History Of Shoulder Instability Research Articles

Outcomes of Shoulder Instability Surgery in Competitive Wrestlers: Outcomes, Reoperations, and Return to Play at 5 Years’ Mean Follow-up

Background: Wrestling is a physically demanding sport with young athletes prone to traumatic shoulder instability and a paucity of data evaluating the results of shoulder instability surgery (SIS). Purpose: To assess reoperation rates, patient-reported outcomes, and return to wrestling (RTW) after SIS in a cohort of competitive wrestlers. Study Design: Case series; Level of evidence, 3. Methods: All competitive wrestlers with a history of shoulder instability and subsequent surgery at a single institution between 1996 and 2020 were identified. All directions of shoulder instability (anterior shoulder instability [ASI], posterior shoulder instability [PSI], and traumatic multidirectional shoulder instability [TMDI]) were analyzed. Exclusions included revision SIS and <2 years of follow-up. Athletes were contacted for determination of complications, RTW, and Western Ontario Shoulder Instability Index scores. Results: Ultimately, 104 wrestlers were included with a mean age at initial instability of 16.9 years (range, 12.0-22.7 years), mean age at surgery of 18.9 years (range, 14.0-29.0 years), and a mean follow-up of 5.2 years (range, 2.0-22.0 years). A total of 58 (55.8%) wrestlers were evaluated after a single shoulder instability event, while 46 (44.2%) sustained multiple events before evaluation. ASI was the most common direction (n = 79; 76.0%), followed by PSI (n = 14; 13.5%) and TMDI (n = 11; 10.6%). Surgical treatment was most commonly an arthroscopic soft tissue stabilization (n = 88; 84.6%), with open soft tissue repair (n = 13; 12.5%) and open bony augmentation (n = 3; 2.9%) performed less frequently. RTW occurred in 57.3% of wrestlers at a mean of 9.8 months. Recurrent instability was the most common complication, occurring in 18 (17.3%) wrestlers. Revision SIS was performed in 15 (14.4%) wrestlers. Across the entire cohort, survivorship rates free from recurrent instability and revision surgery were 90.4% and 92.5% at 2 years, 71.9% and 70.7% at 5 years, and 71.9% and 66.5% at 10 years, respectively. Preoperative recurrent instability was an independent risk factor for postoperative recurrent instability (hazard ratio, 3.8; 95% CI, 1.33-11.03; P = .012). Conclusion: Competitive wrestlers with multiple dislocations before initial clinical evaluation were 3.8 times more likely to experience postoperative recurrent instability. Patients should be counseled that despite SIS, only 57.3% returned to wrestling after surgery.

A History of Shoulder Instability is More Common in Young Patients Undergoing Total Shoulder Arthroplasty.

Previous studies have shown an association between shoulder instability and the development of glenohumeral arthritis leading to total shoulder arthroplasty (TSA). The primary goal of this study was to evaluate if a history of shoulder instability was more common in patients under 50 years old undergoing TSA. The secondary objective was to determine if a history of prior surgical stabilization is more common in patients under 50 years old undergoing TSA. Using the military health system data repository (MDR) and the Military Analysis and Reporting Tool (M2), we identified 489 patients undergoing primary TSA from October 1, 2013, to May 1, 2020, within the Military Health System (MHS). Patients under 50 years old were matched 1:2 with patients 50 years and older based on sex, race, and military status, with the final study population comprising 240 patients who underwent primary TSA during the study period. Electronic medical records were examined, and factors showing univariate association p < 0.2 were included in a binary logistic regression analysis to determine associations between demographic/clinical factors and TSA prior to 50 years old. The groups differed significantly in shoulder arthritis subtype, with the older group having significantly more primary osteoarthritis (78% vs. 51%, p<0.001). The younger group had significantly more patients with a history of shoulder instability (48% vs. 12%, p<0.001), prior ipsilateral shoulder surgery of any type (74% vs. 34%, p<0.001), and prior ipsilateral shoulder stabilization surgery (31% vs. 5%, p<0.001). In the resultant logistic regression model, a history of shoulder instability (OR 5.0, p < .001) and a history of any prior ipsilateral shoulder surgery (OR 3.5, p<.001) were associated with TSA prior to the age of 50 years old. Shoulder instability is a risk factor for TSA before 50 years old. It is unclear how surgical stabilization influences the development of secondary glenohumeral arthritis in shoulder instability. Patients should be counseled that recurrent instability could lead to earlier TSA, regardless of whether surgical stabilization is performed.

