operated on arthroscopically between 2011 and 2013 composed the ARTHRO group; 48 out of 55 shoulders (87%) in OPEN and 62 out of 64 shoulders (97%) in ARTHRO were available to follow-up. The average age at surgery was 28 years in OPEN and 26 years in ARTHRO. The mean follow-up was 54.2 months in OPEN and 23.4 months in ARTHRO. Intra-operative data were analysed regarding time of surgery, concomitant lesions and complications. Patient results were assessed with Walch-Duplay, Rowe, VAS scores and subjective self-evaluation of satisfaction and shoulder function. Computed tomography scan evaluation was used to assess the graft healing. Average time of surgery was significantly shorter in ARTHRO than OPEN: respectively 110 and 120 minutes. The number of intra-operative complications was six (12.5%) in OPEN and five (8.1%) in ARTHRO. The results were comparable in both groups, with no significant difference between OPEN and ARTHRO group: satisfaction rate - 96.8% and 91.9%, shoulder function - 92.2% and 90%, Walch-Duplay score - 83.9 and 76.7 respecively. A significant difference was reported in Rowe score: 87.8 in OPEN and 78.9 in ARTHRO. Another significant difference was found in the presence of "subjective apprehension"-a term referring to the subjective perception of instability with no signs of instability at clinical examination - 28.7% in OPEN and 50% in ARTHRO. Range of motion in both groups were comparable, however patients in OPEN had significantly lower loss of external rotation in adduction to the side comparing to the

  1. Anterolateral Ligament Expert Group consensus paper on the management of internal rotation and instability of the anterior cruciate ligament - deficient knee.

    PubMed

    Sonnery-Cottet, Bertrand; Daggett, Matthew; Fayard, Jean-Marie; Ferretti, Andrea; Helito, Camilo Partezani; Lind, Martin; Monaco, Edoardo; de Pádua, Vitor Barion Castro; Thaunat, Mathieu; Wilson, Adrian; Zaffagnini, Stefano; Zijl, Jacco; Claes, Steven

    2017-06-01

    Purpose of this paper is to provide an overview of the latest research on the anterolateral ligament (ALL) and present the consensus of the ALL Expert Group on the anatomy, radiographic landmarks, biomechanics, clinical and radiographic diagnosis, lesion classification, surgical technique and clinical outcomes. A consensus on controversial subjects surrounding the ALL and anterolateral knee instability has been established based on the opinion of experts, the latest publications on the subject and an exchange of experiences during the ALL Experts Meeting (November 2015, Lyon, France). The ALL is found deep to the iliotibial band. The femoral origin is just posterior and proximal to the lateral epicondyle; the tibial attachment is 21.6 mm posterior to Gerdy's tubercle and 4-10 mm below the tibial joint line. On a lateral radiographic view the femoral origin is located in the postero-inferior quadrant and the tibial attachment is close to the centre of the proximal tibial plateau. Favourable isometry of an ALL reconstruction is seen when the femoral position is proximal and posterior to the lateral epicondyle, with the ALL being tight upon extension and lax upon flexion. The ALL can be visualised on ultrasound, or on T2-weighted coronal MRI scans with proton density fat-suppressed evaluation. The ALL injury is associated with a Segond fracture, and often occurs in conjunction with acute anterior cruciate ligament (ACL) injury. Recognition and repair of the ALL lesions should be considered to improve the control of rotational stability provided by ACL reconstruction. For high-risk patients, a combined ACL and ALL reconstruction improves rotational control and reduces the rate of re-rupture, without increased postoperative complication rates compared to ACL-only reconstruction. In conclusion this paper provides a contemporary consensus on all studied features of the ALL. The findings warrant future research in order to further test these early observations, with the

  2. Arthroscopic Bankart repair combined with remplissage technique for the treatment of anterior shoulder instability with engaging Hill-Sachs lesion: a report of 49 cases with a minimum 2-year follow-up.

    PubMed

    Zhu, Yi-Ming; Lu, Yi; Zhang, Jin; Shen, Jie-Wei; Jiang, Chun-Yan

    2011-08-01

    Engaging Hill-Sachs lesions are known to be a risk factor for recurrence dislocation after arthroscopic repair in patients with anterior shoulder instability. For a large engaging Hill-Sachs lesion, arthroscopic remplissage is a solution. Arthroscopic Bankart repair combined with the Hill-Sachs remplissage technique can achieve good results without significant impairment of shoulder function. Case Series; Level of evidence, 4. Forty-nine consecutive patients who underwent arthroscopic Bankart repair and Hill-Sachs remplissage for anterior shoulder instability were followed up for a mean duration of 29.0 months (range, 24-35 months). There were 42 males and 7 females with a mean age of 28.4 years (range, 16.7-54.7 years). All patients had diagnosed traumatic unidirectional anterior shoulder instability with a bony lesion of glenoid and an engaging Hill-Sachs lesion. Physical examination, radiographs, and magnetic resonance imaging were performed during postoperative follow-up. The American Shoulder and Elbow Surgeons (ASES) score, Constant score, and Rowe score were used to evaluate shoulder function. The active forward elevation increased a mean of 8.0° (range, -10° to 80°) postoperatively. However, the patients lost 1.9° (range, -40° to 30°) of external rotation to the side. Significant improvement was detected with regard to the ASES score (84.7 vs 96.0, P < .001), Constant score (93.3 vs 97.8, P = .005), and Rowe score (36.8 vs 89.8, P < .001).There were 1 redislocation, 2 subluxations, and 1 patient with a positive apprehension test; the overall failure rate was 8.2% (4 of 49). Successful healing of the infraspinatus tendon within the Hill-Sachs lesion was shown by magnetic resonance imaging. Arthroscopic Bankart repair combined with Hill-Sachs remplissage can restore shoulder stability without significant impairment of shoulder function in patients with engaging Hill-Sachs lesions.

  3. The Sheffield bone block procedure: a new operation for the treatment of glenoid bone loss in patients with anterior traumatic shoulder instability

    PubMed Central

    Storey, Phil; Macinnes, Scott J; Ali, Amjid; Potter, David

    2015-01-01

    Background The purpose of the present study was to evaluate the results of the Sheffield bone block procedure for anteroinferior bone loss in traumatic shoulder instability. In this modified open technique, the medial half of coracoid process without its soft tissue attachments is used to provide congruent augmentation of the anteroinferior glenoid and secured with two screws. Methods In this retrospective consecutive case series (2007–11), all patients having recurrent traumatic instability with glenoid bone loss > 20% and/or a large Hill–Sachs lesion were included. The shoulder function was evaluated clinically and by Oxford Shoulder Instability Score (OSIS; by post/telephone). Results There were 84 patients in this series with a large proportion engaged in contact sports. Mean (range) age was 33 years (16 years to 45 years); male : female, 59 : 8; mean (range) follow-up period was 48 months (36 months to 84 months) and the response rate 89% (75/84). Mean postoperative OSIS was 43 (33 to 46) and one patient had re-dislocation (1.3%). No neurovascular complications/hardware failure/non-union/infections were noted. By 6 months, 85% patients had returned to pre-injury sport and 93% had returned to pre-injury work. Conclusions The Sheffield bone block procedure provides reliable and satisfactory results in patients having recurrent instability with glenoid bone loss and/or a large Hill–Sachs lesion with minimal complications and an excellent chance of returning to original sport and occupation. PMID:27583007

  4. Dual-window subscapularis-sparing approach: a new surgical technique for combined reconstruction of a glenoid bone defect or bankart lesion associated with a HAGL lesion in anterior shoulder instability.

    PubMed

    Bhatia, Deepak N

    2012-03-01

    Combined bankart lesion and humeral avulsion of glenohumeral ligament lesion (HAGL) is a well-described pathologic complex in anterior shoulder instability; open surgical approaches with and without arthroscopic assistance have been suggested for simultaneous 1-stage repair of these lesions. Presence of a significant glenoid bone defect (inverted-pear glenoid) adds to the complexity of the problem and necessitates a bony reconstruction procedure. Open surgical approaches described for management of this combined lesion complex in anterior shoulder instability necessitate a subscapularis-cutting approach; suboptimal healing of the tenotomized subscapularis and subsequent delayed rehabilitation predisposes to late subscapularis dysfunction, and this compromises clinical outcomes. This study describes a new surgical technique that utilizes a dual-window approach through the subscapularis muscle; the dual window enables access to the glenoid and humeral lesions without the need for a subscapularis tenotomy. The approach can be used to perform a congruent-arc Latarjet procedure (for glenoid bone defects) or a Bankart repair (for capsulolabral lesions), in combination with a HAGL repair. Preliminary arthroscopy is essential to identify significant bone defects and HAGL lesions. The dual-window approach for reconstruction of the lesions involves (1) a lateral "subscapularis-sparing" window to identify and repair the HAGL lesion; (2) a medial "subscapularis muscle-splitting" window to perform either a glenoid capsulolabral reconstruction or a congruent-arc Latarjet procedure; and (3) a balanced inferior capsular shift and lateralization procedure of the glenohumeral capsule. Technical tips and guidelines to avoid complications are discussed, and a rehabilitation protocol is presented.

  5. Rim reconstruction with autogenous iliac crest for anterior glenoid deficiency: forty-three instability cases followed for 5-19 years.

    PubMed

    Steffen, Viviane; Hertel, Ralph

    2013-04-01

    The purpose of this study was to evaluate the long-term results of instability patients treated with iliac crest graft glenoid augmentation. Retrospective study including 48 consecutive patients (40 male; mean age 25; range, 17-35). There were 20 primary and 28 revision cases. Three patients declined follow-up examination, and 5 lost to >5 years follow-up. Mean follow-up was 9.2 years (range, 5-19). Reconstruction comprised: iliac crest graft, interposition of the labrum on the burred surface of the graft and capsular re-tensioning. We measured the Oxford Shoulder Instability Score (OSIS) and assessed arthrotic changes and atrophy and fatty infiltration of the subscapularis. 8/43 had residual pain, 3/43 had a subjective sensation of instability, 1/43 had a re-dislocation and required re-intervention. The mean OSIS was 18.1 points (12-50) (n = 40). 1/40 developed postoperative subscapularis insufficiency. The mean subscapularis atrophy was 7.4% (37% atrophy to 27% hypertrophy). 2/40 had a relevant fatty infiltration of the SSC muscle stage III to stage IV. 19/40 had mild and 1/40 had a moderate arthrosis. Arthrosis progressed by 1 stage in 7 of 35 shoulders. The mean residual glenoid defect area was 4.0% (0-13.5) and the mean defect width was 8.3% (range, 0-19.2) (n = 40). Glenoid rim reconstruction with iliac crest graft was equally effective for patients with primary repair and for failed previous stabilization. It offered the advantage of an anatomic reconstruction with a comparatively good long-term preservation of the joint line. Copyright © 2013 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Mosby, Inc. All rights reserved.

  6. Infraspinatus strength assessment and ultrasound evaluation of posterior capsulotenodesis after arthroscopic hill-sachs remplissage in traumatic anterior glenohumeral instability: a retrospective controlled study protocol.

    PubMed

    Merolla, Giovanni; Porcellini, Giuseppe

    2014-04-01

    Giovanni Merolla Co-investigator: Giuseppe Porcellini Investigation performed at the Biomechanics Laboratory "Marco Simoncelli", D. Cervesi Hospital, Cattolica - Italy PLAN OF CLINICAL INVESTIGATION (PCI): Version 1.0 of June 12, 2012 Approved by AV/IRST Ethical Committee (Comitato Etico Area Vasta Romagna) and authorized by AUSL RN ("Determina AUSL Rimini numero 326 del 29/03/2013: Remplissage U.O Chirurgia della Spalla - Valutazione clinica ed ultrasonografica dell'infraspinato dopo capsulo-tenodesi artroscopica (remplissage) nell'instabilità anteriore traumatica di spalla con lesione di Bankart e difetto omerale di Hill-Sachs").

  7. RESULTS FROM LATARJET SURGERY FOR TREATING TRAUMATIC ANTERIOR SHOULDER INSTABILITY ASSOCIATED WITH BONE EROSION IN THE GLENOID CAVITY, AFTER MINIMUM FOLLOW-UP OF ONE YEAR

    PubMed Central

    Ikemoto, Roberto Yukio; Murachovisky, Joel; Nascimento, Luis Gustavo Prata; Bueno, Rogério Serpone; Almeida, Luiz Henrique Oliveira; Strose, Eric; Helmer, Fábio Fernando

    2015-01-01

    Objective: Evaluate the results from the Latarjet procedure in patients with anterior recurrent dislocation of the shoulder who present bone loss of the glenoid cavity greater than 25%. Methods: Twenty six male patients underwent the Latarjet procedure, The bone loss was evaluated by means of radiography using the Bernageau view and by means of CAT scan. The patients were evaluated with regard to range of motion, using the Rowe and UCLA scales, before and after the operation, and by radiographs to assess the presence of arthrosis, position and consolidation of the graft and positioning of the screws. Statistical analysis was used to assess whether there was any relationship between the number of episodes of dislocation and the presence of arthrosis, , and any relationship between arthrosis and limitations on lateral rotation. Differences in range of motion between the operated and unaffected sides and in the UCLA and Rowe scale. Results: The means for elevation and lateral rotation were statistically poorer on the operated side. The UCLA and Rowe scale showed that there was a statistically significant improvement in the clinical-functional results (P < 0.001 for both). There was a relationship between the number of episodes of dislocation and the presence of arthrosis, We also did not observe any correlation between limitations on lateral rotation and arthrosis. Conclusion: The Latarjet procedure is an efficient method for cases of severe erosion of the glenoid margin. PMID:27027053

  8. A systematic review and meta-analysis of clinical and patient-reported outcomes following two procedures for recurrent traumatic anterior instability of the shoulder: Latarjet procedure vs. Bankart repair.

    PubMed

    An, Vincent Vinh Gia; Sivakumar, Brahman Shankar; Phan, Kevin; Trantalis, John

    2016-05-01

    The Bankart repair and Latarjet procedure are both viable surgical options for recurrent traumatic anterior instability of the shoulder joint. The anatomic repair is the more popular option, with 90% of surgeons internationally choosing the Bankart repair as the initial treatment. There has been no previous review directly comparing the 2 techniques. Hence, we aimed to systematically review studies to compare the outcomes of Bankart repairs vs. the Latarjet procedure for recurrent instability of the shoulder. Six electronic databases were searched for original, English-language studies comparing the Bankart and Latarjet procedures. Studies were critically appraised using the Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) checklist. Data were extracted from the text, tables, and figures of the selected studies. Eight comparative studies were identified with 795 shoulders; 416 of them underwent open or arthroscopic Bankart repairs, and 379 were repaired by the open Latarjet procedure. Primary and revision procedures were studied. The Latarjet procedure conferred significantly lower risk of recurrence and redislocation. There was no significant difference in the rates of complication requiring reoperation between the two procedures. Rowe scores were higher and loss of external rotation lower in the Latarjet group compared with the Bankart repair group. Our studies demonstrate that the Latarjet procedure is a viable and possibly superior alternative to the Bankart repair, offering greater stability with no significant increase in complication rate. However, the studies identified were retrospective and of limited quality, and therefore randomized controlled trials with large populations of patients or prospective assessment of national orthopedic registries should be employed to confirm our findings. Copyright © 2016 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Elsevier Inc. All rights reserved.

  9. Chronic ankle instability: Current perspectives

    PubMed Central

    Al-Mohrej, Omar A.; Al-Kenani, Nader S.

    2016-01-01

    Ankle sprain is reported to be among the most common recurrent injuries. About 20% of acute ankle sprain patients develop chronic ankle instability. The failure of functional rehabilitation after acute ankle sprain leads to the development of chronic ankle instability. Differentiation between functional and anatomical ankle instability is very essential to guide the proper treatment. Stability testing by varus stress test and anterior drawer test should be carried out. Subtalar instability is an important pathology that is commonly by passed during the assessment of chronic ankle instability. Unlike acute ankle sprain, chronic ankle instability might require surgical intervention. The surgical and conservative management options can be very much developed by in-depth knowledge of the ankle anatomy, biomechanics, and pathology. Anatomical repair, augmentation by tendon, or both are the basic methods of surgical intervention. Arthroscopy is becoming more popular in the management of chronic ankle instability. PMID:27843798

  10. Anterior-inferior tibiofibular ligament anatomical repair and augmentation versus trans-syndesmosis screw fixation for the syndesmotic instability in external-rotation type ankle fracture with posterior malleolus involvement: A prospective and comparative study.

    PubMed

    Zhan, Yu; Yan, Xiaoyu; Xia, Ronggang; Cheng, Tao; Luo, Congfeng

    2016-07-01

    Syndesmosis injury is common in external-rotation type ankle fractures (ERAF). Trans-syndesmosis screw fixation, the gold-standard treatment, is currently controversial for its complications and biomechanical disadvantages. The purpose of this study was to introduce a new method of anatomically repairing the anterior-inferior tibiofibular ligament (AITFL) and augmentation with anchor rope system to treat the syndesmotic instability in ERAF with posterior malleolus involvement and to compare its clinical outcomes with that of trans-syndesmosis screw fixation. 53 ERAFs with posterior malleolus involvement received surgery, and the syndesmosis was still unstable after fracture fixation. They were randomised into screw fixation group and AITFL anatomical repair with augmentation group. Reduction quality, syndesmosis diastasis recurrence, pain (VAS score), time back to work, Olerud-Molander ankle score and range of motion (ROM) of ankle were investigated. Olerud-Molander score in AITFL repair group and screw group was 90.4 and 85.8 at 12-month follow-up (P>0.05). Plantar flexion was 31.2° and 34.3° in repair and screw groups (P=0.04). Mal-reduction happened in 5 cases (19.2%) in screw group while 2 cases (7.4%) in repair group. Postoperative syndesmosis re-diastasis occurred in 3 cases in screw group while zero in repair group (P>0.05). Pain score was similar between the two groups (P>0.05). Overall complication rate and back to work time were 26.9% and 3.7% (P=0.04), 7.15 months and 5.26 months (P=0.02) in screw group and repair group, respectively. For syndesmotic instability in ERAF with posterior malleolus involvement, the method of AITFL anatomical repair and augmentation with anchor rope system had an equivalent functional outcome and reduction, earlier rehabilitation and less complication compared with screw fixation. It can be selected as an alternative. Copyright © 2016 Elsevier Ltd. All rights reserved.

  11. History and Physical Examination for Shoulder Instability.

    PubMed

    Haley, Col Chad A

    2017-09-01

    Glenohumeral instability frequently occurs in young active individuals especially those engaged in athletic and military activities. With advanced imaging and arthroscopic evaluation, our understanding of the injury patterns associated with instability has significantly improved. The majority of instability results from a traumatic anterior event which presents with common findings in the history, examination, and imaging studies. As such, a comprehensive evaluation of the patient is important to correctly diagnose the instability patterns and thus provide appropriate treatment intervention. With the correct diagnosis and improved surgical techniques, the majority of patients with instability can return to preinjury levels.

  12. Magnetic resonance imaging in glenohumeral instability

    PubMed Central

    Jana, Manisha; Gamanagatti, Shivanand

    2011-01-01

    The glenohumeral joint is the most commonly dislocated joint of the body and anterior instability is the most common type of shoulder instability. Magnetic resonance (MR) imaging, and more recently, MR arthrography, have become the essential investigation modalities of glenohumeral instability, especially for pre-procedure evaluation before arthroscopic surgery. Injuries associated with glenohumeral instability are variable, and can involve the bones, the labor-ligamentous components, or the rotator cuff. Anterior instability is associated with injuries of the anterior labrum and the anterior band of the inferior glenohumeral ligament, in the form of Bankart lesion and its variants; whereas posterior instability is associated with reverse Bankart and reverse Hill-Sachs lesion. Multidirectional instability often has no labral pathology on imaging but shows specific osseous changes such as increased chondrolabral retroversion. This article reviews the relevant anatomy in brief, the MR imaging technique and the arthrographic technique, and describes the MR findings in each type of instability as well as common imaging pitfalls. PMID:22007285

  13. Posterior Shoulder Instability.

    PubMed

    Brelin, Alaina; Dickens, Jonathan F

    2017-09-01

    Posterior shoulder instability is a relatively uncommon condition, occurring in ∼10% of those with shoulder instability. Because of the rarity of the condition and the lack of knowledge in treatment, it is often misdiagnosed or patients experience a delay in diagnosis. Posterior instability typically affects athletes participating in contact or overhead sports and is usually the result of repetitive microtrauma or blunt force with the shoulder in the provocative position of flexion, adduction, and internal rotation, leading to recurrent subluxation events. Acute traumatic posterior dislocations are rare injuries with an incidence rate of 1.1 per 100,000 person years. This rate is ∼20 times lower than that of anterior shoulder dislocations. Risk factors for recurrent instability are: (1) age below 40 at time of first instability; (2) dislocation during a seizure; (3) a large reverse Hill-Sachs lesion; and (4) glenoid retroversion. A firm understanding of the pathoanatomy, along with pertinent clinical and diagnostic modalities is required to accurately diagnosis and manage this condition.

  14. Muscle activation patterns in patients with recurrent shoulder instability

    PubMed Central

    Jaggi, Anju; Noorani, Ali; Malone, Alex; Cowan, Joseph; Lambert, Simon; Bayley, Ian

    2012-01-01

    Purpose: The aim of this study is to present muscle patterns observed with the direction of instability in a series of patients presenting with recurrent shoulder instability. Materials and Methods: A retrospective review was carried out on shoulder instability cases referred for fine wire dynamic electromyography (DEMG) studies at a specialist upper limb centre between 1981 and 2003. An experienced consultant clinical neurophysiologist performed dual needle insertion into four muscles (pectoralis major (PM), latissimus dorsi (LD), anterior deltoid (AD) and infraspinatus (IS)) in shoulders that were suspected to have increased or suppressed activation of muscles that could be contributing to the instability. Raw EMG signals were obtained while subjects performed simple uniplanar movements of the shoulder. The presence or absence of muscle activation was noted and compared to clinical diagnosis and direction of instability. Results: A total of 140 (26.6%) shoulders were referred for fine wire EMG, and 131 studies were completed. Of the shoulders tested, 122 shoulders (93%) were identified as having abnormal patterns and nine had normal patterns. PM was found to be more active in 60% of shoulders presenting with anterior instability. LD was found to be more active in 81% of shoulders with anterior instability and 80% with posterior instability. AD was found to be more active in 22% of shoulders with anterior instability and 18% with posterior instability. IS was found to be inappropriately inactive in only 3% of shoulders with anterior instability but in 25% with posterior instability. Clinical assessment identified 93% of cases suspected to have muscle patterning, but the specificity of the clinical assessment was only correct in 11% of cases. Conclusion: The DEMG results suggest that increased activation of LD may play a role in both anterior and posterior shoulder instability; increased activation of PM may play a role in anterior instability. PMID:23493512

  15. Spectrum of magnetic resonance imaging findings in clinical glenohumeral instability

    PubMed Central

    Jana, Manisha; Srivastava, Deep Narayan; Sharma, Raju; Gamanagatti, Shivanand; Nag, Hiralal; Mittal, Ravi; Upadhyay, Ashish Dutt

    2011-01-01

    The glenohumeral joint is the most commonly dislocated joint in the body, and anterior instability is the most common type of shoulder instability. Depending on the etiology and the age of the patient, there may be associated injuries, for example, to the anterior-inferior labro-ligamentous structures (in young individuals with traumatic instability) or to the bony components (commoner in the elderly), which are best visualized using MRI and MR arthrography. Anterior instability is associated with a Bankart lesion and its variants and abnormalities of the anterior band of the inferior glenohumeral ligament (IGHL), whereas posterior instability is associated with reverse Bankart and reverse Hill-Sachs lesions. Cases of multidirectional instability often have no labral pathology on imaging but show specific osseous changes including increased chondrolabral retroversion. This article reviews the relevant anatomy in brief and describes the MRI findings in each type, with the imaging features of the common abnormalities. PMID:21799591

  16. Collective instabilities

    SciTech Connect

    K.Y. Ng

    2003-08-25

    The lecture covers mainly Sections 2.VIII and 3.VII of the book ''Accelerator Physics'' by S.Y. Lee, plus mode-coupling instabilities and chromaticity-driven head-tail instability. Besides giving more detailed derivation of many equations, simple interpretations of many collective instabilities are included with the intention that the phenomena can be understood more easily without going into too much mathematics. The notations of Lee's book as well as the e{sup jwt} convention are followed.

  17. [Intervertebral instability].

    PubMed

    Colaiacomo, M C; Tortora, A; Di Biasi, C; Polettini, E; Casciani, E; Gualdi, G F

    2009-01-01

    The clinic diagnosis of degenerative lumbar intervertebral instability is a controversial topic and have not yet been clarified clinical criteria for to define this condition with accuracy. Although the lumbar pain is the most common symptom in patients who have lumbar intervertebral instability its clinical presentation is not specific; moreover in patients with lumbar pain there are no agreed signs and symptoms that can be truly attributable to instability. Despite better imaging techniques of testing spinal instability there is not a clear relations between radiologic signs of instability and clinical symptoms. It is, however, still far from unanimous definition of degenerative lumbar intervertebral instability accepted from all specialists involved in diagnosis and treatment of this condition; however, seem there is most agree about suspected vertebral instability. Nevertheless this unresolved topic, it is possible to state that imaging play an increasing role in diagnosis and management of patients with suspected instability. The aim of this study is to investigate the different imaging modalities most indicated in diagnosis if vertebral instability and whether degenerative change can be associated with lower back pain.

  18. An Evaluation of the Clinical and Anatomic Predictors of Outcomes at a Minimum of 2 yrs Following the Latarjet Procedure for Recurrent Anterior Shoulder Instability with Glenoid Bone Loss

    PubMed Central

    Mook, William R.; Petri, Maximilian; Greenspoon, Joshua A.; Horan, Marilee P.; Millett, Peter J.

    2015-01-01

    Objectives: Although the Latarjet procedure for the treatment of recurrent shoulder instability is highly successful, reasons for failure are often unclear. The purpose of our study was to evaluate clinical and anatomic characteristics that were predictive of continued instability or poor outcomes following the Latarjet procedure. Methods: In this IRB approved study, patients who underwent open coracoid Latarjet procedures for anteroinferior instability with glenoid bone loss (>20%) prior to October of 2012 were included. Anatomic measurements of coracoid size (anteroposterior surface area, maximal coracoid width), conjoint and subscapularis tendon widths, estimated glenoid defect surface area, Hill-Sach's Interval, and projected postoperative glenoid track engagement were obtained from preoperative cross-sectional imaging. When the projected glenoid track was smaller than the Hill-Sach's interval, the lesion was determined to be outside-&-engaged compared to inside-&-non-engaged. Patient reported subjective data that was prospectively collected and retrospectively reviewed included patient satisfaction, instability events, SANE score, ASES score, DASH score, and SF-12 PCS. Patients that progressed to another shoulder surgery not related to instability were considered complications and patients that continued to experience dislocations or who underwent revision instability surgeries were considered failures. Results: Thirty-nine shoulders in 39 patients (34 men, 5 women) with a mean age of 26 (range 16-43) were included at a mean follow-up was 3.3 years (2- 7.9 years). There were 25 out of 39 that had prior stabilization surgery and 6 workman's compensation claims. One patient was revised due to broken hardware at 2 months and one because of coracoid nonunion at 18 months. One patient experienced postsurgical adhesive capsulitis treated surgically at a year. All subjective outcome scores significantly improved (p<.05) and a 9 out of 10 median satisfaction score was

  19. Bilateral agenesis of the anterior cruciate ligament: MRI evaluation.

    PubMed

    Bedoya, Maria A; McGraw, Michael H; Wells, Lawrence; Jaramillo, Diego

    2014-09-01

    Bilateral agenesis of the anterior cruciate ligament (ACL) is extremely rare. We describe a 13-year-old girl who presented with bilateral knee pain without history of trauma; she has two family members with knee instability. Magnetic resonance imaging showed bilateral absence of the ACL, and medial posterior horn meniscal tears. Bilateral arthroscopic partial meniscectomy and anterior cruciate ligament reconstruction was performed.

  20. History of shoulder instability surgery.

    PubMed

    Randelli, Pietro; Cucchi, Davide; Butt, Usman

    2016-02-01

    The surgical management of shoulder instability is an expanding and increasingly complex area of study within orthopaedics. This article describes the history and evolution of shoulder instability surgery, examining the development of its key principles, the currently accepted concepts and available surgical interventions. A comprehensive review of the available literature was performed using PubMed. The reference lists of reviewed articles were also scrutinised to ensure relevant information was included. The various types of shoulder instability including anterior, posterior and multidirectional instability are discussed, focussing on the history of surgical management of these topics, the current concepts and the results of available surgical interventions. The last century has seen important advancements in the understanding and treatment of shoulder instability. The transition from open to arthroscopic surgery has allowed the discovery of previously unrecognised pathologic entities and facilitated techniques to treat these. Nevertheless, open surgery still produces comparable results in the treatment of many instability-related conditions and is often required in complex or revision cases, particularly in the presence of bone loss. More high-quality research is required to better understand and characterise this spectrum of conditions so that successful evidence-based management algorithms can be developed. IV.

  1. Hybrid rocket instability

    NASA Technical Reports Server (NTRS)

    Greiner, B.; Frederick, R. A., Jr.

    1993-01-01

    The paper provides a brief review of theoretical and experimental studies concerned with hybrid rocket instability. The instabilities discussed include atomization and mixing instabilities, chuffing instabilities, pressure coupled combustion instabilities, and vortex shedding. It is emphasized that the future use of hybrid motor systems as viable design alternatives will depend on a better understanding of hybrid instability.

  2. Magnetohydrodynamic instability

    NASA Technical Reports Server (NTRS)

    Priest, E. R.; Cargill, P.; Forbes, T. G.; Hood, A. W.; Steinolfson, R. S.

    1986-01-01

    There have been major advances in the theory of magnetic reconnection and of magnetic instability, with important implications for the observations, as follows: (1) Fast and slow magnetic shock waves are produced by the magnetohydrodynamics of reconnection and are potential particle accelerators. (2) The impulsive bursty regime of reconnection gives a rapid release of magnetic energy in a series of bursts. (3) The radiative tearing mode creates cool filamentary structures in the reconnection process. (4) The stability analyses imply that an arcade can become unstable when either its height or twist of plasma pressure become too great.

  3. [Anterior cruciate ligament injuries in children].

    PubMed

    Tercier, S; Zambelli, P-Y

    2013-07-17

    An increasing number of anterior cruciate ligament injuries are now seen in children and girls seem to be equally affected. Such neglected or untreated lesions could be the cause of early degenerative changes. Recently, many authors support the trend toward early surgical management in skeletally immature patients with complex meniscal tear or recurrent knee instability after proper rehabilitation. Improvement in pediatric knowledge and surgical techniques tend to support a tendency for more surgical treatment in children. The type of management is choosing according to history and physical examination. Magnetic resonance imaging is a useful tool not only for diagnosis but also for surgical treatment planning. We usually recommend anterior cruciate ligament reconstruction in children with knee instability or with further damages to the joint.

  4. Recurrent Shoulder Instability After Primary Bankart Repair.

    PubMed

    Donohue, Michael A; Mauntel, Timothy C; Dickens, Jonathan F

    2017-09-01

    The glenohumeral joint is one of the most frequently dislocated joints and occurs with increasing frequency in collision and contact athletes, especially those in sports that repeatedly place the glenohumeral joint in a position of vulnerability. Nonoperative management of shoulder instability especially in young contact athletes results in unacceptably high recurrence rates; thus, early surgical stabilization has become commonplace. Surgical stabilization typically yields acceptable outcomes. However, recurrent anterior instability may occur following a previous stabilization procedure at rates of 7% to 12%. Recurrent glenohumeral instability represents a treatment challenge for orthopedic surgeons as it not only has the potential to result in subsequent surgery, therapy, and missed activity time, but also has been associated with long-term degenerative joint changes. Thus, recurrent instability requires close examination to determine underlying pathology leading to failure. Evaluation of underlying pathology requires consideration of patient activity-related factors, hyperlaxity and multidirectional instability, glenoid bone loss, glenoid track lesions, and other pathologic lesions. Revision surgical stabilization approaches include arthroscopic and open stabilization, as well as glenoid osseous augmentation procedures. Postoperative rehabilitation and release to sports and activity must be tailored to protect the shoulder from continued instability. Understanding that risk of recurrent glenohumeral instability and the risk factors associated with it are essential so that these factors may be mitigated and recurrent instability prevented.

  5. Predictors for Surgery in Shoulder Instability

    PubMed Central

    Lebus, George F.; Raynor, Martin B.; Nwosu, Samuel K.; Wagstrom, Emily; Jani, Sunil S.; Carey, James L.; Hettrich, Carolyn M.; Cox, Charles L.; Kuhn, John E.

    2015-01-01

    Background: Shoulder instability is a common cause of pain and dysfunction in young, active patients. While studies have analyzed risk factors for recurrent instability and failure after instability surgery, few have examined which variables are associated with initial surgery in this patient population. Purpose: To identify variables that may be associated with surgical intervention in patients with shoulder instability in the context of the FEDS (frequency, etiology, direction, severity) classification, a system that may be useful in the surgical treatment of shoulder instability patients. Study Design: Cohort study (prognosis); Level of evidence, 2. Methods: A database of patients treated for shoulder instability from 3 separate institutions from 2005 to 2010 was generated using International Classification of Diseases–9th Revision data. Data were collected via retrospective review. Injury data were categorized according to the FEDS system. Data were analyzed for significance, with the primary outcome of surgical intervention. Summary statistics were used to assess which variables were associated with eventual surgery. To test the unadjusted bivariate associations between shoulder surgery and each data point, Pearson chi-square tests were used for categorical variables and Wilcoxon tests were used for continuous variables. Results: Over the study time period, 377 patients were treated for shoulder instability. Patients who had surgery were more likely younger, had recurrent instability, and had their initial injury while playing a sport. Most patients had anterior instability; however, there was a greater proportion of posterior instability patients in the operative group. Severity of dislocation, measured by whether the patient required help to relocate the shoulder, was not significantly associated with eventual surgery. While imaging was not available for all patients, surgical patients were more likely to have magnetic resonance imaging findings of

  6. Lemaire extraarticular plasty in anterolateral knee instability

    PubMed Central

    Paús, Vicente; Graieb, Ariel; Torrengo, Federico

    2017-01-01

    Anterolateral instability of the knee results from injury to the lateral capsular complex and the anterior cruciate ligament (ACL), and it should not be considered an isolated injury. Over the past years these structures have received renewed interest. The anterolateral ligament (ALL) recently described extends from the lateral side of the lateral femoral condyle to the antero-lateral edge of the tibia, and it is supposed to play a major role in anterolateral stability. ACL extra-articular tenodesis, initially developed as a single procedure, is now complementary to intra-articular plasty. Our indications are: pure rotational instability, symptomatic instability in non-athletes, and revision surgery. Lemaire-type plasty and post-opeartive care are described in detail. We suggest thorough patient history and clinical examination prior to surgical decision. Lemaire-type plasty effectively controls anterolateral instability.

  7. Rodeo athletes: management of shoulder instability.

    PubMed

    Figueiredo, Eduardo A; Belangero, Paulo S; Cohen, Carina; Louchard, Rafael L; Terra, Bernardo B; Pochini, Alberto C; Andreoli, Carlos V; Cohen, Moisés; Ejnisman, Benno

    2016-05-01

    The aim of this study was to describe epidemiological data and evaluate the clinical results of traumatic anterior glenohumeral instability in rodeo athletes. Thirteen patients, all male, with a mean age of 23.2 (18-31) years old, with anterior glenohumeral instability were include in this study. In 9 patients, the right side was affected. The mean time elapsed between injury and undergoing surgery was 56 months (24-120 months). The surgical technique used (arthroscopic or open bone block procedure) was chosen based on the ISIS (Instability Severity Index Score). Only professional athletes who had been in the sport for at least 60 months were included. Functional evaluation was conducted using the UCLA scale, after a 24-month follow-up period. The number of dislocation episodes varied from 10 to 100 (mean 27 episodes). All of the patients were submitted a surgical treatment open bone block procedure, due to their degree of sport participation, type of sport (forced overhead and collision) and the presence of associated bone defect lesions. According to UCLA criteria, the results were excellent in 12 patients and good in one. The mean time elapsed before returning to the sport was five months, varying between two and ten months. Complications included one patient developing axillary neuropraxia, which was completely resolved six months after the operation, and another patient developed a superficial skin infection. The rodeo athletes with anterior shoulder instability had serious associated bony lesions and has good outcome after bone block procedure.

  8. Polygonal instabilities

    NASA Astrophysics Data System (ADS)

    Labousse, Matthieu

    2015-11-01

    The interaction of a vortex with a free surface is encountered in a series of experiments, the hydraulic jump, the hydraulic bump, the toroidal Leidenfrost experiment. All these experiments share in common an unstable configuration in which azimuthal perturbations give rise to polygonal patterns. We propose a unified theoretical framework to model the emergence of this instability by investigating the stability of a liquid torus with a poloidal motion. As simple as it is, we show that the model retains the necessary ingredients to account for the experimental observations. In this talk, I will first describe the model and compare it to the existing data. However this model is purely inviscid and reaches its limits when being applied to relatively moderate Reynolds flows. So in a second part, I will present a recent experimental and theoretical investigation in which polygonal patterns are now driven by Marangoni flows. To our great surprise, it extends the range of validity of the initial proposed framework, much more than initially expected.

  9. MRI of anterior knee pain.

    PubMed

    Samim, Mohammad; Smitaman, Edward; Lawrence, David; Moukaddam, Hicham

    2014-07-01

    Anterior knee pain is the most common knee complaint. It may be due to a variety of soft tissue or osseous abnormalities. Knowledge of the radiologic appearance of the abnormalities allows more accurate diagnosis of the cause of the pain including chondral abnormalities, patellar instability and dislocation, femoral trochlear dysplasia, abnormal patellar location, bipartite patella, various tendinopathies, bursal inflammation, traction apophysitis in pediatric and adolescent patients, and miscellaneous diseases including mediopatellar plica syndrome and Hoffa's disease. Radiographs are often obtained to exclude acute osseous abnormalities, such as fractures. Magnetic resonance (MR) imaging offers superior soft tissue contrast resolution and allows for more accurate evaluation of the underlying etiology and therefore may improve treatment and possible surgical planning.

  10. Inferior capsular shift operation for multidirectional instability of the shoulder in players of contact sports

    PubMed Central

    Choi, C; Ogilvie-Harris, D

    2002-01-01

    Objectives: To assess the results of inferior capsular shift for multidirectional instability of the shoulder in athletes. Methods: Multidirectional instability was surgically corrected in 53 shoulders in 47 athletes who engaged in contact sports. A history of major trauma was found in eight patients, the others having had minor episodes. Before surgery, all patients had complex combinations of instabilities. The surgical approach was selected according to the predominant direction of instability. Results: Anterior inferior capsular shift was carried out in 37 shoulders, and anterior dislocation recurred in three. In one of these, it was anterior alone, one was anterior and inferior, and one was unstable in all three directions. After posterior inferior capsular shift in 16 shoulders, one dislocation occurred anteriorly and one posteriorly. With the anterior approach, four athletes could not return to sport. Two patients treated with the posterior approach could not return to sport. Of these six failures, five patients had had bilateral repairs. Successful repair based on the criteria of the American Shoulder and Elbow Association was achieved in 92% of anterior repairs and 81% of posterior repairs. Successful return to sport was noted in 82% of patients with anterior repairs, 75% with posterior repairs, and 17% with bilateral repairs. Overall, there were five subsequent dislocations, three in the anterior repair group (8%), and two in the posterior repair group (12%). Conclusions: Inferior capsular shift can successfully correct multidirectional instability in most players of contact sports, but the results in bilateral cases are poor. PMID:12145120

  11. Return to Play Following Anterior Shoulder Dislocation and Stabilization Surgery.

    PubMed

    Donohue, Michael A; Owens, Brett D; Dickens, Jonathan F

    2016-10-01

    Anterior shoulder instability in athletes may lead to time lost from participation and decreases in level of play. Contact, collision, and overhead athletes are at a higher risk than others. Athletes may successfully be returned to play but operative stabilization should be considered for long-term treatment of recurrent instability. Open and arthroscopic stabilization procedures for athletes with less than 20% to 25% bone loss improve return to play rates and decrease recurrent instability, with a slightly lower recurrence with open stabilization. For athletes with greater than 20% to 25% bone loss, an open osseous augmentation procedure should be considered. Published by Elsevier Inc.

  12. Bilateral Anterior Shoulder Dislocation

    PubMed Central

    Siu, Yuk Chuen; Lui, Tun Hing

    2014-01-01

    Introduction: Unilateral anterior shoulder dislocation is one of the most common problems encountered in orthopedic practice. However, simultaneous bilateral anterior dislocation of the shoulders is quite rare. Case Presentation: We report a case of a 75-year-old woman presented with simultaneous bilateral anterior shoulder dislocation following a trauma, complicated with a traction injury to the posterior cord of the brachial plexus. Conclusions: Bilateral anterior shoulder dislocation is very rare. The excessive traction force during closed reduction may lead to nerve palsy. Clear documentation of neurovascular status and adequate imaging before and after a reduction should be performed. PMID:25685749

  13. Giant anterior cervical osteophyte leading to Dysphagia.

    PubMed

    Hwang, Jin Seop; Chough, Chung Kee; Joo, Won Il

    2013-09-01

    Large anterior cervical osteophytes can occur in degeneration of the cervical spine or in diffuse idiopathic skeletal hyperostosis(DISH). Large osteophytes can produce otolaryngological symptoms such as dysphagia, dysphonia, and foreign body sensation. We describe a DISH patient with giant anterior cervical osteophyte causing chronic dysphagia and dysphonia. A 56-year-old man presented with increasing dysphagia, dysphonia, neck pain and neck stiffness. Physical examination of the neck showed a non-tender and hard mass on the left side at the level of C4-5. Radiography showed extensive ossification of anterior longitudinal ligament along the left anterolateral aspect of vertebral bodies from C2 to T1. The ossification was espe cially prominent at the level of C4-5 and linear breakage was noted at same level. Esophagogram revealed a filling defect along the pharynx and lateral displacement of the esophagus. Giant anterior cervical osteophyte was removed through the leftsided anterolateral cervical approach to the spine. Anterior cervical interbody fusion at C4-5 was followed by posterior cervical fixation using lateral mass screws from C3 to C6. After surgery, dysphagia and dysphonia improved immediately. One year later, cervical CT showed bone fusion at C4-5 bodies and no recurrence of osteophyte. DISH is a common cause of anterior cervical osteophyte leading to progressive dysphagia. Keeping this clinical entity in the differential diagnosis is important in patients with progressive neck stiffness, dysphagia or dysphonia. And surgical treatment of symptomatic anterior cervical osteophyte due to DISH should be considered with a solid fusion procedure preventing postoperative instability or osteophyte progress.

  14. Meniscectomy of horizontal tears of the lateral meniscus anterior horn using the joystick technique.

    PubMed

    Park, Ill Ho; Kim, Sung Jae; Choi, Duck Hyun; Lee, Su Chan; Park, Ha Young; Jung, Kwang Am

    2014-01-01

    Unstable inferior leaves of the anterior horn in horizontal tears of the lateral meniscus are challenging lesions for most orthopedic surgeons due to the poor viewing angle and the instability of these lesions. Resection of an exact volume is required for the successful treatment of horizontal tears in the lateral meniscus anterior horn. We report a method based on the joystick technique.

  15. Electron heat flux instability

    NASA Astrophysics Data System (ADS)

    Saeed, Sundas; Sarfraz, M.; Yoon, P. H.; Lazar, M.; Qureshi, M. N. S.

    2017-02-01

    The heat flux instability is an electromagnetic mode excited by a relative drift between the protons and two-component core-halo electrons. The most prominent application may be in association with the solar wind where drifting electron velocity distributions are observed. The heat flux instability is somewhat analogous to the electrostatic Buneman or ion-acoustic instability driven by the net drift between the protons and bulk electrons, except that the heat flux instability operates in magnetized plasmas and possesses transverse electromagnetic polarization. The heat flux instability is also distinct from the electrostatic counterpart in that it requires two electron species with relative drifts with each other. In the literature, the heat flux instability is often called the 'whistler' heat flux instability, but it is actually polarized in the opposite sense to the whistler wave. This paper elucidates all of these fundamental plasma physical properties associated with the heat flux instability starting from a simple model, and gradually building up more complexity towards a solar wind-like distribution functions. It is found that the essential properties of the instability are already present in the cold counter-streaming electron model, and that the instability is absent if the protons are ignored. These instability characteristics are highly reminiscent of the electron firehose instability driven by excessive parallel temperature anisotropy, propagating in parallel direction with respect to the ambient magnetic field, except that the free energy source for the heat flux instability resides in the effective parallel pressure provided by the counter-streaming electrons.

  16. Kinesics of Affective Instability.

    ERIC Educational Resources Information Center

    Dil, Nasim

    1979-01-01

    Discusses the rationale of studying kinesics of affective instability, describes the phenonmenon of affective instability, examines the role of kinesics in the overall process of communication, and presents three case studies. (Author/AM)

  17. Turbine instabilities: Case histories

    NASA Technical Reports Server (NTRS)

    Laws, C. W.

    1985-01-01

    Several possible causes of turbine rotor instability are discussed and the related design features of a wide range of turbomachinery types and sizes are considered. The instrumentation options available for detecting rotor instability and assessing its severity are also discussed.

  18. Anterior cruciate ligament (ACL) injury

    MedlinePlus

    Cruciate ligament injury - anterior; ACL injury; Knee injury - anterior cruciate ligament (ACL) ... knee. It prevents the knee from bending out. Anterior cruciate ligament (ACL) is in the middle of the knee. ...

  19. Anterior Cruciate Ligament (ACL) Injuries

    MedlinePlus

    ... Week of Healthy Breakfasts Shyness Anterior Cruciate Ligament (ACL) Injuries KidsHealth > For Teens > Anterior Cruciate Ligament (ACL) ... and Recovery Coping With an ACL Injury About ACL Injuries A torn anterior cruciate ligament (ACL) is ...

  20. [Anterior tarsal tunnel syndrome].

    PubMed

    Miliam, Palle B; Basse, Peter N

    2009-03-30

    Anterior tarsal tunnel syndrome is a rare entrapment neuropathy of the deep peroneal nerve beneath the extensor retinaculum of the ankle. It may be rare because it is underrecognized clinically.We present a case regarding a 29-year-old man, drummer, who for one and a half year experienced clinical symptoms of anterior tarsal tunnel syndrome. A surgical decompression of the anterior tarsal tunnel was performed, and at the check three months later the symptoms where gone. One year after, there were still no symptoms.

  1. [Isolated anterior cervical hypertrichosis].

    PubMed

    Monteagudo, B; Cabanillas, M; de las Heras, C; Cacharrón, J M

    2009-01-01

    Anterior cervical hypertrichosis was described by Trattner and coworkers in 1991. It consists of a of hair at the anterior cervical level just above the laryngeal prominence. To date, only 28 cases of anterior cervical hypertrichosis have been reported. Although it is normally an isolated finding, it may be associated with mental retardation, hallux valgus, retinal disorders, other hair disorders, facial dysmorphism, or sensory and motor peripheral neuropathy. We report the case of a 27-year-old woman who presented with this condition as an isolated finding.

  2. Revision Anterior Cruciate Ligament Reconstruction

    PubMed Central

    Wilde, Jeffrey; Bedi, Asheesh; Altchek, David W.

    2014-01-01

    Context: Reconstruction of the anterior cruciate ligament (ACL) is one of the most common surgical procedures, with more than 200,000 ACL tears occurring annually. Although primary ACL reconstruction is a successful operation, success rates still range from 75% to 97%. Consequently, several thousand revision ACL reconstructions are performed annually and are unfortunately associated with inferior clinical outcomes when compared with primary reconstructions. Evidence Acquisition: Data were obtained from peer-reviewed literature through a search of the PubMed database (1988-2013) as well as from textbook chapters and surgical technique papers. Study Design: Clinical review. Level of Evidence: Level 4. Results: The clinical outcomes after revision ACL reconstruction are largely based on level IV case series. Much of the existing literature is heterogenous with regard to patient populations, primary and revision surgical techniques, concomitant ligamentous injuries, and additional procedures performed at the time of the revision, which limits generalizability. Nevertheless, there is a general consensus that the outcomes for revision ACL reconstruction are inferior to primary reconstruction. Conclusion: Excellent results can be achieved with regard to graft stability, return to play, and functional knee instability but are generally inferior to primary ACL reconstruction. A staged approach with autograft reconstruction is recommended in any circumstance in which a single-stage approach results in suboptimal graft selection, tunnel position, graft fixation, or biological milieu for tendon-bone healing. Strength-of-Recommendation Taxonomy (SORT): Good results may still be achieved with regard to graft stability, return to play, and functional knee instability, but results are generally inferior to primary ACL reconstruction: Level B. PMID:25364483

  3. Shoulder electromyography in multidirectional instability.

    PubMed

    Morris, Alfred D; Kemp, Graham J; Frostick, Simon P

    2004-01-01

    We studied shoulder muscle activity in multidirectional instability (MDI) and multidirectional laxity (MDL) of the shoulder, our hypothesis being that altered muscle activity plays a role in their pathogenesis. Six muscles (supraspinatus, infraspinatus, subscapularis, anterior deltoid, middle deltoid, and posterior deltoid) were investigated by use of intramuscular dual fine-wire electrodes in 7 normal shoulders, 5 MDL shoulders, and 6 MDI shoulders. Each subject performed 5 types of exercise (rotation in neutral, 45 degrees of abduction, 90 degrees of abduction, flexion/extension, and abduction/adduction) on an isokinetic muscle dynamometer at two rates, 90 degrees /s and 180 degrees /s. After filtering, rectification, and smoothing, the electromyography signal was normalized by using the peak voltage of the movement cycle. In subjects with MDI, compared with normal subjects, activity patterns of the anterior deltoid were different during rotation in neutral and 90 degrees of abduction, whereas those of the middle and posterior deltoid were different during rotation in 90 degrees of abduction. In subjects with MDL, the posterior deltoid showed increased activity compared with normal subjects during adduction. Activity patterns of the supraspinatus, infraspinatus, and subscapularis appeared similar in both groups. Dual fine-wire electromyography offers insight into the complex role of shoulder girdle muscle function in normal movement and in instability. Altered patterns of shoulder girdle muscle activity and imbalances in muscle forces support the theory that impaired coordination of shoulder girdle muscle activity and inefficiency of the dynamic stabilizers of the glenohumeral joint are involved in the etiology of MDI. Interestingly, the abnormalities are in the deltoid rather than the muscles of the rotator cuff.

