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Sample records for anterior scj instability

  1. Anterior Shoulder Instability with Concomitant Superior Labrum from Anterior to Posterior (SLAP) Lesion Compared to Anterior Instability without SLAP Lesion

    PubMed Central

    Durban, Claire Marie C.; Kim, Je Kyun; Kim, Sae Hoon

    2016-01-01

    Background The aims of this study were to investigate the clinical characteristics of patients with combined anterior instability and superior labrum from anterior to posterior (SLAP) lesions, and to analyze the effect of concomitant SLAP repair on surgical outcomes. Methods We retrospectively reviewed patients who underwent arthroscopic stabilization for anterior shoulder instability between January 2004 and March 2013. A total of 120 patients were available for at least 1-year follow-up. Forty-four patients with reparable concomitant detached SLAP lesions (group I) underwent combined SLAP and anterior stabilization, and 76 patients without SLAP lesions (group II) underwent anterior stabilization alone. Patient characteristics, preoperative and postoperative pain scores, Rowe scores, and shoulder ranges of motion were compared between the 2 groups. Results Patients in group I had higher incidences of high-energy trauma (p = 0.03), worse preoperative pain visual analogue scale (VAS) (p = 0.02), and Rowe scores (p = 0.04). The postoperative pain VAS and Rowe scores improved equally in both groups without significant differences. Limitation in postoperative range of motion was similar between the groups (all p-value > 0.05). Conclusions Anterior instability with SLAP lesion may not be related to frequent episodes of dislocation but rather to a high-energy trauma. SLAP fixation with anterior stabilization procedures did not lead to poor functional outcomes if appropriate surgical techniques were followed. PMID:27247742

  2. Recurrent anterior instability of the radial head: case report.

    PubMed

    Itadera, Eichi; Ueno, Keisuke

    2014-02-01

    We present a case of recurrent anterior instability of the radial head presenting 4 weeks after injury. A 16-year-old girl injured the right upper extremity while playing volleyball. Thereafter, she felt a recurrent click associated with pain in the elbow when rotating the forearm. Image intensifier findings implied that the radial head would anteriorly dislocate with contraction of the biceps brachii. Annular ligament reconstruction using the palmaris longus tendon graft relieved the instability. PMID:24332619

  3. 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. PMID:27049209

  4. 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

  5. Posterior shoulder pain and anterior instability: a preliminary clinical study.

    PubMed

    Castagna, Alessandro; Conti, Marco; Borroni, Mario; Massazza, Giuseppe; Vinci, Enzo; Franceschi, Giorgio; Garofalo, Raffaele

    2008-02-01

    Different clinical tests have been suggested in the literature as significant indicators of anterior shoulder instability. Sometimes patients with recurrent anterior shoulder instability may show some muscular guarding thus making the evaluation of specific clinical tests very difficult. These patients may also report a medical history with posterior shoulder pain that can be also elicited during some clinical manoeuvres. From September 2005 to September 2006 we prospectively studied patients who underwent an arthroscopic anterior capsuloplasty. Shoulder clinical examination was performed including anterior shoulder instability tests (drawer, apprehension and relocation tests). Furthermore the exam was focused on the presence of scapular dyskinesia and posterior shoulder pain. The patients were also evaluated with ASES, Rowe, SST (Simple Shoulder Test), Constant and UCLA (University of California at Los Angeles) scoring system preoperatively and at the latest follow-up time. In the period of this study we observed 16 patients treated for anterior gleno-humeral arthroscopic stabilisation, who preoperatively complained also of a posterior scapular pain. The pain was referred at the level of lower trapezium and upper rhomboids tendon insertion on the medial border of the scapula. It was also reproducible upon local palpation by the examiner. Four of these patients also referred pain in the region of the insertion of the infraspinatus and teres minor. After arthroscopic stabilisation the shoulder was immobilised in a sling with the arm in the neutral rotation for a period of 4 weeks. A single physician supervised shoulder rehabilitation. After a mean time of 6.8 months of follow-up, all the shoulder scores were significantly improved and, moreover, at the same time the patients referred the disappearance of the posterior pain. Posterior scapular shoulder pain seems to be another complaint and sign that can be found in patients affected by anterior shoulder instability

  6. Enlargement of Glenoid Defects in Traumatic Anterior Shoulder Instability

    PubMed Central

    Nakagawa, Shigeto; Ozaki, Ritsuro; Take, Yasuhiro; Mizuno, Naoko; Mae, Tatsuo

    2014-01-01

    Background: Large glenoid rim defects in patients with traumatic anterior shoulder instability are often regarded as a contraindication for arthroscopic Bankart repair, with a defect of 20% to 27% considered as the critical size. While recurrence of dislocations, male sex, and collision sports were reported to be the significant factors influencing large glenoid defects, the influences of subluxations and more detailed types of sports were not investigated. Purpose: To investigate the influence of the number of dislocations and subluxations and type of sport on the occurrence and size of glenoid defects in detail. Study Design: Case-control study; Level of evidence, 3. Methods: A total of 223 shoulders (60 with primary instability, 163 with recurrent instability) were prospectively examined by computed tomography. Glenoid rim morphology was compared between primary and recurrent instability. In patients with recurrent instability, the relationship between the glenoid defect and the number of dislocations and subluxations was investigated. In addition, glenoid defects were compared among 49 male American football players, 41 male rugby players, 27 male baseball players, and 25 female athletes. Results: The mean extent of the glenoid defect was 3.5% in shoulders with primary instability and 11.3% in those with recurrent instability. A glenoid defect was detected in 108 shoulders (66.2%) with recurrent instability versus 12 shoulders (20%) with primary instability. Regarding the influence of the total number of dislocations/subluxations, the average extent of the glenoid defect was 6.3% in 85 shoulders with 2 to 5 events, 12.9% in 34 shoulders with 6 to 10 events, and 19.6% in 44 shoulders with 11 or more events. The glenoid defect became significantly larger along with an increasing number of recurrences. Although recurrent subluxation without dislocation also influenced the glenoid defect size, the number of dislocations did not. The average extent of the glenoid

  7. 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.

  8. 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

  9. Arthroscopic Augmentation With Subscapularis Tendon in Anterior Shoulder Instability With Capsulolabral Deficiency

    PubMed Central

    Maiotti, Marco; Massoni, Carlo

    2013-01-01

    The treatment of chronic shoulder instability with poor quality of the anterior capsulolabral tissue is still controversial. In these cases the Latarjet procedure is certainly more effective in preventing recurrence than an arthroscopic capsular repair. However, several studies have reported a variety of severe complications related to the Latarjet procedure because of the use of bone augmentation and hardware implantation; moreover, the arthroscopic version of the Latarjet procedure is technically difficult and potentially dangerous because of the proximity of neurovascular structures. The aim of this report is to describe an innovative arthroscopic technique consisting of an augmentation of the anterior capsulolabral tissue using the articular portion of the subscapularis tendon and knotless suture anchors paired with high-strength tape for its fixation to the anterior glenoid edge. In the absence of severe bone deficiency of the anterior glenoid edge, this procedure can minimize arthroscopic technique failures, restoring the anterior capsulolabral wall without any significant reduction of shoulder functionality. PMID:24266004

  10. 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

  11. 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

  12. Iliac crest allograft glenoid reconstruction for recurrent anterior shoulder instability in athletes: Surgical technique and results

    PubMed Central

    Mascarenhas, Randy; Raleigh, Eden; McRae, Sheila; Leiter, Jeff; Saltzman, Bryan; MacDonald, Peter B.

    2014-01-01

    Performing a labral repair alone in patients with recurrent anterior instability and a large glenoid defect has led to poor outcomes. We present a technique involving the use of the iliac crest allograft inserted into the glenoid defect in athletes with recurrent anterior shoulder instability and large bony defects of the glenoid (>25% of glenoid diameter). All athletes with recurrent anterior shoulder instability and a large glenoid defect that underwent open anterior shoulder stabilization and glenoid reconstruction with the iliac crest allograft were followed over a 4-year period. Preoperatively, a detailed history and physical exam were obtained along with standard radiographs and magnetic resonance imaging of the affected shoulder. All patients also completed the Simple Shoulder Test (SST) and American Shoulder and Elbow Surgeons (ASES) evaluation forms preoperatively. A computed tomography scan was obtained postoperatively to assess osseous union of the graft and the patient again went through a physical exam in addition to completing the SST, ASES, and Western Ontario Shoulder Instability Index (WOSI) forms. 10 patients (9 males, 1 female) were followed for an average of 16 months (4–36 months) and had a mean age of 24.4 years. All patients exhibited a negative apprehension/relocation test and full shoulder strength at final follow-up. Eight of 10 patients had achieved osseous union at 6 months (80.0%). ASES scores improved from 64.3 to 97.8, and SST scores improved from 66.7 to 100. Average postoperative WOSI scores were 93.8%. The use of the iliac crest allograft provides a safe and clinically useful alternative compared to previously described procedures for recurrent shoulder instability in the face of glenoid deficiency. PMID:25538432

  13. 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

  14. [Classification of anterior instability of the shoulder by arthroscopy - the authors clinical material.].

    PubMed

    Masár, J; Petriscák, S

    1997-01-01

    The authors review briefly the evaluation of anterior instability of the shoulder joint from different aspects. The objective of their work was to present different types of morphological changes, as suggested by Resch (6). During the two-year period since June 1995 so far a total of 96 patients with the clinical picture of anterior instability of the humeroscapular joint were examined arthroscopically. The group comprised 69 men and 27 women, all in productive age. Type 1 lesions according to Resch were found in 52 %, type 2 in 21 %, type 3 in 6 %, type 4 in 13 %, type 5 in 1 % and type 6 in 7 % of the patients, which is consistent with data reported in the literature. In their opinion type 5 lesions are most difficult to diagnose. A certain amount of routine is needed also to differentiate type 1 and 4 and type 2 and 6 according to Resch's classification. Conversely, they consider type 3 findings standard and unequivocal. Key words: humeroscapular joint, anterior instability, arthroscopic diagnosis, type of lesions. PMID:20470642

  15. Factors Affecting Return to Baseline Function at 6 months Following Anterior Shoulder Instability Surgery

    PubMed Central

    Hettrich, Carolyn M.; Buckwalter, Joseph; Wolf, Brian R.; Bollier, Matthew; MOON, Shoulder Group; Glass, Natalie

    2016-01-01

    Objectives: Pre-operative and surgical factors related to early return to baseline function after anterior shoulder instability surgery are not clear. This study was designed to determine the pre-operative and operative factors affecting return to baseline function at 6 months following anterior shoulder instability surgery. Identifying these factors will help surgeons establish expectations for functional return post-operatively. Methods: The Multicenter Orthopaedic Outcomes Network (MOON) shoulder group enrolled patients undergoing surgery for shoulder instability from 16 sites throughout the United States. Initial demographic data and validated, patient-oriented outcomes questionnaires were collected along with the physicians documented initial physical exam, treatment, surgical findings and surgical techniques used at the time of surgery. At the 6-month follow up visit, range of motion (ROM) and strength measurement of the operative shoulder were collected and compared to pre-operative measurement. Return to baseline was defined as return to within -10° ROM and full strength at the 6 month physical exam. Continuous and categorical data were analyzed using student t-tests and chi-square tests, respectively. The Kruskal-Wallis/Wilcoxin tests were used to compare groups that were not normally distributed. Factors reaching significance in a univariate analysis were then applied in a multivariable model. Significance was set a p<0.05. Results: A total of 338 patients with history of surgical intervention for anterior instability of the shoulder were identified. 278 patients had complete pre- and post-surgical range of motion and strength measurements. 138 (50%) patients (139 shoulders) returned to baseline and 133 (50%) patients did not return to baseline. Univariate analysis identified age (p=0.0013), Beighton score (p=0.0004), SF-36 general health (p=0.0017), WOSI (p=0.0250), and duration of symptoms (p=0.0046) as significant factors. When these factors were

  16. Arthroscopic anterior talofibular ligament repair for lateral instability of the ankle.

    PubMed

    Takao, Masato; Matsui, Kentaro; Stone, James W; Glazebrook, Mark A; Kennedy, John G; Guillo, Stephane; Calder, James D; Karlsson, Jon

    2016-04-01

    Although several arthroscopic procedures for lateral ligament instability of the ankle have been reported recently, it is difficult to augment the reconstruction by arthroscopically tightening the inferior extensor retinaculum. There is also concern that when using the inferior extensor retinaculum, this is not strictly an anatomical repair since its calcaneal attachment is different to that of the calcaneofibular ligament. If a ligament repair is completed firmly, it is unnecessary to add argumentation with inferior extensor retinaculum. The authors describe a simplified technique, repair of the lateral ligament alone using a lasso-loop stitch, which avoids additionally tighten the inferior extensor retinaculum. In this paper, it is described an arthroscopic anterior talofibular ligament repair using lasso-loop stitch alone for lateral instability of the ankle that is likely safe for patients and minimal invasive. Level of evidence Therapeutic study, Level V. PMID:25982624

  17. 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

  18. Recurrent anterior shoulder instability: Review of the literature and current concepts

    PubMed Central

    Sofu, Hakan; Gürsu, Sarper; Koçkara, Nizamettin; Öner, Ali; Issın, Ahmet; Çamurcu, Yalkın

    2014-01-01

    The purpose of this review article is to discuss the clinical spectrum of recurrent traumatic anterior shoulder instability with the current concepts and controversies at the scientific level. Because of increasing participation of people from any age group of the population in sports activities, health care professionals dealing with the care of trauma patients must have a thorough understanding of the anatomy, patho-physiology, risk factors, and management of anterior shoulder instability. The risk factors for recurrent shoulder dislocation are young age, participation in high demand contact sports activities, presence of Hill-Sachs or osseous Bankart lesion, previous history of ipsilateral traumatic dislocation, ipsilateral rotator cuff or deltoid muscle insufficiency, and underlying ligamentous laxity. Achieving the best result for any particular patient depends on the procedure that allows observation of the joint surfaces, provides the anatomical repair, maintains range of motion, and also can be applied with low rates of complications and recurrence. Although various surgical techniques have been described, a consensus does not exist and thus, orthopedic surgeons should follow and try to improve the current evidence-based treatment modalities for the patients. PMID:25405191

  19. 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

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

    PubMed

    Ramhamadany, Eamon; Modi, Chetan S

    2016-06-18

    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

  1. Gene expression analysis in patients with traumatic anterior shoulder instability suggests deregulation of collagen genes.

    PubMed

    Belangero, Paulo Santoro; Leal, Mariana Ferreira; Figueiredo, Eduardo Antônio; Cohen, Carina; Pochini, Alberto de Castro; Smith, Marília Cardoso; Andreoli, Carlos Vicente; Belangero, Sintia Iole; Ejnisman, Benno; Cohen, Moises

    2014-10-01

    Shoulder dislocation occurs in 1-2% of the population. Capsular deformation is a key factor in shoulder dislocation; however, little is known about capsule biology. We evaluated, for the first time in literature, the expression of COL1A1, COL1A2, COL3A1 and COL5A1 in the antero-inferior, antero-superior and posterior regions of the glenohumeral capsule of 31 patients with anterior shoulder instability and eight controls. The expression of collagen genes was evaluated by quantitative reverse transcription-PCR. The expression of COL1A1, COL3A1 and the ratio of COL1A1/COL1A2 were increased in all three portions of the capsule in patients compared to controls (p < 0.05). COL1A2 expression was upregulated in the antero-superior and posterior sites of the capsule of patients (p < 0.05). The ratio of COL1A2/COL3A1 expression was reduced in capsule antero-inferior and posterior sites of patients compared to controls (p < 0.05). In the capsule antero-inferior site of patients, the ratios of COL1A1/COL5A1, CO1A2/COL5A1 and COL3A1/COL5A1 expression were increased (p < 0.05). In patients, COL1A1/COL5A1 was also increased in the posterior site (p < 0.05). We found deregulated expression of collagen genes across the capsule of shoulder instability patients. These molecular alterations may lead to modifications of collagen fibril structure and impairment of the healing process, possibly with a role in capsular deformation. PMID:25042113

  2. Biomechanical Comparison of Acute Hill-Sachs Reduction and Remplissage to Treat Complex Anterior Instability

    PubMed Central

    Dines, Joshua S.; Garcia, Grant; McGarry, Michelle H.; Lee, Thay Q.; Degen, Ryan

    2016-01-01

    Objectives: Acute Hill-Sachs (HS) reduction represents a potential alternative method to remplissage for the treatment of an engaging HS lesion. The purpose of this study is to biomechanically compare the stabilizing effects of an acute HS reduction technique and remplissage in a complex instability model. Methods: This was a comparative cadaveric study of 6 shoulders. For the acute HS lesion, a unique model was used to create a 30% defect, compressing the subchondral bone while preserving the articular surface in a more anatomic fashion. In addition, a 15% glenoid defect was made in all specimens. The HS lesion was reduced through a lateral cortical window with a bone tamp, and the subchondral void was filled with Quickset (Arthrex) bone cement to prevent plastic deformation. Five scenarios were tested; intact specimen, bipolar lesion, Bankart repair, remplissage with Bankart repair and HS reduction technique with Bankart repair. Translation, kinematics and dislocation events were recorded. Results: For all 6 specimens no dislocations occurred after either remplissage or the reduction technique. At 90 degrees of abduction and external rotation (ABER), anterior-inferior translation was 11.1 mm (SD 0.9) for the bipolar lesion. This was significantly reduced following both remplissage (5.1±0.7 mm; p<0.001) and HS reduction (4.4 ±0.3 mm; p<0.001). For anterior-inferior translation there was no significant difference in translation between the reduction technique and remplissage (p=0.91). At 90 degrees of ABER, the intact specimens average joint stiffness was 7.0 ±1.0N/mm, which was not significantly different from the remplissage (7.8±0.9 N/mm; p=0.9) and reduction technique (9.1±0.6 N/mm; p=0.50). Compared with an isolated Bankart repair, the average external rotation loss after also performing a remplissage procedure was 4.3 ±3.5 deg (p=0.65), while average ER loss following HS reduction was 1.1 ±3.3 deg (p=0.99). There was no significant difference in

  3. 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.

  4. 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. PMID:23314981

  5. 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

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

    PubMed Central

    Trč, Tomáš; Handl, Milan

    2010-01-01

    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. PMID:20431880

  7. Expression analysis of genes involved in collagen cross-linking and its regulation in traumatic anterior shoulder instability.

    PubMed

    Belangero, Paulo Santoro; Leal, Mariana Ferreira; Cohen, Carina; Figueiredo, Eduardo Antônio; Smith, Marília Cardoso; Andreoli, Carlos Vicente; de Castro Pochini, Alberto; Ejnisman, Benno; Cohen, Moises

    2016-03-01

    The molecular alterations involved in the capsule deformation presented in shoulder instability patients are poorly understood. Increased TGFβ1 acts as a signal for production of matrix macromolecules by fibrogenic cells at joint injury sites. TGFβ1, through its receptor TGFβR1, regulates genes involved in collagen cross-linking, such as LOX, PLOD1, and PLOD2. We evaluated TGFβ1, TGFβR1, LOX, PLOD1, and PLOD2 gene expression in the antero-inferior (macroscopically injured region), antero-superior and posterior regions of the glenohumeral capsule of 29 shoulder instability patients and eight controls. We observed that PLOD2 expression was increased in the anterior-inferior capsule region of the patients compared to controls. LOX expression tended to be increased in the posterior portion of patients. Patients with recurrent shoulder dislocation presented upregulation of TGFβR1 in the antero-inferior capsule portion and of PLOD2 in the posterior region. Conversely, LOX was increased in the posterior portion of the capsule of patients with a single shoulder dislocation episode. In the antero-inferior, LOX expression was inversely correlated and TGFβR1 was directly correlated with the duration of symptoms. In the posterior region, PLOD2, TGFβ1, and TGFβR1 were directly correlated with the duration of symptoms. In conclusion, PLOD2 expression was increased in the macroscopically injured region of the capsule of patients. Upregulation of TGFβ1, TGFβR1, and PLOD2 seems to be related with the maintenance of disease symptoms, especially in the posterior region. LOX upregulation seems to occur only in the initial phase of the affection. Therefore, TGFβ1, TGFβR1, LOX, and PLOD2 may play a role in shoulder instability. PMID:26185036

  8. 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. PMID:26241404

  9. EVALUATION OF THE RESULTS FROM ARTHROSCOPIC SURGICAL TREATMENT FOR TRAUMATIC ANTERIOR SHOULDER INSTABILITY USING SUTURING OF THE LESION AT THE OPENED MARGIN OF THE GLENOID CAVITY

    PubMed Central

    Miyazaki, Alberto Naoki; Fregoneze, Marcelo; Santos, Pedro Doneux; da Silva, Luciana Andrade; do Val Sella, Guilherme; Duarte, Clodoaldo; Botelho, Vinícius; Checchia, Sergio Luiz

    2015-01-01

    Objective: To evaluate the clinical results from patients with traumatic anterior shoulder instability that was treated surgically through arthroscopic viewing, using bioabsorbable anchors and a technique for remove the cartilage of the anterior glenoid rim for repairing a Bankart lesion. Method: Between March 2006 and October 2008, 27 shoulders in 27 patients with a diagnosis of traumatic anterior shoulder instability were operated. The patients’ mean age was 28 years and they had had between two and 25 previous episodes of dislocation. The patients were predominantly male (24; 89%). The minimum length of follow-up was 24 months and the mean was 36 months. None of the patients had previously undergone surgery on the affected shoulder or had any significant bone lesion at the glenoid margin. The postoperative clinical assessment was done using the Rowe scale. To measure the preoperative and postoperative joint range of motion, we used the method described by the American Academy of Orthopaedic Surgeons (AAOS). Results: According to the Rowe criteria, 25 patients (93%) achieved excellent results and two (7%) had poor results. None of the patients presented good or fair results. Twenty-three patients were satisfied with the results obtained (85%), and returned to their activities without limitations, while four patients (15%) had some degree of limitation. There was recurrence of instability in two patients (7%). Conclusion: Treatment of traumatic anterior shoulder instability through arthroscopic viewing using a technique for remove the cartilage of the anterior glenoid rim for repairing a Bankart lesion provided excellent results for 93% of the patients operated. PMID:27042640

  10. Can we improve radiological analysis of osseous lesions in chronic anterior shoulder instability?

    PubMed

    Charousset, C; Beauthier, V; Bellaïche, L; Guillin, R; Brassart, N; Thomazeau, H

    2010-12-01

    Osseous lesions of the glenoid cavity and humeral head are predictive of recurrence after Bankart arthroscopic procedures. The objective of this study was to analyze, for each glenoid and humeral defect plain x-ray criteria of the Instability Severity Index Score (ISIS), two aspects: inter- and intraobserver reliability of their qualitative and quantitative assessment and correlations between positive criteria and their quantitative measurement. Thirty-one medical files were retained for evaluation of the glenoid and 26 for humeral notch assessment. The yes or no response for the ISIS criterion was completed by its quantitative measurement using the Griffiths and Sugaya CT methods for the glenoid and the P/R index calculation on plain x-rays with internal rotation for the Hill-Sachs lesion. Three observers provided two consecutive readings for each criterion. The analysis of the glenoid radiological criterion of the ISIS seems sufficiently reproducible for daily practice. When the evaluation is positive, bone loss is greater than 15%, without a maximum value established. In this study, the analysis of the ISIS humeral notch criterion was not reproducible. It can be improved using the P/R index and should be completed by CT imaging. PMID:21035420

  11. “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

  12. 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

  13. Ultrasonography in the Assessment of Lateral Ankle Ligament Injury, Instability, and Anterior Ankle Impingement: A Diagnostic Case Report

    PubMed Central

    Battaglia, Patrick J.; Craig, Kate; Kettner, Norman W.

    2015-01-01

    Objective The purpose of this case report is to describe the diagnostic value of ultrasonography (US) in a patient with injury to the lateral ligaments of the ankle with concomitant ankle joint osteoarthritis and anterior impingement. Clinical Features A 28-year-old male had a history of an inversion injury of the left ankle. Diagnostic US of the left ankle using an 8- to 15-MHz linear array transducer demonstrated a full thickness tear of the anterior talofibular ligament, partial thickness tearing of the calcaneofibular ligament, and laxity of the ankle with varus stress testing. In addition, US was able to demonstrate degeneration of the ankle and talonavicular joints and anterior impingement with dorsiflexion. Osteoarthritic changes were confirmed with radiography. Other US findings included remote deltoid ligamentous complex injury, multiple sites of tenosynovitis, and a large ankle joint effusion with synovial hypertrophy and synovitis. Intervention and Outcome Using US, an accurate diagnosis was established with respect to the pathology and functional impairments of the patient’s ankle. Conclusion This case report exemplifies the value and utility of US in diagnosing derangement in ligamentous, tendinous, articular, and osseous injuries of the ankle. PMID:26793038

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

    PubMed Central

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

    2014-01-01

    Background: 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. Methods: 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. Results: 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). Conclusions: 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. PMID:25386585

  15. Reconstruction of the anterior cruciate ligament with the iliotibial band autograft in patients with chronic knee instability.

    PubMed

    Jørgensen, U; Bak, K; Ekstrand, J; Scavenius, M

    2001-05-01

    We performed combined internal and external anterior cruciate ligament (ACL) reconstruction with the iliotibial band autograft in 169 consecutive patients with chronic ACL insufficiency who were followed up for 24-61 months. Of these, 155 (91%) agreed to an additional independent observer follow-up after 24-92 months. Eight patients (5%) had sustained a rerupture/elongation of the graft and were operated on again; nine (6%) had sustained a tear of the contralateral ACL. Knee function and activity increased after the reconstruction. Lysholm scores improved from median 81 preoperatively to 99 at follow-up and Tegner scores from median 4 to 7. At follow-up 97 (71%) were active at the same level as prior to injury. In 17 of the 40 patients (12%) dropping to a lower activity level this was due to knee problems. The side-to-side difference in anterior-posterior knee laxity was more than 3 mm in 18 knees (13%) and more than 5 mm in 3 knees (2%). Including eight reruptures, this results in a "stability" failure rate of 8.8%. The overall IKCD rating showed normal knee function in 88 (73%) and nearly normal knee function in 30 (25%). Anterior knee pain was present in 14 (10%) of the patients at follow-up. Patients with isolated ACL injury had higher Lysholm scores and Tegner scores than patients with associated injuries. No clinical signs of varus knee development were seen. Of the 155 patients 94% would have the procedure repeated if necessary with the knowledge that they have today. The combined internal and external iliotibial band procedure can restore knee stability and function in the majority of chronic ACL-insufficient knees. PMID:11420786

  16. Hip instability.

    PubMed

    Smith, Matthew V; Sekiya, Jon K

    2010-06-01

    Hip instability is becoming a more commonly recognized source of pain and disability in patients. Traumatic causes of hip instability are often clear. Appropriate treatment includes immediate reduction, early surgery for acetabular rim fractures greater than 25% or incarcerated fragments in the joint, and close follow-up to monitor for avascular necrosis. Late surgical intervention may be necessary for residual symptomatic hip instability. Atraumatic causes of hip instability include repetitive external rotation with axial loading, generalized ligamentous laxity, and collagen disorders like Ehlers-Danlos. Symptoms caused by atraumatic hip instability often have an insidious onset. Patients may have a wide array of hip symptoms while demonstrating only subtle findings suggestive of capsular laxity. Traction views of the affected hip can be helpful in diagnosing hip instability. Open and arthroscopic techniques can be used to treat capsular laxity. We describe an arthroscopic anterior hip capsular plication using a suture technique. PMID:20473129

  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. 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 Central

    Merolla, Giovanni; Porcellini, Giuseppe

    2014-01-01

    Principal investigator and promoter: 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”) PMID:24809031

  19. 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

  20. Tibialis Anterior Tendon Transfer.

    PubMed

    Mulhern, Jennifer L; Protzman, Nicole M; Brigido, Stephen A

    2016-01-01

    Tendon transfer procedures are used commonly for the correction of soft tissue imbalances and instabilities. The complete transfer and the split transfer of the tibialis anterior tendon are well-accepted methods for the treatment of idiopathic equinovarus deformity in children and adults. Throughout the literature, complete and split transfer have been shown to yield significant improvements in ankle and foot range of motion and muscle function. At present, there is insufficient evidence to recommend one procedure over the other, although the split procedure has been advocated for consistently achieving inversion to eversion muscle balance without overcorrection. PMID:26590723

  1. Dynamic ultrasound of peroneal tendon instability.

    PubMed

    Pesquer, Lionel; Guillo, Stéphane; Poussange, Nicolas; Pele, Eric; Meyer, Philippe; Dallaudière, Benjamin

    2016-07-01

    Ankle snapping may be caused by peroneal tendon instability. Anterior instability occurs after traumatic superior peroneal retinaculum injury, whereas peroneal tendon intrasheath subluxation is atraumatic. Whereas subluxation is mainly dynamic, ultrasound allows for the diagnosis and classification of peroneal instability because it allows for real-time exploration. The purpose of this review is to describe the anatomic and physiologic bases for peroneal instability and to heighten the role of dynamic ultrasound in the diagnosis of snapping. PMID:26943704

  2. 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

  3. Shoulder instability surgery in Norway

    PubMed Central

    2012-01-01

    Background and purpose In January 2008, we established the Norwegian Register for Shoulder Instability Surgery. We report on the establishment, the baseline data, and the results at 1-year follow-up. Methods Primary and revision shoulder stabilization is reported by the surgeon on a 1-page paper form containing the patient's history of shoulder injury, clinical findings, and perioperative findings. The WOSI questionnaire for self-assessment of shoulder function is completed at baseline and at follow-up after 1, 2, and 5 years. To evaluate the completeness of registration, we compared our data with those in the Norwegian Patient Registry (NPR). Results The NPR reported 39 hospitals performing shoulder stabilizations. 20 of these started to report to our register during 2009, and 464 procedures (404 primary, 59 revisions) were included up to December 31, 2009, which represented 54% of the procedures reported to NPR. Of the 404 primary procedures, 83% were operations due to anterior instability, 10% were operations due to posterior instability, and 7% were operations due to multidirectional instability. Arthroscopic soft tissue techniques were used in 88% of the patients treated for primary anterior instability and open coracoid transfer was used in 10% of such patients. At 1-year follow-up of 213 patients, we found a statistically significantly improved WOSI score in all types of instability. 10% of the patients treated with arthroscopic anterior labral repair and 16% treated with arthroscopic posterior labral repair reported recurrent instability. No statistically significant difference in functional improvement or rate of recurrence was found between these groups. Interpretation The functional results are in accordance with those in previous studies. However, the incidence of recurrent instability 1 year after arthroscopic labral repair is higher than expected. PMID:22112155

  4. Shoulder Instability

    MedlinePlus

    ... Risk Factors Is shoulder instability the same as shoulder dislocation? No. The signs of dislocation and instability might ... the same to you--weakness and pain. However, dislocation occurs when your shoulder goes completely out of place. The shoulder ligaments ...

  5. Phacoemulsification in anterior megalophthalmos.

    PubMed

    Lee, Graham A; Hann, Joshua V; Braga-Mele, Rosa

    2006-07-01

    This case outlines the phacoemulsification technique used to overcome the challenge of the hyperdeep anterior chamber, weak zonules, abnormal anterior capsule, and large capsular bag. Key steps included trypan blue staining of the anterior capsule, a large capsulorhexis, prolapse of the nucleus into the anterior chamber with phacoemulsification anterior to the capsulorhexis, and a posterior chamber-placed iris-clip intraocular lens. Successful visual rehabilitation is achievable in these anatomically challenging eyes. PMID:16857490

  6. Anterior vaginal wall repair

    MedlinePlus

    ... Cystocele Anterior vaginal wall repair (surgical treatment of urinary incontinence) - series References Lentz GM. Anatomic defects of the ... 72. Read More Anterior Inflatable artificial sphincter Stress urinary incontinence Urinary catheters Urinary incontinence - injectable implant Urinary incontinence - ...

  7. 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.

  8. [Arthroscopic tightening of the anterior cruciate ligament].

    PubMed

    Charrois, O; Cheyrou, E; Remi, J; Panarella, L; Jouve, F; Beaufils, P

    2008-02-01

    We present here the preliminary results obtained with arthroscopic tightening of the anterior cruciate ligament. Six patients underwent the technique. Four had had prior ligamentoplasty, two had sequelae of tibial spine fractures. Laxity persisted in all cases. The transplant or the ligament were continuous and insertion points were well-positioned. The procedure consisted in using a trephine to bore the tibial bone at the "foot" of the ligament or transplant in order to tighten the ligament. There was no evidence of instability after the arthroscopic tightening procedure. Mean pre- and postoperative differential anterior drawer values were successively 9.2 and 3.9 mm. For native or reconstructed anterior cruciate ligaments, which are continuous and well-positioned but not loose, arthroscopic tightening spares the need for ligament transplant and appears to be free of specific morbidity. PMID:18342033

  9. 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. PMID:27543398

  10. [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. PMID:19268113

  11. Bipolar bone defect in the shoulder anterior dislocation.

    PubMed

    Di Giacomo, Giovanni; de Gasperis, Nicola; Scarso, Paolo

    2016-02-01

    In the anterior shoulder instability with glenoid bone loss among 25 % or more of the inferior glenoid diameter (inverted-pear glenoid), the consensus of recent authors is that glenoid bone grafting (Latarjet procedure) should be performed. The engaging Hill-Sachs lesion has been recognized as a risk factor for recurrent anterior shoulder instability. We have developed a method using radiographic and arthroscopic studies and the concept of the glenoid track to determine whether a Hill-Sachs lesion will engage the anterior glenoid rim, whether or not there is concomitant anterior glenoid bone loss. If the Hill-Sachs lesion engages, it is called an "off-track" Hill-Sachs lesion; if it does not engage, it is an "on-track" lesion. On the basis of our quantitative method, we have developed a treatment paradigm with specific surgical criteria for all patients with anterior shoulder instability (first dislocation or recurrent dislocation), both with and without bipolar bone loss. PMID:26704802

  12. 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.

  13. Hybrid rocket instability

    NASA Astrophysics Data System (ADS)

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

    1993-06-01

    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.

  14. 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

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

    PubMed Central

    Morell, Daniel J; Thyagarajan, David S

    2016-01-01

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

  16. 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

  17. Congenital anterior urethral diverticulum.

    PubMed

    Singh, Sanjeet Kumar; Ansari, Ms

    2014-09-01

    Congenital anterior urethral diverticulum (CAUD) may be found all along the anterior urethra and may present itself at any age, from infant to adult. Most children with this condition present with difficulty in initiating micturition, dribbling of urine, poor urinary stream, or urinary tract infection. A careful history will reveal that these children never had a good urinary stream since birth, and the telltale sign is a cystic swelling of the penile urethra. In this paper, we present two cases of CAUD that were managed by excision of the diverticulum with primary repair. PMID:26328174

  18. 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.

  19. [Toxic anterior segment syndrome].

    PubMed

    Cornut, P-L; Chiquet, C

    2011-01-01

    Toxic anterior segment syndrome (TASS) is a general term used to describe acute, sterile postoperative inflammation due to a non-infectious substance that accidentally enters the anterior segment at the time of surgery and mimics infectious endophthalmitis. TASS most commonly occurs acutely following anterior segment surgery, typically 12-72h after cataract extraction. Anterior segment inflammation is usually quite severe with hypopyon. Endothelial cell damage is common, resulting in diffuse corneal edema. No bacterium is isolated from ocular samples. The causes of TASS are numerous and difficult to isolate. Any device or substance used during the surgery or in the immediate postoperative period may be implicated. The major known causes include: preservatives in ophthalmic solutions, denatured ophthalmic viscosurgical devices, bacterial endotoxin, and intraocular lens-induced inflammation. Clinical features of infectious and non-infectious inflammation are initially indistinguishable and TASS is usually diagnosed and treated as acute endophthalmitis. It usually improves with local steroid treatment but may result in chronic elevation of intraocular pressure or irreversible corneal edema due to permanent damage of trabecular meshwork or endothelial cells. PMID:21176994

  20. Understanding Multidirectional Instability of the Shoulder

    PubMed Central

    Cordasco, Frank A.

    2000-01-01

    Objective: To provide an overview of the evaluation and treatment of the patient with multidirectional shoulder instability. Data Sources: I searched MEDLINE for the years from 1980 to 2000 using the key words “shoulder joint,” “instability,” “dislocation,” “multidirectional shoulder instability,” and “inferior capsular shift.” Data Synthesis: Multidirectional instability is symptomatic glenohumeral subluxation or dislocation in more than 1 direction: anterior, inferior, or posterior. The primary pathology is a loose and patulous capsule, and the entity is more common than previously recognized. Multidirectional instability affects young, sedentary patients with generalized ligamentous laxity, often with bilateral symptoms and an atraumatic history, but it also affects athletes, many of whom have sustained injuries. Patients with multidirectional instability may also have Bankart lesions and humeral head impression defects. Conclusions/Recommendations: Patients with multidirectional instability must be identified before appropriate treatment can be initiated. If a course of rehabilitation fails to improve the patient's symptoms, an inferior capsular shift procedure has been demonstrated to be an effective surgical option. ImagesFigure 1.Figure 2.Figure 3.Figure 4.Figure 5.Figure 6.Figure 7.Figure 8.Figure 9.Figure 10. PMID:16558641

  1. Arthroscopic Reverse Remplissage for Posterior Instability.

    PubMed

    Lavender, Chad D; Hanzlik, Shane R; Pearson, Sara E; Caldwell, Paul E

    2016-02-01

    Posterior shoulder dislocation is an unusual injury often associated with electrical shock or seizure. As with anterior instability, patients frequently present with an impaction injury to the anterior aspect of the humeral head known as a "reverse Hill-Sachs lesion." The treatment of this bony defect is controversial, and multiple surgical procedures to fill the defect in an effort to decrease recurrence have been described. Most of the reports have focused on an open approach using variations of lesser tuberosity and subscapularis transfers, bone allograft, and even arthroplasty to assist with persistent instability. We advocate an arthroscopic technique that involves a suture anchor-based distal tenodesis of the subscapularis tendon or a reverse remplissage procedure. PMID:27073776

  2. Arthroscopic Reverse Remplissage for Posterior Instability

    PubMed Central

    Lavender, Chad D.; Hanzlik, Shane R.; Pearson, Sara E.; Caldwell, Paul E.

    2016-01-01

    Posterior shoulder dislocation is an unusual injury often associated with electrical shock or seizure. As with anterior instability, patients frequently present with an impaction injury to the anterior aspect of the humeral head known as a “reverse Hill-Sachs lesion.” The treatment of this bony defect is controversial, and multiple surgical procedures to fill the defect in an effort to decrease recurrence have been described. Most of the reports have focused on an open approach using variations of lesser tuberosity and subscapularis transfers, bone allograft, and even arthroplasty to assist with persistent instability. We advocate an arthroscopic technique that involves a suture anchor–based distal tenodesis of the subscapularis tendon or a reverse remplissage procedure. PMID:27073776

  3. Anterior mandibular ameloblastoma

    PubMed Central

    Bhandarwar, Ajay H.; Bakhshi, Girish D.; Borisa, Ashok D.; Wagh, Amol; Kapoor, Rajat; Kori, Channabasappa G.

    2012-01-01

    Ameloblastoma is a benign odontogenic tumor. These are usually asymptomatic until a large size is attained. Ameloblastoma has tendency to spread locally and has a high recurrence rate. Majority of ameloblastomas (80%) arise from the mandible. Ameloblastoma arising from anterior mandibular region (symphysis-menti) is rare. Very few cases of midline anterior ameloblastomas are reported in the literature. They often require wide local excision. Reconstruction of mandible in these cases is challenging. We present a case of mandibular ameloblastoma arising from symphysis-menti. Patient underwent wide surgical excision of the tumor followed by immediate reconstruction using free fibular vascular flap, stabilized with titanium reconstructive plates. A brief case report ands review of literature is presented. PMID:24765429

  4. Anterior urethral stricture review

    PubMed Central

    Stein, Marshall J.

    2013-01-01

    Male anterior urethral stricture disease is a commonly encountered condition that presents to many urologists. According to a National Practice Survey of Board Certified Urologist in the United States most urologists treat on average 6-20 urethral strictures yearly. Many of those same urologists surveyed treat with repeated dilation or internal urethrotomy, despite continual recurrence of the urethral stricture. In point of fact, the urethroplasty despite its high success rate, is underutilized by many practicing urologists. Roughly half of practicing urologist do not perform urethroplasty in the United States. Clearly, the reconstructive ladder for urethral stricture management that was previously described in the literature may no longer apply in the modern era. The following article reviews the etiology, diagnosis, management and comparisons of treatment options for anterior urethral strictures. PMID:26816721

  5. Anterior perineal sinus.

    PubMed

    Oliver, G C; Rubin, R J; Salvati, E P; Eisenstat, T E; Lott, J

    1991-09-01

    Each year we treat several patients with an anterior perineal sinus tract. They do not conform to commonly encountered perineal problems such as pilonidal disease, epidermal cysts, hidradenitis, fistulous abscess, or inflammatory bowel disease. In an effort to improve understanding of the problem and its clinical significance, we reviewed our practice records for the period from 1968 through 1988. Fifty-six patients underwent surgery for an anterior perineal sinus tract. In 31 patients, the clinical and pathologic condition defied classical diagnostic categorization. We have termed these lesions "anterior perineal sinuses." Their clinical characteristics, treatment, and pathologic assessment from the body of this report. Male predominance (87 percent) and midlife presentation (average age, 44 years) characterized this group. Local symptoms were present from several weeks to several years prior to treatment. Local anesthesia (74 percent) and limited surgery (100 percent) resulted in complete healing in all patients (average, 7 weeks). A 15 percent recurrence rate was noted. The pathologic evaluation demonstrated acute and chronic dermal and subcutaneous inflammation. The etiology of this process remains uncertain. Its predominance along the median raphe suggests a congenital midline inclusion disorder. PMID:1914743

  6. 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. PMID:22959195

  7. Anterior Hip Joint Force Increases with Hip Extension, Decreased Gluteal Force, or Decreased Iliopsoas Force

    PubMed Central

    Lewis, Cara L.; Sahrmann, Shirley A.; Moran, Daniel W.

    2008-01-01

    Abnormal or excessive force on the anterior hip joint may cause anterior hip pain, subtle hip instability and a tear of the acetabular labrum. We propose that both the pattern of muscle force and hip joint position can affect the magnitude of anterior joint force and thus possibly lead to excessive force and injury. The purpose of this study was to determine the effect of hip joint position and of weakness of the gluteal and iliopsoas muscles on anterior hip joint force. We used a musculoskeletal model to estimate hip joint forces during simulated prone hip extension and supine hip flexion under 4 different muscle force conditions and across a range of hip extension and flexion positions. Weakness of specified muscles was simulated by decreasing the modeled maximum force value for the gluteal muscles during hip extension and the iliopsoas muscle during hip flexion. We found that decreased force contribution from the gluteal muscles during hip extension and the iliopsoas muscle during hip flexion resulted in an increase in the anterior hip joint force. The anterior hip joint force was greater when the hip was in extension than when the hip was in flexion. Further studies are warranted to determine if increased utilization of the gluteal muscles during hip extension and of the iliopsoas muscle during hip flexion, and avoidance of hip extension beyond neutral would be beneficial for people with anterior hip pain, subtle hip instability, or an anterior acetabular labral tear. PMID:17707385

  8. Knee instability scores for ACL reconstruction.

    PubMed

    Rahnemai-Azar, Ata A; Naendrup, Jan-Hendrik; Soni, Ashish; Olsen, Adam; Zlotnicki, Jason; Musahl, Volker

    2016-06-01

    Despite abundant biological, biomechanical, and clinical research, return to sport after anterior cruciate ligament (ACL) injury remains a significant challenge. Residual rotatory knee laxity has been identified as one of the factors responsible for poor functional outcome. To improve and standardize the assessment of knee instability, a variety of instability scoring systems is available. Recently, devices to objectively quantify static and dynamic clinical exams have been developed to complement traditional subjective grading systems. These devices enable an improved evaluation of knee instability and possible associated injuries. This additional information may promote the development of new treatment algorithms and allow for individualized treatment. In this review, the different subjective laxity scores as well as complementary objective measuring systems are discussed, along with an introduction of injury to an individualized treatment algorithm. PMID:26980119

  9. Elbow joint instability: A kinematic model.

    PubMed

    Olsen, B S; Henriksen, M G; Søjbjerg, J O; Helmig, P; Sneppen, O

    1994-05-01

    The effect of simultaneous ulnar and radial collateral ligament division on the kinematics of the elbow joint is studied in a cadaveric model. Severance of the anterior part of the ulnar collateral ligament and the annular ligament led to significant elbow joint instability in valgus and varus stress and in forced external and internal rotation. The mean maximum laxity in valgus stress and forced external rotation were 5.7° and 13.2°. The forearms of the elbow joint specimens were transfixed in maximum pronation. During valgus and varus stress the corresponding spontaneous ulnar rotation of the specimens was recorded. The reproducibility of the instability pattern suggests that this model is suitable for evaluating stabilizing procedures aimed at correction of elbow joint instability before these procedures are introduced into patient care. PMID:22959690

  10. Anterior cruciate ligament rupture and osteoarthritis progression.

    PubMed

    Wong, James Min-Leong; Khan, Tanvir; Jayadev, Chethan S; Khan, Wasim; Johnstone, David

    2012-01-01

    Anterior Cruciate Ligament (ACL) rupture is a common sporting injury that frequently affects young, athletic patients. Apart from the functional problems of instability, patients with ACL deficient knees also develop osteoarthritis. Although this is frequently cited as an indication for ACL reconstruction, the relationship between ACL rupture, reconstruction and the instigation and progression of articular cartilage degenerative change is controversial.The purpose of this paper is to review the published literature with regards ACL rupture and the multifactorial causes for osteoarthritis progression, and whether or not this is slowed or stopped by ACL reconstruction.There is no evidence in the published literature to support the view that ACL reconstruction prevents osteoarthritis, although it may prevent further meniscal damage. It must be recognised that this conclusion is based on the current literature which has substantial methodological limitations. PMID:22896777

  11. Uveitis (acute anterior)

    PubMed Central

    2010-01-01

    Introduction 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. Methods and outcomes 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). Results 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. Conclusions 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. PMID:21736765

  12. 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

  13. 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. PMID:10537384

  14. [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. PMID:27606653

  15. TRANSVERSE INSTABILITIES IN RHIC.

    SciTech Connect

    Blaskiewicz, M; Cameron, P; Catalan-Lasheras, N; Dawson, C; Degen, C; Drees, K; Fischer, W; Koropsak, E; Michnoff, R; Montag, C; Roser, T

    2003-05-12

    The beam quality in RHIC can be significantly impacted by a transverse instability which can occur just after transition [1]. Data characterizing the instability are presented and analyzed. Techniques for ameliorating the situation are considered.

  16. 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.