Impact of age on glenoid size: three-dimensional computed tomographic analysis of glenoid anatomy

ObjectivePredictors of glenoid size are not fully understood. Reported factors include ethnicity, sex, and height. However, many studies have been conducted with relatively younger age groups on the assumption that no significant change in the size of the glenoid fossa occurs after the termination of bone growth. The purpose of this study was to examine glenoid size in a population representing the age groups eligible for rotator cuff surgery and to identify the influence of age on the size of the glenoid. MethodsThis retrospective review included 380 shoulders in 380 patients (151 females and 229 males; mean age: 67.2 ± 10.1 years; range: 27–89 years) who underwent preoperative three-dimensional computed tomography (3D-CT) evaluation and elective shoulder surgery (open or arthroscopic). The exclusion criteria were: history of prior shoulder surgery or glenoid fractures; history of shoulder instability; patients aged younger than 25 years; and those with advanced glenohumeral osteoarthritis. Anatomic parameters of the glenoid (height and width) were measured using 3D-CT images. A generalized linear model with the gamma distribution (multivariate gamma regression) was used in the analysis with the glenoid size (height or width) as the dependent variable. Initial exploratory models included all independent variables, followed by the stepwise selection of variables based on the P value, variance inflation factor, and Akaike’s information criterion for developing the final models. ResultsThe final analytical model showed that age was a significant predictor in both glenoid height and width. The mean glenoid width was 31.2 mm in men and 26.1 mm in women, and the mean glenoid height was 41.1 mm in men and 38.8 mm in women. Other factors that were significant were sex, body height, and hand dominancy. The analysis models accounted for 65% of the glenoid height (pseudo r-squared = 0.65; likelihood ratio test, P = .011) and 73% of the glenoid width (pseudo r-squared = 0.73; likelihood ratio test, P < .0001). ConclusionThis study showed that predictors of glenoid size (height and width) included age. Other positive predictors were shown to be taller body height, male gender, and dominant hand. The influence of rotator cuff tear was not observed.

Does native glenoid anatomy predispose to shoulder instability? An MRI analysis.

It is unclear if native glenohumeral anatomic features predispose young patients to instability and if such anatomic risk factors differ between males and females. The purpose of this study was to compare glenoid and humeral head dimensions between patients with a documented instability event without bone loss to matched controls and to evaluate for sex-based differences across measurements. The authors hypothesized that a smaller glenoid width and glenoid surface area would be significant risk factors for instability, whereas humeral head width would not. A prospectively maintained database was queried for patients aged <21 years who underwent magnetic resonance imaging (MRI) for shoulder instability. Patients with prior shoulder surgery, bony Bankart, or glenoid or humeral bone loss were excluded. Patients were matched by sex and age to control patients who had no history of shoulder instability. Two blinded independent raters measured glenoid height, glenoid width, and humeral head width on sagittal MRI. Glenoid surface area, glenoid index (ratio of glenoid height to width), and glenohumeral mismatch ratio (ratio of humeral head width to glenoid width) were calculated. A total of 107 instability patients and 107 controls were included (150 males and 64 females). Among the entire cohort, there were no differences in glenoid height, glenoid width, glenoid surface area, humeral head width, or glenoid index between patients with instability and controls. Overall, those with instability had a greater glenohumeral mismatch ratio (P=.029) compared with controls. When stratified by sex, female controls and instability patients showed no differences in any of the glenoid or humerus dimensions. However, males with instability had a smaller glenoid width by 3.5% (P=.017), smaller glenoid surface area by 5.2% (P=.015), and a greater glenohumeral mismatch ratio (P=.027) compared with controls. Compared with controls, males with instability were found to have smaller glenoid width and surface area, and a glenoid width that was proportionally smaller relative to humeral width. In contrast, bony glenohumeral morphology did not appear to be a significant risk factor for instability among females. These sex-based differences suggest that anatomic factors may influence risk of instability for male and female patients differently.

