On-Track Lesions with a Small Distance to Dislocation Are Associated with Failure After Arthroscopic Anterior Shoulder Stabilization

Accuracy and reliability of imaging modalities for studying bipolar bone loss in anterior shoulder instability: A systematic review

PURPOSE

Recurrent shoulder instability, a common musculoskeletal disorder, often involves glenoid bone loss and Hill-Sachs lesions. However, the optimal imaging modality for accurately and reliably quantifying bipolar bone loss remains uncertain. This systematic review aims to evaluate the accuracy and reliability of various imaging modalities in assessing bipolar bone loss in anterior shoulder instability.

METHODS

Major electronic databases were searched for English-language studies reporting the measurement of glenoid track width and/or determination of on/off track HSL through imaging. Studies reporting statistical measures such as area under the curve, sensitivity, specificity, positive predictive value, NPV, intraobserver reliability and interobserver reliability were included. Data extraction and risk of bias assessment were performed independently by two reviewers.

RESULTS

The systematic review included 19 studies comprising 1567 shoulders. Overall, studies could be divided into those looking at the accuracy or reliability of determining glenoid track width, on- or off-track Hill-Sachs lesions and near-track lesions. Three-dimensional images of computed tomography (3D-CT) was the most reliable and accurate imaging modality to measure the glenoid track width. On the opposite, two-dimensional magnetic resonance imaging (2D-MRI) did not provide enough evidence of accuracy and reliability in the determination of On/Off track lesions and near-track lesions.

CONCLUSION

3D-CT demonstrated excellent reliability for measuring glenoid track width. However, the reliability of 2D-MRI for determining on/off track Hill-Sachs lesions is still controversial.

LEVEL OF EVIDENCE

Level III.

An Evidence-Based Approach to Indication for Remplissage

PURPOSE OF REVIEW

Treatment of anterior shoulder instability (ASI) is complex with many factors contributing to surgical decision making. The remplissage is an adjunct surgical technique that can be added at the time of arthroscopic labral repair or glenoid bone block reconstruction to decrease the recurrence rate of ASI post-operatively. The purpose of this review is to highlight the history, indications, and outcomes of remplissage when used for anterior shoulder instability.

RECENT FINDINGS

Prior studies have demonstrated that remplissage, when used in addition to an arthroscopic labral repair, can significantly reduce the rate of recurrent instability in patients with both off-track and near-track Hill Sachs lesions. There remains concern that addition of remplissage will negatively affect post-operative range of motion (ROM). However, recent literature suggests no difference observed in ROM when comparing remplissage plus arthroscopic labral repair to arthroscopic labral repair alone. While the addition of a remplissage has promising rates of return to sport, these results are less favorable when a remplissage is performed in an overhead athlete. The remplissage is a powerful surgical tool to utilize in addition to an arthroscopic labral repair or glenoid bone block reconstruction in patients with anterior instability. An understanding of appropriate indications and its influence on post-operative outcomes can assist the surgeon with providing the best possible outcome for each individual patient.

Minimizing Risk of Recurrent Instability Following Surgical Stabilization for Anterior Glenohumeral Instability

The most common surgical treatment options for anterior shoulder instability include the arthroscopic Bankart repair with or without adjunct procedures such as remplissage, the open Bankart repair, the Bristow-Latarjet procedure, and anterior free bone block transfers. The choice between non-operative treatment and 1 of the aforementioned procedures inherently impact the risk of recurrent instability. The purpose of this article is to discuss the timing of surgery in the in-season athlete, evaluate the evolving concept of glenoid and bipolar bone loss, and to discuss various surgical treatment options with a specific focus on minimizing recurrent instability rates following surgical stabilization.

Lower Range of Recurrent Instability Rates Following Bankart Repair and Remplissage Compared to Isolated Bankart Repair in Patients With "Nonengaging/On-Track" Hill-Sachs Lesions and <20% Glenoid Bone Loss

PURPOSE

To compare recurrent instability and return-to-sport rates along with external rotation differences between on-track (nonengaging) Hill-Sachs lesion patients undergoing either an isolated Bankart repair (IBR) or a Bankart repair augmented with a remplissage procedure (B+R).