  17. Anterior radical debridement and anterior instrumentation in tuberculosis spondylitis.

    PubMed

    Benli, I Teoman; Acaroğlu, Emre; Akalin, Serdar; Kiş, Mahmut; Duman, Evrim; Un, Ahmet

    2003-04-01

    The conventional procedure in the treatment of vertebral tuberculosis is drainage of the abscess, curettage of the devitalized vertebra and application of an antituberculous chemotherapy regimen. Posterior instrumentation results are encouraging in the prevention or treatment of late kyphosis; however, a second-stage operation is needed. Recently, posterolateral or transpedicular drainage without anterior drainage or posterior instrumentation following anterior drainage in the same session has become the preferred treatment, in order that kyphotic deformity can be avoided. Information on the use of anterior instrumentation along with radical debridement and fusion is scarce. This study reports on the surgical results of 63 patients with Pott's disease who underwent anterior radical debridement with anterior fusion and anterior instrumentation (23 patients with Z-plate and 40 patients with CDH system). Average age at the time of operation was 46.8+/-13.4 years. Average duration of follow-up was 50.9+/-12.9 months. Local kyphosis was measured preoperatively, postoperatively and at the last follow-up visit as the angle between the upper and lower end plates of the collapsed vertebrae. Vertebral collapse, destruction, cold abscess, and canal compromise were assessed on magnetic resonance (MR) images. It was observed that the addition of anterior instrumentation increased the rate of correction of the kyphotic deformity (79.7+/-20.1%), and was effective in maintaining it, with an average loss of 1.1 degrees +/-1.7 degrees. Of the 25 patients (39.7%) with neurological symptoms, 20 (80%) had full and 4 (16%) partial recoveries. There were very few intraoperative and postoperative complications (major vessel complication: 3.2%; secondary non-specific infection: 3.2%). Disease reactivation was not seen with the employment of an aggressive chemotherapy regimen. It was concluded that anterior instrumentation is a safe and effective method in the treatment of tuberculosis

  18. Relationship between static anterior laxity using the KT-1000 and dynamic tibial rotation during motion in patients with anatomical anterior cruciate ligament reconstruction.

    PubMed

    Sato, Koji; Maeda, Akira; Takano, Yoshio; Matsuse, Hiroo; Ida, Hirofumi; Shiba, Naoto

    2013-01-01

    The anterior cruciate ligament (ACL) plays an important role in controlling knee joint stability, not only by limiting tibial anterior translation but also by controlling knee axial rotation. The aim of ACL reconstruction is to reduce excessive anterior joint laxity, hoping to restore normal tibiofemoral kinematics including knee axial rotation. The purpose of this study was to investigate the relationship between static anterior instability and tibial rotation during several activities in an anterior cruciate ligament reconstructed knee. Seven patients with unilateral ACL injury performed plain walking, running, landing and side step cutting tasks after ACL reconstruction with a mean follow-up of 14 months. The kinematic data for the 4 motions was measured using a motion analysis system and the point cluster technique. The evaluation period was defined to be from the first contact to removal of the tested leg from the ground. Maximum tibial internal rotation during tasks was calculated using the point cluster technique (PCT). Passive anterior tibial translation was measured using a KT-1000 arthrometer. Regression analysis was used to determine the correlation of the maximum internal rotation with the side-to-side difference of static anterior tibial translation measured using a KT-1000 arthrometer. During side step cutting maneuvers, maximum tibial internal rotation significantly showed negative correlation with static anterior tibial translation (p<0.05, r=0.83). The anterior laxity contributed to the normal knee rotation kinematics. The normal anterior tibial translation obtained by ACL reconstruction is thought to be the key factor in successful restoration of normal knee kinematics. PMID:23925154

  19. 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)

  20. Anterior Repair with Processed Dermis

    MedlinePlus Videos and Cool Tools

    Anterior Repair with Axis® Tutoplast® Processed Dermis and Digitex® - Performed by Dr. Manish Patel Click Here to view the BroadcastMed, Inc. Privacy Policy and Legal Notice © 2016 BroadcastMed, Inc. ...

  1. Anterior approaches for cervical spondylotic myelopathy: which? When? How?

    PubMed

    Emery, Sanford E

    2015-04-01

    Cervical spondylotic myelopathy is a degenerative disorder with an unfavorable natural history. Surgical treatment options have evolved substantially over time, with both anterior and posterior methods proving successful for certain patients with specific characteristics. Anterior decompression of the spinal canal plus fusion techniques for stabilization has several advantages and some disadvantages when compared to posterior options. Understanding the pros and cons of the approaches and techniques is critical for the surgeon to select the best operative treatment strategy for any given patient to achieve the best outcome. Multiple decision-making factors are involved, such as sagittal alignment, number of levels, shape of the pathoanatomy, age and comorbidities, instability, and pre-operative pain levels. Any or all of these factors may be relevant for a given patient, and to varying degrees of importance. Choice of operative approach will therefore be dependent on patient presentation, risks of that approach for a given patient, and to some degree surgeon experience. PMID:25652554

  2. Anterior Cruciate Ligament: Structure, Injuries and Regenerative Treatments.

    PubMed

    Negahi Shirazi, Ali; Chrzanowski, Wojciech; Khademhosseini, Ali; Dehghani, Fariba

    2015-01-01

    Anterior cruciate ligament (ACL) is one of the most vulnerable ligaments of the knee. ACL impairment results in episodic instability, chondral and meniscal injury and early osteoarthritis. The poor self-healing capacity of ACL makes surgical treatment inevitable. Current ACL reconstructions include a substitution of torn ACL via biological grafts such as autograft, allograft. This review provides an insight of ACL structure, orientation and properties followed by comparing the performance of various constructs that have been used for ACL replacement. New approaches, undertaken to induce ACL regeneration and fabricate biomimetic scaffolds, are also discussed. PMID:26545750

  3. Joint instability and osteoarthritis.

    PubMed

    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

  4. 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

  5. [Increase in surgical treatment of anterior cruciate ligament injury].

    PubMed

    Meuffels, D E

    2009-01-01

    An anterior cruciate ligament (ACL) rupture is a very common musculoskeletal injury. The number of ACL reconstructions is increasing, both in the Netherlands and worldwide. Substantial progress has been made in surgical technique: from open to arthroscopic procedures. An ACL reconstruction will not diminish the chance of osteoarthritis, and the biomechanical properties of the knee will never be the same as before the trauma. An ACL reconstruction does, however, reduce the chance of instability, or 'giving way', which is the most important indication for surgical intervention. There are insufficient long-term results described in the literature to indicate either surgery or conservative measures as the treatment of choice. Treatment should be individually determined, taking into consideration factors such as: pattern of symptoms, degree of instability, desire to practise sport, age and willingness to commit to a 9-month rehabilitation programme. PMID:21401972

  6. 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.

  7. Nonlocal magnetorotational instability

    SciTech Connect

    Mikhailovskii, A. B.; Erokhin, N. N.; Lominadze, J. G.; Galvao, R. M. O.; Churikov, A. P.; Kharshiladze, O. A.; Amador, C. H. S.

    2008-05-15

    An analytical theory of the nonlocal magnetorotational instability (MRI) is developed for the simplest astrophysical plasma model. It is assumed that the rotation frequency profile has a steplike character, so that there are two regions in which it has constant different values, separated by a narrow transition layer. The surface wave approach is employed to investigate the MRI in this configuration. It is shown that the main regularities of the nonlocal MRI are similar to those of the local instability and that driving the nonaxisymmetric MRI is less effective than the axisymmetric one, also for the case of the nonlocal instability. The existence of nonlocal instabilities in nonmagnetized plasma is predicted.

  8. Anterior Orbit and Adnexal Amyloidosis

    PubMed Central

    Al Hussain, Hailah; Edward, Deepak P.

    2013-01-01

    Purpose: To describe six cases of anterior orbital and adnexal amyloidosis and to report on proteomic analysis to characterize the nature of amyloid in archived biopsies in two cases. Materials and Methods: The clinical features, radiological findings, pathology, and outcome of six patients with anterior orbit and adnexal amyloidosis were retrieved from the medical records. The biochemical nature of the amyloid was determined using liquid chromatography/mass spectroscopy archived paraffin-embedded tissue in two cases. Results: Of the six cases, three had unilateral localized anterior orbit and lacrimal gland involvement. Four of the six patients were female with an average duration of 12.8 years from the time of onset to presentation eyelid infiltration by amyloid caused ptosis in five cases. CT scan in patients with lacrimal gland involvement (n = 3) demonstrated calcified deformable anterior orbital masses and on pathological exmaintionamyloid and calcific deposits replaced the lacrimal gland acini. Ptosis repair was performed in three patients with good outcomes. One patient required repeated debulking of the mass and one patient had recurrenct disease. Proteomic analysis revealed polyclonal IgG-associated amyloid deposition in one patient and AL kappa amyloid in the second patient. Conclusion: Amyloidosis of the anterior orbit and lacrimal gland can present with a wide spectrum of findings with good outcomes after surgical excision. The nature of amyloid material can be precisely determined in archival pathology blocks using diagnostic proteomic analysis. PMID:24014979

  9. GLENOHUMERAL INSTABILITY AND GLENOID BONE LOSS IN A THROWING ATHLETE

    PubMed Central

    Mair, Scott; Lattermann, Christian

    2013-01-01

    This case presents the challenges of management associated with a young throwing athlete presenting with a history of bilateral anterior shoulder instability. This athlete had multiple surgical interventions over a three‐year period. The imaging modalities provided partial elucidation (at best) of the true picture of the pathology. This case report outlines the decision making process utilized to provide individualized care to a young throwing athlete with bilateral glenohumeral joint instability, recurrent dislocations, and resultant glenoid bone loss. Level of Evidence: 5 (Single Case report) PMID:23593558

  10. Late Anterior Dislocation Due to Posterior Pelvic Tilt in Total Hip Arthroplasty

    PubMed Central

    Kobayashi, Hiroki; Nakashima, Yasuharu; Yamamoto, Takuaki; Motomura, Goro; Kanazawa, Masayuki; Takagishi, Kenji; Iwamoto, Yukihide

    2016-01-01

    Background: Excessive pelvic tilt may be one of the factors leading to instability in total hip arthroplasty (THA), even when the acetabular cup is placed properly. To our knowledge, only a few studies have described late anterior dislocation due to posterior pelvic tilt. We present 3 cases with late anterior dislocations possibly due to posterior pelvic tilt. Cases Presentations: Case-1: An 84-years-old woman fell and presented with an anterior dislocation 12-years after THA. Her pelvis had tilted to approximately 30° posteriorly in a supine position. After conservative treatment, she presented with 10 recurrent anterior dislocations. She had thoracolumbar kyphosis due to multiple compression fractures. Revision with anterior placement of an elevated liner and a 32-mm head corrected the dislocation, and no further dislocations occurred. Case-2: A 78-years-old woman fell and presented with an anterior dislocation 4-years after THA. Her posterior pelvic tilt had increased 23° due to a lumbar compression fracture. Revision by decreasing the cup anteversion was performed, but recurrent posterior dislocations occurred. Owing to her worsened general condition, further treatment was abandoned. Case-3: A 79-years-old woman twisted her body and presented an anterior dislocation 3-years after THA. After manual reduction and conservative treatment, the dislocation recurred. Her posterior pelvic tilt had increased 16°. Conclusion: Although minor trauma triggered the anterior instability in these patients, the underlying pathomechanism existed in the progressive pelvic posterior tilt due to thoracolumbar kyphosis. As longer life expectancy as well as implant survivorship is predicted, attention must be paid to the change of pelvic tilt in elderly patients. PMID:27398108

  11. [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. PMID:17970561

  12. Approaching the ruptured anterior cruciate ligament.

    PubMed

    Sarraf, Khaled M; Sadri, Amir; Thevendran, Gowreeson; Vedi, Vikas

    2011-08-01

    Anterior cruciate ligament (ACL) disruptions are common injuries that currently hold a fearsome reputation among athletes of all abilities and disciplines. Indeed, if the diagnosis is missed at first presentation, it is difficult to attribute ongoing instability and recurrent injury to an ACL tear. Classically, patients then often improve shortly before repeatedly reinjuring their knee. At some point, the knee may lock, necessitating an arthroscopic meniscectomy. Tragically, this then hastens the progression of joint arthrosis and the decline of the joint function. While the burden of responsibility does not lie solely with the junior doctor or the general practitioner, it is often at the first consultation that the natural history of this devastating injury is decided. The ability to recognise, institute early management and reassure patients with ACL tears about the future is an invaluable asset to the non-specialist junior doctor. Once diagnosed, the responsibility of advising and further counselling of patients with ACL injuries is best left to the orthopaedic knee specialist. Family practitioners and emergency room doctors should not feel pressured to offer advice on specialist areas such as return to sports without reconstruction or indeed the need for reconstruction. Indeed, decisions to return to sports with ACL-deficient knees have all too often led to disastrous reinjury events to the articular cartilage and/or the menisci. PMID:21097944

  13. 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

  14. Shoulder Instability in the Overhead Athlete

    PubMed Central

    Nassiri, Nima; Eliasberg, Claire; Jones, Kristofer J.; McAllister, David R.; Petrigliano, Frank A.

    2015-01-01

    Objectives: Overhead athletes place extraordinary physiologic demands on the shoulder during athletic activity. Repetitive microtrauma can result in attenuation of important capsuloligamentous structures that are responsible for providing glenohumeral stability resulting in symptomatic instability. Surgical management can utilize either an arthroscopic or open approach to shoulder stabilization; however, there is a paucity of data to support a specific technique and guide surgical decision making in this unique patient population. The purpose of the present study was to determine functional outcomes, including return to play, range of motion (ROM), validated outcome scores and recurrent instability following arthroscopic and open shoulder stabilization in overhead athletes diagnosed with anterior instability. Methods: MEDLINE and the Cochrane Database of Systematic Reviews were searched. Eleven articles matched our selection criteria for randomized controlled trials in which a cohort of overhead athletes participating in sports including baseball, tennis, volleyball, and freestyle swimming, were surgically treated by capsular plication or Bankart repair through either an open or arthroscopic approach for anterior shoulder subluxation or dislocation. The studies were assessed for methodological quality and relevant data was extracted and further evaluated. Results of comparable groups of trials were pooled and mean differences as well as 95% confidence intervals were calculated for continuous outcomes. A grading schema was designed to assess return to play: return to the same level of play (Grade 1), diminished level of play (Grade 2), and failure to return to play (Grade 3). Results: In overhead athletes with anterior glenohumeral subluxation or dislocation, return to play was similar between arthroscopic and open approaches (Grade 1 = arthroscopic 72 ± 22.6%, open 68.7 ± 7.8%; Grade 2 = arthroscopic 24.2 ± 18.3%, open 34.5 ± 7.8%; Grade 3 = arthroscopic 7.2

  15. A Case of Nonunion Avulsion Fracture of the Anterior Tibial Eminence

    PubMed Central

    Atsumi, Satoru; Arai, Yuji; Nakagawa, Shuji; Inoue, Hiroaki; Ikoma, Kazuya; Fujiwara, Hiroyoshi; Kubo, Toshikazu

    2016-01-01

    Avulsion fracture of the anterior tibial eminence is an uncommon injury. If bone union does not occur, knee extension will be limited by impingement of the avulsed fragment and knee instability will be induced by dysfunction of the anterior cruciate ligament (ACL). This report describes a 55-year-old woman who experienced an avulsion fracture of the right anterior tibial eminence during recreational skiing. Sixteen months later, she presented at our hospital with limitation of right knee extension. Plain radiography showed nonunion of the avulsion fracture region, and arthroscopy showed that the avulsed fragment impinged the femoral intercondylar notch during knee extension. The anterior region of the bony fragment was debrided arthroscopically until the knee could be extended completely. There was no subsequent instability, and the patient was able to climb a mountain 6 months after surgery. These findings indicate that arthroscopic debridement of an avulsed fragment for nonunion of an avulsion fracture of the anterior tibial eminence is a minimally invasive and effective treatment for middle-aged and elderly patients with a low level of sports activity. PMID:27119035

  16. The anterior talofibular ligament: A detailed morphological study.

    PubMed

    Khawaji, Bader; Soames, Roger

    2015-09-01

    The anterior talofibular ligament (ATFL) is commonly injured and may result in ankle instability. Good results from ATFL reconstruction have been reported; however complications and movement restrictions have also been observed. ATFL differences have been reported; however details of its precise bony attachment are lacking. This study provides a detailed morphology of the ATFL with respect to surgical and clinical applications. ATFL morphology, number of bands and the exact insertion points were studied in 50 formaldehyde embalmed feet. ATFL length was measured in different joint positions to assess its functional role: ATFL length varied from 18.81 mm in dorsiflexion to 21.06 mm in plantarflexion: mid-length width and thickness were 4.97 mm and 1.01 mm respectively. The bony attachment lengths were also measured: mean proximal and distal bony attachment lengths were 4.68 mm and 3.1mm respectively, while 13.04 mm had no bony attachment. One (22.9%), two (56.3%) and three (20.8%) band morphologies were observed originating 10.37 mm anterosuperior to the lateral malleolar tip and inserting 3.92 mm anterior to the anterior lateral malleolar line (ALML). Detailed morphology of the ATFL may help in restoring injured ATFL function by appropriate ligament reconstruction, as well as aid the understanding of the mechanism of ligament injury. PMID:26205996

  17. 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

  18. Chiral plasma instabilities.

    PubMed

    Akamatsu, Yukinao; Yamamoto, Naoki

    2013-08-01

    We study the collective modes in relativistic electromagnetic or quark-gluon plasmas with an asymmetry between left- and right-handed chiral fermions, based on the recently formulated kinetic theory with Berry curvature corrections. We find that there exists an unstable mode, signaling the presence of a plasma instability. We argue the fate of this "chiral plasma instability" including the effect of collisions, and briefly discuss its relevance in heavy ion collisions and compact stars. PMID:23952387

  19. 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.

  20. Anterior spinal cord syndrome of unknown etiology

    PubMed Central

    Klakeel, Merrine; Thompson, Justin; McDonald, Frank

    2015-01-01

    A spinal cord injury encompasses a physical insult to the spinal cord. In the case of anterior spinal cord syndrome, the insult is a vascular lesion at the anterior spinal artery. We present the cases of two 13-year-old boys with anterior spinal cord syndrome, along with a review of the anatomy and vasculature of the spinal cord and an explanation of how a lesion in the cord corresponds to anterior spinal cord syndrome. PMID:25552812

  1. Cervical ligamentous instability in a canine in vivo model.

    PubMed

    Whitehill, R; Moran, D J; Fechner, R E; Ruch, W W; Drucker, S; Hooper, W E; McCoig, J A

    1987-12-01

    A canine in vivo model of midcervical ligamentous instability was developed by dividing the anterior longitudinal ligament, anulus fibrosus, and all posterior ligamentous structures including the ligamentum flavum. The natural history of healing in the model, the effect on its healing by an adjacent one-level arthrodesis, and the effect of a one-level arthrodesis on normal adjacent ligamentous structures were studied radiographically, mechanically, and histologically. The authors determined that healing takes place primarily by anterior scar formation in their instability model but not to a degree sufficient to recreate normal mechanical stability. After three months, healing in the model was not affected by an adjacent arthrodesis; however, acutely, instability apparently was increased as three animals became quadriplegic between the second and fourth postoperative days. Arthrodesis did not affect adjacent normal ligamentous structures, during this period. Incomplete healing in the authors' model supports those who advocate arthrodesis as the treatment of choice for destabilizing cervical ligamentous injury. The authors previously reported the case of a patient who sustained bilateral facet dislocations adjacent to an arthrodesed segment and questioned whether this resulted from a stress-concentrating effect. This study indicates that this could well have been the case acutely. Thus, inadvertent exclusion of an unstable segment from an arthrodesis has potentially catastrophic results. Finally, the authors also have previously questioned whether arthrodesis of a midcervical segment could lead to instability of adjacent normal segments. This project does not support such a concern, at least for the three postoperative months of study. PMID:3441821

  2. 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.

  3. 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...

  4. Results of meniscectomy and meniscal repair in anterior cruciate ligament reconstruction

    PubMed Central

    DELEDDA, DAVIDE; ROSSO, FEDERICA; COTTINO, UMBERTO; BONASIA, DAVIDE EDOARDO; ROSSI, ROBERTO

    2015-01-01

    Meniscal tears are commonly associated with anterior cruciate ligament (ACL) injuries. A deficient medial meniscus results in knee instability and could lead to higher stress forces on the ACL reconstruction. Comparison of results in meniscectomy and meniscal repairs revealed worse clinical outcomes in meniscectomy, but higher re-operation rates in meniscal repairs. Our aim was to review the results of ACL reconstruction associated with meniscectomy or meniscal repair. PMID:26889472

  5. Traumatic anterior cervical pseudomeningocele causing intracranial hypotension successfully treated with blood patch: case report.

    PubMed

    Takahashi, Edwin A; Eckel, Laurence J; Diehn, Felix E; Schwartz, Kara M; Hunt, Christopher H; Daniels, David J

    2015-09-01

    Cervical pseudomeningocele is a rare complication of trauma. It develops when an extradural collection of cerebrospinal fluid (CSF) develops after a dural breach. The authors present the unusual case of a 33-year-old man with progressive headache, neck pain, mental status changes, and cardiopulmonary instability after polytrauma sustained from a motorcycle-versus-deer collision, without improvement during a 5-day hospitalization. Magnetic resonance imaging revealed a collection of CSF anterior to the cervical thecal sac compatible with an anterior cervical pseudomeningocele. A nontargeted epidural blood patch was performed with subsequent resolution of the patient's symptoms. Anterior cervical pseudomeningoceles are usually asymptomatic; however, these lesions can cause orthostatic headaches, neck pain, and cardiopulmonary compromise, as it did in the featured patient. Pseudomeningoceles should be included in the differential diagnosis for posttrauma patients with progressive neurological decline or postural headache, and blood patch may be an effective minimally invasive treatment. PMID:26023899

  6. The spinal nail: a new implant for short-segment anterior instrumentation of the thoracolumbar spine.

    PubMed

    Dawson, J M; DeBoer, D K; Spengler, D M; Schwartz, H S

    1996-08-01

    The biomechanics of a new spinal implant were evaluated and its dependence on an anterior strut graft was determined. Six fresh-frozen adult porcine spines were used. An L3 corpectomy was created. The spinal nail was inserted intraosseously into the middle column of the L2-L4 vertebral bodies in a trough. Implant drill holes were made for proximal and distal locking bolts in L2 and L4. A locking plate bridged the L2 and L4 trough and anchored the exposed ends of the locking bolts. Testing was performed in axial compression, torsion, and flexion. The axial and torsional stability of the spine instrumented with the spinal nail are similar to results with other devices when used with anterior strut grafting. The axial and flexural stiffnesses of the instrumented spine are independent of strut grafting. This study suggests that this device may be useful for reconstruction of the anterior spine because of instability. PMID:8877956

  7. 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. PMID:25661070

  8. Electrokinetic instability in microchannels

    NASA Astrophysics Data System (ADS)

    Schiffbauer, Jarrod; Demekhin, Evgeny A.; Ganchenko, Georgy

    2012-05-01

    The effect of geometric confinement on electroconvective instability due to nonequilibrium electro-osmotic slip at the interface of an electrolytic fluid and charge-selective solid is studied. It is shown that the topology of the marginal stability curves and the behavior of the critical parameters depend strongly on both channel geometry and dimensionless Debye length at low voltages for sufficiently deep channels, corresponding to the Rubinstein-Zaltzman instability mechanism, but that stability is governed almost entirely by channel depth for narrow channels at higher voltages. For shallow channels, it is shown that above a transition threshold, determined by both channel depth and Debye length, the low-voltage instability is completely suppressed.

  9. Ringed Accretion Disks: Instabilities

    NASA Astrophysics Data System (ADS)

    Pugliese, D.; Stuchlík, Z.

    2016-04-01

    We analyze the possibility that several instability points may be formed, due to the Paczyński mechanism of violation of mechanical equilibrium, in the orbiting matter around a supermassive Kerr black hole. We consider a recently proposed model of a ringed accretion disk, made up by several tori (rings) that can be corotating or counter-rotating relative to the Kerr attractor due to the history of the accretion process. Each torus is governed by the general relativistic hydrodynamic Boyer condition of equilibrium configurations of rotating perfect fluids. We prove that the number of the instability points is generally limited and depends on the dimensionless spin of the rotating attractor.

  10. 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.

  11. Varus Posteromedial Instability.

    PubMed

    Ramirez, Miguel A; Stein, Jason A; Murthi, Anand M

    2015-11-01

    Varus posteromedial instability of the elbow is a result of traumatic injury to the medial facet of the coronoid and usually the lateral collateral ligament. Treatment of these fractures is usually surgical; poor outcomes have been described with nonoperative treatment. Surgical management consists of coronoid fracture fixation with plates, screws, or sutures and radial collateral ligament repair. Outcomes of these injuries are mixed, but most series report fair to good objective scores. The purpose of this article is to describe the pathophysiology of varus posteromedial instability, discuss the management of this injury, and report the outcomes of treatment. PMID:26498545

  12. [Chronic instability of the pubic symphysis : Etiology, diagnostics and treatment management].

    PubMed

    Herren, C; Dienstknecht, T; Siewe, J; Kobbe, P; Pape, H C; Hildebrand, F

    2016-05-01

    The most frequent causes of chronic instability of the pubic symphysis are sports-related continual overload and traumatic symphyseal injuries. Acute injury of the pubic symphysis may be the result of external forces acting on the anterior pelvic ring or the result of internal forces, such as those arising during parturition. The postpartum form of instability following a complication-free birth is reversible and usually returns to normal within a few months through strengthening of the pelvic floor muscles. Residual instability of the pubis symphysis is on the whole a rare complication. Although established therapy options for acute symphyseal separation can be found in the literature, there are only a few case reports on chronic symphyseal instability. There are no guidelines on standardized therapy options. This review article examines the etiology, clinical findings, diagnostic techniques and management options for patients suffering from chronic symphyseal instability. PMID:27146805

  13. Conservative management of idiopathic anterior atlantoaxial subluxation without neurological deficits in an 83-year-old female: A case report

    PubMed Central

    Marchand, Andrée-Anne; Wong, Jessica J.

    2014-01-01

    Atlantoaxial subluxation that is not related to traumatic, congenital, or rheumatological conditions is rare and can be a diagnostic challenge. This case report details a case of anterior atlantoaxial subluxation in an 83-year-old female without history of trauma, congenital, or rheumatological conditions. She presented to the chiropractor with insidious neck pain and headaches, without neurological deficits. Radiographs revealed a widened atlantodental space (measuring 6 mm) indicating anterior atlantoaxial subluxation and potential sagittal atlantoaxial instability. Prompt detection and appropriate conservative management resulted in favourable long-term outcome at 13-months follow-up. Conservative management included education, mobilizations, soft tissue therapy, monitoring for neurological progression, and co-management with the family physician. The purpose of this case report is to heighten awareness of the clinical presentation of idiopathic anterior atlantoaxial subluxation without neurological deficits. Discussion will focus on the incidence, mechanism, clinical presentation, and conservative management of a complex case of anterior atlantoaxial subluxation. PMID:24587500

  14. Stereopsis after anterior temporal lobectomy.

    PubMed

    Verhoef, Bram-Ernst; Decramer, Thomas; van Loon, Johannes; Goffin, Jan; Van Paesschen, Wim; Janssen, Peter; Theys, Tom

    2016-09-01

    Brain areas critical for stereopsis have been investigated in non-human primates but are largely unknown in the human brain. Microelectrode recordings and functional MRI (fMRI) studies in monkeys have shown that in monkeys the inferior temporal cortex is critically involved in 3D shape categorization. Furthermore, some human fMRI studies similarly suggest an involvement of visual areas in the temporal lobe in depth perception. We aimed to investigate the role of the human anterior temporal neocortex in stereopsis by assessing stereoscopic depth perception before and after anterior temporal lobectomy. Eighteen epilepsy surgery patients were tested, pre- and postoperatively, in 3 different depth discrimination tasks. Sensitivity for local and global disparity was tested in a near-far discrimination task and sensitivity for 3D curvature was assessed in a convex-concave discrimination task, where 3D shapes were presented at different positions in depth. We found no evidence that temporal lobe epilepsy surgery has a significant effect on stereopsis. In contrast with earlier findings, we conclude that local as well as global stereopsis is maintained after unilateral resection of the temporal pole in epilepsy surgery patients. Our findings, together with previous studies, suggest that in humans more posterior visual regions underlie depth perception. PMID:27344239

  15. INSTABILITIES IN THE SNS.

    SciTech Connect

    BLASKIEWICZ,M.

    1999-03-29

    The 2MW Spallation Neutron Source (SNS) will have a D.C. beam current of 40 A at extraction, making it one of the worlds most intense accelerators. Coherent instabilities are a major concern and efforts to predict beam behavior are described.

  16. Two-fluid instability

    SciTech Connect

    Stewart, H.B.

    1984-01-01

    The ability of interpenetrating flow models to represent multidimensional instabilities is probed by numerical experiments with an L-shaped two-fluid jet. Periodic and nonperiodic oscillations of various types are observed, and a partial phase portrait is constructed. The numerical experiments suggest new approaches to verifying transient interpenetrating flow models. 18 references.

  17. Electrostatic heat flux instabilities

    NASA Technical Reports Server (NTRS)

    Morrison, P. J.; Ionson, J. A.

    1980-01-01

    The electrostatic cyclotron and ion acoustic instabilities in a plasma driven by a combined heat flux and current were investigated. The minimum critical heat conduction speed (above which the plasma is unstable) is given as a function of the ratio of electron to ion temperatures.

  18. Global Linear Instability

    NASA Astrophysics Data System (ADS)

    Theofilis, Vassilios

    2011-01-01

    This article reviews linear instability analysis of flows over or through complex two-dimensional (2D) and 3D geometries. In the three decades since it first appeared in the literature, global instability analysis, based on the solution of the multidimensional eigenvalue and/or initial value problem, is continuously broadening both in scope and in depth. To date it has dealt successfully with a wide range of applications arising in aerospace engineering, physiological flows, food processing, and nuclear-reactor safety. In recent years, nonmodal analysis has complemented the more traditional modal approach and increased knowledge of flow instability physics. Recent highlights delivered by the application of either modal or nonmodal global analysis are briefly discussed. A conscious effort is made to demystify both the tools currently utilized and the jargon employed to describe them, demonstrating the simplicity of the analysis. Hopefully this will provide new impulses for the creation of next-generation algorithms capable of coping with the main open research areas in which step-change progress can be expected by the application of the theory: instability analysis of fully inhomogeneous, 3D flows and control thereof.

  19. Effects of increased anterior-posterior voluntary sway frequency on mechanical and perceived postural stability.

    PubMed

    Martin Lorenzo, Teresa; Vanrenterghem, Jos

    2015-02-01

    Despite a substantial number of studies, the interaction between mechanical indicators of stability and perception of instability remains unclear. The purpose of this study was to determine the effect of sway frequency and verbal restraint on mechanical and perceived postural stability. Fourteen participants underwent a series of standing voluntary anterior-posterior swaying trials at three frequencies (20, 40, and 60bpm) and two levels of restraint (non restraint and verbally restraint to swaying at the ankle). Repeated measures ANOVA tests revealed greater mechanical stability defined though the margin of stability, and greater horizontal ground reaction forces, while the center of pressure excursions remained unchanged with increasing frequency. Furthermore, ground reaction forces were greater in the non-restraint condition. Moreover, a tendency toward greater perceived instability with increasing voluntary sway frequency was observed. Our results indicate that variations in sway frequency and verbal restraint resulted in noticeable alterations in mechanical indicators of stability, with no clear effect on perceived instability. PMID:25498287

  20. Combined anterolateral ligament and anatomic anterior cruciate ligament reconstruction of the knee.

    PubMed

    Smith, James O; Yasen, Sam K; Lord, Breck; Wilson, Adrian J

    2015-11-01

    Although anatomic anterior cruciate ligament (ACL) reconstruction is established for the surgical treatment of anterolateral knee instability, there remains a significant cohort of patients who continue to experience post-operative instability. Recent advances in our understanding of the anatomic, biomechanical and radiological characteristics of the native anterolateral ligament (ALL) of the knee have led to a resurgent interest in reconstruction of this structure as part of the management of knee instability. This technical note describes our readily reproducible combined minimally invasive technique to reconstruct both the ACL and ALL anatomically using autologous semitendinosus and gracilis grafts. This method of ALL reconstruction can be easily integrated with all-inside ACL reconstruction, requiring minimal additional operative time, equipment and expertise. Level of evidence V. PMID:26387120

  1. Rotational laxity after anterior cruciate ligament injury by kinematic evaluation of clinical tests.

    PubMed

    Zaffagnini, S; Martelli, S; Falcioni, B; Motta, M; Marcacci, M

    2000-01-01

    Despite the numerous studies on anterior cruciate ligament biomechanics and clinical tests, some disagreements still exist in the literature on the role of ACL in restraining rotations and which kinematic test after ACL injuries is the most suitable to evaluate this instability. This work analyses the capability of passive clinical and stress tests to detect an ACL state quantifying rotational instability. The study was conducted on animal knees with a new protocol. We found that an internal-external stress test can give a useful indication on the ACL state when used to estimate the side to side differences while varus-valgus laxity and secondary motions in standard kinematic tests did not seem to be affected by ACL injury. The kinematic protocol performed could be used intra-operatively to quantify rotations, allowing a more accurate evaluation of knee instability to guide surgical reconstruction and improve its final outcome. PMID:11204247

  2. Locally aggressive aneurysmal bone cyst of C4 vertebra treated by total en bloc excision and anterior plus posterior cervical instrumentation

    PubMed Central

    Parmar, Himanshu N.; Agrawal, Vinod A.; Shah, Munjal S.; Nanda, Saurav N.

    2015-01-01

    We are presenting a case of cervical (C4) aneurysmal bone cyst in a 13-year-old girl, came to the outpatient department with neck pain and stiffness since 6 months and normal neurology. We did an en bloc excision of locally aggressive tumor through anterior plus posterior approach and stabilization by lateral mass screw fixation and anterior cervical instrumentation. Involvement of several adjacent cervical vertebrae by an aneurysmal bone cyst is rare, and conventional treatment with curettage and bone grafting is most likely to carry a high rate of recurrence and spinal instability. We recommend complete excision of the tumor and instrumentation in a single stage to avoid instability. PMID:26288549

  3. Tracking Code for Microwave Instability

    SciTech Connect

    Heifets, S.; /SLAC

    2006-09-21

    To study microwave instability the tracking code is developed. For bench marking, results are compared with Oide-Yokoya results [1] for broad-band Q = 1 impedance. Results hint to two possible mechanisms determining the threshold of instability.

  4. Association Between Serum Relaxin and Subsequent Shoulder Instability.

    PubMed

    Owens, Brett D; Cameron, Kenneth L; Clifton, Kari B; Svoboda, Steven J; Wolf, Jennifer Moriatis

    2016-07-01

    Ligamentous laxity correlates with shoulder instability. Relaxin is a hormone that has been linked to laxity in the knee and has been shown to be a risk factor for anterior cruciate ligament (ACL) injury. This study prospectively evaluated the association between relaxin and acute shoulder instability. A prospective cohort study of 1050 young athletes was performed between 2006 and 2010. The authors conducted a nested case-control analysis within this cohort to evaluate the association between preinjury serum relaxin concentration and the likelihood of subsequent shoulder instability. The study compared 53 patients who had shoulder instability and 53 control subjects who were matched for sex, age, height, and weight. The serum relaxin concentration in preinjury baseline samples was tested with enzyme-linked immunosorbent assay analysis in duplicate. Independent t tests were performed to identify differences in mean serum relaxin concentration between patients with shoulder instability and uninjured control subjects. Logistic regression was used to evaluate whether preinjury baseline serum relaxin concentration was associated with the subsequent likelihood of shoulder instability. Of the 53 patients with instability, 13 (25%) had a detectable serum relaxin concentration compared with 9 (17%) of uninjured control subjects (P=.34). Mean serum relaxin concentration in the injury group was 3.69±1.78 pg/mL and 2.20±0.97 pg/mL in uninjured control subjects (P=.02). Increased serum relaxin concentration was associated with the subsequent likelihood of acute shoulder instability. Subjects were 2.18 times (odds ratio, 2.18; 95% confidence interval, 1.01-4.76) more likely to have acute shoulder instability during the follow-up period for every 1-pg/mL increase in serum relaxin concentration at baseline. The findings suggest that serum relaxin concentration is associated with a risk of subsequent shoulder instability in young athletes. Further research on the role of relaxin

  5. 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

  6. [Therapy of posterior and posterolateral knee instability].

    PubMed

    Jakob, R P; Rüegsegger, M

    1993-11-01

    The natural course after posterior cruciate ligament (PCL) tear is a slow process of degeneration starting in the medial compartment. Functional disability is mainly present in those instabilities that are combined with posterolateral insufficiency. The surgical treatment at present mainly addresses these combined types of posterior-posterolateral instability. It is generally agreed that suture of the torn PCL alone is insufficient and augmentation with autologous structures, such as the patellar ligament, are mandatory. Synthetic augmentation to facilitate after treatment is another adjunct. Because of the difficulty of precise tibial tunnel placement a two-stage procedure is advocated, an anterior approach with the patient supine being used for femoral graft placement. If a posterior approach with the patient prone is used, a straight posterior incision is made between the two heads of the gastrocnemius and the neuromuscular bundle. With this approach the tibial bone block is placed in a trough. The accuracy of graft placement and the immediate functional aftertreatment facilitated by the use of osseous fixation of a synthetic augmentation device at both ends have made better results of surgical reconstruction of the PCL possible. PMID:8309701

  7. Cervical Cord Decompression Using Extended Anterior Cervical Foraminotomy Technique

    PubMed Central

    Kim, Sung-Duk; Lee, Cheol-Young; Kim, Hyun-Woo; Jung, Chul-Ku; Kim, Jong Hyun

    2014-01-01

    Objective At present, gold-standard technique of cervical cord decompression is surgical decompression and fusion. But, many complications related cervical fusion have been reported. We adopted an extended anterior cervical foraminotomy (EACF) technique to decompress the anterolateral portion of cervical cord and report clinical results and effectiveness of this procedure. Methods Fifty-three patients were operated consecutively using EACF from 2008 to 2013. All of them were operated by a single surgeon via the unilateral approach. Twenty-two patients who exhibited radicular and/or myelopathic symptoms were enrolled in this study. All of them showed cervical cord compression in their preoperative magnetic resonance scan images. Results In surgical outcomes, 14 patients (64%) were classified as excellent and six (27%), as good. The mean difference of cervical cord anterior-posterior diameter after surgery was 0.92 mm (p<0.01) and transverse area was 9.77 mm2 (p<0.01). The dynamic radiological study showed that the average post-operative translation (retrolisthesis) was 0.36 mm and the disc height loss at the operated level was 0.81 mm. The change in the Cobb angle decreased to 3.46, and showed slight kyphosis. The average vertebral body resection rate was 11.47%. No procedure-related complications occurred. Only one patient who had two-level decompression needed anterior fusion at one level as a secondary surgery due to postoperative instability. Conclusions Cervical cord decompression was successfully performed using EACF technique. This procedure will be an alternative surgical option for treating cord compressing lesions. Long-term follow-up and a further study in larger series will be needed. PMID:25328648

  8. Biomechanical benefits of anterior offsetting of humeral head component in posteriorly unstable total shoulder arthroplasty: A cadaveric study.

    PubMed

    Kim, Hyun-Min Mike; Chacon, Alexander C; Andrews, Seth H; Roush, Evan P; Cho, Edward; Conaway, William K; Kunselman, Allen R; Lewis, Gregory S

    2016-04-01

    Restoration of joint stability during total shoulder arthroplasty can be challenging in the face of severe glenoid retroversion. A novel technique of humeral head component anterior-offsetting has been proposed to address posterior instability. We evaluated the biomechanical benefits of this technique in cadaveric specimens. Total shoulder arthroplasty was performed in 14 cadaveric shoulders from 7 donors. Complementary shoulders were assigned to either 10° or 20° glenoid retroversion, with retroversion created by eccentric reaming. Two humeral head component offset positions were tested in each specimen: The anatomic (posterior) and anterior (reverse). With loads applied to the rotator cuff and deltoid, joint contact pressures and the force and energy required for posterior humeral head translation were measured. The force and energy required to displace the humeral head posteriorly increased significantly with the anterior offset position compared to the anatomic offset position. The joint contact pressures were significantly shifted anteriorly, and the joint contact area significantly increased with the anterior offset position. Anterior offsetting of the humeral head component increased the resistance to posterior humeral head translation, shifted joint contact pressures anteriorly, and increased joint contact area, thus, potentially increasing the joint stability in total shoulder arthroplasty with simulated glenoid retroversion. PMID:26356804

  9. Anatomic Anterior Cruciate Ligament Reconstruction

    PubMed Central

    Murawski, Christopher D.; Wolf, Megan R.; Araki, Daisuke; Muller, Bart; Tashman, Scott

    2013-01-01

    Anatomic anterior cruciate ligament (ACL) reconstruction is common procedure performed by orthopedic surgeons, particularly in association with sports-related injuries. Whereas traditional reconstruction techniques used a single bundle graft that was typically placed in a non-anatomic position, a renewed interest in anatomy has facilitated the popularization of anatomic reconstruction techniques. Recently, a focus has been placed on individualizing ACL surgery based on each patient’s native anatomical characteristics (e.g., insertion site size, notch size, and shape), thereby dictating the ultimate procedure of choice. As subjective outcome measurements have demonstrated varying outcomes with respect to single- versus double-bundle ACL reconstruction, investigators have turned to more objective techniques, such as in vivo kinematics, as a means of evaluating joint motion and cartilage contact mechanics. Further investigation in this area may yield important information with regard to the potential progression to osteoarthritis after ACL reconstruction, including factors affecting or preventing it. PMID:26069663

  10. Mucoid degeneration of the anterior cruciate ligament: Management and outcome

    PubMed Central

    Pandey, Vivek; Suman, CPS; Sharma, Swati; Rao, Sripathi P; Kiran Acharya, KV; Sambaji, Charudutt

    2014-01-01

    Background: Mucoid degeneration (MD) is a rare pathological affection of the anterior cruciate ligament (ACL). Mucinous material within the substance of ACL produces pain and limited motion in the knee. This series describes the clinicoradiological presentation of patients with mucoid ACL, partial arthroscopic debridement of ACL and outcomes. Materials and Methods: During a period of 3 years, 11 patients were included based upon the clinical suspicion, magnetic resonance imaging (MRI) findings, arthroscopic features and histopathologic confirmation of MD of ACL. Result: Six patients were male and five were female with median age of 40 years (range 21-59 years). All patients complained of knee pain with median duration of 5 months (range 1-24 months). All patients had painful deep flexion with 63.6% (N = 7) reporting trivial trauma before the onset of symptoms. MRI revealed MD of ACL in all with associated cyst in three patients. Partial debridement of ACL was done in ten and complete in one patient. None of them required notchplasty. Histopathology confirmed the diagnosis in all of them. At the mean followup of 13.81 months (range 6-28 months), all patients regained complete flexion and none complained of instability. Conclusion: Prior knowledge of condition with high index of suspicion and careful interpretation of MRI can establish the diagnosis preoperatively. It responds well to partial debridement of ACL and mucinous material without development of instability. PMID:24741143

  11. 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

  12. Genomic Instability and Cancer

    PubMed Central

    Yao, Yixin; Dai, Wei

    2014-01-01

    Genomic instability is a characteristic of most cancer cells. It is an increased tendency of genome alteration during cell division. Cancer frequently results from damage to multiple genes controlling cell division and tumor suppressors. It is known that genomic integrity is closely monitored by several surveillance mechanisms, DNA damage checkpoint, DNA repair machinery and mitotic checkpoint. A defect in the regulation of any of these mechanisms often results in genomic instability, which predisposes the cell to malignant transformation. Posttranslational modifications of the histone tails are closely associated with regulation of the cell cycle as well as chromatin structure. Nevertheless, DNA methylation status is also related to genomic integrity. We attempt to summarize recent developments in this field and discuss the debate of driving force of tumor initiation and progression. PMID:25541596

  13. 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.}

  14. Beam-beam instability

    SciTech Connect

    Chao, A.W.

    1983-08-01

    The subject of beam-beam instability has been studied since the invention of the colliding beam storage rings. Today, with several colliding beam storage rings in operation, it is not yet fully understood and remains an outstanding problem for the storage ring designers. No doubt that good progress has been made over the years, but what we have at present is still rather primitive. It is perhaps possible to divide the beam-beam subject into two areas: one on luminosity optimization and another on the dynamics of the beam-beam interaction. The former area concerns mostly the design and operational features of a colliding beam storage ring, while the later concentrates on the experimental and theoretical aspects of the beam-beam interaction. Although both areas are of interest, our emphasis is on the second area only. In particular, we are most interested in the various possible mechanisms that cause the beam-beam instability.

  15. Whistler modulational instability.

    NASA Technical Reports Server (NTRS)

    Brinca, A. L.

    1973-01-01

    Derivation of the modulational instability characteristics of whistlers in cold and hot plasmas. The cold-plasma analysis considers both ion motion and relativistic effects; the unstable band, with a growth rate proportional to (B/B sub zero)squared, is contiguous to Omega sub e/4 and, depending on the plasma density, lies above or below that frequency (Omega sub e is the electron cyclotron frequency of the static magnetic field; B and B sub zero are the whistler and static magnetic fields). In hot plasmas, stability occurs between Omega sub e/4 and Omega prime (less than Omega sub e), with Omega prime depending mainly on the mean energy and anisotropy of the energetic electron population; the complementary unstable band has a growth rate proportional to (B/B sub zero) to the 1/2 power. The relevance of the instability to whistlers in the magnetosphere is discussed.

  16. 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.

  17. 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.

  18. 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

  19. 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

  20. 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. PMID:27103865

  1. 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.