Arthroscopic repair of inferior glenoid labrum tears (Down Under lesions) produces similar outcomes to other glenoid tears.

Inferior glenoid labral tears are an uncommon but distinct shoulder injury. Only a small number of studies have reported outcomes following arthroscopic repair. The aim of the current study was to report minimum 2-year outcomes following inferior labral repair and to compare outcomes and risk factors associated with the injury to non-inferior labral tears. Whether preoperative MRI or MRA identified inferior labral tears was also assessed. A prospective study of 162 consecutive patients undergoing arthroscopic glenoid labral repair, excluding isolated superior labral tears, was conducted. Of the 130 patients available for follow-up, 18 (13.7%) had an inferior labral tear ("Down Under lesion"), the remainder had anterior, posterior or mixed anterior/posterior lesions that did not include the inferior pole. Mean follow-up time for theDown Under group was 44months (SD 10, range 27-57), and 30months (SD 14, range 4-60) for the non-Down Under group. Postoperative outcomes included the Oxford Shoulder Instability Score and recurrent instability. Associations between Down Under lesions and injury mechanism, instability at presentation, recurrent instability and family history were assessed with multivariable logistic regression. Preoperative MRI or MRA reports by radiologists were examined to determine if Down Under lesions were identified. Oxford Shoulder Instability Scores indicated that most patients in both groups had little pain or shoulder problems postoperatively (average Oxford Score 41; 48 = no symptoms). Oxford Scores were not significantly different between the Down Under and non-Down Under groups. Four patients (22.2%) in the Down Under group had recurring symptoms (pain and instability) compared to 12 (10.6%) in the non-Down Under group; this difference was not statistically significant (adjusted OR 1.09, 95% CI 0.19,4.77). Family history of shoulder instability was positively associated with a Down Under lesion (adjusted OR 5.0, 95%CI 1.51,16.7). MRI or MRA identified 52.9% of Down Under lesions. Down Under lesions were an infrequent type of glenoid labral injury, yet postoperative outcomes were similar to other labral tears. Patients with Down Under lesions had a significant risk factor due to family history of shoulder instability. MRI and MRA could not reliably identify Down Under lesions. Level III.

Association between shoulder coracoacromial arch morphology and anterior instability of the shoulder

BackgroundGlenohumeral instability is a common condition of the shoulder. Glenoid bone loss and humeral head bone loss are well recognized as risk factors for recurrent instability. There are few studies in the literature that examine the role of coracoacromial arch anatomy in the pathogenesis of glenohumeral instability. Previous reports found an association between posterior acromial coverage (PAC) and posterior instability. We hypothesize that coracoacromial arch anatomy is related to anterior shoulder instability.MethodsIn this retrospective cohort study, 50 patients with unidirectional anterior shoulder instability were matched to a control group of 50 glenohumeral arthritis patients without any history of shoulder instability. Radiographic measurements of the coracoacromial arch anatomy were made: shoulder arch angle, scapular Y angle, anterior coracoid tilt (ACT), posterior acromial tilt, anterior acromial coverage angle, PAC angle, coracoid height, posterior acromial height, and critical shoulder angle were determined using standard lateral scapular and anteroposterior radiographs.ResultsLogistic regression analyses found a significant association between the presence of anterior instability and flatter coracoacromial arch angles (mean, 124.1°) vs. the arthritis control group (mean, 120.6°) (odds ratios [OR] = 1.113; 95% confidence interval [CI] = 1.039-1.191; P = .002). There was a significant association between anterior instability and ACT (OR = 1.144; 95% CI = 1.053-1.243; P = .001), whereas a negative association was found between anterior instability and PAC (OR = 0.909; 95% CI = 0.853-0.969; P = .004) and posterior acromial tilt (OR = 0.878; 95% CI = 0.773-0.998; P = .046). Lower critical shoulder angle values were associated with the arthritis group (28.2° vs. 33.9°) (OR = 1.555; 95% CI = 1.202-2.012; P = .001).ConclusionsShoulder coracoacromial arch morphology may play a role in the stability of the shoulder joint and development of recurrent anterior instability. Shoulders with a decreased shoulder arch angle, a less contained and flatter coracoacromial arch and larger ACT, were associated with anterior instability. This study identifies the shoulder coracoacromial arch angle and anterior coracoid tile angles as risk factors for anterior shoulder instability. Our findings suggest that measuring these angles may help orthopedic surgeons understand the risk of anterior instability and analyze risk factors to improve clinical decision making.