METHODS

A search was conducted using 3 databases (PubMed, EMBASE, CINAHL) in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Only clinical comparative (level of evidence I-III) studies were considered for inclusion. Quality assessment was performed using the Methodological Index for Non-Randomized Studies criteria.

RESULTS

Six level of evidence III studies, totaling 537 patients (202 B+R and 335 IBR) were included for analysis. All patients had <20% glenoid bone loss and a nonengaging, on-track Hill-Sachs lesion. At a median final follow-up of 34.7 months, recurrent dislocation rates ranged from 0% to 7.7% and 3.5% to 30% in the B+R and IBR groups, respectively. Moreover, subjective instability and revision surgery rates presented lower ranges in the B+R upon comparison with the IBR cohort (0%-32% vs 5%-71.4% and 0%-5% vs 0%-35%, respectively). Furthermore, return to preinjury level of sports ranged from 64% to 100% in the remplissage-augmented group and 50% to 90% in the IBR cohort. Postoperative external rotation at side varied from 50° to 63° in the B+R and 55° to 63° in the IBR arm. Additional subgroup analysis revealed recurrent dislocation rates in athletes and patients with near-track Hill-Sachs lesions undergoing remplissage augmentation to be 0% to 5% and 2% to 47% while ranging from 8.8% to 30% and 9% to 66% for IBR patients, respectively.

CONCLUSIONS

Upon qualitative analysis, ranges of recurrent instability measures, including recurrent dislocation rates, are higher in patients undergoing IBR in comparison to B+R. Activity level influences outcomes as athletes were found to have a higher range of recurrent dislocation rates in the IBR group. The addition of remplissage showed a higher range of return-to-sport rates with comparable postoperative external rotation between groups.

LEVEL OF EVIDENCE

Level III, systematic review of Level III studies.

Methodology and development of a machine learning probability calculator: Data heterogeneity limits ability to predict recurrence after arthroscopic Bankart repair

PURPOSE

The aim of this study was to develop and train a machine learning (ML) algorithm to create a clinical decision support tool (i.e., ML-driven probability calculator) to be used in clinical practice to estimate recurrence rates following an arthroscopic Bankart repair (ABR).

METHODS

Data from 14 previously published studies were collected. Inclusion criteria were (1) patients treated with ABR without remplissage for traumatic anterior shoulder instability and (2) a minimum of 2 years follow-up. Risk factors associated with recurrence were identified using bivariate logistic regression analysis. Subsequently, four ML algorithms were developed and internally validated. The predictive performance was assessed using discrimination, calibration and the Brier score.

RESULTS

In total, 5591 patients underwent ABR with a recurrence rate of 15.4% (n = 862). Age <35 years, participation in contact and collision sports, bony Bankart lesions and full-thickness rotator cuff tears increased the risk of recurrence (all p < 0.05). A single shoulder dislocation (compared to multiple dislocations) lowered the risk of recurrence (p < 0.05). Due to the unavailability of certain variables in some patients, a portion of the patient data had to be excluded before pooling the data set to create the algorithm. A total of 797 patients were included providing information on risk factors associated with recurrence. The discrimination (area under the receiver operating curve) ranged between 0.54 and 0.57 for prediction of recurrence.

CONCLUSION

ML was not able to predict the recurrence following ABR with the current available predictors. Despite a global coordinated effort, the heterogeneity of clinical data limited the predictive capabilities of the algorithm, emphasizing the need for standardized data collection methods in future studies.

LEVEL OF EVIDENCE

Level IV, retrospective cohort study.