  2. Atraumatic Anterior Dislocation of the Hip Joint

    PubMed Central

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

    2015-01-01

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

  3. 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

  4. 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

  5. The contribution of anterior deltoid ligament to ankle stability in isolated lateral malleolar fractures.

    PubMed

    Lee, Tae Hoon; Jang, Kyu Sun; Choi, Gi Won; Jeong, Chan Dong; Hong, Suk Joo; Yoon, Min A; Kim, Hak Jun

    2016-07-01

    The treatment of isolated lateral malleolar fractures with deltoid ligament rupture remains controversial. We prospectively analysed 35 patients with isolated lateral malleolar fractures during 2006-2013. Radiography and magnetic resonance imaging (MRI) were performed to assess the degree of reduction, ligament damage, and stability. Internal fixation was performed for all unstable valgus fractures with unacceptable fracture parameters. Fractures with residual valgus instability after fixation underwent anterior deltoid repair. The mean anterior deltoid ligament grade based on MRI was significantly different between the high-grade unstable group and the stable and low-grade unstable groups (p=0.037 and 0.004, respectively). Postoperative medial clear space measurements were not significantly different between groups. MRI was shown to be a useful tool in the preoperative identification of isolated lateral malleolus fractures prone to valgus instability. In the case of high-grade unstable fractures of the lateral malleolus, repair of the anterior deltoid ligament is adequate for restoring medial stability. PMID:27133289

  6. Anterior Cruciate Ligament Reconstruction Rehabilitation

    PubMed Central

    Wright, Rick W.; Haas, Amanda K.; Anderson, Joy; Calabrese, Gary; Cavanaugh, John; Hewett, Timothy E.; Lorring, Dawn; McKenzie, Christopher; Preston, Emily; Williams, Glenn; Amendola, Annunziato

    2015-01-01

    Context: Anterior cruciate ligament (ACL) reconstruction rehabilitation has evolved over the past 20 years. This evolution has been driven by a variety of level 1 and level 2 studies. Evidence Acquisition: The MOON Group is a collection of orthopaedic surgeons who have developed a prospective longitudinal cohort of the ACL reconstruction patients. To standardize the management of these patients, we developed, in conjunction with our physical therapy committee, an evidence-based rehabilitation guideline. Study Design: Clinical review. Level of Evidence: Level 2. Results: This review was based on 2 systematic reviews of level 1 and level 2 studies. Recently, the guideline was updated by a new review. Continuous passive motion did not improve ultimate motion. Early weightbearing decreases patellofemoral pain. Postoperative rehabilitative bracing did not improve swelling, pain range of motion, or safety. Open chain quadriceps activity can begin at 6 weeks. Conclusion: High-level evidence exists to determine appropriate ACL rehabilitation guidelines. Utilizing this protocol follows the best available evidence. PMID:26131301

  7. Validity and reliability of the SPORTS score for shoulder instability

    PubMed Central

    BLONNA, DAVIDE; BELLATO, ENRICO; CARANZANO, FRANCESCO; BONASIA, DAVIDE E.; MARMOTTI, ANTONGIULIO; ROSSI, ROBERTO; CASTOLDI, FILIPPO

    2014-01-01

    Purpose athletes affected by shoulder instability cannot be judged solely according to the criteria used for non-athletes. In order to improve the assessment of shoulder instability surgery outcomes, the SPORTS score was tested in a cohort of athletes. Methods ninety-eight athletes at an average follow-up of 4.6 years (range 1–9.2) after open or arthroscopic surgery for recurrent anterior shoulder instability were included in this study. The patients were asked to complete the SPORTS score questionnaire twice, with an interval of 2–3 weeks between the two assessments. The Bland-Altman method and the intra-class correlation coefficient were used to measure reliability. Criterion validity was assessed by calculating the Spearman correlation coefficient between the SPORTS score and the Western Ontario Shoulder Instability Index (WOSI) score, the Rowe score, the Oxford Shoulder Instability Score (OSIS), and the Subjective Shoulder Value (SSV). Results the SPORTS score showed excellent test-retest reliability. The systematic error between the first and the second assessment was 0.3 points (95% upper limit of agreement = 2.3 points). The criterion validity was found to be strong for the SPORTS score, which correlated best with the SSV and the “sport, recreation, and work” component of the WOSI score. The SPORTS score had an acceptable floor effect (8%). The ceiling effect was 46%, which was better than the ceiling effects seen with the Rowe, OSIS and WOSI scores. Conclusions this study suggests that the SPORTS score is a valid score in the assessment of athletes after surgery for shoulder instability and that it adds important information to the currently available scores. Level of evidence Level III, diagnostic study of nonconsecutive patients. PMID:25606544

  8. 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

  9. Discoid lateral meniscus: prevalence of peripheral rim instability.

    PubMed

    Klingele, Kevin E; Kocher, Mininder S; Hresko, M Timothy; Gerbino, Peter; Micheli, Lyle J

    2004-01-01

    The purpose of this study was to determine the prevalence of peripheral rim instability in discoid lateral meniscus. A consecutive series of 112 patients (128 knees) (mean age 10.0 years [range 1 month to 22 years]) who underwent arthroscopic evaluation and treatment of a discoid lateral meniscus between 1993 and 2001 was reviewed. Of those discoid menisci classified intraoperatively (n = 87), 62.1% (n = 54) were complete discoid lateral menisci and 37.9% (n = 33) were incomplete discoid lateral menisci. An associated meniscal tear was present in 69.5% (n = 89) of all knees studied. Overall, 28.1% (n = 36) of discoid lateral menisci had peripheral rim instability: 47.2% (n = 17) were unstable at the anterior-third peripheral attachment, 11.1% (n = 4) at the middle-third peripheral attachment, and 38.9% (n = 14) at the posterior-third peripheral attachment. Thirty-one of the 36 unstable discoid menisci underwent repair of the peripheral meniscal rim attachment. One patient underwent a complete, open meniscectomy. Peripheral rim instability was significantly more common in complete discoid lateral menisci (38.9% vs. 18.2%; P = 0.043) and in younger patients (8.2 vs. 10.7 years; P = 0.002). The frequency of peripheral instability mandates a thorough assessment of meniscal stability at all peripheral attachments during the arthroscopic evaluation and treatment of discoid lateral meniscus, particularly in complete variants and in younger children. PMID:14676539

  10. Genome instability and aging.

    PubMed

    Vijg, Jan; Suh, Yousin

    2013-01-01

    Genome instability has long been implicated as the main causal factor in aging. Somatic cells are continuously exposed to various sources of DNA damage, from reactive oxygen species to UV radiation to environmental mutagens. To cope with the tens of thousands of chemical lesions introduced into the genome of a typical cell each day, a complex network of genome maintenance systems acts to remove damage and restore the correct base pair sequence. Occasionally, however, repair is erroneous, and such errors, as well as the occasional failure to correctly replicate the genome during cell division, are the basis for mutations and epimutations. There is now ample evidence that mutations accumulate in various organs and tissues of higher animals, including humans, mice, and flies. What is not known, however, is whether the frequency of these random changes is sufficient to cause the phenotypic effects generally associated with aging. The exception is cancer, an age-related disease caused by the accumulation of mutations and epimutations. Here, we first review current concepts regarding the relationship between DNA damage, repair, and mutation, as well as the data regarding genome alterations as a function of age. We then describe a model for how randomly induced DNA sequence and epigenomic variants in the somatic genomes of animals can result in functional decline and disease in old age. Finally, we discuss the genetics of genome instability in relation to longevity to address the importance of alterations in the somatic genome as a causal factor in aging and to underscore the opportunities provided by genetic approaches to develop interventions that attenuate genome instability, reduce disease risk, and increase life span. PMID:23398157

  11. Gas turbine combustion instability

    SciTech Connect

    Richards, G.A.; Lee, G.T.

    1996-09-01

    Combustion oscillations are a common problem in development of LPM (lean premix) combustors. Unlike earlier, diffusion style combustors, LPM combustors are especially susceptible to oscillations because acoustic losses are smaller and operation near lean blowoff produces a greater combustion response to disturbances in reactant supply, mixing, etc. In ongoing tests at METC, five instability mechanisms have been identified in subscale and commercial scale nozzle tests. Changes to fuel nozzle geometry showed that it is possible to stabilize combustion by altering the timing of the feedback between acoustic waves and the variation in heat release.

  12. 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 . PMID:27364424

  13. Surface instabilities and nuclear multifragmentation

    SciTech Connect

    Moretto, L.G.; Tso, K.; Colonna, N.; Wozniak, G.J.

    1992-03-01

    Central heavy-ion collisions, as described by a Boltzman-Nordheim-Vlasov calculation, form nuclear disks that break up into several fragments due to surface instabilities of the Rayleigh-Taylor kind. We demonstrate that a sheet of liquid, nuclear or otherwise, stable in the limit of infinitely sharp surfaces, becomes unstable due to surface-surface interactions. The onset of this instability is determined analytically. The relevance of these instabilities to nuclear multifragmentation is discussed.

  14. How I do it: Anterior pull-through tympanoplasty for anterior eardrum perforations.

    PubMed

    Harris, Jeffrey P; Wong, Yu-Tung; Yang, Tzong-Hann; Miller, Mia

    2016-04-01

    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). PMID:26988908

  15. 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.

  16. Editorial Commentary: Multidirectional Shoulder Instability.

    PubMed

    Lubowitz, James H

    2015-12-01

    Multidirectional shoulder instability responds to physical therapy and rehabilitation. For patients who fail rehabilitation, arthroscopic capsular plication seems the treatment of choice. PMID:26652151

  17. 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.

  18. Editorial Commentary: Does Early Arthroscopy of Subtle Instability in High Ankle Sprains Hasten Return to Play in Elite Athletes?

    PubMed

    Feldman, Michael D

    2016-04-01

    Anterior inferior tibial fibular ligament tenderness to palpation, a positive squeeze test, and a positive external rotation test correlate well with syndesmosis instability after high ankle sprain. However, it is still unknown whether subtle unstable high ankle sprains (grade IIB) could heal satisfactorily with nonoperative treatment and whether their recovery would be prolonged compared with operative treatment. PMID:27039685

  19. Instability characteristics of fluidelastic instability of tube rows in crossflow

    SciTech Connect

    Chen, S.S.; Jendrzejczyk, J.A.

    1986-04-01

    An experimental study is reported to investigate the jump phenomenon in critical flow velocities for tube rows with different pitch-to-diameter ratios and the excited and intrinsic instabilities for a tube row with a pitch-to-diameter ratio of 1.75. The experimental data provide additional insights into the instability phenomena of tube arrays in crossflow. 9 refs., 10 figs.

  20. 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

  1. Hip replacement by a minimal anterior approach.

    PubMed

    Paillard, P

    2007-08-01

    The mini-incision anterior approach in total hip replacement is not new, but uses a shorter incision than the traditional Hueter approach, typically only 6-8 cm in length. Despite its size, the single anterior incision allows good exposure. It is very atraumatic, preserves muscles and tendons, and allows the patient early mobilisation and fast postoperative recovery. Although, a special table (e.g., a Judet table) and specific tools (e.g., a curved reamer) are needed to perform hip replacement via the mini-anterior approach, any kind of hip prosthesis (cemented or uncemented) can be implanted. As there is a significant learning curve in mastering the mini-incision anterior approach, surgeons are advised to start with a longer incision and then to decrease its length with increasing experience. PMID:17657491

  2. Anterior Cervical Discectomy and Fusion with Plating

    MedlinePlus Videos and Cool Tools

    Anterior Cervical Discectomy and Fusion with Plating Broward Health Medical Center Fort Lauderdale, FL November 17, 2011 I'm Dr. Matthew Moore, head of the Spine Care Center here at North Broward Medical Center. And ...

  3. Secondary anterior crocodile shagreen of Vogt.

    PubMed Central

    Tripathi, R C; Bron, A J

    1975-01-01

    The clincopathological features and pathogenesis of secondary mosaic degeneration of the cornea (anterior crocodile shagreen of Vogt) are described. The structural basis for the normal anterior corneal mosaic pattern seems to lie in the particular arrangement of many prominent collagen lamellae of the anterior stroma that thake an oblique course to gain insertion into Bowman's layer. Since, at normal intraocular pressure, Bowman's layer is under tension, when viewed from the anterior surface the cornea appears smooth. By releasing the tension, however, a reproducible polygonal ridge pattern becomes manifest. It is suggested that a prolonged phthisical state of the eye is one condition wherein the mosaic pattern may become permanent and that, as a secondary event, this is followed by irregular calcification of Bowman's layer which particularly involves the ridges projecting into the epithelium. Biomicroscopically these ridges corresponded to the branching reticular arrangement of the mosaic opacities. Images PMID:1079137

  4. Inverted liver with suprahepatic, anteriorly displaced gallbladder.

    PubMed

    Hibbs, Harold; Ahmad, Usman

    2010-01-01

    A suprahepatic, anteriorly displaced gallbladder in association with an inverted liver is an extremely rare congenital anomaly. We report the clinical and radiologic findings associated with a 78-year-old woman presenting with shortness of breath, desaturation, hypercapnia and hypoxemia. An abnormal chest radiograph demonstrated right hemi-diaphragmatic elevation consistent with a possible eventration. Subsequent imaging by computed tomography (CT) demonstrated an inverted liver with an anteriorly displaced, suprahepatic gallbladder. PMID:20666167

  5. Erlotinib-related bilateral anterior uveitis

    PubMed Central

    Ali, Kashif; Kumar, Indu; Usman-Saeed, Muniba; Usman Saeed, Muhammad

    2011-01-01

    The authors report the case of a 68-year-old woman with secondary adenocarcinoma of the lungs from an unknown primary. Erlotinib was started which produced symptoms suggestive of uveitis. Erlotinib was stopped and restarted a month later at a lower dose, which resulted in severe bilateral anterior uveitis. The uveitis settled after stopping erlotinib and treatment with topical steroids and cycloplegics. To the best of the authors’ knowledge, this is the first case of erlotinib-related anterior uveitis. PMID:22694887

  6. Efficacy of Titanium Mesh Cages for Anterior Column Reconstruction after Thoracolumbar Corpectomy

    PubMed Central

    2016-01-01

    Study Design This retrospective study was conducted to determine the safety and efficacy of titanium cage reconstruction and anterior plating after thoracolumbar corpectomy. Purpose To study the clinical and radiological outcome of anterior column reconstruction after thoracolumbar corpectomy. Overview of Literature Anterior column reconstruction aims to optimize neural decompression with adequate stabilization. Methods A series of 16 patients underwent reconstruction after thoracolumbar corpectomy to treat injury due to trauma (n=10), tuberculosis (n=3), and tumor (n=3). The average duration of follow-up was 18 months (range, 8–58 months). The degree of kyphosis, construct height, and the subsidence of the cage in relation to the vertebral endplates were measured. The approach was thoracoabdominal in 10 cases and retroperitoneal in 6 cases. Results Four patients were neurologically intact with Frankel grade E on admission, and all remained intact postoperatively. Of the 6 patients with Frankel grade D, all fully recovered full motor and sensory functions. Of the 6 patients with Frankel grade C, three improved one grade and the other three improved two grades. The mean height of the vertebra before surgery was 41 mm and the mean construct height immediately after surgery and at follow-up was 47 mm and 44 mm, respectively. Solid fusion was observed in all patients. The sagittal alignment of the fractured segment was restored immediately after surgery as a significant decrease in the local kyphotic angle. Conclusions Anterior instrumentation is an effective and safe treatment for thoracolumbar instability with satisfactory clinical and radiological outcomes. PMID:26949463

  7. 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

  8. Anterior capsular defect with acute anterior subcapsular cataract in herpetic keratouveitis

    PubMed Central

    Arora, Tarun; Sharma, Namrata; Arora, Supriya; Titiyal, Jeewan S

    2014-01-01

    A 20-year-old man presented with a recurrent episode of herpetic keratouveitis in his right eye. The patient was treated with oral acyclovir and topical steroids. One week later the patient reported a sudden diminution of vision. Slitlamp biomicroscopy revealed the presence of a central anterior capsular defect and anterior subcapsular cataract. Dosage of steroids was temporarily increased and progression of cataract monitored. Subsequently, the anterior chamber reaction decreased and steroids were tapered. PMID:25228677

  9. Anterior and posterior fixation for delayed treatment of posterior atlantoaxial dislocation without fracture.

    PubMed

    Yu, Hai Ming; Malhotra, Karan; Butler, Joseph S; Wu, Shi Qiang

    2015-01-01

    Posterior atlantoaxial dislocation (PAAD) without fracture of the odontoid process is a rare injury. Authors have variously reported closed or open reduction, followed by either anterior or posterior fixation, but there is no consensus on best treatment. We present a particularly unstable case of PAAD. Open reduction through a retropharyngeal approach with odontoidectomy was required for reduction. Anterior fixation with transarticular lag screws was required prior to posterior fixation with pedicle screws. Despite non-compliance with postoperative immobilisation, imaging at 20-month follow-up confirmed solid fusion. The patient is pain-free with a good range of movement of the neck and has returned to a manual job. Our case had a greater degree of instability than was previously reported, which necessitated 360° fixation. This is the first reported case of this treatment strategy, which provided a very stable fixation allowing fusion despite early movement and without causing undue stiffness. PMID:26516249

  10. 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.

  11. Cohabitation and Children's Family Instability

    ERIC Educational Resources Information Center

    Kelly Raley, R.; Wildsmith, Elizabeth

    2004-01-01

    This study estimates how much children's family instability is missed when we do not count transitions into and out of cohabitation, and examines early life course trajectories of children to see whether children who experience maternal cohabitation face more family instability than children who do not. Using data from the 1995 National Survey of…

  12. 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.

  13. Instability of liquid crystal elastomers

    NASA Astrophysics Data System (ADS)

    An, Ning; Li, Meie; Zhou, Jinxiong

    2016-01-01

    Nematic liquid crystal elastomers (LCEs) contract in the director direction but expand in other directions, perpendicular to the director, when heated. If the expansion of an LCE is constrained, compressive stress builds up in the LCE, and it wrinkles or buckles to release the stored elastic energy. Although the instability of soft materials is ubiquitous, the mechanism and programmable modulation of LCE instability has not yet been fully explored. We describe a finite element method (FEM) scheme to model the inhomogeneous deformation and instability of LCEs. A constrained LCE beam working as a valve for microfluidic flow, and a piece of LCE laminated with a nanoscale poly(styrene) (PS) film are analyzed in detail. The former uses the buckling of the LCE beam to occlude the microfluidic channel, while the latter utilizes wrinkling or buckling to measure the mechanical properties of hard film or to realize self-folding. Through rigorous instability analysis, we predict the critical conditions for the onset of instability, the wavelength and amplitude evolution of instability, and the instability patterns. The FEM results are found to correlate well with analytical results and reported experiments. These efforts shed light on the understanding and exploitation of the instabilities of LCEs.

  14. 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.

  15. 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

  16. Plateau Rayleigh instability simulation.

    PubMed

    Mead-Hunter, Ryan; King, Andrew J C; Mullins, Benjamin J

    2012-05-01

    The well-known phenomena of Plateau-Rayleigh instability has been simulated using computational fluid dynamics (CFD). The breakup of a liquid film into an array of droplets on a cylindrical element was simulated using a volume-of-fluid (VOF) solver and compared to experimental observations and existing theory. It is demonstrated that the VOF method can correctly predict the breakup of thins films into an array of either axisymmetric droplets or clam-shell droplets, depending on the surface energy. The existence of unrealistically large films is precluded. Droplet spacing was found to show reasonable agreement with theory. Droplet motion and displacement under fluid flow was also examined and compared to that in previous studies. It was found that the presence of air flow around the droplet does not influence the stable film thickness; however, it reduces the time required for droplet formation. Novel relationships for droplet displacement were derived from the results. PMID:22512475

  17. 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

  18. 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.

  19. 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.

  20. Treatment of craniocervical instability using a posterior-only approach: report of 3 cases.

    PubMed

    Young, Richard M; Sherman, Jonathan H; Wind, Joshua J; Litvack, Zachary; O'Brien, Joseph

    2014-08-01

    The object of this study was to demonstrate that a posterior-only approach for craniocervical junction pathology is feasible with intraoperative reduction. The authors reviewed 3 cases of craniocervical instability. All patients had craniocervical instability according to radiological imaging and various methods of measurement, with results outside the normal range. Posterior instrumentation aided the intraoperative reduction techniques while maintaining structural integrity and the desired fusion construct. No anterior approach was necessary in any of the patients. Neurological symptoms resolved in two patients and significantly improved in another. Follow-up imaging demonstrated stable constructs. There are many approaches to anterior cervical pathology at the craniocervical junction. Posterior instrumented reduction and stabilization of the occipitocervical spine can be safely achieved, obviating the need for a transoral approach in the setting of craniocervical junction settling. PMID:24785968

  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. Differential expression of extracellular matrix genes in glenohumeral capsule of shoulder instability patients.

    PubMed

    Belangero, Paulo Santoro; Leal, Mariana Ferreira; Figueiredo, Eduardo Antônio; Cohen, Carina; Andreoli, Carlos Vicente; Smith, Marília Cardoso; Pochini, Alberto de Castro; Ejnisman, Benno; Cohen, Moises

    2016-07-01

    Anterior shoulder instability is a common orthopedic problem. After a traumatic shoulder dislocation, patients present a plastic deformation of the capsule. The shoulder instability biology remains poorly understood. We evaluated the expression of genes that encode the cartilage oligomeric matrix protein (COMP), fibronectin 1 (FN1), tenascin C (TNC) and tenascin XB (TNXB) in the glenohumeral capsule of anterior shoulder instability patients and controls. Moreover, we investigated the associations between gene expression and clinical parameters. The gene expression was evaluated by quantitative reverse transcription-polymerase chain reaction in the antero-inferior (macroscopically injured region), antero-superior and posterior regions of the capsule of 29 patients with shoulder instability and 8 controls. COMP expression was reduced and FN1 and TNC expression was increased in the antero-inferior capsule region of cases compared to controls (p < 0.05). TNC expression was increased in the posterior capsule portion of shoulder instability patients (p = 0.022). COMP expression was reduced in the antero-inferior region compared to the posterior region of shoulder instability patients (p = 0.007). In the antero-inferior region, FN1 expression was increased in the capsule of patients with more than one year of symptoms (p = 0.003) and with recurrent dislocations (p = 0.004) compared with controls. FN1 and TNXB expression was correlated with the duration of symptoms in the posterior region (p < 0.05). Thus, COMP, FN1, TNC and TNXB expression was altered across the capsule of shoulder instability patients. Dislocation episodes modify FN1, TNC and TNXB expression in the injured tissue. COMP altered expression may be associated with capsule integrity after shoulder dislocation, particularly in the macroscopically injured portion. PMID:27093129

  3. 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.

  4. Basic biomechanic principles of knee instability.

    PubMed

    Zlotnicki, Jason P; Naendrup, Jan-Hendrik; Ferrer, Gerald A; Debski, Richard E

    2016-06-01

    Motion at the knee joint is a complex mechanical phenomenon. Stability is provided by a combination of static and dynamic structures that work in concert to prevent excessive movement or instability that is inherent in various knee injuries. The anterior cruciate ligament (ACL) is a main stabilizer of the knee, providing both translational and rotatory constraint. Despite the high volume of research directed at native ACL function, pathogenesis and surgical reconstruction of this structure, a gold standard for objective quantification of injury and subsequent repair, has not been demonstrated. Furthermore, recent studies have suggested that novel anatomic structures may play a significant role in knee stability. The use of biomechanical principles and testing techniques provides essential objective/quantitative information on the function of bone, ligaments, joint capsule, and other contributing soft tissues in response to various loading conditions. This review discusses the principles of biomechanics in relation to knee stability, with a focus on the objective quantification of knee stability, the individual contributions of specific knee structures to stability, and the most recent technological advances in the biomechanical evaluation of the knee joint. PMID:27007474

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

    PubMed Central

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

    2014-01-01

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

  6. 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.

  7. Yet another instability in glasma

    NASA Astrophysics Data System (ADS)

    Tsutsui, Shoichiro; Iida, Hideaki; Kunihiro, Teiji; Ohnishi, Akira

    2014-09-01

    In relativistic heavy ion collisions (HIC), hydrodynamic models can describe many experimental data and suggest that the quark-gluon plasma formed at RHIC and LHC is almost perfect fluid. We need very short thermalization time and far-from-equilibrium dynamics may be important in thermalization processes of HIC. In the earliest stages of HIC, classical gluon dynamics is dominant and many types of instabilities emerge there. These instabilities may strongly affect the later stages of dynamics; realization of chaoticity and field-particle conversions. We investigate instabilities of classical gluon fields under the homogeneous, but time dependent background color magnetic fields. The background field become periodic function of time and we can analyze the stability of fluctuations based on the Floquet theory which consists the basis of the Bloch theory. As a result, we get the complete structure of instability bands for physical degrees of freedom appearing from parametric resonance. We also find that the parametric instabilities considered here have different natures from the several known instabilities; Weibel and Nielsen-Olesen instabilities. We also discuss some implications of parametric resonance to the particle productions in HIC.

  8. Warfare-related secondary anterior cranioplasty

    PubMed Central

    Ebrahimi, Ali; Nejadsarvari, Nasrin; Rasouli, Hamid Reza; Ebrahimi, Azin

    2016-01-01

    Background: Anterior cranial bone defects secondary to global war cranial defects pose a unique reconstructive challenge. The objective of this study was to evaluate the outcomes of alloplastic reconstructions of cranial bone with titanium mesh and fat graft after warfare-related cranial trauma. Patients and Methods: Thirty-five patients at the plastic and reconstructive surgery ward of our hospital underwent anterior cranioplasty with titanium mesh with or without fat grafts from lower abdominal wall. Inclusion criteria were anterior cranial bone defect due to warfare injuries, the mean age of these patients was 31 years (range, 23–48 years). Ninety-five percent were male, and 5% were female. Average follow-up was 12 months. Fat grafts were used to help obliterate endocranial dead spaces. Results: Twenty-five patients (71%) had more than 0.5 cm dead space under cranial defects, and we used fat graft under the titanium mesh. The majority groups of patients (80%) were injured as a result of previous explosive device blasts with or without neurosurgical procedures in the past. The average patient age was 31 years, and 95% of patients were male. The mean anterior cranial defect size was 6 cm × 8 cm, and there were no wound infection or flap necrosis after operations. Conclusion: We recommend this procedure (titanium mesh with or without fat graft) for warfare injured cranial defects in secondary anterior cranial reconstructions. Fat grafts eliminates dead space and reduce secondary complications. PMID:27563609

  9. New instability of Saturn's ring

    SciTech Connect

    Goertz, C.K.; Morfill, G.

    1988-05-01

    Perturbations in the Saturn ring's mass density are noted to be prone to instabilities through the sporadic elevation of submicron-size dust particles above the rings, which furnishes an effective angular momentum exchange between the rings and Saturn. The dust thus elevated from the ring settles back onto it at a different radial distance. The range of wavelength instability is determinable in light of the dust charge, the average radial displacement of the dust, and the fluctuation of these quantities. It is suggested that at least some of the B-ring's ringlets may arise from the instability.

  10. Microbunching Instability in Velocity Bunching

    SciTech Connect

    Xiang, D; Wu, J.; /SLAC

    2009-05-26

    Microbunching instability is one of the most challenging threats to FEL performances. The most effective ways to cure the microbunching instability include suppression of the density modulation sources and suppression of the amplification process. In this paper we study the microbunching instability in velocity bunching. Our simulations show that the initial current and energy modulations are suppressed in velocity bunching process, which may be attributed to the strong plasma oscillation and Landau damping from the relatively low beam energy and large relative slice energy spread. A heating effect that may be present in a long solenoid is also preliminarily analyzed.

  11. Shock-induced crystalline instabilities

    NASA Astrophysics Data System (ADS)

    Ravelo, Ramon; Holian, Brad Lee; Germann, Timothy C.

    2007-03-01

    Uniaxial deformations of single crystals such as those produced under planar shock loading can produce structural instabilities which compete with defect nucleation mechanisms. In fcc single crystals under (110) shock loading, the resulting body-centered orthorhombic crystal structure develops a long-wavelength dynamical instability associated with tetragonal shear distortions, which occurs at lower strains (pressures) than those predicted by the vanishing of the elastic constants at finite pressure (stiffness coefficients). The criterion for these instabilities is derived and verified by equilibrium and non-equilibrium molecular dynamics simulations [2]J. Wang, S. Yip, S.R. Phillpot, D. Wolf, Phys. Rev. Lett. 71, 4182 (1993)

  12. 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.

  13. Sheared Electroconvective Instability

    NASA Astrophysics Data System (ADS)

    Kwak, Rhokyun; Pham, Van Sang; Lim, Kiang Meng; Han, Jongyoon

    2012-11-01

    Recently, ion concentration polarization (ICP) and related phenomena draw attention from physicists, due to its importance in understanding electrochemical systems. Researchers have been actively studying, but the complexity of this multiscale, multiphysics phenomenon has been limitation for gaining a detailed picture. Here, we consider electroconvective(EC) instability initiated by ICP under pressure-driven flow, a scenario often found in electrochemical desalinations. Combining scaling analysis, experiment, and numerical modeling, we reveal unique behaviors of sheared EC: unidirectional vortex structures, its size selection and vortex propagation. Selected by balancing the external pressure gradient and the electric body force, which generates Hagen-Poiseuille(HP) flow and vortical EC, the dimensionless EC thickness scales as (φ2 /UHP)1/3. The pressure-driven flow(or shear) suppresses unfavorably-directed vortices, and simultaneously pushes favorably-directed vortices with constant speed, which is linearly proportional to the total shear of HP flow. This is the first systematic characterization of sheared EC, which has significant implications on the optimization of electrodialysis and other electrochemical systems.

  14. 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.

  15. Acute and chronic lateral ankle instability in the athlete.

    PubMed

    Chan, Keith W; Ding, Bryan C; Mroczek, Kenneth J

    2011-01-01

    Ankle sprain injuries are the most common injury sustained during sporting activities. Three-quarters of ankle injuries involve the lateral ligamentous complex, comprised of the anterior talofibular ligament (ATFL), the calcaneofibular ligament (CFL), and the posterior talofibular ligament (PTFL). The most common mechanism of injury in lateral ankle sprains occurs with forced plantar flexion and inversion of the ankle as the body's center of gravity rolls over the ankle. The ATFL followed by the CFL are the most commonly injured ligaments. Eighty percent of acute ankle sprains make a full recovery with conservative management, while 20% of acute ankle sprains develop mechanical or functional instability, resulting in chronic ankle instability. Treatment of acute ankle sprains generally can be successfully managed with a short period of immobilization that is followed by functional rehabilitation. Patients with chronic ankle instability who fail functional rehabilitation are best treated with a Brostrom-Gould anatomic repair or, in those patients with poor tissue quality or undergoing revision surgery, an anatomic reconstruction. PMID:21332435

  16. Traumatic graft dehiscence after anterior lamellar keratoplasty.

    PubMed

    Prasher, Pawan; Muftuoglu, Orkun; Mootha, V Vinod

    2009-02-01

    A 64-year-old man underwent anterior lamellar keratoplasty using the Melles technique for corneal scar secondary to healed bacterial keratitis in the left eye. Two months postoperatively, the patient presented with blurry vision in the left eye after a fall in the bathroom. The uncorrected visual acuity was 20/400 in the left eye, and the external examination showed periorbital swelling with ecchymosis. Slit-lamp examination revealed an absent graft, a circular crater in the center, and a fragment of suture on the temporal edge of the crater. The Seidel test was negative, and there was no sign of infection. The anterior segment optical coherence tomography showed intact residual stroma with slight forward protrusion. The patient underwent repeat anterior lamellar corneal transplantation with improvement in uncorrected visual acuity of 20/100 and best spectacle-corrected visual acuity of 20/70 in the left eye 3 months postoperatively. PMID:19158577

  17. Anterior eye development and ocular mesenchyme

    PubMed Central

    Cvekl, Aleš; Tamm, Ernst R.

    2007-01-01

    Summary During development of the anterior eye segment, cells that originate from the surface epithelium or the neuroepithelium need to interact with mesenchymal cells, which predominantly originate from the neural crest. Failures of proper interaction result in a complex of developmental disorders such Peters’ anomaly, Axenfeld-Rieger’s syndrome or aniridia. Here we review the role of transcription factors that have been identified to be involved in the coordination of anterior eye development. Among these factors is PAX6, which is active in both epithelial and mesenchymal cells during ocular development, albeit at different doses and times. We propose that PAX6 is a key element that synchronizes the complex interaction of cell types of different origin, which are all needed for proper morphogenesis of the anterior eye. We discuss several molecular mechanisms that might explain the effects of haploinsufficiency of PAX6 and other transcription factors, and the broad variation of the resulting phenotypes. PMID:15057935

  18. BILATERAL ANTERIOR GLENOHUMERAL DISLOCATION: CLINICAL CASE

    PubMed Central

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

    2015-01-01

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

  19. Clinical Outcomes of High Tibial Osteotomy for Knee Instability

    PubMed Central

    Dean, Chase S.; Liechti, Daniel J.; Chahla, Jorge; Moatshe, Gilbert; LaPrade, Robert F.

    2016-01-01

    Background: In recent years there has been an increasing interest in high tibial osteotomy (HTO) to treat patients with chronic knee instability due to posterolateral corner (PLC), posterior cruciate ligament (PCL), and anterior cruciate ligament (ACL) insufficiencies with concurrent malalignment in the coronal and/or sagittal plane. Purpose: To perform a systematic review of the use of HTO for the treatment of knee ligament instability with concurrent malalignment. Study Design: Systematic review; Level of evidence, 4. Methods: A systematic review of the literature was conducted for the treatment of combined knee ligament instability and malalignment with HTO using the Cochrane Central Register of Controlled Trials, PubMed, and MEDLINE (1980 to present); the queries were performed in July 2015. Terms searched included the following: high or proximal tibial osteotomy, unstable, instability, laxity, subluxation, tibial slope, and malalignment, in the knee joint. Inclusion criteria were as follows: HTO to treat instability of the knee joint in the sagittal and/or coronal plane, minimum 2-year follow-up with reported outcomes measures, English language, and human studies. Animal, basic science, and cadaveric studies were excluded as well as editorials, reviews, expert opinions, surveys, special topics, letters to the editor, and correspondence. Results: The search resulted in 460 studies. After applying exclusion criteria and removing duplicates, 13 studies were considered. Of the studies reviewed, knee ligament pathologies, previous surgeries, and measurement of knee stability were heterogeneous. However, all studies reported an improvement in knee stability after HTO. Most studies reported improvement in outcome scores. However, other studies did not provide preoperative scores for comparison. Reported complication rates ranged from 0% to 47%. Conclusion: Although HTO has been highly advocated and used in treating patients with ligamentous knee instability, there

  20. Instability mechanisms in swirling flows

    NASA Astrophysics Data System (ADS)

    Gallaire, F.; Chomaz, J.-M.

    2003-09-01

    We investigate the stability of the screened Rankine vortex with added plug flow where the azimuthal velocity decreases abruptly outside the core of the vortex. The jump in circulation is known to induce centrifugal and azimuthal Kelvin-Helmholtz instabilities. Their effect on the stability of the different azimuthal wave number m is discussed using physical considerations associated with asymptotic expansions and numerical computations of the dispersion relation. It is shown that the axial shear and centrifugal instability are active for all m, and that modes with |m|⩾2 are also destabilized by azimuthal shear. In contrast, the bending modes m=±1 are stabilized by a coupling with Kelvin waves in the core. Effects of rotation on the absolute/convective transition are also discussed. The absolute instability of positive helical modes is seen to be promoted by centrifugal instability and azimuthal shear.

  1. Microwave instability near transition energy

    SciTech Connect

    Wei, J.; Lee, S.Y.

    1989-01-01

    Monte Carlo simulation for the microwave instability agrees with analytic calculation solving the Vlasov equation, provided that bunch shape distortion due to coupling is taken into account. 9 refs., 2 figs.

  2. 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.

  3. 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.

  4. Flare instability and driving mechanism

    NASA Astrophysics Data System (ADS)

    Raychaudhuri, Probhas

    A mechanism is described for the generation of solar flares in which a Buneman instability is produced by electrons moving faster than thermal speed. A trapped population of particles accelerates in the magnetic field of active solar regions causing a streaming of ions relative to electrons which moves and heats the electrons. The theoretical argument also concludes that instability at the inner solar core directly bears on solar activities at the outer heliosphere.

  5. Stability and instability in evolution.

    PubMed

    Benci, V; Galleni, L

    1998-10-21

    In this paper we propose a mechanism which tries to explain the presence of periods of stability and instability which occur during the evolution of living forms. According to the Gaia hypothesis there are feedback mechanisms which stabilise the biosphere. Adding the presence of parameters which are out of control of the biosphere and of different time-scales, we propose a model which might explain the periods of instability. PMID:9790828

  6. 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.

  7. 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.

  8. Pattern Formation in Convective Instabilities

    NASA Astrophysics Data System (ADS)

    Friedrich, R.; Bestehorn, M.; Haken, H.

    The present article reviews recent progress in the study of pattern formation in convective instabilities. After a brief discussion of the relevant basic hydrodynamic equations as well as a short outline of the mathematical treatment of pattern formation in complex systems the self-organization of spatial and spatio-temporal structures due to convective instabilities is considered. The formation of various forms of convective patterns arising in the Bénard experiment, i.e. in a horizontal fluid layer heated from below, is discussed. Then the review considers pattern formation in the Bénard instability in spherical geometries. In that case it can be demonstrated how the interaction among several convective cells may lead to time dependent as well as chaotic evolution of the spatial structures. Finally, the convective instability in a binary fluid mixture is discussed. In contrast to the instability in a single component fluid the instability may be oscillatory. In that case convection sets in in the form of travelling wave patterns which in addition to a complicated and chaotic temporal behaviour exhibit more or less spatial irregularity already close to threshold.

  9. Elastic instabilities in rubber

    NASA Astrophysics Data System (ADS)

    Gent, Alan

    2009-03-01

    Materials that undergo large elastic deformations can exhibit novel instabilities. Several examples are described: development of an aneurysm on inflating a rubber tube; non-uniform stretching on inflating a spherical balloon; formation of internal cracks in rubber blocks at a critical level of triaxial tension or when supersaturated with a dissolved gas; surface wrinkling of a block at a critical amount of compression; debonding or fracture of constrained films on swelling, and formation of ``knots'' on twisting stretched cylindrical rods. These various deformations are analyzed in terms of a simple strain energy function, using Rivlin's theory of large elastic deformations, and the results are compared with experimental measurements of the onset of unstable states. Such comparisons provide new tests of Rivlin's theory and, at least in principle, critical tests of proposed strain energy functions for rubber. Moreover the onset of highly non-uniform deformations has serious implications for the fatigue life and fracture resistance of rubber components. [4pt] References: [0pt] R. S. Rivlin, Philos. Trans. Roy. Soc. Lond. Ser. A241 (1948) 379--397. [0pt] A. Mallock, Proc. Roy. Soc. Lond. 49 (1890--1891) 458--463. [0pt] M. A. Biot, ``Mechanics of Incremental Deformations'', Wiley, New York, 1965. [0pt] A. N. Gent and P. B. Lindley, Proc. Roy. Soc. Lond. A 249 (1958) 195--205. [0pt] A. N. Gent, W. J. Hung and M. F. Tse, Rubb. Chem. Technol. 74 (2001) 89--99. [0pt] A. N. Gent, Internatl. J. Non-Linear Mech. 40 (2005) 165--175.

  10. 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.

  11. An analytical description of hydrodynamic instabilities

    NASA Astrophysics Data System (ADS)

    Bulanov, S. V.; Sasorov, P. V.

    The proper approach to the investigation of the nonlinear stage of hydrodynamic instabilities in a plasma has been discussed. Both the Buneman instability and the beam instability have been considered. A similarity between the nonlinear stage of the beam plasma instability and the process of self-modulation and self-focusing of nonlinear waves is revealed.

  12. Does surgery for instability of the shoulder truly stabilize the glenohumeral joint?: A prospective comparative cohort study.

    PubMed

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

    2016-08-01

    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

  13. Anterior subtalar dislocation with comminuted fracture of the anterior calcaneal process.

    PubMed

    Hui, Siu Hung Kenneth; Lui, Tun Hing

    2016-01-01

    Anterior subtalar dislocation is a very rare injury. We report a case of an 81-year-old woman who had her right foot injured during a motor vehicle accident. Radiographs showed anterior subtalar dislocation with comminuted fracture of the anterior calcaneal process. The dislocation was closely reduced and protected by a short leg cast. One year postinjury, the patient had only mild pain when walking on uneven ground. There was mild tenderness over the lateral heel. Subtalar motion was mildly painful. There was no pain with ankle motion. PMID:26887882

  14. Anterior Cervical Spine Surgery for Degenerative Disease: A Review

    PubMed Central

    SUGAWARA, Taku

    Anterior cervical spine surgery is an established surgical intervention for cervical degenerative disease and high success rate with excellent long-term outcomes have been reported. However, indications of surgical procedures for certain conditions are still controversial and severe complications to cause neurological dysfunction or deaths may occur. This review is focused mainly on five widely performed procedures by anterior approach for cervical degenerative disease; anterior cervical discectomy, anterior cervical discectomy and fusion, anterior cervical corpectomy and fusion, anterior cervical foraminotomy, and arthroplasty. Indications, procedures, outcomes, and complications of these surgeries are discussed. PMID:26119899

  15. Balanitis xerotica obliterans involving anterior urethra.

    PubMed

    Herschorn, S; Colapinto, V

    1979-12-01

    Balanitis xerotica obliterans (BXO) is known to affect the urethral meatus, glans, and prepuce. We describe a case of biopsy-proved BXO that involves not only the usual areas but the anterior urethra as well. Of added interest is the subsequent development of squamous cell carcinoma in the fossa navicularis. The literature is reviewed. PMID:516213

  16. Performing an Anterior Cervical Discectomy and Fusion.

    PubMed

    Schroeder, Gregory D; Kurd, Mark F; Millhouse, Paul W; Vaccaro, Alexander R; Hilibrand, Alan S

    2016-06-01

    An anterior cervical discectomy and fusion is one of the most common procedures performed in spine surgery. It allows for a direct decompression of the spinal cord and the neural foramen. When performed properly, the results of this procedure are some of the best in spine surgery. PMID:27187618

  17. A rare case of anterior chamber dirofilariasis

    PubMed Central

    Das, Dipankar; Das, Kalyan; Islam, Saidul; Bhattacharjee, Kasturi; Bhattacharjee, Harsha; Das, Shrutanjoy Mohan; Deka, Apurba

    2015-01-01

    We report a rare case of anterior chamber live dirofilariasis presenting as anterior uveitis. A 60-year-old man presented with dimness of vision in the right eye for 1 month. Vision recorded was 6/18 P, N 18 in the right eye. Slit lamp examination of the right eye revealed anterior uveitis with a moving nemathelminthes. The worm was removed live from the anterior chamber under local anesthesia with assisted methyl cellulose delivery and post-operatively, the worm was examined directly under light microscope. Morphometric measurement showed length of the worm was 6.061 mm. A thin, pale, slender worm was diagnosed as immature female Dirofilaria repens and was documented completely. Patient had made an excellent recovery of vision and intraocular inflammation after the surgical removal of the worm. Intraocular infection of dirofilaria is a rare presentation and successful surgical removal of the worm resulted in complete recovery of uveitis and visual status in the affected eye. PMID:25709276

  18. Two cases of isolated anterior cervical hypertrichosis.

    PubMed

    Reddy, Swapna; Antaya, Richard J

    2010-01-01

    Two unrelated Hispanic females, ages 4 and 3 years, respectively, each presented with a solitary patch of excessive terminal hair growth in the midline of the neck. This rare form of congenital localized hypertrichosis, known as anterior cervical hypertrichosis, is reported here as an isolated defect with no other underlying abnormalities. PMID:20796240

  19. Anterior Chamber Live Loa loa: Case Report.

    PubMed

    Kagmeni, G; Cheuteu, R; Bilong, Y; Wiedemann, P

    2016-01-01

    We reported a case of unusual intraocular Loa loa in a 27-year-old patient who presented with painful red eye. Biomicroscopy revealed a living and active adult worm in the anterior chamber of the right eye. After surgical extraction under local anesthesia, parasitological identification confirmed L. loa filariasis. PMID:27441005

  20. Anterior Chamber Live Loa loa: Case Report

    PubMed Central

    Kagmeni, G.; Cheuteu, R.; Bilong, Y.; Wiedemann, P.

    2016-01-01

    We reported a case of unusual intraocular Loa loa in a 27-year-old patient who presented with painful red eye. Biomicroscopy revealed a living and active adult worm in the anterior chamber of the right eye. After surgical extraction under local anesthesia, parasitological identification confirmed L. loa filariasis. PMID:27441005

  1. Clinical therapeutic effects of anterior decompression on spinal osteoporotic fracture and inflammatory cytokines

    PubMed Central

    Liao, Qi; Liu, Shi-Qing; Ming, Jiang-Hua; Chen, Qing; Zhao, Qi; Yang, Yue

    2014-01-01

    Objective: To evaluate the clinical therapeutic effects of anterior decompression on spinal osteoporotic fracture and inflammatory cytokines. Methods: A total of 140 patients with spinal osteoporotic fracture were selected and randomly divided into a treatment group and a control group (n=70). The control group was treated by central corpectomy, and the control group was treated by anterior decompression. Results: The rate of excellent and good outcomes in the treatment group was 94.3%, and that of the control group was 78.6%, which differed significantly (P<0.05). Cobb angle and cord occupancy in the spinal canal of both groups significantly decreased (P<0.05), while height ratio of the injured vertebral body significantly increased (P<0.05). Meanwhile, there were statistically significant inter-group differences (P<0.05). During the three-month follow-up period, the treatment group was significantly less prone to complications such as superficial infection, spinal instability and screw breakage compared with the control group (P<0.05). The postoperative serum MMP-3 and IL-6 levels of both groups significantly decreased compared with those before surgeries (P<0.05), with statistically significant inter-group differences (P<0.05). Conclusion: Compared with central corpectomy, anterior decompression exerted better effects on spinal osteoporotic fracture by improving the prognosis and stabilizing the spine safely, which may be associated with the effectively reduced serum MMP-3 and IL-6 levels. PMID:25225501

  2. L5 vertebral osteomyelitis treated with L5 corpectomy and anterior instrumentation: case report

    PubMed Central

    Crabtree, Kelli L; Spurgeon, Angela; Arzi, Harel; Beaver, Bryan; Arnold, Paul M

    2011-01-01

    Study design: A case report. Objective: Pyogenic osteomyelitis is the most common form of vertebral infection and typically resolves following conservative treatment with antibiotics administered long term and immobilization. In cases of spinal instability, severe neurological deficit or disease refractory to medical management, neurosurgical intervention is warranted. Historically, these patients have undergone radical vertebral debridement and grafting with or without posterior instrumentation. We report the case of a 46-year-old female intravenous drug user presenting with L5 pyogenic osteomyelitis with L5 vertebral compression and cortex retropulsion following L2–L4 laminectomy for epidural abscess 8 weeks prior. Methods: The patient underwent an anterior approach single-stage L5 corpectomy, L4/5 and L5/S1 discectomies, expandable titanium-cage insertion and anterior plating from L4 to the sacrum. Results: The patient recovered without any complications. The infection was successfully eradicated and her fusion remains solid 18 months postoperatively. Conclusions: To our knowledge, this is the first case of L5 vertebral osteomyelitis treated with a single-stage corpectomy and anterior instrumentation. PMID:23637682

  3. Repair of a complete anterior cruciate tear using prolotherapy: a case report

    PubMed Central

    Grote, Walter; Delucia, Rosa; Waxman, Robert; Zgierska, Aleksandra; Wilson, John; Rabago, David

    2010-01-01

    Objective and Importance Surgical reconstruction is considered definitive treatment for anterior cruciate ligament (ACL) tears but precise surgical indications are debated. Some patients are reluctant or inappropriate surgical candidates. Prolotherapy is a non-surgical injection therapy for chronic musculoskeletal pain and instability. This case report documents the non-surgical repair of a torn ACL using prolotherapy and at-home exercise. Clinical Presentation and Intervention The 18 year old female patient sustained a right knee injury during a downhill skiing accident. Magnetic Resonance Imaging (MRI) revealed a high-grade partial versus complete rupture; Lachman exam findings suggested a complete rupture. She deferred surgical treatment. At 21 weeks post-injury, with unstable gait, inability to climb stairs and more than 1 cm anterior drawer test, she consented to undergo prolotherapy injections. She received 7 prolotherapy sessions over a 15 week period. At-home exercises were initiated at the 3rd prolotherapy session. Results The patient improved. Walking on flat ground improved 4 weeks after initiation of prolotherapy; she could ride a stationary bicycle for 30 minutes by 12 weeks. By 15 weeks, the patient had no instability climbing and descending stairs, the anterior drawer test was negative and MRI showed an intact ACL with fibrosis. Subsequently, she returned to full sport activity. Conclusions We document the non-surgical repair of a high-grade partial or complete ACL tear using prolotherapy and at-home exercise. Prolotherapy may be an alternative to surgery in carefully selected patients. This report is consistent with findings of recent pilot-level studies and suggests the need for rigorous clinical trials assessing prolotherapy as treatment for ligament and tendon injury in selected patients. PMID:20802815

  4. Fermi liquids near Pomeranchuk instabilities

    NASA Astrophysics Data System (ADS)

    Reidy, Kelly Elizabeth

    We explore features of a Fermi liquid near generalized Pomeranchuk instabilities (PIs) starting from both ordered and disordered phases. These PIs can be viewed as quantum critical points in parameter space, and thus provide an alternate viewpoint on quantum criticality. We employ the tractable crossing symmetric equation method, which is a non-perturbative diagrammatic many-particle method used to calculate the Fermi liquid interaction functions and scattering amplitudes. We consider both repulsive and attractive underlying interactions of arbitrary strength. Starting from a ferromagnetically ordered ground state, we find that upon approach to an s-wave instability in one critical channel, the system simultaneously approaches instabilities in non-critical channels. We study origins and implications of this "quantum multicriticality". We also find that a nematic (non-s-wave) instability precedes and is driven by Pomeranchuk instabilities in both the s-wave spin and density channels. Finally, we discuss potential applications of our results to physical systems, such as ferromagnetic superconductors.