Management of the Failed Latarjet Procedure: Outcomes of Revision Surgery With Fresh Distal Tibial Allograft

Background: Patients with recurrent anterior glenohumeral instability after a failed Latarjet procedure remain a challenge to address. Complications related to this procedure include large amounts of bone loss, bone resorption, and issues with retained hardware that necessitate the need for revision surgery. Purpose: To determine the outcomes of patients who underwent revision surgery for a recurrent shoulder instability after a failed Latarjet procedure with fresh distal tibial allograft. Study Design: Case series; Level of evidence, 4. Methods: All consecutive patients who underwent revision of a failed Latarjet procedure with distal tibial allograft were prospectively enrolled. Patients were included if they had physical examination findings consistent with recurrent anterior shoulder instability. Patients were excluded if they had prior neurologic injury, a seizure disorder, bone graft requirements to the humeral head, or findings of multidirectional or posterior instability. History of shoulder instability was documented, including initial dislocation history, duration of instability, number of prior surgeries, examination findings, plain radiographic and computed tomography (CT) data, and arthritis graded with Samilson and Prieto (SP) classification. All patients were treated with hardware removal, capsular release with subsequent repair, and fresh distal tibial allograft to the glenoid. Outcomes before and after revision were assessed according to the American Shoulder and Elbow Score (ASES), Single Assessment Numerical Evaluation (SANE), and Western Ontario Shoulder Index (WOSI) and statistically compared. All patients underwent a CT scan of the distal tibial allograft at a minimum 4 months after surgery. Results: There were 31 patients enrolled (all males), with a mean age of 25.5 years (range, 19-38 years) and a mean follow-up time of 47 months (range, 36-60 months) after revision with distal tibial allograft. Before distal tibial allograft augmentation, the mean percentage glenoid bone loss was 30.3% (range, 25%-49%). All patients after their Latarjet stabilization had recurrent shoulder dislocation (11/31, 35.5%) or subluxation (20/31, 64.5%), and all patients had symptoms consistent with recurrent shoulder instability upon physical examination. Radiographs demonstrated 2 fixation screws in all cases, mean SP grade was 0.5 (range, 0-3), and CT scans revealed that a mean 78% of the Latarjet coracoid graft had resorbed (range, 37%-100%). Patient-reported outcome scores improved significantly pre- to postoperatively for ASES (40 to 92, P = .001), SANE (44 to 91, P = .001), and WOSI (1300 to 310, P = .001). There were no cases of recurrence, and a final CT scan of the distal tibial revision demonstrated a complete union at the glenoid–distal tibial allograft interface in 92% of patients. Conclusion: The majority of the failed Latarjet procedures included in this study had near-complete resorption of the coracoid graft and hardware complications. At a minimum follow-up time of 36 months, patients who underwent revision treatment for a failed Latarjet procedure with a fresh distal tibial allograft demonstrated excellent clinical outcomes and near-complete osseous union at the glenoid-allograft interface. Although patients evaluated with recurrent anterior shoulder instability after a failed Latarjet procedure remain a challenge to address, fresh distal tibial allograft augmentation is a viable and highly effective revision procedure to treat this patient population.