  4. Instability of rectangular jets

    NASA Technical Reports Server (NTRS)

    Tam, Christopher K. W.; Thies, Andrew T.

    1992-01-01

    The instability of rectangular jets is investigated using a vortex sheet model. It is shown that such jets support four linearly independent families of instability waves. Within each family there are infinitely many modes. A way to classify these modes according to the characteristics of their mode shapes or eigenfunctions is proposed. A parametric study of the instability wave characteristics has been carried out. A sample of the numerical results is reported here. It is found that the first and third modes of each instability wave family are corner modes. The pressure fluctuations associated with these instability waves are localized near the corners of the jet. The second mode, however, is a center mode with maximum fluctuations concentrated in the central portion of the jet flow. The center mode has the largest spatial growth rate. It is anticipated that as the instability waves propagate downstream the center mode would emerge as the dominant instability of the jet.

  5. Instability of rectangular jets

    NASA Technical Reports Server (NTRS)

    Tam, Christopher K. W.; Thies, Andrew T.

    1992-01-01

    The instability of rectangular jets is investigated using a vortex sheet model. It is shown that such jets support four linearly independent families of instability waves. Within each family there are infinitely many modes. A way to classify these modes according to the characteristics of their mode shapes or eigenfunctions is proposed. A parametric study of the instability wave characteristics has been carried out. A sample of the numerical results is reported here. It is found that the first and third modes of each instability wave family are corner modes. The pressure fluctuations associated with these instability waves are localized near the corners of the jet. The second mode, however, is a center mode with maximum fluctuations concentrated in the central portion of the jet flow. The center mode has the largest spatial growth rate. It is anticipated that as the instability waves propagate downstream the center mode would emerge as the dominant instability of the jet.

  6. Passage of an Anterior Odontoid Screw through Gastrointestinal Tract

    PubMed Central

    Leitner, L.; Brückmann, C. I.; Gilg, M. M.; Bratschitsch, G.; Radl, R.

    2017-01-01

    Purpose. Anterior screw fixation has become a popular surgical treatment method for instable odontoid fractures. Screw loosening and migration are a rare, severe complication following anterior odontoid fixation, which can lead to esophagus perforation and requires revision operation. Methods. We report a case of screw loosening and migration after anterior odontoid fixation, which perforated the esophagus and was excreted without complications in a 78-year-old male patient. Results. A ventral dislocated anterior screw perforated through the esophagus after eight years after implantation and was excreted through the gastrointestinal (GI) tract. At a 6-month follow-up after the event the patient was asymptomatic. Conclusion. Extrusion via the GI tract is not safe enough to be considered as a treatment option for loosened screws. Some improvements could be implemented to prevent such an incident. Furthermore, this case is a fine example that recent preoperative imaging is mandatory before revision surgery for screw loosening. PMID:28194180

  7. Manual testing for ankle instability.

    PubMed

    Wilkin, Emily Jane; Hunt, Adrienne; Nightingale, Elizabeth Jean; Munn, Joanne; Kilbreath, Sharon Lynne; Refshauge, Kathryn Margaret

    2012-12-01

    To assess inter-rater reliability of ankle manual tests. We also correlated the manual tests with the Cumberland Ankle Instability Tool (CAIT). One ankle from each of 60 participants was assessed using four different manual tests (anterior drawer in supine and crook lying, talar tilt, inversion tilt). Three different raters, varying in experience, tested each participant. The CAIT questionnaire was also administered. The study received ethics approval from the University of Sydney Human Research Ethics Committee. Intraclass correlation coefficients (ICC), standard error of the mean (SEM) and percent close agreement (PCA) were used to determine reliability of the four tests. Pearson's correlation coefficients were used to determine relationships between the manual tests and CAIT scores. Inter-rater reliability for the four manual tests was poor regardless of therapist's experience (ICC([1,1]) -0.12 to 0.33; SEM 0.93-1.69). Correlations between the CAIT and manual tests were also low varying between r = -0.12 and -0.42. Inter-rater reliability was poor for manual tests of ankle stability. Reliability may be improved by using a grading scale with fewer intervals. The CAIT scores and manual tests correlated poorly, potentially reflecting the variety of conditions leading to ankle instability. Crown Copyright © 2012. Published by Elsevier Ltd. All rights reserved.

  8. Joint Instability and Osteoarthritis

    PubMed Central

    Blalock, Darryl; Miller, Andrew; Tilley, Michael; Wang, Jinxi

    2015-01-01

    Joint instability creates a clinical and economic burden in the health care system. Injuries and disorders that directly damage the joint structure or lead to joint instability are highly associated with osteoarthritis (OA). Thus, understanding the physiology of joint stability and the mechanisms of joint instability-induced OA is of clinical significance. The first section of this review discusses the structure and function of major joint tissues, including periarticular muscles, which play a significant role in joint stability. Because the knee, ankle, and shoulder joints demonstrate a high incidence of ligament injury and joint instability, the second section summarizes the mechanisms of ligament injury-associated joint instability of these joints. The final section highlights the recent advances in the understanding of the mechanical and biological mechanisms of joint instability-induced OA. These advances may lead to new opportunities for clinical intervention in the prevention and early treatment of OA. PMID:25741184

  9. Ordinary electromagnetic mode instability

    NASA Technical Reports Server (NTRS)

    Cheng, C. Z.

    1974-01-01

    The instability of the ordinary electromagnetic mode propagating perpendicular to an external magnetic field is studied for a single-species plasma with ring velocity distribution. The marginal instability boundaries for both the purely growing mode and the propagating growing modes are calculated from the instability criteria. The dispersion characteristics for various sets of plasma parameters are also given. The typical growth rates are of the order of the cyclotron frequency.

  10. Instability in Rotating Machinery

    NASA Technical Reports Server (NTRS)

    1985-01-01

    The proceedings contain 45 papers on a wide range of subjects including flow generated instabilities in fluid flow machines, cracked shaft detection, case histories of instability phenomena in compressors, turbines, and pumps, vibration control in turbomachinery (including antiswirl techniques), and the simulation and estimation of destabilizing forces in rotating machines. The symposium was held to serve as an update on the understanding and control of rotating machinery instability problems.

  11. Generalities on combustion instabilities

    NASA Astrophysics Data System (ADS)

    Kuentzmann, Paul

    The main manifestations of combustion instabilities are reviewed, and the specific characteristics of instabilities in solid-propellant rocket engines are analyzed, with the Minuteman III third-stage engine and the SRB engine of Titan 34 D considered as examples. The main approaches for predicting combustion instabilities are discussed, including the linear approach based on the acoustic balance, the nonlinear mode-coupling approach, and the nonlinear approach using numerical calculation. Projected directions for future research are also examined.

  12. Clinical Outcomes Following Revision Anterior Shoulder Stabilization

    PubMed Central

    Frank, Rachel M.; Mellano, Chris; Shin, Jason J.; Feldheim, Terrence F.; Mascarenhas, Randhir; Yanke, Adam Blair; Cole, Brian J.; Nicholson, Gregory P.; Romeo, Anthony A.; Verma, Nikhil N.

    2015-01-01

    Objectives: The purpose of this study was to determine the clinical outcomes following revision anterior shoulder stabilization performed either via all-arthroscopic soft tissue repair or via Latarjet coracoid transfer. Methods: A retrospective review of prospectively collected data on 91 shoulders undergoing revision anterior shoulder stabilization was performed. All patients underwent prior soft tissue stabilization; those with prior open bone grafting procedures were excluded. For patients with 25% glenoid bone loss, Latarjet was performed (n=28). Patients were queried regarding recurrent instability (subluxation or dislocation). Clinical outcomes were evaluated using validated patient reported outcome questionnaires including the American Shoulder and Elbow Surgeons (ASES) score, Simple Shoulder Test (SST), visual analog scale (VAS) for pain, and Western Ontario Shoulder Instability Index (WOSI). Results: A total of 63 shoulders in 62 patients (46 males, 16 females) with an average age of 23.2 ± 6.9 years were included in the revision arthroscopy group. At an average follow-up of 46.9 ± 16.8 months (range, 15 to 78), the mean WOSI score was 80.1 (range, 15.0 to 100), and there were significant improvements (p<0.001) in ASES (63.7 to 85.1), SST (6.2 to 9.1), and VAS pain scores (2.89 to 0.81). Recurrent instability occurred in 12 of 63 shoulders (19%); the number of prior surgeries and baseline hyperlaxity were significant risk factors for failure (p<0.001 and p=0.04, respectively). No patients developed clinical or radiographic evidence of arthritis. A total of 28 shoulders in 28 patients (21 male, 7 female) with an average age of 27.5 years (range 14 to 45) were included in the Latarjet group. Thirteen (46%) had more than one previous stabilization attempt. ), the average WOSI score was 71.9, and there were significant improvements (p<0.001) in ASES (65.7 to 87.0), SST (7.2 to 10.3), and VAS (3.1 to 1.1). Recurrent instability occurred in 2 of 28 shoulders

  13. [Recurrent instability and luxation of the shoulder].

    PubMed

    Sedel, L

    1990-04-11

    Instability and recurrent dislocation of the shoulder result from injuries affecting the capsule, ligaments or bones. The positive diagnosis rests on careful clinical investigation where a well-oriented questioning plays an essential role. Paraclinical examinations, such as radiography, ultrasonography, CT and MRI, provide a very accurate assessment of the state of relevant structures. Surgical treatment consists of a stabilizing operation which may be Bankart operation (i.e. suture of the detached capsule onto the anterior part of the glenoid labrum), or a Latarget operation (i.e. screwing of a bony buttress) when the anterior part of the glenoid labrum is deformed by a fracture or worn out by frequent passages of the humeral head. When thoughtfully decided and well executed, these operations regularly give excellent results with resumption of previous activities at the same performance level.

  14. Treatment of hip instability.

    PubMed

    Robbins, G M; Masri, B A; Garbuz, D S; Greidanus, N; Duncan, C P

    2001-10-01

    Instability after total hip arthroplasty is a major source of patient morbidity, second only to aseptic loosening. Certain patient groups have been identified as having a greater risk of instability, including patients undergoing revision arthroplasty as early or late treatment for proximal femoral fractures.

  15. Tibial rotation influences anterior knee stability--a robot-aided in-vitro study.

    PubMed

    Lorenz, Andrea; Röttgerkamp, Heike; Bobrowitsch, Evgenij; Leichtle, Carmen I; Leichtle, Ulf G

    2016-02-01

    Anterior cruciate ligament rupture can lead to symptomatic instability, especially during pivoting activities, which are often associated with increased anterior and rotational tibial loading. Therefore, the purpose of our robot-aided in-vitro study was to analyze the influence of tibial rotation on anterior knee stability under three anterior cruciate ligament conditions. Ten human knee specimens were examined using a robotic system. Anterior tibial translations were measured during anterior force application at internally and externally rotated positions of the tibia (5° steps until 4 Nm was reached) at 20°, 60°, and 90° of flexion. The native knee was compared with the knee with deficient and replaced anterior cruciate ligament. Tibial rotation significantly influenced anterior tibial translation (P<0.001), with differences of up to 12 mm between the largest and smallest anterior translation in the deficient knee. The largest influence of the anterior cruciate ligament on anterior translation was found in slightly externally rotated positions of the tibia (5°-10° at 20° of flexion; 0°-5° at 90° of flexion). Significantly increased anterior tibial translation (up to 7 mm) was measured after anterior cruciate ligament resection, which could be almost completely restored by the replacement (remaining difference<1mm) over a wide range of tibial rotations. Tibial rotation clearly influences anterior tibial translation. Because the greatest effect of the anterior cruciate ligament was found in slightly externally rotated positions of the tibia, increased attention to tibial rotation should be paid when performing the Lachman and anterior drawer tests. Copyright © 2015 Elsevier Ltd. All rights reserved.

  16. Gunshot Injury to the Anterior Arch of Atlas

    PubMed Central

    Park, Jun Hee; Kim, Hyeung Sun; Do, Nam Yong

    2012-01-01

    Penetrating injuries to the upper cervical spine resulting from gunshots are rare in South Korea due to restrictions of gun use. Moreover, gunshot wounds to the upper cervical spine without neurological deficits occur infrequently because of the anatomic location and surrounding essential structures. We present an uncommon case involving the surgical removal of a bullet located in the anterior arch of first cervical vertebra (C1) via a transoral approach without neurological complications or subsequent mechanical instability. PMID:22639715

  17. Examination under anesthetic for occult pelvic ring instability.

    PubMed

    Sagi, H Claude; Coniglione, Franco M; Stanford, Jason H

    2011-09-01

    To describe the technique and results of stress examination with fluoroscopy under anesthesia (EUA) to determine stability and the need for operative stabilization of traumatic pelvic ring injuries. Retrospective chart and radiographic review. Level I trauma center. Skeletally mature patients with traumatic incomplete posterior pelvic ring injuries. Patients were consented for EUA if preoperative radiographs and computed tomographic scanning of the pelvis demonstrated an incomplete injury to the posterior pelvic ring (Orthopaedic Trauma Association [OTA] 61-B type injuries). Patients with nondisplaced anterior compression fractures of the sacral ala without internal rotation or a fracture line exiting the posterior cortex were excluded from this analysis. Similarly, skeletally immature patients or those with complete instability of the pelvic ring (OTA 61-C type injuries) were excluded. All patients meeting inclusion criteria were taken to the operating room, anesthetized, and placed in the supine position for stress examination (EUA) of the pelvic ring using intraoperative dynamic fluoroscopy. Examination consisted of a resting static film followed by internal rotation, external rotation, and push-pull maneuvers of both lower extremities. Each of these maneuvers was performed using the anteroposterior, inlet, and outlet projections, providing a total of 15 distinct images for each patient's examination. The preoperative classification of the pelvic ring injury was then accepted or redefined based on the amount of rotational and translational instability in the axial, coronal, and sagittal planes. The decision to proceed with anterior and/or posterior operative reduction and stabilization was subsequently based on the degree of pelvic ring instability noted during the EUA. A total of sixty-eight patients underwent an EUA of their pelvis by the senior author. Fifty males and 18 females with an average age of 35 years comprised the study group. In all, 37

  18. Under-air staining of the anterior capsule using Trypan blue with a 30 G needle.

    PubMed

    Giammaria, Daniele; Giannotti, Michele; Scopelliti, Angelo; Pellegrini, Giacomo; Giannotti, Bruno

    2013-01-01

    The original technique of staining the anterior capsule of the lens with Trypan blue involves the injection of an air bubble in the anterior chamber. A drawback of this technique is the possible instability of the anterior chamber caused by the sudden exit of air when the dye is injected with the cannula through the side-port incision. Other staining techniques that use viscoelastic substances to increase the stability of the anterior chamber and to dose the injected dye have been described. The authors present an under-air staining technique of the anterior capsule using one drop of Trypan blue injected with a 30 G needle through the peripheral cornea. This procedure prevents the air bubble from escaping the anterior chamber and allows fast and selective staining of the capsule.

  19. Anterior cruciate ligament repair - slideshow

    MedlinePlus

    ... this page: //medlineplus.gov/ency/presentations/100230.htm Anterior cruciate ligament repair - Series—Normal anatomy To use the sharing ... to slide 5 out of 5 Overview The anterior cruciate ligament (ACL) is a ligament in the center of ...

  20. Messenger ribonucleic acid levels in disrupted human anterior cruciate ligaments.

    PubMed

    Lo, Ian K Y; Marchuk, Linda; Hart, David A; Frank, Cyril B

    2003-02-01

    Thirty patients had anterior cruciate ligament reconstruction for ongoing instability. Two groups were defined according to gross morphologic features identified during reconstruction: anterior cruciate ligament disruptions with scars attached to a structure in the joint and disruptions without reattachments. Reverse transcription polymerase chain reaction for a subset of extracellular matrix molecules, proteinases, and proteinase inhibitors was done on samples of scarred anterior cruciate ligament tissue removed during reconstructive surgery. Results of the nonattached scar group showed significantly increased mRNA levels for Type I collagen, and an increased Type I to Type III collagen ratio compared with that for the attached scar group. In the first year after injury, decorin mRNA levels in the nonattached scar group also were significantly higher than in the attached scar group. Biglycan mRNA levels in the nonattached scar group correlated closely with Type I collagen mRNA levels. These results suggest differences in cellular expression in torn anterior cruciate ligaments that attach to structures in the joint versus those which do not. Although the molecular mechanisms responsible for these differences have not been delineated, different molecular signals may influence the gross morphologic features of anterior cruciate ligament disruptions or alternatively, differing gross morphologic features may be subject to different mechanical loads leading to altered molecular expression. However, the finding of endogenous cellular activity in injured anterior cruciate ligaments raises the possibility that this activity may be enhanced to improve outcomes.

  1. Buckling instability in arteries.

    PubMed

    Vandiver, Rebecca M

    2015-04-21

    Arteries can become tortuous in response to abnormal growth stimuli, genetic defects and aging. It is suggested that a buckling instability is a mechanism that might lead to artery tortuosity. Here, the buckling instability in arteries is studied by examining asymmetric modes of bifurcation of two-layer cylindrical structures that are residually stressed. These structures are loaded by an axial force, internal pressure and have nonlinear, anisotropic, hyperelastic responses to stresses. Strain-softening and reduced opening angle are shown to lower the critical internal pressure leading to buckling. In addition, the ratio of the media thickness to the adventitia thickness is shown to have a dramatic impact on arterial instability.

  2. Anterior tarsal tunnel syndrome.

    PubMed

    DiDomenico, Lawrence A; Masternick, Eric B

    2006-07-01

    Compression of the deep peroneal nerve is commonly referred to as anterior tarsal tunnel syndrome. Although rare, this syndrome remains poorly diagnosed. The syndrome is characterized by pain, weakness, and sensory changes of the foot and ankle. Non-operative measures should be attempted to reduce or remove the external compression along the anterior aspect of the foot and ankle. Other options include shoe modifications, cortisone injections,and physical therapy. If conservative management fails to relieve the symptoms, surgical decompression of the entrapped nerve can be performed. The deep peroneal nerve is released from compressive forces in the entrapment site. This can be performed at the more proximal level at the extensor retinaculum or more distally at the level of the tarsal metatarsal site.

  3. [Anterior pseudodiverticulum after laryngectomy].

    PubMed

    Pitzer, G; Oursin, C; Wolfensberger, M

    1998-01-01

    An anterior neopharyngeal pseudodiverticulum is a mucosal pouch located between the tongue and hypopharynx due to an epiglottis-like posterior tissue band that forms after total laryngectomy. This condition has rarely been mentioned in literature. Incidence, symptoms, treatment, and possible etiologic factors were examined. Twenty post-laryngectomy patients were questioned about swallowing disorders and were examined clinically and by barium swallow. Eleven patients were found to have a pseudodiverticulum, of which 9 patients suffered from dysphagia. We found no correlation between the formation of a pseudodiverticulum and radiotherapy or post-laryngectomy complications. All symptomatic patients were treated by dissecting the posterior tissue band endoscopically with a CO2-laser, bringing complete relief of symptoms in 8 of 9 patients. Our study showed that the anterior pseudodiverticulum can be a frequent cause of dysphagia after laryngectomy. It can easily be diagnosed clinically and radiologically. Endoscopic treatment with a CO2-laser is simple and effective.

  4. Anterior capsulolabral reconstruction of the shoulder in athletes.

    PubMed

    Rubenstein, D L; Jobe, F W; Glousman, R E; Kvitne, R S; Pink, M; Giangarra, C E

    1992-09-01

    We did an anterior capsulolabral reconstruction for recurrent subluxation or dislocation of the shoulder in 75 athletes after failure of conservative therapy. Average follow-up was 39 months (range 28 to 60 months). The results were 77% excellent, 75% good, 3% fair, and 5% poor. Seventy-five percent of the professional and 100% of the college baseball players returned to their previous level of competition. Seventy-seven percent of the professional pitchers were able to return to professional pitching. The range of motion at follow-up was full in 79% of the athletes. No infections or nerve injuries occurred. The anterior capsulolabral reconstruction procedure combined with an early rehabilitation program appears to provide an improved outcome compared with previously reported procedures for anterior instability of the shoulder in athletes.

  5. Chronic Ankle Instability: Evolution of the Model

    PubMed Central

    Hiller, Claire E.; Kilbreath, Sharon L.; Refshauge, Kathryn M.

    2011-01-01

    Abstract Context: The Hertel model of chronic ankle instability (CAI) is commonly used in research but may not be sufficiently comprehensive. Mechanical instability and functional instability are considered part of a continuum, and recurrent sprain occurs when both conditions are present. A modification of the Hertel model is proposed whereby these 3 components can exist independently or in combination. Objective: To examine the fit of data from people with CAI to 2 CAI models and to explore whether the different subgroups display impairments when compared with a control group. Design: Cross-sectional study. Patients or Other Participants: Community-dwelling adults and adolescent dancers were recruited: 137 ankles with ankle sprain for objective 1 and 81 with CAI and 43 controls for objective 2. Intervention(s): Two balance tasks and time to recover from an inversion perturbation were assessed to determine if the subgroups demonstrated impairments when compared with a control group (objective 2). Main Outcome Measure(s): For objective 1 (fit to the 2 models), outcomes were Cumberland Ankle Instability Tool score, anterior drawer test results, and number of sprains. For objective 2, outcomes were 2 balance tasks (number of foot lifts in 30 seconds, ability to balance on the ball of the foot) and time to recover from an inversion perturbation. The Cohen d was calculated to compare each subgroup with the control group. Results: A total of 56.5% of ankles (n = 61) fit the Hertel model, whereas all ankles (n = 108) fit the proposed model. In the proposed model, 42.6% of ankles were classified as perceived instability, 30.5% as recurrent sprain and perceived instability, and 26.9% as among the remaining groups. All CAI subgroups performed more poorly on the balance and inversion-perturbation tasks than the control group. Subgroups with perceived instability had greater impairment in single-leg stance, whereas participants with recurrent sprain performed more poorly than

  6. Arthroscopic treatment of glenohumeral instability in soccer goalkeepers.

    PubMed

    Terra, B B; Ejnisman, B; Figueiredo, E A; Andreoli, C V; Pochini, A C; Cohen, C; Arliani, G G; Cohen, M

    2013-06-01

    The aim of this study was to report epidemiologic data and results of arthroscopic treatment of glenohumeral instability in soccer goalkeepers. We included 12 soccer goalkeepers with a mean age of 28.9 years (range 18-45 years) with acute or recurrent traumatic anterior instability who underwent an arthroscopic anatomic capsulolabral repair with bone anchors. Patients who underwent surgery within 4 weeks of the first episode of dislocation were classified as acute instability. The results were evaluated using the Rowe Scale and analyzed according to stability, range of motion and function. The mean follow-up was 3.8 years. The most common mechanism of injury (90% of the cases) was abduction, external rotation and extension. Associated injuries were present in 57.2% of recurrent cases and 20% of acute cases (p<0.293). Excellent or good results were observed in 80% of the cases of acute instability and in 57.2% of cases in the group with recurrent instability (p<0.586). From a total of 12 soccer goalkeepers who underwent the arthroscopic capsulolabral repair, good or excellent results were obtained in 66.6% of cases of glenohumeral instability. Surgical arthroscopic repair was possible in all cases of acute or recurrent instability based on well-established inclusion criteria, i. e., with well-defined exclusion criteria, such as HAGL lesion and significant glenohumeral bone loss, the arthroscopic capsulolabral repair can be carried out in soccer goalkeepers.

  7. Chronic Ankle Instability

    MedlinePlus

    ... Risk for Newly Active Baby Boomers The American College of Foot and Ankle Surgeons has a valuable lesson for Baby Boomers now getting back into fitness and sports: Get your ankles checked for chronic instability caused ...

  8. Evaporatively driven morphological instability

    NASA Astrophysics Data System (ADS)

    Style, Robert W.; Wettlaufer, J. S.

    2007-07-01

    Simple observations of evaporating solutions reveal a complex hierarchy of spatiotemporal instabilities. We analyze one such instability suggested by the qualitative observations of Du and Stone and find that it is driven by a variant of the classical morphological instability in alloy solidification. In the latter case a moving solid-liquid interface is accompanied by a solutally enriched boundary layer that is thermodynamically metastable due to constitutional supercooling. Here, we consider the evaporation of an impure film adjacent to a solid composed of the nonvolatile species. In this case, constitutional supercooling within the film is created by evaporation at the solution-vapor interface and this drives the corrugation of the solid-solution interface across the thickness of the film. The principal points of this simple theoretical study are to suggest an instability mechanism that is likely operative across a broad range of technological and natural systems and to focus future quantitative experimental searches.

  9. Bacterial Genome Instability

    PubMed Central

    Darmon, Elise

    2014-01-01

    SUMMARY Bacterial genomes are remarkably stable from one generation to the next but are plastic on an evolutionary time scale, substantially shaped by horizontal gene transfer, genome rearrangement, and the activities of mobile DNA elements. This implies the existence of a delicate balance between the maintenance of genome stability and the tolerance of genome instability. In this review, we describe the specialized genetic elements and the endogenous processes that contribute to genome instability. We then discuss the consequences of genome instability at the physiological level, where cells have harnessed instability to mediate phase and antigenic variation, and at the evolutionary level, where horizontal gene transfer has played an important role. Indeed, this ability to share DNA sequences has played a major part in the evolution of life on Earth. The evolutionary plasticity of bacterial genomes, coupled with the vast numbers of bacteria on the planet, substantially limits our ability to control disease. PMID:24600039

  10. [Surgical treatment of craniocervical instability. Review paper].

    PubMed

    Alpizar-Aguirre, Armando; Lara Cano, Jorge Giovanni; Rosales, Luis; Míramontes, Victor; Reyes-Sánchez, Alejandro Antonio

    2007-01-01

    The concept of spinal instability is still controversial. Anatomical, biomechanical, clinical and radiographic variants are involved and make the definition complicated. There are solid diagnostic bases in cases of fractures and degenerative disorders; however, pure spinal instability is still under study. The latter may be defined as increased mobility that goes beyond the physiological limits of one vertebra over another in at least one of the three spinal planes of motion. In the case of the craniocervical region, its understanding becomes even more challenging, since its anatomy and physiology are more complex and it is more mobile. Surgical treatment is possible with either an anterior or a posterior approach. Best results are obtained with occipitocervical or atlantoaxial stabilization through a posterior approach, since the anterior one has its limitations. For example, a transoral approach with a bone graft provides compression strength but does not enable immediate appropriate fixation and involves the risk of infection. The choice of the surgical approach must consider the patient's medical status, the specific spine levels involved, the extent of neurological compromise, the X-ray abnormalities and the individual pathology. The goals of surgery are achieved through an appropriate anatomical alignment, assuring the protection of the neural elements and achieving proper spine stabilization with as much preservation of the mobile vertebral segments as possible.

  11. Distal Radioulnar Joint Instability

    PubMed Central

    Mirghasemi, Ali R.; Lee, Daniel J.; Rahimi, Narges; Rashidinia, Shervin

    2015-01-01

    Distal radioulnar joint (DRUJ) instability is a common clinical condition but a frequently missed diagnosis. Both surgical and nonsurgical treatments are possible for chronic cases of DRUJ instability. Nonsurgical treatment can be considered as the primary therapy in less active patients, while surgery should be considered to recover bone and ligament injuries if nonsurgical treatment fails to restore forearm stability and function. The appropriate choice of treatment depends on the individual patient and specific derangement of the DRUJ PMID:26328241

  12. Rotor internal friction instability

    NASA Technical Reports Server (NTRS)

    Bently, D. E.; Muszynska, A.

    1985-01-01

    Two aspects of internal friction affecting stability of rotating machines are discussed. The first role of internal friction consists of decreasing the level of effective damping during rotor subsynchronous and backward precessional vibrations caused by some other instability mechanisms. The second role of internal frication consists of creating rotor instability, i.e., causing self-excited subsynchronous vibrations. Experimental test results document both of these aspects.

  13. State Instability and Terrorism

    DTIC Science & Technology

    2010-01-01

    terrorism is a form ( Durkheim , 1930 [1951]; Useem, 1998). In addition, different types of instability ought to invite different levels of terrorism...society. The effects of the disruption in controls should be to increase levels of nonroutine collective action, of which terrorism is a form ( Durkheim ...instability at the country-level using a modified breakdown theoretical framework. This framework is based especially upon the work of Emile Durkheim

  14. Prediction of Algebraic Instabilities

    NASA Astrophysics Data System (ADS)

    Zaretzky, Paula; King, Kristina; Hill, Nicole; Keithley, Kimberlee; Barlow, Nathaniel; Weinstein, Steven; Cromer, Michael

    2016-11-01

    A widely unexplored type of hydrodynamic instability is examined - large-time algebraic growth. Such growth occurs on the threshold of (exponentially) neutral stability. A new methodology is provided for predicting the algebraic growth rate of an initial disturbance, when applied to the governing differential equation (or dispersion relation) describing wave propagation in dispersive media. Several types of algebraic instabilities are explored in the context of both linear and nonlinear waves.

  15. Equilibrium Electroconvective Instability

    NASA Astrophysics Data System (ADS)

    Rubinstein, I.; Zaltzman, B.

    2015-03-01

    Since its prediction 15 years ago, hydrodynamic instability in concentration polarization at a charge-selective interface has been attributed to nonequilibrium electro-osmosis related to the extended space charge which develops at the limiting current. This attribution had a double basis. On the one hand, it has been recognized that neither equilibrium electro-osmosis nor bulk electroconvection can yield instability for a perfectly charge-selective solid. On the other hand, it has been shown that nonequilibrium electro-osmosis can. The first theoretical studies in which electro-osmotic instability was predicted and analyzed employed the assumption of perfect charge selectivity for the sake of simplicity and so did the subsequent studies of various time-dependent and nonlinear features of electro-osmotic instability. In this Letter, we show that relaxing the assumption of perfect charge selectivity (tantamount to fixing the electrochemical potential of counterions in the solid) allows for the equilibrium electroconvective instability. In addition, we suggest a simple experimental test for determining the true, either equilibrium or nonequilibrium, origin of instability in concentration polarization.

  16. Propagating Instabilities in Solids

    NASA Astrophysics Data System (ADS)

    Kyriakides, Stelios

    1998-03-01

    Instability is one of the factors which limit the extent to which solids can be loaded or deformed and plays a pivotal role in the design of many structures. Such instabilities often result in localized deformation which precipitates catastrophic failure. Some materials have the capacity to recover their stiffness following a certain amount of localized deformation. This local recovery in stiffness arrests further local deformation and spreading of the instability to neighboring material becomes preferred. Under displacement controlled loading the propagation of the transition fronts can be achieved in a steady-state manner at a constant stress level known as the propagation stress. The stresses in the transition fronts joining the highly deformed zone to the intact material overcome the instability nucleation stresses and, as a result, the propagation stress is usually much lower than the stress required to nucleate the instability. The classical example of this class of material instabilities is L/"uders bands which tend to affect mild steels and other metals. Recent work has demonstrated that propagating instabilities occur in several other materials. Experimental and analytical results from four examples will be used to illustrate this point: First the evolution of L=FCders bands in mild steel strips will be revisited. The second example involves the evolution of stress induced phase transformations (austenite to martensite phases and the reverse) in a shape memory alloy under displacement controlled stretching. The third example is the crushing behavior of cellular materials such as honeycombs and foams made from metals and polymers. The fourth example involves the axial broadening/propagation of kink bands in aligned fiber/matrix composites under compression. The microstructure and, as a result, the micromechanisms governing the onset, localization, local arrest and propagation of instabilities in each of the four materials are vastly different. Despite this

  17. Anterior knee pain.

    PubMed

    LLopis, Eva; Padrón, Mario

    2007-04-01

    Anterior knee pain is a common complain in all ages athletes. It may be caused by a large variety of injuries. There is a continuum of diagnoses and most of the disorders are closely related. Repeated minor trauma and overuse play an important role for the development of lesions in Hoffa's pad, extensor mechanism, lateral and medial restrain structures or cartilage surface, however usually an increase or change of activity is referred. Although the direct relation of cartilage lesions, especially chondral, and pain is a subject of debate these lesions may be responsible of early osteoarthrosis and can determine athlete's prognosis. The anatomy and biomechanics of patellofemoral joint is complex and symptoms are often unspecific. Transient patellar dislocation has MR distinct features that provide evidence of prior dislocation and rules our complication. However, anterior knee pain more often is related to overuse and repeated minor trauma. Patella and quadriceps tendon have been also implicated in anterior knee pain, as well as lateral or medial restraint structures and Hoffa's pad. US and MR are excellent tools for the diagnosis of superficial tendons, the advantage of MR is that permits to rule out other sources of intraarticular derangements. Due to the complex anatomy and biomechanic of patellofemoral joint maltracking is not fully understood; plain films and CT allow the study of malalignment, new CT and MR kinematic studies have promising results but further studies are needed. Our purpose here is to describe how imaging techniques can be helpful in precisely defining the origin of the patient's complaint and thus improve understanding and management of these injuries.

  18. Recurrent posterior shoulder instability after rifle shooting.

    PubMed

    Cho, Jae-Ho; Chung, Nam-Su; Song, Hyung-Keun; Lee, Doo-Hyung

    2012-11-01

    Rifle shooting produces a sudden counterforce against the body thorough the anterior shoulder, which may produce a traumatic injury in soldiers. Posterior instability of the shoulder can occur in soldiers who practice rifle shooting. To the authors' knowledge, few reports have examined shooting-related injuries in soldiers. This article describes the case of a 27-year-old male soldier who presented with left shoulder pain and instability after rifle training. He developed symptoms, and presented radiographic findings consistent with a posterior Bankart lesion. Intraoperatively, while in the lateral decubitus position, a posterior portal was created 3 cm inferior and 2 cm lateral to the posterolateral corner of acromion for making a proper angle for inserting anchors. A reverse bony Bankart lesion and adjacent cartilage breakdown at the glenoid rim were noted. An arthroscopic capsulolabral repair was performed with 3-mm bioabsorbable anchors to the glenoid rim. No gross reverse Hill-Sachs lesion or hyaline cartilage lesion was noted. Postoperatively, the arm was supported in a sling with an abduction pillow for 5 weeks. Codman's exercises, scapular protraction exercises, and elbow and wrist exercises were started. Physical therapy focused on reestablishing glenohumeral range of motion and rotator cuff and periscapular muscle strength. Six months postoperatively, the patient had normal scapular kinesis and reported no shoulder pain or symptoms of instability associated with a reverse bony Bankart lesion. Copyright 2012, SLACK Incorporated.

  19. Anterior vitrectomy for shallow anterior chamber after cataract extraction.

    PubMed

    Dottan, S; Levartovsky, S; Oliver, M

    1982-06-01

    Pars plana anterior vitrectomy was performed in 9 patients with shallow anterior chamber after cataract extraction. Five patients had choroidal and/or ciliary body effusion (CCBE), and 4 had aphakic pupillary block (APB). Vitrectomy was performed only after medical treatment failed to restore a normal anterior chamber depth. In all patients the anterior chamber restored during surgery and remained so thereafter, although in patients with CCBE, the fundal pathology subsided days or even months later. The only surgical complication was a longstanding cystoid macular oedema in one patient. Pars plana vitrectomy would appear to have advantages over other surgical techniques, in similar circumstances.

  20. Uveitis (acute anterior).

    PubMed

    Islam, Niaz; Pavesio, Carlos

    2010-04-08

    Anterior uveitis is rare, with an annual incidence of 12/100,000 population, although it is more common in Finland (annual incidence of 23/100,000), probably because of genetic factors, such as high frequency of HLA-B27 in the population. It is often self-limiting, but can, in some cases, lead to complications such as posterior synechiae, cataract, glaucoma, and chronic uveitis. We conducted a systematic review and aimed to answer the following clinical question: What are the effects of anti-inflammatory eye drops on acute anterior uveitis? We searched: Medline, Embase, The Cochrane Library and other important databases up to November 2009 (Clinical Evidence reviews are updated periodically, please check our website for the most up-to-date version of this review). We included harms alerts from relevant organisations such as the US Food and Drug Administration (FDA) and the UK Medicines and Healthcare products Regulatory Agency (MHRA). We found six systematic reviews, RCTs, or observational studies that met our inclusion criteria. We performed a GRADE evaluation of the quality of evidence for interventions. In this systematic review we present information relating to the effectiveness and safety of the following interventions: corticosteroids, mydriatics, and non-steroidal anti-inflammatory drug eye drops.

  1. Genomic Instability in Cancer

    PubMed Central

    Abbas, Tarek; Keaton, Mignon A.; Dutta, Anindya

    2013-01-01

    One of the fundamental challenges facing the cell is to accurately copy its genetic material to daughter cells. When this process goes awry, genomic instability ensues in which genetic alterations ranging from nucleotide changes to chromosomal translocations and aneuploidy occur. Organisms have developed multiple mechanisms that can be classified into two major classes to ensure the fidelity of DNA replication. The first class includes mechanisms that prevent premature initiation of DNA replication and ensure that the genome is fully replicated once and only once during each division cycle. These include cyclin-dependent kinase (CDK)-dependent mechanisms and CDK-independent mechanisms. Although CDK-dependent mechanisms are largely conserved in eukaryotes, higher eukaryotes have evolved additional mechanisms that seem to play a larger role in preventing aberrant DNA replication and genome instability. The second class ensures that cells are able to respond to various cues that continuously threaten the integrity of the genome by initiating DNA-damage-dependent “checkpoints” and coordinating DNA damage repair mechanisms. Defects in the ability to safeguard against aberrant DNA replication and to respond to DNA damage contribute to genomic instability and the development of human malignancy. In this article, we summarize our current knowledge of how genomic instability arises, with a particular emphasis on how the DNA replication process can give rise to such instability. PMID:23335075

  2. The Effectiveness of the Latarjet Procedure for Shoulder Instability in Patients with Epilepsy.

    PubMed

    Ersen, A; Bayram, S; Birisik, F; Atalar, A C; Demirhan, M

    2017-10-04

    Powerful contractions during epileptic seizures may cause shoulder dislocation and instability. The aim of the study is to evaluate the functional and radiographic results of the Latarjet procedure for anterior shoulder dislocation in patients with epilepsy and compare the functional results of these patients with the results of patients without epilepsy. Is latarjet procedure effective in epileptic patients as non-epileptic patients with anterior shoulder instability? 11 shoulders of 9 patients with epileptic seizures causing anterior shoulder instability were evaluated retrospectively. All patients had a Latarjet procedure after neurologic evaluation and treatment arrangement. Epileptic seizures after the operation and shoulder dislocation after a seizure were investigated. For functional evaluation, ROWE, ASES and Constant scores were utilized whereas standard X-Ray views were used for radiologic evaluation. The results of epileptic patients with Latarjet procedure were compared with non-epileptic patients (53 patients, 54 shoulders) for anterior shoulder instability. Three (33%) of the 9 epileptic patients had recurrent seizures after Latarjet procedure, whereas 1 of the 11 shoulders (9%) had dislocation after an epileptic seizure. Functional scores were found to be significantly improved in epileptic (p<0.001) and non- epileptic patients (p<0.001). No significant differences for functional results were found between epileptic and non-epileptic patients after Latarjet procedure for anterior instability (p>0.05). One shoulder of 11 in the patients with epilepsy group (9%) and one shoulder of the 54 shoulders non-epileptic patients group (1.8%) had a redislocation. The rate of postoperative redislocation was significantly higher in patients with epilepsy (p: 0,008). Epileptic patients have a high rate of recurrent seizures even with proper medical treatment. Significant functional improvements and shoulder stability may be achieved after Latarjet procedure in

  3. Scheimpflug imaging in anterior megalophthalmos

    PubMed Central

    Nemeth, Gabor; Hassan, Ziad; Berta, Andras; Modis, Laszlo

    2013-01-01

    We report an anterior megalophthalmos case with decreased corneal thickness and show the findings using Scheimpflug imaging. A 25-year-old male was diagnosed with anterior megalophthalmos. In both eyes, enlarged corneal length was measured. Beside a comparatively good visual acuity, a thin but clear cornea, a fairly deep anterior chamber, and central lens opacity were found. Scheimpflug images were taken using Pentacam HR. Scheimpflug-based imaging can provide us new data at the examination of this syndrome affecting the whole anterior segment. PMID:23275220

  4. Bioengineered anterior cruciate ligament

    NASA Technical Reports Server (NTRS)

    Altman, Gregory (Inventor); Kaplan, David (Inventor); Vunjak-Novakovic, Gordana (Inventor); Martin, Ivan (Inventor)

    2001-01-01

    The present invention provides a method for producing an anterior cruciate ligament ex vivo. The method comprises seeding pluripotent stem cells in a three dimensional matrix, anchoring the seeded matrix by attachment to two anchors, and culturing the cells within the matrix under conditions appropriate for cell growth and regeneration, while subjecting the matrix to one or more mechanical forces via movement of one or both of the attached anchors. Bone marrow stromal cells are preferably used as the pluripotent cells in the method. Suitable matrix materials are materials to which cells can adhere, such as a gel made from collagen type I. Suitable anchor materials are materials to which the matrix can attach, such as Goinopra coral and also demineralized bone. Optimally, the mechanical forces to which the matrix is subjected mimic mechanical stimuli experienced by an anterior cruciate ligament in vivo. This is accomplished by delivering the appropriate combination of tension, compression, torsion, and shear, to the matrix. The bioengineered ligament which is produced by this method is characterized by a cellular orientation and/or matrix crimp pattern in the direction of the applied mechanical forces, and also by the production of collagen type I, collagen type III, and fibronectin proteins along the axis of mechanical load produced by the mechanical forces. Optimally, the ligament produced has fiber bundles which are arranged into a helical organization. The method for producing an anterior cruciate ligament can be adapted to produce a wide range of tissue types ex vivo by adapting the anchor size and attachment sites to reflect the size of the specific type of tissue to be produced, and also adapting the specific combination of forces applied, to mimic the mechanical stimuli experienced in vivo by the specific type of tissue to be produced. The methods of the present invention can be further modified to incorporate other stimuli experienced in vivo by the

  5. Entanglement production at Instabilities

    NASA Astrophysics Data System (ADS)

    Hackl, Lucas; Bianchi, Eugenio; Yokomizo, Nelson

    2016-03-01

    Instabilities play a major role in various areas of physics. In this talk, I will present some new results on how instabilities produce entanglement between subsystems. We study the asymptotic behavior of the entanglement entropy when we evolve a squeezed vacuum with an unstable quadratic Hamiltonian. We show that in this setting the entanglement entropy always grows linearly with a slope determined by the classical Lyapunov exponents of the system, resembling the classical Kolmogorov-Sinai entropy rate. Our theorem applies to all bosonic quantum field theories with quadratic coupling, including the scalar Schwinger effect, the inverted mass scalar field and various complex field theory models.

  6. 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.

  7. Anterior hip pain.

    PubMed

    O'Kane, J W

    1999-10-15

    Anterior hip pain is a common complaint with many possible causes. Apophyseal avulsion and slipped capital femoral epiphysis should not be overlooked in adolescents. Muscle and tendon strains are common in adults. Subsequent to accurate diagnosis, strains should improve with rest and directed conservative treatment. Osteoarthritis, which is diagnosed radiographically, generally occurs in middle-aged and older adults. Arthritis in younger adults should prompt consideration of an inflammatory cause. A possible femoral neck stress fracture should be evaluated urgently to prevent the potentially significant complications associated with displacement. Patients with osteitis pubis should be educated about the natural history of the condition and should undergo physical therapy to correct abnormal pelvic mechanics. "Sports hernias," nerve entrapments and labral pathologic conditions should be considered in athletic adults with characteristic presentations and chronic symptoms. Surgical intervention may allow resumption of pain-free athletic activity.

  8. [Injuries of the anterior cruciate ligament in athletes].

    PubMed

    Shafizadeh, S; Schneider, M M; Bouillon, B

    2014-10-01

    Anterior cruciate ligament ruptures represent serious injuries for athletes which are often associated with accompanying injuries and lead to relevant kinematic alterations in the femorotibial roll-glide mechanism of the knee joint. Instability resulting in recurrent giving way events, as well as instability-related meniscal and cartilage lesions can cause functional long-term impairment that may limit the athlete's career. Anterior cruciate ligament replacement is therefore considered to be the gold standard for recovery of physical performance and to prevent secondary meniscal and cartilage damage. Continuous changes in the reconstruction of the anterior cruciate ligament have led to a variety of different methods, including graft choice, fixation devices and surgical techniques, which support the consideration of individual requirements of the athlete as well as sport-specific aspects. One of the main factors for restoring stability and the physiological kinematic roll-glide mechanism of the knee is an anatomical tunnel placement as well as a stable graft fixation in the tibia and femur. By achieving of these fundamental technical requirements an early functional rehabilitation and accelerated recovery of neuromuscular skills, strength and coordination can be achieved, so that an early return to sport activities is possible.

  9. Anterior knee pain after total knee arthroplasty: a narrative review.

    PubMed

    Petersen, Wolf; Rembitzki, Ingo Volker; Brüggemann, Gerd-Peter; Ellermann, Andree; Best, Raymond; Koppenburg, Andreas Gösele-; Liebau, Christian

    2014-02-01

    Anterior knee pain is one of the most common causes of persistent problems after implantation of a total knee replacement. It can occur in patients with or without patellar resurfacing. As a result of the surgical procedure itself many changes can occur which may affect the delicate interplay of the joint partners in the patello-femoral joint. Functional causes of anterior knee pain can be distinguished from mechanical causes. The functional causes concern disorders of inter- and intramuscular coordination, which can be attributed to preoperative osteoarthritis. Research about anterior knee pain has shown that not only the thigh muscles but also the hip and trunk stabilising muscles may be responsible for the development of a dynamic valgus malalignment. Dynamic valgus may be a causative factor for patellar maltracking. The mechanical causes of patello-femoral problems after knee replacement can be distinguished according to whether they increase instability in the joint, increase joint pressure or whether they affect the muscular lever arms. These causes include offset errors, oversizing, rotational errors of femoral or tibial component, instability, maltracking and chondrolysis, patella baja and aseptic loosening. In these cases, reoperation or revision is often necessary.

  10. Arthroscopic repair of chronic bony bankart lesion using a low anterior portal.

    PubMed

    Brand, Jefferson C; Westerberg, Paul

    2012-12-01

    We describe the repair of a chronic bony Bankart lesion in a case with recurrent instability using standard techniques and equipment for addressing anteroinferior glenohumeral instability. A 25-year-old man with recurrent instability and a chronic bony Bankart lesion with a Hill-Sachs lesion was treated. The inferior 2 sutures and knotless anchors are placed through a low anterior portal, which improves the angle of approach to the inferior portion of the glenoid that is fractured. The knotless anchors are impacted through the low anterior portal, just superior to the level of the suture, as the fragment tends to retract medially and inferiorly, with the drill guide slightly on the face of the glenoid. The superior-anterior portal adjacent to the biceps tendon gives a better view of the glenoid articular cartilage position of the anchors required to restore the anatomic location of the fracture fragment. The low anterior portal improved and simplified the reduction of the fracture fragment to the glenoid neck by allowing access to the anterior-inferior bony Bankart lesion that was repairable with suture and knotless anchors using standardized techniques.

  11. Arthroscopic Repair of Chronic Bony Bankart Lesion Using a Low Anterior Portal

    PubMed Central

    Brand, Jefferson C.; Westerberg, Paul

    2012-01-01

    We describe the repair of a chronic bony Bankart lesion in a case with recurrent instability using standard techniques and equipment for addressing anteroinferior glenohumeral instability. A 25-year-old man with recurrent instability and a chronic bony Bankart lesion with a Hill-Sachs lesion was treated. The inferior 2 sutures and knotless anchors are placed through a low anterior portal, which improves the angle of approach to the inferior portion of the glenoid that is fractured. The knotless anchors are impacted through the low anterior portal, just superior to the level of the suture, as the fragment tends to retract medially and inferiorly, with the drill guide slightly on the face of the glenoid. The superior-anterior portal adjacent to the biceps tendon gives a better view of the glenoid articular cartilage position of the anchors required to restore the anatomic location of the fracture fragment. The low anterior portal improved and simplified the reduction of the fracture fragment to the glenoid neck by allowing access to the anterior-inferior bony Bankart lesion that was repairable with suture and knotless anchors using standardized techniques. PMID:23766999

  12. [Psychodynamics of childhood instability].

    PubMed

    Flavigny, C

    1988-01-01

    This work focuses on the Anglo-Saxon idea concerning "hyperactivity" and "hyperkinesis" and the French-language idea of "child psycho-motor instability". The author's own personal study (having two separate parts, on the one hand studying the psychic functioning of parent and their interaction with their child, and on the other, studying material gathered on the individual psychotherapy of unstable children), goes along with the French school of thought, highlighting the extent of incestuous sexual advances toward children (especially boys) in the family unit and the sexual nature (in the sense of child sexuality) of this excitement as the source of their instability, justifying a comparison between the unstable child and a Don Juan-type of instability. What comes out is epistemological thinking on Anglo-Saxon and French-language ideas, in particular criticism of the pre-suppositions in the Anglo-Saxon way of seeing things, which seems only to envisage the characterization of a syndromic range, rather than an organic etiology, this being more often implicit; distanced by the idea of psychodynamics, which predominate in the French-language studies, integrating the symptom of "psycho-motor instability" in the general "wholeness" of the child and evaluating ways of parent-child interaction.

  13. Partial Torus Instability

    NASA Astrophysics Data System (ADS)

    Olmedo, Oscar; Zhang, J.

    2010-05-01

    Flux ropes are now generally accepted to be the magnetic configuration of Coronal Mass Ejections (CMEs), which may be formed prior or during solar eruptions. In this study, we model the flux rope as a current-carrying partial torus loop with its two footpoints anchored in the photosphere, and investigate its instability in the context of the torus instability (TI). Previous studies on TI have focused on the configuration of a circular torus and revealed the existence of a critical decay index. Our study reveals that the critical index is a function of the fractional number of the partial torus, defined by the ratio between the arc length of the partial torus above the photosphere and the circumference of a circular torus of equal radius. We refer to this finding the partial torus instability (PTI). It is found that a partial torus with a smaller fractional number has a smaller critical index, thus requiring a more gradually decreasing magnetic field to stabilize the flux rope. On the other hand, the partial torus with a larger fractional number has a larger critical index. In the limit of a circular torus when the fractional number approaches one, the critical index goes to a maximum value that depends on the distribution of the external magnetic field. We demonstrate that the partial torus instability helps us to understand the confinement, growth, and eventual eruption of a flux rope CME.