  5. The Energetics of Centrifugal Instability

    NASA Astrophysics Data System (ADS)

    Dewar, W. K.; Jiao, Y.

    2014-12-01

    A recent study has argued that the California Undercurrent, and poleward eastern boundary currents in general, generate mixing events through centrifugal instability (CI). Conditions favorable for CI are created by the strong horizontal shears developed in turbulent bottom layers of currents flowing in the direction of topographic waves. At points of abrupt topographic change, like promontories and capes, the coastal current separates from the boundary and injects gravitationally stable but dynamically unstable flow into the interior. The resulting finite amplitude development of the instability involves overturnings and diabatic mixing. The purpose of this study is to examine the energetics of CI in order to characterize it as has been done for other instabilities and develop a framework in which to estimate its regional and global impacts. We argue that CI is roughly twice as efficient at mixing as is Kelvin-Helmholtz instability, and that roughly 10% of the initial energy in a CUC-like current is lost to either local mixing or the generation of unbalanced flows. The latter probably leads to non-local mixing. Thus centrifugal instability is an effective process by which energy is lost from the balanced flow and spent in mixing neighboring water masses. We argue the importance of the mixing is regional in nature, but of less importance to the global budgets given its regional specificity.

  6. Current approach in diagnosis and management of anterior uveitis

    PubMed Central

    Agrawal, Rupesh V; Murthy, Somasheila; Sangwan, Virender; Biswas, Jyotirmay

    2010-01-01

    Uveitis is composed of a diverse group of disease entities, which in total has been estimated to cause approximately 10% of blindness. Uveitis is broadly classified into anterior, intermediate, posterior and panuveitis based on the anatomical involvement of the eye. Anterior uveitis is, however, the commonest form of uveitis with varying incidences reported in worldwide literature. Anterior uveitis can be very benign to present with but often can lead to severe morbidity if not treated appropriately. The present article will assist ophthalmologists in accurately diagnosing anterior uveitis, improving the quality of care rendered to patients with anterior uveitis, minimizing the adverse effects of anterior uveitis, developing a decision-making strategy for management of patients at risk of permanent visual loss from anterior uveitis, informing and educating patients and other healthcare practitioners about the visual complications, risk factors, and treatment options associated with anterior uveitis. PMID:20029142

  7. Interfacial Instability during Granular Erosion

    NASA Astrophysics Data System (ADS)

    Lefebvre, Gautier; Merceron, Aymeric; Jop, Pierre

    2016-02-01

    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.

  8. Interfacial instabilities and Kapitsa pendula

    NASA Astrophysics Data System (ADS)

    Krieger, Madison

    2015-11-01

    Determining the critera for onset and amplitude growth of instabilities is one of the central problems of fluid mechanics. We develop a parallel between the Kapitsa effect, in which a pendulum subject to high-frequency low-amplitude vibrations becomes stable in the inverted position, and interfaces separating fluids of different density. It has long been known that such interfaces can be stabilized by vibrations, even when the denser fluid is on top. We demonstrate that the stability diagram for these fluid interfaces is identical to the stability diagram for an appopriate Kapitsa pendulum. We expand the robust, ``dictionary''-type relationship between Kapitsa pendula and interfacial instabilities by considering the classical Rayleigh-Taylor, Kelvin-Helmholtz and Plateau instabilities, as well as less-canonical examples ranging in scale from the micron to the width of a galaxy.

  9. 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. PMID:26919014

  10. 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.

  11. 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.

  12. A Plasma, Magnetorotational Instability Experiment

    NASA Astrophysics Data System (ADS)

    Collins, C.; Forest, C. B.; Kendrick, R.; Seltzman, A.

    2007-11-01

    A new experiment is underway at the University of Wisconsin to investigate the magnetorotational instability in a plasma. Magnetorotational instability (MRI) is a likely mechanism that could account for the observed accretion rates in astrophysical objects. The instability occurs when a weak magnetic field is present, so that tension in perturbed field lines transfers angular momentum outward while mass moves towards the center. In the Plasma Dynamo Experiment Prototype, a cylindrical, axisymmetric, ring cusp confinement geometry is used to produce a large unmagnetized plasma, confined by a highly localized magnetic field at the plasma boundary. The plasma is stirred by a novel axisymmetric electrode set that can control the rotation (angular momentum profile). The feasibility of observing the MRI will be discussed and initial results from a protoype experiment will be presented.

  13. Longitudinal instability in HIF beams

    SciTech Connect

    Smith, L.

    1991-04-01

    In contrast to an electron induction accelerator, in which the particle velocity is virtually constant, the resistive and inductive components of accelerating module impedances can cause instability for an intense non-relativistic heavy ion beam accelerated in a similar structure. Since focusing requirements at the fusion pellet imply a momentum spread {approx lt}3 {times} 10{sup {minus}4} at the end of the accelerator, it is essential to understand and suppress this instability. There is also an economic issue involved for this application; selection of parameters to control the instability must not unduly affect the efficiency and cost of the accelerator. This paper will present the results of analytic and computational work on module impedances, growth rates and feed back (forward) systems. 2 refs., 3 figs.

  14. 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.

  15. Performance through Deformation and Instability

    NASA Astrophysics Data System (ADS)

    Bertoldi, Katia

    2015-03-01

    Materials capable of undergoing large deformations like elastomers and gels are ubiquitous in daily life and nature. An exciting field of engineering is emerging that uses these compliant materials to design active devices, such as actuators, adaptive optical systems and self-regulating fluidics. Compliant structures may significantly change their architecture in response to diverse stimuli. When excessive deformation is applied, they may eventually become unstable. Traditionally, mechanical instabilities have been viewed as an inconvenience, with research focusing on how to avoid them. Here, I will demonstrate that these instabilities can be exploited to design materials with novel, switchable functionalities. The abrupt changes introduced into the architecture of soft materials by instabilities will be used to change their shape in a sudden, but controlled manner. Possible and exciting applications include materials with unusual properties such negative Poisson's ratio, phononic crystals with tunable low-frequency acoustic band gaps and reversible encapsulation systems.

  16. Microsatellite instability in bladder cancer.

    PubMed

    Gonzalez-Zulueta, M; Ruppert, J M; Tokino, K; Tsai, Y C; Spruck, C H; Miyao, N; Nichols, P W; Hermann, G G; Horn, T; Steven, K

    1993-12-01

    Somatic instability at microsatellite repeats was detected in 6 of 200 transitional cell carcinomas of the bladder. Instabilities were apparent as changes in (GT)n repeat lengths on human chromosome 9 for four tumors and as alterations in a (CAG)n repeat in the androgen receptor gene on the X chromosome for three tumors. Single locus alterations were detected in three tumors, while three other tumors revealed changes in two or more loci. In one tumor we found microsatellite instability in all five loci analyzed on chromosome 9. The alterations detected were either minor 2-base pair changes or larger (> 2 base pairs) alterations in repeat length. All six tumors were low stage (Ta-T1), suggesting that these alterations can occur early in bladder tumorigenesis. PMID:8242615

  17. SURGICAL TREATMENT OF PATELLOFEMORAL INSTABILITY

    PubMed Central

    de Andrade, Marco Antônio Percope; de Abreu e Silva, Guilherme Moreira; Freire, Marcelo Machado; Teixeira, Luiz Eduardo Moreira

    2015-01-01

    Objective: To describe functional outcomes following surgical treatment of patients with patellofemoral instability submitted to patellar realignment. Methods: This was a retrospective study evaluating 34 operated knees for patellofemoral instability between 1989 and 2004. The patients were evaluated in the late postoperative period when a functional questionnaire was applied. Results: After a mean follow-up time of 6 years and 5 months, the mean score was 82.94 in the surgical group (p=0.00037). The results of this investigation showed pain relief in 97.05% and low rate of recurrent dislocation (5.88%), although lower scores were seen in intense articular activities (squatting, running and jumping). No patient developed osteoarthritis while being followed up. Conclusion: The procedure for joint described in this paper was shown to be effective for treating patients with recurrent patellofemoral instability. PMID:27077065

  18. 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

  19. 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.

  20. Beam instabilities in hadron synchrotrons

    DOE PAGESBeta

    Metral, E.; T. Argyropoulos; Bartosik, H.; Biancacci, N.; Buffat, X.; Esteban Muller, J. F.; Herr, W.; Iadarola, G.; Lasheen, A.; Li, K.; et al

    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. 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.

  2. Active suppression of compressor instabilities

    NASA Technical Reports Server (NTRS)

    Epstein, A. H.; Ffowcs Williams, J. E.; Greitzer, E. M.

    1986-01-01

    A strategy is proposed for controlling aerodynamic instabilities which limit the useful range of both axial and centrifugal turbomachines. Both local and global instabilities (incipient rotating stall and surge) are analyzed. A theory is developed which shows how an additional disturbance, driven from real time data measured within the machine, can be generated so as to realize a device with characteristics fundamentally different from those of the turbomachine without control; for the particular compressor analyzed, the control led to a 20 percent increase in the extent of the stable operating range. The use of structural dynamics to enhance stability is also discussed.

  3. Anterior Insular Cortex and Emotional Awareness

    PubMed Central

    Gu, Xiaosi; Hof, Patrick R.; Friston, Karl J.; Fan, Jin

    2014-01-01

    This paper reviews the foundation for a role of the human anterior insular cortex (AIC) in emotional awareness, defined as the conscious experience of emotions. We first introduce the neuroanatomical features of AIC and existing findings on emotional awareness. Using empathy, the awareness and understanding of other people’s emotional states, as a test case, we then present evidence to demonstrate: 1) AIC and anterior cingulate cortex (ACC) are commonly coactivated as revealed by a meta-analysis, 2) AIC is functionally dissociable from ACC, 3) AIC integrates stimulus-driven and top-down information, and 4) AIC is necessary for emotional awareness. We propose a model in which AIC serves two major functions: integrating bottom-up interoceptive signals with top-down predictions to generate a current awareness state and providing descending predictions to visceral systems that provide a point of reference for autonomic reflexes. We argue that AIC is critical and necessary for emotional awareness. PMID:23749500

  4. Anterior insular cortex and emotional awareness.

    PubMed

    Gu, Xiaosi; Hof, Patrick R; Friston, Karl J; Fan, Jin

    2013-10-15

    This paper reviews the foundation for a role of the human anterior insular cortex (AIC) in emotional awareness, defined as the conscious experience of emotions. We first introduce the neuroanatomical features of AIC and existing findings on emotional awareness. Using empathy, the awareness and understanding of other people's emotional states, as a test case, we then present evidence to demonstrate: 1) AIC and anterior cingulate cortex (ACC) are commonly coactivated as revealed by a meta-analysis, 2) AIC is functionally dissociable from ACC, 3) AIC integrates stimulus-driven and top-down information, and 4) AIC is necessary for emotional awareness. We propose a model in which AIC serves two major functions: integrating bottom-up interoceptive signals with top-down predictions to generate a current awareness state and providing descending predictions to visceral systems that provide a point of reference for autonomic reflexes. We argue that AIC is critical and necessary for emotional awareness. PMID:23749500

  5. Flap Coverage of Anterior Abdominal Wall Defects

    PubMed Central

    Sacks, Justin M.; Broyles, Justin M.; Baumann, Donald P.

    2012-01-01

    Reconstruction of complex defects of the anterior abdomen is both challenging and technically demanding for reconstructive surgeons. Advancements in the use of pedicle and free tissue transfer along with the use of bioprosthetic and synthetic meshes have provided for novel approaches to these complex defects. Accordingly, detailed knowledge of abdominal wall and lower extremity anatomy in combination with insight into the design, implementation, and limitations of various flaps is essential to solve these complex clinical problems. Although these defects can be attributed to a myriad of etiologic factors, the objectives in abdominal wall reconstruction are consistent and include the restoration of abdominal wall integrity, protection of intraabdominal viscera, and the prevention of herniation. In this article, the authors review pertinent anatomy and the various local, regional, and distant flaps that can be utilized in the reconstruction of these complex clinical cases of the anterior abdomen. PMID:23372457

  6. Cataract Surgery in Anterior Megalophthalmos: A Review

    PubMed Central

    GALVIS, Virgilio; TELLO, Alejandro; M. RANGEL, Carlos

    2015-01-01

    Anterior megalophthalmos is characterized by megalocornea associated with a very broad anterior chamber and ciliary ring elongation. It is also called X-linked megalocornea. It is accompanied by early development of cataracts, zonular anomalies, and, rarely, vitreoretinal disorders. Subluxation of a cataract can occur in cataract surgery because of zonular weakness. In addition, in most patients, standard intraocular lens (IOL) decentration is a risk because of the enlarged sulcus and capsular bag. These unique circumstances make cataract surgery challenging. To date, several approaches have been developed. Implantation of a retropupillary iris-claw aphakic intraocular lens may be a good option because it is easier than suturing the IOL and can have better and more stable anatomic and visual outcomes, compared to other techniques. PMID:27350950

  7. Anterior mediastinal presentation of a giant angiomyolipoma.

    PubMed

    Amir, Afzal M I; Zeebregts, Clark J; Mulder, H Jan

    2004-12-01

    Angiomyolipomas are benign, solitary, noninvasive lesions that most often arise in the kidney. Extrarenal manifestations of these tumors include the skin, oropharynx, the abdominal wall, retroperitoneum, gastrointestinal tract, heart, lung, liver, uterus, penis, and spinal cord. We report a patient with a giant angiomyolipoma located in the anterior mediastinum. We believe this is the seventh reported case of mediastinal angiomyolipoma and the largest reported by size. It is the second reported lesion to arise in the anterior mediastinum. Distinction from other pulmonary or thoracic masses relies on the appreciation of the unique and characteristic histologic features of these mediastinal angiomyolipomas. We conclude that, although rare, angiomyolipoma should be considered in the differential diagnosis of a mediastinal tumor. PMID:15561061

  8. Anorgasmia in anterior spinal cord syndrome.

    PubMed Central

    Berić, A; Light, J K

    1993-01-01

    Three male and two female patients with anorgasmia and dissociated sensory loss due to an anterior spinal cord syndrome are described. Clinical, neurophysiological and quantitative sensory evaluation revealed preservation of the large fibre dorsal column functions from the lumbosacral segments with concomitant severe dysfunction or absence of the small fibre neospinothalamic mediated functions. These findings indicate a role for the spinothalamic system in orgasm. PMID:8505649

  9. Anorgasmia in anterior spinal cord syndrome.

    PubMed

    Berić, A; Light, J K

    1993-05-01

    Three male and two female patients with anorgasmia and dissociated sensory loss due to an anterior spinal cord syndrome are described. Clinical, neurophysiological and quantitative sensory evaluation revealed preservation of the large fibre dorsal column functions from the lumbosacral segments with concomitant severe dysfunction or absence of the small fibre neospinothalamic mediated functions. These findings indicate a role for the spinothalamic system in orgasm. PMID:8505649

  10. The Anterior Approach for Total Hip Replacement.

    PubMed

    Hochfelder, Jason P; Davidovitch, Roy I

    2016-03-01

    The anterior approach for total hip replacements has recently gained popularity. Some authors report faster recoveries and decreased dislocation rated with no increased risk of complications. However others claim no difference in outcomes when compared to other approaches yet an increase in complication rates. This paper provides a brief history of the approach, discusses various indications and contraindications, preoperative considerations, surgical techniques, and postoperative protocols. PMID:26977549

  11. Anterior cervical hypertrichosis and mental retardation.

    PubMed

    Thienpont, Bernard; Vermeesch, Joris; Devriendt, Koen

    2006-07-01

    Anterior cervical hypertrichosis or hairy throat is a rare dysmorphic sign described in a total of 19 patients so far. The association with a number of additional features has been reported, including mental retardation. We report on another patient with this condition who also had moderate mental retardation, mildly dysmorphic facial features, obesity, hypermetropia and additional hair anomalies (low dorsal hair line on the neck, lumbosacral hypertrichosis). Karyotype and array comparative genomic hybridization analysis at 1 Mb resolution were normal. PMID:16760744

  12. Glandular Odontogenic Cyst of the Anterior Mandible

    PubMed Central

    Raju, Srinivasa Pathapati; Reddy, Sridhar Padala; Ananthnag, Jakkula

    2015-01-01

    Context: Glandular odontogenic cyst (GOC) is a rare cyst occurring in the middle-age people with mandibular anterior as the common site of occurrence. Case Report: We report a case of massive GOC in a 65-year-old female with an emphasis on its clinical course, histological features, and treatment modalities. Conclusion: The aggressiveness and recurrences of GOC warrants clinicians for the careful examination, treatment, and long-term follow-up. PMID:25789251

  13. Cervical vertebral fusion with anterior meningocele

    PubMed Central

    Chavredakis, Emmanuel; Carter, David; Bhojak, Manesh; Jenkinson, Michael D; Clark, Simon R

    2015-01-01

    We present the first described case of cervical vertebral fusion associated with anterior meningocele and syringomyelia. A 45-year-old woman presented with minor trauma, and plain cervical spine radiographs highlighted a congenital deformity of the cervical vertebral bodies. She had a normal neurological examination; however, further imaging revealed a meningocele and syringomyelia. This case highlights the importance of thorough imaging investigation when presented with a congenital deformity in order to detect and prevent development of degenerative spinal cord pathologies. PMID:25923673

  14. Anterior segment dysgenesis in mosaic Turner syndrome

    PubMed Central

    Lloyd, I; Haigh, P; Clayton-Smith, J; Clayton, P; Price, D; Ridgway, A; Donnai, D

    1997-01-01

    AIMS/BACKGROUND—Females with Turner syndrome commonly exhibit ophthalmological abnormalities, although there is little information in the literature documenting findings specific to Turner syndrome mosaics. Ophthalmic findings are described in four patients with mosaic Turner syndrome. All had anterior chamber abnormalities and all four had karyotypic abnormalities with a 45, X cell line. The possible relation between the karyotypic and the phenotypic findings in these patients is discussed.
METHODS—Four girls with mosaic Turner syndrome underwent a full ophthalmological assessment, including examination under anaesthesia where indicated.
RESULTS—Three of the four patients presented with congenital glaucoma. Two had the karyotype 45, X/46, X, idic(Y) and one a 45, X/47, XXX karyotype. The remaining child had a Rieger malformation of the iris and the karyotype 45, X/46, X, r(X).
CONCLUSIONS—These findings suggest that Turner syndrome mosaicism (where there are two abnormal cell lines) is associated with anterior segment dysgenesis. The findings in these four patients are compared with those seen in other mosaic phenotypes and it is postulated that the presence of two or more genetically different cell lines may have an adverse effect on anterior segment development.

 PMID:9349149

  15. The thoracic anterior spinal cord adhesion syndrome

    PubMed Central

    Taylor, T R; Dineen, R; White, B; Jaspan, T

    2012-01-01

    Objectives This study included a series of middle-aged male and female patients who presented with chronic anterior hemicord dysfunction progressing to paraplegia. Imaging of anterior thoracic cord displacement by either a dural adhesion or a dural defect with associated cord herniation is presented. Methods This is a retrospective review of cases referred to a tertiary neuroscience centre over a 19-year period. Imaging series were classified by two experienced neuroradiologists against several criteria and correlated with clinical examination and/or findings at surgery. Results 16 cases were available for full review. Nine were considered to represent adhesions (four confirmed surgically) and four to represent true herniation (three confirmed surgically). In the three remaining cases the diagnosis was radiologically uncertain. Conclusion The authors propose “thoracic anterior spinal cord adhesion syndrome” as a novel term to describe this patient cohort and suggest appropriate clinicoradiological features for diagnosis. Several possible aetiologies are also suggested, with disc rupture and inflammation followed by disc resorption and dural pocket formation being a possible mechanism predisposing to herniation at the extreme end of a clinicopathological spectrum. PMID:22665931

  16. Magnetic dipole discharges. III. Instabilities

    SciTech Connect

    Stenzel, R. L.; Urrutia, J. M.; Ionita, C.; Schrittwieser, R.

    2013-08-15

    Instabilities in a cross-field discharge around a permanent magnet have been investigated. The permanent magnet serves as a cold cathode and the chamber wall as an anode. The magnet is biased strongly negative and emits secondary electrons due to impact of energetic ions. The electrons outside the sheath are confined by the strong dipolar magnetic field and by the ion-rich sheath surrounding the magnet. The electron energy peaks in the equatorial plane where most ionization occurs and the ions are trapped in a negative potential well. The discharge mechanism is the same as that of cylindrical and planar magnetrons, but here extended to a 3-D cathode geometry using a single dipole magnet. While the basic properties of the discharge are presented in a companion paper, the present focus is on various observed instabilities. The first is an ion sheath instability which oscillates the plasma potential outside the sheath below the ion plasma frequency. It arises in ion-rich sheaths with low electron supply, which is the case for low secondary emission yields. Sheath oscillations modulate the discharge current creating oscillating magnetic fields. The second instability is current-driven ion sound turbulence due to counter-streaming electrons and ions. The fluctuations have a broad spectrum and short correlation lengths in all directions. The third type of fluctuations is spiky potential and current oscillations in high density discharges. These appear to be due to unstable emission properties of the magnetron cathode.

  17. Selected instability indices in Europe

    NASA Astrophysics Data System (ADS)

    Siedlecki, Mariusz

    2009-04-01

    A climatology of various parameters associated with severe weather and convective storms has been created for Europe that involves using radiosounding data collected at the University of Wyoming for the period from 1991 to 2005. The analysis is based on monthly means, frequency distributions of such parameters as convective available potential energy (CAPE), convective inhibition energy (CIN), KI - index, total totals index (TTI), and the severe weather threat index (SWEAT). Monthly average CAPE values exceeding 300 Jkg-1 are observed over the west Mediterranean Sea and the neighboring coastal countries. The similar seasonal cycle and spatial distributions exhibit CIN fields with summer monthly means above 100 Jkg-1 observed on the south part of the researched domain. The KI, TTI, and SWEAT indices, which assess both the lapse ratio between 850 and 500 hPa and low level humidity, show the privileged region (the Alpine area and the Carpathian Basin) with the highest instability conditions. Orography clearly plays an important role in this structure. Farther from this area, the monthly average decreases to the east, west, north, and south of the research domain. Ward’s procedure was applied to create objective regionalization according to instability conditions. This method tends to produce two regions with relatively different instability conditions and few subregions with similar conditions. The first region, covering the Alpine area, the west Mediterranean Sea, west Turkey and the southern Ukraine, is characterized by the highest instability. The rest of the investigated area is the second region with a more stable atmosphere.

  18. 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.

  19. 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.

  20. 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.

  1. Functional Outcomes of Primary Anterior Cruciate Ligament Reconstruction with Tibialis Anterior Allograft

    PubMed Central

    Başar, Selda; Büyükafşar, Enes; Hazar, Zeynep; Ataoğlu, Baybars; Kanatlı, Ulunay

    2014-01-01

    Objectives: Allografts have potential advantages in primary anterior cruciate ligament reconstruction (ACLR), including the absence of donor site morbidity, shorter operative times, improved cosmesis, and easier rehabilitation. There is limited and conflicting outcome data for ACLR with tibialis anterior allograft. The purpose of this study was to evaluate the functional outcomes of ACLR with tibialis anterior allograft. Methods: We retrospectively evaluated patients underwent ACLR using with tibialis anterior allograft between 2005 and 2013. Totally 12 patients who were performed suspensory fixation technique were included in this study (range: 25-43 years). Exclusion criteria included double bundle, bone tendon bone technique and revision surgery. Clinical outcomes were measured by subject part of International Knee Documentation Committee (IKDC) and Lysholm scores. Results: A significant increase was reported in all the clinical scores. In particular, the IKDC-subjective score increased from a basal value of 45.5±12.7 to 84.3±5.50 at the 12 months' evaluation (p<0.05). The Lysholm score revealed a significant improvement from 49.7±14.2 to 83.5±20.5 at the 12 months' evaluation (p<0.05). Conclusion: ACLR with tibialis anterior allograft is an effective treatment for correcting loss of function and increasing quality of life.

  2. Large-Larmor-radius interchange instability

    SciTech Connect

    Ripin, B.H.; McLean, E.A.; Manka, C.K.; Pawley, C.; Stamper, J.A.; Peyser, T.A.; Mostovych, A.N.; Grun, J.; Hassam, A.B.; Huba, J.

    1987-11-16

    We observe linear and nonlinear features of a strong plasma/magnetic field interchange Rayleigh-Taylor instability in the limit of large ion Larmor radius. The instability undergoes rapid linear growth culminating in free-streaming flute tips.

  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. PMID:26395692

  6. Midcarpal Instability: A Comprehensive Review and Update.

    PubMed

    Niacaris, Timothy; Ming, Bryan W; Lichtman, David M

    2015-08-01

    Midcarpal instability has been well described as a clinical entity but the pathokinematics and pathologic anatomy continue to be poorly understood. This article presents a comprehensive review of the existing knowledge and literature-based evidence for the diagnosis and management of the various entities comprising midcarpal instability. It discusses the limitations of the current understanding of midcarpal instability and proposes new directions for furthering knowledge of the causes and treatment of midcarpal instability and wrist pathomechanics in general. PMID:26205710

  7. Measurements of fast transition instability in RHIC

    SciTech Connect

    Ptitsyn, V.; Blaskiewicz, M.; Fischer, W.; Lee, R.; Zhang, S.Y.

    2010-05-23

    A fast transition instability presents a limiting factor for ion beam intensity in RHIC. Several pieces of evidence show that electron clouds play an important role in establishing the threshold of this instability. In RHIC Runs8 the measurements of the instability, using a button BPM, were done in order to observe details of the instability development on the scale over hundreds and thousands turns. The paper presents and discusses the results of those measurements in time and frequency domains.

  8. Medical restraints to anterior-posterior motion of the knee.

    PubMed

    Sullivan, D; Levy, I M; Sheskier, S; Torzilli, P A; Warren, R F

    1984-07-01

    We investigated the motion of cadaver knees before and after section of the medial structures and anterior cruciate ligament. The knees were tested using a 5-degrees-of-freedom in vitro knee-testing apparatus that measured anterior-posterior, medial-lateral, and axial displacement as well as internal-external and valgus-varus rotation. The flexion angle could be varied but was fixed for each individual test. A 125-newton anterior-posterior force was applied perpendicular to the tibial shaft and the resulting motion of the knee was measured. In five knees the anterior cruciate ligament was cut first, followed by progressive cuts of the structures on the medial side (superficial medial collateral ligament, deep medial ligament, oblique fibers of the superficial medial ligament, and the posteromedial part of the capsule). Conversely, in five knees the medial structures were progressively cut first, followed by section of the anterior cruciate ligament. Tests were performed after each cut. With an intact anterior cruciate ligament, progressive cutting of the medial side had no effect on anterior and posterior displacements. When section of the medial structures followed cutting of the anterior cruciate ligament, anterior displacement exceeded that seen after isolated section of the anterior cruciate ligament. The anterior and posterior load-tests were repeated with the tibia fixed in 5 degrees of internal and 5 degrees of external rotation. Fixed external rotation had no effect on anterior and posterior displacements. Fixed internal rotation significantly decreased anterior displacement only when both the anterior cruciate ligament and the medial structures were cut.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:6736094

  9. 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

  10. 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.

  11. Basic instabilities of collisionless gravitating systems.

    NASA Astrophysics Data System (ADS)

    Polyachenko, V. L.

    1995-05-01

    The paper presents a short summary of basic instabilities in stellar systems, namely: the Jeans, bar-mode and fire-hose (bending) instabilities. A classification of bar-mode instabilities according to a ratio of the bar pattern angular velocity and the maximal precession speed of nearly-circular stellar orbits is proposed.

  12. 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.

  13. Solitons versus parametric instabilities during ionospheric heating

    NASA Technical Reports Server (NTRS)

    Nicholson, D. R.; Payne, G. L.; Downie, R. M.; Sheerin, J. P.

    1984-01-01

    Various effects associated with ionospheric heating are investigated by numerically solving the modified Zakharov (1972) equations. It is shown that, for typical ionospheric parameters, the modulational instability is more important than the parametric decay instability in the spatial region of strongest heater electric field. It is concluded that the modulational instability leads to the formation of solitons, as originally predicted by Petviashvili (1976).

  14. Control of laser plasma instabilities in hohlraums

    SciTech Connect

    Kruer, W.L.

    1996-12-01

    Laser plasma instabilities are an important constraint on the operating regime for inertial fusion. Many techniques have been developed to control the various laser-driven instabilities. Experiments with long scale length plasmas are testing these instability levels, the nonlinear regimes, and the control mechanisms.

  15. An anterior signaling center patterns and sizes the anterior neuroectoderm of the sea urchin embryo.

    PubMed

    Range, Ryan C; Wei, Zheng

    2016-05-01

    Anterior signaling centers help specify and pattern the early anterior neuroectoderm (ANE) in many deuterostomes. In sea urchin the ANE is restricted to the anterior of the late blastula stage embryo, where it forms a simple neural territory comprising several types of neurons as well as the apical tuft. Here, we show that during early development, the sea urchin ANE territory separates into inner and outer regulatory domains that express the cardinal ANE transcriptional regulators FoxQ2 and Six3, respectively. FoxQ2 drives this patterning process, which is required to eliminate six3 expression from the inner domain and activate the expression of Dkk3 and sFRP1/5, two secreted Wnt modulators. Dkk3 and low expression levels of sFRP1/5 act additively to potentiate the Wnt/JNK signaling pathway governing the positioning of the ANE territory around the anterior pole, whereas high expression levels of sFRP1/5 antagonize Wnt/JNK signaling. sFRP1/5 and Dkk3 levels are rigidly maintained via autorepressive and cross-repressive interactions with Wnt signaling components and additional ANE transcription factors. Together, these data support a model in which FoxQ2 initiates an anterior patterning center that implements correct size and positions of ANE structures. Comparisons of functional and expression studies in sea urchin, hemichordate and chordate embryos reveal striking similarities among deuterostome ANE regulatory networks and the molecular mechanism that positions and defines ANE borders. These data strongly support the idea that the sea urchin embryo uses an ancient anterior patterning system that was present in the common ambulacrarian/chordate ancestor. PMID:26952978

  16. 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

  17. Generalized laser filamentation instability coupled to cooling instability

    SciTech Connect

    Liang, E.P.; Wong, J.; Garrison, J.

    1984-04-24

    We consider the propagation of laser light in an initially slightly nonuniform plasma. The classical dispersion relation for the laser filamentation growth rate (see e.g., B. Langdon, in the 1980 Lawrence Livermore National Laboratory Laser Program Annual Report, pp. 3-56, UCRL-50021-80, 1981) can be generalized to include other acoustical effects. For example, we find that the inclusion of potential imbalances in the heating and cooling rates of the ambient medium due to density and temperature perturbations can cause the laser filamentation mode to bifurcate into a cooling instability mode at long acoustic wavelengths. We also attempt to study semi-analytically the nonlinear evolution of this and related instabilities. These results have wide applications to a variety of chemical gas lasers and phenomena related to laser-target interactions (e.g., jet-like behavior).

  18. Injury to the Anterior Tibial Artery during Bicortical Tibial Drilling in Anterior Cruciate Ligament Reconstruction

    PubMed Central

    Kim, Sang Bum; Lim, Jin Woo; Seo, Jeong Gook

    2016-01-01

    Many complications have been reported during or after anterior cruciate ligament (ACL) reconstruction, including infection, bleeding, tibial tunnel widening, arthrofibrosis, and graft failure. However, arterial injury has been rarely reported. This paper reports a case of an anterior tibial arterial injury during bicortical tibial drilling in arthroscopic ACL reconstruction, associated with an asymptomatic occlusion of the popliteal artery. The patient had a vague pain which led to delayed diagnosis of compartment syndrome and delayed treatment with fasciotomy. All surgeons should be aware of these rare but critical complications because the results may be disastrous like muscle necrosis as in this case. PMID:26929808

  19. Injury to the Anterior Tibial Artery during Bicortical Tibial Drilling in Anterior Cruciate Ligament Reconstruction.

    PubMed

    Kim, Sang Bum; Lim, Jin Woo; Seo, Jeong Gook; Ha, Jeong Ku

    2016-03-01

    Many complications have been reported during or after anterior cruciate ligament (ACL) reconstruction, including infection, bleeding, tibial tunnel widening, arthrofibrosis, and graft failure. However, arterial injury has been rarely reported. This paper reports a case of an anterior tibial arterial injury during bicortical tibial drilling in arthroscopic ACL reconstruction, associated with an asymptomatic occlusion of the popliteal artery. The patient had a vague pain which led to delayed diagnosis of compartment syndrome and delayed treatment with fasciotomy. All surgeons should be aware of these rare but critical complications because the results may be disastrous like muscle necrosis as in this case. PMID:26929808

  20. Weber B Fracture of the Lateral Malleolus with Concomitant Anterior Talofibular Ligament Injury following an Ankle Supination Injury.

    PubMed

    Faqi, Mohammed Khalid; AlJawder, Abdulla; Alkhalifa, Fahad; Almajed, Ali H

    2016-01-01

    The Lauge-Hansen (LH) classification attempts to predict patterns of ankle injuries based upon the preceding mechanism of injury. Although it is widely used in clinical practice, it has been criticized mainly due to numerous reports of cases conflicting the prediction system. Here, we report a case of a 32-year-old male who sustained a Weber B fracture of the lateral malleolus following a supination ankle injury, which was treated conservatively, following which the patient presented with ankle instability and was found to have concurrent anterior talofibular ligament tear. Critical review of the LH classification along with its shortcomings is discussed. PMID:27313928

  1. Weber B Fracture of the Lateral Malleolus with Concomitant Anterior Talofibular Ligament Injury following an Ankle Supination Injury

    PubMed Central

    AlJawder, Abdulla; Almajed, Ali H.

    2016-01-01

    The Lauge-Hansen (LH) classification attempts to predict patterns of ankle injuries based upon the preceding mechanism of injury. Although it is widely used in clinical practice, it has been criticized mainly due to numerous reports of cases conflicting the prediction system. Here, we report a case of a 32-year-old male who sustained a Weber B fracture of the lateral malleolus following a supination ankle injury, which was treated conservatively, following which the patient presented with ankle instability and was found to have concurrent anterior talofibular ligament tear. Critical review of the LH classification along with its shortcomings is discussed. PMID:27313928

  2. 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

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

    NASA Astrophysics Data System (ADS)

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

    2016-03-01

    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.

  4. Effects of balance training by knee joint motions on muscle activity in adult men with functional ankle instability

    PubMed Central

    Nam, Seung-min; Kim, Won-bok; Yun, Chang-kyo

    2016-01-01

    [Purpose] This study examined the effects of balance training by applying knee joint movements on muscle activity in male adults with functional ankle instability. [Subjects and Methods] 28 adults with functional ankle instability, divided randomly into an experimental group, which performed balance training by applying knee joint movements for 20 minutes and ankle joint exercises for 10 minutes, and a control group, which performed ankle joint exercise for 30 minutes. Exercises were completed three times a week for 8 weeks. Electromyographic values of the tibialis anterior, peroneus longus, peroneus brevis, and the lateral gastrocnemius muscles were obtained to compare and analyze muscle activity before and after the experiments in each group. [Results] The experimental group had significant increases in muscle activity in the tibialis anterior, peroneus longus, and lateral gastrocnemius muscles, while muscle activity in the peroneus brevis increased without significance. The control group had significant increases in muscle activity in the tibialis anterior and peroneus longus, while muscle activity in the peroneus brevis and lateral gastrocnemius muscles increased without significance. [Conclusion] In conclusion, balance training by applying knee joint movements can be recommended as a treatment method for patients with functional ankle instability. PMID:27313386

  5. Mechanical Joint Laxity Associated With Chronic Ankle Instability

    PubMed Central

    Cordova, Mitchell L.; Sefton, JoEllen M.; Hubbard, Tricia J.

    2010-01-01

    Context: Lateral ankle sprains can manifest into chronic mechanical joint laxity when not treated effectively. Joint laxity is often measured through the use of manual stress tests, stress radiography, and instrumented ankle arthrometers. Purpose: To systematically review the literature to establish the influence of chronic ankle instability (CAI) on sagittal and frontal plane mechanical joint laxity. Data Sources: Articles were searched with MEDLINE (1966 to October 2008), CINAHL (1982 to October 2008), and the Cochrane Database of Systematic Reviews (to October 2008) using the key words chronic ankle instability and joint laxity, functional ankle instability and joint laxity, and lateral ankle sprains and joint laxity. Study Selection: To be included, studies had to employ a case control design; mechanical joint laxity had to be measured via a stress roentogram, an instrumented ankle arthrometer, or ankle/foot stress-testing device; anteroposterior inversion or eversion ankle-subtalar joint complex laxity had to be measured; and means and standard deviations of CAI and control groups had to be provided. Data Extraction: One investigator assessed each study based on the criteria to ensure its suitability for analysis. The initial search yielded 1378 potentially relevant articles, from which 8 were used in the final analysis. Once the study was accepted for inclusion, its quality was assessed with the PEDro scale. Data Synthesis: Twenty-one standardized effect sizes and their 95% confidence intervals were computed for each group and dependent variable. CAI produced the largest effect on inversion joint laxity; 45% of the effects ranged from 0.84 to 2.61. Anterior joint laxity measures were influenced second most by CAI (effects, 0.32 to 1.82). CAI had similar but less influence on posterior joint laxity (effects, −0.06 to 0.68) and eversion joint laxity (effects, 0.03 to 0.69). Conclusion: CAI has the largest effect with the most variability on anterior and

  6. Knee imaging after anterior cruciate ligament reconstruction.

    PubMed

    Rodrigues, M B; Silva, J J; Homsi, C; Stump, X M; Lecouvet, F E

    2001-01-01

    An increasing number of reconstructions of the anterior cruciate ligament (ACL) are performed every year, due to both the increasing occurrence of sport related injuries and the development of diagnostic and surgical techniques. The most used surgical procedure for the torn ACL reconstruction is the use of autogenous material, most often the patellar and semitendinosus tendons. Magnetic resonance (MR) imaging and spiral-CT performed after arthrography with multiplanar reconstructions are the imaging methods of choice for post-operative evaluation of ACL ligamentoplasty. This paper provides a brief bibliographic and more extensive pictorial review of the normal evolution and possible complications after ACL repair. PMID:11817479

  7. Ultrasound of the male anterior urethra

    PubMed Central

    Shaida, N; Berman, L H

    2012-01-01

    Imaging of the anterior male urethra has traditionally been performed by fluoroscopic contrast urethrography. While providing easily interpretable images, this technique has a number of disadvantages associated with it. An alternative approach is to use ultrasound to assess the lumen of the urethra and the periurethral tissues. Here we describe the development of urethral ultrasound and the ascending and descending urethral ultrasound techniques employed in our institution with reference to commonly and uncommonly encountered pathologies. We also identify common pitfalls and how to avoid them. PMID:22674713

  8. [Perineal urethrostomy in complex anterior urethral stricture].

    PubMed

    Barbagli, G

    2010-06-01

    Staged urethroplasty is a well-known procedure for urethral reconstruction that had already been described by Russell in 1914 and was later popularized by Johanson, Turner-Warwick, Blandy, and Schreiter. It lends itself to the treatment of complex anterior urethral stricture in combination with lichen sclerosus, failed correction of hypospadias, fistula, via falsa, abscess, carcinoma, or previously unsuccessful urethroplasty. Perineal urethrostomy can be performed as a temporary or definitive measure. Some patients even decline further urethral reconstruction because they perceive subjective satisfaction after perineal urethrostomy that was originally intended to be temporary. PMID:20544335

  9. 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.

  10. New Instabilities in Line Driven Winds

    NASA Technical Reports Server (NTRS)

    Martens, P. C. H.

    1985-01-01

    The physical mechanisms which potentially lead to instabilities in line driven winds, the drift instability and the line shape instability, are discussed. A general three dimensional treatment of the stability problem of line driven winds which leads to the general dispersion equation is proposed. From this dispersion equation automatically a third physical mechanism driving instability in stellar winds is deduced; the thermal drift instability which is related to changes in absorption of radiation caused by temperature perturbations. This mechanism results in growing inwardly propagating sound waves.

  11. 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.

  12. 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.

  13. MHD Instabilities at the Heliopause

    SciTech Connect

    Dasgupta, B.; Florinski, V.; Heerikhuisen, J.; Zank, G. P.

    2006-09-26

    The heliopause (HP) is the outer edge of the heliosphere which separates the tenuous and hot heliosheath plasma on one side and the relatively dense and cool magnetized interstellar plasma on the other side. As a surface of tangential discontinuity, the HP is subjected to both Rayleigh-Taylor (RT) and Kelvin-Helmholtz (KH) instabilities. The coupling between plasma ions and neutral atoms through the process of charge exchange provides an ''effective gravity'' at the HP, while a shear flow exists across it. We derive analytically the linearized dispersion relation for waves propagating along the surface of this discontinuity, which represents a combined RT/KH analysis. We investigate both the purely hydrodynamic, as well as magnetohydrodynamic, cases, and find that interstellar and heliospheric magnetic fields can help stabilize the HP for RT and KH-type instabilities.

  14. Nonlinear evolution of Buneman instability

    NASA Astrophysics Data System (ADS)

    Ishihara, O.; Hirose, A.; Langdon, A. B.

    1981-03-01

    The nonlinear evolution of one-dimensional electron-ion two-stream instability in a field-free plasma is investigated analytically and by computer simulation. The instability is dominated by the fastest growing mode and its harmonics, provided that the initial fluctuation level is sufficiently small. A nonlinear dispersion relation is obtained and solved numerically, with allowance for the frequency and growth rate modulation, the electric field up to a specified order, and the renormalized particle distribution functions. It is shown that the model can explain computer simulation results, including the presence of an algebraic growth stage following the breakdown of the exponential linear growth, the appearance of harmonics, and the final saturation level.

  15. Feedback control of resistive instabilities

    SciTech Connect

    White, R.B.; Rutherford, P.H.; Furth, H.P.; Park, W.; Chen, L.

    1985-12-01

    Resistive instabilities are responsible for much of the global behavior and the determination of the possible domains of operation of tokamaks. Their successful control could have definite advantages, even making available new regimes of operation. Elimination of sawtoothing might allow operation with higher currents and more peaked current profiles, with q on axis well below unity. In this work different feedback schemes are explored. Simple analytical derivations of the effects of local heating and current drive feedback are presented. Although control of modes with m greater than or equal to 2 is fairly straightforward, the control of the m = 1 mode is more difficult because of its proximity to ideal instability. The most promising scheme utilizes high energy trapped particles. 20 refs., 3 figs.

  16. 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.

  17. A cosmic ray driven instability

    NASA Technical Reports Server (NTRS)

    Dorfi, E. A.; Drury, L. O.

    1985-01-01

    The interaction between energetic charged particles and thermal plasma which forms the basis of diffusive shock acceleration leads also to interesting dynamical phenomena. For a compressional mode propagating in a system with homogeneous energetic particle pressure it is well known that friction with the energetic particles leads to damping. The linear theory of this effect has been analyzed in detail by Ptuskin. Not so obvious is that a non-uniform energetic particle pressure can addition amplify compressional disturbances. If the pressure gradient is sufficiently steep this growth can dominate the frictional damping and lead to an instability. It is important to not that this effect results from the collective nature of the interaction between the energetic particles and the gas and is not connected with the Parker instability, nor with the resonant amplification of Alfven waves.

  18. Polygonal instabilities on interfacial vorticities.

    PubMed

    Labousse, M; Bush, J W M

    2015-10-01

    We report the results of a theoretical investigation of the stability of a toroidal vortex bound by an interface. Two distinct instability mechanisms are identified that rely on, respectively, surface tension and fluid inertia, either of which may prompt the transformation from a circular to a polygonal torus. Our results are discussed in the context of three experiments, a toroidal vortex ring, the hydraulic jump, and the hydraulic bump. PMID:26537726

  19. 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.

  20. 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.

  1. 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. PMID:26824573

  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. 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.

  4. Anterior segment spectral domain optical coherence tomography imaging of patients with anterior scleritis.

    PubMed

    Levison, Ashleigh L; Lowder, Careen Y; Baynes, Kimberly M; Kaiser, Peter K; Srivastava, Sunil K

    2016-08-01

    The purpose of the study was to describe the findings seen on anterior segment spectral domain optical coherence tomography (SD-OCT) in patients with anterior scleritis and determine the feasibility of using SD-OCT to image and grade the degree of scleral inflammation and monitor response to treatment. All patients underwent slit lamp examination by a uveitis specialist, and the degree of scleral inflammation was recorded. Spectral domain OCT imaging was then performed of the conjunctiva and scleral tissue using a standardized acquisition protocol. The scans were graded and compared to clinical findings. Twenty-eight patients with anterior scleritis and ten patients without ocular disease were included in the study. Seventeen of the scleritis patients were followed longitudinally. Common findings on SD-OCT in patients with active scleritis included changes in hyporeflectivity within the sclera, nodules, and visible vessels within the sclera. There was significant variation in findings on SD-OCT within each clinical grade of active scleritis. These changes on SD-OCT improved with treatment and clinical improvement. SD-OCT imaging provided various objective measures that could be used in the future to grade inflammatory activity in patients with anterior scleritis. Longitudinal imaging of patients with active scleritis demonstrated that SD-OCT may have great utility in monitoring response to treatment. PMID:26597942

  5. INFLUENCE OF ANTERIOR PAIN ON RESULTS FROM ANTERIOR CRUCIATE LIGAMENT RECONSTRUCTION

    PubMed Central

    Vasconcelos, Wilson; Santos, Claudinei; Ferracini, Antonio Marcos; Dejour, David

    2015-01-01

    Objective: To examine the impact of residual pain on functional outcomes two years after arthroscopic anterior cruciate ligament (ACL) reconstruction and compare the types of graft used during the procedure (patellar vs. flexor). Method: A retrospective epidemiological study on 129 ACL reconstructions with a mean follow-up of 28 months was conducted. The presence, intensity and location of the anterior pain were investigated. Pain provocation tests were conducted, sensitivity was analyzed and functional scores were applied (IKDC, femoropatellar and SF-36), comparing the results with the type of graft used. Results: Anterior pain was present in 28% of patients with a mean intensity of 2.9 in 10. When pain was present, the functional scores decreased significantly. Abnormalities of knee sensitivity and gait occurred frequently with use of the patellar tendon, but there was no statistical difference regarding the presence of pain. Conclusion: The presence of anterior pain in ACL reconstructions, even if minimal, has a deleterious effect on the final outcome over the medium term. Because of the influence of graft harvesting on the presence of abnormalities of knee sensitivity and gait, choosing the graft should take into account the patient's professional and sports activities. PMID:27026984

  6. The mouse olfactory peduncle. 2.The anterior limb of the anterior commissure

    PubMed Central

    Brunjes, Peter C.