Management of The Failed Latarjet Procedure: Outcomes of Revision Surgery With Fresh Distal Tibial Allograft

Objectives: A patient with recurrent instability after a failed Latarjet procedure remains a challenge to address. The vast majority of these result in large amounts of bone loss, resorption, and issues with retained hardware, and there is minimal literature that assesses outcomes of revision surgery following a failed Latarjet. The objective of this study was to determine the outcomes of patients who underwent revision surgery for a recurrent shoulder instability after a failed Latarjet procedure. Methods: All consecutive patients who presented with recurrent anterior shoulder instability after a Latarjet procedure were prospectively enrolled. Patients were included if they had a prior Latarjet, and a history and physical examination findings consistent with recurrent anterior shoulder instability. Patients were excluded if they had prior neurologic injury, a seizure disorder, bone graft requirements to the humeral head, or findings of multidirectional or posterior instability. History of shoulder instability was documented, including initial dislocation history, time of instability, number of prior procedures, and examination findings, as well as plain radiographic data and computed tomography (CT) scan obtained on all patients, and arthritis graded with Samilson and Prieto (SP) grade. All patients were treated with hardware removal, capsulo-labral release with subsequent repair and bony reconstruction via fresh distal tibial allograft to the glenoid. Outcomes pre- and post-revision were assessed with ASES (American Shoulder and Elbow Score), Single Assessment Numerical Evaluation (SANE), and Western Ontario Shoulder Index (WOSI), and statistically compared. All patients underwent a CT scan of the distal tibial allograft at a minimum time point 4 months after surgery. Results: There were 31 patients enrolled (all males), with mean age 25.5 (range, 19 to 38), and with a mean follow-up of 47 months (range, 36 to 60) after the revision with distal tibial allograft. All patients after their Latarjet presented with recurrent shoulder dislocation (11/31) or recurrent subluxation (20/31) and all patients had recurrent shoulder instability on examination. Radiographs demonstrated two fixation screws in all cases, mean SP grade of 0.5 (range, I to III), and CT scan demonstrated that mean 78% of the Latarjet coracoid graft had resorbed (range, 50% to 100%). Preoperative outcomes improved for ASES (40 to 92, p=0.001), SANE (44 to 91, p=0.001), and WOSI (1300 to 310, p=0.001). There were no recurrences, and a final CT scan of the distal tibia revision demonstrated a mean 92% of DTA remained, but 98% union at the glenoid-DTA interface. Conclusion: Although the failed Latarjet with subsequent instability remains a challenge, treatment with fresh a distal tibial allograft provided substantial improvement in terms of stability and function. The vast majority of the failed Latarjet procedures had near complete resorption of the coracoid graft and many had hardware complications. Additional long-term studies are necessary to determine the efficacy of this challenging revision population.

Increased Glenoid Retroversion Is Associated With Increased Rotator Cuff Strength in the Shoulder

Background: The rotator cuff muscles are critical secondary stabilizers in the shoulder. Increased glenoid retroversion and rotator cuff strength have been associated with the risk of posterior shoulder instability; however, the effect of increased glenoid retroversion on rotator cuff strength remains unclear. Purpose/Hypothesis: The purpose was to examine the association between glenoid version and rotator cuff strength in the shoulder in a young and healthy population with no history of shoulder instability. The hypothesis was that increased glenoid retroversion would be associated with increases in rotator cuff muscle strength. Study Design: Cross-sectional study; Level of evidence, 3. Methods: A prospective cohort study was conducted over a 4-year period within a high-risk population to identify the risk factors for shoulder instability. Analyzed participants included 574 freshmen entering a United States service academy. Baseline data collected upon entry into the study included magnetic resonance imaging measurements of glenoid version. Rotator cuff strength was also assessed at baseline using a handheld dynamometer. Internal and external rotation strength were assessed with the glenohumeral joint positioned in neutral and in 45° of abduction. The current study represents an analysis of the baseline data from this cohort. Results: The mean age, height, and weight of participants was 18.77 ± 0.97 years, 176.81 ± 8.48 cm, and 73.80 ± 12.45 kg, respectively. The mean glenoid version at baseline was 7.79°± 4.85° of retroversion. Univariate linear regression analyses demonstrated that increased glenoid retroversion was associated with increased internal and external rotation strength of the rotator cuff in neutral and 45° of abduction (P < .001). Similar results were observed in multivariable models controlling for important confounding variables. Conclusion: The results of this study demonstrate that as glenoid retroversion increases, internal and external rotation strength of the rotator cuff also increase in a young and healthy athletic population. These compensatory changes may contribute to increased glenohumeral dynamic stability in the presence of worse static stability with increasing retroversion.