  14. Electromagnetic ion beam instabilities

    NASA Technical Reports Server (NTRS)

    Gary, S. P.; Foosland, D. W.; Smith, C. W.; Lee, M. A.; Goldstein, M. L.

    1984-01-01

    The linear theory of electromagnetic instabilities driven by an energetic ion beam streaming parallel to a magnetic field in a homogeneous Vlasov plasma is considered. Numerical solutions of the full dispersion equation are presented. At propagation parallel to the magnetic field, there are four distinct instabilities. A sufficiently energetic beam gives rise to two unstable modes with right-hand polarization, one resonant with the beam, the other nonresonant. A beam with sufficiently large T (perpendicular to B)/T (parallel to B) gives rise to the left-hand ion cyclotron anisotropy instability at relatively small beam velocities, and a sufficiently hot beam drives unstable a left-hand beam resonant mode. The parametric dependences of the growth rates for the three high beam velocity instabilities are presented here. In addition, some properties at oblique propagation are examined. It is demonstrated that, as the beam drift velocity is increased, relative maxima in growth rates can arise at harmonics of the ion cyclotron resonance for both right and left elliptically polarized modes.

  15. Multidirectional Shoulder Instability: Treatment

    PubMed Central

    Ruiz Ibán, Miguel Angel; Díaz Heredia, Jorge; García Navlet, Miguel; Serrano, Francisco; Santos Oliete, María

    2017-01-01

    Background: The treatment of multidirectional instability of the shoulder is complex. The surgeon should have a clear understanding of the role of hiperlaxity, anatomical variations, muscle misbalance and possible traumatic incidents in each patient. Methods: A review of the relevant literature was performed including indexed journals in English and Spanish. The review was focused in both surgical and conservative management of multidirectional shoulder instability. Results: Most patients with multidirectional instability will be best served with a period of conservative management with physical therapy; this should focus in restoring strength and balance of the dynamic stabilizers of the shoulder. The presence of a significant traumatic incident, anatomic alterations and psychological problems are widely considered to be poor prognostic factors for conservative treatment. Patients who do not show a favorable response after 3 months of conservative treatment seem to get no benefit from further physical therapy. When conservative treatment fails, a surgical intervention is warranted. Both open capsular shift and arthroscopic capsular plication are considered to be the treatment of choice in these patients and have similar outcomes. Thermal or laser capsuloraphy is no longer recommended. Conclusion: Multidirectional instability is a complex problem. Conservative management with focus on strengthening and balancing of the dynamic shoulder stabilizers is the first alternative. Some patients will fare poorly and require either open or arthroscopic capsular plication.

  16. [Anterior cervical hypertrichosis: case report].

    PubMed

    Orozco-Gutiérrez, Mario H; Sánchez-Corona, José; García-Ortiz, José E; Castañeda-Cisneros, Gema; Dávalos-Rodríguez, Nory O; Corona-Rivera, Jorge R; García-Cruz, Diana

    2016-10-01

    The non-syndromic anterior cervical hypertrichosis (OMIM N° 600457) is a genetic disorder characterized by a patch of hair at the level of the laryngeal prominence. We present a 12-year-old boy with anterior cervical hypertrichosis and mild generalized hypertrichosis. He has no neurological, ophthalmological or skeletal anomalies. The clinical follow up is 10 years.

  17. Team physician #7. A comparative study of functional bracing in the anterior cruciate deficient knee.

    PubMed

    Rink, P C; Scott, R A; Lupo, R L; Guest, S J

    1989-06-01

    We evaluated the ability of three functional knee braces, (CTI, OTI, and TS7) to control anterolateral rotary instability of the knee. Fourteen subjects, none of elite athletic status, with arthroscopically proven anterior cruciate deficient knees were selected. The subjects evaluated each brace after one-month periods, and then underwent testing with physical examinations, KT-1000 arthrometry, and timed running events. All braces reduced subjective symptoms of knee instability. Different subjects preferred different braces. KT-1000 testing showed a reduction in anterior tibial displacement for all braces; however, this reduction did not increase as forces increased. A timed figure-of-eight running event did not show any functional advantage of bracing. Five subluxation events occurred in four subjects while braced. Functional braces appear to have a role in the anterior cruciate deficient knee, but only in conjunction with activity modification.

  18. Anterior knee pain in the young athlete: diagnosis and treatment.

    PubMed

    Kodali, Pradeep; Islam, Andrew; Andrish, Jack

    2011-03-01

    The underlying etiology of anterior knee pain has been extensively studied. Despite many possible causes, often times the diagnosis is elusive. The most common causes in the young athlete are osteosynchondroses, patellar peritendinitis and tendinosis, synovial impingement, malalignment, and patellar instability. Less common causes are osteochondritis dissecans and tumors. It is always important to rule out underlying hip pathology and infections. When a diagnosis cannot be established, the patient is usually labeled as having idiopathic anterior knee pain. A careful history and physical examination can point to the correct diagnosis in the majority of cases. For most of these conditions, treatment is typically nonoperative with surgery reserved for refractory pain for an established diagnosis.

  19. Chronic ankle instability: Arthroscopic anatomical repair.

    PubMed

    Arroyo-Hernández, M; Mellado-Romero, M; Páramo-Díaz, P; García-Lamas, L; Vilà-Rico, J

    Ankle sprains are one of the most common injuries. Despite appropriate conservative treatment, approximately 20-40% of patients continue to have chronic ankle instability and pain. In 75-80% of cases there is an isolated rupture of the anterior talofibular ligament. A retrospective observational study was conducted on 21 patients surgically treated for chronic ankle instability by means of an arthroscopic anatomical repair, between May 2012 and January 2013. There were 15 men and 6 women, with a mean age of 30.43 years (range 18-48). The mean follow-up was 29 months (range 25-33). All patients were treated by arthroscopic anatomical repair of anterior talofibular ligament. Four (19%) patients were found to have varus hindfoot deformity. Associated injuries were present in 13 (62%) patients. There were 6 cases of osteochondral lesions, 3 cases of posterior ankle impingement syndrome, and 6 cases of peroneal pathology. All these injuries were surgically treated in the same surgical time. A clinical-functional study was performed using the American Orthopaedic Foot and Ankle Society (AOFAS) score. The mean score before surgery was 66.12 (range 60-71), and after surgery it increased up to a mean of 96.95 (range 90-100). All patients were able to return to their previous sport activity within a mean of 21.5 weeks (range 17-28). Complications were found in 3 (14%) patients. Arthroscopic anatomical ligament repair technique has excellent clinical-functional results with a low percentage of complications, and enables patients to return to their previous sport activity within a short period of time. Copyright © 2016 SECOT. Publicado por Elsevier España, S.L.U. All rights reserved.

  20. Instability in poroelastic media

    NASA Astrophysics Data System (ADS)

    Pramanik, Satyajit; Wettlaufer, John

    2016-11-01

    Fluid flow in deformable porous materials, which play significant role in different biological and geological systems of wide range of scales, is a highly nonlinear problem. Feedback from the elastic deformation of the solid skeleton on the fluid flow and vice-versa gives rise to pattern formation in the porosity structure of the skeleton. We view some of these patterns as instabilities of the coupled fluid-solid system. Due to highly nonlinear nature of the problem, very little has been understood about this instability. Here, we use a minimal poroelastic theory to understand the pattern formation in a fluid-saturated poroelastic material and discuss the similarities/differences with viscous fingering in non-deformable porous media.

  1. Open field lines instabilities

    SciTech Connect

    Pozzoli, R. |

    1995-09-01

    The results of some recent theoretical papers dealing with flute-like instabilities in the scrape-off layer of a tokamak with limiter configuration, where the magnetic field intersects conducting walls, are briefly recalled. Attention is then paid to the instability driven by the electron temperature gradient across the field in conjunction with the formation of the Debye sheath at the boundary, and to the effects due to the inclination of the end walls with respect to the magnetic field. When a divertor configuration is considered, important modifications are found owing to the strong deformations of the flux tubes passing near the {ital x}-point, which contrast the onset of flute-like perturbations, and to the stochasticity of field lines that can be excited by magnetic field perturbations. {copyright} {ital 1995 American Institute of Physics.}

  2. Modulation instability: The beginning

    NASA Astrophysics Data System (ADS)

    Noskov, Roman; Belov, Pavel; Kivshar, Yuri

    2012-11-01

    The study of metal nanoparticles plays a central role in the emerging novel technologies employing optics beyond the diffraction limit. Combining strong surface plasmon resonances, high intrinsic nonlinearities and deeply subwavelength scales, arrays of metal nanoparticles offer a unique playground to develop novel concepts for light manipulation at the nanoscale. Here we suggest a novel principle to control localized optical energy in chains of nonlinear subwavelength metal nanoparticles based on the fundamental nonlinear phenomenon of modulation instability. In particular, we demonstrate that modulation instability can lead to the formation of long-lived standing and moving nonlinear localized modes of several distinct types such as bright and dark solitons, oscillons, and domain walls. We analyze the properties of these nonlinear localized modes and reveal different scenarios of their dynamics including transformation of one type of mode to another. We believe this work paves a way towards the development of nonlinear nanophotonics circuitry.

  3. Instabilities in sensory processes

    NASA Astrophysics Data System (ADS)

    Balakrishnan, J.

    2014-07-01

    In any organism there are different kinds of sensory receptors for detecting the various, distinct stimuli through which its external environment may impinge upon it. These receptors convey these stimuli in different ways to an organism's information processing region enabling it to distinctly perceive the varied sensations and to respond to them. The behavior of cells and their response to stimuli may be captured through simple mathematical models employing regulatory feedback mechanisms. We argue that the sensory processes such as olfaction function optimally by operating in the close proximity of dynamical instabilities. In the case of coupled neurons, we point out that random disturbances and fluctuations can move their operating point close to certain dynamical instabilities triggering synchronous activity.

  4. Wrist Instability After Injury

    PubMed Central

    Muminagic, Sahib; Kapidzic, Tarik

    2012-01-01

    Fractures of the bones that make the wrist joint together with injury to the ligaments and joint capsules are frequent traumas. It can cause besides limited movement also the pathological mobility. These mild injuries often do not provide the degree of recognizable symptoms and signs. They are diagnosed by X-ray imaging, stress images. Before arthrography was an important method, but nowadays arthroscopy has the advantage. Fresh bone and ligament injuries can be and should be repaired in the early posttraumatic period. Unrecognized and undiagnosed injuries are leading to instability of the wrist, to motion abnormalities or impingement overload syndrome. In the treatment of instability important place have reconstruction of the ligaments and arthrodesis of the wrist. PMID:23678318

  5. [Orthostatic tremor inducing instability].

    PubMed

    Manrique-Huarte, Raquel; Arcocha, Juan; Pérez-Fernández, Nicolás

    2012-01-01

    Orthostatic tremor (OT) is a neurological disease of unknown aetiology. It is defined by the presence of a 10-20 Hz tremor in the legs while standing still. Symptoms described are dizziness and instability that diminish if the patient sits down or leans on something; drinking small amounts of alcohol significantly reduces OT. Due to the dizziness and/or unsteadiness, these patients are usually referred to the neuro-otology department. We report 4 cases diagnosed with OT. The diagnosis of OT should be considered for patients with instability. The clinical history is a key factor to suspect this entity, and the diagnosis is given by the register of 10-20 Hz contractions on limb electromyography. Treatment for this disease consists of medical treatment; the first option is clonazepam.

  6. Modulation instability: The beginning

    NASA Astrophysics Data System (ADS)

    Zakharov, V. E.; Ostrovsky, L. A.

    2009-03-01

    We discuss the early history of an important field of “sturm and drang” in modern theory of nonlinear waves. It is demonstrated how scientific demand resulted in independent and almost simultaneous publications by many different authors on modulation instability, a phenomenon resulting in a variety of nonlinear processes such as envelope solitons, envelope shocks, freak waves, etc. Examples from water wave hydrodynamics, electrodynamics, nonlinear optics, and convection theory are given.

  7. Anterior knee pain: an update of physical therapy.

    PubMed

    Werner, Suzanne

    2014-10-01

    Anterior knee pain is one of the most common knee problems in physically active individuals. The reason for anterior knee pain has been suggested to be multifactorial with patella abnormalities or extensor mechanism disorder leading to patellar malalignment during flexion and extension of the knee joint. Some patients complain mostly of non-specific knee pain, while others report patellar instability problems. The patients present with a variety of symptoms and clinical findings, meaning that a thorough clinical examination is the key for optimal treatment. Weakness of the quadriceps muscle, especially during eccentric contractions, is usually present in the majority of anterior knee pain patients. However, irrespective of whether pain or instability is the major problem, hypotrophy and reduced activity of the vastus medialis are often found, which result in an imbalance between vastus medialis and vastus lateralis. This imbalance needs to be corrected before quadriceps exercises are started. The non-operative rehabilitation protocol should be divided into different phases based on the patient's progress. The goal of the first phase is to reduce pain and swelling, improve the balance between vastus medialis and vastus lateralis, restore normal gait, and decrease loading of the patello-femoral joint. The second phase should include improvement of postural control and coordination of the lower extremity, increase of quadriceps strength and when needed hip muscle strength, and restore good knee function. The patient should be encouraged to return to or to start with a suitable regular physical exercise. Therefore, the third phase should include functional exercises. Towards the end of the treatment, single-leg functional tests and functional knee scores should be used for evaluating clinical outcome. A non-operative treatment of patients with anterior knee pain should be tried for at least 3 months before considering other treatment options.

  8. Combustion instability analysis

    NASA Technical Reports Server (NTRS)

    Chung, T. J.

    1990-01-01

    A theory and computer program for combustion instability analysis are presented. The basic theoretical foundation resides in the concept of entropy-controlled energy growth or decay. Third order perturbation expansion is performed on the entropy-controlled acoustic energy equation to obtain the first order integrodifferential equation for the energy growth factor in terms of the linear, second, and third order energy growth parameters. These parameters are calculated from Navier-Stokes solutions with time averages performed on as many Navier-Stokes time steps as required to cover at least one peak wave period. Applications are made for a 1-D Navier-Stokes solution for the Space Shuttle Main Engine (SSME) thrust chamber with cross section area variations taken into account. It is shown that instability occurs when the mean pressure is set at 2000 psi with 30 percent disturbances. Instability also arises when the mean pressure is set at 2935 psi with 20 percent disturbances. The system with mean pressures and disturbances more adverse that these cases were shown to be unstable.

  9. Robust dynamic mitigation of instabilities

    SciTech Connect

    Kawata, S.; Karino, T.

    2015-04-15

    A dynamic mitigation mechanism for instability growth was proposed and discussed in the paper [S. Kawata, Phys. Plasmas 19, 024503 (2012)]. In the present paper, the robustness of the dynamic instability mitigation mechanism is discussed further. The results presented here show that the mechanism of the dynamic instability mitigation is rather robust against changes in the phase, the amplitude, and the wavelength of the wobbling perturbation applied. Generally, instability would emerge from the perturbation of the physical quantity. Normally, the perturbation phase is unknown so that the instability growth rate is discussed. However, if the perturbation phase is known, the instability growth can be controlled by a superposition of perturbations imposed actively: If the perturbation is induced by, for example, a driving beam axis oscillation or wobbling, the perturbation phase could be controlled, and the instability growth is mitigated by the superposition of the growing perturbations.

  10. Atlantoaxial instability after a header in an amateur soccer player.

    PubMed

    Werle, Stephan; Nahleh, Kais Abu; Boehm, Heinrich

    2015-03-01

    Case report and literature review. To report a unique case of atlantoaxial instability after a header in a 37-year-old amateur soccer player and to discuss the injury pattern in relation to the impact of heading. Although there is potential for cervical spine injuries, the rates in soccer are low compared with other contact or even noncontact sports. No cases of acute post-traumatic atlantoaxial instability after heading have ever been reported in a MEDLINE-listed article. A 37-year-old male soccer player experienced acute upper neck pain and transient quadriplegia after heading a long-distance ball on 2 occasions during a match. Imaging revealed atlantoaxial instability. Persistent neurological symptoms on conservative treatment led to his referral to our department. The considerable instability required surgical intervention. Transarticular C1-C2 fixation and posterior fusion with structural iliac crest grafting were performed. The procedure immediately led to complete relief of the neurological symptoms. After an uneventful postoperative recovery, follow-up at 9 months revealed solid fusion. The patient remained symptom free. Heading the ball in soccer can potentially lead to atlantoaxial instability. Ligamentous damage can theoretically be caused by anteriorly directed and rotational overload. However, the causative mechanism remains unclear. Diagnostic workup should consider dynamic imaging in players with transient neurological symptoms after minor trauma to the cervical spine. N/A.

  11. Anterior Knee Pain (Chondromalacia Patellae).

    ERIC Educational Resources Information Center

    Garrick, James G.

    1989-01-01

    This article presents a pragmatic approach to the definition, diagnosis, and management of anterior knee pain. Symptoms and treatment are described. Emphasis is on active involvement of the patient in the rehabilitation exercise program. (IAH)

  12. Anterior Knee Pain (Chondromalacia Patellae).

    ERIC Educational Resources Information Center

    Garrick, James G.

    1989-01-01

    This article presents a pragmatic approach to the definition, diagnosis, and management of anterior knee pain. Symptoms and treatment are described. Emphasis is on active involvement of the patient in the rehabilitation exercise program. (IAH)

  13. Contributing factors to chronic ankle instability.

    PubMed

    Hubbard, Tricia J; Kramer, Lauren C; Denegar, Craig R; Hertel, Jay

    2007-03-01

    The development of repetitive ankle sprains and persistent symptoms after initial ankle sprain has been termed chronic ankle instability (CAI). There is no clear indication of which measures are most important in discriminating between individuals with and without CAI. Thirty subjects with unilateral CAI and controls had measures of ankle laxity and hypomobility, static and dynamic balance, ankle and hip strength, lower extremity alignments, and flexibility taken on both limbs. Based on comparisons of CAI ankles and side-matched limbs in controls, the measures significantly predictive of CAI were increased inversion laxity (r(2) change = 0.203), increased anterior laxity (r(2) change = 0.11), more missed balance trials (r(2) change = 0.094), and lower plantarflexion to dorsiflexion peak torque (r(2) change = 0.052). Symmetry indices comparing the side-to-side differences of each measure also were calculated for each dependent variable and compared between groups. The measures significantly predictive of CAI were decreased anterior reach (r(2) change = 0.185), decreased plantarflexion peak torque (r(2) change = 0.099), decreased posterior medial reach (r(2) change = 0.094), and increased inversion laxity (r(2) change = 0.041). The results of this study elucidate the specific measures that best discriminate between individuals with and without CAI. Both mechanical (anterior and inversion laxity) and functional (strength, dynamic balance) insufficiencies significantly contribute to the etiology of CAI. Prevention of CAI may be possible with proper initial management of the acute injury with rehabilitation aimed at those factors that best discriminate between individuals with and without CAI.

  14. Suppressing shape instabilities to discover the Bjerknes force instability (L).

    PubMed

    Alibakhshi, Mohammad A; Holt, R Glynn

    2011-11-01

    For sufficiently strong acoustic forcing in a standing wave field, subresonant size bubbles are predicted to be repelled from the pressure antinode. Single bubble sonoluminescence (SBSL) conditions in water do not allow the observation of this instability. This study investigates the possibility that increasing the viscosity of the host liquid can preferentially suppress shape instabilities of a bubble and allow SBSL experiments to be limited by the Bjerknes force instability.

  15. Return to Sports and Recurrences After Arthroscopic Anterior Shoulder Stabilization in Martial Arts Athletes

    PubMed Central

    Ranalletta, Maximiliano; Rossi, Luciano A.; Sirio, Adrian; Dilernia, Fernando Diaz; Bertona, Agustin; Maignon, Gastón D.; Bongiovanni, Santiago L.

    2017-01-01

    Background: The high demands to the glenohumeral joint and the violent shoulder blows experienced during martial arts (MA) could compromise return to sports and increase the recurrence rate after arthroscopic stabilization for anterior shoulder instability in these athletes. Purpose: To report the functional outcomes, return to sports, and recurrences in a series of MA athletes with anterior shoulder instability treated with arthroscopic stabilization with suture anchors. Study Design: Case series; Level of evidence, 4. Methods: A total of 20 consecutive MA athletes were treated for anterior shoulder instability at a single institution between January 2008 and December 2013. Range of motion (ROM), the Rowe score, a visual analog scale (VAS), and the Athletic Shoulder Outcome Scoring System (ASOSS) were used to assess functional outcomes. Return-to-sport and recurrence rates were also evaluated. Results: The mean age at the time of surgery was 25.4 years (range, 18-35 years), and the mean follow-up was 71 months (range, 36-96 months). No significant difference in preoperative and postoperative shoulder ROM was found. The Rowe, VAS, and ASOSS scores showed statistical improvement after surgery (P < .001). In all, 19 athletes (95%) returned to sports. However, only 60% achieved ≥90% recovery after surgery. The recurrence rate was 20%. Conclusion: In this retrospective study of a consecutive cohort of MA athletes, arthroscopic anterior shoulder stabilization significantly improved functional scores. However, only 60% of the athletes achieved the same level of competition, and there was a 20% recurrence rate. PMID:28932751

  16. Return to Sports and Recurrences After Arthroscopic Anterior Shoulder Stabilization in Martial Arts Athletes.

    PubMed

    Ranalletta, Maximiliano; Rossi, Luciano A; Sirio, Adrian; Dilernia, Fernando Diaz; Bertona, Agustin; Maignon, Gastón D; Bongiovanni, Santiago L

    2017-09-01

    The high demands to the glenohumeral joint and the violent shoulder blows experienced during martial arts (MA) could compromise return to sports and increase the recurrence rate after arthroscopic stabilization for anterior shoulder instability in these athletes. To report the functional outcomes, return to sports, and recurrences in a series of MA athletes with anterior shoulder instability treated with arthroscopic stabilization with suture anchors. Case series; Level of evidence, 4. A total of 20 consecutive MA athletes were treated for anterior shoulder instability at a single institution between January 2008 and December 2013. Range of motion (ROM), the Rowe score, a visual analog scale (VAS), and the Athletic Shoulder Outcome Scoring System (ASOSS) were used to assess functional outcomes. Return-to-sport and recurrence rates were also evaluated. The mean age at the time of surgery was 25.4 years (range, 18-35 years), and the mean follow-up was 71 months (range, 36-96 months). No significant difference in preoperative and postoperative shoulder ROM was found. The Rowe, VAS, and ASOSS scores showed statistical improvement after surgery (P < .001). In all, 19 athletes (95%) returned to sports. However, only 60% achieved ≥90% recovery after surgery. The recurrence rate was 20%. In this retrospective study of a consecutive cohort of MA athletes, arthroscopic anterior shoulder stabilization significantly improved functional scores. However, only 60% of the athletes achieved the same level of competition, and there was a 20% recurrence rate.

  17. Radiation Induced Genomic Instability

    SciTech Connect

    Morgan, William F.

    2011-03-01

    Radiation induced genomic instability can be observed in the progeny of irradiated cells multiple generations after irradiation of parental cells. The phenotype is well established both in vivo (Morgan 2003) and in vitro (Morgan 2003), and may be critical in radiation carcinogenesis (Little 2000, Huang et al. 2003). Instability can be induced by both the deposition of energy in irradiated cells as well as by signals transmitted by irradiated (targeted) cells to non-irradiated (non-targeted) cells (Kadhim et al. 1992, Lorimore et al. 1998). Thus both targeted and non-targeted cells can pass on the legacy of radiation to their progeny. However the radiation induced events and cellular processes that respond to both targeted and non-targeted radiation effects that lead to the unstable phenotype remain elusive. The cell system we have used to study radiation induced genomic instability utilizes human hamster GM10115 cells. These cells have a single copy of human chromosome 4 in a background of hamster chromosomes. Instability is evaluated in the clonal progeny of irradiated cells and a clone is considered unstable if it contains three or more metaphase sub-populations involving unique rearrangements of the human chromosome (Marder and Morgan 1993). Many of these unstable clones have been maintained in culture for many years and have been extensively characterized. As initially described by Clutton et al., (Clutton et al. 1996) many of our unstable clones exhibit persistently elevated levels of reactive oxygen species (Limoli et al. 2003), which appear to be due dysfunctional mitochondria (Kim et al. 2006, Kim et al. 2006). Interestingly, but perhaps not surprisingly, our unstable clones do not demonstrate a “mutator phenotype” (Limoli et al. 1997), but they do continue to rearrange their genomes for many years. The limiting factor with this system is the target – the human chromosome. While some clones demonstrate amplification of this chromosome and thus lend

  18. Radiative-convective instability

    NASA Astrophysics Data System (ADS)

    Emanuel, Kerry; Wing, Allison A.; Vincent, Emmanuel M.

    2014-03-01

    equilibrium (RCE) is a simple paradigm for the statistical equilibrium the earth's climate would exhibit in the absence of lateral energy transport. It has generally been assumed that for a given solar forcing and long-lived greenhouse gas concentration, such a state would be unique, but recent work suggests that more than one stable equilibrium may be possible. Here we show that above a critical specified sea surface temperature, the ordinary RCE state becomes linearly unstable to large-scale overturning circulations. The instability migrates the RCE state toward one of the two stable equilibria first found by Raymond and Zeng (2000). It occurs when the clear-sky infrared opacity of the lower troposphere becomes so large, owing to high water vapor concentration, that variations of the radiative cooling of the lower troposphere are governed principally by variations in upper tropospheric water vapor. We show that the instability represents a subcritical bifurcation of the ordinary RCE state, leading to either a dry state with large-scale descent, or to a moist state with mean ascent; these states may be accessed by finite amplitude perturbations to ordinary RCE in the subcritical state, or spontaneously in the supercritical state. As first suggested by Raymond (2000) and Sobel et al. (2007), the latter corresponds to the phenomenon of self-aggregation of moist convection, taking the form of cloud clusters or tropical cyclones. We argue that the nonrobustness of self-aggregation in cloud system resolving models may be an artifact of running such models close to the critical temperature for instability.

  19. Chromosome instability syndromes

    SciTech Connect

    1993-12-31

    Chapter 11, discusses chromosome instability syndromes. The focus is on the most extensively studied genotypic chromosomal aberrations which include Bloom syndrome, Fanconi anemia, ataxia telangiectasia, and xeroderma pigmentosum. The great interest in these syndromes is out of proportion to their rare occurrence; however, studies of genotypic chromosome breakage have been inspired by the hope of throwing light on chromosome structure and behavior. A table is given which relates chromosomal aberrations in Bloom syndrome which may cause or promote cancer. 34 refs., 3 figs., 1 tab.

  20. Non-conventional Fishbone Instabilities

    SciTech Connect

    Ya.I. Kolesnichenko; V.V. Lutsenko; V.S. Marchenko; R.B. White

    2004-11-10

    New instabilities of fishbone type are predicted. First, a trapped-particle-induced m = n = 1 instability with the mode structure having nothing to do with the conventional rigid kink displacement. This instability takes place when the magnetic field is weak, so that the precession frequency of the energetic ions is not small as compared to the frequency of the corresponding Alfven continuum at r = 0 and the magnetic shear is small inside the q = 1 radius [the case relevant to spherical tori]. Second, an Energetic Particle Mode fishbone instability driven by circulating particles. Third, a double-kink-mode instability driven by the circulating energetic ions. In particular, the latter can have two frequencies simultaneously: we refer to it as ''doublet'' fishbones. This instability can occur when the radial profile of the energetic ions has an off-axis maximum inside the region of the mode localization.

  1. Failure of Anterior Cruciate Ligament Reconstruction

    PubMed Central

    Samitier, Gonzalo; Marcano, Alejandro I.; Alentorn-Geli, Eduard; Cugat, Ramon; Farmer, Kevin W; Moser, Michael W

    2015-01-01

    The present review classifies and describes the multifactorial causes of anterior cruciate ligament (ACL) surgery failure, concentrating on preventing and resolving such situations. The article particularly focuses on those causes that require ACL revision due to recurrent instability, without neglecting those that affect function or produce persistent pain. Although primary ACL reconstruction has satisfactory outcome rates as high as 97%, it is important to identify the causes of failure, because satisfactory outcomes in revision surgery can drop to as much as 76%. It is often possible to identify a primary or secondary cause of ACL surgery failure; even the most meticulous planning can give rise to unexpected findings during the intervention. The adopted protocol should therefore be sufficiently flexible to adapt to the course of surgery. Preoperative patient counseling is essential. The surgeon should limit the patient’s expectations for the outcome by explaining the complexity of this kind of procedure. With adequate preoperative planning, close attention to details and realistic patient expectations, ACL revision surgery may offer beneficial and satisfactory results for the patient. PMID:26550585

  2. Weibel instability with nonextensive distribution

    SciTech Connect

    Qiu, Hui-Bin; Liu, Shi-Bing

    2013-10-15

    Weibel instability in plasma, where the ion distribution is isotropic and the electron component of the plasma possesses the anisotropic temperature distribution, is investigated based on the kinetic theory in context of nonextensive statistics mechanics. The instability growth rate is shown to be dependent on the nonextensive parameters of both electron and ion, and in the extensive limit, the result in Maxwellian distribution plasma is recovered. The instability growth rate is found to be enhanced as the nonextensive parameter of electron increases.

  3. Artisan Aphakic Lens for Cataract Surgery in Anterior Megalophthalmos

    PubMed Central

    Galvis, Virgilio; Tello, Alejandro; Miotto, Giuseppe; Rangel, Carlos M.

    2012-01-01

    A 44-year-old man with anterior megalophthalmos arrived at the clinic presenting a cataract in the right eye. The corneal diameter was 13 mm. Iridodonesis and phacodonesis were evident during slit lamp examination. Anterior chamber depth was 5.89 mm, and the diameter of the capsular bag was approximately 14.45 mm. Due to the large capsular bag, a standard posterior chamber intraocular lens was considered inadequate because of potential instability. Phacoemulsification and an implantation of an iris-claw lens (Artisan for aphakia®, Ophtec) in the posterior chamber were performed with good results. In the fourth postoperative month, uncorrected distance visual acuity was 20/30, and 20/20 was achieved with +0.75 −1.25 × 10°. We consider retropupillary aphakic iris-claw intraocular lenses to be a worthwhile option in these cases of megalophthalmos and cataract, since instability is avoided and the procedure is less challenging than suturing the lens. PMID:23341820

  4. Study of cavitating inducer instabilities

    NASA Technical Reports Server (NTRS)

    Young, W. E.; Murphy, R.; Reddecliff, J. M.

    1972-01-01

    An analytic and experimental investigation into the causes and mechanisms of cavitating inducer instabilities was conducted. Hydrofoil cascade tests were performed, during which cavity sizes were measured. The measured data were used, along with inducer data and potential flow predictions, to refine an analysis for the prediction of inducer blade suction surface cavitation cavity volume. Cavity volume predictions were incorporated into a linearized system model, and instability predictions for an inducer water test loop were generated. Inducer tests were conducted and instability predictions correlated favorably with measured instability data.

  5. Instabilities in mimetic matter perturbations

    NASA Astrophysics Data System (ADS)

    Firouzjahi, Hassan; Gorji, Mohammad Ali; Mansoori, Seyed Ali Hosseini

    2017-07-01

    We study cosmological perturbations in mimetic matter scenario with a general higher derivative function. We calculate the quadratic action and show that both the kinetic term and the gradient term have the wrong sings. We perform the analysis in both comoving and Newtonian gauges and confirm that the Hamiltonians and the associated instabilities are consistent with each other in both gauges. The existence of instabilities is independent of the specific form of higher derivative function which generates gradients for mimetic field perturbations. It is verified that the ghost instability in mimetic perturbations is not associated with the higher derivative instabilities such as the Ostrogradsky ghost.

  6. Novel Cauchy-horizon instability

    SciTech Connect

    Maeda, Hideki; Torii, Takashi; Harada, Tomohiro

    2005-03-15

    The evolution of weak discontinuity is investigated on horizons in the n-dimensional static solutions in the Einstein-Maxwell-scalar-{lambda} system, including the Reissner-Nordstroem-(anti) de Sitter black hole. The analysis is essentially local and nonlinear. We find that the Cauchy horizon is unstable, whereas both the black hole event horizon and the cosmological event horizon are stable. This new instability, the so-called kink instability, of the Cauchy horizon is completely different from the well-known 'infinite-blueshift' instability. The kink instability makes the analytic continuation beyond the Cauchy horizon unstable.

  7. Anterior tibial plateau fracture: An often missed injury.

    PubMed

    Maheshwari, Jitendra; Pandey, Vinay Kumar; Mhaskar, Vikram Arun

    2014-09-01

    In most classifications of tibial plateau fractures, including one used most widely-Schatzker classification, fractures are described as a combination of medial and lateral condyle, primarily in the sagittal plane. Coronal component of these fractures, affecting the posterior tibial condyle is now well recognized. What is not described is anterior coronal component of the fracture, what we are calling "anterior tibial condyle fracture". These fractures are often missed on routine antero-posterior and lateral knee X-rays due to an overlap between the fracture and the normal bone. Eight cases of anterior tibial condyle fractures with posterior subluxation of the tibia, six of which were missed by the initial surgeon and two referred to us early, are described. Two of the six late cases and both the early ones were operated. Reconstruction of the anterior condyle and posterior cruciate ligament reconstruction was done. Primary outcome measures such as union of the fracture, residual flexion deformity, range of motion and stability were studied at the end of 6 months. All operated fractures united. There was no posterior sag in any. In those presenting late and were operated, the flexion deformity got corrected in all (average from 15° to 0°) and mean flexion achieved was 100° (range: 80-120°). In those presenting early and were operated, there was no flexion deformity at 6 months and a mean flexion achieved was 115° (range: 100-130°). None of the operated patients had instability. This article attempts to highlight that this injury is often missed. They should be suspected, diagnosed early and treated by reconstruction of anterior condyle, posterior cruciate ligament reconstruction.

  8. Anterior tibial plateau fracture: An often missed injury

    PubMed Central

    Maheshwari, Jitendra; Pandey, Vinay Kumar; Mhaskar, Vikram Arun

    2014-01-01

    Background: In most classifications of tibial plateau fractures, including one used most widely-Schatzker classification, fractures are described as a combination of medial and lateral condyle, primarily in the sagittal plane. Coronal component of these fractures, affecting the posterior tibial condyle is now well recognized. What is not described is anterior coronal component of the fracture, what we are calling “anterior tibial condyle fracture”. These fractures are often missed on routine antero-posterior and lateral knee X-rays due to an overlap between the fracture and the normal bone. Materials and Methods: Eight cases of anterior tibial condyle fractures with posterior subluxation of the tibia, six of which were missed by the initial surgeon and two referred to us early, are described. Two of the six late cases and both the early ones were operated. Reconstruction of the anterior condyle and posterior cruciate ligament reconstruction was done. Primary outcome measures such as union of the fracture, residual flexion deformity, range of motion and stability were studied at the end of 6 months. Results: All operated fractures united. There was no posterior sag in any. In those presenting late and were operated, the flexion deformity got corrected in all (average from 15° to 0°) and mean flexion achieved was 100° (range: 80-120°). In those presenting early and were operated, there was no flexion deformity at 6 months and a mean flexion achieved was 115° (range: 100-130°). None of the operated patients had instability. Conclusion: This article attempts to highlight that this injury is often missed. They should be suspected, diagnosed early and treated by reconstruction of anterior condyle, posterior cruciate ligament reconstruction. PMID:25298560

  9. PARTIAL TORUS INSTABILITY

    SciTech Connect

    Olmedo, Oscar; Zhang Jie

    2010-07-20

    Flux ropes are now generally accepted to be the magnetic configuration of coronal mass ejections (CMEs), which may be formed prior to or during solar eruptions. In this study, we model the flux rope as a current-carrying partial torus loop with its two footpoints anchored in the photosphere, and investigate its stability in the context of the torus instability (TI). Previous studies on TI have focused on the configuration of a circular torus and revealed the existence of a critical decay index of the overlying constraining magnetic field. Our study reveals that the critical index is a function of the fractional number of the partial torus, defined by the ratio between the arc length of the partial torus above the photosphere and the circumference of a circular torus of equal radius. We refer to this finding as the partial torus instability (PTI). It is found that a partial torus with a smaller fractional number has a smaller critical index, thus requiring a more gradually decreasing magnetic field to stabilize the flux rope. On the other hand, a partial torus with a larger fractional number has a larger critical index. In the limit of a circular torus when the fractional number approaches 1, the critical index goes to a maximum value. We demonstrate that the PTI helps us to understand the confinement, growth, and eventual eruption of a flux-rope CME.

  10. [Genomic instability in atherosclerosis].

    PubMed

    Dzhokhadze, T A; Buadze, T Zh; Gaiozishvili, M N; Kakauridze, N G; Lezhava, T A

    2014-11-01

    A comparative study of the level of genomic instability, parameters of quantitative and structural mutations of chromosomes (aberration, aneuploidy, polyploidy) in lymphocyte cultures from patients with atherosclerosis of age 80 years and older (control group - 30-35 years old) was conducted. The possibility of correction of disturbed genomic indicators by peptide bioregulators - Livagen (Lys-Glu-Asp-Ala) and cobalt ions with separate application or in combination was also studied. Control was lymphocyte culture of two healthy respective age groups. It was also shown that patients with atherosclerosis exhibit high level of genomic instability in all studied parameters, regardless of age, which may suggest that there is marked increase in chromatin condensation in atherosclerosis. It was also shown that Livagen (characterized by modifying influence on chromatin) separately and in combination with cobalt ions, promotes normalization of altered genomic indicators of atherosclerosis in both age groups. The results show that Livagen separately and in combination with cobalt ions has impact on chromatin of patients with atherosclerosis. The identified protective action of Livagen proves its efficacy in prevention of atherosclerosis.

  11. Microtearing instability in ITER*

    NASA Astrophysics Data System (ADS)

    Wong, King-Lap; Mikkelsen, David; Budny, Robert; Breslau, Joshua

    2010-11-01

    Microtearing modes are found to be unstable in some regions of a simulated ITER H-mode plasma [1] with the GS2 code [2]. Modes with kρs>1 are in the interior (r/a˜0.65-0.85) while longer wavelength modes are in the pedestal region. This instability may keep the pedestal within the peeling-ballooning stability boundary [3]. Microtearing modes can produce stochastic magnetic field similar to RMP coils; they may have similar effects on ELMs by increasing the pedestal width. The possibility of using this technique for ELM mitigation in ITER is explored. We propose to use a deuterium gas jet to control the microtearing instability and the Chirikov parameter at the edge. Preliminary evaluation of its effectiveness will be presented and the limitations of the GS2 code will be discussed based on our understanding from NSTX [4]. *This work is supported by USDoE contract DE-AC02-09CH11466. [4pt] [1] R. V. Budny, Nucl. Fusion (2009)[0pt] [2] W. Dorland et al., Phys. Rev. Lett. (2000).[0pt] [3] P. B. Snyder et al.,Nucl. Fusion (2009).[0pt] [4] K. L. Wong et al., Phys. Rev. Lett. (2007).

  12. Partial Torus Instability

    NASA Astrophysics Data System (ADS)

    Olmedo, Oscar; Zhang, Jie

    2010-07-01

    Flux ropes are now generally accepted to be the magnetic configuration of coronal mass ejections (CMEs), which may be formed prior to or during solar eruptions. In this study, we model the flux rope as a current-carrying partial torus loop with its two footpoints anchored in the photosphere, and investigate its stability in the context of the torus instability (TI). Previous studies on TI have focused on the configuration of a circular torus and revealed the existence of a critical decay index of the overlying constraining magnetic field. Our study reveals that the critical index is a function of the fractional number of the partial torus, defined by the ratio between the arc length of the partial torus above the photosphere and the circumference of a circular torus of equal radius. We refer to this finding as the partial torus instability (PTI). It is found that a partial torus with a smaller fractional number has a smaller critical index, thus requiring a more gradually decreasing magnetic field to stabilize the flux rope. On the other hand, a partial torus with a larger fractional number has a larger critical index. In the limit of a circular torus when the fractional number approaches 1, the critical index goes to a maximum value. We demonstrate that the PTI helps us to understand the confinement, growth, and eventual eruption of a flux-rope CME.

  13. Arthroscopic subscapularis bankart technique as a salvage procedure for failed anterior shoulder stabilization.

    PubMed

    Chaudhury, Salma; Delos, Demetris; Dines, Joshua S; Altchek, David W; Dodson, Christopher C; Newman, Ashley M; O'Brien, Stephen J

    2014-02-01

    Shoulder instability is a relatively common problem. Even with contemporary surgical techniques, instability can recur following both open and arthroscopic fixation. Surgical management of capsular insufficiency in anterior shoulder stabilization represents a significant challenge, particularly in young, active patients. There are a limited number of surgical treatment options. The Laterjet technique can present with a number of intraoperative challenges and postoperative complication. We report an arthroscopic subscapularis tenodesis technique as a salvage procedure for challenging glenohumeral instability cases. Sutures are passed through the subscapularis tendon and capsule before they are tied as one in the subdeltoid psace. The rotator interval is closed with superior and medial advancement of anterior and inferior tissue. This technical note carefully describes this procedure with useful technical tips, illustrations, and diagrams. Two clinical cases are described involving patients with recurrent instability following failed surgery who were successfully managed with this procedure. Both cases described resulted in improved shoulder stability, range of motion, and function following management with this surgical technique. This arthroscopic subscapularis tenodesis procedure is proposed as a useful alternative repair technique for cases of recurrent instability after failed surgery with isolated capsular insufficiency. It is believed that this arthroscopic subscapularis tenodesis technique can potentially provide similar outcomes to open bone block stabilization procedures, while reducing the risks associated with those procedures.

  14. Instability vaccination: A structural design to reduce Rayleigh Taylor instability

    NASA Astrophysics Data System (ADS)

    Esmaeili, Amin

    2013-10-01

    Instability vaccination can be defined as designing a structure to stimulate the system in order to develop immunity against its instability. In this work we have tried to do this stabilization by a new technique. Previously some suppression of R-M instability was done by insertion of magnetic field, but in this work we have tried to do this suppression by proposing a configuration similar to the shape of instability, we call it instability vaccination. This design will reduce the rotations (mostly rotations of Rayleigh Taylor instability) in the fluids that cause more mixing and instabilities. In this paper, we consider the evolution of the interface between two ideal semi-infinite fluid surfaces, using two-dimensional Riemann solver, to solve the Euler equations. First, we performed evolution of a rectangular disorder between the 2 surfaces using two-dimensional Riemann problem for the equations of Euler. Next, the interface was replaced with a perturbation that was part rectangular and part semi-circular (like a mushroom). The simulation was continued till some time steps using the HLL method. We have seen that the rotations of Rayleigh Taylor (R-T) instability were decreased in the second case. Email: amin@cavelab.cs.tsukuba.ac.jp

  15. Failure of osteointegration of hamstring tendon autograft after anterior cruciate ligament reconstruction.

    PubMed

    Song, Eun Kyoo; Rowe, Sung Man; Chung, Jae Yoon; Moon, Eun Sun; Lee, Keun Bae

    2004-04-01

    Anterior cruciate ligament (ACL) reconstruction is completed after implantation, when the graft material used undergoes extensive biologic remodelling and osteointegration. Failure of the osteointegration between the graft tendon and bone decreases the graft strength and induces anterior instability. We experienced 2 cases of failed osteointegration between tendon and bone after ACL reconstruction using 4 strands of the hamstring tendon. Surprisingly, osteointegration between the bone and tendon junction was not shown by intraoperative findings. The histologic findings also presented no evidence of osteointegration or biologic remodeling of the tendon. Two cases of failure of osteointegration are reported, with a review of the literature.

  16. Interobserver reproducibility of radiographic evaluation of lumbar spine instability

    PubMed Central

    Segundo, Saulo de Tarso de Sá Pereira; Valesin, Edgar Santiago; Lenza, Mario; Santos, Durval do Carmo Barros; Rosemberg, Laercio Alberto; Ferretti, Mario

    2016-01-01

    ABSTRACT Objective: To measure the interobserver reproducibility of the radiographic evaluation of lumbar spine instability. Methods: Measurements of the dynamic radiographs of the lumbar spine in lateral view were performed, evaluating the anterior translation and the angulation among the vertebral bodies. The tests were evaluated at workstations of the organization, through the Carestream Health Vue RIS (PACS), version 11.0.12.14 Inc. 2009© system. Results: Agreement in detecting cases of radiographic instability among the observers varied from 88.1 to 94.4%, and the agreement coefficients AC1 were all above 0.8, indicating excellent agreement. Conclusion: The interobserver analysis performed among orthopedic surgeons with different levels of training in dynamic radiographs of the spine obtained high reproducibility and agreement. However, some factors, such as the manual method of measurement and the presence of vertebral osteophytes, might have generated a few less accurate results in this comparative evaluation of measurements. PMID:27759827

  17. Preprosthetic movement of anterior teeth.

    PubMed

    Melsen, B

    1982-05-01

    Preprosthetic movement of anterior teeth is often performed on patients with missing anterior teeth, providing a better basis for subsequent bridgework. This can often be achieved by horizontal tooth movements of a tipping or translatory art whilst other patients present problems of a vertical nature with a deep overbite inconsistent with a healthy periodontal status. Intrusive tooth movements are needed as changes in facial height are not tolerated. The importance of understanding the biological basis for tooth movements in the planning of the biomechanics is stressed. Forces should be monitored according to the amount of general and local bone loss.

  18. The Rayleigh-Taylor instability

    NASA Astrophysics Data System (ADS)

    Piriz, A. R.; Cortázar, O. D.; López Cela, J. J.; Tahir, N. A.

    2006-12-01

    A new approach to the Rayleigh-Taylor instability is presented that yields exact solutions for the simplest cases and provides approximate but still very accurate analytical expressions for important and more complex cases involving nonideal fluids. The approach is based on Newton's second law and allows for an intuitive and physically appealing explanation of the mechanisms underlying the instability.

  19. Liquid propellant rocket combustion instability

    NASA Technical Reports Server (NTRS)

    Harrje, D. T.

    1972-01-01

    The solution of problems of combustion instability for more effective communication between the various workers in this field is considered. The extent of combustion instability problems in liquid propellant rocket engines and recommendations for their solution are discussed. The most significant developments, both theoretical and experimental, are presented, with emphasis on fundamental principles and relationships between alternative approaches.

  20. Bony instability of the shoulder.

    PubMed

    Bushnell, Brandon D; Creighton, R Alexander; Herring, Marion M

    2008-09-01

    Instability of the shoulder is a common problem treated by many orthopaedists. Instability can result from baseline intrinsic ligamentous laxity or a traumatic event-often a dislocation that injures the stabilizing structures of the glenohumeral joint. Many cases involve soft-tissue injury only and can be treated successfully with repair of the labrum and ligamentous tissues. Both open and arthroscopic approaches have been well described, with recent studies of arthroscopic soft-tissue techniques reporting results equal to those of the more traditional open techniques. Over the last decade, attention has focused on the concept of instability of the shoulder mediated by bony pathology such as a large bony Bankart lesion or an engaging Hill-Sachs lesion. Recent literature has identified unrecognized large bony lesions as a primary cause of failure of arthroscopic reconstruction for instability, a major cause of recurrent instability, and a difficult diagnosis to make. Thus, although such bony lesions may be relatively rare compared with soft-tissue pathology, they constitute a critically important entity in the management of shoulder instability. Smaller bony lesions may be amenable to arthroscopic treatment, but larger lesions often require open surgery to prevent recurrent instability. This article reviews recent developments in the diagnosis and treatment of bony instability.

  1. Research on aviation fuel instability

    NASA Technical Reports Server (NTRS)

    Baker, C. E.; Bittker, D. A.; Cohen, S. M.; Seng, G. T.

    1983-01-01

    The underlying causes of fuel thermal degradation are discussed. Topics covered include: nature of fuel instability and its temperature dependence, methods of measuring the instability, chemical mechanisms involved in deposit formation, and instrumental methods for characterizing fuel deposits. Finally, some preliminary thoughts on design approaches for minimizing the effects of lowered thermal stability are briefly discussed.

  2. Marital instability after midlife.

    PubMed

    Wu, Z; Penning, M J

    1997-09-01

    "Divorce in later life has been shown to produce dramatic declines in the economic, psychological, and physical well-being of marital partners. This study examines the prevalence and determinants of marital disruption after midlife using Becker's theory of marital instability. Using recent Canadian national data, the marital outcomes of women and men who were married as of age 40 are tracked across the remaining years of the marriage. Cox proportional hazard regression models indicate stabilizing effects of the duration of the marriage, the age at first marriage, the presence of young children, as well as of remarriage for middle-aged and older persons. Other significant risk factors include education, heterogamous marital status, premarital cohabitation, number of siblings, and region."

  3. [Treatment of patellar instability].

    PubMed

    Lind, Martin; Faunø, Peter; Sørensen, Ole Gade; Mygind-Klavsen, Bjarne

    2017-09-18

    First-time patellar luxation appears typically in teenagers and young adults below the age of 16 years, with a prevalence of 45/100,000/year. This luxation is treated with brief limited mobility in a bandage, and with a complementary physiotherapy if the mobility is influenced afterwards. Risk factors for patellar instability are patellofemoral dysplasia, hyperlaxity, patella alta and valgus malalignment in the knee joint. In case of repeated luxation the treatment is surgical, i.e. reconstruction of the medial patellofemoral ligament recreating the medial patella-stabilizing structures. If the dysplasia is severe, tuberositas tibiae-osteotomy and trochlea plastic can correct a lateral tracking of the knee joint. Generally, patella-stabilizing surgery is successful with a reluxation rate of only a few per cent.

  4. Instabilities in uranium plasma.

    NASA Technical Reports Server (NTRS)

    Tidman, D. A.

    1971-01-01

    The nonlinear evolution of unstable sound waves in a uranium plasma has been calculated using a multiple time-scale asymptotic expansion scheme. The fluid equations used include the fission power density, radiation diffusion, and the effects of the changing degree of ionization of the uranium atoms. The nonlinear growth of unstable waves is shown to be limited by mode coupling to shorter wavelength waves which are damped by radiation diffusion. This mechanism limits the wave pressure fluctuations to values of order delta P/P equal to about .00001 in the plasma of a typical gas-core nuclear rocket engine. The instability is thus not expected to present a control problem for this engine.

  5. Neurocardiovascular Instability and Cognition

    PubMed Central

    O’Callaghan, Susan; Kenny, Rose Anne

    2016-01-01

    Neurocardiovascular instability (NCVI) refers to abnormal neural control of the cardiovascular system affecting blood pressure and heart rate behavior. Autonomic dysfunction and impaired cerebral autoregulation in aging contribute to this phenomenon characterized by hypotension and bradyarrhythmia. Ultimately, this increases the risk of falls and syncope in older people. NCVI is common in patients with neurodegenerative disorders including dementia. This review discusses the various syndromes that characterize NCVI icluding hypotension, carotid sinus hypersensitivity, postprandial hypotension and vasovagal syncope and how they may contribute to the aetiology of cognitive decline. Conversely, they may also be a consequence of a common neurodegenerative process. Regardless, recognition of their association is paramount in optimizing management of these patients. PMID:27505017

  6. Instabilities in uranium plasma.

    NASA Technical Reports Server (NTRS)

    Tidman, D. A.