    2013-01-01

    The central core of the olfactory peduncle [the tissue connecting the olfactory bulb (OB) to the forebrain] includes a white matter tract that extends caudally to the anterior commissure (AC). The purpose of the present study was to examine this “anterior limb of the anterior commissure” (ALAC) to determine if the axons that progress through it segregate on the basis of their point of origin, neurotransmitter type, size, or shape. While local differences in axon density were observed in the ALAC, they were not consistent between samples of the anterior and posterior peduncle, and no other compartmentalization within the tract was observed. The innervation of the caudal olfactory peduncle by neuromodulatory fibers was examined to determine if they enter the region via the ALAC. Cholinergic fibers (CHAT) densely filled the peduncle, followed in order by serotonergic, noradrenergic, histaminergic, and orexinergic processes. Differences in the distribution of the fibers were noted for each system. While each axon type could be observed in the ALAC, it is probable that they enter the peduncle though several routes. Data for axon caliber in the ALAC was compared to information previously collected on the peduncle's other white matter region, the lateral olfactory tract (LOT). Axons in the ALAC were smaller, suggesting that the olfactory system is organized with a fast system for distributing incoming sensory information and a more economical, distributed system for subsequent processing. PMID:23355812

  7. Anterior debridement and bone grafting of spinal tuberculosis with one-stage instrumentation anteriorly or posteriorly

    PubMed Central

    Lian, Xiao Feng; Hou, Tie Sheng; Ma, Hui; Chen, Zhi Ming

    2006-01-01

    Between 2000 and 2004, 40 cases (average age 38, range 16–65 years) of spinal tuberculosis were treated with anterior debridement and iliac bone graft with one-stage anterior or posterior instrumentation in our unit. All patients received at least 2 weeks of regular antituberculous chemotherapy before surgery. We followed up all patients for 12–48 months (mean 22 months). Local symptoms of all patients were relieved significantly 1–3 weeks postoperatively; 23 of 25 cases (92%) with neurogical deficit had excellent or good clinical results. Erythrocyte sedimentation rates (ESR) returned from 51 mm/h to 32 mm/h (average) two weeks postoperatively. Kyphosis degrees were corrected by a mean of 16°. Fusion rate of the grafting bone was 72.5% one year postoperatively and 90% two years postoperatively. Severe complications did not occur. We therefore believe that patients undergoing anterior debridement and iliac bone grafting with one-stage anterior or posterior instrumentation achieve satisfactory clinical and radiographic outcomes. PMID:17061127

  8. Anterior vitrectomy and partial capsulectomy via anterior approach to treat chronic postoperative endophthalmitis

    PubMed Central

    Güler, Mete; Yılmaz, Turgut

    2013-01-01

    AIM To describe the results of vitrectomy and partial capsulectomy via anterior approach surgical technique in treatment of chronic postoperative endophthalmitis (CPE). METHODS Clinical records of 9 patients treated for CPE between 2006 and 2010 were reviewed retrospectively. All of these patients were treated with vitrectomy and partial capsulectomy via anterior approach. RESULTS Six of 9 patients were male. The average patients' age was (60±8.1) years. The average period between cataract extraction and onset of signs and symptoms was (3.6±1.3) weeks. The average presenting visual acuity was 0.3±0.1 and the average final post operative visual acuity was 0.7±0.2. The mean follow-up period was (28.1±8.9) weeks. In all patients, the inflammation subsided after surgery. CONCLUSION Our results suggest that anterior vitrectomy and partial capsulectomy via anterior approach may be considered as potentially useful and relatively less invasive technique to treat CPE. PMID:23550103

  9. 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.

  10. Bilateral Medial Tibial Plateau Fracture after Arthroscopic Anterior Cruciate Ligament Reconstruction

    PubMed Central

    Cho, Chul Hyun; Lee, Kyung Jae; Jeon, Jong Hyuk

    2015-01-01

    Tibial plateau fractures after arthroscopic anterior cruciate ligament (ACL) reconstruction are rare, and only isolated cases have been reported. The authors describe a case of bilateral medial tibial plateau fracture following a minor motorcycle accident in a patient who underwent arthroscopic ACL reconstruction in the past. Two years and four months before the accident, the patient underwent an arthroscopically assisted ACL reconstruction using double-bundle technique on his left knee at a hospital. He had the same surgery using single-bundle technique on his right knee about eight months ago at another hospital. The fractures in his both involved knees occurred through the tibial tunnel and required open reduction with internal fixation. At three weeks after fixation, a second-look arthroscopy revealed intact ACLs in both knees. At five months follow-up, he was able to walk without instability on physical examination. Follow-up radiographs of the patient showed callus formations with healed fractures. PMID:26060613

  11. Surgical Treatment of a Rare Isolated Bilateral Agenesis of Anterior and Posterior Cruciate Ligaments

    PubMed Central

    2014-01-01

    The isolated bilateral agenesis of both cruciate ligaments is a rare congenital disorder. A 17-year-old male came to our attention due to an alteration in gait pattern, pain, and tendency to walk on the forefoot with his knee flexed. The patient did not recall previous injuries. Upon physical examination anterior and posterior chronic instability were observed. Radiographic examination of both knees showed hypoplasia of the tibial eminence, a hypoplastic lateral femoral condyle, and a narrow intercondylar notch. MRI brought to light a bilateral agenesis of both posterior cruciate ligaments. Arthroscopic evaluation confirmed bilateral isolated agenesis of both cruciate ligaments. We recommended a rehabilitation program to prepare the patient for the arthroscopic construction of both cruciate ligaments. PMID:25197599

  12. Anterolateral Ligament of the Knee: Back to the Future in Anterior Cruciate Ligament Reconstruction

    PubMed Central

    Bonasia, Davide Edoardo; D’Amelio, Andrea; Pellegrino, Pietro; Rosso, Federica; Rossi, Roberto

    2015-01-01

    Although the importance of the anterolateral stabilizing structures of the knee in the setting of anterior cruciate ligament (ACL) injuries has been recognized since many years, most of orthopedic surgeons do not take into consideration the anterolateral structures when performing an ACL reconstruction. Anatomic single or double bundle ACL reconstruction will improve knee stability, but a small subset of patients may experience some residual anteroposterior and rotational instability. For this reason, some researchers have turned again towards the anterolateral aspect of the knee and specifically the anterolateral ligament. The goal of this review is to summarize the existing knowledge regarding the anterolateral ligament of the knee, including anatomy, histology, biomechanics and imaging. In addition, the most common anterolateral reconstruction/tenodesis techniques are described together with their respective clinical outcomes. PMID:26330991

  13. Dynamic neuromuscular analysis training for preventing anterior cruciate ligament injury in female athletes.

    PubMed

    Hewett, Timothy E; Myer, Gregory D; Ford, Kevin R; Slauterbeck, James R

    2007-01-01

    Female athletes are four to six times more likely to sustain an anterior cruciate ligament (ACL) injury than male athletes. Since the enactment of Title IX, male athletic participation at the high school level has remained steady (3.8 million), whereas female athletic participation has increased tenfold (from 0.3 to 3.0 million). Geometric growth in athletic participation and the higher injury rate in female athletes have led to gender inequity in ACL injury rates. Most ACL injuries occur as a result of noncontact mechanisms such as during landing from a jump or while making a lateral pivot. Dynamic knee instability, caused by ligament dominance (decreased dynamic neuromuscular control of the joint), quadriceps dominance (decreased hamstring strength and recruitment), and leg dominance (side-to-side differences in strength and coordination) may be responsible for gender inequity in ACL injury rates. PMID:17472323

  14. Differences among mechanoreceptors in healthy and injured anterior cruciate ligaments and their clinical importance

    PubMed Central

    Dhillon, Mandeep Sing; Bali, Kamal; Prabhakar, Sharad

    2012-01-01

    Summary Mechanoreceptors in an intact Anterior Cruciate Ligament (ACL) contribute towards functional stability of the knee joint. Injury to the ACL not only causes mechanical instability, but also leads to a disturbance in the neuromuscular control of the injured knee due to loss or damage to mechanoreceptors. ACL reconstruction restores proprioceptive potential of the knee to some extent, but the results vary. Although the remnant ACL contains residual mechanoreceptors, the number and functionality of these receptors is dependent, to some extent, on the physical characteristics of the remnant and duration of injury. Remnants, especially that adherent to the PCL, may actually act as a possible source of reinnervation of the graft. These remnants are worth preserving during ACL reconstruction and can play an important role in restoration of proprioception of knee following ACL reconstruction. PMID:23738272

  15. Disadvantages and advantages of transtibial technique for creating the anterior cruciate ligament femoral socket.

    PubMed

    Robin, Brett N; Lubowitz, James H

    2014-10-01

    Anterior cruciate ligament (ACL) femoral socket techniques have distinct advantages and disadvantages when considering the following techniques: transtibial, anteromedial portal, outside-in, and outside-in retroconstruction. There is no one perfect technique and we have an incomplete understanding of anatomical, biomechanical, isometry, stability, and clinical outcomes. Our primary focus is transtibial technique for creating the ACL femoral socket. Advantages include less invasive, isometric graft placement, stable Lachman exam, and minimal graft impingement with the tunnel and notch. Disadvantages include nonanatomic vertical graft placement that can cause rotational instability and positive pivot shift, interference screw divergence, graft-tunnel length mismatch, femoral socket constraint, posterior cruciate ligament impingement, and a short, oblique tibial tunnel that may undermine the medial plateau in an attempt to achieve anatomic ACL reconstruction. PMID:24951951

  16. Extranodal large B cell lymphoma of the anterior maxilla. Case report and review of literature.

    PubMed

    Webber, Brian; Webber, Mariel; Keinan, David

    2015-01-01

    In the oral cavity, lymphoproliferative disorders can manifest in various ways, often as an extranodal externalization. In the case presented here, it was a B cell lymphoma originating in the periapical bone of the anterior maxilla. X-ray revealed a periapical radiolucency associated with an intact tooth with no decay, fillings or history of trauma. The tooth tested non-vital. After root canal treatment, an apicoectomy was performed with a biopsy. The most common diagnosis would be of dental etiology. The pathology report revealed a non-Hodgkin's B cell lymphoma. Most often, this disease appears as localized dental or oral pathology. Non-specific signs and symptoms present in association with lymphoproliferative disorders include lymphadenopathy, trismus, pain, swelling, sinusitis, fever, sepsis, prosthetic instability and paresthesia. Early detection results in decreased morbidity and a better prognosis for the patient. PMID:25707167

  17. Lesion-negative anterior cingulate epilepsy.

    PubMed

    Lacuey, Nuria; Davila, Javier Chapa; Zonjy, Bilal; Amina, Shahram; Couce, Marta; Turnbull, John; Miller, Jonathan; Lüders, Hans; Lhatoo, Samden D

    2015-06-01

    MRI-negative anterior cingulate epilepsy is a rare entity. Herein, we describe a case of MRI and functional imaging-negative intractable frontal lobe epilepsy in which, initially, secondary bilateral synchrony of surface and intracranial EEG and non-lateralizing semiology rendered identification of the epileptogenic zone difficult. A staged bilateral stereotactic EEG exploration revealed a very focal, putative ictal onset zone in the right anterior cingulate gyrus, as evidenced by interictal and ictal high-frequency oscillations (at 250Hz) and induction of seizures from the same electrode contacts by 50-Hz low-intensity cortical stimulation. This was subsequently confirmed by ILAE class 1 outcome following resection of the ictal onset and irritative zones. Histopathological examination revealed focal cortical dysplasia type 1b (ILAE Commission, 2011) as the cause of epilepsy. The importance of anatomo-electro-clinical correlation is illustrated in this case in which semiological and electrophysiological features pointed to the anatomical localization of a challenging, MRI-negative epilepsy. PMID:26056053

  18. Geometry of anterior open bite correction.

    PubMed

    Abramson, Zachary R; Susarla, Srinivas M; Lawler, Matthew E; Choudhri, Asim F; Peacock, Zachary S

    2015-05-01

    Correction of anterior open bite is a frequently encountered and challenging problem for the craniomaxillofacial surgeon and orthodontist. Accurate clinical evaluation, including cephalometric assessment, is paramount for establishing the diagnosis and appropriate treatment plan. The purposes of this technical note were to discuss the basic geometric principles involved in the surgical correction of skeletal anterior open bites and to offer a simple mathematical model for predicting the amount of posterior maxillary impaction with concomitant mandibular rotation required to establish an adequate overbite. Using standard geometric principles, a mathematical model was created to demonstrate the relationship between the magnitude of the open bite and the magnitude of the rotational movements required for correction. This model was then validated using a clinical case. In summary, the amount of open bite closure for a given amount of posterior maxillary impaction depends on anatomic variables, which can be obtained from a lateral cephalogram. The clinical implication of this relationship is as follows: patients with small mandibles and steep mandibular occlusal planes will require greater amounts of posterior impaction. PMID:25950521

  19. Anterior Hepatic Transection for Caudate Lobectomy

    PubMed Central

    Chaib, Eleazar; Ribeiro, Marcelo A F; de Souza, Yngrid Ellyn Dias Maciel; D’Albuquerque, Luiz Augusto C

    2009-01-01

    Resection of the caudate lobe (segment I- dorsal sector, segment IX- right paracaval region, or both) is often technically difficult due to the lobe’s location deep in the hepatic parenchyma and because it is adjacent to the major hepatic vessels (e.g., the left and middle hepatic veins). A literature search was conducted using Ovid MEDLINE for the terms “caudate lobectomy” and “anterior hepatic transection” (AHT) covering 1992 to 2007. AHT was used in 110 caudate lobectomies that are discussed in this review. Isolated caudate lobectomy was performed on 28 (25.4%) patients, with 11 case (11%) associated with hepatectomy, while 1 (0.9%) was associated with anterior segmentectomy. Complete caudate lobectomy was performed on 82 (74.5%) patients. Hepatocellular carcinoma was observed in 106 (96.3%) patients, while 1 (0.9%) had hemangioma and 3 (2.7%) had metastatic caudate tumors. AHT was used in 108 (98.1%) caudate resections, while AHT associated with a right-sided approach was performed in 2 (1.8%) cases. AHT is recommended for tumors located in the paracaval portion of the caudate lobe (segment IX). AHT is usually a safe and potentially curative surgical option. PMID:19936187

  20. Adjacent Segment Pathology after Anterior Cervical Fusion

    PubMed Central

    Chung, Jae Yoon; Park, Jong-Beom; Seo, Hyoung-Yeon

    2016-01-01

    Anterior cervical fusion has become a standard of care for numerous pathologic conditions of the cervical spine. However, subsequent development of clinically significant disc disease at levels adjacent to fused discs is a serious long-term complication of this procedure. As more patients live longer after surgery, it is foreseeable that adjacent segment pathology (ASP) will develop in increasing numbers of patients. Also, ASP has been studied more intensively with the recent popularity of motion preservation technologies like total disc arthroplasty. The true nature and scope of ASP remains poorly understood. The etiology of ASP is most likely multifactorial. Various factors including altered biomechanical stresses, surgical disruption of soft tissue and the natural history of cervical disc disease contribute to the development of ASP. General factors associated with disc degeneration including gender, age, smoking and sports may play a role in the development of ASP. Postoperative sagittal alignment and type of surgery are also considered potential causes of ASP. Therefore, a spine surgeon must be particularly careful to avoid unnecessary disruption of the musculoligamentous structures, reduced risk of direct injury to the disc during dissection and maintain a safe margin between the plate edge and adjacent vertebrae during anterior cervical fusion. PMID:27340541

  1. Treatment of Anterior Cruciate Ligament Injuries.

    PubMed

    Sanders, James O; Brown, Gregory A; Murray, Jayson; Pezold, Ryan; Sevarino, Kaitlyn S

    2016-08-01

    The American Academy of Orthopaedic Surgeons has developed the Appropriate Use Criteria (AUC) document Treatment of Anterior Cruciate Ligament Injuries. Evidence-based information, in conjunction with the clinical expertise of physicians, was used to develop the criteria to improve patient care and obtain the best outcomes while considering the subtleties and distinctions necessary in making clinical decisions. The AUC clinical patient scenarios were derived from patient indications that generally accompany an anterior cruciate ligament injury, as well as from current evidence-based clinical practice guidelines and supporting literature. The 56 patient scenarios and 8 treatments were developed by the Writing Panel, a group of clinicians who are specialists in this AUC topic. Lastly, a separate, multidisciplinary Voting Panel (made up of specialists and nonspecialists) rated the appropriateness of treatment of each patient scenario using a 9-point scale to designate a treatment as Appropriate (median rating, 7 to 9), May Be Appropriate (median rating, 4 to 6), or Rarely Appropriate (median rating, 1 to 3). PMID:27355285

  2. Adjacent Segment Pathology after Anterior Cervical Fusion.

    PubMed

    Chung, Jae Yoon; Park, Jong-Beom; Seo, Hyoung-Yeon; Kim, Sung Kyu

    2016-06-01

    Anterior cervical fusion has become a standard of care for numerous pathologic conditions of the cervical spine. However, subsequent development of clinically significant disc disease at levels adjacent to fused discs is a serious long-term complication of this procedure. As more patients live longer after surgery, it is foreseeable that adjacent segment pathology (ASP) will develop in increasing numbers of patients. Also, ASP has been studied more intensively with the recent popularity of motion preservation technologies like total disc arthroplasty. The true nature and scope of ASP remains poorly understood. The etiology of ASP is most likely multifactorial. Various factors including altered biomechanical stresses, surgical disruption of soft tissue and the natural history of cervical disc disease contribute to the development of ASP. General factors associated with disc degeneration including gender, age, smoking and sports may play a role in the development of ASP. Postoperative sagittal alignment and type of surgery are also considered potential causes of ASP. Therefore, a spine surgeon must be particularly careful to avoid unnecessary disruption of the musculoligamentous structures, reduced risk of direct injury to the disc during dissection and maintain a safe margin between the plate edge and adjacent vertebrae during anterior cervical fusion. PMID:27340541

  3. Anterior eye protection with orbital neoplasia

    SciTech Connect

    Hancock, S.L.

    1986-01-01

    The administration of adequate doses of radiation to tumors involving the orbit and surrounding facial structures and sinuses is often complicated by the need to protect the sensitive ocular components, the lens and cornea. A technique has been devised that uses four photon beam fields and an optional electron field to treat the contents of both orbits and adjacent sinuses with effective, reproducible protection of cornea and lens. Essential features include: alignment of the corneal surfaces with the central plane of rotation of the treatment machine, use of a narrow eye block across the entire beam to shield a strip equal to the width of the cornea, positioned symmetrically across the central plane of rotation, fine alignment of the eye block with both corneal surfaces by altering pedestal angle, treatment with paired, wedged, anterior oblique fields to encompass desired orbital and sinus volumes with additional blocking placed as needed, and complementary, lateral strip fields using collimators set to eye block thickness to equalize dose in the posterior orbit shielded by the strip eye block. A similar anterior electron beam strip field may be added to boost the medial orbit and ethmoid regions covered by the eye block. Bite block head immobilization and easy, direct daily visualization of block position assures eye protection for each treatment and provides substantial reduction in dose to the cornea, lens and iris. Additional blocking may be incorporated to provide partial lacrimal and parotid sparing.

  4. Meta-Analysis Comparing Zero-Profile Spacer and Anterior Plate in Anterior Cervical Fusion

    PubMed Central

    Lu, Teng; Liang, Baobao; Xu, Junkui; Zhou, Jun; Lv, Hongjun; Qin, Jie; Cai, Xuan; Huang, Sihua; Li, Haopeng; Wang, Dong; He, Xijing

    2015-01-01

    Background Anterior plate fusion is an effective procedure for the treatment of cervical spinal diseases but is accompanied by a high incidence of postoperative dysphagia. A zero profile (Zero-P) spacer is increasingly being used to reduce postoperative dysphagia and other potential complications associated with surgical intervention. Studies comparing the Zero-P spacer and anterior plate have reported conflicting results. Methodology A meta-analysis was conducted to compare the safety, efficacy, radiological outcomes and complications associated with the use of a Zero-P spacer versus an anterior plate in anterior cervical spine fusion for the treatment of cervical spinal disease. We comprehensively searched PubMed, Embase, the Cochrane Library and other databases and performed a meta-analysis of all randomized controlled trials (RCTs) and prospective or retrospective comparative studies assessing the two techniques. Results Ten studies enrolling 719 cervical spondylosis patients were included. The pooled data showed significant differences in the operation time [SMD = –0.58 (95% CI = −0.77 to 0.40, p < 0.01)] and blood loss [SMD = −0.40, 95% CI (−0.59 to –0.21), p < 0.01] between the two groups. Compared to the anterior plate group, the Zero-P group exhibited a significantly improved JOA score and reduced NDI and VAS. However, anterior plate fusion had greater postoperative segmental and cervical Cobb’s angles than the Zero-P group at the last follow-up. The fusion rate in the two groups was similar. More importantly, the Zero-P group had a lower incidence of earlier and later postoperative dysphagia. Conclusions Compared to anterior plate fusion, Zero-P is a safer and effective procedure, with a similar fusion rate and lower incidence of earlier and later postoperative dysphagia. However, the results of this meta-analysis should be accepted with caution due to the limitations of the study. Further evaluation and large-sample RCTs are required to

  5. An in vivo comparison of anterior tibial translation and strain in the anteromedial band of the anterior cruciate ligament.

    PubMed

    Fleming, B C; Beynnon, B D; Nichols, C E; Johnson, R J; Pope, M H

    1993-01-01

    The objective of this in vivo study was to determine if strain in the anteromedial band (AMB) of the anterior cruciate ligament (ACL) may be predicted by an external measurement of anterior tibial-femoral translation. A Hall effect strain transducer was implanted on the AMB of five human subjects with normal intact ACLs. AMB strain was then measured during anterior shear loading of the tibia relative to the femur, with the knee flexed to 30 and 90 degrees, simulating the loads applied in the Lachman and anterior drawer tests, respectively. The Knee Signature System, a commercially available arthrometer, was used to simultaneously measure anterior tibial translation relative to the femur. The resulting AMB strains and translations during anterior shear loading of the tibia with respect to the femur at 30 and 90 degrees were compared using a regression analysis to determine if AMB strain could be predicted from a measure of anterior tibiofemoral translation at either flexion angle. AMB strain at 150 N anterior shear load at 30 degrees flexion (3.0%) was significantly greater than that at 150 N anterior shear load at 90 degrees flexion (0.9%). During anterior shear loading at 30 degrees flexion, AMB strain correlated with anterior tibial translation (r2 = 0.59). However, there was no significant correlation between AMB strain and anterior tibial translation for anterior shear loading at 90 degrees flexion (r2 = 0.002). Therefore, AMB strain was not accurately predicted from an external measurement of tibial displacement at 90 degrees in this experiment. PMID:8423168

  6. Anterior segment imaging in glaucoma: An updated review

    PubMed Central

    Maslin, Jessica S; Barkana, Yaniv; Dorairaj, Syril K

    2015-01-01

    Anterior segment imaging allows for an objective method of visualizing the anterior segment angle. Two of the most commonly used devices for anterior segment imaging include the anterior segment optical coherence tomography (AS-OCT) and the ultrasound biomicroscopy (UBM). AS-OCT technology has several types, including time-domain, swept-source, and spectral-domain-based configurations. We performed a literature search on PubMed for articles containing the text “anterior segment OCT,” “ultrasound biomicroscopy,” and “anterior segment imaging” since 2004, with some pertinent references before 2004 included for completeness. This review compares the advantages and disadvantages of AS-OCT and UBM, and summarizes the most recent literature regarding the importance of these devices in glaucoma diagnosis and management. These devices not only aid in visualization of the angle, but also have important postsurgical applications in bleb and tube imaging. PMID:26576519

  7. Microanatomy of the perforators of the anterior communicating artery complex.

    PubMed

    Camuscu, H; Dujovny, M; Abd el-Bary, T; Beristain, X; Viñas, F C

    1997-12-01

    We describe the microanatomy of the perforating arteries arising from the anterior communicating artery complex (5 mm distal of the anterior cerebral artery, the anterior communicating artery, and 5 mm proximal of the distal anterior cerebral artery). Thirteen unfixed human brains were used in this study. The origin and number of perforators are described, as is the site of brain penetration, and results are correlated with previous studies. The hemodynamics of blood flow in relation to the formation of an anterior communicating artery aneurysm and different surgical approaches are mentioned. The neuropsychological outcome after aneurysm clipping with regards to the pattern of blood supply from the anterior cerebral artery complex is also discussed. PMID:9427956

  8. Successful anterior fusion following posterior cervical fusion for revision of anterior cervical discectomy and fusion pseudarthrosis.

    PubMed

    Elder, Benjamin D; Sankey, Eric W; Theodros, Debebe; Bydon, Mohamad; Rory Goodwin, C; Lo, Sheng-Fu; Kosztowski, Thomas A; Belzberg, Allen J; Wolinsky, Jean-Paul; Sciubba, Daniel M; Gokaslan, Ziya L; Bydon, Ali; Witham, Timothy F

    2016-02-01

    Pseudarthrosis occurs after approximately 2-20% of anterior cervical discectomy and fusion (ACDF) procedures; it is unclear if posterior or anterior revision should be pursued. In this study, we retrospectively evaluate the outcomes in 22 patients with pseudarthrosis following ACDF and revision via posterior cervical fusion (PCF). Baseline demographics, preoperative symptoms, operative data, time to fusion failure, symptoms of pseudarthrosis, and revision method were assessed. Fusion outcome and clinical outcome were determined at last follow-up (LFU). Thirteen females (59%) and 9 (41%) males experienced pseudarthrosis at a median of 11 (range: 3-151)months after ACDF. Median age at index surgery was 51 (range: 33-67)years. All patients with pseudarthrosis presented with progressive neck pain, with median visual analog scale (VAS) score of 8 (range: 0-10), and/or myeloradiculopathy. Patients with pseudarthrosis <12 months compared to >12 months after index surgery were older (p=0.013), had more frequent preoperative neurological deficits (p=0.064), and lower baseline VAS scores (p=0.006). Fusion was successful after PCF in all patients, with median time to fusion of 10 (range: 2-14)months. Eighteen patients fused both anteriorly and posteriorly, two patients fused anteriorly only, and two patients fused posteriorly only. Median VAS neck score at LFU significantly improved from the time of pseudarthrosis (p=0.012). While uncommon, pseudarthrosis may occur after ACDF. All patients achieved successful fusion after subsequent posterior cervical fusion, with 91% fusing a previous anterior pseudarthrosis after posterior stabilization. Neck pain significantly improved by LFU in the majority of patients in this study. PMID:26482460

  9. Review of 31 cases of anterior thoracolumbar fixation with the anterior thoracolumbar locking plate system.

    PubMed

    Wilson, J A; Bowen, S; Branch, C L; Meredith, J W

    1999-07-15

    Anterior fixation devices for the thoracolumbar spine have gained wide acceptance as viable alternatives to long-segment posterior fixation in cases of thoracolumbar spine trauma. This review was undertaken to evaluate the safety and efficacy of the Synthes anterior thoracolumbar locking plate (ATLP) system. Over a 3-year period, 31 patients with unstable traumatic fractures of the thoracolumbar spine underwent corpectomy, placement of a structural bone graft, and anterior fixation in which the Synthes ATLP system was used. Long-term follow-up data were obtained in 29 patients. Two patients were lost to follow up, one at 4 months and the other at 1 year. In the remaining patients, the average length of follow up was 20 months. In all patients radiographic evidence of solid bone fusion was demonstrated on follow-up plain x-ray films, and there were no signs or symptoms of pseudarthrosis. No patient suffered neurological deterioration as a result of surgery, and there was relatively little morbidity associated with this plating system. To date, none of the patients in this study has developed any delayed complications related to the fixation device. In one patient, who had sustained a severe flexion injury, loosening of the anterior fixation device occurred, and the patient developed progressive kyphosis, which required a posterior stabilization procedure. These results appear slightly better than those obtained in published studies in which other anterior plating systems were used, indicating that this system is safe and effective in the treatment of unstable fractures of the thoracolumbar spine. PMID:16918232

  10. Anterior mitral annulus caseoma: as benign as posterior counterparts?

    PubMed

    Mazzucco, Alessandro; Abbasciano, Riccardo; Onorati, Francesco; Brognoli, Gabriele; Fanti, Diego; Gottin, Leonardo; Faggian, Giuseppe

    2016-01-01

    Mitral annular caseoma is a common incidental finding involving the posterior annulus. It has an innocent nature, with the exception of its endocarditic degeneration and/or a stenotic functional effect when exophytic. We report an exceptionally rare isolated anterior mitral annular caseoma involving also the anterior mitral leaflet and affecting its physiologic systolic movement, thus resulting in a restricting anterior leaflet motion responsible for mitral insufficiency. The case was successfully treated by complex mitral valve repair. PMID:26522681

  11. Anterolateral Extra-articular Soft Tissue Reconstruction in Anterolateral Rotatory Instability of the Knee.

    PubMed

    Kernkamp, Willem A; van de Velde, Samuel K; Bakker, Eric W P; van Arkel, Ewoud R A

    2015-12-01

    Anterolateral rotatory instability (ALRI) occurs after injury to the anterior cruciate ligament (ACL) and the anterolateral structures of the knee. We present a technique for anterolateral extra-articular soft-tissue (ALES) reconstruction of the knee that can be used in revision ACL reconstruction cases, cases of persistent ALRI after adequate ACL reconstruction, and cases with severe ALRI after primary ACL rupture. The surgeon performs ALES reconstruction with a strip of iliotibial tract autograft while respecting the anatomic origin and insertion of the anterolateral ligament. The purpose of this reconstruction is to restore the normal anterolateral rotatory stability of the knee in ALES-deficient patients. PMID:27284525

  12. Save or sacrifice the internal mammary pedicle during anterior mediastinotomy?

    PubMed

    Apostolakis, Efstratios; Papakonstantinou, Nikolaos A; Chlapoutakis, Serafeim; Prokakis, Christos

    2014-07-01

    Ligation and dissection of internal mammary vessels is the most under-estimated complication of anterior mediastinotomy. However, patients requiring anterior mediastinotomy may experience long survival that makes the development of ischemic heart disease throughout their life possible. Therefore, the un-judicial sacrifice of the internal mammary pedicle may deprive them from the benefit to have their internal mammary artery used as a graft in order to successfully bypass severe left anterior descending artery stenoses. We recommend the preservation of the internal mammary pedicle during anterior mediastinotomy, which should be a common message among our colleagues from the beginning of their training. PMID:24987471

  13. Modes of storage ring coherent instabilities

    SciTech Connect

    Wang, J.M.

    1986-12-01

    Longitudinal impedance in a beam and various modes of longitudinal coherent instabilities are discussed. The coasting beam coherent instability, microwave instability, and single-bunch longitudinal coherent instabilities are considered. The Vlasov equation is formulated, and a method of solving it is developed. The synchrotron modes are treated, which take the possible bunch shape distortion fully into consideration. A method of treating the synchrotron mode coupling in the case of a small bunch is discussed which takes advantage of the fact that only a few of the synchrotron modes can contribute in such a case. The effect of many bunches on the coherent motion of the beam and the longitudinal symmetric coupled bunch modes are discussed. The transverse impedance is then introduced, and the transverse coasting beam instability is discussed. Various bunched beam instabilities are discussed, including both single bunch instabilities and coupled bunch instabilities. The Vlasov equation for transverse as well as longitudinal motion of particles is introduced as well as a method of solving it within a linear approximation. Head-tail modes and short bunch instabilities and strong coupling instabilities in the long bunch case are covered. (LEW)

  14. 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.

  15. Failure of the human lumbar motion-segments resulting from anterior shear fatigue loading.

    PubMed

    Skrzypiec, Daniel M; Nagel, Katrin; Sellenschloh, Kay; Klein, Anke; Püschel, Klaus; Morlock, Michael M; Huber, Gerd

    2016-08-01

    An in-vitro experiment was designed to investigate the mode of failure following shear fatigue loading of lumbar motion-segments. Human male lumbar motion-segments (age 32-42 years, n=6) were immersed in Ringer solution at 37°C and repeatedly loaded, using a modified materials testing machine. Fatigue loading consisted of a sinusoidal shear load from 0 N to 1,500 N (750 N±750 N) applied to the upper vertebra of the motion-segment, at a frequency of 5 Hz. During fatigue experiments, several failure events were observed in the dynamic creep curves. Post-test x-ray, CT and dissection revealed that all specimens had delamination of the intervertebral disc. Anterior shear fatigue predominantly resulted in fracture of the apophyseal processes of the upper vertebrae (n=4). Exposure to the anterior shear fatigue loading caused motion-segment instability and resulted in vertebral slip corresponding to grade I and 'mild' grade II spondylolisthesis, as observed clinically. PMID:26829975

  16. Prognosis of anterior cruciate ligament reconstruction: a data-driven approach

    PubMed Central

    Chandra, Abhijit; Kar, Oliva; Wu, Kuan-Chuen; Hall, Michelle; Gillette, Jason

    2015-01-01

    Individuals who suffer anterior cruciate ligament (ACL) injury are at higher risk of developing knee osteoarthritis (OA) and almost 50% display symptoms 10–20 years post injury. Anterior cruciate ligament reconstruction (ACLR) often does not protect against knee OA development. Accordingly, a multi-scale formulation for data-driven prognosis (DDP) of post-ACLR is developed. Unlike traditional predictive strategies that require controlled off-line measurements or ‘training’ for determination of constitutive parameters to derive the transitional statistics, the proposed DDP algorithm relies solely on in situ measurements. The proposed DDP scheme is capable of predicting onset of instabilities. As the need for off-line testing (or training) is obviated, it can be easily implemented for ACLR, where such controlled a priori testing is almost impossible to conduct. The DDP algorithm facilitates hierarchical handling of the large dataset and can assess the state of recovery in post-ACLR conditions based on data collected from stair ascent and descent exercises of subjects. The DDP algorithm identifies inefficient knee varus motion and knee rotation as primary difficulties experienced by some of the post-ACLR population. In such cases, levels of energy dissipation rate at the knee, and its fluctuation may be used as measures for assessing progress after ACL reconstruction.

  17. Failure of the human lumbar motion-segments resulting from anterior shear fatigue loading

    PubMed Central

    SKRZYPIEC, Daniel M.; NAGEL, Katrin; SELLENSCHLOH, Kay; KLEIN, Anke; PÜSCHEL, Klaus; MORLOCK, Michael M.; HUBER, Gerd

    2016-01-01

    An in-vitro experiment was designed to investigate the mode of failure following shear fatigue loading of lumbar motion-segments. Human male lumbar motion-segments (age 32–42 years, n=6) were immersed in Ringer solution at 37°C and repeatedly loaded, using a modified materials testing machine. Fatigue loading consisted of a sinusoidal shear load from 0 N to 1,500 N (750 N±750 N) applied to the upper vertebra of the motion-segment, at a frequency of 5 Hz. During fatigue experiments, several failure events were observed in the dynamic creep curves. Post-test x-ray, CT and dissection revealed that all specimens had delamination of the intervertebral disc. Anterior shear fatigue predominantly resulted in fracture of the apophyseal processes of the upper vertebrae (n=4). Exposure to the anterior shear fatigue loading caused motion-segment instability and resulted in vertebral slip corresponding to grade I and ‘mild’ grade II spondylolisthesis, as observed clinically. PMID:26829975

  18. ANTERIOR CRUCIATE LIGAMENT INJURY: TREATMENT AND REHABILITATION. CURRENT PERSPECTIVES AND TRENDS

    PubMed Central

    Arliani, Gustavo Gonçalves; Astur, Diego da Costa; Kanas, Michel; Kaleka, Camila Cohen; Cohen, Moises

    2015-01-01

    Objective: The aim of this study was to evaluate the procedures used by knee surgeons in Brazil for treating and rehabilitating anterior cruciate ligament injuries. Methods: A questionnaire consisting of 21 closed questions was developed, addressing topics relating to treatment and rehabilitation after anterior cruciate ligament reconstruction. The questionnaire was applied to Brazilian knee surgeons during the three days of the 42nd Brazilian Congress of Orthopedics and Traumatology in 2010. Results: A total of 226 surgeons filled out the questionnaire completely. The most commonly used types of graft were hamstrings tendons and the central third of the ipsilateral patellar tendon, which were used by 82.3% and 53.5% of the sample, respectively. The technique of reconstruction with a single transtibial band was the first preference and was used by 66.4% of the participants. A period of 1 to 4 weeks between injury and surgical procedure was considered ideal by most participants (52.65%). Complaints from patients that the knee was ‘giving way’ or unstable and presence of a positive pivot shift maneuver were the most decisive factors considered in making the decision to operate the patient. Patient satisfaction and absence of complaints of instability during the postoperative period were the criteria deemed to be most important for the surgery to be considered a success. Conclusions: There are clearly evolving trends in treating and rehabilitating the anterior cruciate ligament in Brazil. However, more prospective controlled studies are needed in order to evaluate the clinical and scientific benefits of these trends. PMID:27042620

  19. Instability of the elbow treated with semiconstrained total elbow arthroplasty.

    PubMed

    Ramsey, M L; Adams, R A; Morrey, B F

    1999-01-01

    The results of nineteen semiconstrained modified Coonrad-Morrey total elbow arthroplasties performed in nineteen patients to treat instability were evaluated at an average of seventy-two months (range, twenty-five to 128 months) postoperatively. Preoperatively, all patients had either a flail elbow or gross instability of the elbow that prevented useful function of the extremity. The instability of sixteen elbows was the result of a traumatic injury or of the treatment of such an injury. The most recent result was satisfactory for sixteen elbows and unsatisfactory for three. The average overall Mayo elbow performance score increased from 44 points preoperatively to 86 points postoperatively. At the most recent follow-up examination, no elbow was unstable. The average arc of flexion was from 25 degrees (range, 0 to 60 degrees) to 128 degrees (range, 30 to 142 degrees), which represented a 58-degree increase from the preoperative average arc. Sixteen patients had little or no pain after the arthroplasty. There were four complications in four patients. Three complications (loosening of the humeral component in one patient and a fracture of the ulnar component in two) occurred postoperatively; all three were treated with a revision procedure. The other complication (a fracture of the olecranon) occurred intraoperatively and was treated with tension-band fixation; the most recent outcome was not affected. Radiographically, one patient had complete (type-V) radiolucency about the humeral component. None of the nine patients for whom true anteroposterior radiographs were available had evidence of wear of the bushings. The bone graft behind the anterior flange of the humeral prosthesis was mature in fourteen elbows, incomplete in two, and resorbed in two. One patient was excluded from this analysis because radiographs were not available. Instability of the elbow resulting in the inability to use the extremity is a challenging clinical situation. However, in patients who

  20. Combined operative technique with anterior surgical approach and video-assisted thoracoscopic surgical lobectomy for anterior superior sulcus tumours.

    PubMed

    Yokoyama, Yuhei; Chen, Fengshi; Aoyama, Akihiro; Sato, Toshihiko; Date, Hiroshi

    2014-11-01

    Video-assisted thoracoscopic surgery (VATS) has been widely used, but surgical resections of superior sulcus tumours remain challenging because of their anatomical location. For such cases, less-invasive procedures, such as the anterior transcervical-thoracic and transmanubrial approaches, have been widely performed because of their excellent visualization of the subclavian vessels. Recently, a combined operative technique with an anterior surgical approach and VATS for anterior superior sulcus tumours has been introduced. Herein, we report three cases of anterior superior sulcus tumours successfully resected by surgical approaches combined with a VATS-based lobectomy. In all cases, operability was confirmed by VATS, and upper lobectomies with hilar and mediastinal lymph node dissections were performed. Subsequently, dissections of the anterior inlet of the tumours were performed using the transmanubrial approach in two patients and the anterior trans-cervical-thoracic approach in one patient. Both approaches provided excellent access to the anterior inlet of the tumour and exposure of the subclavian vessels, resulting in radical resection of the tumour with concomitant resection of the surrounding anatomical structures, including the chest wall and vessels. In conclusion, VATS lobectomy combined with the anterior surgical approach might be an excellent procedure for the resection of anterior superior sulcus tumours. PMID:25028075

  1. Infections in Anterior Cruciate Ligament Reconstruction

    PubMed Central

    Stucken, Charlton; Garras, David N.; Shaner, Julie L.; Cohen, Steven B.

    2013-01-01

    Context: Anterior cruciate ligament (ACL) reconstruction is a safe, common, and effective method of restoring stability to the knee after injury, but evolving techniques of reconstruction carry inherent risk. Infection after ACL reconstruction, while rare, carries a high morbidity, potentially resulting in a poor clinical outcome. Evidence Acquisition: Data were obtained from previously published peer-reviewed literature through a search of the entire PubMed database (up to December 2012) as well as from textbook chapters. Results: Treatment with culture-specific antibiotics and debridement with graft retention is recommended as initial treatment, but with persistent infection, consideration should be given to graft removal. Graft type likely has no effect on infection rates. Conclusion: The early diagnosis of infection and appropriate treatment are necessary to avoid the complications of articular cartilage damage and arthrofibrosis. PMID:24427432

  2. Alternaria keratitis after deep anterior lamellar keratoplasty.

    PubMed

    Naik, Mekhla; Mohd Shahbaaz; Sheth, Jay; Sunderamoorthy, S K

    2014-01-01

    To describe a case of Alternaria keratitis in a 30-year-old male patient who presented with bilateral vascularised central corneal opacity and underwent deep anterior lamellar keratoplasty (DALK) in the left eye. Patient was treated for recurrent epithelial defect with a bandage contact lens in the follow-up visits after DALK. Subsequently, patient presented with pigmented fungal keratitis, which on culture examination of the corneal scrapping demonstrated Alternaria species. Patient had to undergo a repeat DALK as the keratitis did not resolve with medical therapy alone. Patient did not have a recurrence for 11 months following the regraft. This case report highlights the importance of considering the Alternaria species as a possibile cause of non-resolving fungal keratitis after DALK. PMID:24669155

  3. [Treatment of anterior hypospadias. Place of balanoplasty].

    PubMed

    Juskiewenski, S; Vaysse, P; Guitard, J; Moscovici, J

    1983-01-01

    Authors report their experience of the treatment of anterior hypospadias which represent more than 71% of these cases operated all along the eight past years. The different aspects of these malformation are emphasized. For the majority of these cases the correction of the malformation may be obtained by a simple balanoplasty which gives the gland a normal form and height though directing the meatus forward; the redundant foreskin is excised and the penile skin torsion is corrected aligning the median raphe; a deficit of the ventral skin case be filled in with preputial flaps. This technic was used in fifty of the reported cases with very good results both functionally and cosmetically. This procedure is comparable to the technic described by J.W. Duckett and called Magpi for meatal advancement and glanduloplasty incorporated. The results reported here corroborate the good results already published. PMID:6850956

  4. Foreign body embedded in anterior chamber angle.

    PubMed

    Graffi, Shmuel; Tiosano, Beatrice; Ben Cnaan, Ran; Bahir, Jonathan; Naftali, Modi

    2012-01-01

    Introduction. We present a case of a metallic foreign body embedded in the anterior chamber angle. After standing in close proximity to a construction worker breaking a tile, a 26-year-old woman using soft contact lens for the correction of mild myopia presented to emergency department for evaluation of a foreign body sensation of her right eye. Methods and Results. Diagnosis was confirmed by gonioscopic examination and a noncontrast CT scan of head and orbits. The foreign body was removed by an external approach without utilizing a magnet. The patient's final outcome was favorable. Discussion. The above is a rare clinical situation, which is impossible to detect on slit-lamp examination without a gonioscopic view. Proper imaging and a specific management are mandatory in order to achieve favorable outcome. PMID:23091762

  5. Multiple signals in anterior cingulate cortex

    PubMed Central

    Kolling, N; Behrens, TEJ; Wittmann, MK; Rushworth, MFS

    2016-01-01

    Activity in anterior cingulate cortex (ACC) has been linked both to commitment to a course of action, even when it is associated with costs, and to exploring or searching for alternative courses of action. Here we review evidence that this is due to the presence of multiple signals in ACC reflecting the updating of beliefs and internal models of the environment and encoding aspects of choice value, including the average value of choices afforded by the environment (‘search value’). We contrast this evidence with the influential view that ACC activity is better described as reflecting task difficulty. A consideration of cortical neural network properties explains why ACC may carry such signals and also exhibit sensitivity to task difficulty. PMID:26774693

  6. Patellotibial contusions in anterior cruciate ligament tears.

    PubMed

    Wissman, Robert D; England, Eric; Mehta, Kaushal; Nepute, Joshua; Von Fischer, Nathaniel; Apgar, Josh; Javadi, Ariyan

    2014-02-01

    Bone contusions are an important ancillary finding of many knee injuries. Not only are they a source of pain, they may suggest a mechanism of injury or a specific derangement of the knee joint. We have encountered a small number of patients being evaluated for anterior cruciate ligament (ACL) tears with unexplained patellar and tibial edema at magnetic resonance (MR) imaging. We present three individuals with contusions of the inferior patella with a corresponding contusion of the anteromedial tibial plateau. Internal derangements in these patients were similar to other individuals with acute ACL tears, however osseous contusions were more widespread. In conclusion, patellotibial contusions are rare and may indicate an injury with forces greater than usually encountered in most ACL tears. A careful search for uncommon associated injuries is prudent in these high-energy knee injuries. PMID:24037484

  7. Tibial Tubercle Osteotomy for Anterior Knee Pain

    PubMed Central

    Bonasia, Davide; Rosso, Federica; Cottino, Umberto; Governale, Giorgio; Cherubini, Valeria; Dettoni, Federico; Bruzzone, Matteo; Rossi, Roberto

    2016-01-01

    Objectives: The aim of this study was to evaluate the mid-term radiological and clinical outcomes of tibial tubercle osteotomy in patients affected by anterior knee pain. In addition, prognostic factors correlated with the outcomes were evaluated. Methods: The patients treated with tibial tubercle osteotomy (anteromedialization) for anterior knee pain between 2002 and 2014 were included. Exclusion criteria: 1) previous knee surgeries; 2) different procedures to treat anterior knee pain; 3) history of patellar dislocation, 4) Rheumatic conditions. Different variables were collected, as shown in. The patients were prospectively evaluated using the WOMAC short form and Kujala scores. An objective evaluation was performed looking for different potential risk factors and using part of the International Knee Documentation Committee (IKDC) score. Radiological evaluation was performed, including the congruence angle, the grade of osteoarthritis (Kellegren-Lawrence) and the patellar tilt angle. Three main outcomes were identified. The multiple logistic regression was used to analyze the correlation between the variables and a worse outcome. Results: 72 cases were included in the study (9 bilateral). 72.2% of the cases were female, and the average age was 42,2 years (SD15,9). The average BMI was 24.4 kg/m2 (SD5,2). In 70.8% of patients a lateral release was associated to the tibial tubercle osteotomy. 77.8% of patients were evaluated clinically, the remaining, who were unable to come for the visits, were interviewed and the subjective scores were administered by phone. The average follow-up was 68.4 months (SD35.5).In 62.5% of cases a valgus lower limb alignment was detected, with 25% and 39.3% of patients having respectively an increased femoral antiversion and foot pronation. Post-operatively there was a statistical significant improvement in all the scores. No differences in the pre-operative and post-operative congruence angle or patellar tilt were detected (p>0.05). All

  8. Development of the human anterior urethra.

    PubMed

    Altemus, A R; Hutchins, G M

    1991-10-01

    To further our understanding of the development of the anterior urethra a series of 38 normal human fetuses ranging from the end of the embryonic period proper to the third trimester of gestation were studied. Tissues prepared as serial histological sections were examined and appropriate specimens were reconstructed. The formation of the bulbar and spongy urethra occurred by proliferation of mesenchyme underlying the epithelium of the urethral folds, causing the creation of a tubular urethra by epithelial fusion in the ventral midline. The tubular urethra becomes invested by mesenchyme, the future corpus spongiosum. This process of fusion of the urethral folds extends to the glans penis. At this period of development the glans contains the urethral plate, a lamina of epithelium lacking a lumen. The mechanism of the subsequent connection of the spongy urethra to the canalized urethral plate has been the point of controversy. Our observations support the idea that 3 processes must act in synchrony to produce successful completion of the anterior urethra: 1) the prepuce forms by overgrowing the glans due to proliferation of the penile skin and subcutaneous tissues, and in so doing it continues the progression of closure of the urethral folds into the glans and forms the frenulum by its fusion on the ventral aspect, 2) the mesenchyme surrounding the prolongation of the urethra fuses with the mesenchyme of the glans, which before this time had existed as a mesenchymal structure distinct from the corpus spongiosum or corpus cavernosum and 3) the epithelium of the urethral plate within the glans, which underlies the epithelial tag, becomes canalized and develops continuity with the lumen of the spongy urethra. PMID:1895427

  9. Anterior Cingulate epilepsy: mechanisms and modulation

    PubMed Central

    Chang, Wei-Pang; Shyu, Bai-Chuang

    2014-01-01

    Epilepsy is a common neurological disorder, about 1% population worldwide suffered from this disease. In 1989, the International League Against Epilepsy (ILAE) classified anterior cingulate epilepsy as a form of frontal lobe epilepsy (FLE). FLE is the second most common type of epilepsy. Previous clinical studies showed that FLE account an important cause in refractory epilepsy, therefore to find alternative approach to modulate FLE is very important. Basic research using animal models and brain slice have revealed some insights on the epileptogenesis and modulation of seizure in anterior cingulate cortex (ACC). Interneurons play an important role in the synchronization of cingulate epilepsy. Research has shown that the epileptogenesis of seizure originated from mesial frontal lobe might be caused by a selective increase in nicotine-evoked γ-aminobutyric acid (GABA) inhibition, because the application of the GABAA receptor antagonist picrotoxin inhibited epileptic discharges. Gap junctions are also involved in the regulation of cingulate epilepsy. Previous studies have shown that the application of gap junction blockers could attenuate ACC seizures, while gap junction opener could enhance them in an in vitro preparation. μ-Opioid receptors have been shown to be involved in the epileptic synchronization mechanism in ACC seizures in a brain slice preparation. Application of the μ-opioid agonist DAMGO significantly abolished the ictal discharges in a 4-aminopyridine induced electrographic seizure model in ACC. Basic research has also found that thalamic modulation has an inhibitory effect on ACC seizures. Studies have shown that the medial thalamus may be a target for deep brain stimulation to cure ACC seizures. PMID:24427123

  10. Responsiveness of outcome measures in patients with superior labral anterior and posterior lesions

    PubMed Central

    Mowinckel, Petter; Schrøder, Cecilie Piene; Liavaag, Sigurd; Reikerås, Olav; Brox, Jens Ivar

    2014-01-01

    Background Evaluation of patients with superior labral anterior and posterior (SLAP) lesions requires outcome measures validated for the purpose. The present study aimed to evaluate the responsiveness of the Rowe score, Oxford Instability Shoulder Score (OISS), Western Ontario Shoulder Instability Index (WOSI) and EuroQol (EQ-5D and EQ-VAS) in patients treated for SLAP lesions. Methods Eighty-nine patients were included: 34 had arthroscopic labral repair, 28 had mini-open biceps tenodesis and 27 had physical treatment. The outcome measures were administrated before treatment and after 6 months. Responsiveness was evaluated using standardized response mean (SRM), area under receiver-operating characteristic curve (ROCAUC), reliable chance proportion (RCP) statistics and hypothesis testing. Minimal clinically important change (MCIC) estimates were reported. Results All outcome measures had high values of SRM (0.86–1.92). RCPs for the improved group were 68% to 79% for OISS, WOSI and Rowe score, and 15% to 49% for EuroQol. ROCAUC was >0.70 for all outcomes. MCIC estimates were 8 and 10 for OISS; 451 and 569 for WOSI; 17 and 18 for Rowe score; 0.39 and 0.53 for EQ-5D; and 35 and 41 for EQ-VAS. Responsiveness tested with hypotheses favours the shoulder-specific outcomes. Conclusions OISS, WOSI and Rowe score are more responsive than EuroQol in evaluation of patients with SLAP lesions.