The pattern of idiopathic isolated teres minor atrophy with regard to its two-bundle anatomy.

We aimed to analyze the pattern of teres minor atrophy with regard to its two-bundle anatomy and to assess its association with clinical factors. Shoulder MRIs performed between January and December 2016 were retrospectively reviewed. Images were evaluated for the presence and pattern of isolated teres minor atrophy. Isolated teres minor atrophy was categorized into complete or partial pattern, and partial pattern was further classified according to the portion of the muscle that was predominantly affected. The medical records were reviewed to identify clinical factors associated with teres minor atrophy. Seventy-eight shoulders out of 1,264 (6.2%) showed isolated teres minor atrophy; complete pattern in 41.0%, and partial pattern in 59.0%. Most cases of partial pattern had predominant involvement of the medial-dorsal component (82.6%). There was no significant association between teres minor atrophy and previous trauma, shoulder instability, osteoarthritis, and previous operation. The history of shoulder instability was more frequently found in patients with isolated teres minor atrophy (6.4%), compared with the control group (2.6%), although the difference was not statistically significant. Isolated teres minor atrophy may be either complete or partial, and the partial pattern may involve either the medial-dorsal or the lateral-ventral component of the muscle. The imaging findings of partial pattern teres minor atrophy indicate that the two muscle components may have separate innervation.

A History of Shoulder Instability in the Military: Where We Have Been and What We Have Learned.

Shoulder instability is one of the most common pathologies seen by the orthopedic sports medicine surgeon. With a uniquely young, high-demand patient population in the U.S. Military, the incidence of shoulder instability is remarkably more common than the civilian population. As such, military orthopedic surgeons and sports medicine and shoulder specialists have developed a unique understanding and experience of shoulder instability. The historical advances of shoulder instability in the military have been instrumental in understanding the epidemiology, evaluation, pathology, treatment of first-time shoulder subluxations and dislocations, operative and non-operative treatment options, arthroscopic and open stabilization methods, management of the in-season athlete, treatment of combined and circumferential labral pathology, and associated pathology. The purpose of this article is to chronicle the experience of military orthopedic surgeons in treating shoulder instability. We discuss how this unique experience has led to a better understanding of the epidemiology and pathology of this condition and how we have adapted our clinical practice to improve patient outcomes. The historical contribution of U.S. Military orthopedics to the understanding of shoulder instability has been monumental. This article reviews the evolution of shoulder instability treatment and the understanding as it has evolved in the U.S. Military. It further elaborates on our understanding of the epidemiology of shoulder instability in the U.S. Military, with attention given to our incidence of 1.69 per 1000 person-years, approximately 20 times higher incidence than the general population. We discuss known risk factors for dislocation that contribute to this incidence, which are specific to military service. We address pathologic changes seen following a first-time instability event, including an analysis of labral injury and the role of these pathologic changes in recurrent instability. We also review our results from arthroscopic evaluation of first-time dislocations and compare the pathologic changes with those following a first-time subluxation. Evaluation of treatment outcomes is discussed, comparing operative and non-operative results as well as open and arthroscopic stabilization in the U.S. Military population and contact/collision athletes. Finally, we address how these results drive our current treatment algorithm. The physical demands of military service result in a high rate of shoulder instability relative to the general population. For years military orthopedic surgeons have sought to better understand this pathology and learn how to optimally manage it so as to reduce this heavy burden of disease. This article discusses our experience with treating shoulder instability, provides an overview of the lessons learned, and provides a historical perspective for the evolution of shoulder instability understanding in the U.S. Military.

The Effect of Shoulder Muscle Fatigue on Acromiohumeral Distance and Scapular Dyskinesis in Women With Generalized Joint Hypermobility.