    1971-01-01

    The nonlinear evolution of unstable sound waves in a uranium plasma has been calculated using a multiple time-scale asymptotic expansion scheme. The fluid equations used include the fission power density, radiation diffusion, and the effects of the changing degree of ionization of the uranium atoms. The nonlinear growth of unstable waves is shown to be limited by mode coupling to shorter wavelength waves which are damped by radiation diffusion. This mechanism limits the wave pressure fluctuations to values of order delta P/P equal to about .00001 in the plasma of a typical gas-core nuclear rocket engine. The instability is thus not expected to present a control problem for this engine.

  7. Combustion Instabilities Modeled

    NASA Technical Reports Server (NTRS)

    Paxson, Daniel E.

    1999-01-01

    NASA Lewis Research Center's Advanced Controls and Dynamics Technology Branch is investigating active control strategies to mitigate or eliminate the combustion instabilities prevalent in lean-burning, low-emission combustors. These instabilities result from coupling between the heat-release mechanisms of the burning process and the acoustic flow field of the combustor. Control design and implementation require a simulation capability that is both fast and accurate. It must capture the essential physics of the system, yet be as simple as possible. A quasi-one-dimensional, computational fluid dynamics (CFD) based simulation has been developed which may meet these requirements. The Euler equations of mass, momentum, and energy have been used, along with a single reactive species transport equation to simulate coupled thermoacoustic oscillations. A very simple numerical integration scheme was chosen to reduce computing time. Robust boundary condition procedures were incorporated to simulate various flow conditions (e.g., valves, open ends, and choked inflow) as well as to accommodate flow reversals that may arise during large flow-field oscillations. The accompanying figure shows a sample simulation result. A combustor with an open inlet, a choked outlet, and a large constriction approximately two thirds of the way down the length is shown. The middle plot shows normalized, time-averaged distributions of the relevant flow quantities, and the bottom plot illustrates the acoustic mode shape of the resulting thermoacoustic oscillation. For this simulation, the limit cycle peak-to-peak pressure fluctuations were 13 percent of the mean. The simulation used 100 numerical cells. The total normalized simulation time was 50 units (approximately 15 oscillations), which took 26 sec on a Sun Ultra2.

  8. Internal rotor friction instability

    NASA Technical Reports Server (NTRS)

    Walton, J.; Artiles, A.; Lund, J.; Dill, J.; Zorzi, E.

    1990-01-01

    The analytical developments and experimental investigations performed in assessing the effect of internal friction on rotor systems dynamic performance are documented. Analytical component models for axial splines, Curvic splines, and interference fit joints commonly found in modern high speed turbomachinery were developed. Rotor systems operating above a bending critical speed were shown to exhibit unstable subsynchronous vibrations at the first natural frequency. The effect of speed, bearing stiffness, joint stiffness, external damping, torque, and coefficient of friction, was evaluated. Testing included material coefficient of friction evaluations, component joint quantity and form of damping determinations, and rotordynamic stability assessments. Under conditions similar to those in the SSME turbopumps, material interfaces experienced a coefficient of friction of approx. 0.2 for lubricated and 0.8 for unlubricated conditions. The damping observed in the component joints displayed nearly linear behavior with increasing amplitude. Thus, the measured damping, as a function of amplitude, is not represented by either linear or Coulomb friction damper models. Rotordynamic testing of an axial spline joint under 5000 in.-lb of static torque, demonstrated the presence of an extremely severe instability when the rotor was operated above its first flexible natural frequency. The presence of this instability was predicted by nonlinear rotordynamic time-transient analysis using the nonlinear component model developed under this program. Corresponding rotordynamic testing of a shaft with an interference fit joint demonstrated the presence of subsynchronous vibrations at the first natural frequency. While subsynchronous vibrations were observed, they were bounded and significantly lower in amplitude than the synchronous vibrations.

  9. Fingering instability of Bingham fluids

    NASA Astrophysics Data System (ADS)

    Ghadge, Shilpa; Myers, Tim

    2005-11-01

    Contact line instabilities have been extensively studied and many useful results obtained for industrial applications. Our research in this area is to explore these instabilities for non-Newtonian fluids which has wide scope in geological, biological as well as industrial areas. In this talk, we will present an analysis of fingering instability near a contact line of the thin sheet of fluid flowing down on a moderately inclined plane. This instability has been well studied for Newtonian fluids. We explore the effect of a yield strength of the fluid on this instability. We have conveniently assumed the presence of the precussor film of small thickness ahead of the fluid film to avoid some mathematical singularities. Using a lubrication-type approximation, we perform a linear stability analysis of a straight contact line. We will show comparison with some experimental results using suspensions of kaolin in silicone oil as a yield strength fluid.

  10. Gravitational Instabilities in Circumstellar Disks

    NASA Astrophysics Data System (ADS)

    Kratter, Kaitlin; Lodato, Giuseppe

    2016-09-01

    Star and planet formation are the complex outcomes of gravitational collapse and angular momentum transport mediated by protostellar and protoplanetary disks. In this review, we focus on the role of gravitational instability in this process. We begin with a brief overview of the observational evidence for massive disks that might be subject to gravitational instability and then highlight the diverse ways in which the instability manifests itself in protostellar and protoplanetary disks: the generation of spiral arms, small-scale turbulence-like density fluctuations, and fragmentation of the disk itself. We present the analytic theory that describes the linear growth phase of the instability supplemented with a survey of numerical simulations that aim to capture the nonlinear evolution. We emphasize the role of thermodynamics and large-scale infall in controlling the outcome of the instability. Despite apparent controversies in the literature, we show a remarkable level of agreement between analytic predictions and numerical results. In the next part of our review, we focus on the astrophysical consequences of the instability. We show that the disks most likely to be gravitationally unstable are young and relatively massive compared with their host star, Md/M*≥0.1. They will develop quasi-stable spiral arms that process infall from the background cloud. Although instability is less likely at later times, once infall becomes less important, the manifestations of the instability are more varied. In this regime, the disk thermodynamics, often regulated by stellar irradiation, dictates the development and evolution of the instability. In some cases the instability may lead to fragmentation into bound companions. These companions are more likely to be brown dwarfs or stars than planetary mass objects. Finally, we highlight open questions related to the development of a turbulent cascade in thin disks and the role of mode-mode coupling in setting the maximum angular

  11. Anterior cervical corpectomy and fusion for blastomycosis causing destruction of C6 vertebra: a case report.

    PubMed

    Patel, Kushal R; Szczodry, Michal; Neckrysh, Sergey; Siemionow, Krzysztof

    2015-11-25

    We describe a patient who had cervical spine osteomyelitis caused by Blastomyces dermatitidis that resulted in cord compression and cervical spine instability. A 25-year-old Hispanic woman presented with fever, sweats, neck pain, and an enlarging neck mass with purulent discharge after sustaining a C6 vertebral body fracture. Magnetic resonance imaging confirmed C6 vertebral osteomyelitis, demonstrated by vertebral body destruction, cervical spine instability, prevertebral abscess, and spinal cord compression. She underwent C6 anterior cervical corpectomy and fusion, with fungal cultures confirming Blastomyces dermatitidis. Anterior cervical corpectomy and fusion successful debrided, decompressed, and restored cervical spine stability in a patient with vertebral osteomyelitis caused by Blastomyces dermatitidis. The patient was subsequently treated with a 1-year course of itraconazole and had no recurrence of infection 4 years postoperatively.

  12. Anterior cruciate ligament - updating article.

    PubMed

    Luzo, Marcus Vinicius Malheiros; Franciozi, Carlos Eduardo da Silveira; Rezende, Fernando Cury; Gracitelli, Guilherme Conforto; Debieux, Pedro; Cohen, Moisés

    2016-01-01

    This updating article on the anterior cruciate ligament (ACL) has the aim of addressing some of the most interesting current topics in this field. Within this stratified approach, it contains the following sections: ACL remnant; anterolateral ligament and combined intra and extra-articular reconstruction; fixation devices; and ACL femoral tunnel creation techniques.

  13. Shoulder Bankart lesion with posterior instability: A case report of ultrasound detection.

    PubMed

    Arai, Ryuzo; Ito, Taisuke; Okudaira, Shuzo; Matsuda, Shuichi

    2017-08-01

    Minor instability of the shoulder has recently drawn attention as a cause of shoulder pain in athletes. However, it is difficult to correctly diagnose the direction in which the humeral head translates and subluxates, and to clarify the pathology of the instability. We present a case of a 20-year-old male with an unstable shoulder who could not raise his left arm due to pain. Since 6 years prior to the onset of pain, the patient could asymptomatically perform voluntary subluxation, but it was slight and the direction of the subluxation could not be confirmed. On physical examination, the conventional apprehension test and Castagna test were positive, but the jerk test was negative. Imaging studies including arthroscopy showed a Bankart lesion associated with anterior labrum detachment. There was no posterior Bankart lesion. Due to painful anterior shoulder instability, arthroscopic Bankart repair was successfully done; however, 9 months later the patient began experiencing symptomatic subluxation of the shoulder. At this time, the conventional apprehension test and Castagna test were both negative. It was difficult to detect the direction of the subluxation, just like in the preoperative condition. We performed an ultrasonographic examination from the posterior side; this clearly revealed the posterior subluxation mechanism as posterior slide of the humeral head and anterior shift of the glenoid. Based on these findings, we modified the rehabilitation and the subluxation resolved. This case suggests that ultrasound imaging can be an effective practical option for evaluating shoulder instability, especially in cases of slight posterior subluxation.

  14. Does surgery for instability of the shoulder truly stabilize the glenohumeral joint?

    PubMed Central

    Lädermann, Alexandre; Denard, Patrick J.; Tirefort, Jérôme; Kolo, Frank C.; Chagué, Sylvain; Cunningham, Grégory; Charbonnier, Caecilia

    2016-01-01

    Abstract Despite the fact that surgery is commonly used to treat glenohumeral instability, there is no evidence that such treatment effectively corrects glenohumeral translation. The purpose of this prospective clinical study was to analyze the effect of surgical stabilization on glenohumeral translation. Glenohumeral translation was assessed in 11 patients preoperatively and 1 year postoperatively following surgical stabilization for anterior shoulder instability. Translation was measured using optical motion capture and computed tomography. Preoperatively, anterior translation of the affected shoulder was bigger in comparison to the normal contralateral side. Differences were significant for flexion and abduction movements (P < 0.001). Postoperatively, no patients demonstrated apprehension and all functional scores were improved. Despite absence of apprehension, postoperative anterior translation for the surgically stabilized shoulders was not significantly different from the preoperative values. While surgical treatment for anterior instability limits the chance of dislocation, it does not seem to restore glenohumeral translation during functional range of motion. Such persistent microinstability may explain residual pain, apprehension, inability to return to activity and even emergence of dislocation arthropathy that is seen in some patients. Further research is necessary to better understand the causes, effects, and treatment of residual microinstability following surgical stabilization of the shoulder. PMID:27495043

  15. Temperature anisotropy and beam type whistler instabilities

    NASA Technical Reports Server (NTRS)

    Hashimoto, K.; Matsumoto, H.

    1976-01-01

    Whistler instabilities have been investigated for two different types; i.e., a temperature-anisotropy type instability and a beam-type instability. A comparison between the two types of whistler instabilities is made within the framework of linear theory. A transition from one type to the other is also discussed, which is an extension of the work on electrostatic beam and Landau instabilities performed by O'Neil and Malmberg (1968) for electromagnetic whistler instabilities. It is clarified that the essential source of the whistler instability is not beam kinetic energy but a temperature anisotropy, even for the beam-type whistler instability.

  16. The Effect of Subcritical Bone Loss and Exposure on Recurrent Instability After Arthroscopic Bankart Repair in Intercollegiate American Football.

    PubMed

    Dickens, Jonathan F; Owens, Brett D; Cameron, Kenneth L; DeBerardino, Thomas M; Masini, Brendan D; Peck, Karen Y; Svoboda, Steven J

    2017-07-01

    There is no consensus on the optimal method of stabilization (arthroscopic or open) in collision athletes with anterior shoulder instability. To examine the effect of "subcritical" bone loss and football-specific exposure on the rate of recurrent shoulder instability after arthroscopic stabilization in an intercollegiate American football population. Case-control study; Level of evidence, 3. Fifty intercollegiate football players underwent primary arthroscopic stabilization for anterior shoulder instability and returned to football for at least a single season. Preoperatively, 32 patients experienced recurrent subluxations, and 18 patients experienced a single or recurrent dislocation. Shoulders with glenoid bone loss >20%, an engaging Hill-Sachs lesion, an off-track lesion, and concomitant rotator cuff repair were excluded from the study. The primary outcome of interest was the ability to return to football without subsequent instability. Patients were followed for time to a subsequent instability event after return to play using days of exposure to football and total follow-up time after arthroscopic stabilization. Fifty consecutive patients returned to American football for a mean 1.5 seasons (range, 1-3) after arthroscopic stabilization. Three of 50 (6%; 95% CI, 1.3%-16.5%) patients experienced recurrent instability. There were no subsequent instability events after a mean 3.2 years of military service. All shoulders with glenoid bone loss >13.5% (n = 3) that underwent arthroscopic stabilization experienced recurrent instability upon returning to sport, while none of the shoulders with <13.5% glenoid bone loss (n = 47) sustained a recurrent instability event during football ( X(2) = 15.80, P < .001). Shoulders with >13.5% glenoid bone loss had an incidence rate of 5.31 cases of recurrent instability per 1000 athlete-exposures of football. In 72,000 athlete-exposures to football with <13.5% glenoid bone loss, there was no recurrent instability. Significantly

  17. ROTATIONAL INSTABILITIES AND CENTRIFUGAL HANGUP

    SciTech Connect

    K. NEW; J. CENTRELLA

    2000-12-01

    One interesting class of gravitational radiation sources includes rapidly rotating astrophysical objects that encounter dynamical instabilities. We have carried out a set of simulations of rotationally induced instabilities in differentially rotating polytropes. An n=1.5 polytrope with the Maclaurin rotation law will encounter the m=2 bar instability at T/{vert_bar}W{vert_bar} {ge} 0.27. Our results indicate that the remnant of this in-stability is a persistent bar-like structure that emits a long-lived gravitational radiation signal. Furthermore, dynamical instability is shown to occur in n=3.33 polytropes with the j-constant rotation law at T/{vert_bar}W{vert_bar} {ge} 0:14. In this case, the dominant mode of instability is m=1. Such instability may allow a centrifugally-hung core to begin collapsing to neutron star densities on a dynamical timescale. If it occurs in a supermassive star, it may produce gravitational radiation detectable by LISA.

  18. Analysis of structures causing instabilities.

    PubMed

    Wilhelm, Thomas

    2007-07-01

    We present a simple new method to systematically identify all topological structures (e.g., positive feedback loops) potentially leading to locally unstable steady states: ICSA-The instability causing structure analysis. Systems without any instability causing structure (i.e., not fulfilling the necessary topological condition for instabilities) cannot have unstable steady states. It follows that common bistability or multistability and Hopf bifurcations are excluded and sustained oscillations and deterministic chaos are most unlikely. The ICSA leads to new insights into the topological organization of chemical and biochemical systems, such as metabolic, gene regulatory, and signal transduction networks.

  19. Simulations of Astrophysical fluid instabilities

    NASA Astrophysics Data System (ADS)

    Calder, A. C.; Fryxell, B.; Rosner, R.; Dursi, L. J.; Olson, K.; Ricker, P. M.; Timmes, F. X.; Zingale, M.; MacNeice, P.; Tufo, H. M.

    2001-10-01

    We present direct numerical simulations of mixing at Rayleigh-Taylor unstable interfaces performed with the FLASH code, developed at the ASCI/Alliances Center for Astrophysical Thermonuclear Flashes at the University of Chicago. We present initial results of single-mode studies in two and three dimensions. Our results indicate that three-dimensional instabilities grow significantly faster than two-dimensional instabilities and that grid resolution can have a significant effect on instability growth rates. We also find that unphysical diffusive mixing occurs at the fluid interface, particularly in poorly resolved simulations. .

  20. Instability of a bubble chain.

    PubMed

    Zhang, Wenjuan; An, Yu

    2013-05-01

    Based on the theory of shape instability and diffusive instability for single bubbles, we have studied the instability of an individual bubble in a bubble chain and found that its stable area enlarges the narrower the distance between bubbles. The spatial stability of the bubble chain is due to the secondary Bjerknes force between bubbles. Numerical calculations show the tension of the bubble chain varies with bubble distance and maxima appear at certain distances which could correspond to the stable states of the bubble chain.

  1. Phase Instability in Semiconductor Lasers

    NASA Astrophysics Data System (ADS)

    Gil, L.; Lippi, G. L.

    2014-11-01

    For many years, the apparent absence of a phase instability has characterized lasers as peculiar nonlinear oscillators. We show that this unusual feature is solely due to the approximations used in writing the standard models. A new, careful derivation of the fundamental equations, based on codimension 2 bifurcation theory, shows the possible existence of dynamical regimes displaying either a pure phase instability, or mixed phase-amplitude turbulence. A comparison to existing experimental results convincingly shows that the Benjamin-Feir instability, common to all nonlinear wave problems, is a fundamental, satisfactory interpretation for their deterministic multimode dynamics.

  2. Revision anterior cruciate ligament surgery: experience from Miami.

    PubMed

    Uribe, J W; Hechtman, K S; Zvijac, J E; Tjin-A-Tsoi, E W

    1996-04-01

    Failed anterior cruciate ligament reconstruction as defined by recurrent patholaxity is increasingly commonplace. This report presents the findings of 54 patients who had unsuccessful intraarticular anterior cruciate ligament reconstruction to correct persistent instability and who subsequently underwent revision anterior cruciate ligament surgery. Before revision, patients were evaluated by clinical examination, KT-1000 arthrometer, radiographs, Lysholm knee score, Tegner activity scale, and subjective questionnaire. The results were compared at a mean of 32 months following revision surgery. There was an average of 16 months from index procedure to the time of revision. Autogenous patellar tendon grafts were used in 61% of the cases with 30% of these harvested from the contralateral knee. Fresh frozen patellar tendon was used in 35% and autogenous hamstring tendons in 4%. Revision was successful in objectively improving stability in all patients with an average KT-000 of 2.8 mm. Autogenous tissue grafts provided greater objective stability when compared with allograft tissue with average KT-1000 of 2.2 and 3.3, respectively. Functionally, however, there was no significant difference in outcome between the 2 groups. Harvesting of the contralateral patellar tendon was found to have no adverse long term effect. Subjectively, the results were significantly worse depending on the degree of articular cartilage degeneration. Only 54% of patients returned to their preanterior cruciate ligament injury activity level. Competence in various anterior cruciate ligament reconstruction techniques will facilitate revision surgery especially in avoiding preexisting tunnels and hardware. Correct graft placement and addressing the secondary restraints are critical to successful revision surgery.

  3. Chronic ankle instability.

    PubMed

    Gerstner Garces, Juan Bernardo

    2012-09-01

    Chronic instability of the ankle and anterolateral impingement syndrome are abnormalities that present as a result of inversion and forced plantar-flexion traumas of the foot, despite strict conservative management in the ER and in rehabilitation. A conservative approach is always the first choice of treatment, including anti-inflammatory medications, rehabilitation and proprioception, infiltration with steroids in impingement cases, and use of orthotics, whose true effectiveness is the subject of multiple studies and much debate. Good to excellent results can be obtained surgically with a minimally invasive approach, such as the arthroscopic technique presented herein. Such an approach is useful in managing a combination of conditions such as anterolateral impingement, synovitis, and osteochondral lesions of the talus. The method is easily reproducible, its learning curve is rapid, and it has the advantage of not preventing the use other arthroscopic methods, or open anatomic or nonanatomic methods (tendon transfers), in the case of failure. No nerve lesion was recorded, probably owing to the use of the security zone, and neither was there any arthrofibrosis, possibly related to the use of nonsteroidal anti-inflammatory medications in the immediate postsurgical period coupled with aggressive rehabilitation from the fourth week. The success of the technique is due to multidisciplinary team work leading to the ultimate achievement of patient satisfaction. This technique is not indicated for patients with a high sports demand or for sport professionals, until further biomechanical studies on its use and success are completed. Copyright © 2012 Elsevier Inc. All rights reserved.

  4. Resistive instabilities in tokamaks

    SciTech Connect

    Rutherford, P.H.

    1985-10-01

    Low-m tearing modes constitute the dominant instability problem in present-day tokamaks. In this lecture, the stability criteria for representative current profiles with q(0)-values slightly less than unit are reviewed; ''sawtooth'' reconnection to q(0)-values just at, or slightly exceeding, unity is generally destabilizing to the m = 2, n = 1 and m = 3, n = 2 modes, and severely limits the range of stable profile shapes. Feedback stabilization of m greater than or equal to 2 modes by rf heating or current drive, applied locally at the magnetic islands, appears feasible; feedback by island current drive is much more efficient, in terms of the radio-frequency power required, then feedback by island heating. Feedback stabilization of the m = 1 mode - although yielding particularly beneficial effects for resistive-tearing and high-beta stability by allowing q(0)-values substantially below unity - is more problematical, unless the m = 1 ideal-MHD mode can be made positively stable by strong triangular shaping of the central flux surfaces. Feedback techniques require a detectable, rotating MHD-like signal; the slowing of mode rotation - or the excitation of non-rotating modes - by an imperfectly conducting wall is also discussed.

  5. Instabilities of Charged Polyampholytes

    NASA Astrophysics Data System (ADS)

    Kardar, Mehran

    1996-03-01

    We consider polymers formed from a (quenched) random sequence of charged monomers of opposite signs. Such polymers, known as polyampholytes (PAs), are compact when completely neutral and expanded when highly charged.footnote Y. Kantor and M. Kardar, Europhys. Lett. 27, 643 (1994). We examine the transition between the two regimes by Monte Carlo simulations, exact enumeration studies, and by analogies to charged drops. We find that the overall excess charge, Q, is the main determinant of the size of the PA. A polymer composed of N charges of ± q0 is compact for Qinstability of a charged drop. A uniform excess charge causes the breakup of a fluid drop. We speculate that a uniformly charged polymer stretches out to a necklace shape. The inhomogeneities in charge distort the shape away from an ordered necklace.footnote Y. Kantor and M. Kardar, Phys. Rev. E 51, 1299 (1995).

  6. Instabilities in the aether

    SciTech Connect

    Carroll, Sean M.; Dulaney, Timothy R.; Gresham, Moira I.; Tam, Heywood

    2009-03-15

    We investigate the stability of theories in which Lorentz invariance is spontaneously broken by fixed-norm vector 'aether' fields. Models with generic kinetic terms are plagued either by ghosts or by tachyons, and are therefore physically unacceptable. There are precisely three kinetic terms that are not manifestly unstable: a sigma model ({partial_derivative}{sub {mu}}A{sub {nu}}){sup 2}, the Maxwell Lagrangian F{sub {mu}}{sub {nu}}F{sup {mu}}{sup {nu}}, and a scalar Lagrangian ({partial_derivative}{sub {mu}}A{sup {mu}}){sup 2}. The timelike sigma-model case is well defined and stable when the vector norm is fixed by a constraint; however, when it is determined by minimizing a potential there is necessarily a tachyonic ghost, and therefore an instability. In the Maxwell and scalar cases, the Hamiltonian is unbounded below, but at the level of perturbation theory there are fewer degrees of freedom and the models are stable. However, in these two theories there are obstacles to smooth evolution for certain choices of initial data.

  7. Evaporative instabilities in climbing films

    NASA Astrophysics Data System (ADS)

    Hosoi, A. E.; Bush, John W. M.

    2001-09-01

    We consider flow in a thin film generated by partially submerging an inclined rigid plate in a reservoir of ethanol or methanol water solution and wetting its surface. Evaporation leads to concentration and surface tension gradients that drive flow up the plate. An experimental study indicates that the climbing film is subject to two distinct instabilities. The first is a convective instability characterized by flattened convection rolls aligned in the direction of flow and accompanied by free-surface deformations; in the meniscus region, this instability gives rise to pronounced ridge structures aligned with the mean flow. The second instability, evident when the plate is nearly vertical, takes the form of transverse surface waves propagating up the plate.

  8. Kinetic theory of Jeans instability.

    PubMed

    Trigger, S A; Ershkovich, A I; van Heijst, G J F; Schram, P P J M

    2004-06-01

    Kinetic treatment of the Jeans gravitational instability, with collisions taken into account, is presented. The initial-value problem for the distribution function which obeys the kinetic equation, with the collision integral conserving the number of particles, is solved. Dispersion relation is obtained and analyzed. New modes are found. Collisions are shown not to affect the Jeans instability criterion. Although the instability growth rate diminishes, the collisions they cannot quench the instability. However, the oscillation spectrum is modified significantly: even in the neighborhood of the threshold frequency omega=0 (separating stable and unstable modes) the spectrum of oscillations can strongly depend on the collision frequency. Propagating (rather than aperiodic) modes are also found. These modes, however, are strongly damped.

  9. Fluid Instabilities inside Astrophysical Explosions

    NASA Astrophysics Data System (ADS)

    Chen, Ke-Jung; Woosley, Stan; Heger, Alexander; Almgren, Ann; Zheng, Weiqun

    2014-11-01

    We present our results from the simulations of fluid instabilities inside supernovae with a new radiation-hydrodynamic code, CASTRO. Massive stars are ten times more massive than Sun. Observational and theoretical studies suggest that these massive stars tend to end their lives with energetic explosions, so-called supernovae. Many fluid instabilities occur during the supernova explosions. The fluid instabilities can be driven by hydrodynamics, nuclear burning, or radiation. In this talk, we discuss about the possible physics of fluid instabilities found in our simulations and how the resulting mixing affects the observational signatures of supernovae. This work was supported by the DOE HEP Program under contract DE-SC0010676; the National Science Foundation (AST 0909129) and the NASA Theory Program (NNX14AH34G).

  10. Clustering instability of focused swimmers

    NASA Astrophysics Data System (ADS)

    Lauga, Eric; Nadal, Francois

    2016-12-01

    One of the hallmarks of active matter is its rich nonlinear dynamics and instabilities. Recent numerical simulations of phototactic algae showed that a thin jet of swimmers, obtained from hydrodynamic focusing inside a Poiseuille flow, was unstable to longitudinal perturbations with swimmers dynamically clustering (Jibuti L. et al., Phys. Rev. E, 90, (2014) 063019). As a simple starting point to understand these instabilities, we consider in this paper an initially homogeneous one-dimensional line of aligned swimmers moving along the same direction, and characterise its instability using both a continuum framework and a discrete approach. In both cases, we show that hydrodynamic interactions between the swimmers lead to instabilities in density for which we compute the growth rate analytically. Lines of pusher-type swimmers are predicted to remain stable while lines of pullers (such as flagellated algae) are predicted to always be unstable.

  11. Longer reaction time of the fibularis longus muscle and reduced postural control in basketball players with functional ankle instability: A pilot study.

    PubMed

    Méndez-Rebolledo, Guillermo; Guzmán-Muñoz, Eduardo; Gatica-Rojas, Valeska; Zbinden-Foncea, Hermann

    2015-08-01

    Motor control evaluation in subjects with functional ankle instability is questionable when both ankles of the same subject are compared (affected vs non-affected). To compare the postural control and reaction time of ankle muscles among: basketball players with FAI (instability group), basketball players without FAI (non-instability group) and healthy non-basketball-playing participants (control group). Case-control study. Laboratory. Instability (n = 10), non-instability (n = 10), and control groups (n = 11). Centre of pressure variables (area, velocity and sway) were measured with a force platform. Reaction time of ankle muscles was measured via electromyography. A one-way ANOVA demonstrated that there were significant differences between the instability and non-instability groups in the fibularis longus (p < 0.001), fibularis brevis (p = 0.031) and tibialis anterior (p = 0.049) muscles. Repeated-measures ANOVA and post hoc analysis determined significant differences for the area between the instability and non-instability groups (p = 0.001). Basketball players with FAI have reduced postural control and longer reaction time of the fibularis and tibialis anterior muscles. Copyright © 2014 Elsevier Ltd. All rights reserved.

  12. The results of Bankart repair without capsular plication in patients with recurrent traumatic anterior shoulder dislocation.

    PubMed

    Kalkar, İsmail; Esenyel, Cem Zeki; Saygılı, Mehmet Selçuk; Esenyel, Ayşın; Gürbüz, Hakan

    2017-01-01

    The aim of this study was to evaluate the results of patients with recurrent anterior shoulder dislocation, who had been treated with repair of the Bankart lesion without capsuler plication. The study included 22 shoulders of 22 patients (16 males and 6 females) with a mean age of 28 years, who underwent Bankart repair between 2011 and 2014. Patients with bilateral shoulder instability, multiple instability, >25% glenoid bone loss, and those with a history of shoulder surgery were not included in the study. The average follow-up time was 21.2 months. Evaluation was made of the preoperative number of dislocations, postoperative recurrence, functional status, and daily activity performance of the patients. Shoulder range of motion was measured. The results were evaluated using the Rowe shoulder score and the Oxford shoulder instability score. Recurrence was observed in only one patient who had a shoulder dislocation after trauma, thus giving a recurrence rate of 4.5%. Shoulder range of motion was full in all except that one patient. The mean Rowe shoulder score was 95.5 (excellent) and Oxford shoulder stability score was 44.6 (excellent). No recurrent shoulder dislocation was observed in patients who underwent Bankart repair surgery. Plication was not performed with the Bankart repair. Close to full range of motion was obtained in all patients. In conclusion, Bankart repair alone can be considered to be sufficient for the treatment of traumatic recurrent anterior shoulder instability.

  13. Extradural anterior clinoidectomy. Technical note.

    PubMed

    Noguchi, Akio; Balasingam, Vijayabalan; Shiokawa, Yoshiaki; McMenomey, Sean O; Delashaw, Johnny B

    2005-05-01

    The anterior clinoid process (ACP), located on the skull base, is a relatively small structure, although its removal provides enormous gain in facilitating the management of lesions--either tumors or aneurysms--in the paraclinoid region and upper basilar artery. The extensive surgical field gained contributes to safer exposure of the neurovascular elements in the vicinity while avoiding excessive and hazardous retraction of the brain. In this report the authors present a technically simpler avenue for performing an extradural anterior clinoidectomy after reviewing the anatomy of the ACP and its anatomical variations. Additionally, the original Dolenc procedure and its subseqtient derivatives are compared and contrasted to the authors' simpler and less laborious technique. Different clinical situations in which to use the procedure are described based on the authors' experience from 60 cases (40 aneurysm cases and 20 tumor cases) during a 4-year period.

  14. 38 CFR 3.379 - Anterior poliomyelitis.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 38 Pensions, Bonuses, and Veterans' Relief 1 2010-07-01 2010-07-01 false Anterior poliomyelitis. 3... Specific Diseases § 3.379 Anterior poliomyelitis. If the first manifestations of acute anterior poliomyelitis present themselves in a veteran within 35 days of termination of active military service, it...

  15. 38 CFR 3.379 - Anterior poliomyelitis.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 38 Pensions, Bonuses, and Veterans' Relief 1 2013-07-01 2013-07-01 false Anterior poliomyelitis. 3... Specific Diseases § 3.379 Anterior poliomyelitis. If the first manifestations of acute anterior poliomyelitis present themselves in a veteran within 35 days of termination of active military service, it is...

  16. 38 CFR 3.379 - Anterior poliomyelitis.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 38 Pensions, Bonuses, and Veterans' Relief 1 2014-07-01 2014-07-01 false Anterior poliomyelitis. 3... Specific Diseases § 3.379 Anterior poliomyelitis. If the first manifestations of acute anterior poliomyelitis present themselves in a veteran within 35 days of termination of active military service, it is...

  17. 38 CFR 3.379 - Anterior poliomyelitis.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 38 Pensions, Bonuses, and Veterans' Relief 1 2012-07-01 2012-07-01 false Anterior poliomyelitis. 3... Specific Diseases § 3.379 Anterior poliomyelitis. If the first manifestations of acute anterior poliomyelitis present themselves in a veteran within 35 days of termination of active military service, it is...

  18. 38 CFR 3.379 - Anterior poliomyelitis.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 38 Pensions, Bonuses, and Veterans' Relief 1 2011-07-01 2011-07-01 false Anterior poliomyelitis. 3... Specific Diseases § 3.379 Anterior poliomyelitis. If the first manifestations of acute anterior poliomyelitis present themselves in a veteran within 35 days of termination of active military service, it is...

  19. Traumatic anterior shoulder dislocation: a case study of nonoperative management in a mixed martial arts athlete

    PubMed Central

    Sims, Kevin; Spina, Andreo

    2009-01-01

    Objective: To present an evidence-informed approach to the nonoperative management of a first-time, traumatic anterior shoulder dislocation. Clinical Features: A 30-year-old mixed martial arts athlete, with no prior shoulder injuries, presented one day following a first-time, traumatic anterior shoulder dislocation. An eight-week, individualized, intensive, nonoperative rehabilitation program was immediately begun upon presentation. Intervention and Outcome: Management consisted of immobilization of the shoulder in external rotation and a progressive rehabilitation program aimed at restoring range of motion, strength of the dynamic stabilizers, and proprioception of the shoulder. Eight weeks post-dislocation the patient had regained full range of motion and strength compared to the unaffected limb and apprehension and relocation tests for instability were negative. Conclusion: This case illustrates successful management of a first-time, traumatic, anterior shoulder dislocation using immobilization in external rotation combined with an intensive rehabilitation program. PMID:20037691

  20. Simple arthroscopic partial meniscectomy associated with anterior cruciate-deficient knees.

    PubMed

    Marshall, S; Levas, M G; Harrah, A

    1985-01-01

    Twenty-five patients with combined tears of the meniscus and anterior cruciate ligament in the same knee were evaluated for the results of a simple arthroscopic meniscectomy that preserved the meniscal rim. These patients, classified as "recreational athletes," were analyzed to determine their postoperative functional capabilities. Using the presence or absence of the pivot shift sign as the most important indicator of functional capability, we found that partial meniscectomy was effective in allowing patients to regain a high degree of normal functional ability and in permitting forward motion activities. However, all patients were left with an anterior cruciate-deficient knee that caused laxity in the anterior plane and frequently in the rotatory plane. Rotatory laxity markedly limits activities, and those patients unable to adjust to their instability are considering further surgery.

  1. Nontraumatic glenohumeral instability and coracoacromial impingement in swimmers.

    PubMed

    Bak, K

    1996-06-01

    Competitive swimming is one of the most demanding and time-consuming sports. Swimmers at elite level practice 20-30 h per week. During 1 year's practice, the average top level swimmer performs more than 500,000 stroke revolutions per arm. These innumerable repetitions over many years of hard training together with an increasing muscular imbalance around the shoulder girdle seem to be the main etiological factors in the development of the over-use syndrome swimmer's shoulder. Shoulder pain in swimmers has in general been regarded as synonymous with coracoacromial impingement, i.e. anterior shoulder pain due to rotator cuff tendinitis, but new knowledge suggests that a concomitant glenohumeral instability plays an additional role. The diagnostic complexity of the problem is as challenging as the search for the gold standard of treatment. The condition should ideally be diagnosed as early as possible, and intensive functional rehabilitation of the shoulder girdle including the scapular muscles should be started in order to restore muscle balance. The surgical possibilities include subacromial decompression in cases of purely mechanical impingement. If a painful glenohumeral instability persists after intensive functional rehabilitation, anterior capsulolabral reconstruction can be performed. Still, however, short- and long-term results show that surgery is less successful in elite athletes involved in overhead sports. Prevention protocols include education of coaches in primary injury prophylaxis and the institution of resistance strength training in prepubescent swimmers. Emphasis should be made to improve muscular balance around the glenohumeral and scapulothoracic joints.

  2. Fluctuating Asymmetry and Developmental Instability in Sagittal Craniosynostosis

    PubMed Central

    DeLeon, Valerie Burke; Richtsmeier, Joan T.

    2010-01-01

    Objective: To determine whether premature sagittal craniosynostosis is associated with developmental instability in the skull by analyzing fluctuating asymmetry in skull shape. Design: Cranial shape was quantified by collecting coordinate data from landmarks located on three-dimensional reconstructions of preoperative computed tomography (CT) images of 22 children with sagittal craniosynostosis and 22 age-matched controls. A fluctuating asymmetry application of Euclidean distance matrix analysis (EDMA) was used to quantify and compare asymmetry in cranial shape using these landmark data. Results: In contrast to expectations, the sagittal craniosynostosis group did not show a statistically significant increase in the overall level of fluctuating asymmetry relative to the control group. However, we discerned statistically significant localized increases in fluctuating asymmetry in the sagittal craniosynostosis group at pterion and the anterior clinoid processes (α = .05). We also determined a significant correlation of fluctuating asymmetry values between the two groups (r = .71). Conclusions: We conclude that there is no evidence of a role for system-wide developmental instability in the etiology of nonsyndromic sagittal craniosynostosis. However, the localized evidence of asymmetry at the anterior clinoid processes in the sagittal synostosis group suggests an association with the tracts of dura mater that attach there. PMID:19254065

  3. Instability following total knee arthroplasty.

    PubMed

    Rodriguez-Merchan, E Carlos

    2011-10-01

    Background Knee prosthesis instability (KPI) is a frequent cause of failure of total knee arthroplasty. Moreover, the degree of constraint required to achieve immediate and long-term stability in total knee arthroplasty (TKA) is frequently debated. Questions This review aims to define the problem, analyze risk factors, and review strategies for prevention and treatment of KPI. Methods A PubMed (MEDLINE) search of the years 2000 to 2010 was performed using two key words: TKA and instability. One hundred and sixty-five initial articles were identified. The most important (17) articles as judged by the author were selected for this review. The main criteria for selection were that the articles addressed and provided solutions to the diagnosis and treatment of KPI. Results Patient-related risk factors predisposing to post-operative instability include deformity requiring a large surgical correction and aggressive ligament release, general or regional neuromuscular pathology, and hip or foot deformities. KPI can be prevented in most cases with appropriate selection of implants and good surgical technique. When ligament instability is anticipated post-operatively, the need for implants with a greater degree of constraint should be anticipated. In patients without significant varus or valgus malalignment and without significant flexion contracture, the posterior cruciate ligament (PCL) can be retained. However, the PCL should be sacrificed when deformity exists particularly in patients with rheumatoid arthritis, previous patellectomy, previous high tibial osteotomy or distal femoral osteotomy, and posttraumatic osteoarthritis with disruption of the PCL. In most cases, KPI requires revision surgery. Successful outcomes can only be obtained if the cause of KPI is identified and addressed. Conclusions Instability following TKA is a common cause of the need for revision. Typically, knees with deformity, rheumatoid arthritis, previous patellectomy or high tibial osteotomy, and

  4. Aerodynamic instability: A case history

    NASA Technical Reports Server (NTRS)

    Eisenmann, R. C.

    1985-01-01

    The identification, diagnosis, and final correction of complex machinery malfunctions typically require the correlation of many parameters such as mechanical construction, process influence, maintenance history, and vibration response characteristics. The progression is reviewed of field testing, diagnosis, and final correction of a specific machinery instability problem. The case history presented addresses a unique low frequency instability problem on a high pressure barrel compressor. The malfunction was eventually diagnosed as a fluidic mechanism that manifested as an aerodynamic disturbance to the rotor assembly.

  5. Magnetothermal instability in cooling flows

    NASA Technical Reports Server (NTRS)

    Loewenstein, Michael

    1990-01-01

    The effect of magnetic fields on thermal instability in cooling flows is investigated using linear, Eulerian perturbation analysis. As contrasted with the zero magnetic-field case, hydromagnetic stresses support perturbations against acceleration caused by buoyancy - comoving evolution results and global growth rates are straightforward to obtain for a given cooling flow entropy distribution. In addition, background and induced magnetic fields ensure that conductive damping of thermal instability is greatly reduced.

  6. Waves and instabilities in plasmas

    SciTech Connect

    Chen, L.

    1987-01-01

    The contents of this book are: Plasma as a Dielectric Medium; Nyquist Technique; Absolute and Convective Instabilities; Landau Damping and Phase Mixing; Particle Trapping and Breakdown of Linear Theory; Solution of Viasov Equation via Guilding-Center Transformation; Kinetic Theory of Magnetohydrodynamic Waves; Geometric Optics; Wave-Kinetic Equation; Cutoff and Resonance; Resonant Absorption; Mode Conversion; Gyrokinetic Equation; Drift Waves; Quasi-Linear Theory; Ponderomotive Force; Parametric Instabilities; Problem Sets for Homework, Midterm and Final Examinations.

  7. Magnetothermal instability in cooling flows

    NASA Technical Reports Server (NTRS)

    Loewenstein, Michael

    1990-01-01

    The effect of magnetic fields on thermal instability in cooling flows is investigated using linear, Eulerian perturbation analysis. As contrasted with the zero magnetic-field case, hydromagnetic stresses support perturbations against acceleration caused by buoyancy - comoving evolution results and global growth rates are straightforward to obtain for a given cooling flow entropy distribution. In addition, background and induced magnetic fields ensure that conductive damping of thermal instability is greatly reduced.

  8. Material Instabilities in Particulate Systems

    NASA Technical Reports Server (NTRS)

    Goddard, J. D.

    1999-01-01

    Following is a brief summary of a theoretical investigation of material (or constitutive) instability associated with shear induced particle migration in dense particulate suspensions or granular media. It is shown that one can obtain a fairly general linear-stability analysis, including the effects of shear-induced anisotropy in the base flow as well as Reynolds dilatancy. A criterion is presented here for simple shearing instability in the absence of inertia and dilatancy.

  9. Instability of enclosed horizons

    NASA Astrophysics Data System (ADS)

    Kay, Bernard S.

    2015-03-01

    We point out that there are solutions to the scalar wave equation on dimensional Minkowski space with finite energy tails which, if they reflect off a uniformly accelerated mirror due to (say) Dirichlet boundary conditions on it, develop an infinite stress-energy tensor on the mirror's Rindler horizon. We also show that, in the presence of an image mirror in the opposite Rindler wedge, suitable compactly supported arbitrarily small initial data on a suitable initial surface will develop an arbitrarily large stress-energy scalar near where the two horizons cross. Also, while there is a regular Hartle-Hawking-Israel-like state for the quantum theory between these two mirrors, there are coherent states built on it for which there are similar singularities in the expectation value of the renormalized stress-energy tensor. We conjecture that in other situations with analogous enclosed horizons such as a (maximally extended) Schwarzschild black hole in equilibrium in a (stationary spherical) box or the (maximally extended) Schwarzschild-AdS spacetime, there will be similar stress-energy singularities and almost-singularities—leading to instability of the horizons when gravity is switched on and matter and gravity perturbations are allowed for. All this suggests it is incorrect to picture a black hole in equilibrium in a box or a Schwarzschild-AdS black hole as extending beyond the past and future horizons of a single Schwarzschild (/Schwarzschild-AdS) wedge. It would thus provide new evidence for 't Hooft's brick wall model while seeming to invalidate the picture in Maldacena's ` Eternal black holes in AdS'. It would thereby also support the validity of the author's matter-gravity entanglement hypothesis and of the paper ` Brick walls and AdS/CFT' by the author and Ortíz.

  10. Production of anterior segment ischemia.

    PubMed Central

    Hiatt, R L

    1977-01-01

    Anterior segment ischemic changes can occur without detachment of any muscles. The most common cause of such ischemic changes of the anterior segment is the removal of too many rectus muscles in one operation. Twenty dog eyes and eight monkey eyes were subjected to the disinsertion and detachment of various combinations of extraocular muscles. The dogs were sacrificed at intervals from 30 to 90 days. During the observation period, they were observed for gross and slit-lamp changes. The enucleated eyes were studied microscopically for signs of ischemic and necrotic changes. Two patients who were studied, observed, and treated for anterior segment ischemia following muscle surgery are described. The changes which occur after extraocular muscle surgery are extensive and include corneal edema, cataract, chemosis, corneal changes, decreases in intraocular pressure, decreases in outflow or glaucoma, and frank necrosis. The variables which lead to this reaction are described in detail. Also, some unanswered queries, such as the duration of the reaction and the time interval of the reaction after multiple muscle operations are discussed. Images FIGURE 1 A FIGURE 1 B FIGURE 1 C FIGURE 2 A FIGURE 2 B FIGURE 2 C FIGURE 2 D FIGURE 3 FIGURE 4 PMID:418549

  11. Erectile function after anterior urethroplasty.

    PubMed

    Coursey, J W; Morey, A F; McAninch, J W; Summerton, D J; Secrest, C; White, P; Miller, K; Pieczonka, C; Hochberg, D; Armenakas, N

    2001-12-01

    We ascertained the impact of anterior urethroplasty on male sexual function. A validated questionnaire was mailed to 200 men who underwent anterior urethroplasty to evaluate postoperative sexual function. Questions addressed the change in erect penile length and angle, patient satisfaction with erection, preoperative and postoperative coital frequency, and change in erection noted by the sexual partner. Results were stratified by the urethral reconstruction method, namely anastomosis, buccal mucosal graft, penile flap and all others, and compared with those in a similar group of men who underwent circumcision only. Of the 200 men who underwent urethroplasty 152 who were 17 to 83 years old (mean age 45.7) completed the questionnaire. Average followup was 36 months (range 3 to 149). Overall there was a similar incidence of sexual problems after urethroplasty and circumcision. Penile skin flap urethroplasty was associated with a slightly higher incidence of impaired sexual function than other procedures (p >0.05). Men with a longer stricture were most likely to report major changes in erectile function and penile length (p <0.05) but improvement was evident with time in 61.8%. Overall anterior urethral reconstruction appears no more likely to cause long-term postoperative sexual dysfunction than circumcision. Men with a long stricture may be at increased risk for transient erectile changes.

  12. Vertical Instability at IPNS RCS.

    SciTech Connect

    Wang, S.; Brumwell, F. R.; Dooling, J. C.; Harkay, K. C.; Kustom, R.; McMichael, G. E.; Middendorf, M. E.; Nassiri, A.; Accelerator Systems Division

    2008-01-01

    The rapid cycling synchrotron (RCS) of the intense pulsed neutron source (IPNS) at ANL accelerates > 3.0 times 10{sup 12} protons from 50 MeV to 450 MeV with 30-Hz repetition frequency. During the acceleration cycle, the rf frequency varies from 2.21 MHz to 5.14 MHz. Presently, the beam current is limited by a vertical instability. By analyzing turn-by-turn beam position monitor (BPM) data, large- amplitude mode 0 and mode 1 vertical beam centroid oscillations were observed in the later part of the acceleration cycle. The oscillations start in the tail of the bunch, build up, and remain localized in the tail half of the bunch. This vertical instability was compared with a head-tail instability that was intentionally induced in the RCS by adjusting the trim sextupoles. It appears that our vertical instability is not a classical head-tail instability [1]. More data analysis and experiments were performed to characterize the instability.

  13. Vector-Resonance-Multimode Instability

    NASA Astrophysics Data System (ADS)

    Sergeyev, S. V.; Kbashi, H.; Tarasov, N.; Loiko, Yu.; Kolpakov, S. A.

    2017-01-01

    The modulation and multimode instabilities are the main mechanisms which drive spontaneous spatial and temporal pattern formation in a vast number of nonlinear systems ranging from biology to laser physics. Using an Er-doped fiber laser as a test bed, here for the first time we demonstrate both experimentally and theoretically a new type of a low-threshold vector-resonance-multimode instability which inherits features of multimode and modulation instabilities. The same as for the multimode instability, a large number of longitudinal modes can be excited without mode synchronization. To enable modulation instability, we modulate the state of polarization of the lasing signal with the period of the beat length by an adjustment of the in-cavity birefringence and the state of polarization of the pump wave. As a result, we show the regime's tunability from complex oscillatory to periodic with longitudinal mode synchronization in the case of resonance matching between the beat and cavity lengths. Apart from the interest in laser physics for unlocking the tunability and stability of dynamic regimes, the proposed mechanism of the vector-resonance-multimode instability can be of fundamental interest for the nonlinear dynamics of various distributed systems.

  14. Translation of the glenohumeral joint in patients with multidirectional and posterior instability: awake examination versus examination under anesthesia.

    PubMed

    Yoldas, E A; Faber, K J; Hawkins, R J

    2001-01-01

    The purpose of this study was to assist in establishing guidelines to determine the degree of shoulder instability, the value of awake clinical examination, and the value of examination under anesthesia (EUA). Forty-three patients with clinical diagnosis of multidirectional shoulder instability (MDI) and 28 patients with posterior instability underwent bilateral shoulder translation testing, both awake and while under anesthesia. Two surgeons using guidelines and translation grades developed by the American Shoulder and Elbow Surgeons examined each patient and assigned a single grade for the anterior, posterior, and inferior directions. A comparison of translational grade was performed with the use of Pearson chi2 and McNemar symmetry to determine association. The patients with MDI showed increased translation in the anterior, inferior, and posterior directions when the affected limb was compared with the noninvolved side in both preoperative examination and EUA. Furthermore, the patients with MDI showed increased anterior translation on the affected side during EUA compared with the clinical examination. Patients with posterior instability demonstrated increased anterior translation for both affected and noninvolved limbs during EUA. However, the posterior translation obtained before surgery did not change during EUA for both the affected and noninvolved limbs, and there was no side-to-side difference in posterior translation.

  15. Libration-driven multipolar instabilities

    NASA Astrophysics Data System (ADS)

    Cébron, D.; Vantieghem, S.; Herreman, W.

    2014-01-01

    We consider rotating flows in non-axisymmetric enclosures that are driven by libration, i.e. by a small periodic modulation of the rotation rate. Thanks to its simplicity, this model is relevant to various contexts, from industrial containers (with small oscillations of the rotation rate) to fluid layers of terrestial planets (with length-of-day variations). Assuming a multipolar $n$-fold boundary deformation, we first obtain the two-dimensional basic flow. We then perform a short-wavelength local stability analysis of the basic flow, showing that an instability may occur in three dimensions. We christen it the Libration Driven Multipolar Instability (LDMI). The growth rates of the LDMI are computed by a Floquet analysis in a systematic way, and compared to analytical expressions obtained by perturbation methods. We then focus on the simplest geometry allowing the LDMI, a librating deformed cylinder. To take into account viscous and confinement effects, we perform a global stability analysis, which shows that the LDMI results from a parametric resonance of inertial modes. Performing numerical simulations of this librating cylinder, we confirm that the basic flow is indeed established and report the first numerical evidence of the LDMI. Numerical results, in excellent agreement with the stability results, are used to explore the non-linear regime of the instability (amplitude and viscous dissipation of the driven flow). We finally provide an example of LDMI in a deformed spherical container to show that the instability mechanism is generic. Our results show that the previously studied libration driven elliptical instability simply corresponds to the particular case $n=2$ of a wider class of instabilities. Summarizing, this work shows that any oscillating non-axisymmetric container in rotation may excite intermittent, space-filling LDMI flows, and this instability should thus be easy to observe experimentally.