Glenoid Labral Articular Disruption Lesions in the Setting of First-Time Anterior Shoulder Instability

PURPOSE

To compare the clinical outcomes and rates of recurrent instability in patients after arthroscopic Bankart repair with and without glenolabral articular disruption (GLAD) lesions in the setting of first-time anterior instability events.

METHODS

This was a retrospective comparative case series of consecutive patients with GLAD lesions in the setting of first-time anterior instability events who underwent arthroscopic Bankart repair. Patients with GLAD lesions (cases) were matched at a 1:3 ratio for sex, age, body mass index, and sports participation to those without GLAD lesions (controls). Primary outcomes included postoperative range of motion (forward elevation and external rotation) and patient-reported outcomes: Subjective Shoulder Value, visual analog scale score, and Western Ontario Shoulder Instability Index. Rates of recurrent instability after primary arthroscopic stabilization were also collected. Statistical analysis was performed to compare outcomes between the control and GLAD groups, with significance set to P ≤ 0.05.

RESULTS

A total of 56 patients undergoing arthroscopic anterior stabilization between 2012 and 2020 were included for analysis, of whom 14 had GLAD lesions whereas the remaining 42 were controls. The average follow-up time from surgery in controls was 8.2 years (range, 3.1-11.7 years), whereas the average follow-up time in patients with GLAD lesions was 7.6 years (range, 3.8-11.8 years). There were no differences in postoperative forward flexion or external rotation, Subjective Shoulder Value, visual analog scale score, or Western Ontario Shoulder Instability Index. The rate of recurrent instability was found to be the same in both the control and GLAD groups (7% and 7%, respectively; P = .16).

CONCLUSIONS

Patients with GLAD lesions in the setting of first-time anterior instability had comparable patient-reported outcomes, forward flexion, and external rotation postoperatively to control patients. In addition, the presence of a GLAD lesion did not influence the rate of recurrent instability.

LEVEL OF EVIDENCE

Level IV, retrospective comparative case series.

Editorial Commentary: Open Bankart Procedure for Anterior Shoulder Instability Is Recommended for Contact Athletes With Bony Bankart Fractures or Approximately 10% Glenoid Bone Loss

Recurrent anterior shoulder instability with subcritical bone loss is a challenging clinical scenario. Many treatment options have been described, including arthroscopic Bankart repair, arthroscopic Bankart repair plus remplissage, open Bankart repair, and the Latarjet procedure. Arthroscopic Bankart repair alone has higher rates of failure in high-risk patient populations, especially at long-term follow-up. These high-risk populations include patients with significant glenoid bone loss (>20%), bipolar bone loss (including subcritical bone loss and off-track or "near-track" [8-10 mm] Hill-Sachs lesions), and demographic risk factors including young age, hyperlaxity, contact sports participation, and number of prior dislocations. Treatment algorithms favor arthroscopic Bankart repair plus remplissage or the Latarjet procedure for high-risk patients, but they go from "A" (arthroscopy) to "C" (coracoid transfer) and forget about "B" (open Bankart repair). Open Bankart repair has decreased in use by 65% across the United States since 2008, whereas the popularity of the Latarjet procedure has risen by 250% over the same time frame. With its reported success at long-term follow-up (1.6%-17.5% failure rates at 17-21 years), open Bankart repair must be reconsidered for properly indicated patients. Ongoing large-scale multicenter trials such as the Open Versus Arthroscopic Surgery for Shoulder Instability (OASIS) trial are looking at arthroscopic Bankart repair with or without remplissage versus open Bankart repair versus the Latarjet procedure in the setting of 10% to 20% anterior glenoid bone loss. We highly recommend open Bankart repair in contact athletes with an acute bony Bankart fracture and thoughtfully consider open Bankart repair in contact athletes with approximately 10% glenoid bone loss.