  11. Fingering Instabilities in Dewetting Nanofluids

    NASA Astrophysics Data System (ADS)

    Pauliac-Vaujour, E.; Stannard, A.; Martin, C. P.; Blunt, M. O.; Notingher, I.; Moriarty, P. J.; Vancea, I.; Thiele, U.

    2008-05-01

    The growth of fingering patterns in dewetting nanofluids (colloidal solutions of thiol-passivated gold nanoparticles) has been followed in real time using contrast-enhanced video microscopy. The fingering instability on which we focus here arises from evaporatively driven nucleation and growth in a nanoscopically thin precursor solvent film behind the macroscopic contact line. We find that well-developed isotropic fingering structures only form for a narrow range of experimental parameters. Numerical simulations, based on a modification of the Monte Carlo approach introduced by Rabani et al. [Nature (London)NATUAS0028-0836 426, 271 (2003)10.1038/nature02087], reproduce the patterns we observe experimentally.

  12. Fingering instabilities in dewetting nanofluids.

    PubMed

    Pauliac-Vaujour, E; Stannard, A; Martin, C P; Blunt, M O; Notingher, I; Moriarty, P J; Vancea, I; Thiele, U

    2008-05-01

    The growth of fingering patterns in dewetting nanofluids (colloidal solutions of thiol-passivated gold nanoparticles) has been followed in real time using contrast-enhanced video microscopy. The fingering instability on which we focus here arises from evaporatively driven nucleation and growth in a nanoscopically thin precursor solvent film behind the macroscopic contact line. We find that well-developed isotropic fingering structures only form for a narrow range of experimental parameters. Numerical simulations, based on a modification of the Monte Carlo approach introduced by Rabani et al. [Nature (London) 426, 271 (2003)10.1038/nature02087], reproduce the patterns we observe experimentally. PMID:18518311

  13. Sheet Beam Klystron Instability Analysis

    SciTech Connect

    Bane, K.L.F.; Jensen, A.; Li, Z.; Stupakov, G.; Adolphsen, C.; /SLAC

    2009-05-08

    Using the principle of energy balance we develop a 2D theory for calculating growth rates of instability in a two-cavity model of a sheet beam klystron. An important ingredient is a TE-like mode in the gap that also gives a longitudinal kick to the beam. When compared with a self-consistent particle-in-cell calculation, with sheet beam klystron-type parameters, agreement is quite good up to half the design current, 65 A; at full current, however, other, current-dependent effects come in and the results deviate significantly.

  14. 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. PMID:24267214

  15. 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.

  16. Passive mitigation of mode instabilities

    NASA Astrophysics Data System (ADS)

    Jauregui, C.; Otto, H.-J.; Stutzki, F.; Jansen, F.; Limpert, J.; Tünnermann, A.

    2014-03-01

    The phenomenon of mode instabilities has quickly become the most limiting effect for a further scaling of the average power of fiber laser systems. Consequently it is of great importance to find solutions for this problem. In this work we propose two concrete possible passive mitigation strategies: the first one is based on the reduction of the heat load in the fiber, whereas the second one is based on the reduction of the pump absorption. In both cases a significant increase of the threshold is expected.

  17. 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.

  18. Surface instability in windblown sand.

    PubMed

    Kurtze, D A; Both, J A; Hong, D C

    2000-06-01

    We investigate the formation of ripples on the surface of windblown sand based on the one-dimensional model of Nishimori and Ouchi [Phys. Rev. Lett. 71, 197 (1993)], which contains the processes of saltation and grain relaxation. We carry out a nonlinear analysis to determine the propagation speed of the restabilized ripple patterns, and the amplitudes and phases of their first, second, and third harmonics. The agreement between the theory and our numerical simulations is excellent near the onset of the instability. We also determine the Eckhaus boundary, outside which the steady ripple patterns are unstable. PMID:11088369

  19. Bathtub vortex induced by instability.

    PubMed

    Mizushima, Jiro; Abe, Kazuki; Yokoyama, Naoto

    2014-10-01

    The driving mechanism and the swirl direction of the bathtub vortex are investigated by the linear stability analysis of the no-vortex flow as well as numerical simulations. We find that only systems having plane symmetries with respect to vertical planes deserve research for the swirl direction. The bathtub vortex appearing in a vessel with a rectangular cross section having a drain hole at the center of the bottom is proved to be induced by instability when the flow rate exceeds a threshold. The Coriolis force is capable of determining the swirl direction to be cyclonic. PMID:25375427

  20. Arthroscopic Repair of Ankle Instability.

    PubMed

    Sorensen, Matthew D; Baca, John; Arbuckle, Keith

    2016-10-01

    Arthroscopic lateral ankle stabilization procedures have been described for many years. New technological advances and a deeper understanding of the pathobiomechanics involved in chronic lateral ankle instability have allowed an expansion of arthroscopic approaches to this common pathology. As experience is gained and outcomes within the patient profile are understood, the authors feel that the arthroscopic approach to lateral ankle stabilization may prove superior to traditional methods secondary to the risk and traditional complications that are mitigated within minimally invasive arthroscopic approaches. Additionally, the arthroscopic approach may allow a quicker return to ballistic sport and decrease time for rehabilitation. PMID:27599440

  1. 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.

  2. Absolute Instability in Coupled-Cavity TWTs

    NASA Astrophysics Data System (ADS)

    Hung, D. M. H.; Rittersdorf, I. M.; Zhang, Peng; Lau, Y. Y.; Simon, D. H.; Gilgenbach, R. M.; Chernin, D.; Antonsen, T. M., Jr.

    2014-10-01

    This paper will present results of our analysis of absolute instability in a coupled-cavity traveling wave tube (TWT). The structure mode at the lower and upper band edges are respectively approximated by a hyperbola in the (omega, k) plane. When the Briggs-Bers criterion is applied, a threshold current for onset of absolute instability is observed at the upper band edge, but not the lower band edge. The nonexistence of absolute instability at the lower band edge is mathematically similar to the nonexistence of absolute instability that we recently demonstrated for a dielectric TWT. The existence of absolute instability at the upper band edge is mathematically similar to the existence of absolute instability in a gyroton traveling wave amplifier. These interesting observations will be discussed, and the practical implications will be explored. This work was supported by AFOSR, ONR, and L-3 Communications Electron Devices.

  3. 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

  4. 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.

  5. Mode-locking via dissipative Faraday instability.

    PubMed

    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

  6. 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.

  7. 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.

  8. [Long-term follow up of anterior cruciate ligament reconstruction using autologous tendon graft augmented with alloplasty (Kennedy LAD)].

    PubMed

    Riel, K A; Bernett, P

    1990-11-01

    From October 1983 to January 1990 in 493 patients 499 injured anterior cruciate ligaments were reconstructed by a composite tendon graft. The autogenous graft, semitendinosus tendon or quadriceps-patella periost-patellar tendon, both anatomically attached distally, was augmented with the polypropylene braid (Kennedy LAD). In the period of January to November 1984 in 81 patients anterior cruciate ligament replacement was performed. A retrospective 2-years follow-up in 72 patients and a second 5-years follow-up in 67 of those 72 patients was possible. There were 38 patients with an acute rupture and 34 patients with chronic instability. Clinical and instrumented laxity revealed a mean displacement difference of not more than 3 mm in 84% of the patients in comparison of the involved with the normal knee at the 2-years and 5-years follow-up. 80% of strength analyses showed a physiological balance of quadriceps and hamstrings in the 5-years follow-up. In the 2-years follow-up only 41% of patients practiced former sports activities again, whereas in the 5-years follow-up 80% of the patients were able to join former sports. 80 to 100 points of Lysholm score demonstrating good to very good results were reached in 91% of the patients. Especially cartilage damages in cases of chronic instabilities worsened the results mentioned by the patients. PMID:2282840

  9. A new parameter for predicting crossflow instability

    NASA Technical Reports Server (NTRS)

    Kohama, Y.; Davis, S.

    1991-01-01

    Instability of boundary-layer over a concave wall and a rotating disk which were thought to be essentially different in instability sources, are compared in order to investigate whether or not a single crossflow parameter can be defined. Using a newly defined crossflow parameter, prediction was attempted on a yawed cylinder boundary-layer transition. By comparing the calculation with experiment, it was found out that this parameter can document fairly well the onset condition of the crossflow instability.

  10. Observation of Parametric Instability in Advanced LIGO.

    PubMed

    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

    2015-04-24

    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. PMID:25955042

  11. Modulational instabilities in relativistic pair plasmas

    NASA Astrophysics Data System (ADS)

    Mendonça, J. T.

    2016-05-01

    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.

  12. Observations of the PSR transverse instability

    SciTech Connect

    Colton, E. ); Fitzgerald, D.; Hardek, T.; Macek, R.J.; Plum, M.A.; Thiessen, H.A.; Wang, T.S. ); Neuffer, D. )

    1991-01-01

    A fast instability with beam loss is observed in the Los Alamos Proton Storage Ring (PSR) when the injected beam current exceeds thresholds, with both bunched and unbunched beams. Large coherent transverse oscillations occur before and during beam loss. Recent observations of the instability indicate that it is an e-p''-type instability, driven by coupled oscillations due to electrons trapped within the proton beam. 5 refs., 3 figs.

  13. Subsequent Surgery after Revision Anterior Cruciate Ligament Reconstruction

    PubMed Central

    Ding, David; Group, Mars

    2016-01-01

    Objectives: Failure or reinjury after anterior cruciate ligament (ACL) reconstruction can lead to recurrent instability and concomitant intra-articular injuries. While revision ACL reconstruction (rACLR) can be performed to restore knee stability and improve patient activity level, outcomes after these surgeries are reported to be inferior to primary ACL reconstruction. Further reoperation after rACLR can have an even more profound effect on patient satisfaction and outcome. Yet, there is a current lack of information regarding the rate and risk factors for subsequent surgery after rACLR. Methods: 1205 patients who underwent rACLR were enrolled between 2006 and 2011, comprising the prospective cohort. Two-year questionnaire follow-up was obtained on 989 (82%), while telephone follow-up was obtained on 1112 (92%). If a patient reported having a subsequent surgery, operative reports detailing the subsequent procedure(s) were obtained and categoriezed. A repeated meaures ANOVA was used to reveal significatnt differences in patient reported outcomes. Multivariate regression analysis was performed to determine independent risk factors for reoperation. Results: One hundred and twenty-two patients (10.1%) underwent a total of 172 subsequent procedures on the ipsilateral knee at 2-year follow-up. Of the reoperation procedures, 26.7% were meniscus procedures (69% meniscectomy, 26% repair), 18.6% were subsequent rACLR, 17.4% were cartilage procedures (61% chondroplasty, 17% microfracture, and 13% mosaicplasty), 10% hardware removal, and 9.3% were procedures for arthrofibrosis such has lysis of adhesions and synovectomy. Patients who had reoperations had significantly lower IKDC, KOOS symptoms and pain scores, and WOMAC stiffness scores at two-year follow up. Multivariate analysis revealed that patients under 20 years old were 2.1 times more likely than patients aged 20-29 to have a reoperation. Use of allograft at the time of rACLR and staged revision (bone grafting of

  14. Superior Labrum Anterior Posterior Lesions and Associated Injuries

    PubMed Central

    Beyzadeoglu, Tahsin; Circi, Esra

    2015-01-01

    Background: Superior labrum anterior posterior (SLAP) lesions often cause shoulder pain, dysfunction, and instability. Professional athletes require a high level of shoulder function for competition and overhead activities. Purpose: To evaluate elite athletes who had arthroscopic surgery for common shoulder pathologies and SLAP lesions with a follow-up of more than 3 years. The associated intra-articular pathologies and return to play were documented. Study Design: Case series; Level of evidence, 4. Methods: Thirty-five shoulders in 34 elite athletes (4 women and 30 men; mean age, 25 years [range, 18-32 years]) had arthroscopic repair of SLAP lesions and accompanying Bankart or rotator cuff tears between January 2008 and November 2011. The documentation included patient symptoms, physical examination, radiological analysis with radiographs, and magnetic resonance imaging. Shoulder function was evaluated preoperatively and at follow-up using American Shoulder and Elbow Surgeons (ASES) and Kerlan Jobe Orthopaedic Clinic (KJOC) scores. The mean follow-up was 52 months. Results: Isolated SLAP lesions were seen in 17.1% of patients, SLAP lesions and partial cuff tear occurred in 25.7%, associated Bankart lesions in 37.1%, full-thickness rotator cuff tears in 8.6%, Bankart and posterior labrum lesions in 8.6%, and Bankart and full-thickness rotator cuff tears in 2.9%. Return to play was a mean 6.4 ± 1.5 months. The mean postoperative ASES and KJOC scores were 89.6 ± 4.6 and 80.9 ± 6.8, respectively, compared with preoperative scores of 64.0 ± 7.2 and 50.5 ± 10.3 (t test, P < .01). Conclusion: The majority (88.2%) of professional athletes returned to their preinjury levels. SLAP lesions may frequently occur with Bankart lesions and rotator cuff tears. A high rate of return to sport at the same level of athletic performance can be achieved by anatomic repair and effective rehabilitation. PMID:26665050

  15. Return to Play Following Anterior Cruciate Ligament Reconstruction.

    PubMed

    Morris, Ryan C; Hulstyn, Michael J; Fleming, Braden C; Owens, Brett D; Fadale, Paul D

    2016-10-01

    Anterior cruciate ligament reconstructions are commonly performed in an attempt to return an athlete to sports activities. Accelerated rehabilitation has made recovery for surgery more predictable and shortened the timeline for return to play. Despite success with and advancements in anterior cruciate ligament reconstructions, some athletes still fail to return to play. PMID:27543405

  16. Anterior chamber cholesterolosis in a patient with retinoblastoma.

    PubMed

    Hong, Bryan K; Say, Emil Anthony T; Chévez-Barrios, Patricia; Lee, Thomas C; Kim, Jonathan W

    2016-01-01

    Anterior chamber cholesterolosis is a rare phenomenon typically associated with non-neoplastic conditions such as hyphema or Coats disease; it has never been reported to be associated with intraocular malignancy. We report a case of anterior chamber cholesterolosis presenting in the setting of retinoblastoma and discuss clinical features relevant for its differentiation from Coats disease. PMID:27330481

  17. Reduced Anterior Cingulate Cortex Glutamatergic Concentrations in Childhood Major Depression

    ERIC Educational Resources Information Center

    Mirza, Yousha; Tang, Jennifer; Russell, Aileen; Banerjee, S. Preeya; Bhandari, Rashmi; Ivey, Jennifer; Rose, Michelle; Moore, Gregory J.; Rosenberg, David R.

    2004-01-01

    Objective: To examine in vivo glutamatergic neurochemical alterations in the anterior cingulate cortex of children with major depressive disorder (MDD). Method: Single-voxel proton magnetic resonance spectroscopic ([.sup.1]H-MRS) examinations of the anterior cingulate cortex were conducted in 13 psychotropic-naive children and adolescents with MDD…

  18. Anterior chamber cholesterolosis in a patient with retinoblastoma

    PubMed Central

    Hong, Bryan K.; Say, Emil Anthony T.; Chévez-Barrios, Patricia; Lee, Thomas C.; Kim, Jonathan W.

    2016-01-01

    Summary Anterior chamber cholesterolosis is a rare phenomenon typically associated with non-neoplastic conditions such as hyphema or Coats disease; it has never been reported to be associated with intraocular malignancy. We report a case of anterior chamber cholesterolosis presenting in the setting of retinoblastoma and discuss clinical features relevant for its differentiation from Coats disease. PMID:27330481

  19. Experimental study of low frequency drift instability

    SciTech Connect

    Ioffe, M.S.; Kanaev, B.I.; Pastukhov, V.P.

    1994-05-01

    Experimental studies of nondissipative low frequency drift instability are reported; the plasma of a long mirror trap with edge casp anchors was investigated. The instability growth was found to take place only in a limited number of operation modes even in the case of all the growth requirements being satisfied. Furthermore, the instability development is rather moderate, and the associated anomalous losses appear to be small compared to the classical Coulomb losses. Possible factors accounting for the {open_quotes}soft{close_quotes} instability evolution are discussed. 13 refs., 6 figs.

  20. 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.

  1. Higgs instability in gapless superfluidity/superconductivity

    SciTech Connect

    Giannakis, Ioannis; Hou Defu; Huang Mei; Ren Haicang

    2007-01-01

    In this letter we explore the Higgs instability in the gapless superfluid/superconducting phase. This is in addition to the (chromo)magnetic instability that is related to the fluctuations of the Nambu-Goldstone bosonic fields. While the latter may induce a single-plane-wave Larkin-Ovchinnikov-Fulde-Ferrel state, the Higgs instability favors spatial inhomogeneity. In the case of the 2-flavor color superconductivity state the Higgs instability can only be partially removed by the electric Coulomb energy. But this does not exclude the possibility that it can be completely removed in other exotic states such as the gapless color-flavor locked state.

  2. Nonlinear longitudinal combustion instability in rocket motors.

    NASA Technical Reports Server (NTRS)

    Lores, M. E.; Zinn, B. T.

    1973-01-01

    A new analytical technique for the solution of nonlinear longitudinal combustion instability problems in rocket combustors is developed. Using relatively little computation time, this technique is capable of predicting the transient and limit cycle behavior of the combustion instability oscillations as well as the disturbance amplitude required to trigger an instability in a linearly stable motor. The limit cycle waveforms are found to exhibit shock wave characteristics for most unstable engine operating conditions. It is shown that the characteristics of the resulting instability are independent of the nature of the initial disturbance and they depend solely upon the engine operating conditions and the characteristics of the unsteady combustion process.

  3. 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.

  4. Anterior Tibial Translation in Collegiate Athletes with Normal Anterior Cruciate Ligament Integrity

    PubMed Central

    Rosene, John M.; Fogarty, Tracey D.

    1999-01-01

    Objective: To examine differences in anterior tibial translation (ATT) among sports, sex, and leg dominance in collegiate athletes with normal anterior cruciate ligament integrity. Design and Setting: Subjects from various athletic teams were measured for ATT in right and left knees. Subjects: Sixty subjects were measured for ATT with a KT-1000 knee arthrometer. Measurements: Statistical analyses were computed for each sex and included a 2 × 3 × 4 mixed-factorial analysis of variance (ANOVA) for anterior cruciate ligament displacement, right and left sides, and force and sport. A 2 × 2 × 3 mixed-factorial ANOVA was computed to compare means for sex and force. A 2 × 3 mixed-factorial ANOVA was computed to compare sex differences across 3 forces. Results: For males and females, no significant interactions were found among leg, force, and sport for mean ATT, for leg and sport or leg and force, or for translation values between dominant and nondominant legs. Males had a significant interaction for force and sport, and a significant difference was found for side of body, since the right side had less translation than the left side. Females had greater ATT than males at all forces. Conclusions: Sex differences exist for ATT, and differences in ATT exist among sports for both sexes. Differences between the right and left sides of the body should be expected when making comparisons of ligamentous laxity. ImagesFigure 2.Figure 3.Figure 5. PMID:16558565

  5. Temporal and spatial requirements for Nodal-induced anterior mesendoderm and mesoderm in anterior neurulation.

    PubMed

    Gonsar, Ngawang; Coughlin, Alicia; Clay-Wright, Jessica A; Borg, Bethanie R; Kindt, Lexy M; Liang, Jennifer O

    2016-01-01

    Zebrafish with defective Nodal signaling have a phenotype analogous to the fatal human birth defect anencephaly, which is caused by an open anterior neural tube. Previous work in our laboratory found that anterior open neural tube phenotypes in Nodal signaling mutants were caused by lack of mesendodermal/mesodermal tissues. Defects in these mutants are already apparent at neural plate stage, before the neuroepithelium starts to fold into a tube. Consistent with this, we found that the requirement for Nodal signaling maps to mid-late blastula stages. This timing correlates with the timing of prechordal plate mesendoderm and anterior mesoderm induction, suggesting these tissues act to promote neurulation. To further identify tissues important for neurulation, we took advantage of the variable phenotypes in Nodal signaling-deficient sqt mutant and Lefty1-overexpressing embryos. Statistical analysis indicated a strong, positive correlation between a closed neural tube and presence of several mesendoderm/mesoderm-derived tissues (hatching glands, cephalic paraxial mesoderm, notochord, and head muscles). However, the neural tube was closed in a subset of embryos that lacked any one of these tissues. This suggests that several types of Nodal-induced mesendodermal/mesodermal precursors are competent to promote neurulation. PMID:26528772

  6. [Large distal anterior cerebral artery aneurysm associated with azygos anterior cerebral artery: case report].

    PubMed

    Suzuki, Y; Kawamata, T; Matsumoto, H; Kunii, N; Matsumoto, K

    1998-10-01

    A 51-year-old woman presented with a distal anterior cerebral artery aneurysm (DACAA) manifesting as severe headache and monoparesis of the left lower limb. Computed tomography revealed subarachnoid hemorrhage in the interhemispheric fissure, bilateral sylvian fissures, and basal cistern, and a hematoma in the supracallosal region. Angiography showed a large aneurysm (23 x 18 mm) located on the distal end of the azygos anterior cerebral artery (azygos ACA) at the supracallosal portion. T2-weighted magnetic resonance imaging demonstrated the hematoma as a mixed intensity mass, compressing the corpus callosum downward, and the aneurysm as a flow void anterior to the hematoma. Unilateral frontoparietal parasagittal craniotomy was performed with a horse-shoe shaped incision. The aneurysm was clipped via the interhemispheric approach, and the hematoma was aspirated. Postoperative angiography showed disappearance of the aneurysm and intact azygos ACA. The patient was discharged with mild monoparesis, paresthesia of the left lower limb and diagnostic dyspraxia. DACAA almost always arises at or near the genu of the corpus callosum and is often associated with vascular anomaly. In the literature, 22 of 26 cases of large and giant DACAA were located at or near the genu, but only 3 cases, including ours, in the supracallosal area. 11 cases were associated with azygos ACA. Therefore, hemodynamic stress caused by vascular anomaly may be involved in the formation of large or giant DACAA in contrast with cases of normal DACAA. PMID:9789300

  7. Partial anterior cruciate ligament tears treated with intraligamentary plasma rich in growth factors

    PubMed Central

    Seijas, Roberto; Ares, Oscar; Cuscó, Xavier; Álvarez, Pedro; Steinbacher, Gilbert; Cugat, Ramón

    2014-01-01

    AIM: To evaluate the effect of the application of plasma rich in growth factors (PRGF)-Endoret to the remaining intact bundle in partial anterior cruciate ligament (ACL) tears. METHODS: A retrospective review of the rate of return to play in football players treated with the application of PRGF-Endoret in the remaining intact bundle in partial ACL injuries that underwent surgery for knee instability. Patients with knee instability requiring revision surgery for remnant ACL were selected. PRGF was applied in the wider part of posterolateral bundle and the time it took patients to return to their full sporting activities at the same level before the injury was evaluated. RESULTS: A total of 19 patients were reviewed. Three had a Tegner activity level of 10 and the remaining 16 level 9. The time between the injury and the time of surgery was 5.78 wk (SD 1.57). In total, 81.75% (16/19) returned to the same pre-injury level of sport activity (Tegner 9-10). 17 males and 2 females were treated. The rate of associated injury was 68.42% meniscal lesions and 26.31% cartilage lesions. The KT-1000 values were normalized in all operated cases. One patient was not able to return to sport due to the extent of their cartilage lesions. The 15 patients with Tegner activity level 9 returned to play at an average of 16.20 wk (SD 1.44) while the 3 patients with Tegner activity level 10 did so in 12.33 wk (SD 1.11). CONCLUSION: With one remaining intact bundle the application of PRGF-Endoret in instability cases due to partial ACL tear showed high return to sport rates at pre- injury level in professional football players. PMID:25035842

  8. Instability of a penetrating blade

    NASA Astrophysics Data System (ADS)

    Bigoni, D.; Bosi, F.; Dal Corso, F.; Misseroni, D.

    2014-03-01

    Application of a dead compressive load at the free end of an elastic rod (the ‘blade') induces its penetration into a sliding sleeve ending with a linear elastic spring. Bifurcation and stability analysis of this simple elastic system shows a variety of unexpected behaviors: (i) an increase of buckling load at decreasing of elastic stiffness; (ii) a finite number of buckling loads for a system with infinite degrees of freedom (leading to a non-standard Sturm-Liouville problem); (iii) more than one bifurcation load associated to each bifurcation mode; (iv) a restabilization of the straight configuration after the second bifurcation load associated to the first instability mode; (v) the presence of an Eshelby-like (or configurational) force, deeply influencing stability. Only the first of these behaviors was previously known, the second and third ones disprove common beliefs, the fourth highlights a sort of ‘island of instability', and the last one shows surprising phenomena and effects on stability.

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  13. 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

  14. 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.

  15. Prospects of ITER Instability Control

    NASA Astrophysics Data System (ADS)

    Kolemen, Egemen

    2015-11-01

    Prospects for real-time MHD stability analysis, plasma response calculations, and their use in ELM, NTM, RWM control and EFC will be discussed. ITER will need various controls to work together in order to achieve the stated goal of Q >= 10 for multiple minutes. These systems will allow operating at high beta while avoiding disruptions that may lead to damage to the reactor. However, it has not yet been demonstrated whether the combined real-time feedback control aim is feasible given the spectrum of plasma instabilities, the quality of the real-time diagnostic measurement/analysis, and the actuator set at ITER. We will explain challenges of instability control for ITER based on experimental and simulation results. We will demonstrate that it will not be possible to parameterize all possible disruption avoidance and ramp down scenarios that ITER may encounter. An alternative approach based on real-time MHD stability analysis and plasma response calculations, and its use in ELM, NTM, RWM control and EFC, will be demonstrated. Supported by the US DOE under DE-AC02-09CH11466.

  16. 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.

  17. Electrokinetic instability of isotachophoresis shocks

    NASA Astrophysics Data System (ADS)

    Garcia, Giancarlo; Santiago, Juan; Mani, Ali

    2013-11-01

    Isotachophoresis (ITP) is an electrokinetic focusing technique used in a variety of life science and analytical chemistry applications. In ITP, an electrokinetic shock wave forms at the interface between leading and trailing electrolytes with relatively high and low conductivities. The ITP interface is self-sharpening, as restoring electromigration fluxes counteract molecular diffusion. However, the large electric field gradient at the shock interface also gives rise to free charge and strong electrostatic body forces. At large applied currents, electrostatic forces cause recirculating flows which destabilize the ITP interface. We performed stability analysis and direct simulation of ITP shocks through numerical solutions to the coupled Nernst-Planck and Navier-Stokes equations using a quasi-electroneutral approximation. In both experiments and numerical simulations, we observe two modes of instability: 1) a distorted ITP interface which is steady in time, and 2) an oscillating perturbation which persists. In addition, at the highest simulated electric fields, we observe transition towards more chaotic oscillatory modes. We use our stability analysis and numerical simulations to characterize instability of ITP shocks using two dimensionless parameters.

  18. Instabilities in fluorocarbon ICP plasmas

    NASA Astrophysics Data System (ADS)

    Booth, Jean-Paul; Abada, Hana

    2000-10-01

    Several recent studies (Lieberman and al(M. A. Lieberman, A. J. Lichtenberg and A. M. Marakhtanov, App. Phys. Vol75,3617 (1999)), Tuszewski(M. Tuszewski, J. Appl. Phys. 79, 8967 (1996))) have shown the presence of instabilities in low pressure inductively coupled discharges with electronegative gases (O_2, Ar/SF_6). Lieberman and al^1 have proposed an explanation for this effect in terms of electon attachment processes causing an oscillation between capacitive and inductive coupling modes. We have observed similar instabilities in ICP fluorocarbon plasmas (CF_4, C_2F_6, CHF_3) by observing the optical emission from the plasma. In CF4 plasmas, the optical emission is modulated by up to 90% at frequencies 200-1 kHz at 1-20 mtorr with rf powers of 300 W and 500W. We have also observed an interesting phenomenon whereby inductive/capacitive oscillations occur during several hundreds of ms, in between periods of stable capactive operation lasting several hudreds of ms.

  19. Coriolis instability of pulsed flow

    NASA Astrophysics Data System (ADS)

    Aouidef, A.; Normand, C.; Wesfreid, J. E.

    1995-09-01

    The linear stability of a time-periodic flow is considered. The fluid motion is taking place in a Hele-Shaw cell made of two vertical rectangular parallel plates separated by a gap of small extent compared to the dimensions of the plates. The flow is generated by oscillating the cell about its vertical symmetry axis. Our stability analysis was motivated by the experimental results reported some years ago by Bolton and Maurer [Bull. Am. Phys. Soc. 32, 2097 (1987)] who observed the onset of longitudinal rolls in this configuration. The inviscid stability criterion for steady flow subjected to Coriolis force is applied at different times to assess the instability mechanism in the two opposite regimes of respectively low and high frequency of oscillation. For moderate values of the frequency, implementation of Floquet theory is used to find the critical values of the instability parameters. Finally a connection is established between the present results and those we obtained recently for a pulsed flow in a Taylor-Couette geometry.

  20. 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.

  1. The in vivo kinematics of the tibiotalar joint after lateral ankle instability

    PubMed Central

    Caputo, Adam M.; Lee, Jun Y.; Spritzer, Chuck E.; Easley, Mark E.; DeOrio, James K.; Nunley, James A.; DeFrate, Louis E.

    2010-01-01

    BACKGROUND Previous studies have suggested injury to the anterior talofibular ligament may be linked to altered kinematics and the development of osteoarthritis of the ankle joint. However, the effects of ATFL injury on the in vivo kinematics of the ankle joint are unclear. HYPOTHESIS Based on the orientation of the ATFL fibers, we hypothesized that ATFL deficiency would lead to increased anterior translation and increased internal rotation of the talus relative to the tibia. STUDY DESIGN Controlled laboratory study. METHODS The ankles of 9 patients with unilateral ATFL injuries were compared as they stepped onto a level surface. Kinematic measurements were made as a function of increasing load. Using magnetic resonance imaging and orthogonal fluoroscopy, the in vivo kinematics of the tibiotalar joint were measured in the ATFL deficient and intact ankles from the same individuals. RESULTS A statistically significant increase in internal rotation, anterior translation, and superior translation of the talus was measured in ATFL deficient ankles as compared to intact, contralateral controls. For example, at 100% body weight, ATFL deficient ankles demonstrated a statistically significant increase in anterior translation of 0.9 ± 0.5mm (p = 0.008). At 100% body weight, the ATFL deficient ankle was internally rotated relative to the intact ankle by 5.7 ± 3.6° (p = 0.008). There was a slight increase of 0.2 ± 0.2mm in the superior translation of the ATFL deficient ankle compared to the intact ankle at 100% body weight (p = 0.02). CONCLUSIONS ATFL deficiency increases anterior translation, internal rotation, and superior translation of the talus. CLINICAL RELEVANCE Altered kinematics may contribute to the degenerative changes observed with chronic lateral ankle instability. These findings might help to explain the degenerative changes frequently observed on the medial talus in patients with chronic ATFL insufficiency and provide a baseline for improving ankle ligament

  2. Method for measuring anterior chamber volume by image analysis

    NASA Astrophysics Data System (ADS)

    Zhai, Gaoshou; Zhang, Junhong; Wang, Ruichang; Wang, Bingsong; Wang, Ningli

    2007-12-01

    Anterior chamber volume (ACV) is very important for an oculist to make rational pathological diagnosis as to patients who have some optic diseases such as glaucoma and etc., yet it is always difficult to be measured accurately. In this paper, a method is devised to measure anterior chamber volumes based on JPEG-formatted image files that have been transformed from medical images using the anterior-chamber optical coherence tomographer (AC-OCT) and corresponding image-processing software. The corresponding algorithms for image analysis and ACV calculation are implemented in VC++ and a series of anterior chamber images of typical patients are analyzed, while anterior chamber volumes are calculated and are verified that they are in accord with clinical observation. It shows that the measurement method is effective and feasible and it has potential to improve accuracy of ACV calculation. Meanwhile, some measures should be taken to simplify the handcraft preprocess working as to images.

  3. Magnetic resonance imaging artifact following anterior cervical discectomy and fusion with a trabecular metal cage.

    PubMed

    Elliott, Cameron A; Fox, Richard; Ashforth, Robert; Gourishankar, Sita; Nataraj, Andrew

    2016-03-01

    OBJECT This study was undertaken to evaluate the impact of postoperative MRI artifact on the assessment of ongoing spinal cord or nerve root compression after anterior cervical discectomy and fusion (ACDF) using a trabecular tantalum cage or bone autograft or allograft. METHODS The authors conducted a retrospective review of postoperative MRI studies of patients treated surgically for cervical disc degenerative disease or cervical instability secondary to trauma. Standard ACDF with either a trabecular tantalum cage or interbody bone graft had been performed. Postoperative MR images were shown twice in random order to each of 3 assessors (2 spine surgeons, 1 neuroradiologist) to determine whether the presence of a tantalum interbody cage and/or anterior cervical fixation plate or screws imparted MRI artifact significant enough to prevent reliable postoperative assessment of ongoing spinal cord or nerve root compression. RESULTS A total of 63 patients were identified. One group of 29 patients received a tantalum interbody cage, with 13 patients (45%) undergoing anterior plate fixation. A second group of 34 patients received bone auto- or allograft, with 23 (68%) undergoing anterior plate fixation. The paramagnetic implant construct artifact had minimal impact on visualization of postoperative surgical level spinal cord compression. In the cage group, 98% (171/174) of the cases were rated as assessable versus 99% in the bone graft group (201/204), with high intraobserver reliability. In contrast, for the assessment of ongoing surgical level nerve root compression, the presence of a tantalum cage significantly decreased visualization of nerve roots to 70% (121/174) in comparison with 85% (173/204) in the bone graft group (p < 0.001). When sequences using turbo spin echo (TSE), a T2-weighted axial sequence, were acquired, nerve roots were rated as assessable in 88% (69/78) of cases; when only axial T2-weighted sequences were available, the nerve roots were rated as

  4. Anterior commissure versus corpus callosum: A quantitative comparison across mammals.

    PubMed

    Ashwell, Ken W S

    2016-04-01

    Mammals rely on two major pathways to transfer information between the two hemispheres of the brain: the anterior commissure and the corpus callosum. Metatheria and monotremes rely exclusively on the anterior commissure for interhemispheric transfer between the isocortices and olfactory allocortices of each side, whereas Eutheria use a combination of the anterior commissure and an additional pathway exclusive to Eutheria, the corpus callosum. Midline cross-sectional area of the anterior commissure and corpus callosum were measured in a range of mammals from all three infraclasses and plotted against brain volume to determine how midline anterior commissure area and its size relative to the corpus callosum vary with brain size and taxon. In Metatheria, the square root of anterior commissure area rises in almost direct proportion with the cube root of brain volume (i.e. the ratio of the two is relatively constant), whereas among Eutheria the ratio of the square root of anterior commissure area to the cube root of brain volume declines slightly with increasing brain size. The total of isocortical and olfactory allocortical commissure area rises more rapidly with increasing brain volume among Eutheria than among Metatheria. This means that the midline isocortical and olfactory allocortical commissural area of metatherians with large brains (about 70 ml) is only about 50% of that among eutherians with similarly sized brains. On the other hand, isocortical and olfactory allocortical commissural area is similar in Metatheria and Eutheria at brain volumes around 1 ml. Among the Eutheria, some groups make less use of the anterior commissure pathway than do others: soricomorphs, rodents and cetaceans have smaller anterior commissures for their brain size than do afrosoricids, erinaceomorphs and proboscideans. The findings suggest that use of the anterior commissural route for isocortical commissural connections may have placed limitations on interhemispheric transfer of

  5. Top-Down Dysregulation—From ADHD to Emotional Instability

    PubMed Central

    Petrovic, Predrag; Castellanos, F. Xavier

    2016-01-01

    Deficient cognitive top-down executive control has long been hypothesized to underlie inattention and impulsivity in attention-deficit/hyperactivity disorder (ADHD). However, top-down cognitive dysfunction explains a modest proportion of the ADHD phenotype whereas the salience of emotional dysregulation is being noted increasingly. Together, these two types of dysfunction have the potential to account for more of the phenotypic variance in patients diagnosed with ADHD. We develop this idea and suggest that top-down dysregulation constitutes a gradient extending from mostly non-emotional top-down control processes (i.e., “cool” executive functions) to mainly emotional regulatory processes (including “hot” executive functions). While ADHD has been classically linked primarily to the former, conditions involving emotional instability such as borderline and antisocial personality disorder are closer to the other. In this model, emotional subtypes of ADHD are located at intermediate levels of this gradient. Neuroanatomically, gradations in “cool” processing appear to be related to prefrontal dysfunction involving dorsolateral prefrontal cortex (dlPFC) and caudal anterior cingulate cortex (cACC), while “hot” processing entails orbitofrontal cortex and rostral anterior cingulate cortex (rACC). A similar distinction between systems related to non-emotional and emotional processing appears to hold for the basal ganglia (BG) and the neuromodulatory effects of the dopamine system. Overall we suggest that these two systems could be divided according to whether they process non-emotional information related to the exteroceptive environment (associated with “cool” regulatory circuits) or emotional information related to the interoceptive environment (associated with “hot” regulatory circuits). We propose that this framework can integrate ADHD, emotional traits in ADHD, borderline and antisocial personality disorder into a related cluster of mental

  6. Top-Down Dysregulation-From ADHD to Emotional Instability.

    PubMed

    Petrovic, Predrag; Castellanos, F Xavier

    2016-01-01

    Deficient cognitive top-down executive control has long been hypothesized to underlie inattention and impulsivity in attention-deficit/hyperactivity disorder (ADHD). However, top-down cognitive dysfunction explains a modest proportion of the ADHD phenotype whereas the salience of emotional dysregulation is being noted increasingly. Together, these two types of dysfunction have the potential to account for more of the phenotypic variance in patients diagnosed with ADHD. We develop this idea and suggest that top-down dysregulation constitutes a gradient extending from mostly non-emotional top-down control processes (i.e., "cool" executive functions) to mainly emotional regulatory processes (including "hot" executive functions). While ADHD has been classically linked primarily to the former, conditions involving emotional instability such as borderline and antisocial personality disorder are closer to the other. In this model, emotional subtypes of ADHD are located at intermediate levels of this gradient. Neuroanatomically, gradations in "cool" processing appear to be related to prefrontal dysfunction involving dorsolateral prefrontal cortex (dlPFC) and caudal anterior cingulate cortex (cACC), while "hot" processing entails orbitofrontal cortex and rostral anterior cingulate cortex (rACC). A similar distinction between systems related to non-emotional and emotional processing appears to hold for the basal ganglia (BG) and the neuromodulatory effects of the dopamine system. Overall we suggest that these two systems could be divided according to whether they process non-emotional information related to the exteroceptive environment (associated with "cool" regulatory circuits) or emotional information related to the interoceptive environment (associated with "hot" regulatory circuits). We propose that this framework can integrate ADHD, emotional traits in ADHD, borderline and antisocial personality disorder into a related cluster of mental conditions. PMID:27242456

  7. Missile injuries of the anterior skull base.

    PubMed

    Bhatoe, Harjinder Singh

    2004-02-01

    Missile injuries of the anterior skull base usually occur during war or war-like situations. These injuries may be isolated or associated with multiple traumatic injuries. We report 23 such cases managed during military conflicts and peacekeeping operations. All were adult males. Four of these patients sustained bullet injuries; the rest were injured from shrapnel. Eighteen patients had injury to the visual apparatus with permanent blindness. Proptosis was seen in 16, cerebrospinal fluid (CSF) leak from the wound in seven, and CSF orbitorrhea in three patients. Sixteen had irreparable injury to the eye necessitating evisceration/enucleation, and two had retrobulbar optic nerve injury. Three patients were comatose [Glasgow Coma Scale (GCS) 3/15], and 14 had altered sensorium. Six patients were fully conscious. All were investigated by computed tomography (CT), which revealed injury to the eyeball and skull base, orbital fracture, frontal hematoma, contusion, and pneumocephalus. Seventeen patients underwent emergency surgery, and six patients were initially managed conservatively. Neurosurgical management consisted of making bifrontal flaps, craniotomy/craniectomy, debridement, and repair of the base with fascia lata. Reconstruction of the orbital rim was required in three cases. All were managed postoperatively with cerebral decongestants and antibiotics in anti-meningitic dosages. There was one death in the postoperative period; outcome was good in 16 and moderate in four patients. Twelve patients had retained intracranial splinters; three of these developed recurrent suppurative meningitis. Of the six patients initially managed conservatively, three were subsequently operated for CSF rhinorrhea. Gross communition, dural loss, and injury to the frontal scalp often preclude the use of pericranial repair of the skull base. Fascia lata is extremely useful for reconstruction and repair. Anterior cranial fossa injury probably carries a better prognosis; however, there

  8. A biomechanical analysis of anterior load carriage.

    PubMed

    Anderson, A M; Meador, K A; McClure, L R; Makrozahopoulos, D; Brooks, D J; Mirka, G A

    2007-12-01

    Front load carriage is a common occupational task in some industries (e.g. agriculture, construction), but, as compared to lifting tasks, relatively little research has been conducted on the biomechanical loading during these activities. The focus of this study was to explore the low back biomechanics during these activities and, specifically, to examine the effects of load height and walking speed on trunk muscle activity and trunk posture. Eleven male participants participated in two separate front load-carriage experiments. The first experiment called for carrying a barbell (with weight corresponding to 20% of elbow flexion strength) at three heights (knuckle height, elbow height and shoulder height) at a constant horizontal distance from the spine. The second experiment called for participants to carry a bucket of potatoes weighing 14 kg at the same three heights, but with no further restrictions in technique. In both experiments, the participants performed this task while either standing still or walking at a self-selected speed. As they performed these tasks, the activity levels of the right-side muscle of the rectus abdominis, external oblique, biceps brachii, anterior deltoid and three levels (T9, T12 and L3) of the erector spinae were sampled. Mid-sagittal plane trunk posture was also quantified using three magnetic field-based motion sensors at T9, T12 and L3. The results showed a significant effect of both walking speed and load height on trunk posture and trunk muscle activity levels in both the barbell and bucket experiments. In the barbell experiment, the walking trials generated 43% more trunk muscle activity than the standing trials. Trials at shoulder height produced 11% more muscle activity than trials at elbow height in the T9 erector spinae muscles and 71% more muscle activity in the anterior deltoid. In the bucket experiment, trunk muscle activity responded in a similar fashion, but the key result here was the quantification of the natural

  9. 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

  10. 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

  11. Laboratory blast wave driven instabilities

    NASA Astrophysics Data System (ADS)

    Kuranz, Carolyn

    2008-04-01

    This presentation discusses experiments well-scaled to the blast wave driven instabilities during the explosion phase of SN1987A. Blast waves occur following a sudden, finite release of energy, and consist of a shock front followed by a rarefaction wave. When a blast wave crosses an interface with a decrease in density, hydrodynamic instabilities will develop. These experiments include target materials scaled in density to the He/H layer in SN1987A. About 5 kJ of laser energy from the Omega Laser facility irradiates a 150 μm plastic layer that is followed by a low density foam layer. A blast wave structure similar to those in supernovae, is created in the plastic layer. The blast wave crosses a perturbed interface, which produces nonlinear, unstable growth dominated by the Rayleigh-Taylor (RT) instability. Recent experiments have been performed using complex initial conditions featuring a three-dimensional interface structure with a wavelength of 71 μm in two orthogonal directions, at times supplemented by an additional sinusoidal mode of 212 μm or 424 μm. We have detected the interface structure under these conditions, using dual orthogonal radiographs on some shots, and will show some of the resulting data. Recent advancements in our x-ray backlighting techniques have greatly improved the resolution of our x-ray radiographic images. Under certain conditions, the improved images show some mass extending beyond the RT spike and penetrating further than previously observed. Current simulations do not show this phenomenon. This presentation will discuss the amount of mass in these spike extensions as well as the error analysis of this calculation. Future experiments will also be discussed. They will be focusing on realistic initial conditions based on 3D stellar evolution models. This research was sponsored by the Stewardship Science Academic Alliances Program through DOE Research Grants DE-FG52-07NA28058, DE-FG52-04NA00064, and other grants and contracts.