  16. Prevention and management of post-instability glenohumeral arthropathy

    PubMed Central

    Waterman, Brian R; Kilcoyne, Kelly G; Parada, Stephen A; Eichinger, Josef K

    2017-01-01

    Post-instability arthropathy may commonly develop in high-risk patients with a history of recurrent glenohumeral instability, both with and without surgical stabilization. Classically related to anterior shoulder instability, the incidence and rates of arthritic progression may vary widely. Radiographic arthritic changes may be present in up to two-thirds of patients after primary Bankart repair and 30% after Latarjet procedure, with increasing rates associated with recurrent dislocation history, prominent implant position, non-anatomic reconstruction, and/or lateralized bone graft placement. However, the presence radiographic arthrosis does not predict poor patient-reported function. After exhausting conservative measures, both joint-preserving and arthroplasty surgical options may be considered depending on a combination of patient-specific and anatomic factors. Arthroscopic procedures are optimally indicated for individuals with focal disease and may yield superior symptomatic relief when combined with treatment of combined shoulder pathology. For more advanced secondary arthropathy, total shoulder arthroplasty remains the most reliable option, although the clinical outcomes, wear characteristics, and implant survivorship remains a concern among active, young patients. PMID:28361016

  17. Prevention and management of post-instability glenohumeral arthropathy.

    PubMed

    Waterman, Brian R; Kilcoyne, Kelly G; Parada, Stephen A; Eichinger, Josef K

    2017-03-18

    Post-instability arthropathy may commonly develop in high-risk patients with a history of recurrent glenohumeral instability, both with and without surgical stabilization. Classically related to anterior shoulder instability, the incidence and rates of arthritic progression may vary widely. Radiographic arthritic changes may be present in up to two-thirds of patients after primary Bankart repair and 30% after Latarjet procedure, with increasing rates associated with recurrent dislocation history, prominent implant position, non-anatomic reconstruction, and/or lateralized bone graft placement. However, the presence radiographic arthrosis does not predict poor patient-reported function. After exhausting conservative measures, both joint-preserving and arthroplasty surgical options may be considered depending on a combination of patient-specific and anatomic factors. Arthroscopic procedures are optimally indicated for individuals with focal disease and may yield superior symptomatic relief when combined with treatment of combined shoulder pathology. For more advanced secondary arthropathy, total shoulder arthroplasty remains the most reliable option, although the clinical outcomes, wear characteristics, and implant survivorship remains a concern among active, young patients.

  18. Interfacial Instabilities on a Droplet

    NASA Astrophysics Data System (ADS)

    Jalaal, Maziyar; Mehravaran, Kian

    2013-11-01

    The fragmentation of droplets is an essential stage of several natural and industrial applications such as fuel atomization and rain phenomena. In spite of its relatively long history, the mechanism of fragmentation is not clear yet. This is mainly due to small length and time scales as well as the non-linearity of the process. In the present study, two and three-dimensional numerical simulations have been performed to understand the early stages of the fragmentation of an initially spherical droplet. Simulations are performed for high Reynolds and a range of relatively high Weber numbers (shear breakup). To resolve the small-scale instabilities generated over the droplet, a second-order adaptive finite volume/volume of fluids (FV/VOF) method is employed, where the grid resolution is increased with the curvature of the gas-liquid interface as well as the vorticity magnitude. The study is focused on the onset and growth of interfacial instabilities. The role of Kelvin-Helmholtz instability (in surface wave formation) and Rayleigh-Taylor instability (in azimuthal transverse modulation) are shown and the obtained results are compared with the linear instability theories for zero and non-zero vorticity layers. Moreover, the analogy between the fragmentation of a single drop and a co-axial liquid jet is discussed. The current results can be used for the further development of the current secondary atomization models.

  19. EXPLOSIVE INSTABILITY AND CORONAL HEATING

    SciTech Connect

    Dahlburg, R. B.; Liu, J.-H.; Klimchuk, J. A.; Nigro, G.

    2009-10-20

    The observed energy-loss rate from the solar corona implies that the coronal magnetic field has a critical angle at which energy is released. It has been hypothesized that at this critical angle an 'explosive instability' would occur, leading to an enhanced conversion of magnetic energy into heat. In earlier investigations, we have shown that a shear-dependent magnetohydrodynamic process called 'secondary instability' has many of the distinctive features of the hypothetical 'explosive instability'. In this paper, we give the first demonstration that this 'secondary instability' occurs in a system with line-tied magnetic fields and boundary shearing-basically the situation described by Parker. We also show that, as the disturbance due to secondary instability attains finite amplitude, there is a transition to turbulence which leads to enhanced dissipation of magnetic and kinetic energy. These results are obtained from numerical simulations performed with a new parallelized, viscoresistive, three-dimensional code that solves the cold plasma equations. The code employs a Fourier collocation-finite difference spatial discretization, and uses a third-order Runge-Kutta temporal discretization.

  20. Kozai-Lidov disc instability

    NASA Astrophysics Data System (ADS)

    Lubow, Stephen H.; Ogilvie, Gordon I.

    2017-08-01

    Recent results by Martin et al. showed in 3D smoothed particle hydrodynamics simulations that tilted discs in binary systems can be unstable to the development of global, damped Kozai-Lidov (KL) oscillations in which the discs exchange tilt for eccentricity. We investigate the linear stability of KL modes for tilted inviscid discs under the approximations that the disc eccentricity is small and the disc remains flat. By using 1D equations, we are able to probe regimes of large ratios of outer to inner disc edge radii that are realistic for binary systems of hundreds of astronomical unit separations and are not easily probed by multidimensional simulations. For order unity binary mass ratios, KL instability is possible for a window of disc aspect ratios H/r in the outer parts of a disc that roughly scale as (nb/n)2 ≲ H/r ≲ nb/n, for binary orbital frequency nb and orbital frequency n at the disc outer edge. We present a framework for understanding the zones of instability based on the determination of branches of marginally unstable modes. In general, multiple growing eccentric KL modes can be present in a disc. Coplanar apsidal-nodal precession resonances delineate instability branches. We determine the range of tilt angles for unstable modes as a function of disc aspect ratio. Unlike the KL instability for free particles that involves a critical (minimum) tilt angle, disc instability is possible for any non-zero tilt angle depending on the disc aspect ratio.

  1. The Effect of Modified Brostrom-Gould Repair for Lateral Ankle Instability on In Vivo Tibiotalar Kinematics

    PubMed Central

    Wainright, William B; Spritzer, Charles E.; Lee, Jun Young; Easley, Mark E.; DeOrio, James K.; Nunley, James A.; DeFrate, Louis E.

    2012-01-01

    Background Lateral ankle instability leads to an increased risk of tibiotalar joint osteoarthritis. Previous studies have found abnormal tibiotalar joint motions with lateral ankle instability that may contribute to this increased incidence of osteoarthritis, including increased anterior translation and internal rotation of the talus under weight-bearing loading. Surgical repairs for lateral ankle instability have shown good clinical results, but the effects of repair on in vivo ankle motion are not well understood. Hypothesis The modified Broström-Gould lateral ligament reconstruction decreases anterior translation and internal rotation of the talus under in vivo weight-bearing loading conditions. Study Design Controlled laboratory study. Methods Seven patients underwent modified Brostöm-Gould repair for unilateral lateral ankle instability. Ankle joint kinematics as a function of increasing body weight were studied with magnetic resonance imaging and biplanar fluoroscopy. Tibiotalar kinematics were measured in unstable ankles preoperatively and postoperatively at a mean follow-up of 12 months, as well as in the uninjured contralateral ankles of the same individuals. Results Surgical repair resulted in statistically significant decreases in anterior translation of the talus (0.9±0.3mm, p=0.018) at 100% bodyweight and internal rotation of the talus at 75% (2.6±0.8°, p=0.019) and 100% (2.7±0.8°, p=0.013) bodyweight compared to ankle kinematics measured before repair. No statistically significant differences were detected between repaired ankles and contralateral normal ankles. Conclusion The modified Broström-Gould repair improved the abnormal joint motion observed in patients with lateral ankle instability, decreasing anterior translation and internal rotation of the talus. Clinical Relevance Altered kinematics may contribute to the tibiotalar joint degeneration that occurs with chronic lateral ankle instability. The findings of the current study support

  2. Partial tearing of the anterior cruciate ligament: diagnosis and treatment.

    PubMed

    Temponi, Eduardo Frois; de Carvalho Júnior, Lúcio Honório; Sonnery-Cottet, Bertrand; Chambat, Pierre

    2015-01-01

    Partial tears of the anterior cruciate ligament (ACL) are common and represent 10-27% of the total. The main reasons for attending to cases of non-torn bundles are biomechanical, vascular and proprioceptive. Continued presence of the bundle also serves as protection during the healing process. There is controversy regarding the definition of these injuries, which is based on anatomy, clinical examination, translation measurements, imaging examinations and arthroscopy. The way in which it is treated will depend on the existing laxity and instability. Conservative treatment is optional for cases without instability, with a focus on motor rehabilitation. Surgical treatment is a challenge, since it requires correct positioning of the bone tunnels and conservation of the remnants of the torn bundle. The pivot shift test under anesthesia, the magnetic resonance findings, the previous level and type of sports activity and the arthroscopic appearance and mechanical properties of the remnants will aid the orthopedist in the decision-making process between conservative treatment, surgical treatment with strengthening of the native ACL (selective reconstruction) and classical (anatomical) reconstruction.

  3. Partial tearing of the anterior cruciate ligament: diagnosis and treatment

    PubMed Central

    Temponi, Eduardo Frois; de Carvalho Júnior, Lúcio Honório; Sonnery-Cottet, Bertrand; Chambat, Pierre

    2015-01-01

    Partial tears of the anterior cruciate ligament (ACL) are common and represent 10–27% of the total. The main reasons for attending to cases of non-torn bundles are biomechanical, vascular and proprioceptive. Continued presence of the bundle also serves as protection during the healing process. There is controversy regarding the definition of these injuries, which is based on anatomy, clinical examination, translation measurements, imaging examinations and arthroscopy. The way in which it is treated will depend on the existing laxity and instability. Conservative treatment is optional for cases without instability, with a focus on motor rehabilitation. Surgical treatment is a challenge, since it requires correct positioning of the bone tunnels and conservation of the remnants of the torn bundle. The pivot shift test under anesthesia, the magnetic resonance findings, the previous level and type of sports activity and the arthroscopic appearance and mechanical properties of the remnants will aid the orthopedist in the decision-making process between conservative treatment, surgical treatment with strengthening of the native ACL (selective reconstruction) and classical (anatomical) reconstruction. PMID:26229890

  4. Value of ultrasonography for detecting ligament damage in athletes with chronic ankle instability compared to computed arthrotomography.

    PubMed

    Guillodo, Yannick; Varache, Sophie; Saraux, Alain

    2010-12-01

    Ankle sprains may be followed by chronic pain and/or instability, which may induce substantial disability, most notably in athletes. Chronic ankle instability promotes the development of cartilage lesions in athletes. Therefore, accurate evaluation of the ankle ligaments is crucial to the optimal management of chronic ankle instability after a sprain. The objective of this study was to assess the performance of ultrasonography in assessing damage to the anterior talofibular ligament (ATFL) in athletes with chronic ankle instability after a sprain. Consecutive patients seen at the author's clinic for ankle instability more than 3 months after a sprain underwent ultrasonography and computed arthrotomography after a clinical anterior drawer stress test. Cohen's kappa was computed to evaluate agreement between the 2 imaging modalities. This study included 56 patients, 46 men and 10 women, aged 15 to 69 years (mean, 30.1 ± 10.6 years). Mean time from the sprain to imaging was 7.6 ± 4.02 months. ATFL damage was found by ultrasonography in 34 (61%) of 56 patients and by computed arthrotomography in 39 of 55 patients (71%; κ = 0.76). Cartilage damage was visualized by computed arthrotomography in 14 (25%) patients, all of whom had ATFL damage. Agreement was substantial (κ = 0.76) between ultrasonography and computed arthrotomography for assessing the ATFL. The data support the use of ultra-sonography as the second-line investigation after a standard radiographic assessment in athletes with chronic ankle instability after a sprain.

  5. Instability of EDS maglev systems

    SciTech Connect

    Cai, Y.; Chen, S.S.

    1993-09-01

    Instabilities of an EDS maglev suspension system with 3 D.O.F. and 5 D.O.F. vehicles traveling on a double L-shaped set of guideway conductors have been investigated with various experimentally measured magnetical force data incorporated into the theoretical models. Divergence and flutter are obtained from both analytical and numerical solutions for coupled vibration of the 3 D.O.F. maglev vehicle model. Instabilities of five direction motions (heave, slip, rill, pitch and yaw) are observed for the 4 D.O.F. vehicle model. It demonstrates that system parameters, such as, system damping, vehicle geometry and coupling effects among five different motions play very important roles in the occurrence of dynamic instabilities of maglev vehicles.

  6. Thermocapillary instabilities with gravity modulation

    NASA Astrophysics Data System (ADS)

    Zebib, Abdelfattah

    2002-11-01

    We study vibrational thermocapillary instabilities in an infinite layer with one bounding surface rigid, the other free and nondeformable, and both adiabatic. A constant temperature gradient imposed on the free surface drives a return flow, and a zero-mean harmonic gravitational acceleration is assumed to model g-jitter. Linear stability of the time-periodic base state is determined by calculating the Floquet exponents in the parameter space of: the Marangoni number Ma, Rayleigh number Ra, dimensionless frequency Ω, Prandtl number Pr, and wavenumbers α and β. The stability boundaries are composed of two intersecting branches emanating from the points of pure thermocapilary or buoyant instabilities as was found in the 2D study β=0 by Suresh & Homsy (Phys. Fluids 2001). However, 3D instabilities continue to dominate as was found by Smith & Davis (JFM 1983) with Ra=0. We also find that the region of stablity grows with increasing Ω.

  7. Compressive Instability Phenomena During Springback

    NASA Astrophysics Data System (ADS)

    Kim, J.-B.; Yoon, J. W.; Yang, D. Y.

    2007-05-01

    Springback in sheet metal product makes difficulties in die design because small strain causes large displacement. Especially for the sheet metal product having small geometric constraints, springback displacement may become severe. After first stage of stamping of outer case of washing machine, a large amount of springback is observed. The stamping depth of the outer case is small while stamping area is very large compared to the stamping depth, and therefore, there exists small geometric constraints in the formed part. Also, a compressive instability during the elastic recovery takes place and this instability enlarged the elastic recovery and dimensional error. In this paper, the compressive instability during the elastic recovery is analyzed using bifurcation theory. The final deformed shape after springback is obtained by bifurcating the solution path from primary to secondary. The deformed shapes obtained by the finite element analysis are in good agreement with the experimental data. The bifurcation behavior and the springback displacement for different forming depth are investigated.

  8. Compressive Instability Phenomena During Springback

    SciTech Connect

    Kim, J.-B.; Yoon, J. W.; Yang, D. Y.

    2007-05-17

    Springback in sheet metal product makes difficulties in die design because small strain causes large displacement. Especially for the sheet metal product having small geometric constraints, springback displacement may become severe. After first stage of stamping of outer case of washing machine, a large amount of springback is observed. The stamping depth of the outer case is small while stamping area is very large compared to the stamping depth, and therefore, there exists small geometric constraints in the formed part. Also, a compressive instability during the elastic recovery takes place and this instability enlarged the elastic recovery and dimensional error. In this paper, the compressive instability during the elastic recovery is analyzed using bifurcation theory. The final deformed shape after springback is obtained by bifurcating the solution path from primary to secondary. The deformed shapes obtained by the finite element analysis are in good agreement with the experimental data. The bifurcation behavior and the springback displacement for different forming depth are investigated.

  9. Hydrodynamick instabilities on ICF capsules

    SciTech Connect

    Haan, S.W.

    1991-06-07

    This article summarizes our current understanding of hydrodynamic instabilities as relevant to ICF. First we discuss classical, single mode Rayleigh-Taylor instability, and nonlinear effects in the evolution of a single mode. Then we discuss multimode systems, considering: (1) the onset of nonlinearity; (2) a second order mode coupling theory for weakly nonlinear effects, and (3) the fully nonlinear regime. Two stabilization mechanisms relevant to ICF are described next: gradient scale length and convective stabilization. Then we describe a model which is meant to estimate the weakly nonlinear evolution of multi-mode systems as relevant to ICF, given the short-wavelength stabilization. Finally, we discuss the relevant code simulation capability, and experiments. At this time we are quite optimistic about our ability to estimate instability growth on ICF capsules, but further experiments and simulations are needed to verify the modeling. 52 refs.

  10. Gravitational instabilities in protostellar disks

    NASA Technical Reports Server (NTRS)

    Tohline, J. E.

    1994-01-01

    The nonaxisymmetric stability of self-gravitating, geometrically thick accretion disks has been studied for protostellar systems having a wide range of disk-to-central object mass ratios. Global eigenmodes with four distinctly different characters were identified using numerical, nonlinear hydrodynamic techniques. The mode that appears most likely to arise in normal star formation settings, however, resembles the 'eccentric instability' that was identified earlier in thin, nearly Keplerian disks: It presents an open, one-armed spiral pattern that sweeps continuously in a trailing direction through more than 2-pi radians, smoothly connecting the inner and outer edges of the disk, and requires cooperative motion of the point mass for effective amplification. This particular instability promotes the development of a single, self-gravitating clump of material in orbit about the point mass, so its routine appearance in our simulations supports the conjecture that the eccentric instability provides a primary route to the formation of short-period binaries in protostellar systems.

  11. Chondral Injury in Patellofemoral Instability

    PubMed Central

    Lustig, Sébastien; Servien, Elvire; Neyret, Philippe

    2014-01-01

    Objective: Patellofemoral instability is common and affects a predominantly young age group. Chondral injury occurs in up to 95%, and includes osteochondral fractures and loose bodies acutely and secondary degenerative changes in recurrent cases. Biomechanical abnormalities, such as trochlear dysplasia, patella alta, and increased tibial tuberosity-trochlear groove distance, predispose to both recurrent dislocations and patellofemoral arthrosis. Design: In this article, we review the mechanisms of chondral injury in patellofemoral instability, diagnostic modalities, the distribution of lesions seen in acute and episodic dislocation, and treatments for articular cartilage lesions of the patellofemoral joint. Results: Little specific evidence exists for cartilage treatments in patellofemoral instability. In general, the results of reparative and restorative procedures in the patellofemoral joint are inferior to those observed in other compartments of the knee. Conclusion: Given the increased severity of chondral lesions and progression to osteoarthritis seen with recurrent dislocations, careful consideration should be given to early stabilisation in patients with predisposing factors. PMID:26069693

  12. Faraday instability in deformable domains

    NASA Astrophysics Data System (ADS)

    Pucci, Giuseppe; Ben Amar, Martine; Couder, Yves

    2014-11-01

    We investigate the Faraday instability in floating liquid lenses, as an example of hydrodynamic instability that develops in a domain with flexible boundaries. We show that a mutual adaptation of the instability pattern and the domain shape occurs, as a result of the competition between the wave radiation pressure and the capillary response of the lens border. Two archetypes of behaviour are observed. In the first, stable shapes are obtained experimentally and predicted theoretically as the exact solutions of a Riccati equation, and they result from the equilibrium between wave radiation pressure and capillarity. In the second, the radiation pressure exceeds the capillary response of the lens border and leads to non-equilibrium behaviours, with breaking into smaller domains that have a complex dynamics including spontaneous propagation. The authors are grateful to Université Franco-Italienne (UFI) for financial support.

  13. Interfacial Instability during Granular Erosion.

    PubMed

    Lefebvre, Gautier; Merceron, Aymeric; Jop, Pierre

    2016-02-12

    The complex interplay between the topography and the erosion and deposition phenomena is a key feature to model granular flows such as landslides. Here, we investigated the instability that develops during the erosion of a wet granular pile by a dry dense granular flow. The morphology and the propagation of the generated steps are analyzed in relation to the specific erosion mechanism. The selected flowing angle of the confined flow on a dry heap appears to play an important role both in the final state of the experiment, and for the shape of the structures. We show that the development of the instability is governed by the inertia of the flow through the Froude number. We model this instability and predict growth rates that are in agreement with the experiment results.

  14. Stellar explosions, instabilities, and turbulence

    SciTech Connect

    Drake, R. P.; Kuranz, C. C.; Miles, A. R.; Muthsam, H. J.; Plewa, T.

    2009-04-15

    It has become very clear that the evolution of structure during supernovae is centrally dependent on the pre-existing structure in the star. Modeling of the pre-existing structure has advanced significantly, leading to improved understanding and to a physically based assessment of the structure that will be present when a star explodes. It remains an open question whether low-mode asymmetries in the explosion process can produce the observed effects or whether the explosion mechanism somehow produces jets of material. In any event, the workhorse processes that produce structure in an exploding star are blast-wave driven instabilities. Laboratory experiments have explored these blast-wave-driven instabilities and specifically their dependence on initial conditions. Theoretical work has shown that the relative importance of Richtmyer-Meshkov and Rayleigh-Taylor instabilities varies with the initial conditions and does so in ways that can make sense of a range of astrophysical observations.

  15. Endoscopic endonasal odontoidectomy with anterior C1 arch preservation in reumathoid arthritis: long term follow-up and further technical improvement by anterior endoscopic C1-C2 screw fixation and fusion.

    PubMed

    Iacoangeli, Maurizio; Nasi, Davide; Colasanti, Roberto; Pan, Baogen; Re, Massimo; Di Rienzo, Alessandro; di Somma, Lucia; Dobran, Mauro; Specchia, Nicola; Scerrati, Massimo

    2017-08-22

    To examine the long-term outcomes (minimum of 4,5 years) of endoscopic endonasal odontoidectomy (EEO) with preservation of anterior C1 ring to treat irreducible ventral bulbo-medullary compressions in rheumatoid arthritis (RA) and to illustrate a novel technique of anterior pure endoscopic craniovertebral junction (CVJ) reconstruction and fusion. In fact, long-term clinical studies are still lacking to elucidate the effective role of EEO and whether it can obviate the need for posterior fixation. From November 2008 to January 2012, clinical and radiological data of 7 patients presenting with RA and associated irreducible bulbo-medullary compression treated with EEO were retrospectively analyzed. In all patients decompression was achieved by EEO with anterior C1 arch preservation. In the last two patients, after EEO, we used the spared anterior C1 arch for reconstruction of anterior column of CVJ by positioning, under pure endoscopic guidance, autologous bone and two tricortical screws between the anterior arch of C1 and the residual odontoid. All patients were examined clinically with Ranawat classification and radiographically with CT scan, MRI and dynamic x-ray immediately after surgery and during follow-up. Adequate bulbo-medullary decompression with anterior C1 arch preservation was obtained in all cases. At follow up (average 66,2 months; range 91-54 months) all patients experienced an improvement at least of one Ranawat classification level and presented no clinical and/or radiological signs of instability. EEO with anterior C1 arch sparing provides satisfying long term results for irreducible ventral CVJ lesions in RA. The preservation of anterior C1 arch and, when possible, the reconstruction of anterior CVJ can prevent the need for posterior fusion. Copyright © 2017 Elsevier Inc. All rights reserved.

  16. Distal anterior cerebral artery aneurysms.

    PubMed

    Lehecka, Martin; Dashti, Reza; Lehto, Hanna; Kivisaari, Riku; Niemelä, Mika; Hernesniemi, Juha

    2010-01-01

    Distal anterior cerebral artery (DACA) aneurysms, also known as pericallosal artery aneurysms, represent about 6% of all intracranial aneurysms. They are located on the A2-A5 segments of the anterior cerebral artery and on its distal branches. This paper summarizes present knowledge on radiological features, treatment options, treatment results, and long-term follow-up of DACA aneurysms. Typical features of DACA aneurysms are small size, broad base, and branches originating from the base. When ruptured, they cause intracerebral hematoma in nearly half of the cases. DACA aneurysms are nowadays more often treated with microsurgical clipping than endovascular coiling due to their distal location and morphologic features. With clipping the results are same or slightly better than for aneurysms at other locations, coiling is often associated with more complications than in other aneurysms. Clipping is a long-lasting treatment with very small recurrence rate, there is no long-term data available on efficacy of coiling yet. For ruptured DACA aneurysms the most important factors affecting outcome is the severity of initial bleeding and patient's age.

  17. [Anterior skull-base schwannoma].

    PubMed

    Esquivel-Miranda, Miguel; De la O Ríos, Elier; Vargas-Valenciano, Emmanuelle; Moreno-Medina, Eva

    2017-06-24

    Schwannomas are nerve sheath tumours that originate in Schwann cells. They are usually solitary and sporadic and manifest on peripheral, spinal or cranial nerves. Intracranial schwannomas tend to manifest on the eighth cranial nerve, particularly in patients with neurofibromatosis type2. Anterior skull-base schwannomas represent less than 1% of all intracranial schwannomas. They are more frequent in young people and are typically benign. These tumours represent a diagnostic challenge due to their rarity and difficult differential diagnosis, and numerous theories have been postulated concerning their origin and development. In this article, we present the case of a 13-year-old male with a single anterior cranial-base tumour not associated with neurofibromatosis who presented with headache, papilloedema, eye pain and loss of visual acuity. Complete resection of the tumour was performed, which was histopathologically diagnosed as a schwannoma. The patient made a complete clinical recovery with abatement of all symptoms. We conducted a review of the literature and found 66 cases worldwide with this diagnosis. We describe the most relevant epidemiological and clinical characteristics of this kind of tumour and its relation with the recently discovered and similar olfactory schwannoma. Copyright © 2017 Sociedad Española de Neurocirugía. Publicado por Elsevier España, S.L.U. All rights reserved.

  18. Mechanical Instabilities of Biological Tubes

    NASA Astrophysics Data System (ADS)

    Hannezo, Edouard; Prost, Jacques; Joanny, Jean-François

    2012-07-01

    We study theoretically the morphologies of biological tubes affected by various pathologies. When epithelial cells grow, the negative tension produced by their division provokes a buckling instability. Several shapes are investigated: varicose, dilated, sinuous, or sausagelike. They are all found in pathologies of tracheal, renal tubes, or arteries. The final shape depends crucially on the mechanical parameters of the tissues: Young’s modulus, wall-to-lumen ratio, homeostatic pressure. We argue that since tissues must be in quasistatic mechanical equilibrium, abnormal shapes convey information as to what causes the pathology. We calculate a phase diagram of tubular instabilities which could be a helpful guide for investigating the underlying genetic regulation.

  19. Beam instabilities in hadron synchrotrons

    DOE PAGES

    Metral, E.; T. Argyropoulos; Bartosik, H.; ...

    2016-04-01

    Beam instabilities cover a wide range of effects in particle accelerators and they have been the subjects of intense research for several decades. As the machines performance was pushed new mechanisms were revealed and nowadays the challenge consists in studying the interplays between all these intricate phenomena, as it is very often not possible to treat the different effects separately. Furthermore, the aim of this paper is to review the main mechanisms, discussing in particular the recent developments of beam instability theories and simulations.

  20. Beam instabilities in hadron synchrotrons

    SciTech Connect

    Metral, E.; T. Argyropoulos; Bartosik, H.; Biancacci, N.; Buffat, X.; Esteban Muller, J. F.; Herr, W.; Iadarola, G.; Lasheen, A.; Li, K.; Pieloni, T.; Quartullo, D.; Rumolo, G.; Salvant, B.; Shaposhnikova, E.; Tambasco, C.; Timko, H.; Zannini, C.; Burov, A.; Banfi, D.; Barranco, J.; Mounet, N.; Boine-Frankenheim, O.; Niedermayer, U.; Kornilov, V.; White, S.

    2016-04-01

    Beam instabilities cover a wide range of effects in particle accelerators and they have been the subjects of intense research for several decades. As the machines performance was pushed new mechanisms were revealed and nowadays the challenge consists in studying the interplays between all these intricate phenomena, as it is very often not possible to treat the different effects separately. Furthermore, the aim of this paper is to review the main mechanisms, discussing in particular the recent developments of beam instability theories and simulations.

  1. Political instability and illegal immigration.

    PubMed

    Campos, J E; Lien, D

    1995-01-01

    "Economic theory suggests that transnational migration results from the push-pull effect of wage differentials between host and source countries. In this paper, we argue that political instability exacerbates the migration flow, with greater instability leading to relatively larger flows. We conclude then that an optimal solution to the illegal immigration problem requires proper coordination of immigration and foreign policies by the host country. A narrow preoccupation with tougher immigration laws is wasteful and may be marginally effective." Emphasis is on the United States as a host country.

  2. Undulation Instability of Epithelial Tissues

    NASA Astrophysics Data System (ADS)

    Basan, Markus; Joanny, Jean-François; Prost, Jacques; Risler, Thomas

    2011-04-01

    Treating the epithelium as an incompressible fluid adjacent to a viscoelastic stroma, we find a novel hydrodynamic instability that leads to the formation of protrusions of the epithelium into the stroma. This instability is a candidate for epithelial fingering observed in vivo. It occurs for sufficiently large viscosity, cell-division rate and thickness of the dividing region in the epithelium. Our work provides physical insight into a potential mechanism by which interfaces between epithelia and stromas undulate and potentially by which tissue dysplasia leads to cancerous invasion.

  3. Research on aviation fuel instability

    NASA Technical Reports Server (NTRS)

    Baker, C. E.; Bittker, D. A.; Cohen, S. M.; Seng, G. T.

    1984-01-01

    The problems associated with aircraft fuel instability are discussed. What is currently known about the problem is reviewed and a research program to identify those areas where more research is needed is discussed. The term fuel instability generally refers to the gums, sediments, or deposits which can form as a result of a set of complex chemical reactions when a fuel is stored for a long period at ambient conditions or when the fuel is thermally stressed inside the fuel system of an aircraft.

  4. Stringy bounces and gradient instabilities

    NASA Astrophysics Data System (ADS)

    Giovannini, Massimo

    2017-04-01

    Bouncing solutions are obtained from a generally covariant action characterized by a potential which is a nonlocal functional of the dilaton field at two separated space-time points. Gradient instabilities are shown to arise in this context but they are argued to be nongeneric. After performing a gauge-invariant and a frame-invariant derivation of the evolution equations of the fluctuations, a heuristic criterion for the avoidance of pathological instabilities is proposed and corroborated by a number of explicit examples that turn out to be compatible with a quasiflat spectrum of curvature inhomogeneities for large wavelengths.

  5. Can arthroscopic revision surgery for shoulder instability be a fair option?

    PubMed

    De Giorgi, Silvana; Garofalo, Raffaele; Tafuri, Silvio; Cesari, Eugenio; Rose, Giacomo Delle; Castagna, Alessandro

    2014-04-01

    the aim of this study was to evaluate the role of arthroscopic capsuloplasty in the treatment of failed primary arthroscopic treatment of glenohumeral instability. we retrospectively examined at a minimum of 3-years follow-up 22 patients who underwent arthroscopic treatment between 1999 and 2007 who had recurrent anterior shoulder instability with a post-surgical failure. A statistical analysis was performed to evaluate which variable could influence the definitive result and clinical outcomes at final follow-up. A p value of less than 0.05 was considered significant. we observed after revision surgery an overall failure rate of 8/22 (36.4%) including frank dislocations, subluxations and also apprehension that seriously inhibit the patient's quality of life. No significant differences were observed in the examined parameters. according to our outcomes we generally do not recommend an arthroscopic revision procedure for failed instability surgery.

  6. Surgical Indications and Technique for Anterior Cruciate Ligament Reconstruction Combined with Lateral Extra-articular Tenodesis or Anterolateral Ligament Reconstruction.

    PubMed

    Vundelinckx, Bart; Herman, Benjamin; Getgood, Alan; Litchfield, Robert

    2017-01-01

    After anterior cruciate ligament (ACL) rupture, anteroposterior and rotational laxity in the knee causes instability, functional symptoms, and damage to other intra-articular structures. Surgical reconstruction aims to restore the stability in the knee, and to improve function and ability to participate in sports. It also protects cartilage and menisci from secondary injuries. Because of persistent rotational instability after ACL reconstruction, combined intra-articular and extra-articular procedures are more commonly performed. In this article, an overview of anatomy, biomechanical studies, current gold standard procedures, techniques, and research topics are summarized. Copyright © 2016 Elsevier Inc. All rights reserved.

  7. Anterior Cruciate: Methods of Physical Examination

    PubMed Central

    Grant, John; Kirby, R. Lee

    1982-01-01

    Tear of the anterior cruciate ligament is a common, serious injury. Since the long-range consequences of uncorrected anterior cruciate incompetence are better understood, and surgical and rehabilitative measures improved, early accurate diagnosis is increasingly important. Besides a careful history, diagnosis requires the use of specific physical examination methods to reproduce the symptomatic subluxation (anterior shift or internal rotation) and to assess functional performance of the knee. ImagesFig. 1Fig. 2Fig. 3 PMID:21286055

  8. Thrombosis of the Azygos Anterior Cerebral Artery

    PubMed Central

    Avelino, Marcelo Coelho; Bastos, Breno Braga; Moreira de Sousa, Rafael Soares

    2017-01-01

    The azygos anterior cerebral artery is a rare variant, characterized by the absence of the anterior communicating artery and the union of two proximal segments of the anterior cerebral artery, forming a single trunk and ascending through the interhemispheric fissure. The incidence in the population varies from 0.3 to 2%. The presence of occlusion for this vessel causes bifrontal infarcts, with potentially devastating functional consequences, hence the importance of recognizing this anatomical variation in imaging exams. PMID:28299225

  9. Incidental Anterior Cruciate Ligament Calcification: Case Report.

    PubMed

    Hayashi, Hisami; Fischer, Hans

    2016-03-01

    The calcification of knee ligaments is a finding noted only in a handful of case reports. The finding of an anterior cruciate ligament calcification has been reported once in the literature. Comparable studies involving the posterior cruciate ligament, medial collateral ligament and an ossicle within the anterior cruciate ligament are likewise discussed in reports of symptomatic patients. We report a case of incidentally discovered anterior cruciate ligament calcification. We discuss the likely etiology and clinical implications of this finding.

  10. Incidental Anterior Cruciate Ligament Calcification: Case Report

    PubMed Central

    Hayashi, Hisami; Fischer, Hans

    2016-01-01

    The calcification of knee ligaments is a finding noted only in a handful of case reports. The finding of an anterior cruciate ligament calcification has been reported once in the literature. Comparable studies involving the posterior cruciate ligament, medial collateral ligament and an ossicle within the anterior cruciate ligament are likewise discussed in reports of symptomatic patients. We report a case of incidentally discovered anterior cruciate ligament calcification. We discuss the likely etiology and clinical implications of this finding. PMID:27200163

  11. Anterior Cruciate Ligament Injuries in Baseball Players.

    PubMed

    Dugas, Jeffrey R; Bedford, Benjamin B; Andrachuk, John S; Scillia, Anthony J; Aune, Kyle T; Cain, E Lyle; Andrews, James R; Fleisig, Glenn S

    2016-11-01

    To determine common mechanisms of anterior cruciate ligament (ACL) injury in baseball players and to quantify the rate of return to play after primary surgical reconstruction and review intermediate clinical outcomes. Surgical injuries involving the ACL in youth, high school, collegiate, and professional baseball players were queried for an 11-year period (2001 to 2011). Over the study period, 42 baseball players were identified who had undergone arthroscopically assisted primary ACL reconstruction by 1 of 3 attending surgeons. Retrospective chart review was performed for all 42 patients to evaluate variables of age, level of competition, position, mechanism of injury, graft choice, and associated meniscal injuries. Twenty-six patients were reached for telephone survey and International Knee Documentation Committee questionnaire and they answered questions about their original injury and playing history. The most common mechanism of injury was fielding, followed by base running. Infielders and outfielders (32% each) were the most commonly injured position, followed by pitchers (29%). Among the 32 players for whom it could be determined, 30 (94%) were able to return to playing baseball at a mean follow-up of 4.2 years (range 1.0 to 9.9 years). The mean International Knee Documentation Committee score was 84.0 (range 63 to 91). Among the 26 patients contacted for telephone interview, no one required revision ACL surgery, but 3 required a subsequent procedure for meniscal tear. Twenty-five patients (96%) denied any episodes of instability in the knee after reconstruction. The overwhelming majority of baseball players that sustain ACL injuries do so while fielding or base running. Outfielders are significantly more likely than infielders to suffer ACL injuries while fielding versus base running. The results with respect to return to play are promising, as nearly all patients were able to return to baseball and none required a revision ACL surgery at a mean follow

  12. Acromioclavicular joint instability: anatomy, biomechanics and evaluation.

    PubMed

    Saccomanno, Maristella F; DE Ieso, Carmine; Milano, Giuseppe

    2014-01-01

    Acromioclavicular (AC) joint instability is a common source of pain and disability. The injury is most commonly a result of a direct impact to the AC joint. The AC joint is surrounded by a capsule and has an intra-articular synovium and an articular cartilage interface. An articular disc is usually present in the joint, but this varies in size and shape. The AC joint capsule is quite thin, but has considerable ligamentous support; there are four AC ligaments: superior, inferior, anterior and posterior. The coracoclavicular (CC) ligament complex consists of the conoid and trapezoid ligaments. They insert on the posteromedial and anterolateral region of the undersurface of the distal clavicle, respectively. The coracoid origin of the trapezoid covers the posterior half of the coracoid dorsum; the conoid origin is more posterior on the base of the coracoid. Several biomechanical studies showed that horizontal stability of the AC joint is mediated by the AC ligaments while vertical stability is mediated by the CC ligaments. The radiographic classification of AC joint injuries described by Rockwood includes six types: in type I injuries the AC ligaments are sprained, but the joint is intact; in type II injuries, the AC ligaments are torn, but the CC ligaments are intact; in type III injuries both the AC and the CC ligaments are torn; type IV injuries are characterized by complete dislocation with posterior displacement of the distal clavicle into or through the fascia of the trapezius; type V injuries are characterized by a greater degree of soft tissue damage; type VI injuries are inferior AC joint dislocations into a subacromial or subcoracoid position. The diagnosis of AC joint instability can be based on historical data, physical examination and imaging studies. The cross body adduction stress test has the greatest sensitivity, followed by the AC resisted extension test and the O'Brien test. Proper radiographic evaluation of the AC joint is necessary. The Zanca view

  13. Relationship between viscosity of the ankle joint complex and functional ankle instability for inversion ankle sprain patients.

    PubMed

    Lin, Che-Yu; Kang, Jiunn-Horng; Wang, Chung-Li; Shau, Yio-Wha

    2015-03-01

    Measurement of viscosity of the ankle joint complex is a novel method to assess mechanical ankle instability. In order to further investigate the clinical significance of the method, this study intended to investigate the relationship between ankle viscosity and severity of functional ankle instability. Cross-sectional study. 15 participants with unilateral inversion ankle sprain and 15 controls were recruited. Their ankles were further classified into stable and unstable ankles. Ankle viscosity was measured by an instrumental anterior drawer test. Severity of functional ankle instability was measured by the Cumberland Ankle Instability Tool. Unstable ankles were compared with stable ankles. Injured ankles were compared with uninjured ankles of both groups. The spearman's rank correlation coefficient was applied to determine the relationship between ankle viscosity and severity of functional ankle instability in unstable ankles. There was a moderate relationship between ankle viscosity and severity of functional ankle instability (r=-0.64, p<0.0001). Unstable ankles exhibited significantly lower viscosity (p<0.005) and more severe functional ankle instability (p<0.0001) than stable ankles. Injured ankles exhibited significantly lower viscosity and more severe functional ankle instability than uninjured ankles (p<0.0001). There was a moderate relationship between ankle viscosity and severity of functional ankle instability. This finding suggested that, severity of functional ankle instability may be partially attributed to mechanical insufficiencies such as the degenerative changes in ankle viscosity following the inversion ankle sprain. In clinical application, measurement of ankle viscosity could be a useful tool to evaluate severity of chronic ankle instability. Copyright © 2014 Sports Medicine Australia. Published by Elsevier Ltd. All rights reserved.

  14. From the unstable painful shoulder to multidirectional instability in the young athlete.

    PubMed

    Ren, Haifeng; Bicknell, Ryan T

    2013-10-01

    In conclusion, instability as a cause of shoulder pain in the young athlete is a difficult and often missed diagnosis. These young patients often seek treatment of shoulder pain but do not recall any episodes of shoulder instability. As a result, these uncommon, poorly described forms of instability are often misdiagnosed. A heightened clinical suspicion and an accurate, prompt diagnosis of instability is of paramount importance in this athletic group. It dictates appropriate treatment of the condition, avoids treatment delays and failure, provides better outcomes, and ensures timely return to play. UPS and MDI are two forms of this diagnosis. In UPS, patients at risk are young hyperlax athletes with a history of direct trauma or forceful overextension of the shoulder. They have shoulder pain that is described as deep anterior, reproduced with an anterior apprehension test and relieved with a relocation test. Soft tissue and/or bony lesions consistent with instability (observed on imaging or at arthroscopy) are necessary to confirm the diagnosis of UPS. Once the diagnosis is made, standard arthroscopic techniques with labrum reinsertion and/or anteroinferior capsule plication can lead to predictable good results and return to sport. In MDI, patients at risk are also young hyperlax athletes. However, these patients often do not have a history of trauma. They have shoulder pain that is often somewhat vague in location and is reproduced with a sulcus and/or hyper abduction test. Soft tissue and/or bony lesions consistent with instability are uncommon, with the exception of capsular laxity. The mainstay of treatment is physiotherapy rehabilitation. When surgery is necessary, open capsular shift and arthroscopic capsular plication are effective.

  15. Lending sociodynamics and economic instability

    NASA Astrophysics Data System (ADS)

    Hawkins, Raymond J.

    2011-11-01

    We show how the dynamics of economic instability and financial crises articulated by Keynes in the General Theory and developed by Minsky as the Financial Instability Hypothesis can be formalized using Weidlich’s sociodynamics of opinion formation. The model addresses both the lending sentiment of a lender in isolation as well as the impact on that lending sentiment of the behavior of other lenders. The risk associated with lending is incorporated through a stochastic treatment of loan dynamics that treats prepayment and default as competing risks. With this model we are able to generate endogenously the rapid changes in lending opinion that attend slow changes in lending profitability and find these dynamics to be consistent with the rise and collapse of the non-Agency mortgage-backed securities market in 2007/2008. As the parameters of this model correspond to well-known phenomena in cognitive and social psychology, we can both explain why economic instability has proved robust to advances in risk measurement and suggest how policy for reducing economic instability might be formulated in an experimentally sound manner.

  16. Biomechanics of complex shoulder instability.

    PubMed

    Degen, Ryan M; Giles, Joshua W; Thompson, Stephen R; Litchfield, Robert B; Athwal, George S

    2013-10-01

    Identification and treatment of the osseous lesions associated with complex shoulder instability remains challenging. Further biomechanical testing is required to delineate critical defect values and determine which treatments provide improved glenohumeral joint stability for the various defect sizes, while minimizing the associated complications.

  17. The Chemistry of Beer Instability

    ERIC Educational Resources Information Center

    Stewart, Graham G.

    2004-01-01

    Brewing of beer, one of the oldest biotechnology industries was one of the earliest processes to be undertaken on commercial basis. Biological instability involves contamination of bacteria, yeast, or mycelia fungi and there is always a risk in brewing that beer can become contaminated by micro-organisms.

  18. Confinement effects on electroconvective instability.

    PubMed

    Andersen, Mathias B; Wang, Karen M; Schiffbauer, Jarrod; Mani, Ali

    2017-03-01

    We present an analysis of hydrodynamic effects in systems involving ion transport from an aqueous electrolyte to an ion-selective surface. These systems are described by the Poisson-Nernst-Planck and Navier-Stokes equations. Historically, such systems were modeled by one-dimensional geometries with spatial coordinate in the direction of transport and normal to the ion-selective surface. Rubinstein and Zaltzman [JFM 579, 173-226 (2007)] showed that when such systems are unbounded in the transverse directions, a hydrodynamic instability can occur. This instability, referred to as electroconvective instability, leads to advective mixing, which results in overlimiting transport rates significantly beyond what is predicted from one-dimensional models. In this study, we present an analysis of electroconvection in confined systems, considering a broad range of applications including microfluidic systems and porous media. Our analysis reveals that full confinement in the transverse directions significantly suppresses electroconvection and overlimiting current. However, when at least one transverse direction allows for flow escape, such as in thin but wide channels or in porous media, the onset of instability is only weakly affected by confinement. We will also present a review of relevant literature and discuss how the present study resolves the contradictory contrasts between the results of recent work on this topic. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  19. Finite element shell instability analysis

    NASA Technical Reports Server (NTRS)

    1975-01-01

    Formulation procedures and the associated computer program for finite element thin shell instability analysis are discussed. Data cover: (1) formulation of basic element relationships, (2) construction of solution algorithms on both the conceptual and algorithmic levels, and (3) conduction of numerical analyses to verify the accuracy and efficiency of the theory and related programs therein are described.

  20. Edge instabilities of topological superconductors

    NASA Astrophysics Data System (ADS)

    Hofmann, Johannes S.; Assaad, Fakher F.; Schnyder, Andreas P.

    2016-05-01

    Nodal topological superconductors display zero-energy Majorana flat bands at generic edges. The flatness of these edge bands, which is protected by time-reversal and translation symmetry, gives rise to an extensive ground-state degeneracy. Therefore, even arbitrarily weak interactions lead to an instability of the flat-band edge states towards time-reversal and translation-symmetry-broken phases, which lift the ground-state degeneracy. We examine the instabilities of the flat-band edge states of dx y-wave superconductors by performing a mean-field analysis in the Majorana basis of the edge states. The leading instabilities are Majorana mass terms, which correspond to coherent superpositions of particle-particle and particle-hole channels in the fermionic language. We find that attractive interactions induce three different mass terms. One is a coherent superposition of imaginary s -wave pairing and current order, and another combines a charge-density-wave and finite-momentum singlet pairing. Repulsive interactions, on the other hand, lead to ferromagnetism together with spin-triplet pairing at the edge. Our quantum Monte Carlo simulations confirm these findings and demonstrate that these instabilities occur even in the presence of strong quantum fluctuations. We discuss the implications of our results for experiments on cuprate high-temperature superconductors.

  1. The Chemistry of Beer Instability

    ERIC Educational Resources Information Center

    Stewart, Graham G.

    2004-01-01

    Brewing of beer, one of the oldest biotechnology industries was one of the earliest processes to be undertaken on commercial basis. Biological instability involves contamination of bacteria, yeast, or mycelia fungi and there is always a risk in brewing that beer can become contaminated by micro-organisms.

  2. Weathering instability and landscape evolution

    NASA Astrophysics Data System (ADS)

    Phillips, Jonathan D.

    2005-04-01

    The argument in this paper is that the fundamental control on landscape evolution in erosional landscapes is weathering. The possibility of and evidence for instability in weathering at four scales is examined. The four scales are concerned with weathering processes, allocation of weathered products, the interrelations of weathering and denudation, and the topographic and isostatic responses to weathering-limited denudation (the regolith, hillslope, landscape unit, and landscape scales, respectively). The stability conditions for each model, and the circumstances under which the models themselves are relevant, are used to identify scale-related domains of stability and instability. At the regolith scale, the interactions among weathering rates, resistance, and moisture are unstable, but there are circumstances—over long timescales and where weathering is well advanced—under which the instability is irrelevant. At the hillslope scale, the system is stable when denudation is transport rather than weathering limited and where no renewal of exposure via regolith stripping occurs. At the level of landscape units, the stability model is based entirely on the mutual reinforcements of weathering and erosion. While this should generally lead to instability, the model would be stable where other, external controls of both weathering and erosion rates are stronger than the weathering-erosion feedbacks. At the broadest landscape scale, the inclusion of isostatic responses destabilizes erosion-topography-uplift relationships. Thus, if the spatial or temporal scale is such that isostatic responses are not relevant, the system may be stable. Essentially, instability is prevalent at local spatial scales at all but the longest timescales. Stability at intermediate spatial scales is contingent on whether weathering-erosion feedbacks are strong or weak, with stability being more likely at shorter and less likely at longer timescales. At the broadest spatial scales, instability is

  3. Singlet and triplet instability theorems

    SciTech Connect

    Yamada, Tomonori; Hirata, So

    2015-09-21

    A useful definition of orbital degeneracy—form-degeneracy—is introduced, which is distinct from the usual energy-degeneracy: Two canonical spatial orbitals are form-degenerate when the energy expectation value in the restricted Hartree–Fock (RHF) wave function is unaltered upon a two-electron excitation from one of these orbitals to the other. Form-degenerate orbitals tend to have isomorphic electron densities and occur in the highest-occupied and lowest-unoccupied molecular orbitals (HOMOs and LUMOs) of strongly correlated systems. Here, we present a mathematical proof of the existence of a triplet instability in a real or complex RHF wave function of a finite system in the space of real or complex unrestricted Hartree–Fock wave functions when HOMO and LUMO are energy- or form-degenerate. We also show that a singlet instability always exists in a real RHF wave function of a finite system in the space of complex RHF wave functions, when HOMO and LUMO are form-degenerate, but have nonidentical electron densities, or are energy-degenerate. These theorems provide Hartree–Fock-theory-based explanations of Hund’s rule, a singlet instability in Jahn–Teller systems, biradicaloid electronic structures, and a triplet instability during some covalent bond breaking. They also suggest (but not guarantee) the spontaneous formation of a spin density wave (SDW) in a metallic solid. The stability theory underlying these theorems extended to a continuous orbital-energy spectrum proves the existence of an oscillating (nonspiral) SDW instability in one- and three-dimensional homogeneous electron gases, but only at low densities or for strong interactions.