Anterior Glenohumeral Instability: Clinical Anatomy, Clinical Evaluation, Imaging, Nonoperative and Operative Management, and Postoperative Rehabilitation

➢ Anterior glenohumeral instability is a complex orthopaedic problem that requires a detailed history, a thorough physical examination, and a meticulous review of advanced imaging in order to make individualized treatment decisions and optimize patient outcomes.➢ Nonoperative management of primary instability events can be considered in low-demand patients, including elderly individuals or younger, recreational athletes not participating in high-risk activities, and select in-season athletes. Recurrence can result in increased severity of soft-tissue and osseous damage, further increasing the complexity of subsequent surgical management.➢ Surgical stabilization following primary anterior instability is recommended in young athletes who have additional risk factors for failure, including participation in high-risk sports, hyperlaxity, and presence of bipolar bone loss, defined as the presence of both glenoid (anteroinferior glenoid) and humeral head (Hill-Sachs deformity) bone loss.➢ Several surgical treatment options exist, including arthroscopic Bankart repair with or without additional procedures such as remplissage, open Bankart repair, and osseous restoration procedures, including the Latarjet procedure.➢ Favorable results can be expected following arthroscopic Bankart repair with minimal (<13.5%) bone loss and on-track Hill-Sachs lesions following a primary instability event. However, adjunct procedures such as remplissage should be performed for off-track lesions and should be considered in the setting of subcritical glenoid bone loss, select high-risk patients, and near-track lesions.➢ Bone-grafting of anterior glenoid defects, including autograft and allograft options, should be considered in cases with >20% glenoid bone loss.

Mid- to Long-Term Clinical Outcomes and Failure Rates After ALPSA Lesion Repair

BACKGROUND

Anterior labroligamentous periosteal sleeve avulsion (ALPSA) lesions are associated with recurrent shoulder instability and higher rates of failure after capsulolabral repair compared with similarly treated Bankart lesions. Although these lesions can portend poor outcomes, there are limited data on the associated conditions and postoperative course in a young, active population.

PURPOSE

To evaluate the mid- to long-term clinical course and failure rates after ALPSA repairs and assess features associated with these outcomes.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

The authors identified all patients who underwent primary arthroscopic anterior or combined anterior and posterior labral repair between January 2010 and January 2020 at a single US military academy. Patient and injury characteristics were retrospectively reviewed while excluding patients with follow-up of <2 years. Patients were divided into 2 cohorts based on the presence of an ALPSA lesion as identified using arthroscopy, and patients with non-ALPSA lesions were matched to those with ALPSA lesions in a 5:1 ratio based on age, sex, time from injury to surgery, glenoid bone loss, and follow-up duration. The primary outcome measures were failure and revision surgery. Any recurrent shoulder instability event was considered a failure, including subjective or objective subluxation and/or dislocation, recurrence of pain consistent with instability, or functionally limiting apprehension. Survival analysis and both univariate and multivariate logistic regression analyses were performed to identify factors associated with ALPSA lesions and propensity for failure.

RESULTS

The authors compared 225 patients with non-ALPSA labral tears against 45 patients with ALPSA lesions. ALPSA lesions were associated with multiple preoperative dislocations (odds ratio [OR], 3.0; 95% CI, 1.5-5.9; P = .00096) and increased prevalence of Hill-Sachs lesions (HSLs) (OR, 6.7; 95% CI, 2.8-16.0; P < .0001) and near-track HSLs (OR, 3.6; 95% CI, 1.7-7.6; P = .00049). At the final follow-up, there was no difference in overall failure or recurrent instability between patients with and without ALPSA lesions (20% vs 16% [P = .563] and 17.8% vs 10.2% [P = .147], respectively). On multivariate regression, ALPSA did not affect the likelihood of failure (P = .625). However, those with ALPSA lesions experienced failure earlier (1.7 vs 3.1 years; P = .020). When revision ALPSA repairs were performed, 43% failed.

CONCLUSION

In patients with anterior instability treated with primary arthroscopic stabilization, ALPSA lesions were associated with HSLs and multiple dislocations. Although ALPSA repair failure occurred at a similar frequency in the mid- to long term compared with Bankart repairs, ALPSA repair failure tended to occur early in the postoperative course.