  12. Electric Field Induced Interfacial Instabilities

    NASA Technical Reports Server (NTRS)

    Kusner, Robert E.; Min, Kyung Yang; Wu, Xiao-lun; Onuki, Akira

    1999-01-01

    The study of the interface in a charge-free, 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 this paper, the flat interface of a marginally polar binary fluid mixture is stressed by a perpendicular alternating electric field and the resulting instability is characterized by the critical electric field E(sub c) and the pattern observed. The character of the surface dynamics at the onset of instability is found to be strongly dependent on the frequency f of the field applied. The plot of E(sub c) vs. f for a fixed temperature shows a sigmoidal shape, whose low and high frequency limits are well described by a power-law relationship, E(sub c) = epsilon(exp zeta) with zeta = 0.35 and zeta = 0.08, respectively. The low-limit exponent compares well with the value zeta = 4 for a system of conducting and non-conducting fluids. On the other hand, the high-limit exponent coincides with what was first predicted by Onuki. The instability manifests itself as the conducting phase penetrates the non-conducting phase. As the frequency increases, the shape of the pattern changes from an array of bifurcating strings to an array of column-like (or rod-like) protrusions, each of which spans the space between the plane interface and one of the electrodes. For an extremely high frequency, the disturbance quickly grows into a parabolic cone pointing toward the upper plate. As a result, the interface itself changes its shape from that of a plane to that of a high sloping pyramid.

  13. Anterior Glenoid Rim Fracture Following Use of Resorbable Devices for Glenohumeral Stabilization

    PubMed Central

    Augusti, Carlo Alberto; Paladini, Paolo; Campi, Fabrizio; Merolla, Giovanni; Bigoni, Marco; Porcellini, Giuseppe

    2015-01-01

    Background Resorbable anchors are widely used in arthroscopic stabilization of the shoulder as a means of soft tissue fixation to bone. Their function is to ensure repair stability until they are replaced by host tissue. Complications include inflammatory soft tissue reactions, cyst formation, screw fragmentation in the joint, osteolytic reactions, and enhanced glenoid rim susceptibility to fracture. Purpose To evaluate resorption of biodegradable screws and determine whether they induce formation of areas with poor bone strength that may lead to glenoid rim fracture even with minor trauma. Study Design Case series; Level of evidence, 4. Methods This study evaluated 12 patients with anterior shoulder instability who had undergone arthroscopic stabilization with the Bankart technique and various resorbable anchors and subsequently experienced redislocation. The maximum interval between arthroscopic stabilization and the new dislocation was 52 months (mean, 22.16 months; range, 12-52 months). The mean patient age was 31.6 years (range, 17-61 years). The persistence or resorption of anchor holes; the number, area, and volume of osteolytic lesions; and glenoid erosion/fracture were assessed using computed tomography scans taken after redislocation occurred. Results Complete screw resorption was never documented. Osteolytic lesions were found at all sites (mean diameter, 5.64 mm; mean depth, 8.09 mm; mean area, 0.342 cm2; mean volume, 0.345 cm3), and all exceeded anchor size. Anterior glenoid rim fracture was seen in 9 patients, even without high-energy traumas (75% of all recurrences). Conclusion Arthroscopic stabilization with resorbable devices is a highly reliable procedure that is, however, not devoid of complications. In all 12 patients, none of the different implanted anchors had degraded completely, even in patients with longer follow-up, and all induced formation of osteolytic areas. Such reaction may lead to anterior glenoid rim fracture according to the

  14. Arthroscopic Distal Clavicular Autograft for Treating Shoulder Instability With Glenoid Bone Loss

    PubMed Central

    Tokish, John M.; Fitzpatrick, Kelly; Cook, Jay B.; Mallon, William J.

    2014-01-01

    Glenoid bone loss is a significant risk factor for failure after arthroscopic shoulder stabilization. Multiple options are available to reconstruct this bone loss, including coracoid transfer, iliac crest bone graft, and osteoarticular allograft. Each technique has strengths and weaknesses. Coracoid grafts are limited to anterior augmentation and, along with iliac crest, do not provide an osteochondral reconstruction. Osteochondral allografts do provide a cartilage source but are challenged by the potential for graft rejection, infection, cost, and availability. We describe the use of a distal clavicular osteochondral autograft for bony augmentation in cases of glenohumeral instability with significant bone loss. This graft has the advantages of being readily available and cost-effective, it provides an autologous osteochondral transplant with minimal donor-site morbidity, and it can be used in both anterior and posterior bone loss cases. The rationale and technical aspects of arthroscopic performance will be discussed. Clinical studies are warranted to determine the outcomes of the use of the distal clavicle as a graft in shoulder instability. PMID:25264509

  15. Anterior Cervical Discectomy and Fusion (ACDF): Comparison Between Zero Profile Implants and Anterior Cervical Plate and Spacer

    PubMed Central

    Alimi, Marjan; Njoku, Innocent; Hofstetter, Christoph P; Tsiouris, Apostolos J; Kesavabhotla, Kartik; Boockvar, John; Härtl, Roger

    2016-01-01

    Introduction: Interposition grafts combined with anterior plating currently remain the gold standard for anterior cervical discectomy and fusion. The use of anterior plates increases fusion rates but may be associated with higher rates of postoperative dysphagia. The aim of the current study was to determine the clinical and radiological outcomes following anterior cervical discectomy and fusion (ACDF) using zero-profile anchored spacers versus standard interposition grafts with anterior plating. Methods: This was a retrospective case series. A total of 53 male and 51 female consecutive patients (164 total operated levels) who underwent ACDF between 2007 and 2011 were included. The mean clinical follow-up was 15.7 ± 1.2 (SEM) months for patients with zero-profile implants and 14.8 ± 2.1 months for patients with conventional ACDF with anterior plating. Patient demographics, operative details, clinical outcomes, complications, and radiographic imaging were reviewed. Dysphagia was determined using the Bazaz criteria. Results: Clinical outcome scores improved in both groups as measured by the modified Japanese Orthopedic Association and Nurick scores. Zero-profile constructs gave rise to significantly less prevertebral soft tissue swelling compared to constructs with anterior plates postoperatively (15.74 ± 0.52 as compared to 20.48 ± 0.85 mm, p < 0.001) and at the latest follow-up (10.88 ± 0.39 mm vs. 13.72 ± 0.67 mm, p < 0.001). There was a significant difference in the incidence of dysphagia at the latest follow-up (1.5% vs. 20%, p=0.001, zero-profile vs. anterior plate, respectively). Conclusion: Zero-profile implants lead to functional outcomes similar to standard anterior plate constructs. Avoiding the use of an anterior locking plate may decrease the risk of persistent postoperative dysphagia. PMID:27200226

  16. Beam Dynamics and Instabilities in MEIC Design

    SciTech Connect

    S. Ahmed, G.A. Krafft, B.C. Yunn

    2011-03-01

    In this paper, we study the narrow and broadband impedance calculations and various instabilities generated by single and multiple bunches. We study the physical phenomena such as intra-beam scattering, touschek scattering, beam-gas scattering, ion trapping and fast beam-ion instability, etc. Details will be discussed in the paper.

  17. Multiscale instabilities in soft heterogeneous dielectric elastomers

    PubMed Central

    Rudykh, S.; Bhattacharya, K.; deBotton, G.

    2014-01-01

    The development of instabilities in soft heterogeneous dielectric elastomers is investigated. Motivated by experiments and possible applications, we use in our analysis the physically relevant referential electric field instead of electric displacement. In terms of this variable, a closed form solution is derived for the class of layered neo-Hookean dielectrics. A criterion for the onset of electromechanical multiscale instabilities for the layered composites with anisotropic phases is formulated. A general condition for the onset of the macroscopic instability in soft multiphase dielectrics is introduced. In the example of the layered dielectrics, the essential influence of the microstructure on the onset of instabilities is revealed. We found that: (i) macroscopic instabilities dominate at moderate volume fractions of the stiffer phase, (ii) interface instabilities appear at small volume fractions of the stiffer phase and (iii) instabilities of a finite scale, comparable to the microstructure size, occur at large volume fractions of the stiffer phase. The latest new type of instabilities does not appear in the purely mechanical case and dominates in the region of large volume fractions of the stiff phase. PMID:24511258

  18. Ion-cyclotron instability in magnetic mirrors

    SciTech Connect

    Pearlstein, L.D.

    1987-02-02

    This report reviews the role of ion-cyclotron frequency instability in magnetic mirrors. The modes discussed here are loss-cone or anisotropy driven. The discussion includes quasilinear theory, explosive instabilities of 3-wave interaction and non-linear Landau damping, and saturation due to non-linear orbits. (JDH)

  19. Single bunch instabilities of the RHIC booster

    SciTech Connect

    Ng, K.Y.

    1986-02-01

    In this paper, we try to estimate the stability limits and impedances of the Brookhaven RHIC booster. Some important data on the booster are shown. From the stability limits and impedances, it is clear that the booster is safe against either fast microwave instabilities or slow mode-colliding single bunch instabilities. 4 figs., 5 tabs.

  20. Cultural diversity, economic development and societal instability

    USGS Publications Warehouse

    Nettle, D.; Grace, J.B.; Choisy, M.; Cornell, H.V.; Guegan, J.-F.; Hochberg, M.E.

    2007-01-01

    Background. Social scientists have suggested that cultural diversity in a nation leads to societal instability. However, societal instability may be affected not only by within-nation on ?? diversity, but also diversity between a nation and its neighbours or ?? diversity. It is also necessary to distinguish different domains of diversity, namely linguistic, ethnic and religious, and to distinguish between the direct effects of diversity on societal instability, and effects that are mediated by economic conditions. Methodology/Principal Findings. We assembled a large cross-national dataset with information on ?? and ?? cultural diversity, economic conditions, and indices of societal instability. Structural equation modeling was used to evaluate the direct and indirect effects of cultural diversity on economics and societal stability. Results show that different type and domains of diversity have interacting effects. As previously documented, linguistic ?? diversity has a negative effect on economic performance, and we show that it is largely through this economic mechanism that it affects societal instability. For ?? diversity, the higher the linguistic diversity among nations in a region, the less stable the nation. But, religious ?? diversity has the opposite effect, reducing instability, particularly in the presence of high linguistic diversity. Conclusions. Within-nation linguistic diversity is associated with reduced economic performance, which, in turn, increases societal instability. Nations which differ linguistically from their neighbors are also less stable. However, religious diversity between, neighboring nations has the opposite effect, decreasing societal instability.

  1. Instability of a constrained pendulum system

    NASA Astrophysics Data System (ADS)

    Ramachandran, Prashanth; Krishna, Srinivas Gopal; Ram, Y. M.

    2011-04-01

    Linear perturbation analysis is used to determine the natural frequency of two pendulums connected by a rod. The analysis indicates a zone of instability in what looks like a stable system. The paradoxical phenomenon is explained, and a simple experiment confirms the instability.

  2. Superresonant instability of a compressible hydrodynamic vortex

    NASA Astrophysics Data System (ADS)

    Oliveira, Leandro A.; Cardoso, Vitor; Crispino, Luís C. B.

    2016-06-01

    We show that a purely circulating and compressible system, in an adiabatic regime of acoustic propagation, presents superresonant instabilities. To show the existence these instabilities, we compute the quasinormal mode frequencies of this system numerically using two different frequency domain methods.

  3. Estimating the instability of a composite clock

    NASA Technical Reports Server (NTRS)

    Greenhall, Charles A.

    2004-01-01

    A composite clock created from a local clock ensemble is known by its time offsets from the ensemble clocks. By a geometrical argument, estimate for the instability of the composite clock are calculated from the instabilities of the ensemble clocks, individually and against the composite clock. The method is illustrated by examples using simulated and real ensembles.

  4. Principles of postoperative anterior cruciate ligament rehabilitation

    PubMed Central

    Saka, Tolga

    2014-01-01

    It is known that anterior cruciate ligament (ACL) reconstruction needs to be combined with detailed postoperative rehabilitation in order for patients to return to their pre-injury activity levels, and that the rehabilitation process is as important as the reconstruction surgery. Literature studies focus on how early in the postoperative ACL rehabilitation period rehabilitation modalities can be initiated. Despite the sheer number of studies on this topic, postoperative ACL rehabilitation protocols have not been standardized yet. Could common, “ossified” knowledge or modalities really prove themselves in the literature? Could questions such as “is postoperative brace use really necessary?”, “what are the benefits of early restoration of the range of motion (ROM)?”, “to what extent is neuromuscular electrical stimulation (NMES) effective in the protection from muscular atrophy?”, “how early can proprioception training and open chain exercises begin?”, “should strengthening training start in the immediate postoperative period?” be answered for sure? My aim is to review postoperative brace use, early ROM restoration, NMES, proprioception, open/closed chain exercises and early strengthening, which are common modalities in the very comprehensive theme of postoperative ACL rehabilitation, on the basis of several studies (Level of Evidence 1 and 2) and to present the commonly accepted ways they are presently used. Moreover, I have presented the objectives of postoperative ACL rehabilitation in tables and recent miscellaneous studies in the last chapter of the paper. PMID:25232521

  5. Reconstruction of the anterior cruciate ligament.

    PubMed

    Seedhom, B B

    1992-01-01

    Ligaments are strong collagenous structures that act as constraints on joint motion, thus confining the articular surfaces to more or less the same paths. In so doing they prevent arbitrary apposition of these surfaces from occurring and resulting in abnormal stresses which may damage the joint surfaces. Ligaments rupture due to excessive loads, particularly those resulting from trauma occurring during sporting events or motor vehicle accidents. Knee and ankle joints have the highest frequency of ligamentous injuries. This paper is a brief review of the current approaches to the reconstruction of the knee ligaments with specific reference to the anterior cruciate ligament (ACL) being the most frequently reconstructed. This is not only because it is frequently injured but also because of the debilitating consequences of such an injury. Approaches ranging from the conservative to those that advocate the use of frank prosthetic replacement have been adopted by surgeons at both ends of the spectrum. Following a discussion of the rationale for reconstruction of the ACL, the mechanical and biological considerations of the reconstructive procedure are discussed. The different methods of ACL reconstruction are reviewed. These include: (a) primary repair, (b) reconstruction with different tissues, including autogenous allografts and xenografts, (c) reconstruction employing different synthetic devices. A brief discussion of the procedures used for reconstruction with different types of tissue and of the surviving examples of the synthetic devices will follow. PMID:1418190

  6. Anterior Displacement of the Geniculate Ganglion.

    PubMed

    Tachibana, Tomoyasu; Orita, Yorihisa; Nishizaki, Kazunori

    2016-04-01

    We present the case of a 34-year-old Japanese woman with cholesteatoma of the middle ear. During the operation, this patient showed an unusual position of the geniculate ganglion. We reviewed the computed tomography (CT) images targeting the ear of the present case after the operation. We found that the shortest ranges from the ampullated end of the superior semicircular canal to the geniculate ganglion fossa were 5.1 mm on both sides. We did not find any cases with obvious dislocation of the geniculate ganglion among the 67 cases for which we had performed tympanoplasty. Displacement of the geniculate ganglion is either extremely rare or typically unnoticed because this abnormality is asymptomatic. We speculated that the unusual position of the geniculate ganglion was due to an incomplete development of the tympanic tegmen. When surgical treatment such as decompression of the facial nerve or tympanoplasty is performed, close attention should always be paid to the anatomy of the facial nerve from the labyrinthine segment to the geniculate ganglion. In the present case, although connective tissues existed around the anterior epitympanic recess, we left this lesion to avoid iatrogenic facial palsy. PMID:27340996

  7. Anterior cruciate ligament surgery in the rabbit

    PubMed Central

    2013-01-01

    Background Various methods regarding allograft knee replacements have been described. The animal models, which are generally used for this purpose include sheep, dogs, goats, and pigs, and accrue significant costs for study protocols. The authors herein describe an efficient and cost-effective model to study either native or tissue-engineered allografts for anterior cruciate ligament (ACL) replacement in a New Zealand rabbit model with the potential for transgenic and cell migration studies. Methods ACL reconstructions were performed in rabbits under general anesthesia. For fresh allograft implantations, two animals were operated in parallel. Each right extensor digitorum longus tendon was harvested and prepared for implantation. After excision of the ACL, tibial and femoral bone tunnels were created to implant each graft in the native ACL position. Results During a 2-year period, the authors have successfully undertaken this surgery in 61 rabbits and have not noticed any major complications attributed to this surgical technique. In addition, the authors have observed fast recovery in the animals postoperatively. Conclusion The authors recommend this surgical procedure as an excellent model for the study of knee surgery. PMID:23957941

  8. Anterior Inferior Iliac Spine Avulsion Fracture

    PubMed Central

    Serbest, Sancar; Tosun, Hacı Bayram; Tiftikçi, Uğur; Oktas, Birhan; Kesgin, Engin

    2015-01-01

    Abstract Avulsion fractures of the pelvic apophyses rarely occur in adolescent athletes in the course of sudden strong contraction of muscle attached to growth cartilage. This injury may usually be misdiagnosed for tendon or muscle strain. Patient's history, physical examination, and radiologic studies are important for diagnosis. The literature includes only a few case reports but no case series as yet. The aim of this study was to present the results of 5 cases of anterior inferior iliac spine (AIIS) avulsion fractures treated conservatively. The study included 5 patients (4 male, 1 female, mean age 13.6 years) who underwent conservative treatment for AIIS avulsion fractures and had an adequate follow-up. All patients were admitted to the emergency department and misdiagnosed as muscle strain. Three of them were football player, 1 skier, and 1 fighter. Each patient was treated with immobilization and nonsteroidal anti-inflammatory drugs. At follow-up, all patients showed relief from their pain and mechanical symptoms and regained full range of motion and returned to their previous levels of activity. Diagnosis requires careful attention to the physical examination and imaging. In this series, all pelvic avulsion fractures (100%) were managed successfully with a conservative approach. Good results and return to previous levels of activity can be achieved with conservative treatment. PMID:25700329

  9. Suturing a tear of the anterior capsulorhexis

    PubMed Central

    Kleinmann, G; Chew, J; Apple, D J; Assia, E I; Mamalis, N

    2006-01-01

    Aim To describe a new technique of suturing a tear in the anterior capsulorhexis. Methods Continuous curvilinear capsulorhexis (CCC) with lens removal was done in five fresh cadaver eyes. The diameter of the CCC was measured with a calliper. Using the same calliper a tear of the CCC was created while opening the calliper's arms. The distance between the calliper's arms needed to tear the CCC was documented. Using 9‐0 Ethilon 9011, CS 160‐6 sutures in two eyes, 9‐0 Prolene, D‐8229, CTC‐6L sutures in two eyes, and 10‐0 Prolene, 9090, CTC‐6 suture in one eye, the tears were sutured. A tear in the CCC was created again in the same way as the first tear. The distance between the calliper's arms needed to tear the CCC was documented again. Results Suturing of the tear restored some of the strength/elasticity of the CCC. Better results were found while using the 9‐0 Prolene, D‐8229, CTC‐6L sutures than with the two others sutures. Conclusions Suturing of a broken CCC can restore at least some of the strength/elasticity of the CCC. This can be important before intraocular lens (IOL) implantation for the safety of the implantation or after the implantation to ensure proper fixation of the IOL. PMID:16547318

  10. Social Cognition and the Anterior Temporal Lobes

    PubMed Central

    Ross, Lars A.; Olson, Ingrid R.

    2009-01-01

    Two distinct literatures have emerged on the functionality of the anterior temporal lobes (ATL): in one field, the ATLs are conceived of as a repository for semantic or conceptual knowledge. In another field, the ATLs are thought to play some undetermined role in social-emotional functions such as Theory of Mind. Here we attempted to reconcile these distinct functions by assessing whether social semantic processing can explain ATL activation in other social cognitive tasks. Social semantic functions refer to knowledge about social concepts and rules. In a first experiment we tested the idea that social semantic representations can account for activations in the ATL to social attribution stimuli such as Heider and Simmel animations. Left ATL activations to Heider and Simmel stimuli overlapped with activations to social words. In a second experiment we assessed the putative roles of the ATLs in the processing of narratives and theory of mind content and found evidence for a role of the ATLs in the processing of theory of mind but not narrative per se. These findings indicate that the ATLs are part of a neuronal network supporting social cognition and that they are engaged when tasks demand access to social conceptual knowledge. PMID:19931397

  11. Midline Anterior Craniofacial Approach for Malignancy

    PubMed Central

    Wellman, Bryan John; Traynelis, Vincent C.; McCulloch, Timothy M.; Funk, Gerry F.; Menezes, Arnold H.; Hoffman, Henry T.

    1999-01-01

    Thirty consecutive cases of midline anterior craniofacial procedures for the treatment of malignant neoplasms arising from the paranasal sinuses were reviewed. Posterior and lateral base craniofacial procedures were specifically excluded. This review compares the results, in terms of survival and major complication rate, between en bloc and piecemeal resections. The average follow-up was 4 years and 3 months. Sixteen patients were treated with an en bloc resection. The major complication rate was 31%. One-year survival rate was 94% for the en bloc resection group, 67% for patients with positive margins, and 100% for patients with clear margins. Three-year survival for en bloc resection dropped to 56, 33, and 67%, respectively. Fourteen patients were treated with piecemeal resections. The major complication rate was 21%. One-year survival rate was 83% for the piecemeal resection group, 60% for patients with positive margins, and 100% for patients with clear margins. Three-year survival dropped to 70, 60, and 80%, respectively. Although it is considered desirable to obtain an en bloc resection in some craniofacial procedures, we conclude that a piecemeal resection is a viable alternative in situations where an en bloc procedure is difficult to obtain safely. ImagesFigure 1p43-bFigure 2p44-b PMID:17171080

  12. Guideline on anterior cruciate ligament injury

    PubMed Central

    2012-01-01

    The Dutch Orthopaedic Association has a long tradition of development of practical clinical guidelines. Here we present the recommendations from the multidisciplinary clinical guideline working group for anterior cruciate ligament injury. The following 8 clinical questions were formulated by a steering group of the Dutch Orthopaedic Association. What is the role of physical examination and additional diagnostic tools? Which patient-related outcome measures should be used? What are the relevant parameters that influence the indication for an ACL reconstruction? Which findings or complaints are predictive of a bad result of an ACL injury treatment? What is the optimal timing for surgery for an ACL injury? What is the outcome of different conservative treatment modalities? Which kind of graft gives the best result in an ACL reconstruction? What is the optimal postoperative treatment concerning rehabilitation, resumption of sports, and physiotherapy? These 8 questions were answered and recommendations were made, using the “Appraisal of Guidelines for Research and Evaluation” instrument. This instrument seeks to improve the quality and effectiveness of clinical practical guidelines by establishing a shared framework to develop, report, and assess. The steering group has also developed 7 internal indicators to aid in measuring and enhancing the quality of the treatment of patients with an ACL injury, for use in a hospital or practice. PMID:22900914

  13. Guideline on anterior cruciate ligament injury.

    PubMed

    Meuffels, Duncan E; Poldervaart, Michelle T; Diercks, Ron L; Fievez, Alex W F M; Patt, Thomas W; Hart, Cor P van der; Hammacher, Eric R; Meer, Fred van der; Goedhart, Edwin A; Lenssen, Anton F; Muller-Ploeger, Sabrina B; Pols, Margreet A; Saris, Daniel B F

    2012-08-01

    The Dutch Orthopaedic Association has a long tradition of development of practical clinical guidelines. Here we present the recommendations from the multidisciplinary clinical guideline working group for anterior cruciate ligament injury. The following 8 clinical questions were formulated by a steering group of the Dutch Orthopaedic Association. What is the role of physical examination and additional diagnostic tools? Which patient-related outcome measures should be used? What are the relevant parameters that influence the indication for an ACL reconstruction? Which findings or complaints are predictive of a bad result of an ACL injury treatment? What is the optimal timing for surgery for an ACL injury? What is the outcome of different conservative treatment modalities? Which kind of graft gives the best result in an ACL reconstruction? What is the optimal postoperative treatment concerning rehabilitation, resumption of sports, and physiotherapy? These 8 questions were answered and recommendations were made, using the "Appraisal of Guidelines for Research and Evaluation" instrument. This instrument seeks to improve the quality and effectiveness of clinical practical guidelines by establishing a shared framework to develop, report, and assess. The steering group has also developed 7 internal indicators to aid in measuring and enhancing the quality of the treatment of patients with an ACL injury, for use in a hospital or practice. PMID:22900914

  14. Anterior mediastinotomy--a diagnostic tool.

    PubMed

    Adegboye, V O; Obajimi, M O; Ogunsehinde, O O; Brimmo, I A; Adebo, O A

    2001-12-01

    This is a review of our experience with anterior mediastinotomy (AM) in the diagnosis and evaluation of diseases of the mediastinum and lung. Thirty consecutive patients who had AM between 1984 and 1999 were retrospectively studied. The mean age of patients was 28 +/- 6.5 years. There were 22 males to 8 females. Sixteen patients had superior vena cava (SVC) obstruction (12 patients with lung cancer, 4 with primary mediastinal tumours), 4 patients had radiological evidence of mediastinal contiguity of upper lobe tumours and 10 patients had primary mediastinal tumours. AM was 1st procedure in 10 patients and 2nd procedure in 20 patients after failed or inconclusive result from FNAB, scalene node/cervical lymph node biopsy or bronchoscopy. Eighteen right-sided and 12 left-sided AMs were performed. Satisfactory histological diagnoses were achieved in all patients. Complications were easily controlled bleeding (4 patients) and life-threatening haemorrhage in 2 patients. Three patients had delayed wound healing and 4 had inadvertent pleural entries. There was no mortality temporarily related to the procedure. We conclude that AM is valuable as a surgical technique for obtaining tissue for histological purposes in diseases of the mediastinum and the lung when tissue specimens from less invasive procedures are unsatisfactory. PMID:14510116

  15. Normalizing videos of anterior eye segment surgeries.

    PubMed

    Quellec, Gwénolé; Charriére, Katia; Lamard, Mathieu; Cochener, Béatrice; Cazuguel, Guy

    2014-01-01

    Anterior eye segment surgeries are usually video-recorded. If we are able to efficiently analyze surgical videos in real-time, new decision support tools will emerge. The main anatomical landmarks in these videos are the pupil boundaries and the limbus, but segmenting them is challenging due to the variety of colors and textures in the pupil, the iris, the sclera and the lids. In this paper, we present a solution to reliably normalize the center and the scale in videos, without explicitly segmenting these landmarks. First, a robust solution to track the pupil center is presented: it uses the fact that the pupil boundaries, the limbus and the sclera / lid interface are concentric. Second, a solution to estimate the zoom level is presented: it relies on the illumination pattern reflected on the cornea. The proposed solution was assessed in a dataset of 186 real-live cataract surgery videos. The distance between the true and estimated pupil centers was equal to 8.0 ± 6.9% of the limbus radius. The correlation between the estimated zoom level and the true limbus size in images was high: R = 0.834. PMID:25569912

  16. Knee Bracing After Anterior Cruciate Ligament Reconstruction.

    PubMed

    Rodríguez-Merchán, E Carlos

    2016-07-01

    Although some articles in the literature are in favor of the use of a postoperative brace after anterior cruciate ligament (ACL) reconstruction, this review found that several systematic reviews and other reports on the topic do not support the use of a postoperative brace after ACL reconstruction. There is no scientific evidence so far to support the routine use of a functional knee brace following a successful ACL reconstruction in the postoperative course. Most authors believe that bracing is not necessary. There is insufficient evidence to inform current practice. Good-quality randomized trials are required to remedy this situation. Future studies should better define the role of a brace following ACL surgery. A search of MEDLINE for articles published between January 1, 1995, and September 30, 2013, was performed. Key search terms used were ACL reconstruction and knee brace. Ninety-one articles were found, but only 28 focused on the subject of bracing after ACL reconstruction and were selected for this review. Several systematic reviews and randomized, controlled trials on the topic do not recommend the use of postoperative brace after ACL reconstruction. Postoperative bracing after ACL reconstruction does not seem to help with pain, function, rehabilitation, and stability. The literature does not support the use of a postoperative brace following ACL reconstruction. [Orthopedics. 2016; 39(4):e602-e609.]. PMID:27203412

  17. MRI of anterior cruciate ligament healing

    SciTech Connect

    Ihara, Hidetoshi; Miwa, Megumi; Deya, Keizo; Torisu, Kenji

    1996-03-01

    The purpose of this study was to evaluate using MRI the natural healing of the anterior cruciate ligament (ACL) when treated conservatively by early protective motion. Consecutive acute complete intraligamentous ruptures of the ACL in 50 cases that were allowed to heal without surgery were evaluated before and after 3 month treatment by MRI, arthroscopy, and stress radiographs. Twenty-nine of the 50 patients were also reevaluated 11 months from the initial injury, of which 7 were reevaluated again 24 months from the initial injury by MRI. The MR appearance of the treated ACL was categorized into four grades depending on homogeneity, straight band, and size. MR assessment of the ACL after 3 month treatment demonstrated a well defined normal-sized straight band in 37 cases (74%). There was a significant relationship between the 3 and 11 month MR evaluations (r. = 0.801, p < 0.0001). There were also significant relationships between the MR and arthroscopic evaluations (r, = 0.455, p < 0.005) and between the MR and stress radiographic evaluations (r, = 0.348, p < 0.025) after the 3 month treatment. MRI can demonstrate ACL healing when treated conservatively with early protective mobilization. 40 refs., 3 figs., 2 tabs.

  18. Shear Instabilities in Granular Flows

    NASA Astrophysics Data System (ADS)

    Shinbrot, Troy

    2003-03-01

    Unstable waves have long been studied in fluid shear layers. These waves affect transport in the atmosphere and oceans as well as slipstream stability behind ships, planes, and heat transfer devices. Corresponding instabilities in granular flows have not previously been documented, despite the importance of these flows in geophysical and industrial systems. We report here that breaking waves can form at the interface between two streams of identical grains downstream of a splitter plate. These waves appear abruptly in flow down an inclined plane as either shear rate or angle of incline is changed, and we analyze a granular flow model that qualitatively agrees with our experimental data. The waves appear from the model to be a manifestation of a competition between shear and extensional strains in the flowing granular bed, and we propose a dimensionless group to govern the transition between steady and wavy flows.

  19. Shear instabilities in granular flows

    NASA Astrophysics Data System (ADS)

    Goldfarb, David J.; Glasser, Benjamin J.; Shinbrot, Troy

    2002-01-01

    Unstable waves have been long studied in fluid shear layers. These waves affect transport in the atmosphere and oceans, in addition to slipstream stability behind ships, aeroplanes and heat-transfer devices. Corresponding instabilities in granular flows have not been previously documented, despite the importance of these flows in geophysical and industrial systems. Here we report that breaking waves can form at the interface between two streams of identical grains flowing on an inclined plane downstream of a splitter plate. Changes in either the shear rate or the angle of incline cause such waves to appear abruptly. We analyse a granular flow model that agrees qualitatively with our experimental data; the model suggests that the waves result from competition between shear and extensional strains in the flowing granular bed. We propose a dimensionless shear number that governs the transition between steady and wavy flows.

  20. Shear instabilities in granular flows.

    PubMed

    Goldfarb, David J; Glasser, Benjamin J; Shinbrot, Troy

    2002-01-17

    Unstable waves have been long studied in fluid shear layers. These waves affect transport in the atmosphere and oceans, in addition to slipstream stability behind ships, aeroplanes and heat-transfer devices. Corresponding instabilities in granular flows have not been previously documented, despite the importance of these flows in geophysical and industrial systems. Here we report that breaking waves can form at the interface between two streams of identical grains flowing on an inclined plane downstream of a splitter plate. Changes in either the shear rate or the angle of incline cause such waves to appear abruptly. We analyse a granular flow model that agrees qualitatively with our experimental data; the model suggests that the waves result from competition between shear and extensional strains in the flowing granular bed. We propose a dimensionless shear number that governs the transition between steady and wavy flows. PMID:11797003

  1. Evolution of genetic instability in heterogeneous tumors.

    PubMed

    Asatryan, Ani D; Komarova, Natalia L

    2016-05-01

    Genetic instability is an important characteristic of cancer. While most cancers develop genetic instability at some stage of their progression, sometimes a temporary rise of instability is followed by the return to a relatively stable genome. Neither the reasons for these dynamics, nor, more generally, the role of instability in tumor progression, are well understood. In this paper we develop a class of mathematical models to study the evolutionary competition dynamics among different sub-populations in a heterogeneous tumor. We observe that despite the complexity of this multi-component and multi-process system, there is only a small number of scenarios expected in the context of the evolution of instability. If the penalty incurred by unstable cells (the decrease in the growth due to deleterious mutations) is high compared with the gain (the production rate of advantageous mutations), then instability does not evolve. In the opposite case, instability evolves and comes to dominate the system. In the intermediate parameter regime, instability is generated but later gives way to stable clones. Moreover, the model also informs us of the patterns of instability for cancer lineages corresponding to different stages of progression. It is predicted that mutations causing instability are merely "passengers" in tumors that have undergone only a small number of malignant mutations. Further down the path of carcinogenesis, however, unstable cells are more likely to give rise to the winning clonal wave that takes over the tumor and carries the evolution forward, thus conferring a causal role of the instability in such cases. Further, each individual clonal wave (i.e. cells harboring a fixed number of malignant driver mutations) experiences its own evolutionary history. It can fall under one of three types of temporal behavior: stable throughout, unstable to stable, or unstable throughout. Which scenario is realized depends on the subtle (but predictable) interplay among

  2. Visco-resistive plasmoid instability

    NASA Astrophysics Data System (ADS)

    Comisso, Luca; Grasso, Daniela

    2016-03-01

    The plasmoid instability in visco-resistive current sheets is analyzed in both the linear and nonlinear regimes. The linear growth rate and the wavenumber are found to scale as S1 /4(1+Pm ) -5 /8 and S3 /8(1+Pm ) -3 /16 with respect to the Lundquist number S and the magnetic Prandtl number Pm. Furthermore, the linear layer width is shown to scale as S-1 /8(1+Pm ) 1 /16 . The growth of the plasmoids slows down from an exponential growth to an algebraic growth when they enter into the nonlinear regime. In particular, the time-scale of the nonlinear growth of the plasmoids is found to be τNL˜S-3 /16(1+Pm) 19 /32τA,L . The nonlinear growth of the plasmoids is radically different from the linear one, and it is shown to be essential to understand the global current sheet disruption. It is also discussed how the plasmoid instability enables fast magnetic reconnection in visco-resistive plasmas. In particular, it is shown that the recursive plasmoid formation can trigger a collisionless reconnection regime if S ≳Lc s(ɛclk) -1(1+Pm) 1 /2 , where Lcs is the half-length of the global current sheet and lk is the relevant kinetic length scale. On the other hand, if the current sheet remains in the collisional regime, the global (time-averaged) reconnection rate is shown to be ≈ɛcvA ,uBu(1+Pm) -1 /2 , where ɛc is the critical inverse aspect ratio of the current sheet, while vA,u and Bu are the Alfvén speed and the magnetic field upstream of the global reconnection layer.

  3. Anterior dental microwear texture analysis of the Krapina Neandertals

    NASA Astrophysics Data System (ADS)

    Krueger, Kristin L.; Ungar, Peter S.

    2012-12-01

    Some Neandertal anterior teeth show unusual and excessive gross wear, commonly explained by non-dietary anterior tooth use, or using the anterior dentition as a tool, clamp, or third hand. This alternate use is inferred from aboriginal arctic populations, who used their front teeth in this manner. Here we examine anterior dental microwear textures of the Krapina Neandertals to test this hypothesis and further analyze tooth use in these hominins. Microwear textures from 17 Krapina Dental People were collected by white-light confocal profilometry using a 100x objective lens. Four adjacent scans were generated, totaling an area of 204x276 μm, and were analyzed using Toothfrax and SFrax SSFA software packages. The Neandertals were compared to six bioarchaeological/ethnographic samples with reported variation in diet, abrasive load, and non-dietary anterior tooth use. Results indicate that Krapina anterior teeth lack extreme microwear textures expected of hominins exposed to heavy abrasives or those that regularly generated high stresses associated with intense use of the front teeth as tools. Krapina hominins have microwear attributes in common with Coast Tsimshian, Aleut, and Puye Pueblo samples. Collectively, this suggests that the Krapina Neandertals faced moderate abrasive loads and only periodically used their anterior teeth as tools for non-diet related behaviors.

  4. Thermal instability during an electrical wire explosion

    NASA Astrophysics Data System (ADS)

    Oreshkin, V. I.

    2008-09-01

    The development of thermal instabilities during an electrical wire explosion is analyzed in the present work based on the methods of small perturbation theory. For two cases, with and without allowance for motion, the dispersion equations are derived that describe a relationship between the instantaneous buildup increment and the axial wave vector component. It is demonstrated that the thermal instabilities are always formed during electrical explosion, irrespective of the explosion mode. There are three destabilizing factors leading to the development of the thermal instabilities: a temperature rise, an increase in the specific resistance with increasing temperature, and an increase in the specific resistance with decreasing density. The critical value of current density below which the sausage instabilities grow faster than the thermal ones and above which, on the contrary, the thermal instabilities are dominant can be found for each metal.

  5. Tidal instability in exoplanetary systems evolution

    NASA Astrophysics Data System (ADS)

    Cébron, D.; Moutou, C.; Le Bars, M.; Le Gal, P.; Farès, R.

    2011-02-01

    A new element is proposed to play a role in the evolution of extrasolar planetary systems: the tidal (or elliptical) instability. It comes from a parametric resonance and takes place in any rotating fluid whose streamlines are (even slightly) elliptically deformed. Based on theoretical, experimental and numerical works, we estimate the growth rate of the instability for hot-jupiter systems, when the rotation period of the star is known. We present the physical process, its application to stars, and preliminary results obtained on a few dozen systems, summarized in the form of a stability diagram. Most of the systems are trapped in the so-called "forbidden zone", where the instability cannot grow. In some systems, the tidal instability is able to grow, at short timescales compared to the system evolution. Implications are discussed in the framework of misaligned transiting systems, as the rotational axis of the star would be unstable in systems where this elliptical instability grows.

  6. Submesoscale baroclinic instability and the Balance Equations

    NASA Astrophysics Data System (ADS)

    Grooms, Ian

    2015-11-01

    Ocean submesoscale baroclinic instability is studied in the framework of the Balance Equations. The Balance Equations are an intermediate model that includes balanced ageostrophic effects with higher accuracy than the quasigeostrophic approximation, but rules out unbalanced wave motions; as such, they are particularly suited to the study of baroclinic instability in submesoscale ocean dynamics. The linear baroclinic instability problem is developed in generality and then specialized to the case of constant vertical shear. The primary finding is that at low Richardson numbers the growth rate of some instability modes is increased compared to larger-scale quasigeostrophic dynamics, and that the increase can be attributed to both ageostrophic baroclinic production and shear production of perturbation energy. This suggests that the nonlinear development of submesoscale baroclinic instability will proceed more vigorously than mesoscale/quasigeostrophic, and may include a downscale/forward transfer of kinetic energy.

  7. Parametric instabilities in the LCGT arm cavity

    NASA Astrophysics Data System (ADS)

    Yamamoto, K.; Uchiyama, T.; Miyoki, S.; Ohashi, M.; Kuroda, K.; Numata, K.

    2008-07-01

    We evaluated the parametric instabilities of LCGT (Japanese interferometric gravitational wave detector project) arm cavity. The number of unstable modes of LCGT is 10-times smaller than that of Advanced LIGO (USA). Since the strength of the instabilities of LCGT depends on the mirror curvature more weakly than that of Advanced LIGO, the requirement of the mirror curvature accuracy is easier to be achieved. The difference in the parametric instabilities between LCGT and Advanced LIGO is because of the thermal noise reduction methods (LCGT, cooling sapphire mirrors; Advanced LIGO, fused silica mirrors with larger laser beams), which are the main strategies of the projects. Elastic Q reduction by the barrel surface (0.2 mm thickness Ta2O5) coating is effective to suppress instabilities in the LCGT arm cavity. Therefore, the cryogenic interferometer is a smart solution for the parametric instabilities in addition to thermal noise and thermal lensing.

  8. Multidirectional Instability Accompanying an Inferior Labral Cyst

    PubMed Central

    Ji, Jong-Hun; Kim, Sung-Jae

    2010-01-01

    Paralabral cyst of the shoulder joint can be observed in 2% to 4% of the general population, particularly in men during the third and fourth decade. On average, these cysts measure 10 mm to 20 mm in diameter and are located preferentially on the postero-superior aspect of the glenoid. The MRI has increased the frequency of the diagnosis of paralabral cysts of the shoulder joint. Paralabral cysts of the shoulder joint usually develop in the proximity of the labrum. The relationship between shoulder instability and labral tears is well known, however, the association of shoulder instability with a paralabral cyst is rare. Shoulder instability may cause labral injury or labral injury may cause shoulder instability, and then injured tear develops paralabral cyst. In our patient, the inferior paralabral cyst may be associated with inferior labral tears and instability MRI. PMID:20514270

  9. Control of interfacial instabilities using flow geometry

    NASA Astrophysics Data System (ADS)

    Al-Housseiny, Talal T.; Tsai, Peichun A.; Stone, Howard A.

    2012-10-01

    The displacement of one fluid by another is one of the most common processes involving interfacial instabilities. It is universally accepted that, in a uniform medium, flow displacement is unstable when a low-viscosity fluid invades a fluid of higher viscosity: the classical viscous fingering instability. Consequently, once fluid properties are specified, opportunities for control become very limited. However, real systems where displacement instabilities occur, such as porous structures, lung airways and printing devices, are rarely uniform. We find that the simplest heterogeneity--a gradient in the flow passage--can lead to fundamentally different displacement behaviours. We use this finding to either inhibit or trigger an instability and, hence, to devise a strategy to manipulate instabilities in fluid-fluid systems. The control setting we identify has a wide spectrum of applications ranging from small-scale technologies such as microfluidics to large-scale operations such as enhanced oil recovery.

  10. Taming contact line instability for pattern formation.

    PubMed

    Deblais, A; Harich, R; Colin, A; Kellay, H

    2016-01-01

    Coating surfaces with different fluids is prone to instability producing inhomogeneous films and patterns. The contact line between the coating fluid and the surface to be coated is host to different instabilities, limiting the use of a variety of coating techniques. Here we take advantage of the instability of a receding contact line towards cusp and droplet formation to produce linear patterns of variable spacings. We stabilize the instability of the cusps towards droplet formation by using polymer solutions that inhibit this secondary instability and give rise to long slender cylindrical filaments. We vary the speed of deposition to change the spacing between these filaments. The combination of the two gives rise to linear patterns into which different colloidal particles can be embedded, long DNA molecules can be stretched and particles filtered by size. The technique is therefore suitable to prepare anisotropic structures with variable properties. PMID:27506626

  11. Tensile Instability in a Thick Elastic Body.

    PubMed

    Overvelde, Johannes T B; Dykstra, David M J; de Rooij, Rijk; Weaver, James; Bertoldi, Katia

    2016-08-26

    A range of instabilities can occur in soft bodies that undergo large deformation. While most of them arise under compressive forces, it has previously been shown analytically that a tensile instability can occur in an elastic block subjected to equitriaxial tension. Guided by this result, we conducted centimeter-scale experiments on thick elastomeric samples under generalized plane strain conditions and observed for the first time this elastic tensile instability. We found that equibiaxial stretching leads to the formation of a wavy pattern, as regions of the sample alternatively flatten and extend in the out-of-plane direction. Our work uncovers a new type of instability that can be triggered in elastic bodies, enlarging the design space for smart structures that harness instabilities to enhance their functionality. PMID:27610857

  12. Taming contact line instability for pattern formation

    PubMed Central

    Deblais, A.; Harich, R.; Colin, A.; Kellay, H.

    2016-01-01

    Coating surfaces with different fluids is prone to instability producing inhomogeneous films and patterns. The contact line between the coating fluid and the surface to be coated is host to different instabilities, limiting the use of a variety of coating techniques. Here we take advantage of the instability of a receding contact line towards cusp and droplet formation to produce linear patterns of variable spacings. We stabilize the instability of the cusps towards droplet formation by using polymer solutions that inhibit this secondary instability and give rise to long slender cylindrical filaments. We vary the speed of deposition to change the spacing between these filaments. The combination of the two gives rise to linear patterns into which different colloidal particles can be embedded, long DNA molecules can be stretched and particles filtered by size. The technique is therefore suitable to prepare anisotropic structures with variable properties. PMID:27506626

  13. Rayleigh-Taylor instability in elastic solids.

    PubMed

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

    2005-11-01

    We present an analytical model for the Rayleigh-Taylor instability that allows for an approximate but still very accurate and appealing description of the instability physics in the linear regime. The model is based on the second law of Newton and it has been developed with the aim of dealing with the instability of accelerated elastic solids. It yields the asymptotic instability growth rate but also describes the initial transient phase determined by the initial conditions. We have applied the model to solid/solid and solid/fluid interfaces with arbitrary Atwood numbers. The results are in excellent agreement with previous models that yield exact solutions but which are of more limited validity. Our model allows for including more complex physics. In particular, the present approach is expected to lead to a more general theory of the instability that would allow for describing the transition to the plastic regime. PMID:16383751

  14. Magnetothermal instability with generalized Ohm's law

    SciTech Connect

    Bora, M.P.; Talwar, S.P. )

    1993-03-01

    The problem of thermal instability, having bearing on the formation of astrophysical condensations, is investigated for a hydromagnetic fluid obeying generalized Ohm's law, both for self-gravitating and nongravitating configurations. Effects of finite Larmor frequency, resistivity, and finite plasma frequency on the stability of the system are studied and the condition of instabilities are derived for a temperature-dependent and density-dependent heat-loss function. It is found that the condition of instability for propagation parallel to the ambient magnetic field is independent of finite resistivity, Hall current, and electron inertia effects and also of the magnetic field strength. For transverse propagation, however, the instability criterion involves the field strength, resistivity, and electron inertia terms. The Hall current is found to modify the growth rates for generally inclined propagation only. Both monotonically unstable and overstable modes of instability arise in the system depending on the dependence of the heat-loss function on the local density and temperature.