Muscle fatigue is considered to be one cause of shoulder pain, and subjects with generalized joint hypermobility (GJH) are affected more by shoulder pain. The purpose of this study was to examine the effects of muscle fatigue on acromiohumeral distance (AHD) and scapular dyskinesis in women with GJH. Thirty-six asymptomatic participants were assigned to either a GJH (n = 20) or control group (n = 16) using the Beighton scale. Before and after elevation fatigue trials, AHD was measured with ultrasonography at rest and when the arm was in 90° active elevation. A scapular dyskinesis test was used to visually observe alterations in scapular movement. Our results showed that in both groups, the fatigue reduced AHD in the 90° elevation position and increased the presence of scapular dyskinesis; however, no differences were found between the two groups. Although GJH has been identified as a factor for developing musculoskeletal disorders, generalized joint hypermobility did not result in changes to scapular dyskinesis or AHD, even after an elevation fatigue task. More studies are needed to evaluate the effects of muscle fatigue in subjects with GJH and a history of shoulder instability.

History of Shoulder Instability and Subsequent Injury During Four Years of Follow-up

Little is known about the risk factors for glenohumeral joint instability. We hypothesized that a prior history of instability would be a significant risk factor for subsequent injury. We conducted a prospective cohort study over a four-year period within a high-risk group of young athletes to address the research hypothesis. Subjects were freshmen entering the U.S. Military Academy in June of 2006. Part of the baseline assessment included documenting a prior history of glenohumeral instability on entry into the study. All subjects were followed for subsequent glenohumeral joint instability events until graduation in May of 2010. The primary outcome of interest in this study was time to glenohumeral instability event during the follow-up period. We examined injury outcomes, looking for any instability, anterior instability, and posterior instability events. Cox proportional-hazards regression models were used to analyze the data. Among the 714 subjects, eight shoulders were excluded from the analyses due to prior surgical stabilization, leaving 1420 shoulders, of which 126 had a self-reported prior history of instability. There were forty-six (thirty-nine anterior and seven posterior) acute instability events documented in the cohort during the follow-up period. Subjects with a prior history of instability were over five times (p < 0.001) more likely to sustain an acute (anterior or posterior) instability event during the follow-up period. Subjects with a history of instability were also 5.6 times (p < 0.001) more likely to experience a subsequent anterior instability event and 4.6 times (p = 0.068) more likely to experience a posterior instability event during follow-up. Similar results were observed in multivariable models after controlling for the influence of demographic and baseline physical examination findings. Despite meeting the rigorous physical induction standards for military service, subjects with a prior history of glenohumeral joint instability were approximately five times more likely to experience a subsequent instability event, regardless of direction, within this high-risk athletic population.

Simple Method of Glenoid Bone Loss Calculation Using Ipsilateral Magnetic Resonance Imaging

Background: Current methods for estimating glenoid bone loss in patients with chronic shoulder instability include computed tomography imaging with 3-dimensional reconstruction, specialized computer software, and imaging of the contralateral shoulder. An ideal method of glenoid measurement would require only magnetic resonance imaging (MRI) of the injured shoulder. Purpose: To determine whether MRI measurement of glenoid height, as well as sex, could be used to estimate glenoid width in healthy subjects with no history of shoulder instability. Study Design: Cross-sectional study; Level of evidence, 3. Methods: Bilateral shoulder MRIs were obtained in a healthy cohort of young athletes as part of the baseline assessment in a prospective cohort study. A musculoskeletal radiologist measured glenoid height and width using the sagittal MRI cuts. Univariate and multivariate regression analyses were performed to determine whether demographic and MRI measurements of the glenoid could be used to estimate glenoid width. Results: Of the 1264 shoulder MRIs evaluated, the mean glenoid width was 26.67 mm (±2.49 mm), and the mean glenoid height was 42.15 mm (±3.00 mm). There were significant differences between the 129 female glenoids and the 1035 male glenoids for both width (23.1 mm, 27.1 mm, respectively, P < .0001) and height (37.9 mm, 42.7 mm, respectively, P < .0001); however, the relationship between glenoid height and width was similar for both men and women. The glenoid width was found to correlate with the height measurement (r = 0.56) for the entire cohort. Based on the results of linear regression analysis, controlling for the influence of sex, a formula was created that represents the relationship between these variables for male subjects: Glenoid Width = (1/3 Height) + 15 mm. Female patients are estimated with a formula that represents the same slope but a different intercept: W = 1/3 H + 13 mm. Conclusion: Significant differences in glenoid height and width were found by sex; however, the relationship between height and width was similar. These variables are correlated, and the resultant formula can be used to estimate the expected glenoid width in a patient with bone loss. This formula allows for easy calculation of the amount of glenoid bone loss with only a ruler and an MRI of the injured shoulder.