Arthroscopic Bankart repair with remplissage yields similar outcomes to open Latarjet for primary and revision stabilization in the setting of subcritical glenoid bone loss

BACKGROUND

Management of patients with recurrent anterior glenohumeral instability in the setting of subcritical glenoid bone loss (GBL), defined in this study as 20% GBL or less, remains controversial. This study aimed to compare arthroscopic Bankart with remplissage (ABR + R) to open Latarjet for subcritical GBL in primary or revision procedures. We hypothesized that ABR + R would yield higher rates of recurrent instability and reoperation compared to Latarjet in both primary and revision settings.

METHODS

A retrospective study was conducted on patients undergoing either arthroscopic ABR + R or an open Latarjet procedure. Patients with connective tissue disorders, critical GBL (>20%), <2 year follow-up, or insufficient data were excluded. Recurrent instability and revision were the primary outcomes of interest. Additional outcomes of interest included subjective shoulder value, strength, and range of motion (ROM) RESULTS: One hundred eight patients (70 ABR + R, 38 Latarjet) were included with an average follow-up of 4.3 ± 2.1 years. In the primary and revision settings, similar rates of recurrent instability (Primary: P = .60; Revision: P = .28) and reoperation (Primary: P = .06; Revision: P = 1.00) were observed between Latarjet and ABR + R. Primary ABR + R exhibited better subjective shoulder value, active ROM, and internal rotation strength compared to primary open Latarjet. However, no differences were observed in the revision setting.

CONCLUSION

Similar rates of recurrent instability and reoperation in addition to comparable outcomes with no differences in ROM were found for ABR + R and Latarjet in patients with subcritical GBL in both the primary and revision settings. ABR + R can be a safe and effective procedure in appropriately selected patients with less than 20% GBL for both primary and revision stabilization.

Comparison of Revision and Redislocation Rates After First-Time Anterior Shoulder Instability Between Subluxators and Dislocators: A Midterm Outcome Study

Background

Anterior shoulder instability is a common pathology seen especially in young men and highly active patient populations. Subluxation is a commonly encountered clinical issue, yet little is known about the effects of first-time subluxation compared with dislocation on shoulder stability and clinical outcomes after surgical stabilization.

Purpose

To compare revision and redislocation rates as well as patient-reported outcomes (PROs) between subluxators and dislocators after a first-time anterior shoulder instability event.

Study Design

Cohort study; Level of evidence, 3.

Methods

Included were patients who underwent operative intervention for a first-time anterior instability event between 2013 and 2020 at a single institution. Exclusion criteria were posterior/multidirectional instability, revision surgery, and recurrent instability. The main outcomes of interest were the rates of redislocation and revision. Demographics and surgical details were retrospectively collected. Instability was categorized as subluxation (no documentation of formal shoulder reduction) or dislocation (documented formal shoulder reduction). Labral tear location and size were determined from preoperative magnetic resonance imaging scans. PROs and return-to-sport, redislocation, and revision rates were collected from prospective survey data.

Results

A total of 256 patients (141 subluxators and 115 dislocators) were available for analysis. There were no significant differences in baseline demographics or preoperative physical examination findings. Rates of bony Bankart lesions were comparable, but Hill-Sachs lesions were more commonly present in dislocators compared with subluxators (88.7% vs 53.9%; P < .01). There were no group differences in labral tear size, incidence of concomitant posterior or superior labrum anterior-posterior tears, or number of anchors used. Rates of remplissage were comparable between groups. Prospectively collected survey data of 60 patients (35 subluxators, 25 dislocators) were collected at 6.4 and 7.1 years of follow-up, respectively. Rates of recurrent dislocation (11.8% vs 20.0%) and revision (8.8% vs 16.0%) were comparable between subluxators and dislocators, respectively. All PROs and return-to-sport rates were comparable between groups.