  4. Singlet and triplet instability theorems

    NASA Astrophysics Data System (ADS)

    Yamada, Tomonori; Hirata, So

    2015-09-01

    A useful definition of orbital degeneracy—form-degeneracy—is introduced, which is distinct from the usual energy-degeneracy: Two canonical spatial orbitals are form-degenerate when the energy expectation value in the restricted Hartree-Fock (RHF) wave function is unaltered upon a two-electron excitation from one of these orbitals to the other. Form-degenerate orbitals tend to have isomorphic electron densities and occur in the highest-occupied and lowest-unoccupied molecular orbitals (HOMOs and LUMOs) of strongly correlated systems. Here, we present a mathematical proof of the existence of a triplet instability in a real or complex RHF wave function of a finite system in the space of real or complex unrestricted Hartree-Fock wave functions when HOMO and LUMO are energy- or form-degenerate. We also show that a singlet instability always exists in a real RHF wave function of a finite system in the space of complex RHF wave functions, when HOMO and LUMO are form-degenerate, but have nonidentical electron densities, or are energy-degenerate. These theorems provide Hartree-Fock-theory-based explanations of Hund's rule, a singlet instability in Jahn-Teller systems, biradicaloid electronic structures, and a triplet instability during some covalent bond breaking. They also suggest (but not guarantee) the spontaneous formation of a spin density wave (SDW) in a metallic solid. The stability theory underlying these theorems extended to a continuous orbital-energy spectrum proves the existence of an oscillating (nonspiral) SDW instability in one- and three-dimensional homogeneous electron gases, but only at low densities or for strong interactions.

  5. Singlet and triplet instability theorems.

    PubMed

    Yamada, Tomonori; Hirata, So

    2015-09-21

    A useful definition of orbital degeneracy—form-degeneracy—is introduced, which is distinct from the usual energy-degeneracy: Two canonical spatial orbitals are form-degenerate when the energy expectation value in the restricted Hartree-Fock (RHF) wave function is unaltered upon a two-electron excitation from one of these orbitals to the other. Form-degenerate orbitals tend to have isomorphic electron densities and occur in the highest-occupied and lowest-unoccupied molecular orbitals (HOMOs and LUMOs) of strongly correlated systems. Here, we present a mathematical proof of the existence of a triplet instability in a real or complex RHF wave function of a finite system in the space of real or complex unrestricted Hartree-Fock wave functions when HOMO and LUMO are energy- or form-degenerate. We also show that a singlet instability always exists in a real RHF wave function of a finite system in the space of complex RHF wave functions, when HOMO and LUMO are form-degenerate, but have nonidentical electron densities, or are energy-degenerate. These theorems provide Hartree-Fock-theory-based explanations of Hund's rule, a singlet instability in Jahn-Teller systems, biradicaloid electronic structures, and a triplet instability during some covalent bond breaking. They also suggest (but not guarantee) the spontaneous formation of a spin density wave (SDW) in a metallic solid. The stability theory underlying these theorems extended to a continuous orbital-energy spectrum proves the existence of an oscillating (nonspiral) SDW instability in one- and three-dimensional homogeneous electron gases, but only at low densities or for strong interactions.

  6. A combination of Latarjet and Remplissage for treatment of severe glenohumeral instability and bone loss. A case report

    PubMed Central

    Ranne, Juha O.; Sarimo, Janne J.; Heinonen, Olli J.; Orava, Sakari Y.

    2013-01-01

    Recurrent glenohumeral instability is challenging to treat when large bony defects are present in the anterior glenoid and there is a large Hill–Sachs lesion. We present a case with extensive glenoid and humeral bone loss treated with open Latarjet procedure combined with posterior arthroscopic Remplissage. 3.5 years after surgery, there have been no dislocations or any subjective signs of instability. After half a year, the patient was able to return to work as an airline pilot. Constant score has improved from 33 to 74 and the Oxford instability score from 8 to 46. We find that in young patients with difficult instability combining the Latarjet and Remplissage is a good and replicable method. PMID:24403748

  7. Current-driven plasma instabilities in superconductors

    SciTech Connect

    Kempa, K.; Cen, J.; Bakshi, P.

    1989-02-01

    We examine here the possibility of current-driven plasma instabilities in superconductors in two temperature regimes. At low temperatures (Tapprox. =0) an instability can be generated in a layered system. Near the critical temperature (Tapprox. =T/sub c/) an instability can occur in a single superconductor for sufficiently large drifts which might be achievable in the new high-T/sub c/ materials. These instabilities offer possibilities for new radiation-source device applications.

  8. Observation of Parametric Instability in Advanced LIGO

    NASA Astrophysics Data System (ADS)

    Evans, Matthew; Gras, Slawek; Fritschel, Peter; Miller, John; Barsotti, Lisa; Martynov, Denis; Brooks, Aidan; Coyne, Dennis; Abbott, Rich; Adhikari, Rana X.; Arai, Koji; Bork, Rolf; Kells, Bill; Rollins, Jameson; Smith-Lefebvre, Nicolas; Vajente, Gabriele; Yamamoto, Hiroaki; Adams, Carl; Aston, Stuart; Betzweiser, Joseph; Frolov, Valera; Mullavey, Adam; Pele, Arnaud; Romie, Janeen; Thomas, Michael; Thorne, Keith; Dwyer, Sheila; Izumi, Kiwamu; Kawabe, Keita; Sigg, Daniel; Derosa, Ryan; Effler, Anamaria; Kokeyama, Keiko; Ballmer, Stefan; Massinger, Thomas J.; Staley, Alexa; Heinze, Matthew; Mueller, Chris; Grote, Hartmut; Ward, Robert; King, Eleanor; Blair, David; Ju, Li; Zhao, Chunnong

    2015-04-01

    Parametric instabilities have long been studied as a potentially limiting effect in high-power interferometric gravitational wave detectors. Until now, however, these instabilities have never been observed in a kilometer-scale interferometer. In this Letter, we describe the first observation of parametric instability in a gravitational wave detector, and the means by which it has been removed as a barrier to progress.

  9. Particular Threshold Behavior of Dusty Plasma Instabilities

    SciTech Connect

    Mikikian, M.; Cavarroc, M.; Coueedel, L.; Tessier, Y.; Boufendi, L.

    2008-09-07

    We show that some experimentally observed instabilities, concerning the void region of a dust cloud, are similar to oscillations obtained in chemical systems or neuronal dynamics. The time evolution of these instabilities follows a well-defined process particularly visible in the instability shape and frequency.

  10. Transverse instability of a rectangular bunch

    SciTech Connect

    Balbekov, V.; /Fermilab

    2005-12-01

    Transverse instability of a rectangular bunch is investigated. Known theory of bunched beam instability is modified to take into account 100% spread of synchrotron frequency. Series of equations adequately describing the instability is derived and solved analytically and numerically. The theory is applied to the Fermilab Recycler Ring.

  11. Transverse instability at the recycler ring

    SciTech Connect

    Ng, K.Y.; /Fermilab

    2004-10-01

    Sporadic transverse instabilities have been observed at the Fermilab Recycler Ring leading to increase in transverse emittances and beam loss. The driving source of these instabilities has been attributed to the resistive-wall impedance with space-charge playing an important role in suppressing Landau damping. Growth rates of the instabilities are computed. Remaining problems are discussed.

  12. Giant Cavernous Haemangioma of the Anterior Mediastinum

    PubMed Central

    Kaya, Seyda Ors; Samancılar, Ozgur; Usluer, Ozan; Acar, Tuba; Yener, Ali Galip

    2015-01-01

    Cavernous hemangiomas of the anterior mediastinum is rare. We present a case of a 56-year-old male patient with a giant cavernous hemangioma of the anterior mediastinum, 18 cm in diameters, approached by left posterolateral thoracotomy. To the best of our knowledge, such a unique case has not been previously presented in the literature. PMID:26644773

  13. Anterior cervical hypertrichosis: a sporadic case

    PubMed Central

    Bostan, Sezen; Yaşar, Şirin; Serdar, Zehra Aşiran; Gizlenti, Sevda

    2016-01-01

    Anterior cervical hypertrichosis is a very rare form of primary localized hypertrichosis. It consists of a tuft of terminal hair on the anterior neck just above the laryngeal prominence. The etiology is still unknown. In this article, we reported a 15-year-old female patient who presented to our clinic with a complaint of hypertrichosis on the anterior aspect of the neck for the last five years. Her past medical history revealed no pathology except for vesicoureteral reflux. On the basis of clinical presentation, our patient was diagnosed with anterior cervical hypertrichosis and she was considered to be a sporadic case due to lack of other similar cases in familial history. To date, 33 patients with anterior cervical hypertrichosis have been reported. Anterior cervical hypertrichosis can be associated with other abnormalities, but it frequently presents as an isolated defect (70%). The association of vesicoureteral reflux and anterior cervical hypertrichosis which was observed in our patient might be coincidental. So far, no case of anterior cervical hypertrichosis associated with vesicoureteral reflux has been reported in the literature. PMID:27103865

  14. Anterior cervical hypertrichosis: a sporadic case.

    PubMed

    Bostan, Sezen; Yaşar, Şirin; Serdar, Zehra Aşiran; Gizlenti, Sevda

    2016-03-01

    Anterior cervical hypertrichosis is a very rare form of primary localized hypertrichosis. It consists of a tuft of terminal hair on the anterior neck just above the laryngeal prominence. The etiology is still unknown. In this article, we reported a 15-year-old female patient who presented to our clinic with a complaint of hypertrichosis on the anterior aspect of the neck for the last five years. Her past medical history revealed no pathology except for vesicoureteral reflux. On the basis of clinical presentation, our patient was diagnosed with anterior cervical hypertrichosis and she was considered to be a sporadic case due to lack of other similar cases in familial history. To date, 33 patients with anterior cervical hypertrichosis have been reported. Anterior cervical hypertrichosis can be associated with other abnormalities, but it frequently presents as an isolated defect (70%). The association of vesicoureteral reflux and anterior cervical hypertrichosis which was observed in our patient might be coincidental. So far, no case of anterior cervical hypertrichosis associated with vesicoureteral reflux has been reported in the literature.

  15. Correlates of knee anterior laxity in sportswomen.

    PubMed

    Vauhnik, Renata; Morrissey, Matthew C; Rutherford, Olga M; Turk, Zmago; Pilih, Iztok A; Perme, Maja Pohar

    2009-12-01

    The purpose of this study was to evaluate whether any of the following factors are related to knee anterior laxity in healthy sportswomen: anthropometric characteristics, lower limb alignment characteristics, hormone-related factors and sport history. Six hundred and sixteen sportswomen were tested in the pre-season. The data have been analysed using linear regression for possible association of knee anterior laxity with other variables. Univariate linear regression indicated a positive association of knee anterior laxity with knee extension and navicular drop and a negative association with body height. Multivariate linear regression analysis showed statistically significant associations between knee anterior laxity and the combination of passive knee extension and the chosen sport (R(2)=0.089; p<0.05). The combination of passive knee extension and sport type was found to be related to the amount of knee anterior laxity, although the association was weak with this combination of factors able to explain only about 9% of the variability in laxity. Knowing which factors influence the amount of knee anterior laxity will help us to better interpret the results of knee anterior laxity testing and help us to understand the possible role of knee anterior laxity as a risk factor for knee injury.

  16. Recurrent anterior uveitis in Henoch Schonlein's vasculitis.

    PubMed

    Erer, Burak; Kamali, Sevil; Cingu, Kursat; Kilicaslan, Isin; Gul, Ahmet; Inanc, Murat; Aral, Orhan; Tugal-Tutkun, Ilknur

    2010-08-01

    Uveitis is an important component of many rheumatic diseases. The main causes of recurrent uveitis are seronegative spondylarthropathies and Behçet's disease. We describe a rare case of Henoch Schönlein vasculitis (HSV) along with multiple recurrences of acute anterior uveitis. In cases of skin rash and recurrent anterior uveitis, HSV should be considered in the differential diagnosis.

  17. Coracoid syndrome: a neglected cause of anterior shoulder pain

    PubMed Central

    GIGANTE, ANTONIO; BOTTEGONI, CARLO; BARBADORO, PAMELA

    2016-01-01

    Purpose the present prospective open-label study was designed to gain further insights into a condition thought to constitute a neglected but not uncommon syndrome characterized by anterior shoulder pain and tenderness to palpation over the apex of the coracoid process, not related to rotator cuff or pectoralis minor tendinopathy, long head of the biceps tendon disorders, or instability. The aim was to clarify its prevalence, clinical characteristics, differential diagnosis and response to corticosteroid injections. Methods patients with primary anterior shoulder pain precisely reproduced by deep pressure on the apex of the coracoid process were recruited. Patients with clinical or instrumental signs of other shoulder disorders were excluded. Patients were given an injection of triamcinolone acetonide 40 mg/ml 1 ml at the coracoid trigger point. They were evaluated after 15, 30 and 60 days and at 2 years using Equal Visual Analog Scale (EQ-VAS) and the Italian version of the Simple Shoulder Test (SST). Results between January 1 and December 31 2010, we treated 15 patients aged 26–66 years. The majority were women (86.67%). At 15 days, 6 (40%) patients reported complete resolution of their symptoms, while 9 (60%) complained of residual symptoms and received another injection. At 30 days, 14 (93.33%) patients were pain-free and very satisfied. At 2 years, the 14 patients who had been asymptomatic at 30 days reported that they had experienced no further pain or impaired shoulder function. The analysis of variance for repeated measures showed a significant effect of time on EQ-VAS and SST scores. Conclusions the present study documents the existence, and characteristics, of a “coracoid syndrome” characterized by anterior shoulder pain and tenderness to palpation over the apex of the coracoid process and showed that the pain is usually amenable to steroid treatment. This syndrome should be clearly distinguished from anterior shoulder pain due to other causes, in

  18. Interface instability modes in freezing colloidal suspensions: revealed from onset of planar instability

    PubMed Central

    Wang, Lilin; You, Jiaxue; Wang, Zhijun; Wang, Jincheng; Lin, Xin

    2016-01-01

    Freezing colloidal suspensions widely exists in nature and industry. Interface instability has attracted much attention for the understandings of the pattern formation in freezing colloidal suspensions. However, the interface instability modes, the origin of the ice banding or ice lamellae, are still unclear. In-situ experimental observation of the onset of interface instability remains absent up to now. Here, by directly imaging the initial transient stage of planar interface instability in directional freezing colloidal suspensions, we proposed three interface instability modes, Mullins-Sekerka instability, global split instability and local split instability. The intrinsic mechanism of the instability modes comes from the competition of the solute boundary layer and the particle boundary layer, which only can be revealed from the initial transient stage of planar instability in directional freezing. PMID:26996630

  19. Anterior capsulotomy using the CO2 laser

    NASA Astrophysics Data System (ADS)

    Barak, Adiel; Ma-Naim, Tova; Rosner, Mordechai; Eyal, Ophir; Belkin, Michael

    1998-06-01

    Continuous circular capsulorhexis (CCC) is the preferred technique for removal of the anterior capsule during cataract surgery due to this technique assuring accurate centration of the intraocular lens. During modern cataract surgery, especially with small or foldable intra ocular lenses, centration of the lens is obligatory. Radial tears at the margin of an anterior capsulotomy may be associated with the exit of at least one loop of an intraocular lens out of the capsular bag ('pea pod' effect) and its subsequent decentration. The anterior capsule is more likely to ream intact if the continuous circular capsulorhexis (CCC) technique is used. Although manual capsulorhexis is an ideal anterior capsulectomy technique for adults, many ophthalmologists are still uncomfortable with it and find it difficult to perform, especially in complicated cases such as these done behind small pupil, cataract extraction in children and pseudoexfoliation syndrome. We have developed a technique using a CO2 laser system for safe anterior capsulotomy and tested it in animal eyes.

  20. Repeat instability: mechanisms of dynamic mutations.

    PubMed

    Pearson, Christopher E; Nichol Edamura, Kerrie; Cleary, John D

    2005-10-01

    Disease-causing repeat instability is an important and unique form of mutation that is linked to more than 40 neurological, neurodegenerative and neuromuscular disorders. DNA repeat expansion mutations are dynamic and ongoing within tissues and across generations. The patterns of inherited and tissue-specific instability are determined by both gene-specific cis-elements and trans-acting DNA metabolic proteins. Repeat instability probably involves the formation of unusual DNA structures during DNA replication, repair and recombination. Experimental advances towards explaining the mechanisms of repeat instability have broadened our understanding of this mutational process. They have revealed surprising ways in which metabolic pathways can drive or protect from repeat instability.

  1. Developmental instability of gynodioecious Teucrium lusitanicum

    USGS Publications Warehouse

    Alados, C.L.; Navarro, T.; Cabezudo, B.; Emlen, J.M.; Freeman, C.

    1998-01-01

    Developmental instability was assessed in two geographical races of Teucrium lusitanicum using morphometric measures of vegetative and reproductive structures. T. lusitanicum is a gynodioecious species. Male sterile (female) individuals showed greater developmental instability at all sites. Plants located inland had higher developmental instability of vegetative characters and lower developmental instability of reproductive characters than coastal plants. These results support the contentions that (1) developmental instability is affected more by the disruption of co-adapted gene complexes than by lower heterozygosity, and (2) different habitat characteristics result in the differential response of vegetative and reproductive structures.

  2. A new classification system for shoulder instability.

    PubMed

    Kuhn, John E

    2010-04-01

    Glenohumeral joint instability is extremely common yet the definition and classification of instability remains unclear. In order to find the best ways to treat instability, the condition must be clearly defined and classified. This is particularly important so that treatment studies can be compared or combined, which can only be done if the patient population under study is the same. The purpose of this paper was to review the problems with historical methods of defining and classifying instability and to introduce the FEDS system of classifying instability, which was developed to have content validity and found to have high interobserver and intraobserver agreement.

  3. A Numerical Study of Feathering Instability

    NASA Astrophysics Data System (ADS)

    Lee, Wing-Kit; Wang, Hsiang-Hsu

    2016-06-01

    The stability of a spiral shock of self-gravitating, magnetized interstellar medium is studied by performing two-dimensional numerical simulations of a local patch of tight-winding spiral arm. As previously suggested by the linear studies, two types of instabilities are identified, namely, wiggle instability and feathering instability. The former instability occurs in the hydrodynamics limit and results in short wavelength perturbations. On the other hand, the feathering instability requires both self-gravitating and magnetic fields and results in wider structures.

  4. Modern management of patellar instability.

    PubMed

    Rhee, Shin-Jae; Pavlou, George; Oakley, Jeremy; Barlow, David; Haddad, Farres

    2012-12-01

    Recurrent patellofemoral instability is a disabling condition, attributed to a variety of anatomical aetiologies. Trochlear dysplasia, patella alta, an increased tibial tubercle trochlear groove distance of greater than 20 mm and soft tissue abnormalities such as a torn medial patellofemoral ligament and inadequate vastus medialis obliquus are all factors to be considered. Management of this condition remains difficult and controversial and knowledge of the functional anatomy and biomechanics of the patellofemoral joint, a detailed history and clinical examination, and an accurate patient assessment are all imperative to formulate an appropriate management plan. Surgical treatment is based on the underlying anatomical pathology with an aim to restore normal patellofemoral kinematics. We summarise aspects of assessment, treatment and outcome of patellofemoral instability and propose an algorithm of treatment.

  5. Granular Rayleigh-Taylor instability

    SciTech Connect

    Vinningland, Jan Ludvig; Johnsen, Oistein; Flekkoey, Eirik G.; Maaloey, Knut Joergen; Toussaint, Renaud

    2009-06-18

    A granular instability driven by gravity is studied experimentally and numerically. The instability arises as grains fall in a closed Hele-Shaw cell where a layer of dense granular material is positioned above a layer of air. The initially flat front defined by the grains subsequently develops into a pattern of falling granular fingers separated by rising bubbles of air. A transient coarsening of the front is observed right from the start by a finger merging process. The coarsening is later stabilized by new fingers growing from the center of the rising bubbles. The structures are quantified by means of Fourier analysis and quantitative agreement between experiment and computation is shown. This analysis also reveals scale invariance of the flow structures under overall change of spatial scale.

  6. Numerical analysis of engine instability

    NASA Astrophysics Data System (ADS)

    Habiballah, M.; Dubois, I.

    Following a literature review on numerical analyses of combustion instability, to give the state of the art in the area, the paper describes the ONERA methodology used to analyze the combustion instability in liquid propellant engines. Attention is also given to a model (named Phedre) which describes the unsteady turbulent two-phase reacting flow in a liquid rocket engine combustion chamber. The model formulation includes axial or radial propellant injection, baffles, and acoustic resonators modeling, and makes it possible to treat different engine types. A numerical analysis of a cryogenic engine stability is presented, and the results of the analysis are compared with results of tests of the Viking engine and the gas generator of the Vulcain engine, showing good qualitative agreement and some general trends between experiments and numerical analysis.

  7. Circulation in blast driven instabilities

    NASA Astrophysics Data System (ADS)

    Henry de Frahan, Marc; Johnsen, Eric

    2016-11-01

    Mixing in many natural phenomena (e.g. supernova collapse) and engineering applications (e.g. inertial confinement fusion) is often initiated through hydrodynamic instabilities. Explosions in these systems give rise to blast waves which can interact with perturbations at interfaces between different fluids. Blast waves are formed by a shock followed by a rarefaction. This wave profile leads to complex time histories of interface acceleration. In addition to the instabilities induced by the acceleration field, the rarefaction from the blast wave decompresses the material at the interface, further increasing the perturbation growth. After the passage of the wave, circulation circulation generated by the blast wave through baroclinic vorticity continues to act upon the interface. In this talk, we provide scaling laws for the circulation and amplitude growth induced by the blast wave. Numerical simulations of the multifluid Euler equations solved using a high-order accurate Discontinuous Galerkin method are used to validate the theoretical results.

  8. Instability of colliding metastable strings

    NASA Astrophysics Data System (ADS)

    Hiramatsu, Takashi; Eto, Minoru; Kamada, Kohei; Kobayashi, Tatsuo; Ookouchi, Yutaka

    2014-01-01

    The breaking of U(1) R symmetry plays a crucial role in modeling the breaking of supersymmetry (SUSY). In the models that possess both SUSY preserving and SUSY breaking vacua, tube-like cosmic strings called R-tubes, whose surfaces are constituted by domain walls interpolating a false and a true vacuum with some winding numbers, can exist. Their (in)stability can strongly constrain SUSY breaking models theirselves. In the present study, we investigate the dynamical (in)stability of two colliding metastable tube-like strings by field-theoretic simulations. From them, we find that the strings become unstable, depending on the relative collision angle and speed of two strings, and the false vacuum is eventually filled out by the true vacuum owing to rapid expansion of the strings or unstable bubbles created as remnants of the collision.

  9. Morphological instability of failure fronts

    SciTech Connect

    Grinfeld, M.A.; Schoenfeld, S.E.; Wright, T.W.

    2006-03-06

    There are various observations and experiments showing that, in addition to standard shock-wave fronts, which propagate with high trans-sonic velocities, some other much slower wave fronts can propagate within substance undergoing intensive damage. These moving fronts propagate within intact substance leaving behind them intensively damaged substance. These fronts were coined as failure waves. The failure waves can be modeled differently--in this letter they are modeled as sharp interfaces separating two states: the intact and comminuted states. Several penetration experiments with transparent glasses and ceramics have shown that failure fronts have an extremely rough morphology. We suggest a simple thermodynamic theory which allows interpreting appearance of the roughness as a manifestation of morphological instability of failure fronts. For the case of isotropic phases the instability criterion is presented in explicit form.

  10. Research on aviation fuel instability

    NASA Technical Reports Server (NTRS)

    Baker, C. E.; Bittker, D. A.; Cohen, S. M.; Seng, G. T.

    1984-01-01

    Current aircraft turbine fuels do not present a significant problem with fuel thermal stability. However, turbine fuels with broadened properties or nonpetroleum derived fuels may have reduced thermal stability because of their higher content of olefins, heteroatoms, and trace metals. Moreover, advanced turbine engines will increase the thermal stress on fuels because of their higher pressure ratios and combustion temperature. In recognition of the importance of this problem, NASA Lewis is currently engaged in a broadly based research effort to better understand the underlying causes of fuel thermal degradation. The progress and status of our various activities in this area are discussed. Topics covered include: nature of fuel instability and its temperature dependence, methods of measuring the instability, chemical mechanisms involved in deposit formation, and instrumental methods for characterizing fuel deposits. Finally, some preliminary thoughts on design approaches for minimizing the effects of lowered thermal stability are briefly discussed.

  11. Anterior translation and rotational stability of anterior cruciate ligament-deficient knees during walking: speed and turning direction.

    PubMed

    Yim, Ji Hyeon; Seon, Jong Keun; Kim, Young Kwan; Jung, Sung Taek; Shin, Choongsoo S; Yang, Dong Hyun; Rhym, Inn Su; Song, Eun Kyoo

    2015-01-01

    Anterior cruciate ligament (ACL) rupture is one of the most common injuries associated with the knee. After ACL injury, knee joint stability can be altered, resulting in abnormal loading during functional activities. Since ACL-deficient (ACLD) knees are also vulnerable to translational and rotational instability, patients need to be wary of certain motions encountered in daily life. The present study investigated the effect of walking speed and pivoting directional change during gait on knee joint kinematics of ACLD knees. We hypothesized that faster walking and crossover turning would induce severe kinematic changes. Thirty-five patients (22 males and 13 females) having a unilateral isolated subacute ACLD knee (from 1 to 3 months after injury) and contralateral intact (CLI) knee participated in this study. Spatiotemporal parameters, three-dimensional (3D) knee joint angles, and anterior-posterior (AP) translation were obtained by a 3D high-speed motion-capturing system. The CLI knee of each patient served as the control. The calculated AP stability and knee joint angles were used to test the research hypothesis. Mixed two-way repeated measures analysis of variance was performed to clarify the effects of walking speed and pivoting direction with a significance of 0.05. When a significance of mean comparison was detected, a post hoc test was performed. Significant and consistent increased AP translation of the tibia relative to the femur at the whole stance phase of the gait cycle was evident in ACLD knees compared to CLI knees for normal and faster (20 % greater than normal) walking speeds. Faster walking speed did not induce significantly more anterior location of the tibia. In addition, ACLD knees were significantly less extended than CLI knees during a large portion of midstance. Although there was a consistent varus offset between the curves of ACLD and CLI knees, the difference did not reach statistical significance during the stance phase. Also, ACLD knees

  12. Genomic Instability and Breast Cancer

    DTIC Science & Technology

    2009-10-01

    mentedwith 10% fetal bovine serum and 1% penicillin /streptomycin at 37 °C in a humidified incubatorwith 5% CO2 (v/v). Mouse embryonic fibroblast (MEF) cells...weremaintained in RPMI medium supplemented with 10% fetal bovine serum and 1% penicillin and streptomycin. Human mammary epithelial cells (HMEC...integrity. Accordingly, tumor cells derived from these patients exhibit hypersensitivity to DNA damaging agents and display genomic instability (2–4

  13. [Instrumental diagnosis in shoulder instability].

    PubMed

    Lalla, E; Rosa, D; Grillo, G; Belfiore, G

    1989-01-01

    The authors call attention to the pathology caused by glenohumeral instability and, in particular, to painful shoulders in athletes which so often cause problems in diagnosis. An instrumental protocol for diagnosis is suggested, based on several specific radiographic views, Ct scan and arthro-Ct scan, with double contrast medium, the latter having the task of determining lesion which would not otherwise be able to be studied.

  14. Morphological instabilities of lamellar eutectics

    SciTech Connect

    Karma, A.; Sarkissian, A.

    1996-03-01

    The authors present the results of a numerical study based on the boundary integral technique of interfacial pattern formation in directional solidification of thin-film lamellar eutectics at low velocity. Microstructure selection maps that identify the stability domains of various steady-state and nonsteady-state growth morphologies in the spacing-composition ({lambda} {minus} C{sub 0}) plane are constructed for the transparent organic alloy CBr{sub 4}-C{sub 2}Cl{sub 6} and for a model eutectic alloy with two solid phases of identical physical properties. In CBr{sub 4}-C{sub 2}Cl{sub 6}, the basic set of instabilities that limit steady-state growth is richer than expected. It consists of three primary instabilities, two of which are oscillatory, which bound the domain of the commonly observed axisymmetric lamellar morphology, and two secondary oscillatory instabilities, which bound the domain of the nonaxisymmetric (tilted) lamellar morphology. Four stable oscillatory microstructures, at least three of which have been seen experimentally, are predicted to occur in unstable regimes. In the model alloy, the structure is qualitatively similar, except that a stable domain of tilted steady-state growth is not found, in agreement with previous random-walk simulations. Furthermore, the composition range of stability of the axisymmetric morphology decreases sharply with increasing spacing away from minimum undercooling but extends further off-eutectic than predicted by the competitive growth criterion. In addition, oscillations with a wavelength equal to two {lambda} lead to lamella termination at a small distance above the onset of instability. The implications of these two features for the eutectic to dendrite transition are examined with the conclusion that in the absence of heterogeneous nucleation, this transition should be histeritic at small velocity and temperature gradient.

  15. Combustion instability modeling and analysis

    SciTech Connect

    Santoro, R.J.; Yang, V.; Santavicca, D.A.; Sheppard, E.J.

    1995-12-31

    It is well known that the two key elements for achieving low emissions and high performance in a gas turbine combustor are to simultaneously establish (1) a lean combustion zone for maintaining low NO{sub x} emissions and (2) rapid mixing for good ignition and flame stability. However, these requirements, when coupled with the short combustor lengths used to limit the residence time for NO formation typical of advanced gas turbine combustors, can lead to problems regarding unburned hydrocarbons (UHC) and carbon monoxide (CO) emissions, as well as the occurrence of combustion instabilities. The concurrent development of suitable analytical and numerical models that are validated with experimental studies is important for achieving this objective. A major benefit of the present research will be to provide for the first time an experimentally verified model of emissions and performance of gas turbine combustors. The present study represents a coordinated effort between industry, government and academia to investigate gas turbine combustion dynamics. Specific study areas include development of advanced diagnostics, definition of controlling phenomena, advancement of analytical and numerical modeling capabilities, and assessment of the current status of our ability to apply these tools to practical gas turbine combustors. The present work involves four tasks which address, respectively, (1) the development of a fiber-optic probe for fuel-air ratio measurements, (2) the study of combustion instability using laser-based diagnostics in a high pressure, high temperature flow reactor, (3) the development of analytical and numerical modeling capabilities for describing combustion instability which will be validated against experimental data, and (4) the preparation of a literature survey and establishment of a data base on practical experience with combustion instability.

  16. Finite temperature instability for compactification

    SciTech Connect

    Accetta, F.S.; Kolb, E.W.

    1986-03-01

    We consider finite temperature effects upon theories with extra dimensions compactified via vacuum stress energy (Casimir) effects. For sufficiently high temperature, a static configuration for the internal space is impossible. At somewhat lower temperatures, there is an instability due to thermal fluctuations of radius of the compact dimensions. For both cases, the Universe can evolve to a de Sitter-like expansion of all dimensions. Stability to late times constrains the initial entropy of the universe. 28 refs., 1 fig., 2 tabs.

  17. Migrational Instabilities in Particle Suspensions

    NASA Technical Reports Server (NTRS)

    Goddard, Joe D.

    1996-01-01

    This work deals with an instability arising from the shear-induced migration of particles in dense suspensions coupled with a dependence of viscosity on particle concentration. The analysis summarized here treats the inertialess (Re = O) linear stability of homogeneous simple shear flows for a Stokesian suspension model of the type proposed by Leighton and Acrivos (1987). Depending on the importance of shear-induced migration relative to concentration-driven diffusion, this model admits short-wave instability arising from wave-vector stretching by the base flow and evolving into particle-depleted shear bands. Moreover, this instability in the time-dependent problem corresponds to loss of ellipticity in the associated static problem (Re = O, Pe = O). While the isotropic version of the Leighton-Acrivos model is found to be stable with their experimentally determined parameters for simple shear, it is known that the stable model does not give a good quantitative description of particle clustering in the core of pipe flow (Nott and Brady 1994). This leads to the conjecture that an appropriate variant on the above model could explain such clustering as a two-phase bifurcation in the base flow.

  18. Gravitational instabilities in astrophysical fluids

    NASA Astrophysics Data System (ADS)

    Tohline, Joel E.

    1990-01-01

    Over the past decade, the significant advancements that have been made in the development of computational tools and numerical techniques have allowed astrophysicists to begin to model accurately the nonlinear growth of gravitational instabilities in a variety of physical systems. The fragmentation or rotationally driven fission of dynamically evolving, self-gravitating ``drops and bubbles'' is now routinely modeled in full three-dimensional generality as we attempt to understand the behavior of protostellar clouds, rotating stars, galaxies, and even the primordial soup that defined the birth of the universe. A brief review is presented here of the general insights that have been gained from studies of this type, followed by a somewhat more detailed description of work, currently underway, that is designed to explain the process of binary star formation. A short video animation sequence, developed in conjunction with some of the research being reviewed, illustrates the basic-nature of the fission instability in rotating stars and of an instability that can arise in a massive disk that forms in a protostellar cloud.

  19. Soft Dielectrics: Heterogeneity and Instabilities

    NASA Astrophysics Data System (ADS)

    Rudykh, Stephan; Debotton, Gal; Bhattacharya, Kaushik

    2012-02-01

    Dielectric Elastomers are capable of large deformations in response to electrical stimuli. Heterogeneous soft dielectrics with proper microstructures demonstrate much stronger electromechanical coupling than their homogeneous constituents. In turn, the heterogeneity is an origin for instability developments leading to drastic change in the composite microstructure. In this talk, the electromechanical instabilities are considered. Stability of anisotropic soft dielectrics is analyzed. Ways to achieve giant deformations and manipulating extreme material properties are discussed. 1. S. Rudykh and G. deBotton, ``Instabilities of Hyperelastic Fiber Composites: Micromechanical Versus Numerical Analyses.'' Journal of Elasticity, 2011. http://dx.doi.org/2010.1007/s10659-011-9313-x 2. S. Rudykh, K. Bhattacharya and G. deBotton, ``Snap-through actuation of thick-wall electroactive balloons.'' International Journal of Non-Linear Mechanics, 2011. http://dx.doi.org/10.1016/j.ijnonlinmec.2011.05.006 3. S. Rudykh and G. deBotton, ``Stability of Anisotropic Electroactive Polymers with Application to Layered Media.'' Zeitschrift f"ur angewandte Mathematik und Physik, 2011. http://dx.doi.org/10.1007/s00033-011-0136-1 4. S. Rudykh, A. Lewinstein, G. Uner and G. deBotton, ``Giant Enhancement of the Electromechanical Coupling in Soft Heterogeneous Dielectrics.'' 2011 http://arxiv.org/abs/1105.4217v1

  20. Pattern Generation by Dissipative Parametric Instability.

    PubMed

    Perego, A M; Tarasov, N; Churkin, D V; Turitsyn, S K; Staliunas, K

    2016-01-15

    Nonlinear instabilities are responsible for spontaneous pattern formation in a vast number of natural and engineered systems, ranging from biology to galaxy buildup. We propose a new instability mechanism leading to pattern formation in spatially extended nonlinear systems, which is based on a periodic antiphase modulation of spectrally dependent losses arranged in a zigzag way: an effective filtering is imposed at symmetrically located wave numbers k and -k in alternating order. The properties of the dissipative parametric instability differ from the features of both key classical concepts of modulation instabilities, i.e., the Benjamin-Feir instability and the Faraday instabiltyity. We demonstrate how the dissipative parametric instability can lead to the formation of stable patterns in one- and two-dimensional systems. The proposed instability mechanism is generic and can naturally occur or can be implemented in various physical systems.

  1. Microphysics of Cosmic Ray Driven Plasma Instabilities

    NASA Astrophysics Data System (ADS)

    Bykov, A. M.; Brandenburg, A.; Malkov, M. A.; Osipov, S. M.

    Energetic nonthermal particles (cosmic rays, CRs) are accelerated in supernova remnants, relativistic jets and other astrophysical objects. The CR energy density is typically comparable with that of the thermal components and magnetic fields. In this review we discuss mechanisms of magnetic field amplification due to instabilities induced by CRs. We derive CR kinetic and magnetohydrodynamic equations that govern cosmic plasma systems comprising the thermal background plasma, comic rays and fluctuating magnetic fields to study CR-driven instabilities. Both resonant and non-resonant instabilities are reviewed, including the Bell short-wavelength instability, and the firehose instability. Special attention is paid to the longwavelength instabilities driven by the CR current and pressure gradient. The helicity production by the CR current-driven instabilities is discussed in connection with the dynamo mechanisms of cosmic magnetic field amplification.

  2. Microphysics of Cosmic Ray Driven Plasma Instabilities

    NASA Astrophysics Data System (ADS)

    Bykov, A. M.; Brandenburg, A.; Malkov, M. A.; Osipov, S. M.

    2013-10-01

    Energetic nonthermal particles (cosmic rays, CRs) are accelerated in supernova remnants, relativistic jets and other astrophysical objects. The CR energy density is typically comparable with that of the thermal components and magnetic fields. In this review we discuss mechanisms of magnetic field amplification due to instabilities induced by CRs. We derive CR kinetic and magnetohydrodynamic equations that govern cosmic plasma systems comprising the thermal background plasma, comic rays and fluctuating magnetic fields to study CR-driven instabilities. Both resonant and non-resonant instabilities are reviewed, including the Bell short-wavelength instability, and the firehose instability. Special attention is paid to the longwavelength instabilities driven by the CR current and pressure gradient. The helicity production by the CR current-driven instabilities is discussed in connection with the dynamo mechanisms of cosmic magnetic field amplification.

  3. Pattern Generation by Dissipative Parametric Instability

    NASA Astrophysics Data System (ADS)

    Perego, A. M.; Tarasov, N.; Churkin, D. V.; Turitsyn, S. K.; Staliunas, K.

    2016-01-01

    Nonlinear instabilities are responsible for spontaneous pattern formation in a vast number of natural and engineered systems, ranging from biology to galaxy buildup. We propose a new instability mechanism leading to pattern formation in spatially extended nonlinear systems, which is based on a periodic antiphase modulation of spectrally dependent losses arranged in a zigzag way: an effective filtering is imposed at symmetrically located wave numbers k and -k in alternating order. The properties of the dissipative parametric instability differ from the features of both key classical concepts of modulation instabilities, i.e., the Benjamin-Feir instability and the Faraday instabiltyity. We demonstrate how the dissipative parametric instability can lead to the formation of stable patterns in one- and two-dimensional systems. The proposed instability mechanism is generic and can naturally occur or can be implemented in various physical systems.

  4. Anterior Cruciate Ligament Graft Choices

    PubMed Central

    Macaulay, Alec A.; Perfetti, Dean C.; Levine, William N.

    2012-01-01

    Context: Reconstruction of the anterior cruciate ligament (ACL) is a common surgical procedure; however, there is no consensus to what the best graft option is to replace the injured ACL. The main options available consist of allografts and autografts, which include patellar tendon, hamstring tendon, and quadriceps tendon autografts. Evidence Acquisition: The PubMed database was searched in August 2010 for English-language articles pertaining to ACL grafts. Results: Postoperative outcome variables were analyzed to determine similarities and differences among the different graft options. These variables include stability, strength, function, return to sports, patient satisfaction, complications, and cost. Conclusions: Both allografts and the 3 main options for autografts can provide excellent results in ACL reconstruction and lead to a high percentage of satisfied patients. However, differences exist among the graft choices. Both the similarities and the differences are important to discuss with a patient who will be undergoing ACL reconstruction so that he or she has the best information available when making a choice of graft. PMID:23016071

  5. Ameloblastoma of the anterior mandible

    PubMed Central

    Hariram; Mohammad, Shadab; Malkunje, Laxman R.; Singh, Nimisha; Das, Sugata; Mehta, Gagan

    2014-01-01

    Ameloblastoma or adamantinoma is the rarest of the three forms of tumor of the odontogenic type. They are benign, locally aggressive neoplasms arising from ameloblasts, which typically occur at the angle of the mandible, and are often associated with an un-erupted tooth and must, therefore, be differentiated from a dentigerous cyst which will be centered on the crown. When in the maxilla (less common), they are located in the premolar region, and can extend up in the maxillary sinus. Ameloblastoma is reported to constitute about 1-3% of tumors and cysts of the jaws. The tumor is by far more common in the mandible than in the maxilla and shows predilection for various parts of the mandible in different racial groups. The relative frequency of the mandible to maxilla is reported as varying from 80-20% to 99-1%. Here, we are representing a case of ameloblastoma of anterior mandible which was considered as a rare site of occurrence. PMID:25298718

  6. Anterior space management: interdisciplinary concepts.

    PubMed

    Ittipuriphat, Iyarint; Leevailoj, Chalermpol

    2013-02-01

    This case report describes the treatment of one patient with maxillary anterior spacing, caused by bilateral lateral peg-shaped incisors, using a planned sequence of multidisciplinary approaches for esthetic treatment. An asymmetrical gingival line was visible when the patient smiled. To evaluate the desired gingival level and the proportion of restoration to be made using the recurring esthetic dental (RED) proportion method, a diagnostic wax-up model was fabricated. Esthetic crown lengthening corrected the gingival line. RED proportion analysis suggested minor tooth movement prior to any restoration. Two weeks' use of an orthodontic removable appliance with finger springs achieved the proper dental proportion. Home whitening was prescribed for 2 weeks, with an additional 2-week waiting period to ensure tooth color stability. Resin composite treatment corrected the mesial contour of the maxillary canines and reduced the space between the canines and lateral incisors. Final restoration was obtained by placing ceramic veneers on the lateral peg-shaped incisors. The esthetic treatment achieved excellent results; after veneer cementation, the patient exhibited greater confidence with a new smile. Esthetic dental treatment requires various disciplines to achieve the treatment goal. This case report is an example of well-planned sequences of treatment from the beginning to complete treatment. By conservative and practical treatment approaches used in this case, the clinician will be able to manage to obtain the highest result of esthetic treatment. © 2012 Wiley Periodicals, Inc.

  7. Results of arthroscopic capsulolabral repair: Bankart lesion versus anterior labroligamentous periosteal sleeve avulsion lesion.

    PubMed

    Ozbaydar, Mehmet; Elhassan, Bassem; Diller, David; Massimini, Daniel; Higgins, Laurence D; Warner, Jon J P

    2008-11-01

    The purpose of this study was to evaluate the results of arthroscopic capsulolabral repair for traumatic anterior shoulder instability and to compare the outcome in patients who have Bankart lesions versus those with anterior labroligamentous periosteal sleeve avulsion (ALPSA) lesions. This study included 99 patients (93 shoulders), 72 male and 17 female, with a mean age of 32 years, who underwent arthroscopic Bankart repair for traumatic, recurrent anterior shoulder instability, by use of suture anchors. In 67 shoulders (72%) a discrete Bankart lesion was repaired, and in 26 shoulders (28%) an ALPSA lesion was repaired. The 2 groups were analyzed with regard to the number of preoperative dislocations and number of postoperative recurrences. At a mean follow-up of 47 months (range, 24 to 98 months), recurrence of instability was documented in 10 shoulders (10.7%). Of the shoulders, 5 had Bankart lesions (7.4%) and 5 had ALPSA lesions (19.2%) (P = .0501). The mean number of dislocations or subluxations before the index surgery was significantly higher in the ALPSA group (mean, 12.3 [range, 2 to 57]) than in the Bankart group (mean, 4.9 [range, 2 to 24]) (P < .05). However, there were no significant differences in the number of anchors used, incidence of minor glenoid erosion, or incidence of bony Bankart lesions between the groups (P > .05 for all). Patients with ALPSA lesions present with a higher number of recurrent dislocations than those with discrete Bankart lesions. In addition, the failure rate after arthroscopic capsulolabral repair is higher in the ALPSA group than in the Bankart group. Level IV, therapeutic case series.

  8. Anatomy of the capsulolabral complex and rotator interval related to glenohumeral instability.

    PubMed

    Itoigawa, Yoshiaki; Itoi, Eiji

    2016-02-01

    The glenohumeral joint with instability is a common diagnosis that often requires surgery. The aim of this review was to present an overview of the anatomy of the glenohumeral joint with emphasis on instability based on the current literature and to describe the detailed anatomy and anatomical variants of the glenohumeral joint associated with anterior and posterior shoulder instability. A review was performed using PubMed/MEDLINE using key words: Search terms were "glenohumeral", "shoulder instability", "cadaver", "rotator interval", "anatomy", and "anatomical study". During the last decade, the interest in both arthroscopic repair techniques and surgical anatomy of the glenohumeral ligament (superior, middle, and inferior), labrum, and rotator interval has increased. Understanding of the rotator interval and attachment of the inferior glenohumeral ligament on the glenoid or humeral head have evolved significantly. The knowledge of the detailed anatomy and anatomical variations is essential for the surgeon in order to understand the pathology, make a correct diagnosis of instability, and select proper treatment options. Proper understanding of anatomical variants can help us avoid misdiagnosis. Level of evidence V.

  9. Atypical Chronic Ankle Instability in a Pediatric Population Secondary to Distal Fibula Avulsion Fracture Nonunion.

    PubMed

    El Ashry, Saad R; El Gamal, Tarek A; Platt, Simon R

    Chronic ankle instability is a disabling condition, often occurring as a result of traumatic ankle injury. A paucity of published data is available documenting chronic ankle instability in the pediatric population. Much of the data has been confined to the adult population. We present 2 cases of chronic ankle instability, 1 in a 12-year-old and 1 in a 9-year-old patient. Unlike the typical adult etiology, the cause of instability was a dysfunctional lateral ligamentous complex as a consequence of bony avulsion of the tip of the fibula. Both patients had sustained a twisting injury to the ankle. The fractures failed to unite. The nonunion resulted in dysfunction of the anterior talofibular ligament with consequent chronic ankle instability. At the initial clinical assessment, magnetic resonance imaging was requested for both patients. In patient 1 (12 years old), the fracture was fixed with 2 headless screws and was immobilized in a plaster cast for 6 weeks. In patient 2 (9 years old), because of the small size of the avulsed fragment, fixation was not possible. A modified Gould-Broström procedure was undertaken, facilitating repair of the avulsed fragment using anchor sutures. Copyright © 2016 American College of Foot and Ankle Surgeons. Published by Elsevier Inc. All rights reserved.

  10. A Contemporary Definition of Hip Dysplasia and Structural Instability: Toward a Comprehensive Classification for Acetabular Dysplasia.

    PubMed

    Wilkin, Geoffrey P; Ibrahim, Mazen M; Smit, Kevin M; Beaulé, Paul E

    2017-09-01

    Hip dysplasia has long been known to be a risk factor for pain and degenerative changes in the hip joint. The diagnosis of dysplasia has historically been based on assessments of acetabular anatomy on the anteroposterior pelvic radiograph, most commonly the lateral center-edge angle. Recent advances in imaging of the dysplastic hip with computerized tomography scans have demonstrated that hip dysplasia is in fact a 3-dimensional (D) deformity of the acetabulum and that multiple patterns of hip instability exist that may not be completely assessed on 2D imaging. A more thorough understanding of acetabular anatomy permits an evolution away from vague terms such as "borderline dysplasia." A 3D assessment of the acetabulum and the resultant patterns of instability may be more appropriate since this would allow more accurate treatment to correct the structural instability with acetabular reorientation. With this information, we propose a diagnostic framework that groups symptomatic dysplastic hips into one of 3 categories based on the primary direction of instability: (1) anterior, (2) posterior, and (3) global. This framework may aid the clinician in developing a differential diagnosis for the assessment of hip pain and suspected instability, and for planning an appropriate surgical management. Copyright © 2017 Elsevier Inc. All rights reserved.

  11. Extra-Articular Lateral Tenodesis for Anterior Cruciate Ligament Deficient Knee: A Case Report

    PubMed Central

    García-Germán, Diego; Menéndez, Pablo; de la Cuadra, Pablo; Rodríguez-Arozena, Ricardo

    2013-01-01

    We present the case of an extra-articular lateral tenodesis for an anterior cruciate ligament (ACL) deficient knee. A 46-year-old male patient sustained an ACL graft rupture after a motorcycle accident. He complained of rotational instability and giving-way episodes. His previous graft was fixed by an intra-articular femoral staple that was not possible to remove at the time of the ACL revision. A modified Lemaire procedure was then performed. He gained rotational stability and was able to resume his sporting activities. We believe that isolated extra-articular reconstructions may still have a role in selected indications including moderate-demand patients complaining of rotational instability after ACL graft failure. PMID:24369517

  12. Surgical versus nonsurgical treatment in first traumatic anterior dislocation of the shoulder in athletes

    PubMed Central

    Arliani, Gustavo Gonçalves; Astur, Diego da Costa; Cohen, Carina; Ejnisman, Benno; Andreoli, Carlos Vicente; De Castro Pochini, Alberto; Cohen, Moises

    2011-01-01

    Anterior traumatic dislocation is a common problem faced by orthopedic surgeons. After the first episode of shoulder dislocation, a combination of lesions can lead to chronic instability. The management in treatment of young athletes after the first acute anterior shoulder dislocation is controversial. The available literature supports early surgical treatment for young male athletes engaged in highly demanding physical activities after the first episode of traumatic dislocation of the shoulder. This is because of the best functional results and lower recurrence rates obtained with this treatment in this population. However, further clinical trials of good quality comparing surgical versus nonsurgical treatment for well-defined lesions are needed, especially for categories of patients who have a lower risk of recurrence. PMID:24198566

  13. Estrogens sensitize anterior pituitary gland to apoptosis.

    PubMed

    Pisera, D; Candolfi, M; Navarra, S; Ferraris, J; Zaldivar, V; Jaita, G; Castro, M G; Seilicovich, A

    2004-10-01

    Tissue homeostasis results from a balance between cell proliferation and cell death by apoptosis. Estradiol affects proliferation as well as apoptosis in hormone-dependent tissues. In the present study, we investigated the apoptotic response of the anterior pituitary gland to lipopolysaccharide (LPS) in cycling female rats, and the influence of estradiol in this response in ovariectomized (OVX) rats. The OVX rats were chronically estrogenized with implanted Silastic capsules containing 1 mg of 17beta-estradiol (E2). Cycling or OVX and E2-treated rats were injected with LPS (250 microg/rat ip). Apoptosis was determined by the terminal deoxynucleotidyl-mediated dUTP nick-end labeling (TUNEL) method in sections of the anterior pituitary gland and spleen. Chronic estrogenization induced apoptosis in the anterior pituitary gland. Acute endotoxemia triggered apoptosis of cells in the anterior pituitary gland of E2-treated rats but not of OVX rats. No differences were observed in the apoptotic response to LPS in spleen between OVX and E2-treated rats. The apoptotic response of the anterior pituitary to LPS was variable along the estrous cycle, being higher at proestrus than at estrus or diestrus I. Approximately 75% of the apoptotic cells were identified as lactotropes by immunofluorescence. In conclusion, our results indicate that estradiol induces apoptosis and enables the proapoptotic action of LPS in the anterior pituitary gland. Also, our study suggests that estrogens may be involved in anterior pituitary cell renewal during the estrous cycle, sensitizing lactotropes to proapoptotic stimuli.