Physical Examination Findings in Young Athletes Correlate with History of Shoulder Instability

The goal of this study was to evaluate physical examination findings in a healthy cohort and determine potential correlations with a history of shoulder instability. A cross-sectional analysis was performed using the baseline data for an ongoing prospective cohort study to examine the risk factors for shoulder instability. A complete history of shoulder instability events was obtained, and a blinded physical examination was performed. The cohort comprised 711 patients (627 men, 84 women) with a mean age of 18.8 years. A total of 100 patients had a history of shoulder instability. Patients with a history of instability were more likely to have increased posterior translation (P=.010), positive apprehension sign (P=.003), positive relocation sign (P=.007), and sulcus sign (P=.017).

Shoulder laxity and traumatic shoulder instability in professional rugby players

ObjectiveThis study aimed to see whether the risk of shoulder dislocation is associated with innate shoulder laxity, in professional rugby players.MethodologyWe performed a pilot study where we validated techniques we...

Management of Shoulder Instability in In-Season Athletes

Although shoulder instability is common in young athletes, there are limited prospective data to guide treatment for competitive athletes who sustain a dislocation mid-season. The management of athletes during their competitive season requires an understanding of the natural history of shoulder instability, the specific needs of the injured athlete (eg, specific sport, player position), and the duration of treatment. Rehabilitation can enable an athlete with a shoulder dislocation to return to play within 3 weeks of injury. Bracing is an option, but it can result in restricted glenohumeral motion and thereby possibly affect performance. Surgical stabilization should be considered for the athlete with recurrent instability or inability to perform; however, this frequently results in the termination of the player's season. In this article, we review the available literature to help guide physicians treating athletes with shoulder instability.

Shoulder proprioception in baseball pitchers

We examined proprioceptive differences between the dominant and nondominant shoulders of 21 collegiate baseball pitchers without a history of shoulder instability or surgery. A proprioceptive testing device was used to measure kinesthesia and joint position sense. Joint position sense was significantly (P =.05) more accurate in the nondominant shoulder than in the dominant shoulder when starting at 75% of maximal external rotation and moving into internal rotation. There were no significant differences for proprioception in the other measured positions or with kinesthesia testing. Six pitchers with recent shoulder pain had a significant (P =.04) kinesthetic deficit in the symptomatic dominant shoulder compared with the asymptomatic shoulder, as measured in neutral rotation moving into internal rotation. The net effect of training, exercise-induced laxity, and increased external rotation in baseball pitchers does not affect proprioception, although shoulder pain, possibly due to rotator cuff inflammation or tendinitis, is associated with reduced kinesthetic sensation. (J Shoulder Elbow Surg 2001;10:438-44.)

Glenohumeral ligaments and shoulder capsular mechanism: evaluation with MR arthrography.

To evaluate the efficacy of magnetic resonance (MR) arthrography in identification of the glenohumeral ligaments (GHLs) and to determine the location of abnormalities of the GHL, joint capsule, and labrum. MR arthrograms were evaluated retrospectively in 46 patients with a history of shoulder instability, impingement syndrome, or pain of unknown cause. Imaging findings were correlated with surgical observations. The superior, middle, and inferior GHLs were identified on MR arthrograms in 39 (85%), 39 (85%), and 42 (91%) of the 46 patients, respectively. In diagnosis of tears of the superior, middle, and inferior GHLs, MR arthrography had a sensitivity of 100%, 89%, and 88% and a specificity of 94%, 88%, and 100%, respectively. Findings at MR arthrography can help accurate identification and demonstration of the integrity of the GHL and labrum and can help in staging of abnormalities. The large number of abnormalities depicted in the middle and inferior GHLs suggests that both might be important in the maintenance of glenohumeral joint congruity.