  15. The electromagnetic ion cyclotron beam anisotropy instability

    NASA Technical Reports Server (NTRS)

    Peter Gary, S.; Schriver, David

    1987-01-01

    Electromagnetic instabilities driven by an anisotropic, relatively cool ion beam are studied for the case in which both the beam and the instabilities propagate parallel or antiparallel to a uniform magnetic field. At modest beam-core relative drift speeds, sufficiently large perpendicular-to-parallel beam temperature ratios and sufficiently large plasma beta, the mode of fastest growth rate is the ion cyclotron beam anisotropy instability. Because the right-hand polarized waves observed upstream of slow shocks in the earth's magnetotail can lead to the appropriate beam anisotropy, the ion cyclotron instability may be present and account for the left-hand polarized magnetic waves observed there. Also, because of its relatively low phase speed, the ion cyclotron beam anisotropy instability may provide the scattering necessary for ion Fermi acceleration at slow shocks of sufficiently high plasma beta.

  16. Analysis of nuclear reactor instability phenomena

    SciTech Connect

    Lahey, R.T. Jr.

    1993-01-01

    The phenomena known as density-wave instability often occurs in phase change systems, such as boiling water nuclear reactors (BWRS). Our current understanding of density-wave oscillations is in fairly good shape for linear phenomena (eg, the onset of instabilities) but is not very advanced for non-linear phenomena [Lahey and Podowski, 1989]. In particular, limit cycle and chaotic instability modes are not well understood in boiling systems such as current and advanced generation BWRs (eg, SBWR). In particular, the SBWR relies on natural circulation and is thus inherently prone to problems with density-wave instabilities. The purpose of this research is to develop a quantitative understanding of nonlinear nuclear-coupled density-wave instability phenomena in BWRS. This research builds on the work of Achard et al [1985] and Clausse et al [1991] who showed, respectively, that Hopf bifurcations and chaotic oscillations may occur in boiling systems.

  17. Taming contact line instability for pattern formation

    NASA Astrophysics Data System (ADS)

    Deblais, A.; Harich, R.; Colin, A.; Kellay, H.

    2016-08-01

    Coating surfaces with different fluids is prone to instability producing inhomogeneous films and patterns. The contact line between the coating fluid and the surface to be coated is host to different instabilities, limiting the use of a variety of coating techniques. Here we take advantage of the instability of a receding contact line towards cusp and droplet formation to produce linear patterns of variable spacings. We stabilize the instability of the cusps towards droplet formation by using polymer solutions that inhibit this secondary instability and give rise to long slender cylindrical filaments. We vary the speed of deposition to change the spacing between these filaments. The combination of the two gives rise to linear patterns into which different colloidal particles can be embedded, long DNA molecules can be stretched and particles filtered by size. The technique is therefore suitable to prepare anisotropic structures with variable properties.

  18. Taylor instability in rhyolite lava flows

    NASA Technical Reports Server (NTRS)

    Baum, B. A.; Krantz, W. B.; Fink, J. H.; Dickinson, R. E.

    1989-01-01

    A refined Taylor instability model is developed to describe the surface morphology of rhyolite lava flows. The effect of the downslope flow of the lava on the structures resulting from the Taylor instability mechanism is considered. Squire's (1933) transformation is developed for this flow in order to extend the results to three-dimensional modes. This permits assessing why ridges thought to arise from the Taylor instability mechanism are preferentially oriented transverse to the direction of lava flow. Measured diapir and ridge spacings for the Little and Big Glass Mountain rhyolite flows in northern California are used in conjunction with the model in order to explore the implications of the Taylor instability for flow emplacement. The model suggests additional lava flow features that can be measured in order to test whether the Taylor instability mechanism has influenced the flows surface morphology.

  19. Anterior segment parameters and eyelids in systemic sclerosis.

    PubMed

    Sahin Atik, Sevinc; Koc, Feray; Akin Sari, Sirin; Sefi Yurdakul, Nazife; Ozmen, Mustafa; Akar, Servet

    2016-08-01

    To evaluate main numerical parameters of anterior segment and the effects of eyelid skin changes on these parameters in patients with systemic sclerosis (SSc). Thirty-four patients with SSc and 34 healthy individuals were enrolled. Besides full eye examination, anterior segment measurements including anterior chamber depth (ACD), anterior chamber volume, anterior chamber angle width, central corneal thickness, pupil size, corneal volume and keratometry were obtained using a Sirius Scheimpflug/Placido photography-based topography system. Eyelid thickness was evaluated using the scala of the modified Rodnan skin score and the patients were subgrouped with respect to these scores to evaluate the effect of eyelid thickening on the anterior segment parameters. Age and sex distributions of the groups were similar (p > 0.05). SSc patients had steeper and thinner corneas, smaller corneal volumes, narrower, shallower and smaller anterior segments but only the mean ACD value of right eyes was found significantly less than those of the controls (p = 0.047). The mean ACD values of SSc subgroup patients with moderate to severe eyelid thickening (50 %) had lower ACD measurements compared to those of control group. (p = 0.043 for the right eyes, p = 0.070 for the left eyes). However, SSc subgroup patients with none to mild eyelid thickening (50 %) had similar anterior segment parameters with control subjects (p > 0.05). Anterior chamber parameters of the SSc patients could show significant differences. These differences occur parallel to the eyelid changes but not secondary to it. PMID:26694912

  20. Rotordynamic Instability Problems in High-Performance Turbomachinery

    NASA Technical Reports Server (NTRS)

    1982-01-01

    Rotor dynamic instability problems in high performance turbomachinery are reviewed. Mechanical instability mechanisms are discussed. Seal forces and working fluid forces in turbomachinery are discussed. Control of rotor instability is also investigated.

  1. Bilateral anterior choroidal artery infarction presenting with progressive somnolence.

    PubMed

    van Son, Brechtje; Vandevenne, Jan; Viaene, Pieter

    2014-09-01

    A 55-year-old woman was admitted with a 3 days history of increasing lethargy with bradyphrenia and apathy. She progressively developed severe somnolence with marked abulia, right hemiparesis, right hemianopsia, and pseudobulbar palsy. Brain magnetic resonance imaging showed the rare image of bilateral acute anterior choroidal artery infarction. Pseudobulbar mutism and in rare cases abulia have been described in acute anterior choroidal artery infarction contralateral to an older lesion in mirror position. Although neurologic deterioration is not infrequent in anterior choroidal artery territory infarcts, the absence of focal neurologic signs on admission is rare and did not raise suspicion of acute stroke. PMID:25106836

  2. Fibrinous anterior uveitis following laser in situ keratomileusis.

    PubMed

    Parmar, Pragya; Salman, Amjad; Rajmohan, M; Jesudasan, Nelson C A

    2009-01-01

    A 29-year-old woman who underwent laser in situ keratomileusis (LASIK) for myopic astigmatism in both eyes presented with severe pain, photophobia and decreased visual acuity in the left eye eight days after surgery. Examination revealed severe anterior uveitis with fibrinous exudates in the anterior chamber, flap edema and epithelial bullae. Laboratory investigations for uveitis were negative and the patient required systemic and intensive topical steroids with cycloplegics to control the inflammation. This case demonstrates that severe anterior uveitis may develop after LASIK and needs prompt and vigorous management for resolution. PMID:19574707

  3. Involuntary inferior and multidirectional instability of the shoulder: etiology, recognition, and treatment.

    PubMed

    Neer, C S

    1985-01-01

    Multidirectional and inferior instability of the shoulder is not rare. Etiological factors include various combinations of (a) repetitive injuries, (b) inherent joint laxity, and (c) one or more major injuries. It is seen in athletic and active patients without generalized joint laxity and as well in sedentary patients with hypermobile joints. Standard operations for unidirectional anterior or posterior dislocations fail to correct multidirectional instability because they do not correct inferior instability and they may displace the head in fixed subluxation to the opposite side leading to severe arthritis ("arthritis of dislocations"). Proper detection depends on suspecting its possibility in all types of patients and in a wide age range as well. Helpful signs include the sulcus sign, positive apprehension test in multiple directions, stress roentgenograms and fluoroscopy, and evaluations under anesthesia. Arthroscopy may be helpful in doubtful cases, but the findings require clinical interpretation. Selection of patients with multidirectional instability for surgery is extremely difficult because it requires not only great care in determining all directions of instability and planning the repair but also determining the motivation of the patient and excluding the possibility of some other condition being present that is causing pain rather than the joint laxity. The results of inferior capsular shift have continued to withstand the test of time and, though it is more difficult than standard procedures, is considered a very helpful procedure in the treatment of these difficult lesions. The principle is to reduce capsular laxity on all three sides by shortening and reinforcing and to reduce the joint volume.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:3833944

  4. New Radiographic Index for Occipito-Cervical Instability

    PubMed Central

    Moon, Seong-Hwan; Kim, Tae-Hwan; Oh, Jae Keun; Nam, Ji Hoon; Jung, Jae Kyun; Riew, K. Daniel

    2016-01-01

    Study Design Retrospective study. Purpose To propose a new radiographic index for occipito-cervical instability. Overview of Literature Symptomatic atlanto-occipital instability requires the fusion of the atlanto-occipital joint. However, measurements of occipito-cervical translation using the Wiesel-Rothman technique, Power's ratio, and basion-axial interval are unreliable because the radiologic landmarks in the occipito-cervical junction lack clarity in radiography. Methods One hundred four asymptomatic subjects were evaluated with lateral cervical radiographs in neutral, flexion and extension. They were stratified by age and included 52 young (20–29 years) and 52 middle-aged adults (50–59 years). The four radiographic reference points were posterior edge of hard palate (hard palate), posteroinferior corner of the most posterior upper molar tooth (molar), posteroinferior corner of the C1 anterior ring (posterior C1), and posteroinferior corner of the C2 vertebral body (posterior C2). The distance from posterior C1 and posterior C2 to the above anatomical landmarks was measured to calculate the range of motion (ROM) on dynamic radiographs. To determine the difference between the two age groups, unpaired t-tests were used. The statistical significance level was set at p<0.05. Results The ROM was 4.8±7.3 mm between the hard palate and the posterior C1, 9.9±10.2 mm between the hard palate and the posterior C2, 1.7±7.2 mm between the molar to the posterior C1, and 10.4±12.1 mm between the molar to the posterior C2. There was no statistically significant difference for the ROM between the young- and the middle-aged groups. The intra-observer reliability for new radiographic index was good. The inter-observer reliability for the ROM measured by the hard palate was low, but was better than that by the molar. Conclusions ROM measured by the hard palate might be a useful new radiographic index in cases of occipito-cervical instability. PMID:26949467

  5. Anterior Cruciate Ligament Reconstruction and Osteoarthritis

    PubMed Central

    Duthon, Victoria; Servien, Elvire; Neyret, Philippe

    2013-01-01

    Objective: The goals of this study are to address several questions, the answers to which are key to the understanding and eventually to the prevention of this frequent source of morbidity. These questions include the following: (1) What is the natural history of anterior cruciate ligament (ACL) deficiency? (2) How important is the status of the meniscus at the time of reconstruction? (3) Does ACL reconstruction prevent the development of osteoarthritis in the long term? (4) Can we predict which patients will develop osteoarthritis? (5) What can be done? Design: This study addresses the key questions above through the long-term follow-up of a cohort of patients treated with ACL reconstruction by Professor Henri Dejour in Lyon, France, supplemented with a review of the relevant literature. Results: The prevalence of osteoarthritis in ACL-deficient knees is about 40% after 15 years and close to 90% after 25 to 35 years. It remains unclear whether reconstruction of the ACL significantly reduces this risk. The status of the meniscus at the time of ACL reconstruction is a strong predictor of the risk of osteoarthritis: Patients who undergo total meniscectomy are at 2- to 10-fold increased risk of developing osteoarthritis relative to those with intact menisci. Patients showing early evidence of arthritis at short- to medium-term follow-up are at high risk for progression over subsequent years. Numerous emerging techniques may provide tools to more effectively prevent and treat osteoarthritis following ACL injury in the future. Conclusion: Osteoarthritis following ACL injury continues to be a major problem requiring further research. PMID:26069662

  6. Anterior Cruciate Ligament Injuries in Wakeboarding

    PubMed Central

    Starr, Harlan M.; Sanders, Brett

    2012-01-01

    Background: Wakeboarding is an increasingly popular sport that involves aggressive stunts with high risk for lower extremity injury, including anterior cruciate ligament (ACL) rupture. Little has been reported on prevalence or mechanism of ACL injury while wakeboarding. Hypothesis: The prevalence of ACL injury in wakeboarding approaches that of other high-risk sports. Analyzing the mechanism of ACL injury may aid in future efforts of prevention. Study Design: Descriptive epidemiology study. Methods: In sum, 1580 surveys were sent internationally to professional and amateur wakeboarders. The survey questioned the participants on their history of an ACL tear while wakeboarding and asked them to describe the mechanism of injury and treatment. Results: A total of 123 surveys were returned. Of this group, 52 (42.3%) acknowledged having had an ACL tear while wakeboarding. The majority described feeling a pop or buckle after attempting to land a high jump. Only 5 participants (13.5%) described a rotational mechanism created by catching the board edge in the water. Thirty-seven participants (71.15%) said that the injury ruined their ability to wakeboard before reconstruction, and 41 (78.85%) had the injury repaired surgically. Conclusion: The prevalence of ACL tears in this data set, 42.3%, is the highest reported in the literature for wakeboarding and one of the highest for any sport. The main mechanism of injury appears to involve axial compression while one lands in a provocative position; it is not related to a rotational force created by fixed bindings. The injury should be surgically repaired to effectively continue the sport. Further study is needed to determine if wakeboarding represents a high-risk sport for ACL injury. Clinical Significance: Wakeboarding may be a high-risk sport for ACL injury. Noncontact axial compression appears to be the main mechanism of injury. PMID:23016104

  7. Balser plate stabilization: an alternate therapy for traumatic sternoclavicular instability.

    PubMed

    Franck, Wolfgang M; Jannasch, Olof; Siassi, Michael; Hennig, Friedrich F

    2003-01-01

    Traumatic instability of the sternoclavicular joint is a rare condition. It can be treated by surgical cerclage fixation, which necessitates postoperative immobilization, an approach preventing early postoperative functional rehabilitation. Balser plate stabilization is a therapeutic alternative that does not require extended periods of immobilization. From January 1, 1996, to December 31, 2000, a total of 10 trauma patients with unstable sternoclavicular joints (Allman grade III) requiring surgical management were treated with Balser plate stabilization to allow early physiotherapy. The population included 7 patients with anterior dislocations, 2 with posterior dislocations, and 1 with medial epiphysiolysis in addition to posterior dislocation. Implants were removed from 9 patients after 3 months and 1 patient after 2 months. One year or longer after the procedure, 9 of 10 patients were available for follow-up; 1 patient had moved. The results achieved with this alternative treatment are excellent. There were no cases of redislocation. The only surgical complication was a seroma that required surgical drainage. One patient had arthrosis develop. Outcome was assessed with Constant (range, 84-100; mean, 90.2 +/- 6.6) and DASH (disabilities of the arm, shoulder, and hand) (range, 4.1-16.6; mean, 8.4 +/- 1.4) scores. For the rare case of sternoclavicular joint dislocation requiring open surgical reduction and stabilization, the Balser plate technique is reliable, permits early movement, has good postoperative results, and compares favorably with alternative methods. PMID:12851582

  8. The anterior insular and anterior cingulate cortices in emotional processing for self-face recognition.

    PubMed

    Morita, Tomoyo; Tanabe, Hiroki C; Sasaki, Akihiro T; Shimada, Koji; Kakigi, Ryusuke; Sadato, Norihiro

    2014-05-01

    Individuals can experience embarrassment when exposed to self-feedback images, depending on the extent of the divergence from the internal representation of the standard self. Our previous work implicated the anterior insular cortex (AI) and the anterior cingulate cortex (ACC) in the processing of embarrassment; however, their exact functional contributions have remained uncertain. Here, we explored the effects of being observed by others while viewing self-face images on the extent of embarrassment, and the activation and connectivity patterns in the AI and ACC. We conducted functional magnetic resonance imaging hyperscanning in pairs of healthy participants using an interaction system that allowed an individual to be observed by a partner in real time. Being observed increased the extent of embarrassment reported when viewing self-face images; a corresponding increase in self-related activity in the right AI suggested that this region played a direct role in the subjective experience. Being observed also increased the functional connectivity between the caudal ACC and prefrontal regions, which are involved in processing the reflective self. The ACC might therefore serve as a hub, integrating information about the reflective self that is used in evaluating perceptual self-face images. PMID:23377900

  9. The anterior insular and anterior cingulate cortices in emotional processing for self-face recognition

    PubMed Central

    Morita, Tomoyo; Tanabe, Hiroki C.; Sasaki, Akihiro T.; Shimada, Koji; Kakigi, Ryusuke

    2014-01-01

    Individuals can experience embarrassment when exposed to self-feedback images, depending on the extent of the divergence from the internal representation of the standard self. Our previous work implicated the anterior insular cortex (AI) and the anterior cingulate cortex (ACC) in the processing of embarrassment; however, their exact functional contributions have remained uncertain. Here, we explored the effects of being observed by others while viewing self-face images on the extent of embarrassment, and the activation and connectivity patterns in the AI and ACC. We conducted functional magnetic resonance imaging hyperscanning in pairs of healthy participants using an interaction system that allowed an individual to be observed by a partner in real time. Being observed increased the extent of embarrassment reported when viewing self-face images; a corresponding increase in self-related activity in the right AI suggested that this region played a direct role in the subjective experience. Being observed also increased the functional connectivity between the caudal ACC and prefrontal regions, which are involved in processing the reflective self. The ACC might therefore serve as a hub, integrating information about the reflective self that is used in evaluating perceptual self-face images. PMID:23377900

  10. REMNANTS OF THE ANTERIOR TUNICA VASCULOSA LENTIS AND LONG ANTERIOR LENS ZONULES

    PubMed Central

    Roberts, Daniel K.; Newman, Tricia L.; Roberts, Mary F.; Wilensky, Jacob T.

    2013-01-01

    Purpose To investigate presence of remnants of the tunica vasculosa lentis, a possible indication of anterior segment dysgenesis, in subjects with the long anterior zonule (LAZ) trait. Methods Retro-illumination photos of the pupil region had been collected in earlier study of the LAZ trait in African-Americans. Secondary image analysis was performed to assess the frequency of intact persistent pupillary membrane iris strands (PPMIS). Results The analysis included 148 subjects, comprised of 74 LAZ subjects (median age=70 years, range=50–91 years; 64 females) and 74 controls (68 years, 50–83 years; 64 females). While controlling for age and gender, analysis showed that LAZ subjects were 3.1 times more likely than controls (OR=3.1; 95% CI =1.4 to 6.7; P=0.004) to exhibit PPMIS in at least one of their eyes. Conclusions The LAZ trait, which is being studied as a potential risk factor for glaucoma, was associated with presence of PPMIS in our study population. PMID:23708424

  11. Delayed chromosomal instability induced by DNA damage.

    PubMed Central

    Marder, B A; Morgan, W F

    1993-01-01

    DNA damage induced by ionizing radiation can result in gene mutation, gene amplification, chromosome rearrangements, cellular transformation, and cell death. Although many of these changes may be induced directly by the radiation, there is accumulating evidence for delayed genomic instability following X-ray exposure. We have investigated this phenomenon by studying delayed chromosomal instability in a hamster-human hybrid cell line by means of fluorescence in situ hybridization. We examined populations of metaphase cells several generations after expanding single-cell colonies that had survived 5 or 10 Gy of X rays. Delayed chromosomal instability, manifested as multiple rearrangements of human chromosome 4 in a background of hamster chromosomes, was observed in 29% of colonies surviving 5 Gy and in 62% of colonies surviving 10 Gy. A correlation of delayed chromosomal instability with delayed reproductive cell death, manifested as reduced plating efficiency in surviving clones, suggests a role for chromosome rearrangements in cytotoxicity. There were small differences in chromosome destabilization and plating efficiencies between cells irradiated with 5 or 10 Gy of X rays after a previous exposure to 10 Gy and cells irradiated only once. Cell clones showing delayed chromosomal instability had normal frequencies of sister chromatid exchange formation, indicating that at this cytogenetic endpoint the chromosomal instability was not apparent. The types of chromosomal rearrangements observed suggest that chromosome fusion, followed by bridge breakage and refusion, contributes to the observed delayed chromosomal instability. Images PMID:8413263

  12. Baroclinic instability in stellar radiation zones

    SciTech Connect

    Kitchatinov, L. L.

    2014-03-20

    Surfaces of constant pressure and constant density do not coincide in differentially rotating stars. Stellar radiation zones with baroclinic stratification can be unstable. Instabilities in radiation zones are of crucial importance for angular momentum transport, mixing of chemical species, and, possibly, for magnetic field generation. This paper performs linear analysis of baroclinic instability in differentially rotating stars. Linear stability equations are formulated for differential rotation of arbitrary shape and then solved numerically for rotation nonuniform in radius. As the differential rotation increases, r- and g-modes of initially stable global oscillations transform smoothly into growing modes of baroclinic instability. The instability can therefore be interpreted as stability loss to r- and g-modes excitation. Regions of stellar parameters where r- or g-modes are preferentially excited are defined. Baroclinic instability onsets at a very small differential rotation of below 1%. The characteristic time of instability growth is about 1000 rotation periods. Growing disturbances possess kinetic helicity. Magnetic field generation by the turbulence resulting from baroclinic instability in differentially rotating radiation zones is therefore possible.

  13. Radiative heat transport instability in ICF plasmas

    NASA Astrophysics Data System (ADS)

    Rozmus, W.; Bychenkov, V. Yu.

    2015-11-01

    A laser produced high-Z plasma in which an energy balance is achieved due to radiation losses and radiative heat transfer supports ion acoustic wave instability. A linear dispersion relation is derived and instability is compared to the radiation cooling instability. This instability develops in the wide range of angles and wavenumbers with the typical growth rate on the order of cs/LT (cs is the sound speed, LT is the temperature scale length). In addition to radiation dominated systems, a similar thermal transport driven ion acoustic instability was found before in plasmas where the thermal transport coefficient depends on electron density. However, under conditions of indirect drive ICF experiments the driving term for the instability is the radiative heat flux and in particular, the density dependence of the radiative heat conductivity. A specific example of thermal Bremsstrahlung radiation source has been considered corresponding to a thermal conductivity coefficient that is inversely proportional to the square of local particle density. In the nonlinear regime this instability may lead to plasma jet formation and anisotropic x-ray generation.

  14. Anterior clinoid mucocele presenting with orbital apex syndrome

    PubMed Central

    Wang, Anthony C.; Than, Khoi D.; Ramnath, Suresh; Pandey, Aditya S.

    2013-01-01

    Background: Pneumatized anterior clinoid process is a common anatomic variant. Mucocele formation is a known complication of clinoid drilling during certain intracranial operations; however, mucoceles of pneumatized anterior clinoid processes have been found to spontaneously occur. Case Description: A 44-year-old male presented with complaints of left-sided retro-orbital pain, double vision, and numbness over the upper face and scalp on the left side of 1-week duration. On examination, he was found to develop cranial nerve III, IV, and VI palsies with pupillary sparing, ophthalmic division cranial nerve V dysfunction, and eventually, the onset of vision loss. Conclusions: We report a case of spontaneous anterior clinoid process mucocele presenting with orbital apex syndrome. This was treated successfully with anterior clinoidectomy for decompression. PMID:23772333

  15. Anterior vaginal wall repair (surgical treatment of urinary incontinence) - slideshow

    MedlinePlus

    ... page: //medlineplus.gov/ency/presentations/100110.htm Anterior vaginal wall repair (surgical treatment of urinary incontinence) - series ... 4 out of 4 Normal anatomy Overview The vaginal opening lies just below the urethral opening, and ...

  16. Involuntary masturbation and hemiballismus after bilateral anterior cerebral artery infarction.

    PubMed

    Bejot, Yannick; Caillier, Marie; Osseby, Guy-Victor; Didi, Roy; Ben Salem, Douraied; Moreau, Thibault; Giroud, Maurice

    2008-02-01

    Ischemia of the areas supplied by the anterior cerebral artery is relatively uncommon. In addition, combined hemiballismus and masturbation have rarely been reported in patients with cerebrovascular disease. We describe herein a 62-year-old right-handed man simultaneously exhibiting right side hemiballismus and involuntary masturbation with the left hand after bilateral infarction of the anterior cerebral artery territory. Right side hemiballismus was related to the disruption of afferent fibers from the left frontal lobe to the left subthalamic nucleus. Involuntary masturbation using the left hand was exclusively linked to a callosal type of alien hand syndrome secondary to infarction of the right side of the anterior corpus callosum. After 2 weeks, these abnormal behaviours were completely extinguished. This report stresses the wide diversity of clinical manifestations observed after infarction of the anterior cerebral artery territory. PMID:17961914

  17. Memory-guided attention in the anterior thalamus.

    PubMed

    Leszczyński, Marcin; Staudigl, Tobias

    2016-07-01

    The anterior thalamus is densely connected with both the hippocampus and the prefrontal cortex. It is known to play a role in learning and episodic memory. Given its connectivity profile with the prefrontal cortex, it may also be expected to contribute to executive functions. Recent studies in both rodents and humans add to our understanding of anterior thalamic function, suggesting that it is a key region for allocating attention. We discuss the convergence between studies in rodents and humans, both of which imply that the anterior thalamus may play a key role in memory-guided attention. We suggest that efficient allocation of attention to memory representations requires interaction between the memory-related hippocampal and the attention related fronto-parietal networks. We further propose that the anterior thalamus is a hub that connects and modulates both systems. PMID:27130694

  18. Elevator Muscle Anterior Resection: A New Technique for Blepharoptosis.

    PubMed

    Zigiotti, Gian Luigi; Delia, Gabriele; Grenga, Pierluigi; Pichi, Francesco; Rechichi, Miguel; Jaroudi, Mahmoud O; d'Alcontres, Francesco Stagno; Lupo, Flavia; Meduri, Alessandro

    2016-01-01

    Blepharoptosis is a condition of inadequate upper eyelid position, with a downward displacement of the upper eyelid margin resulting in obstruction of the superior visual field. Levator resection is an effective technique that is routinely used to correct aponeurotic ptosis. The anterior levator resection is the procedure of choice in moderate blepharoptosis when there is moderate to good levator muscle function, furthermore, with an anterior approach, a greater resection can be achieved than by a conjunctival approach. The authors describe a modification in the Putterman technique with a resection done over a plicated elevator, plication that was suggested by Mustardè. The technique has been named as elevator muscle anterior resection. The elevator muscle anterior resection inspires from the Fasanella-Servat operation by the use of a clamp, making the operation simple and predictable. PMID:26703054

  19. The Role of Anterior Segment Optical Coherence Tomography in Glaucoma

    PubMed Central

    Salim, Sarwat

    2012-01-01

    The anterior segment optical coherence tomography provides an objective method to assess the anterior segment of the eye, including the anatomy of the anterior chamber angle. This technology allows both qualitative and quantitative analyses of the angle and has shown potential in detecting and managing angle-closure glaucoma. In addition, it has a role in identifying pathology in some forms of secondary open-angle glaucoma and postsurgical management of glaucoma. Limitations of this technology include its cost and inability to visualize well structures posterior to the iris, such as the ciliary body. This paper focuses on potential benefits and limitations of anterior segment optical coherence tomography when compared with conventional gonioscopy and ultrasound biomicroscopy. Various clinical entities will be described to discuss its potential role in glaucoma practice. PMID:22900146

  20. Anterior chamber volume. Its measurement and clinical application.

    PubMed

    Coakes, R L; Lloyd-Jones, D; Hitchings, R A

    1979-04-01

    Measurement of anterior chamber volume is discussed and attention drawn to a new, convenient slit-image method, which was used to study anterior chamber depth and volume before and after prophylactic peripheral iridectomy in the fellow eyes of patients presenting with unilateral acute angle-closure glaucoma. There was no significant change in depth after iridectomy but the mean anterior chamber volume increased significantly (P less than 0.01), by nearly 3 per cent. This increase was due to elimination of peripheral iris bombé which was not present in two control groups of normal eyes, one matched for anterior chamber depth and the other for age and refraction. Peripheral iris bombé may be a quantifiable factor predisposing to the development of acute angle-closure glaucoma. PMID:297385

  1. Minimally invasive surgery of the anterior skull base: transorbital approaches

    PubMed Central

    Gassner, Holger G.; Schwan, Franziska; Schebesch, Karl-Michael

    2016-01-01

    Minimally invasive approaches are becoming increasingly popular to access the anterior skull base. With interdisciplinary cooperation, in particular endonasal endoscopic approaches have seen an impressive expansion of indications over the past decades. The more recently described transorbital approaches represent minimally invasive alternatives with a differing spectrum of access corridors. The purpose of the present paper is to discuss transorbital approaches to the anterior skull base in the light of the current literature. The transorbital approaches allow excellent exposure of areas that are difficult to reach like the anterior and posterior wall of the frontal sinus; working angles may be more favorable and the paranasal sinus system can be preserved while exposing the skull base. Because of their minimal morbidity and the cosmetically excellent results, the transorbital approaches represent an important addition to established endonasal endoscopic and open approaches to the anterior skull base. Their execution requires an interdisciplinary team approach. PMID:27453759

  2. Treatment of chronic anterior locked glenohumeral dislocation with hemiarthroplasty

    PubMed Central

    Nicolas, Andrea Pujol; Liow, Raymond

    2014-01-01

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

  3. Tidal instability in a rotating heated core

    NASA Astrophysics Data System (ADS)

    Cebron, D.; Maubert, P.; Le Bars, M.

    2011-12-01

    The tidal (or elliptical) instability comes from a triadic parametric resonance between two inertial waves of a rotating fluid and an imposed elliptic deformation. Previous studies of this instability have been conducted with an isothermal fluid. Nevertheless, in all natural systems, temperature differences are also present, which lead to stratification or to convection. The previous studies need then to be reinvestigated in order to quantify the impact of a temperature field on the elliptical instability. Conversely, from a thermal point of view, many studies have been performed regarding the convective flow of an incompressible homogeneous fluid in a rotating spherical shell. However, since most astrophysical bodies are tidally deformed, these studies have to be reinvestigated to account for the potential presence of an elliptical instability. Note that this is different from the direct resonance of a forced gravito-inertial wave considered by Kumazawa et al. (1994). The guideline of our study is given by the following questions: (i) how is the growth rate of the tidal instability modified by an imposed temperature difference in an ellipsoidal geometry? (ii) Does the tidal instability grow over an established convective flow? (iii) Is the heat flux modified by the instability, and what are the scaling laws involved? In this work, we tackle these questions using a systematic numerical study of the thermo-elliptical rotating flow in a fixed triaxial ellipsoidal shell. In particular, we validate general physical processes of direct relevance for planetary dynamics. We demonstrate also that the tidal instability can grow on a convective flow, and may disrupt the famous Busse columns in planetary cores. Finally, we show that the heat flux at planetary scales may be controlled by the forced convection due to this tidal instability, which in any case plays a fundamental role in the organization of fluid motions. Kumazawa, M., Yoshida, S., Ito, T., Yoshioka, H., 1994

  4. Widnall instabilities in vortex pairs

    NASA Astrophysics Data System (ADS)

    Sipp, Denis; Jacquin, Laurent

    2003-07-01

    In this article we analyze the cooperative three-dimensional short-wave instabilities developing on concentrated vortex dipoles that have been obtained by means of two-dimensional direct numerical simulations. These dipoles are characterized by their aspect ratio a/b where a is the radius of the vortices based on the polar moments of vorticity and b is the separation between the vortex centroids. In the inviscid case, we show that the selection of the antisymmetric eigenmode smoothly increases with a/b: for a/b=0.208, the amplification rate of the antisymmetric eigenmode is only 1.4% larger than the amplification rate of the symmetric eigenmode. When a/b=0.288, this difference increases up to 7%. The results of the normal mode analysis may be compared to those of an asymptotic stability analysis of a Lamb-Oseen vortex subjected to a weak straining field, following Moore and Saffman [Proc. R. Soc. London, Ser. A 346, 413 (1975)]. This theory shows that the instability may occur whenever two Kelvin waves exist with the same frequency ω, the same axial wavenumber k and with azimuthal wavenumbers m and m+2. Contrary to the case of a Rankine vortex [Tsai and Widnall, J. Fluid Mech. 73, 721 (1976)], the presence of critical layers in a Lamb-Oseen vortex prevents a large number of possible resonances. For example, resonances between m=-2 and m=0 modes lead to damped modes. The only resonances that occur are related to the stationary (ω=0) bending waves (m=±1) obtained for specific values of the axial wavenumber. All these predictions are found to be in good agreement with the results obtained by the stability analysis of the considered vortex pairs. At last, we present a nonautonomous amplitude equation which takes into account all effects of viscosity, i.e., the viscous damping of the amplification rate of the perturbation but also the increase of the dipole aspect ratio a/b due to the viscous diffusion of the basic flowfield. The low-Reynolds number experiment of

  5. Estradiol Upregulates c-FLIPlong Expression in Anterior Pituitary Cells.

    PubMed

    Jaita, G; Zárate, S; Ferraris, J; Gottardo, M F; Eijo, G; Magri, M L; Pisera, D; Seilicovich, A

    2016-04-01

    Anterior pituitary cell turnover depends on a tight balance between proliferation and apoptosis. We have previously shown that estrogens sensitize anterior pituitary cells to pro-apoptotic stimuli. c-FLIP (cellular-FLICE-inhibitory-protein) isoforms are regulatory proteins of apoptosis triggered by death receptors. c-FLIPshort isoform competes with procaspase-8 inhibiting its activation. However, c-FLIPlong isoform may have a pro- or anti-apoptotic function depending on its expression level. In the present study, we explored whether estrogens modulate c-FLIP expression in anterior pituitary cells from ovariectomized (OVX) rats and in GH3 cells, a somatolactotrope cell line. Acute administration of 17β-estradiol to OVX rats increased c-FLIPlong expression in the anterior pituitary gland without changing c-FLIPshort expression as assessed by Western blot. Estradiol in vitro also increased c-FLIPlong expression in anterior pituitary cells but not in GH3 cells. As determined by flow cytometry, the percentage of anterior pituitary cells expressing c-FLIP was higher than in GH3 cells. However, c-FLIP fluorescence intensity in GH3 cells was higher than in anterior pituitary cells. FasL increased the percentage of TUNEL-positive GH3 cells incubated either with or without estradiol suggesting that the pro-apoptotic action of Fas activation is estrogen-independent. Our results show that unlike what happens in nontumoral pituitary cells, estrogens do not modulate either c-FLIPlong expression or FasL-induced apoptosis in GH3 cells. The stimulatory effect of estradiol on c-FLIPlong expression could be involved in the sensitizing effect of this steroid to apoptosis in anterior pituitary cells. The absence of this estrogenic action in tumor pituitary cells could be involved in their tumor-like behavior. PMID:26566102

  6. Extradural Dermoid Cyst of the Anterior Infratemporal Fossa. Case Report

    PubMed Central

    Watanabe, Kentaro; Filomena, Carol A.; Nonaka, Yoichi; Matsuda, Masahide; Zomorodi, Ali R.; Friedman, Allan H.; Fukushima, Takanori

    2015-01-01

    Dermoid cysts are rare in the skull base. There have been 10 reported cases of dermoid cysts in the cavernous sinus, two in the petrous apex, and one in the extradural Meckel cave. This is the first case report of a dermoid cyst in the anterior infratemporal fossa attached to the anterior dura of the foramen ovale. The clinical presentation, radiologic findings, histologic features, tumor origin, and operative technique are described along with a review of the literature. PMID:26623226

  7. Frontosphenoid synostosis: an unusual cause of anterior plagiocephaly.

    PubMed

    Bot, Gyang; Leshem, David; Shiran, Shelly I; Ben-Shachar, Shay; Constantini, Shlomi; Roth, Jonathan

    2015-01-01

    Nonpositional anterior plagiocephaly results commonly from unilateral coronal craniosynostosis. We present 2 patients of a rare cause of anterior plagiocephaly known as frontosphenoid synostosis. This condition is characterized by the absence of a harlequin eye (or the harlequin sign on computed tomography), which is usually present in unilateral coronal synostosis. We also observed no reduction in the ear-eye distance, which can distinguish it from coronal craniosynostosis. PMID:25469893

  8. Anterior cerebral artery territory infarctions presenting with ascending tetraparesis.

    PubMed

    Okamoto, Kensho; Hamada, Eri; Okuda, Bungo

    2004-01-01

    We describe a patient with ascending tetraparesis following stroke. The patient presented initially with spastic paraparesis which acutely evolved to tetraparesis with abulia. Magnetic resonance imaging revealed acute infarctions in the bilateral medial frontal regions but not in the brainstem or spinal cord. Multiple infarctions in the anterior cerebral artery territory appeared to originate from artery to artery embolism. The present case provides distinct clinical features of anterior cerebral artery syndrome which mimic myelopathy or brainstem lesions. PMID:17903956

  9. A drift model of interchange instability

    SciTech Connect

    Benilov, E. S.; Power, O. A.

    2007-08-15

    A set of asymptotic equations is derived, describing the dynamics of the flute mode in a magnetized plasma with cold ions, under a 'local' approximation (i.e., near a particular point). The asymptotic set is then used to calculate the growth rate of interchange instability in the slab model. It is shown that, unlike the magnetohydrodynamic ordering, the drift one allows instability to occur for either sign of the pressure gradient (i.e., for both 'bad' and 'good' curvature of the magnetic field). It is also demonstrated that finite beta gives rise to an extra instability that does not exist in the small-beta limit.

  10. A new instability of Saturn's ring

    NASA Technical Reports Server (NTRS)

    Goertz, C. K.; Morfill, G.

    1988-01-01

    Perturbations in the Saturn ring's mass density are noted to be prone to instabilities through the sporadic elevation of submicron-size dust particles above the rings, which furnishes an effective angular momentum exchange between the rings and Saturn. The dust thus elevated from the ring settles back onto it at a different radial distance. The range of wavelength instability is determinable in light of the dust charge, the average radial displacement of the dust, and the fluctuation of these quantities. It is suggested that at least some of the B-ring's ringlets may arise from the instability.

  11. Inviscid instability of streamwise corner flow

    NASA Technical Reports Server (NTRS)

    Balachandar, S.; Malik, M. R.

    1993-01-01

    Linear stability of the incompressible flow along a stream wise corner is studied by solving the two-dimensional eigenvalue problem governed by partial differential equations. It is found that this fully three-dimensional flow is subject to inviscid instability due to the inflectional nature of the stream wise velocity profile. The higher growth rates for the inviscid instability mode, which is symmetric about the corner bisector, as compared to the viscous Tollmien-Schlichting instability operative away from the corner is consistent with the experimental findings that the corner flow transitions to turbulence earlier than the two-dimensional Blasius flow away from the corner.

  12. Understanding carpal instability: a radiographic perspective.

    PubMed

    Kani, Kimia Khalatbari; Mulcahy, Hyojeong; Chew, Felix S

    2016-08-01

    The wrist is disposed to a variety of instability patterns owing to its complex anatomical and biomechanical properties. Various classification schemes have been proposed to describe the different patterns of carpal instability, of which the Mayo classification is the most commonly used. Understanding the concepts and pertinent terminology of this classification scheme is important for the correct interpretation of images and optimal communication with referring physicians. Standard wrist radiographs are the first line of imaging in carpal instability. Additional information may be obtained with the use of stress radiographs and other imaging modalities. PMID:27085694

  13. Three-dimensional instability of elliptical flow

    NASA Astrophysics Data System (ADS)

    Bayly, B. J.

    1986-10-01

    A clarification of the physical and mathematical nature of Pierrhumbert's (1986) three-dimensional short-wave inviscid instability of simple two-dimensional elliptical flow is presented. The instabilities found are independent of length scale, extending Pierrhumbert's conclusion that the structures of the instabilities are independent of length scale in the limit of large wave number. The fundamental modes are exact solutions of the nonlinear equations, and they are plane waves whose wave vector rotates elliptically around the z axis with a period of 2(pi)/Omega. The growth rates are shown to be the exponents of a matrix Floquet problem, and good agreement is found with previous results.

  14. Mode instabilities: physical origin and mitigation strategies

    NASA Astrophysics Data System (ADS)

    Jauregui, Cesar; Otto, Hans-Jürgen; Jansen, Florian; Stutzki, Fabian; Eidam, Tino; Limpert, Jens; Tünnermann, Andreas

    2013-03-01

    The phenomenon of mode instabilities has quickly become the most limiting effect for a further scaling of the average power of fiber laser systems. It is important to get a detailed understanding of its physical origin in order to develop efficient mitigation strategies. In this work we present an analysis of the different physical processes that give rise to mode instabilities and reveal that thermally-induced non-adiabatic waveguide changes play a key role. With this insight in the physical processes underlying mode instabilities a semi-analytic formula is obtained and several mitigation guidelines will be presented and discussed.

  15. Rational instability in the natural coalition forming

    NASA Astrophysics Data System (ADS)

    Vinogradova, Galina; Galam, Serge

    2013-12-01

    The work aims to investigate a paradigm of instability in coalition forming among countries, using a model inspired from Statistical Physics. The instability is a consequence of decentralized maximization of the individual benefits where contradictory associations into coalitions occur due to independent evolution of pairwise propensity bonds. In contrast to the existing literature we analyze the phenomena within a long horizon rationality of actors. This allows to explore the complex behaviors and phenomena such as instability, infinite cycling and non-optimal stability. Along with the formal implementation, we illustrate the phenomena in a multi-thread simulation created for this aim, and provide analysis of several real cases including the Eurozone.

  16. Rayleigh-Taylor instability in binary condensates

    SciTech Connect

    Gautam, S.; Angom, D.

    2010-05-15

    We propose a well-controlled experimental scheme to initiate and examine the Rayleigh-Taylor instability in two-species Bose-Einstein condensates. We identify the {sup 85}Rb-{sup 87}Rb mixture as an excellent candidate to observe experimentally. The instability is initiated by tuning the {sup 85}Rb-{sup 85}Rb interaction through a magnetic Feshbach resonance. We show that the observable signature of the instability is the damping of the radial oscillations. We also propose a semianalytic scheme to determine the stationary state of binary condensates with the Thomas-Fermi approximation for axisymmetric traps.

  17. Anterior muscle sparing approach for total hip arthroplasty

    PubMed Central

    Moskal, Joseph T; Capps, Susan G; Scanelli, John A

    2013-01-01

    The purpose of this review is to examine the validity of positive claims regarding the direct anterior approach (DAA) with a fracture table for total hip arthroplasty. Recent literature regarding the DAA was searched and specific claims investigated including improved early outcomes, speed of recovery, component placement, dislocation rates, and complication rates. Recent literature is positive regarding the effects of total hip arthroplasty with the anterior approach. While the data is not definitive at present, patients receiving the anterior approach for total hip arthroplasty tend to recover more quickly and have improved early outcomes. Component placement with the anterior approach is more often in the “safe zone” than with other approaches. Dislocation rates tend to be less than 1% with the anterior approach. Complication rates vary widely in the published literature. A possible explanation is that the variance is due to surgeon and institutional experience with the anterior approach procedure. Concerns remain regarding the “learning curve” for both surgeons and institutions. In conclusion, it is not a matter of should this approach be used, but how should it be implemented. PMID:23362470

  18. Computational modelling of mobile bearing TKA anterior-posterior dislocation.

    PubMed

    Müller, J H; Zakaria, T; van der Merwe, W; D'Angelo, F

    2016-01-01

    Anterior-posterior stability in an unconstrained mobile-bearing total knee arthroplasty (TKA) and one with rotational constraints is compared in a computational model based on an ASTM test. Both TKA designs dislocate at loads greater than reported maximum in vivo forces. The posterior drawer forces (mean: 3027 N vs. 1817 N) needed to induce subluxation increase with a greater anterior jump distance (12 mm vs. 7 mm; refers to the vertical height of the anterior or posterior border of the tibial insert's articulating surface). The posterior jump distance for both tested TKA differed by 1.5 mm and had minimal effect on the magnitude of the anterior drawer forces at dislocation in mid-flexion (unconstrained vs. constrained: 445 N vs. 412 N). The unconstrained insert dislocated by means of spin-out whereas in the constrained TKA the femur dislocated from the bearing during posterior drawer and the bearing from the baseplate during anterior drawer. MCL function is an important consideration during ligament balancing since a ± 10% variation in MCL tension affects dislocation forces by ± 20%. The simulation platform provided the means to investigate TKA designs in terms of anterior-posterior stability as a function of knee flexion, collateral ligament function and mechanical morphology. PMID:26047039

  19. Torque control during lingual anterior retraction without posterior appliances

    PubMed Central

    Mo, Sung-Seo; Sung, Sang-Jin; Chung, Kyu-Rhim; Chun, Yun-Sic; Kook, Yoon-Ah; Nelson, Gerald

    2013-01-01

    Objective To evaluate the factors that affect torque control during anterior retraction when utilizing the C-retractor with a palatal miniplate as an exclusive source of anchorage without posterior appliances. Methods The C-retractor was modeled using a 3-dimensional beam element (0.9-mm-diameter stainless-steel wire) attached to mesh bonding pads. Various vertical heights and 2 attachment positions for the lingual anterior retraction hooks (LARHs) were evaluated. A force of 200 g was applied from each side hook of the miniplate to the splinted segment of 6 or 8 anterior teeth. Results During anterior retraction, an increase in the LARH vertical height increased the amount of lingual root torque and intrusion of the incisors. In particular, with increasing vertical height, the tooth displacement pattern changed from controlled tipping to bodily displacement and then to lingual root displacement. The effects were enhanced when the LARH was located between the central and lateral incisors, as compared to when the LARH was located between the lateral incisors and canines. Conclusions Three-dimensional lingual anterior retraction of the 6 or 8 anterior teeth can be accomplished using the palatal miniplate as the only anchorage source. Using LARHs at different heights or positions affects the quality of torque and intrusion. PMID:23502971

  20. Direct anterior total hip arthroplasty: Comparative outcomes and contemporary results

    PubMed Central

    Connolly, Keith P; Kamath, Atul F

    2016-01-01

    Direct anterior total hip arthroplasty has become increasingly more popular among arthroplasty surgeons, in large part due to the use of an intramuscular interval and desire to reduce soft tissue damage. Several studies have now been published comparing the anterior intramuscular to other commonly used approaches, and many studies have published complication rates on large series of patients. Review of comparative studies indicates direct anterior hips tend towards shorter hospital stays and high rates of patients discharged to home. Although some studies show evidence of early benefit in functional outcomes, there is no strong evidence that the anterior approach provides any long term functional improvements compared to other approaches. Additionally, evidence to support reduced damage to soft tissue may not translate to certain clinical significance. Rates of intra-operative femur fracture, operative time and blood loss rates are notably higher for those developing familiarity with this approach. However, when surgeons have performed a modest number of procedures, the complication rates tend to markedly decrease in most studies to levels comparable to other approaches. Accuracy of component positioning also favors the anterior approach in some studies. This review summarizes the available literature comparing the direct anterior to other approaches for total hip arthroplasty and provides a comprehensive summary of common complications. PMID:26925380