  14. Knee stability assessment on anterior cruciate ligament injury: Clinical and biomechanical approaches

    PubMed Central

    Lam, Mak-Ham; Fong, Daniel TP; Yung, Patrick SH; Ho, Eric PY; Chan, Wood-Yee; Chan, Kai-Ming

    2009-01-01

    Anterior cruciate ligament (ACL) injury is common in knee joint accounting for 40% of sports injury. ACL injury leads to knee instability, therefore, understanding knee stability assessments would be useful for diagnosis of ACL injury, comparison between operation treatments and establishing return-to-sport standard. This article firstly introduces a management model for ACL injury and the contribution of knee stability assessment to the corresponding stages of the model. Secondly, standard clinical examination, intra-operative stability measurement and motion analysis for functional assessment are reviewed. Orthopaedic surgeons and scientists with related background are encouraged to understand knee biomechanics and stability assessment for ACL injury patients. PMID:19712449

  15. C1 anterior arch preservation in transnasal odontoidectomy using three-dimensional endoscope: A case report

    PubMed Central

    Zenga, Francesco; Marengo, Nicola; Pacca, Paolo; Pecorari, Giancarlo; Ducati, Alessandro

    2015-01-01

    Background: The transoral ventral corridor is the most common approach used to reach the craniovertebral junction (CVJ). Over the last decade, many case reports have demonstrated the transnasal corridor to the odontoid peg represents a practicable route to remove the tip of the odontoid process. The biomechanical consequences of the traditional odontoidectomy led to the necessity of a cervical spine stabilization. Preserving the inferior portion of the C1 anterior arch should prevent instability. Case Description: This is the first report in which the technique to remove the tip of the odontoid while preserving the C1 anterior arch is described by means of a three-dimensional (3D) endoscope. A 53-year-old man underwent a transnasal 3D endoscopic approach because of a complex CVJ malformation. The upper-medial portion of the C1 anterior arch was removed preserving its continuity, and the odontoidectomy was performed. After surgery, a dynamic X-ray scan showed no difference in CVJ motility in comparison with the preoperative one. Conclusions: The stereoscopic perception augmented the precision of the surgical gesture in the deep field. The importance of a 3D view relates to the depth of field, which a two-dimensional endoscopy cannot provide. This affects the preservation of the C1 anterior arch because of the presence of critical structures that are exposed to potential damage if not displayed. PMID:26759737

  16. Healing of the Acutely Injured Anterior Cruciate Ligament: Functional Treatment with the ACL-Jack, a Dynamic Posterior Drawer Brace

    PubMed Central

    Reischl, Nikolaus; Rönn, Karolin; Magnusson, Robert A.; Gautier, Emanuel; Jakob, Roland P.

    2016-01-01

    Background. The injured anterior cruciate ligament (ACL) has a limited healing capacity leading to persisting instability. Hypothesis/Purpose. To study if the application of a brace, producing a dynamic posterior drawer force, after acute ACL injury reduces initial instability. Study Design. Cohort study. Methods. Patients treated with the ACL-Jack brace were compared to controls treated with primary ACL reconstruction und controls treated nonsurgically with functional rehabilitation. Measurements included anterior laxity (Rolimeter), clinical scores (Lysholm, Tegner, and IKDC), and MRI evaluation. Patients were followed up to 24 months. Results. Patients treated with the ACL-Jack brace showed a significant improvement of anterior knee laxity comparable to patients treated with ACL reconstruction, whereas laxity persisted after nonsurgical functional rehabilitation. The failure risk (secondary reconstruction necessary) of the ACL-Jack group was however 21% (18 of 86) within 24 months. Clinical scores were similar in all treatment groups. Conclusion. Treatment of acute ACL tears with the ACL-Jack brace leads to improved anterior knee laxity compared to nonsurgical treatment with functional rehabilitation. PMID:28053787

  17. Healing of the Acutely Injured Anterior Cruciate Ligament: Functional Treatment with the ACL-Jack, a Dynamic Posterior Drawer Brace.

    PubMed

    Jacobi, Matthias; Reischl, Nikolaus; Rönn, Karolin; Magnusson, Robert A; Gautier, Emanuel; Jakob, Roland P

    2016-01-01

    Background. The injured anterior cruciate ligament (ACL) has a limited healing capacity leading to persisting instability. Hypothesis/Purpose. To study if the application of a brace, producing a dynamic posterior drawer force, after acute ACL injury reduces initial instability. Study Design. Cohort study. Methods. Patients treated with the ACL-Jack brace were compared to controls treated with primary ACL reconstruction und controls treated nonsurgically with functional rehabilitation. Measurements included anterior laxity (Rolimeter), clinical scores (Lysholm, Tegner, and IKDC), and MRI evaluation. Patients were followed up to 24 months. Results. Patients treated with the ACL-Jack brace showed a significant improvement of anterior knee laxity comparable to patients treated with ACL reconstruction, whereas laxity persisted after nonsurgical functional rehabilitation. The failure risk (secondary reconstruction necessary) of the ACL-Jack group was however 21% (18 of 86) within 24 months. Clinical scores were similar in all treatment groups. Conclusion. Treatment of acute ACL tears with the ACL-Jack brace leads to improved anterior knee laxity compared to nonsurgical treatment with functional rehabilitation.

  18. Comparison of Time to Recurrence of Instability After Open and Arthroscopic Bankart Repair Techniques

    PubMed Central

    Virk, Mandeep S.; Manzo, Richard L.; Cote, Mark; Ware, James K.; Mazzocca, Augustus D.; Nissen, Carl W.; Shea, Kevin P.; Arciero, Robert A.

    2016-01-01

    Background: The results of open and arthroscopic instability repairs have been shown to be equivalent in recent literature. Purpose: To compare the time to recurrence (TTR) of instability and disease-specific outcome measures in patients undergoing open and arthroscopic Bankart repair. Study Design: Cohort study; Level of evidence, 3. Methods: Patients with recurrent traumatic anterior shoulder instability and a Bankart lesion on diagnostic arthroscopy underwent either open Bankart repair (OB) or arthroscopic Bankart and suture capsulorrhaphy (ABSC) using suture anchors. There was a minimum follow-up of 24 months. The primary outcome measures included Western Ontario Shoulder Instability Index (WOSI) score and time to recurrence of instability (dislocation or subluxation). Rowe score, Simple Shoulder Test, Constant score, American Shoulder and Elbow Surgeons (ASES) score, and Short Form–12 (SF-12) score were also compared. Results: A total of 82 shoulders in 80 patients (ABSC, n = 58; OB, n = 24) were evaluated at a mean of 39 months postoperatively. There were 4 clinical failures in the OB group (4 dislocations) and 7 clinical failures in the ABSC group (2 dislocations and 5 subluxations; P = .72 vs OB). The mean time to recurrence of postoperative instability was significantly shorter in the ABSC group (12.6 ± 2.7 months) compared with the OB group (34.2 ± 12 months; P = .04). The WOSI score in the OB group (265 ± 48.1) was better but not statistically significantly compared with the ABSC group (449.8 ± 63.8; P = .06). Conclusion: The time to recurrence of instability after open Bankart repair is significantly longer compared with arthroscopic Bankart repair. Clinical Relevance: Delayed time to recurrence after open Bankart repair suggests that the open technique may be more suited to withstand the high stress and demands of a heavy-duty profession (contact athletes and heavy manual labor). PMID:27570783

  19. Comparison of Time to Recurrence of Instability After Open and Arthroscopic Bankart Repair Techniques.

    PubMed

    Virk, Mandeep S; Manzo, Richard L; Cote, Mark; Ware, James K; Mazzocca, Augustus D; Nissen, Carl W; Shea, Kevin P; Arciero, Robert A

    2016-06-01

    The results of open and arthroscopic instability repairs have been shown to be equivalent in recent literature. To compare the time to recurrence (TTR) of instability and disease-specific outcome measures in patients undergoing open and arthroscopic Bankart repair. Cohort study; Level of evidence, 3. Patients with recurrent traumatic anterior shoulder instability and a Bankart lesion on diagnostic arthroscopy underwent either open Bankart repair (OB) or arthroscopic Bankart and suture capsulorrhaphy (ABSC) using suture anchors. There was a minimum follow-up of 24 months. The primary outcome measures included Western Ontario Shoulder Instability Index (WOSI) score and time to recurrence of instability (dislocation or subluxation). Rowe score, Simple Shoulder Test, Constant score, American Shoulder and Elbow Surgeons (ASES) score, and Short Form-12 (SF-12) score were also compared. A total of 82 shoulders in 80 patients (ABSC, n = 58; OB, n = 24) were evaluated at a mean of 39 months postoperatively. There were 4 clinical failures in the OB group (4 dislocations) and 7 clinical failures in the ABSC group (2 dislocations and 5 subluxations; P = .72 vs OB). The mean time to recurrence of postoperative instability was significantly shorter in the ABSC group (12.6 ± 2.7 months) compared with the OB group (34.2 ± 12 months; P = .04). The WOSI score in the OB group (265 ± 48.1) was better but not statistically significantly compared with the ABSC group (449.8 ± 63.8; P = .06). The time to recurrence of instability after open Bankart repair is significantly longer compared with arthroscopic Bankart repair. Delayed time to recurrence after open Bankart repair suggests that the open technique may be more suited to withstand the high stress and demands of a heavy-duty profession (contact athletes and heavy manual labor).

  20. Knee motion variability in patients with knee osteoarthritis: the effect of self-reported instability

    PubMed Central

    Gustafson, Jonathan A.; Robinson, Megan E.; Fitzgerald, G. Kelley; Tashman, Scott; Farrokhi, Shawn

    2015-01-01

    Background Knee osteoarthritis has been previously associated with a stereotypical knee-stiffening gait pattern and reduced knee joint motion variability due to increased antagonist muscle co-contractions and smaller utilized arc of motion during gait. However, episodic self-reported instability may be a sign of excessive motion variability for a large subgroup of patients with knee osteoarthritis. The objective of this work was to evaluate the differences in knee joint motion variability during gait in patients with knee osteoarthritis with and without self-reported instability compared to a control group of older adults with asymptomatic knees. Methods Forty-three subjects, 8 with knee osteoarthritis but no reports of instability (stable), 11 with knee osteoarthritis and self-reported instability (unstable), and 24 without knee osteoarthritis or instability (control) underwent Dynamic Stereo X-ray analysis during a decline gait task on a treadmill. Knee motion variability was assessed using parametric phase plots during the loading response phase of decline gait. Findings The stable group demonstrated decreased sagittal-plane motion variability compared to the control group (p=0.04), while the unstable group demonstrated increased sagittal-plane motion variability compared to the control (p=0.003) and stable groups (p<0.001). The unstable group also demonstrated increased anterior-posterior joint contact point motion variability for the medial tibiofemoral compartment compared to the control (p=0.03) and stable groups (p=0.03). Interpretation The finding of decreased knee motion variability in patients with knee osteoarthritis without self-reported instability supports previous research. However, presence of self-reported instability is associated with increased knee motion variability in patients with knee osteoarthritis and warrants further investigation. PMID:25796536

  1. A Comparison between Clinical Results of Selective Bundle and Double Bundle Anterior Cruciate Ligament Reconstruction

    PubMed Central

    Yoo, Yon-Sik; Song, Si Young; Yang, Cheol Jung; Ha, Jong Mun; Kim, Yoon Sang

    2016-01-01

    Purpose The purpose of this study was to compare the clinical outcomes of arthroscopic anatomical double bundle (DB) anterior cruciate ligament (ACL) reconstruction with either selective anteromedial (AM) or posterolateral (PL) bundle reconstruction while preserving a relatively healthy ACL bundle. Materials and Methods The authors evaluated 98 patients with a mean follow-up of 30.8±4.0 months who had undergone DB or selective bundle ACL reconstructions. Of these, 34 cases underwent DB ACL reconstruction (group A), 34 underwent selective AM bundle reconstruction (group B), and 30 underwent selective PL bundle reconstructions (group C). These groups were compared with respect to Lysholm and International Knee Documentation Committee (IKDC) score, side-to-side differences of anterior laxity measured by KT-2000 arthrometer at 30 lbs, and stress radiography and Lachman and pivot shift test results. Pre- and post-operative data were objectively evaluated using a statistical approach. Results The preoperative anterior instability measured by manual stress radiography at 90° of knee flexion in group A was significantly greater than that in groups B and C (all p<0.001). At last follow-up, mean side-to-side instrumented laxities measured by the KT-2000 and manual stress radiography were significantly improved from preoperative data in all groups (all p<0.001). There were no significant differences between the three groups in anterior instability measured by KT-2000 arthrometer, pivot shift, or functional scores. Conclusion Selective bundle reconstruction in partial ACL tears offers comparable clinical results to DB reconstruction in complete ACL tears. PMID:27401652

  2. The anterior open bite problem (infraclusion).

    PubMed

    Champagne, M

    1995-06-01

    Anterior open bite is a major orthodontic problem that is very difficult to treat (Fig. 1). It may not be the most frequent problem but it is a major functional problem. Quite often it is very difficult to correct an anterior open bite problem and even more difficult to treat in an adult after growth. Most of the time anterior open bite is a myofunctional problem related to a bad habit like thumb or finger sucking and/or is related to a breathing and swallowing problem. How can we understand the functional open bite problem? What are the available treatment options? This article will try to answer some of these questions.

  3. Mini-open anterior lumbar interbody fusion.

    PubMed

    Gandhoke, Gurpreet S; Ricks, Christian; Tempel, Zachary; Zuckerbraun, Brian; Hamilton, D Kojo; Okonkwo, David O; Kanter, Adam S

    2016-07-01

    In deformity surgery, anterior lumbar interbody fusion provides excellent biomechanical support, creates a broad surface area for arthrodesis, and induces lordosis in the lower lumbar spine. Preoperative MRI, plain radiographs, and, when available, CT scan should be carefully assessed for sacral slope as it relates to pubic symphysis, position of the great vessels (especially at L4/5), disc space height, or contraindication to an anterior approach. This video demonstrates the steps in an anterior surgical procedure with minimal open exposure. The video can be found here: https://youtu.be/r3bC4_vu1hQ .

  4. High Prevalence of Cervical Deformity and Instability Requires Surveillance in Loeys-Dietz Syndrome

    PubMed Central

    Fuhrhop, Sara K.; McElroy, Mark J.; Dietz, Harry C.; MacCarrick, Gretchen L.; Sponseller, Paul D.

    2015-01-01

    Background: Loeys-Dietz syndrome is a connective tissue disorder characterized by vascular, craniofacial, and musculoskeletal malformation. Our goal was to report the manifestations, surgical treatment, and complications in the cervical spine in patients with Loeys-Dietz syndrome. Methods: We reviewed the clinical and cervical spine imaging data of eighty patients with Loeys-Dietz syndrome who were seen at our institution from January 2005 through January 2014. Their mean age at presentation was 17.3 years (range, three months to seventy-five years). We tested associations with use of the Fisher exact test (type of TGF-βR [transforming growth factor-beta receptor] mutation and cervical abnormalities) and the Student t test (age at presentation and type of TGF-βR mutation) (significance, p = 0.05). Results: Vertebral anomalies and cervical instability were common; we found no significant association of TGF-βR-type with cervical abnormalities or age at presentation. Twenty-eight patients had atlas defects (anterior and/or posterior arch defects or hypoplasia), fifty-three had axis malformations (elongation, apex-anterior dens angulation, or spondylolysis), and twelve had focal kyphosis. Ten patients had hypoplastic subaxial vertebrae, leading to focal kyphosis (eight) and subaxial instability (nine). Eight patients had atlantoaxial instability. Of the thirteen patients with cervical instability, nine were treated surgically: fusion (eight patients) and halo application (one) (mean age, four years; range, three months to twelve years). Postoperative complications (seven patients) were pseudarthrosis, failure of fixation, junctional kyphosis or instability, and development of occipital-cervical instability. Conclusions: Cervical midline defects (most often C1-C3) are common in Loeys-Dietz syndrome. Patients have a high prevalence of cervical instability, particularly a pattern of instability at C2-C3 associated with C3 vertebral body hypoplasia and C2-C3 focal

  5. Long Term Outcomes of Arthroscopic Shoulder Instability Surgery

    PubMed Central

    Karataglis, D.; Agathangelidis, F.

    2017-01-01

    Background: Anterior shoulder instability has been successfully managed arthroscopically over the past two decades with refined “anatomic” reconstruction procedures involving the use of anchors for the repositioning and re-tensioning of the antero-inferior capsuloligamentous complex, in an effort to recreate its “bumper effect”. Methods: Research and online content related to arthroscopic treatment of shoulder instability was reviewed and their results compared. Results: The short- and mid-term results of this technique have been very satisfactory. The greatest number of recent reports suggests that long-term results (>5 years follow-up) remain rather satisfactory, especially in the absence of significant glenoid bone loss (>20-25%). In these studies recurrent instability, in the form of either dislocation or subluxation, ranges from 5.1 to over 20%, clinical scores, more than 5 years after the index procedure, remain good or excellent in >80% of patient population as do patient satisfaction and return to previous level of activities. As regards arthroscopic non-anatomic bony procedures (Latarjet or Bristow procedures) performed in revision cases or in the presence of >20-25% bone loss of the anteroinferior aspect of the glenoid, recent reports suggest that their long-term results are very satisfactory both in terms of re-dislocation rates and patient satisfaction. Conclusion: It appears that even “lege artis” performance of arthroscopic reconstruction decelerates but does not obliterate the degenerative procedure of dislocation arthropathy. The presence and grade of arthritic changes correlate with the number of dislocations sustained prior to the arthroscopic intervention, the number of anchors used and the age at initial dislocation and surgery. However, the clinical significance of radiologically evident dislocation arthropathy is debatable. PMID:28400881

  6. Impact of obesity in elderly patients with postural instability.

    PubMed

    Rossi-Izquierdo, Marcos; Santos-Pérez, Sofía; Faraldo-García, Ana; Vaamonde-Sánchez-Andrade, Isabel; Gayoso-Diz, Pilar; Del-Río-Valeiras, María; Lirola-Delgado, Antonio; Soto-Varela, Andrés

    2016-06-01

    The aim of the study is to assess whether obesity affects balance in elderly patients with postural instability. It is a case-control study, with cases defined by BMI ≥30 kg/m(2), and developed in a third level university hospital. We included 135 patients aged 65 years old or more who presented postural instability. Balance assessment was through the sensory organisation test (SOT), limits of stability (LOS) and rhythmic weight shift (RWS) of computerised dynamic posturography (CDP) and the modified timed up-and-go (TUG) test. The patients also completed the Dizziness Handicap Inventory and short Falls Efficacy Scale-International questionnaire. Patients with obesity took longer to perform the modified TUG and required more steps. Also these patients had poorer scores in the subjective tests. In the CDP there were no significant differences in the SOT nor the LOS, and only there was a statistical significant difference in the anterior-posterior directional control of the RWS. Obese patients have a higher risk of fallings compared to non-obese patients. In essence, our results indicate that obesity interferes in the balance of elderly patients with postural instability, putting them at a greater risk of fallings, performing worse dynamic tasks and feeling more disabled. Although continued education on training balance may be useful in older population, since the obese group shows more rate of fallers, rehabilitation programmes focus on dynamic tasks in these patients could be useful to reduce their fall risk and improve their quality of life.

  7. How I do it: Anterior pull-through tympanoplasty for anterior eardrum perforations.

    PubMed

    Harris, Jeffrey P; Wong, Yu-Tung; Yang, Tzong-Hann; Miller, Mia

    2016-01-01

    Conclusions This technique is offered as a convenient and reliable method for cases with anterior TM perforation and inadequate anterior remnant. Objectives Chronic otitis media surgery is one of the most common procedures in otology. Anterior tympanic membrane (TM) perforation with inadequate anterior remnant is associated with higher rates of graft failure. It was the goal of this series to evaluate the anatomical and functional outcomes of a modified underlay myringoplasty technique-the anterior pull-through method. Materials and methods In a retrospective clinical study, 13 patients with anterior TM perforations with inadequate anterior remnants underwent tympanoplasty with anterior pull-through technique. The anterior tip of the temporalis fascia was pulled through and secured in a short incision lateral to the anterior part of the annulus. Data on graft take rate, pre-operative, and post-operative hearing status were analyzed. Results A graft success rate of 84.6% (11 out of 13) was achieved, without lateralization, blunting, atelectasia, or epithelial pearls. The air-bone gap was 21.5 ± 6.8 dB before intervention and 11.75 ± 5.7 dB after surgery (p = 0.003).

  8. A Radiological Comparison of Anterior Fusion Rates in Anterior Lumbar Interbody Fusion

    PubMed Central

    McCarthy, M. J. H.; Ng, L.; Vermeersch, G.; Chan, D.

    2012-01-01

    Aim To compare anterior fusion in standalone anterior lumbar interbody fusion (ALIF) using cage and screw constructs and anterior cage–alone constructs with posterior pedicle screw supplementation but without posterior fusion. Methods Eighty-five patients underwent single- or two-level ALIF procedure for degenerative disk disease or lytic spondylolisthesis (SPL). Posterior instrumentation was performed without posterior fusion in all cases of lytic SPL and when the anterior cage used did not have anterior screw through cage fixation. Results Seventy (82%) patients had adequate radiological follow-up at a mean of 19 months. Forty patients had anterior surgery alone (24 single level and 16 two levels) and 30 had front-back surgery (15 single level and 15 two levels). Anterior locked pseudarthrosis was only seen in the anterior surgery–alone group when using the STALIF cage (Surgicraft, Worcestershire, UK) (37 patients). This occurred in five of the single-level surgeries (5/22) and nine of the two-level surgeries (9/15). Fusion was achieved in 100% of the front-back group and only 65% (26/40) of the anterior surgery–alone group. Conclusion Posterior pedicle screw supplementation without posterolateral fusion improves the fusion rate of ALIF when using anterior cage and screw constructs. We would recommend supplementary posterior fixation especially in cases where more than one level is being operated. PMID:24353968

  9. Benzodiazepines and anterior pituitary function.

    PubMed

    Arvat, E; Giordano, R; Grottoli, S; Ghigo, E

    2002-09-01

    its role in the neuroendocrine control of anterior pituitary function; their usefulness probably overrides what had been supposed before.

  10. Nonarteritic anterior ischemic optic neuropathy.

    PubMed

    Atkins, Edward J

    2011-02-01

    Currently there is no generally accepted, well-proven treatment for nonarteritic anterior ischemic optic neuropathy (NAION). Most proposed treatments are empirical and include antithrombotics, vasodynamic agents, treatments aimed at reducing optic disc edema, and various neuroprotective strategies. Most potential treatments have been inadequately studied, prematurely embraced, or prematurely discarded. Evidence for antithrombotic agents is lacking, and small vessel arterial occlusion has never been demonstrated in NAION. Antiplatelet agents have not been studied in acute NAION, but they are often prescribed for acute treatment because of their proven role in stroke prevention. Because NAION is an ischemic disorder occurring more often after the age of 50 in patients with vascular risk factors, I recommend aggressive risk-factor management and antiplatelet therapy. The evidence that aspirin can help to prevent NAION in the fellow eye is divided. I recommend aspirin for secondary prevention, mostly for its proven role in stroke prevention. NAION occurs in patients with physiologically crowded optic nerves and small cup-to-disc ratios. Disc edema may contribute to a "compartment syndrome," which compresses the fine capillary blood supply of the optic nerve head, resulting in ischemia and axonal damage. There is some limited and debatable evidence that oral steroids may shorten the duration of disc edema and improve visual outcome in NAION. I discuss this evidence with patients who present acutely with NAION, and although I consider prescribing oral steroids on a case-by-case basis, I will not routinely recommend oral steroids until a properly randomized clinical trial is performed. Some neuroprotective strategies have been studied, but none have proven to be helpful. Although some (eg, brimonidine) are probably not harmful, I do not recommend these treatments. Early referral to low vision services may help to improve functional visual outcome.

  11. Finite Element Analysis of Patella Alta: A Patellofemoral Instability Model.

    PubMed

    Watson, Nicole A; Duchman, Kyle R; Grosland, Nicole M; Bollier, Matthew J

    2017-01-01

    This study aims to provide biomechanical data on the effect of patella height in the setting of medial patellofemoral ligament (MPFL) reconstruction using finite element analysis. The study will also examine patellofemoral joint biomechanics using variable femoral insertion sites for MPFL reconstruction. A previously validated finite element knee model was modified to study patella alta and baja by translating the patella a given distance to achieve each patella height ratio. Additionally, the models were modified to study various femoral insertion sites of the MPFL (anatomic, anterior, proximal, and distal) for each patella height model, resulting in 32 unique scenarios available for investigation. In the setting of patella alta, the patellofemoral contact area decreased, resulting in a subsequent increase in maximum patellofemoral contact pressures as compared to the scenarios with normal patellar height. Additionally, patella alta resulted in decreased lateral restraining forces in the native knee scenario as well as following MPFL reconstruction. Changing femoral insertion sites had a variable effect on patellofemoral contact pressures; however, distal and anterior femoral tunnel malpositioning in the setting of patella alta resulted in grossly elevated maximum patellofemoral contact pressures as compared to other scenarios. Patella alta after MPFL reconstruction results in decreased lateral restraining forces and patellofemoral contact area and increased maximum patellofemoral contact pressures. When the femoral MPFL tunnel is malpositioned anteriorly or distally on the femur, the maximum patellofemoral contact pressures increase with severity of patella alta. When evaluating patients with patellofemoral instability, it is important to recognize patella alta as a potential aggravating factor. Failure to address patella alta in the setting of MPFL femoral tunnel malposition may result in even further increases in patellofemoral contact pressures, making it

  12. Finite Element Analysis of Patella Alta: A Patellofemoral Instability Model

    PubMed Central

    Duchman, Kyle R.; Grosland, Nicole M.; Bollier, Matthew J.

    2017-01-01

    Abstract Background: This study aims to provide biomechanical data on the effect of patella height in the setting of medial patellofemoral ligament (MPFL) reconstruction using finite element analysis. The study will also examine patellofemoral joint biomechanics using variable femoral insertion sites for MPFL reconstruction. Methods: A previously validated finite element knee model was modified to study patella alta and baja by translating the patella a given distance to achieve each patella height ratio. Additionally, the models were modified to study various femoral insertion sites of the MPFL (anatomic, anterior, proximal, and distal) for each patella height model, resulting in 32 unique scenarios available for investigation. Results: In the setting of patella alta, the patellofemoral contact area decreased, resulting in a subsequent increase in maximum patellofemoral contact pressures as compared to the scenarios with normal patellar height. Additionally, patella alta resulted in decreased lateral restraining forces in the native knee scenario as well as following MPFL reconstruction. Changing femoral insertion sites had a variable effect on patellofemoral contact pressures; however, distal and anterior femoral tunnel malpositioning in the setting of patella alta resulted in grossly elevated maximum patellofemoral contact pressures as compared to other scenarios. Conclusions: Patella alta after MPFL reconstruction results in decreased lateral restraining forces and patellofemoral contact area and increased maximum patellofemoral contact pressures. When the femoral MPFL tunnel is malpositioned anteriorly or distally on the femur, the maximum patellofemoral contact pressures increase with severity of patella alta. Clinical Relevance: When evaluating patients with patellofemoral instability, it is important to recognize patella alta as a potential aggravating factor. Failure to address patella alta in the setting of MPFL femoral tunnel malposition may result in

  13. Microscale instabilities in stream interaction regions

    NASA Technical Reports Server (NTRS)

    Eviatar, A.; Goldstein, M. L.

    1979-01-01

    The microstructure of solar wind stream interaction regions is considered theoretically with emphasis on the role of several electrostatic kinetic instabilities which may be important within the stream interface and the compression region. Inside of 1 AU, the interface is likely to be stable against the electrostatic streaming instabilities considered. Between 1 and 2 AU, the interface will excite the magnetized ion-ion instability. The compression region is also found to be unstable beyond 1 AU where the modified two-stream instability, beam-cyclotron instability, and ion-acoustic instability are important in determining the structure of the compressive pulses as they evolve into forward and reverse shocks. It is concluded that the modified two-stream instability and beam-cyclotron instability predominately play a role in heating the electrons to the threshold for the ion-acoustic instability. Various electrostatic plasma waves, ranging in frequency from the lower-hybrid to harmonics of the electron cyclotron frequency, would be produced by these instabilities. Their signature should also be seen by high time resolution measurements of the temperature of the various plasma species.

  14. Two-Stage Revision Anterior Cruciate Ligament Reconstruction.

    PubMed

    Erickson, Brandon J; Cvetanovich, Gregory; Waliullah, Khalid; Khair, Michael; Smith, Patrick; Bach, Bernard; Sherman, Seth

    2016-05-01

    The number of primary anterior cruciate ligament (ACL) tears is rapidly increasing. In patients who wish to return to their preoperative level of function, specifically as it pertains to participation in sports, the gold standard of treatment following an ACL tear remains an anterior cruciate ligament (ACL) reconstruction. Despite a majority of good/excellent results following primary ACL reconstruction, there is a growing subset of patients with persistent or recurrent functional instability who require revision ACL reconstruction. Preoperative planning for revision ACL reconstruction requires a careful understanding of the root cause of ACL failure, including possible technical causes of primary ACL failure and the presence of combined knee pathology that was not addressed at the index ACL reconstruction. The decision to perform 2-stage revision ACL reconstruction is multifactorial and is reached by technical considerations that may make a 1-stage revision less optimal, including tunnel widening, arthrofibrosis, active infection, and others. Concomitant knee pathology such as meniscal deficiency, malalignment (including an increase in posterior tibial slope), chondral lesions, and other ligamentous laxity may also require a staged approach to treatment. This evidence-based review covers the indications for 2-stage revision ACL reconstruction, surgical techniques, evidence for and technique of bone grafting prior ACL tunnels, and outcomes of 2-stage revision stratified by initial cause of ACL reconstruction failure. With proper preoperative planning and an understanding of the cause of failure following the primary ACL reconstruction, revision ACL reconstruction can offer excellent outcomes in the motivated patient. [Orthopedics. 2016; 39(3):e456-e464.].

  15. C2-C3 Anterior Cervical Fusion: Technical Report.

    PubMed

    Finn, Michael A; MacDonald, Joel D

    2016-12-01

    Retrospective review of patients at a university hospital. To describe the anterior approach for cervical discectomy and fusion (ACDF) at C2-C3 level and evaluate its suitability for treatment of instability and degenerative disease in this region. The anterior approach is commonly used for ACDF in the lower cervical spine but is used less often in the high cervical spine. We retrospectively reviewed a database of consecutive cervical spine surgeries performed at our institution to identify patients who underwent ACDF at the C2-C3 level during a 10-year period. Demographic data, clinical indications, surgical technique, complications, and immediate results were evaluated. Of the 11 patients (7 female, 4 male; mean age 46 y) identified, 7 were treated for traumatic fractures and 4 for degenerative disk disease. Three patients treated for myelopathy showed improvement in mean Nurick grade from 3.6 to 1.3. Pain was significantly improved in all patients who had preoperative pain. Solid bony fusion was achieved in 5 of 7 patients at 3-month follow-up. Complications included dysphagia in 4 patients (which resolved in 3), aspiration pneumonia, mild persistent dysphonia, and construct failure at C2 requiring posterior fusion. One patient died of a pulmonary embolism 2 weeks postoperatively. ACDF at the C2-C3 level is an option for the treatment of high cervical disease or trauma but is associated with a higher rate of approach-related morbidity. Familiarity with local anatomy may help to reduce complications. ACDF at C2-C3 appears to have a fusion rate similar to ACDF performed at other levels.

  16. The improvement of postural control in patients with mechanical ankle instability after lateral ankle ligaments reconstruction.

    PubMed

    Li, Hong-Yun; Zheng, Jie-Jiao; Zhang, Jian; Cai, Ye-Hua; Hua, Ying-Hui; Chen, Shi-Yi

    2016-04-01

    Lateral ankle sprain is the most common injury. A previous study demonstrated that patients with mechanical ankle instability suffered deficits in postural control, indicating that structural damage of the lateral ankle ligaments may produce a balance deficit. The purpose of this study was to confirm that lateral ligaments reconstruction could improve postural control in patients with mechanical ankle instability. A total of 15 patients were included in the study. Each patient had a history of an ankle sprain with persistent symptoms of ankle instability and a positive anterior drawer test and had been treated nonoperatively for at least 3 months. All patients were diagnosed with lateral ankle ligaments tear by ultrasonography and magnetic resonance imaging. They underwent arthroscopic debridement and open lateral ankle ligaments reconstruction with a modified Broström procedure. One day before and 6 months after the operation, all of the participants underwent single-limb postural sway tests. The anterior drawer test and the American Orthopedic Foot and Ankle Society scale score were used to evaluate the clinical results in these patients. At 6 months after the operation, with the patients' eyes closed, there was significantly decreased postural sway in the anteroposterior direction, the circumferential area, and the total path length on the operated ankles compared with those measurements before the operation. With eyes open, however, no difference was found in postural sway before and after the operation. Postural control was improved by reconstructing the lateral ligaments. IV.

  17. Robotic testing of proximal tibio-fibular joint kinematics for measuring instability following total knee arthroplasty.

    PubMed

    Barsoum, Wael K; Lee, Ho H; Murray, Trevor G; Colbrunn, Robb; Klika, Alison K; Butler, S; van den Bogert, Antonie J

    2011-01-01

    Pain secondary to instability in total knee arthroplasty (TKA) has been shown to be major cause of early failure. In this study, we focused on the effect of instability in TKA on the proximal tibio-fibular joint (PTFJ). We used a robotics model to compare the biomechanics of the PTFJ in the native knee, an appropriately balanced TKA, and an unbalanced TKA. The tibia (n = 5) was mounted to a six-degree-of-freedom force/torque sensor and the femur was moved by a robotic manipulator. Motion at the PTFJ was recorded with a high-resolution digital camera system. After establishing a neutral position, loading conditions were applied at varying flexion angles (0°, 30°, and 60°). These included: internal/external rotation (0 Nm, ±5 Nm), varus/valgus (0 Nm, ±10 Nm), compression (100 N, 700 N), and posterior drawer (0 N, 100 N). With respect to anterior displacement, external rotation had the largest effect (coefficient = 0.650; p < 0.0001). Polyethylene size as well as the interaction between polyethylene size and flexion consistently showed substantial anterior motion. Flexion and mid-flexion instability in TKA have been difficult to quantify. While tibio-femoral kinematics is the main aspect of TKA performance, the effects on adjacent tissues should not be overlooked. Our data show that PTFJ kinematics are affected by the balancing of the TKA. Copyright © 2010 Orthopaedic Research Society.

  18. Anterior cruciate ligament (ACL) injury -- aftercare

    MedlinePlus

    ... ACL injury - aftercare References Amy E, Micheo W. Anterior cruciate ligament tear. In: Frontera WR, Silver JK, Rizzo TD Jr, eds. Essentials of Physical Medicine and Rehabilitation . 2nd ed. St. Louis, MO: ...

  19. Anterior regeneration in the hemichordate Ptychodera flava

    PubMed Central

    Rychel, Amanda L.; Swalla, Billie J.

    2008-01-01

    Ptychodera flava is a hemichordate whose anterior structures regenerate reproducibly from posterior trunk pieces when amputated. We characterized the cellular processes of anterior regeneration with respect to programmed cell death and cell proliferation, following wound healing. We found scattered proliferating cells at day two of regeneration using a PCNA antibody. On day four, most proliferating cells were associated with the nerve tract under the epidermis, and on day six, a small proboscis derived from proliferated cells was regenerated, and a mouth had broken though the epidermis. TUNEL detected elevated levels of apoptosis in the endoderm that began furthest away from the region of wound healing, then moved anteriorly over eight days. Posterior to anterior apoptosis is likely to remove digestive endoderm for later differentiation of pharyngeal endoderm. We hypothesize that P. flava regeneration is nerve dependent and that remodeling in the gut endoderm plays an important role in regeneration. PMID:18924231

  20. Dynamic restraint capacity of the hamstring muscles has important functional implications after anterior cruciate ligament injury and anterior cruciate ligament reconstruction.

    PubMed

    Bryant, Adam L; Creaby, Mark W; Newton, Robert U; Steele, Julie R

    2008-12-01

    The purpose of this study was to investigate the relation between knee functionality of anterior cruciate ligament deficient (ACLD) and anterior cruciate ligament reconstruction (ACLR) patients and hamstring antagonist torque generated during resisted knee extension. Cross-sectional. Laboratory based. Male ACLD subjects (n=10) (18-35 y) and 27 matched males who had undergone ACLR (14 patella tendon [PT] grafts and 13 combined semitendinosus/gracilis tendon grafts). Not applicable. Knee functionality was rated (0- to 100-point scale) by using the Cincinnati Knee Rating System. Using electromyography data from the semitendinosus (ST) and biceps femoris muscles, we created a mathematical model to estimate the opposing torque generated by the hamstrings during isokinetic knee extension in 10 degrees intervals from 80 degrees to 10 degrees knee flexion. Pearson product-moment correlations revealed that more functional ACLD subjects generated significantly (P<.05) higher hamstring antagonist torque throughout knee extension. In contrast, more functional PT subjects produced significantly lower hamstring antagonist torque at 80 degrees to 70 degrees knee flexion, whereas no significant associations were found between hamstring antagonist torque and knee functionality for the ST/gracilis tendon subjects. An increased hamstring antagonist torque generated by the more functional ACLD subjects, reflective of increased hamstring contractile force, is thought to represent a protective mechanism to compensate for mechanical instability. The restoration of anterior knee stability through ACLR negates the need for augmented hamstring antagonist torque.

  1. Symmetry breaking and wake instabilities

    NASA Astrophysics Data System (ADS)

    Sengupta, Raja

    A numerical technique has been developed in the context of spatio-temporal stability analysis. The convective/absolute nature of instability determines the time-asymptotic response of a linearly unstable flow, either in the form an oscillator or in the form of a noise amplifier. This depends on the location of pinch point singularities of the dispersion relations obtained via linear stability analyses. A new and efficient approach to locate such singularities is presented. Local analyticity of the dispersion relations was exploited via the Cauchy-Riemann equations in a quasi-Newton's root- finding procedure employing numerical Jacobians. Initial guesses provided by temporal stability analyses have been shown to converge to the pinch points even in the presence of multiple saddle points for various Falkner- Skan wedge profiles. This effort was motivated by the phenomenon of spontaneous symmetry breaking in flow over a cone. At large enough incidence, a pair of vortices develop on the leeward side of the cone which eventually become asymmetric as the angle of attack is increased further. A conical, thin-layer Navier-Stokes solver was employed to investigate the effect of flowfield saddles in this process. The approximate factorization scheme incorporated in the solver was shown analytically to be symmetric to eliminate possible sources of asymmetry. Local grid resolution studies were performed to demonstrate the importance of correctly computing the leeside saddle point and the secondary separation and reattchment points. Topological studies of the flow field as it loses symmetry agreed well with previous qualitative experimental observations. However, the original goal of this study, to settle an ongoing controversy regarding the nature of the instability responsible for symmetry breaking, could not be realized due to computational inadequacy. It is conjectured that the process is governed by an absolute instability similar to that observed in a flow over a circular

  2. Microsatellite instability in prostate cancer

    SciTech Connect

    Shan, A.L.; Wick, M.J.; Persons, D.L.

    1994-09-01

    Microsatellite instability (MIN) has been documented in hereditary nonpolyposis colorectal cancer (HNPCC) as well as in sporadic forms of human cancers. Two of the genes which appear to be responsible for this particular tumor phenotype, hMSH2 and hMLH1, have now been identified. To determine the potential role of these mutator genes in prostate cancer, we have examined 95 prostate adenocarcinomas (40 paraffin embedded and 55 fresh frozen) for the presence of genetic instability at four microsatellite markers. The markers are localized to chromosome arms 5q(APC-CA1), 8p(Mfd 210Z), 15q(635/636), and 17q(p53-CA). Patients from whom paraffin embedded material was obtained were divided into short term (<3 years, n=18), and long term (>3 years, n=22) survivors. Of the 95 tumors examined, only four tumors (4%) demonstrated MIN: two tumors demonstrated MIN at 3 loci (p53-CA, APC-CA1, 635/636), one tumor demonstrated MIN at 2 loci (APC-CA1 and 635/636), and one tumor demonstrated instability at 635/636 only. All tumors exhibiting MIN had Gleason scores of {ge} 4+4. A correlation between MIN and survival was not observed. Information on family history was limited. However, of the two patients demonstrating MIN at three loci, one patient was diagnosed with a second malignancy (TCC of the ureter), but otherwise had a negative family history, while the second patient had one first degree relative with esophageal cancer. The patient demonstrating MIN at two loci had a negative family history, while the remaining patient had two first degree relatives with cancer (prostate and stomach). These results suggest that hMSH2 and hMLH1 (as reflected by the small percentage of tumors displaying MIN) do not play a prominent role in the process of prostate tumorigenesis.

  3. Microbunch Instability Theory and Simulations

    SciTech Connect

    Stupakov, G.

    2005-01-26

    Over the last years there have been several reports of quasiperiodic bursts of coherent synchrotron radiation (CSR) in electron rings in the microwave and far-infrared range. The observations were made on synchrotron radiation light sources which include the Synchrotron Ultraviolet Radiation Facility SURF II [1], the VUV ring at the National Synchrotron Light Source at BNL [2, 3], second generation light sources MAX-I [4], BESSY II [5], and ALS [6]. General features of those observations can be summarized as follows. Above a threshold current, there is a strongly increased radiation of the beam in the range of wavelengths shorter than the bunch length, {lambda} < {sigma}{sub 2}. At large currents, this radiation is observed as a sequence of random bursts. In the bursting regime, intensity of the radiation scales approximately as square of the number of particles in the bunch, indicating a coherent nature of the phenomenon. It is generally accepted that the source of this radiation is related to the microbunching of the beam arising from development of a microwave instability caused by the coherent synchrotron radiation of the beam. A relativistic electron beam moving in a circular orbit in free space can radiate coherently if the wavelength of the synchrotron radiation exceeds the length of the bunch. In accelerators coherent radiation of the bunch is usually suppressed by the shielding effect of the conducting walls of the vacuum chamber [7-9], which gives an exponential cutoff of wavelengths greater than a certain threshold. However, an initial density fluctuation with a characteristic length much shorter than the shielding threshold would radiate coherently. If the radiation reaction force is such that it results in the growth of the initial fluctuation one can expect an instability that leads to micro-bunching of the beam and an increased coherent radiation at short wavelengths. A possibility of CSR instability was pointed out in Refs. [10, 11].

  4. Risk bubbles and market instability

    NASA Astrophysics Data System (ADS)

    Marsili, Matteo; Raffaelli, Giacomo

    2006-10-01

    We discuss a simple model of correlated assets capturing the feedback effects induced by portfolio investment in the covariance dynamics. This model predicts an instability when the volume of investment exceeds a critical value. Close to the critical point the model exhibits dynamical correlations very similar to those observed in real markets. Maximum likelihood estimates of the model's parameter for empirical data indeed confirms this conclusion. We show that this picture is confirmed by the empirical analysis for different choices of the time horizon.

  5. Convective Instabilities in Liquid Foams

    NASA Technical Reports Server (NTRS)

    Veretennikov, Igor; Glazier, James A.

    2004-01-01

    The main goal of this work is to better understand foam behavior both on the Earth and in microgravity conditions and to determine the relation between a foam's structure and wetness and its rheological properties. Our experiments focused on the effects of the bubble size distribution (BSD) on the foam behavior under gradual or stepwise in the liquid flow rate and on the onset of the convective instability. We were able to show experimentally, that the BSD affects foam rheology very strongly so any theory must take foam texture into account.

  6. Elastocapillary Instability in Mitochondrial Fission

    NASA Astrophysics Data System (ADS)

    Gonzalez-Rodriguez, David; Sart, Sébastien; Babataheri, Avin; Tareste, David; Barakat, Abdul I.; Clanet, Christophe; Husson, Julien

    2015-08-01

    Mitochondria are dynamic cell organelles that constantly undergo fission and fusion events. These dynamical processes, which tightly regulate mitochondrial morphology, are essential for cell physiology. Here we propose an elastocapillary mechanical instability as a mechanism for mitochondrial fission. We experimentally induce mitochondrial fission by rupturing the cell's plasma membrane. We present a stability analysis that successfully explains the observed fission wavelength and the role of mitochondrial morphology in the occurrence of fission events. Our results show that the laws of fluid mechanics can describe mitochondrial morphology and dynamics.

  7. Carpal instability of the wrist.

    PubMed

    Caggiano, Nicholas; Matullo, Kristofer S

    2014-01-01

    The scaphoid is stabilized by the scapholunate ligament (directly) and lunotriquetral ligament (indirectly). Disruption of either of these ligaments leads to a pattern of instability that, left untreated, leads to altered mechanics of the wrist and ultimately debilitating arthritis and collapse. Although arthroscopy remains the gold standard for diagnosis of these injuries, plain films and advanced imaging are useful adjuncts. In the acute setting, conservative treatment may be attempted, but recalcitrant cases require surgical stabilization. Salvage procedures are also available for those patients who fail initial stabilization or present with late degeneration. Copyright © 2014 Elsevier Inc. All rights reserved.

  8. Dynamic Instability of Barlike Modes

    NASA Astrophysics Data System (ADS)

    Durisen, Richard H.; Pickett, Brian K.; Bate, Matthew R.; Imamura, James N.; Brandl, Andreas; Sterzik, Michael F.

    Numerical simulations during the 1980's established that prompt binary formation (or ``fission'') through dynamic growth of barlike modes is aborted by gravitational torques. Because these instabilities may occur during star formation and because their outcome over long times is still uncertain, we have combined various linear analyses with simulations by hydrodynamics codes to refine our understanding. We show that it is in fact the torques which cause nonlinear saturation of the mode amplitude. Excellent agreement for the early nonlinear phase is obtained using radically different hydrodynamics codes. However, the ultimate outcome is sensitive to assumptions about dissipative heating and is also somewhat code-dependent.

  9. Imaging of postoperative shoulder instability.

    PubMed

    De Filippo, M; Pesce, A; Barile, A; Borgia, D; Zappia, M; Romano, A; Pogliacomi, F; Verdano, M; Pellegrini, A; Johnson, K

    2017-03-01

    Postoperative imaging in shoulder instability is still a challenge for radiologists due to various postsurgical anatomical findings that could be considered pathologic in treated shoulder. For this reason is very important a deep knowledge about surgical procedures, anatomical changes after surgery and the appropriate diagnostic imaging modalities to work up the symptomatic postoperative shoulder. Postoperative imaging options include use conventional radiography, magnetic resonance imaging (MRI), MRI arthrography, computed tomography (CT) and CT arthrography. The purpose of our review is to explain the different surgical procedures and to describe postoperative changes detected with radiological imaging.

  10. Theory on instability and transition

    NASA Technical Reports Server (NTRS)

    Smith, Frank T.

    1990-01-01

    The fundamental fluid dynamics governing instability and transition to turbulence in boundary layers are considered, and attention is focused on the key aspects of nonlinear dynamics central to the transition process and to turbulent boundary-layer phenomena. Emphasis is placed on truly nonlinear theories, in which the boundary layer mean-flow profile is completely altered from its original form. Nonlinear TS transitions, Euler-stage interactions, and vortex/wave interactions are discussed, and compressible boundary layers are analyzed. Connections with experiments and computations are outlined, along with overall trends including the extension of the nonlinear theory and the advancement in the compressible and other flow regimes.

  11. Shrinking instability of toroidal droplets.

    PubMed

    Fragkopoulos, Alexandros A; Pairam, Ekapop; Berger, Eric; Segre, Phil N; Fernández-Nieves, Alberto

    2017-03-14

    Toroidal droplets are inherently unstable due to surface tension. They can break up, similar to cylindrical jets, but also exhibit a shrinking instability, which is inherent to the toroidal shape. We investigate the evolution of shrinking toroidal droplets using particle image velocimetry. We obtain the flow field inside the droplets and show that as the torus evolves, its cross-section significantly deviates from circular. We then use the experimentally obtained velocities at the torus interface to theoretically reconstruct the internal flow field. Our calculation correctly describes the experimental results and elucidates the role of those modes that, among the many possible ones, are required to capture all of the relevant experimental features.

  12. Nonlinear Instability of Liquid Layers.

    NASA Astrophysics Data System (ADS)

    Newhouse, Lori Ann

    The nonlinear instability of two superposed viscous liquid layers in planar and axisymmetric configurations is investigated. In the planar configuration, the light layer fluid is bounded below by a wall and above by a heavy semiinfinite fluid. Gravity drives the instability. In the first axisymmetric configuration, the layer is confined between a cylindrical wall and a core of another fluid. In the second, a thread is suspended in an infinite fluid. Surface tension forces drive the instability in the axisymmetric configurations. The nonlinear evolution of the fluid-fluid interface is computed for layers of arbitrary thickness when their dynamics are fully coupled to those of the second fluid. Under the assumption of creeping flow, the flow field is represented by an interfacial distribution of Green's functions. A Fredholm integral equation of the second kind for the strength of the distribution is derived and then solved using an iterative technique. The Green's functions produce flow fields which are periodic in the direction parallel to the wall and have zero velocity on the wall. For small and moderate surface tension, planar layers evolve into a periodic array of viscous plumes which penetrate into the overlying fluid. The morphology of the plumes depends on the surface tension and the ratio of the fluid viscosities. As the viscosity of the layer increases, the plumes change from a well defined drop on top of a narrow stem to a compact column of rising fluid. The capillary instability of cylindrical interfaces and interfaces in which the core thickness varies in the axial direction are investigated. In both the unbounded and wall bounded configurations, the core evolves into a periodic array of elongated fluid drops connected by thin, almost cylindrical fluid links. The characteristics of the drop-link structure depend on the core thickness, the ratio of the core radius to the wall radius, and the ratio of the fluid viscosities. The factors controlling the

  13. Rotating Rayleigh-Taylor instability

    NASA Astrophysics Data System (ADS)

    Scase, M. M.; Baldwin, K. A.; Hill, R. J. A.

    2017-02-01

    The effect of rotation upon the classical Rayleigh-Taylor instability is investigated. We consider a two-layer system with an axis of rotation that is perpendicular to the interface between the layers. In general, we find that a wave mode's growth rate may be reduced by rotation. We further show that in some cases, unstable axisymmetric wave modes may be stabilized by rotating the system above a critical rotation rate associated with the mode's wavelength, the Atwood number, and the flow's aspect ratio.

  14. Spatiotemporal chaos involving wave instability

    NASA Astrophysics Data System (ADS)

    Berenstein, Igal; Carballido-Landeira, Jorge

    2017-01-01

    In this paper, we investigate pattern formation in a model of a reaction confined in a microemulsion, in a regime where both Turing and wave instability occur. In one-dimensional systems, the pattern corresponds to spatiotemporal intermittency where the behavior of the systems alternates in both time and space between stationary Turing patterns and traveling waves. In two-dimensional systems, the behavior initially may correspond to Turing patterns, which then turn into wave patterns. The resulting pattern also corresponds to a chaotic state, where the system alternates in both space and time between standing wave patterns and traveling waves, and the local dynamics may show vanishing amplitude of the variables.

  15. Transverse Instabilities in the Fermilab Recycler

    SciTech Connect

    Prost, L.R.; Burov, A.; Shemyakin, A.; Bhat, C.M.; Crisp, J.; Eddy, N.; /Fermilab

    2011-07-01

    Transverse instabilities of the antiproton beam have been observed in the Recycler ring soon after its commissioning. After installation of transverse dampers, the threshold for the instability limit increased significantly but the instability is still found to limit the brightness of the antiprotons extracted from the Recycler for Tevatron shots. In this paper, we describe observations of the instabilities during the extraction process as well as during dedicated studies. The measured instability threshold phase density agrees with the prediction of the rigid beam model within a factor of 2. Also, we conclude that the instability threshold can be significantly lowered for a bunch contained in a narrow and shallow potential well due to effective exclusion of the longitudinal tails from Landau damping.

  16. Mode-locking via dissipative Faraday instability.

    PubMed

    Tarasov, Nikita; Perego, Auro M; Churkin, Dmitry V; Staliunas, Kestutis; Turitsyn, Sergei K

    2016-08-09

    Emergence of coherent structures and patterns at the nonlinear stage of modulation instability of a uniform state is an inherent feature of many biological, physical and engineering systems. There are several well-studied classical modulation instabilities, such as Benjamin-Feir, Turing and Faraday instability, which play a critical role in the self-organization of energy and matter in non-equilibrium physical, chemical and biological systems. Here we experimentally demonstrate the dissipative Faraday instability induced by spatially periodic zig-zag modulation of a dissipative parameter of the system-spectrally dependent losses-achieving generation of temporal patterns and high-harmonic mode-locking in a fibre laser. We demonstrate features of this instability that distinguish it from both the Benjamin-Feir and the purely dispersive Faraday instability. Our results open the possibilities for new designs of mode-locked lasers and can be extended to other fields of physics and engineering.

  17. Late instability following total hip arthroplasty.

    PubMed

    Pulido, Luis; Restrepo, Camilo; Parvizi, Javad

    2007-06-01

    Instability is one of the most common complications after total hip arthroplasty and can present early or late after hip replacement. Late instability is considered if the event occurs five or more years after the primary arthroplasty, and in contrast to early dislocation, it appears to require operative intervention. The incidence of late instability may be greater than initially appreciated, and the cumulative rate rises with longer follow-up. The etiology of hip instability is often multifactorial with the presumed risk factors for late instability including long standing malposition of the components, trauma, deterioration in muscle mass, neurological status impairment and polyethylene wear. This article presents a synopsis of published studies on late instability and outlines our institutional experience with treatment of late dislocation following total hip arthroplasty occurring due to polyethylene wear.

  18. Mode-locking via dissipative Faraday instability

    PubMed Central

    Tarasov, Nikita; Perego, Auro M.; Churkin, Dmitry V.; Staliunas, Kestutis; Turitsyn, Sergei K.

    2016-01-01

    Emergence of coherent structures and patterns at the nonlinear stage of modulation instability of a uniform state is an inherent feature of many biological, physical and engineering systems. There are several well-studied classical modulation instabilities, such as Benjamin–Feir, Turing and Faraday instability, which play a critical role in the self-organization of energy and matter in non-equilibrium physical, chemical and biological systems. Here we experimentally demonstrate the dissipative Faraday instability induced by spatially periodic zig-zag modulation of a dissipative parameter of the system—spectrally dependent losses—achieving generation of temporal patterns and high-harmonic mode-locking in a fibre laser. We demonstrate features of this instability that distinguish it from both the Benjamin–Feir and the purely dispersive Faraday instability. Our results open the possibilities for new designs of mode-locked lasers and can be extended to other fields of physics and engineering. PMID:27503708

  19. Mode-locking via dissipative Faraday instability

    NASA Astrophysics Data System (ADS)

    Tarasov, Nikita; Perego, Auro M.; Churkin, Dmitry V.; Staliunas, Kestutis; Turitsyn, Sergei K.

    2016-08-01

    Emergence of coherent structures and patterns at the nonlinear stage of modulation instability of a uniform state is an inherent feature of many biological, physical and engineering systems. There are several well-studied classical modulation instabilities, such as Benjamin-Feir, Turing and Faraday instability, which play a critical role in the self-organization of energy and matter in non-equilibrium physical, chemical and biological systems. Here we experimentally demonstrate the dissipative Faraday instability induced by spatially periodic zig-zag modulation of a dissipative parameter of the system--spectrally dependent losses--achieving generation of temporal patterns and high-harmonic mode-locking in a fibre laser. We demonstrate features of this instability that distinguish it from both the Benjamin-Feir and the purely dispersive Faraday instability. Our results open the possibilities for new designs of mode-locked lasers and can be extended to other fields of physics and engineering.

  20. Infrequent microsatellite instability in oesophageal cancers.

    PubMed Central

    Muzeau, F.; Fléjou, J. F.; Belghiti, J.; Thomas, G.; Hamelin, R.

    1997-01-01

    Alterations of microsatellites have been found at relatively high frequency in hereditary and sporadic colorectal cancer and gastric and pancreatic cancers and at lower frequency in some other cancers. We determined the frequency of instability at 39 poly-CA microsatellite loci in 20 squamous cell carcinomas and 26 Barrett's adenocarcinomas of the oesophagus. None of the tumours presented instability for a high percentage of the tested loci. Four squamous cell carcinomas and six Barrett's adenocarcinomas showed microsatellite instability at one locus, and three Barrett's adenocarcinomas showed microsatellite instability at two loci. The presence of few loci showing microsatellite instability could be due to an instability background. We conclude that genetic defects in the DNA mismatch repair system do not play an important role in oesophageal cancers. Images Figure 1 PMID:9155055

  1. Absolute instability of the Gaussian wake profile

    NASA Technical Reports Server (NTRS)

    Hultgren, Lennart S.; Aggarwal, Arun K.

    1987-01-01

    Linear parallel-flow stability theory has been used to investigate the effect of viscosity on the local absolute instability of a family of wake profiles with a Gaussian velocity distribution. The type of local instability, i.e., convective or absolute, is determined by the location of a branch-point singularity with zero group velocity of the complex dispersion relation for the instability waves. The effects of viscosity were found to be weak for values of the wake Reynolds number, based on the center-line velocity defect and the wake half-width, larger than about 400. Absolute instability occurs only for sufficiently large values of the center-line wake defect. The critical value of this parameter increases with decreasing wake Reynolds number, thereby indicating a shrinking region of absolute instability with decreasing wake Reynolds number. If backflow is not allowed, absolute instability does not occur for wake Reynolds numbers smaller than about 38.

  2. Instability of time-periodic flows

    NASA Technical Reports Server (NTRS)

    Hall, P.

    1985-01-01

    The instabilities of some spatially and/or time-periodic flows are discussed, in particular, flows with curved streamlines which can support Taylor-Gortler vortices are described in detail. The simplest flow where this type of instability can occur is that due to the torsional oscillations of an infinitely long circular cylinder. For more complicated spatially varying time-periodic flows, a similar type of instability can occur and is spatially localized near the most unstable positions. When nonlinear effects are considered it is found that the instability modifies the steady streaming boundary layer induced by the oscillatory motion. It is shown that a rapidly rotating cylinder in a uniform flow is susceptible to a related type of instability; the appropriate stability equations are shown to be identical to those which govern the instability of a boussinesq fluid of Prandtl number unity heated time periodically from below.

  3. Anterior Eye Imaging with Optical Coherence Tomography

    NASA Astrophysics Data System (ADS)

    Huang, David; Li, Yan; Tang, Maolong

    The development of corneal and anterior segment optical coherence tomography (OCT) technology has advanced rapidly in recently years. The scan geometry and imaging wavelength are both important choices to make in designing anterior segment OCT systems. Rectangular scan geometry offers the least image distortion and is now used in most anterior OCT systems. The wavelength of OCT light source affects resolution and penetration. An optimal choice of the OCT imaging wavelength (840, 1,050, or 1,310 nm) depends on the application of interest. Newer generation Fourier-domain OCT technology can provide scan speed 100-1000 times faster than the time-domain technology. Various commercial anterior OCT systems are available on the market. A wide spectrum of diagnostic and surgical applications using anterior segment OCT had been investigated, including mapping of corneal and epithelial thicknesses, keratoconus screening, measuring corneal refractive power, corneal surgery planning and evaluation in LASIK, intracorneal ring implantation, assessment of angle closure glaucoma, anterior chamber biometry and intraocular lens implants, intraocular lens power calculation, and eye bank donor cornea screening.

  4. Anterior condylar displacement: its diagnosis and treatment.

    PubMed

    Weinberg, L A

    1975-08-01

    A deflective slide in centric relation to centric occlusion does not necessarily mean anterior condylar displacement. Its diagnosis and treatment depend on the correlation of three factors: the direction and magnitude of the mandibular slide from centric relation to centric occlusion, the change in vertical dimension of occlusion during the slide, and the position of the condyles in the fossae when the teeth are in the maximum occlusion (centric occlusion). When the change in vertical dimension almost equals to amount of slide from the deflective contact in centric relation to maximum intercuspation, very little anterior condylar displacement would be expected. Conversely, with proportionately little change in vertical dimension, more anterior condylar translation is required for a given degree of anterior slide. Examples of each type of anterior slide were related to the TMJ radiographs of the condylar position. If the direction and magnitude of the deflective occlusal contact can be correlated with the TMJ radiographs, the centric relation is "functional,'' and the clinically retruded mandibular position should be used. When this correlation does not exist, the centric relation is "dysfunctional'' and the terminal hinge position (retruded mandibular position) should not be used for restorative or corrective procedures. Examples of anterior condylar displacement were given, including deviation, with a comparison of "before'' and "after'' TMJ radiographs.

  5. Laser peripheral iridotomy changes anterior chamber architecture.

    PubMed

    Theinert, Christian; Wiedemann, Peter; Unterlauft, Jan D

    2017-01-19

    The pressure gradient between anterior and posterior chamber in acute angle closure (AAC) and primary angle closure suspects is balanced by a sufficient laser peripheral iridotomy (LPI). The anterior chamber changes induced by LPI in patients with unilateral AAC were examined and compared to healthy eyes to define threshold values, which may help to discriminate between healthy and diseased eyes. Using Scheimpflug photography, anterior chamber depth (ACD), anterior chamber volume (ACV), anterior chamber angle (ACA), and central corneal thickness (CCT) were measured before and after LPI in both eyes of unilateral AAC cases. These measurements were compared to a group of healthy control eyes to determine threshold values for ACD, ACV, and ACA. The ACD, ACV, and ACA increased significantly in the 25 AAC eyes after LPI. The ACD, ACV, ACA, and CCT values in the AAC eyes obtained before LPI were compared to a control group of 59 healthy eyes with wide open chamber angles. The cutoff values revealed by receiver operating characteristic analysis were 2.1 mm for ACD, 90.5 mm2 for ACV, and 27.25° for ACA. Our results confirm the significant changes of the anterior segments architecture induced by LPI in AAC eyes. The found threshold values for ACD, ACV, and ACA may help in daily clinical routine to discriminate between healthy eyes and those in need for a prophylactic LPI.

  6. Anterior Insula Volume and Guilt

    PubMed Central

    Belden, Andy C.; Barch, Deanna M.; Oakberg, Timothy J.; April, Laura M.; Harms, Michael P.; Botteron, Kelly N.; Luby, Joan L.

    2016-01-01

    IMPORTANCE This is the first study to date to examine volumetric alterations in the anterior insula (AI) as a potential biomarker for the course of childhood major depressive disorder (MDD). OBJECTIVES To examine whether children with a history of preschool-onset (PO) MDD show reduced AI volume, whether a specific symptom of PO MDD (pathological guilt) is related to AI volume reduction (given the known relationship between AI and guilt processing), and whether AI volumes predict subsequent likelihood of having an episode of MDD. DESIGN, SETTING, AND PARTICIPANTS In a prospective longitudinal study, 306 children (age range, 3.00–5.11 years) and caregivers completed DSM diagnostic assessments at 6 annual time points during 10 years as part of the Preschool Depression Study. Magnetic resonance imaging was completed on a subset of 145 school-age children (age range, 6.11–12.11 years). MAIN OUTCOMES AND MEASURES Whole-brain–adjusted AI volume measured using magnetic resonance imaging at school age and children’s diagnosis of MDD any time after their imaging. RESULTS Compared with children without a history of PO MDD, school-age children previously diagnosed as having PO MDD had smaller left and right AI volumes (Wilks Λ = 0.94, F2,124 = 3.37, P = .04, Cohen d = 0.23). However, the effect of PO MDD on reduced AI volumes was better explained by children’s experience of pathological guilt during preschool (Λ = 0.91, F2,120 = 6.17, P = .003, d = .30). When covarying for children’s lifetime history of MDD episodes, their experience of pathological guilt during preschool, as well as their sex and age at the time of imaging, schoolchildren’s right-side AI volume was a significant predictor of being diagnosed as having an MDD episode after imaging (odds ratio, 0.96; 95% CI, 0.01–0.75; P = .03). CONCLUSIONS AND RELEVANCE These results provide evidence that structural abnormalities in AI volume are related to the neurobiology of depressive disorders starting in

  7. Patient expectations of primary and revision anterior cruciate ligament reconstruction.

    PubMed

    Feucht, Matthias J; Cotic, Matthias; Saier, Tim; Minzlaff, Philipp; Plath, Johannes E; Imhoff, Andreas B; Hinterwimmer, Stefan

    2016-01-01

    Unrealistic patient expectations have been shown to negatively influence patient-reported outcomes in orthopaedic surgery. Knowledge about patient expectations is important to associate preoperative expectations with the reasonable outcome of a specific procedure. The purpose of this study was to prospectively analyse and to compare patient expectations of primary and revision anterior cruciate ligament reconstruction (ACLR) and to assess the factors associated with patient expectations. Preoperative expectations of 181 consecutive patients undergoing ACLR were assessed prospectively using a 5-item questionnaire. Primary ACLR (P-ACLR) was performed in 133 patients (73%), whereas 48 patients (27%) underwent revision ACLR (R-ACLR). The questionnaire assessed the expectation of the overall condition of the knee joint, return to sports, instability, pain, and risk of osteoarthritis. All patients expected a normal (38%) or nearly normal (62%) condition of the knee joint. Return to sports at the same level was expected by 91%. With regard to instability (pain), no instability (pain) independent of the activity level was expected by 77% (58%). No or only a slightly increased risk of the development of osteoarthritis was expected by 98%. The R-ACLR group showed a significantly lower expectation of the overall condition (p = 0.001), return to sports (p < 0.001), and pain (p = 0.002). No statistically significant difference was found between female and male patients (n.s.). In the P-ACLR group, patients with a history of previous knee surgery showed inferior expectations of return to sports (p = 0.015) and risk of osteoarthritis (p = 0.011). Age, number of previous knee surgeries, and pre-injury sports level significantly influenced patient expectations. Overall, patient expectations of ACL reconstruction are high. Patients undergoing revision ACL reconstruction have lower but still demanding expectations. Younger patients, patients without a history of knee surgery, and

  8. Modulational instabilities in relativistic pair plasmas

    SciTech Connect

    Mendonça, J. T.

    2016-05-15

    We study the modulational instability of an intense photon beam in a relativistic pair plasma. We use the wave-kinetic description of the photon field and relativistic fluid equations for electrons and positrons. This allows us to consider the influence of the photon spectral distribution and photon recoil effects on the instability threshold and growth rates. The case of very low frequencies modulations, well below plasma frequency, is compared to that of high-frequency modulations corresponding to the plasmon decay instability.

  9. Laser driven instabilities in inertial confinement fusion

    SciTech Connect

    Kruer, W.L.

    1990-06-04

    Parametric instabilities excited by an intense electromagnetic wave in a plasma is a fundamental topic relevant to many applications. These applications include laser fusion, heating of magnetically-confined plasmas, ionospheric modification, and even particle acceleration for high energy physics. In laser fusion, these instabilities have proven to play an essential role in the choice of laser wavelength. Characterization and control of the instabilities is an ongoing priority in laser plasma experiments. Recent progress and some important trends will be discussed. 8 figs.

  10. Filamentation instability in a quantum magnetized plasma

    SciTech Connect

    Bret, A.

    2008-02-15

    The filamentation instability occurring when a nonrelativistic electron beam passes through a quantum magnetized plasma is investigated by means of a cold quantum magnetohydrodynamic model. It is proved that the instability can be completely suppressed by quantum effects if and only if a finite magnetic field is present. A dimensionless parameter is identified that measures the strength of quantum effects. Strong quantum effects allow for a much smaller magnetic field to suppress the instability than in the classical regime.

  11. Radiological and functional outcome after anterior lumbar interbody spinal fusion.

    PubMed

    Christensen, F B; Karlsmose, B; Hansen, E S; Bünger, C E

    1996-01-01

    Outcome after anterior spinal fusion has mainly been studied radiologically and reported fusion rates vary greatly. The aim of this study was to investigate radiological and long-term clinical outcome. The study comprised 120 consecutive patients, operated on during the period 1979-1987, with single-or two-level anterior interbody spinal fusion due to disc degeneration or isthmic spondylolisthesis with lumbar instability. In 64 patients a supplemental facet joint fusion was performed. Clinical outcome was evaluated 5-13 years after surgery using the patient-administered Dallas Pain Questionnaire (DPQ). Radiological outcome was determined on the basis of radiographs taken at a 2-year follow-up assessed by independent observers. The radiological follow-up rate was 98%. Complete fusion was found in 52%, questionable fusion in 24%, and definitive pseudoarthrosis in 24% of patients. Radiological results were poor in patients who had undergone previous spinal surgery (P < 0.05) and in those with two-level fusion (P < 0.05). The DPQ reply rate was 80%. Sixty-six patients claimed improvement in all functional groups. Patients with complete or questionable union had significantly better results than did those with non-union (P < 0.01). Poorer functional outcome was found in patients who had undergone previous spinal surgery (P < 0.01) or fusion at the L4/L5 level (P < 0.05), in those who had responded poorly to the preoperative test brace (P < 0.05), and in those above 45 years old at the time of surgery (P < 0.05). Radiological and functional outcome did not vary according to whether patients were treated postoperatively with a plaster jacket or with facet screw fixation. The study demonstrated a functional success rate of approximately 66% following anterior lumbar spinal fusion after a mean follow-up of 8 years. There was a clear tendency for poorer prognosis for patients who had undergone previous spinal surgery, those aged above 45 years, those operated at the L4/L5

  12. Two-Beam Instability in Electron Cooling

    SciTech Connect

    Burov, Alexey V.; /Fermilab

    2006-04-01

    The drift motion of cooling electrons makes them able to respond to transverse perturbations of a cooled ion beam. This response may lead to dipole or quadrupole transverse instabilities at specific longitudinal wave numbers. While the dipole instabilities can be suppressed by a combination of the Landau damping, machine impedance, and the active damper, the quadrupole and higher order modes can lead to either emittance growth, or a lifetime degradation, or both. The growth rates of these instabilities are strongly determined by the machine x-y coupling. Thus, tuning out of the coupling resonance and/or reduction of the machine coupling can be an efficient remedy for these instabilities.

  13. Measuring Frequency Instability Of A Large Antenna

    NASA Technical Reports Server (NTRS)

    Otoshi, Tom Y.; Lutes, George F.; Franco, Manuel M.

    1994-01-01

    Frequency instability of antenna under test determined from measurement of phase deviation between outputs of two antennas. Fiber-optic system used to minimize spurious component of frequency instability contributed by propagation of signal from reference antenna to Allan-variance-measuring instrument. Intended primarily to reveal contributions of wind and air-temperature effects on antenna and beam-waveguide structures to overall frequency instabilities of received signals. Technique simpler, less expensive, potentially capable of providing instability data in shorter measuring times, and more precise.

  14. Marangoni instability in a liquid sheet

    NASA Technical Reports Server (NTRS)

    Oron, A.; Deissler, R. J.; Duh, J. C.

    1995-01-01

    We study the onset of a pure Marangoni convection in a liquid layer with two deformable interfaces in the no-gravity environment. Both oscillatory and stationary instabilities are considered for a wide range of parameters. It is shown that only stationary instability is possible when surface tension at the colder interface is lower than that at the hotter one. Oscillatory instability tends to disappear and to be replaced by the stationary instability with increase of the Prandtl number and decrease of surface tension at the colder interface.

  15. Two-Fluid Interface Instability Being Studied

    NASA Technical Reports Server (NTRS)

    Niederhaus, Charles E.

    2003-01-01

    The interface between two fluids of different density can experience instability when gravity acts normal to the surface. The relatively well known Rayleigh-Taylor (RT) instability results when the gravity is constant with a heavy fluid over a light fluid. An impulsive acceleration applied to the fluids results in the Richtmyer-Meshkov (RM) instability. The RM instability occurs regardless of the relative orientation of the heavy and light fluids. In many systems, the passing of a shock wave through the interface provides the impulsive acceleration. Both the RT and RM instabilities result in mixing at the interface. These instabilities arise in a diverse array of circumstances, including supernovas, oceans, supersonic combustion, and inertial confinement fusion (ICF). The area with the greatest current interest in RT and RM instabilities is ICF, which is an attempt to produce fusion energy for nuclear reactors from BB-sized pellets of deuterium and tritium. In the ICF experiments conducted so far, RM and RT instabilities have prevented the generation of net-positive energy. The $4 billion National Ignition Facility at Lawrence Livermore National Laboratory is being constructed to study these instabilities and to attempt to achieve net-positive yield in an ICF experiment.

  16. Internet worms and global routing instabilities

    NASA Astrophysics Data System (ADS)

    Cowie, James; Ogielski, Andy T.; Premore, B. J.; Yuan, Yougu

    2002-07-01

    We analyze the global BGP routing instabilities observed during the Code Red II and Nimda worm attacks in July and September 2001, respectively. Compelling analysis is shown on the correlation between the observed instabilities and the worm attacks. We analyze router failure modes that can be triggered by the abnormal traffic during the worm attack and how they can lead to global routing instability. Independent research has partially confirmed that such failure modes can and likely do occur in practice. Highly detailed large-scale simulations help close the loop, indicating that such failure modes do in fact trigger the kind of widespread BGP instabilities that were observed empirically.

  17. [Cervical spine instability in the surgical patient].

    PubMed

    Barbeito, A; Guerri-Guttenberg, R A

    2014-03-01

    Many congenital and acquired diseases, including trauma, may result in cervical spine instability. Given that airway management is closely related to the movement of the cervical spine, it is important that the anesthesiologist has detailed knowledge of the anatomy, the mechanisms of cervical spine instability, and of the effects that the different airway maneuvers have on the cervical spine. We first review the normal anatomy and biomechanics of the cervical spine in the context of airway management and the concept of cervical spine instability. In the second part, we review the protocols for the management of cervical spine instability in trauma victims and some of the airway management options for these patients.

  18. The Chemistry of Beer Instability

    NASA Astrophysics Data System (ADS)

    Stewart, Graham G.

    2004-07-01

    Compared to most other alcoholic beverages, beer is unique because it is unstable when in the final package. This instability can be divided into biological and nonbiological instability. Nonbiological stability of beer involves a wide range of chemical processes and can be considered in a number of categories: physical, flavor, light, foam, and gushing. It is the balance between flavanoid polyphenols (tannoids) and sensitive proteins that specifically combine with polyphenols to form haze that largely dictates physical stability. The flavor stability of beer primarily depends on the oxygen concentration of packaged beer but is influenced by all stages of the brewing process. Foam stability in a glass of beer reflects the quality of the beverage. The backbone of foam is hydrophobic polypeptides. Novel brewing processes such as high-gravity brewing result in a disproportionate loss of these polypeptides and have a negative effect on the foam stability of the resulting beer. Beer is light sensitive, especially in the 350 500 nm range. Beer exposed to this wavelength range in clear or green glass containers quickly develop nauseous skunky-like off-flavors resulting from the formation of 3-methyl-2-butene-1-thiol. Methods of enhancing all of these types of beer stability are discussed.

  19. Radiation-induced genomic instability

    NASA Technical Reports Server (NTRS)

    Kronenberg, A.

    1994-01-01

    Quantitative assessment of the heritable somatic effects of ionizing radiation exposures has relied upon the assumption that radiation-induced lesions were 'fixed' in the DNA prior to the first postirradiation mitosis. Lesion conversion was thought to occur during the initial round of DNA replication or as a consequence of error-prone enzymatic processing of lesions. The standard experimental protocols for the assessment of a variety of radiation-induced endpoints (cell death, specific locus mutations, neoplastic transformation and chromosome aberrations) evaluate these various endpoints at a single snapshot in time. In contrast with the aforementioned approaches, some studies have specifically assessed radiation effects as a function of time following exposure. Evidence has accumulated in support of the hypothesis that radiation exposure induces a persistent destabilization of the genome. This instability has been observed as a delayed expression of lethal mutations, as an enhanced rate of accumulation of non-lethal heritable alterations, and as a progressive intraclonal chromosomal heterogeneity. The genetic controls and biochemical mechanisms underlying radiation-induced genomic instability have not yet been delineated. The aim is to integrate the accumulated evidence that suggests that radiation exposure has a persistent effect on the stability of the mammalian genome.

  20. Rogue Waves and Modulational Instability

    NASA Astrophysics Data System (ADS)

    Zakharov, V. E.; Dyachenko, A.

    2015-12-01

    The most plausible cause of rogue wave formation in a deep ocean is development of modulational instability of quasimonochromatic wave trains. An adequate model for study of this phenomenon is the Euler equation for potential flow of incompressible fluid with free surface in 2-D geometry. Numerical integration of these equations confirms completely the conjecture of rogue wave formation from modulational instability but the procedure is time consuming for determination of rogue wave appearance probability for a given shape of wave energy spectrum. This program can be realized in framework of simpler model using replacement of the exact interaction Hamiltonian by more compact Hamiltonian. There is a family of such models. The popular one is the Nonlinear Schrodinger equation (NLSE). This model is completely integrable and suitable for numerical simulation but we consider that it is oversimplified. It misses such important phenomenon as wave breaking. Recently, we elaborated much more reliable model that describes wave breaking but is as suitable as NLSE from the point of numerical modeling. This model allows to perform massive numerical experiments and study statistics of rogue wave formation in details.

  1. Option price and market instability

    NASA Astrophysics Data System (ADS)

    Baaquie, Belal E.; Yu, Miao

    2017-04-01

    An option pricing formula, for which the price of an option depends on both the value of the underlying security as well as the velocity of the security, has been proposed in Baaquie and Yang (2014). The FX (foreign exchange) options price was empirically studied in Baaquie et al., (2014), and it was found that the model in general provides an excellent fit for all strike prices with a fixed model parameters-unlike the Black-Scholes option price Hull and White (1987) that requires the empirically determined implied volatility surface to fit the option data. The option price proposed in Baaquie and Cao Yang (2014) did not fit the data during the crisis of 2007-2008. We make a hypothesis that the failure of the option price to fit data is an indication of the market's large deviation from its near equilibrium behavior due to the market's instability. Furthermore, our indicator of market's instability is shown to be more accurate than the option's observed volatility. The market prices of the FX option for various currencies are studied in the light of our hypothesis.

  2. Radiation-induced genomic instability

    NASA Technical Reports Server (NTRS)

    Kronenberg, A.

    1994-01-01

    Quantitative assessment of the heritable somatic effects of ionizing radiation exposures has relied upon the assumption that radiation-induced lesions were 'fixed' in the DNA prior to the first postirradiation mitosis. Lesion conversion was thought to occur during the initial round of DNA replication or as a consequence of error-prone enzymatic processing of lesions. The standard experimental protocols for the assessment of a variety of radiation-induced endpoints (cell death, specific locus mutations, neoplastic transformation and chromosome aberrations) evaluate these various endpoints at a single snapshot in time. In contrast with the aforementioned approaches, some studies have specifically assessed radiation effects as a function of time following exposure. Evidence has accumulated in support of the hypothesis that radiation exposure induces a persistent destabilization of the genome. This instability has been observed as a delayed expression of lethal mutations, as an enhanced rate of accumulation of non-lethal heritable alterations, and as a progressive intraclonal chromosomal heterogeneity. The genetic controls and biochemical mechanisms underlying radiation-induced genomic instability have not yet been delineated. The aim is to integrate the accumulated evidence that suggests that radiation exposure has a persistent effect on the stability of the mammalian genome.

  3. Combustion instability modeling and analysis

    SciTech Connect

    Santoro, R.J.; Yang, V.; Santavicca, D.A.

    1995-10-01

    It is well known that the two key elements for achieving low emissions and high performance in a gas turbine combustor are to simultaneously establish (1) a lean combustion zone for maintaining low NO{sub x} emissions and (2) rapid mixing for good ignition and flame stability. However, these requirements, when coupled with the short combustor lengths used to limit the residence time for NO formation typical of advanced gas turbine combustors, can lead to problems regarding unburned hydrocarbons (UHC) and carbon monoxide (CO) emissions, as well as the occurrence of combustion instabilities. Clearly, the key to successful gas turbine development is based on understanding the effects of geometry and operating conditions on combustion instability, emissions (including UHC, CO and NO{sub x}) and performance. The concurrent development of suitable analytical and numerical models that are validated with experimental studies is important for achieving this objective. A major benefit of the present research will be to provide for the first time an experimentally verified model of emissions and performance of gas turbine combustors.

  4. Adhesional instabilities and gecko locomotion

    NASA Astrophysics Data System (ADS)

    Williams, John A.

    2015-01-01

    Geckos possess a remarkable ability to run rapidly on both walls and ceilings and in recent years the mechanisms that underlie this facility have come under close scrutiny. It is now generally agreed that one of the principal mechanisms of adhesion relies on the action of van der Waal forces acting between the final extremely fine structure of the gecko toe and the underlying substrate. High speed video analysis shows that adhesive contact is both made and broken in intervals of less than 20 ms and this suggests that the mechanism of detachment is one of adhesive instability rather than steady-state peeling. By considering the gecko seta/spatula as a Euler-Bernoulli cantilever it is possible to model this instability in non-dimensional terms and thus to test the analysis at a much larger scale with more conventional engineering materials. When applied to the scale and material combination appropriate to a gecko spatula, the predicted critical load, of around 10 nN, is close to values that have been observed using and AFM cantilever and a single detached spatula.

  5. Active control of combustion instability

    SciTech Connect

    Lang, W.; Poinsot, T.; Candel, S.

    1987-12-01

    The principle of 'antisound' is used to construct a method for the suppression of combustion instabilities. This active instability control (AIC) method uses external acoustic excitation by a loudspeaker to suppress the oscillations of a flame. The excitation signal is provided by a microphone located upstream of the flame. This signal is filtered, processed, amplified, and sent to the loudspeaker. The AIC method is validated on a laboratory combustor. It allows the suppression of all unstable modes of the burner for any operating ratio. The influence of the microphone and loudspeaker locations on the performance of the AIC system is described. For a given configuration, domains of stability, i.e., domains where the AIC system parameters provide suppression of the oscillation, are investigated. Measurements of the electric input of the loudspeaker show that the energy consumption of the AIC system is almost negligible and suggest that this method could be used for industrial combustor stabilization. Finally, a simple model describing the effects of the AIC system is developed and its results compared to the experiment.

  6. Electric Field Induced Interfacial Instabilities

    NASA Technical Reports Server (NTRS)

    Kusner, Robert E.; Min, Kyung Yang; Wu, Xiao-Lun; Onuki, Akira

    1996-01-01

    The study of the interface in a charge-free, nonpolar, critical and near-critical binary fluid in the presence of an externally applied electric field is presented. At sufficiently large fields, the interface between the two phases of the binary fluid should become unstable and exhibit an undulation with a predefined wavelength on the order of the capillary length. As the critical point is approached, this wavelength is reduced, potentially approaching length-scales such as the correlation length or critical nucleation radius. At this point the critical properties of the system may be affected. In zero gravity, the interface is unstable at all long wavelengths in the presence of a field applied across it. It is conjectured that this will cause the binary fluid to break up into domains small enough to be outside the instability condition. The resulting pattern formation, and the effects on the critical properties as the domains approach the correlation length are of acute interest. With direct observation, laser light scattering, and interferometry, the phenomena can be probed to gain further understanding of interfacial instabilities and the pattern formation which results, and dimensional crossover in critical systems as the critical fluctuations in a particular direction are suppressed by external forces.

  7. Genome instability in Alzheimer disease.

    PubMed

    Hou, Yujun; Song, Hyundong; Croteau, Deborah L; Akbari, Mansour; Bohr, Vilhelm A

    2017-01-01

    Alzheimer's disease (AD) is a progressive neurodegenerative disorder and the most common form of dementia. Autosomal dominant, familial AD (fAD) is very rare and caused by mutations in amyloid precursor protein (APP), presenilin-1 (PSEN-1), and presenilin-2 (PSEN-2) genes. The pathogenesis of sporadic AD (sAD) is more complex and variants of several genes are associated with an increased lifetime risk of AD. Nuclear and mitochondrial DNA integrity is pivotal during neuronal development, maintenance and function. DNA damage and alterations in cellular DNA repair capacity have been implicated in the aging process and in age-associated neurodegenerative diseases, including AD. These findings are supported by research using animal models of AD and in DNA repair deficient animal models. In recent years, novel mechanisms linking DNA damage to neuronal dysfunction have been identified and have led to the development of noninvasive treatment strategies. Further investigations into the molecular mechanisms connecting DNA damage to AD pathology may help to develop novel treatment strategies for this debilitating disease. Here we provide an overview of the role of genome instability and DNA repair deficiency in AD pathology and discuss research strategies that include genome instability as a component. Published by Elsevier B.V.

  8. Genome instability, cancer and aging

    PubMed Central

    Maslov, Alexander Y.; Vijg, Jan

    2015-01-01

    DNA damage-driven genome instability underlies the diversity of life forms generated by the evolutionary process but is detrimental to the somatic cells of individual organisms. The cellular response to DNA damage can be roughly divided in two parts. First, when damage is severe, programmed cell death may occur or, alternatively, temporary or permanent cell cycle arrest. This protects against cancer but can have negative effects on the long term, e.g., by depleting stem cell reservoirs. Second, damage can be repaired through one or more of the many sophisticated genome maintenance pathways. However, erroneous DNA repair and incomplete restoration of chromatin after damage is resolved, produce mutations and epimutations, respectively, both of which have been shown to accumulate with age. An increased burden of mutations and/or epimutations in aged tissues increases cancer risk and adversely affects gene transcriptional regulation, leading to progressive decline in organ function. Cellular degeneration and uncontrolled cell proliferation are both major hallmarks of aging. Despite the fact that one seems to exclude the other, they both may be driven by a common mechanism. Here, we review age related changes in the mammalian genome and their possible functional consequences, with special emphasis on genome instability in stem/progenitor cells. PMID:19344750

  9. Subsidence and nonunion after anterior cervical interbody fusion using a stand-alone polyetheretherketone (PEEK) cage.

    PubMed

    Yang, Jae Jun; Yu, Chang Hun; Chang, Bong-Soon; Yeom, Jin Sup; Lee, Jae Hyup; Lee, Choon-Ki

    2011-03-01

    The purposes of the present study are to evaluate the subsidence and nonunion that occurred after anterior cervical discectomy and fusion using a stand-alone intervertebral cage and to analyze the risk factors for the complications. Thirty-eight patients (47 segments) who underwent anterior cervical fusion using a stand-alone polyetheretherketone (PEEK) cage and an autologous cancellous iliac bone graft from June 2003 to August 2008 were enrolled in this study. The anterior and posterior segmental heights and the distance from the anterior edge of the upper vertebra to the anterior margin of the cage were measured on the plain radiographs. Subsidence was defined as ≥ a 2 mm (minor) or 3 mm (major) decrease of the segmental height at the final follow-up compared to that measured at the immediate postoperative period. Nonunion was evaluated according to the instability being ≥ 2 mm in the interspinous distance on the flexion-extension lateral radiographs. The anterior and posterior segmental heights decreased from the immediate postoperative period to the final follow-up at 1.33 ± 1.46 mm and 0.81 ± 1.27 mm, respectively. Subsidence ≥ 2 mm and 3 mm were observed in 12 segments (25.5%) and 7 segments (14.9%), respectively. Among the expected risk factors for subsidence, a smaller anteroposterior (AP) diameter (14 mm vs. 12 mm) of cages (p = 0.034; odds ratio [OR], 0.017) and larger intraoperative distraction (p = 0.041; OR, 3.988) had a significantly higher risk of subsidence. Intervertebral nonunion was observed in 7 segments (7/47, 14.9%). Compared with the union group, the nonunion group had a significantly higher ratio of two-level fusion to one-level fusions (p = 0.001). Anterior cervical fusion using a stand-alone cage with a large AP diameter while preventing anterior intraoperative over-distraction will be helpful to prevent the subsidence of cages. Two-level cervical fusion might require more careful attention for avoiding nonunion.

  10. Subsidence and Nonunion after Anterior Cervical Interbody Fusion Using a Stand-Alone Polyetheretherketone (PEEK) Cage

    PubMed Central

    Yang, Jae Jun; Yu, Chang Hun; Yeom, Jin Sup; Lee, Jae Hyup; Lee, Choon-Ki

    2011-01-01

    Background The purposes of the present study are to evaluate the subsidence and nonunion that occurred after anterior cervical discectomy and fusion using a stand-alone intervertebral cage and to analyze the risk factors for the complications. Methods Thirty-eight patients (47 segments) who underwent anterior cervical fusion using a stand-alone polyetheretherketone (PEEK) cage and an autologous cancellous iliac bone graft from June 2003 to August 2008 were enrolled in this study. The anterior and posterior segmental heights and the distance from the anterior edge of the upper vertebra to the anterior margin of the cage were measured on the plain radiographs. Subsidence was defined as ≥ a 2 mm (minor) or 3 mm (major) decrease of the segmental height at the final follow-up compared to that measured at the immediate postoperative period. Nonunion was evaluated according to the instability being ≥ 2 mm in the interspinous distance on the flexion-extension lateral radiographs. Results The anterior and posterior segmental heights decreased from the immediate postoperative period to the final follow-up at 1.33 ± 1.46 mm and 0.81 ± 1.27 mm, respectively. Subsidence ≥ 2 mm and 3 mm were observed in 12 segments (25.5%) and 7 segments (14.9%), respectively. Among the expected risk factors for subsidence, a smaller anteroposterior (AP) diameter (14 mm vs. 12 mm) of cages (p = 0.034; odds ratio [OR], 0.017) and larger intraoperative distraction (p = 0.041; OR, 3.988) had a significantly higher risk of subsidence. Intervertebral nonunion was observed in 7 segments (7/47, 14.9%). Compared with the union group, the nonunion group had a significantly higher ratio of two-level fusion to one-level fusions (p = 0.001). Conclusions Anterior cervical fusion using a stand-alone cage with a large AP diameter while preventing anterior intraoperative over-distraction will be helpful to prevent the subsidence of cages. Two-level cervical fusion might require more careful attention

  11. Lumbar facet cyst resolution following anterior interbody fusion.

    PubMed

    Massey, Gene M; Caputo, Adam M; Michael, Keith W; Isaacs, Robert E; Brown, Christopher R

    2013-12-01

    Facet cysts are a relatively common source of neural compression in the lumbar spine. Open decompression and fusion are frequently used to treat the stenosis and instability associated with this pathology. Recently, anterior lumbar interbody fusion (ALIF) has increased in popularity for the treatment of lumbar degenerative conditions. ALIF may achieve indirect decompression of the neural elements with less surgical morbidity than conventional open approaches. To date, there are no published reports describing the use of indirect decompression or interbody fusion for the treatment of facet cysts. We report a patient who developed an L4-L5 facet cyst secondary to degenerative changes and spondylolisthesis. ALIF with posterior instrumentation was used to address his condition. Six months after surgery, the patient had complete resolution of his symptoms. MRI revealed complete resolution of the facet cyst. This patient provides previously unreported evidence that interbody fusion alone may result in facet cyst resolution. Clinical studies are needed to evaluate if interbody fusion can consistently relieve the symptoms associated with facet cysts without the use of direct decompression.

  12. Evaluation and comparison of clinical results of femoral fixation devices in arthroscopic anterior cruciate ligament reconstruction.

    PubMed

    Aydin, Deniz; Ozcan, Mert

    2016-03-01

    Several femoral fixation devices are available for hamstring tendon autograft in anterior cruciate ligament (ACL) reconstruction, but the best technique is debatable. We hypothesised that different suspensory femoral fixation techniques have no superiority over each other. The aim of this study was to evaluate and compare the clinical results of different suspensory femoral fixation devices in arthroscopic ACL reconstruction. This was a Level III, retrospective, comparative study. A total of 100 consecutive patients who underwent arthroscopic ACL reconstruction in a single institution with a mean follow-up time of 40 months (12-67 months) were divided into three groups according to femoral fixation devices as 'Endobutton' (n=34), 'Transfix' (n=35) and 'Aperfix' (n=31). The length of painful period after surgery, time to return to work and sporting activities, final range of motion, anterior drawer and Lachman tests, knee instability symptoms, International Knee Documentation Committee (IKDC) subjective knee evaluation score, Short Form 36 (SF-36) score, Lysholm knee score and Tegner point of the patients were evaluated and compared between groups. There were no significant differences between the groups. All techniques led to significant recovery in knee instability tests and symptoms. In this study, the clinical results of different suspensory femoral fixation techniques were found to be similar. We believe that different femoral fixation techniques have no effect on clinical results provided that the technique is correctly applied. The surgeon must choose a technique appropriate to his or her experience. Copyright © 2015 Elsevier B.V. All rights reserved.

  13. Anterior tibia spine fracture in children: follow-up evaluation by biomechanical studies.

    PubMed

    Lee, Y H; Chin, L S; Wang, N H; Hou, C H; Lo, W H

    1996-09-01

    The treatment of anterior tibial spine (ATS) fracture in children is in controversy. Previous studies have shown that most of the children who sustained ATS fractures have objective evidence of the anterior cruciate ligament (ACL) laxity at follow-up, but detailed biomechanical analysis of the knee joint has seldom been performed. Eight ATS fractures in children at a mean age of 12 years were treated from 1989 to 1994. Two were of Meyer's classification type I, 3 were of type II, and 3 were of type III. The treatment varied from casting to open reduction & internal fixation (ORIF) by pulling through suture or biofix absorbable screw. Patients were followed with radiological, clinical and biomechanical analysis. KT 1000 knee arthrometer was used to evaluate the laxity of ACL. Cybex isokinetic machine was used to evaluate knee extensor and flexor strength. During an average follow-up period of 47 months, all fractures showed to unite well on X-ray except 1 untreated type I fracture who had malunion. Only one had subjective complaint of instability, but 3 had clinical signs of instability. Objective evidence of laxity, determined by KT-1000 arthrometer, was noted in 4 patients. Decreased muscle strength, determined by Cybex isokinetic machine, was more prominent in hamstrings than in quadriceps. Patients with milder ATS fracture (type I & II), if treated inappropriately, may still result in ACL laxity and knee muscle strength deficiency. Type III ATS fractures, if treated well by ORIF, tend to recover nearly normal ACL function and muscle strength.

  14. Simultaneous Excitation and Analysis of Three Instabilities in Magnetized Plasma

    SciTech Connect

    Dimitriu, D. G.; Ionita, C.; Schrittwieser, R. W.

    2008-03-19

    Experimental results are presented on the simultaneous excitation of three low-frequency instabilities in the magnetized plasma column of a Q-machine, namely the potential relaxation instability, the electrostatic ion-cyclotron instability and the Kelvin-Helmholtz instability. The influence of the magnetic field intensity on the appearance of these instabilities was investigated.

  15. Testing the gravitational instability hypothesis?

    NASA Technical Reports Server (NTRS)

    Babul, Arif; Weinberg, David H.; Dekel, Avishai; Ostriker, Jeremiah P.

    1994-01-01

    We challenge a widely accepted assumption of observational cosmology: that successful reconstruction of observed galaxy density fields from measured galaxy velocity fields (or vice versa), using the methods of gravitational instability theory, implies that the observed large-scale structures and large-scale flows were produced by the action of gravity. This assumption is false, in that there exist nongravitational theories that pass the reconstruction tests and gravitational theories with certain forms of biased galaxy formation that fail them. Gravitational instability theory predicts specific correlations between large-scale velocity and mass density fields, but the same correlations arise in any model where (a) structures in the galaxy distribution grow from homogeneous initial conditions in a way that satisfies the continuity equation, and (b) the present-day velocity field is irrotational and proportional to the time-averaged velocity field. We demonstrate these assertions using analytical arguments and N-body simulations. If large-scale structure is formed by gravitational instability, then the ratio of the galaxy density contrast to the divergence of the velocity field yields an estimate of the density parameter Omega (or, more generally, an estimate of beta identically equal to Omega(exp 0.6)/b, where b is an assumed constant of proportionality between galaxy and mass density fluctuations. In nongravitational scenarios, the values of Omega or beta estimated in this way may fail to represent the true cosmological values. However, even if nongravitational forces initiate and shape the growth of structure, gravitationally induced accelerations can dominate the velocity field at late times, long after the action of any nongravitational impulses. The estimated beta approaches the true value in such cases, and in our numerical simulations the estimated beta values are reasonably accurate for both gravitational and nongravitational models. Reconstruction tests

  16. Interfacial instabilities in vibrated fluids

    NASA Astrophysics Data System (ADS)

    Porter, Jeff; Laverón-Simavilla, Ana; Tinao Perez-Miravete, Ignacio; Fernandez Fraile, Jose Javier

    2016-07-01

    Vibrations induce a range of different interfacial phenomena in fluid systems depending on the frequency and orientation of the forcing. With gravity, (large) interfaces are approximately flat and there is a qualitative difference between vertical and horizontal forcing. Sufficient vertical forcing produces subharmonic standing waves (Faraday waves) that extend over the whole interface. Horizontal forcing can excite both localized and extended interfacial phenomena. The vibrating solid boundaries act as wavemakers to excite traveling waves (or sloshing modes at low frequencies) but they also drive evanescent bulk modes whose oscillatory pressure gradient can parametrically excite subharmonic surface waves like cross-waves. Depending on the magnitude of the damping and the aspect ratio of the container, these locally generated surfaces waves may interact in the interior resulting in temporal modulation and other complex dynamics. In the case where the interface separates two fluids of different density in, for example, a rectangular container, the mass transfer due to vertical motion near the endwalls requires a counterflow in the interior region that can lead to a Kelvin-Helmholtz type instability and a ``frozen wave" pattern. In microgravity, the dominance of surface forces favors non-flat equilibrium configurations and the distinction between vertical and horizontal applied forcing can be lost. Hysteresis and multiplicity of solutions are more common, especially in non-wetting systems where disconnected (partial) volumes of fluid can be established. Furthermore, the vibrational field contributes a dynamic pressure term that competes with surface tension to select the (time averaged) shape of the surface. These new (quasi-static) surface configurations, known as vibroequilibria, can differ substantially from the hydrostatic state. There is a tendency for the interface to orient perpendicular to the vibrational axis and, in some cases, a bulge or cavity is induced

  17. Testing the gravitational instability hypothesis?

    NASA Technical Reports Server (NTRS)

    Babul, Arif; Weinberg, David H.; Dekel, Avishai; Ostriker, Jeremiah P.

    1994-01-01

    We challenge a widely accepted assumption of observational cosmology: that successful reconstruction of observed galaxy density fields from measured galaxy velocity fields (or vice versa), using the methods of gravitational instability theory, implies that the observed large-scale structures and large-scale flows were produced by the action of gravity. This assumption is false, in that there exist nongravitational theories that pass the reconstruction tests and gravitational theories with certain forms of biased galaxy formation that fail them. Gravitational instability theory predicts specific correlations between large-scale velocity and mass density fields, but the same correlations arise in any model where (a) structures in the galaxy distribution grow from homogeneous initial conditions in a way that satisfies the continuity equation, and (b) the present-day velocity field is irrotational and proportional to the time-averaged velocity field. We demonstrate these assertions using analytical arguments and N-body simulations. If large-scale structure is formed by gravitational instability, then the ratio of the galaxy density contrast to the divergence of the velocity field yields an estimate of the density parameter Omega (or, more generally, an estimate of beta identically equal to Omega(exp 0.6)/b, where b is an assumed constant of proportionality between galaxy and mass density fluctuations. In nongravitational scenarios, the values of Omega or beta estimated in this way may fail to represent the true cosmological values. However, even if nongravitational forces initiate and shape the growth of structure, gravitationally induced accelerations can dominate the velocity field at late times, long after the action of any nongravitational impulses. The estimated beta approaches the true value in such cases, and in our numerical simulations the estimated beta values are reasonably accurate for both gravitational and nongravitational models. Reconstruction tests

  18. Testing the gravitational instability hypothesis?

    NASA Astrophysics Data System (ADS)

    Babul, Arif; Weinberg, David H.; Dekel, Avishai; Ostriker, Jeremiah P.

    1994-05-01

    We challenge a widely accepted assumption of observational cosmology: that successful reconstruction of observed galaxy density fields from measured galaxy velocity fields (or vice versa), using the methods of gravitational instability theory, implies that the observed large-scale structures and large-scale flows were produced by the action of gravity. This assumption is false, in that there exist nongravitational theories that pass the reconstruction tests and gravitational theories with certain forms of biased galaxy formation that fail them. Gravitational instability theory predicts specific correlations between large-scale velocity and mass density fields, but the same correlations arise in any model where (a) structures in the galaxy distribution grow from homogeneous initial conditions in a way that satisfies the continuity equation, and (b) the present-day velocity field is irrotational and proportional to the time-averaged velocity field. We demonstrate these assertions using analytical arguments and N-body simulations. If large-scale structure is formed by gravitational instability, then the ratio of the galaxy density contrast to the divergence of the velocity field yields an estimate of the density parameter Omega (or, more generally, an estimate of beta identically equal to Omega0.6/b, where b is an assumed constant of