Conclusion

Subluxators and dislocators may present with comparable rates of redislocation and revision surgery even at midterm follow-up. Both cohorts may further present with comparable injury characteristics and PROs. Given the findings, future prospective studies comparing outcomes of first-time instability events are needed.

Glenoid track revisited

The risk of Hill-Sachs lesion (HSL) to cause instability depends not only on the HSL but also on the glenoid size. Clinically, the only method to assess the risk of instability considering the dynamic interaction of both, the HSL together with the glenoid bone loss, is the glenoid track concept. Since it was introduced in a cadaveric study, its clinical efficacy and validity have been reported in the literature. Sometimes, the medial margin of the footprint (lateral margin of the glenoid track) is difficult to identify when a HSL is overriding the footprint. In such cases, we propose a method to draw an imaginary line connecting 2 landmarks. Although 3-dimensional computed tomography is the most accurate and widely used method to assess on/off-track lesions, our interest gradually is shifting toward magnetic resonance imaging (MRI), which has no radiation concern. The current magnetic resonance method is still under way. There are various risk factors influencing the recurrent instability after surgery. The glenoid track concept deals with only 1 of these factors, that is, instability caused by bony lesions. Therefore, the following 2 issues are important: 1) how to assess the glenoid track precisely and 2) how to incorporate other risk factors into consideration. The former can be achieved by obtaining the custom-made glenoid track width using not the fixed value of 83%, but more individualized value obtained by measuring the active horizontal extension angle of the opposite shoulder in the sitting position. At the same time, the gray zone (peripheral-track lesion) needs to be clearly defined. The latter can be achieved by incorporating the risk factors other than the bony lesions. One example is the Glenoid Track Instability Management Score (GTIMS), a combination of the glenoid track concept and the instability severity index score. This new scoring system is expected to increase the predictive potential of the scoring system, and accordingly to enhance clinical decision-making.

Arthroscopic Bone Block Stabilization for Anterior Shoulder Instability with Subcritical Glenohumeral Bone Loss

PURPOSE OF REVIEW

The management options for anterior shoulder instability with minimal bone loss or with critical bone loss are well established. However, there is less clear evidence to guide management for patients with subcritical bone loss, the spectrum of pathology where soft tissue repair alone is prone to higher rates of failures. In this range of bone loss, likely around 13.5% to 20%, the goal of surgery is to restore function and stability while limiting morbidity. As with many procedures in the shoulder, this decision should be tailored to patient anatomy, functional goals, and risk factors. This article provides a review of our current understanding of subcritical bone loss and treatment strategies as well as innovations in management.

RECENT FINDINGS

While surgeons have largely understood that restoration of anatomy is important to optimize outcomes after stabilization surgery, there is increasing evidence that reconstructing bony anatomy and addressing both osseous and soft tissue structures yields better results than either alone. Even in the setting of subcritical bone loss, there is likely a benefit to combined osseous augmentation with soft tissue management. Additionally, there is new evidence to support management of even on-track humeral lesions when the distance to dislocation is sufficiently small, particularly for athletes. Surgeons must balance bony and soft tissue restoration to achieve optimal outcomes for anterior instability with subcritical bone loss. There are still significant limitations in the literature and several emerging techniques for management will require further study to prove their long-term efficacy. Beyond surgery, there should be a focus on a collaborative treatment strategy with the surgeon, patient, and therapists to achieve high-level function and minimize recurrence.

Extremity War Injury Symposium 2024: Sports Medicine and Medical Readiness Section Summary

Collaboration between military and civilian investigators is necessary to develop strategies for optimizing treatments to diminish the sequelae of non-battle-related musculoskeletal injuries, which are highly prevalent among servicemembers. The 2024 Extremity War Injuries Symposium provided a forum whereby a diverse group of clinicians and researchers could develop strategies for optimizing treatments and diminishing the sequelae of conditions that are highly prevalent among active individuals. Key points were as follows: 1. The value of collaborations between military and civilian investigators cannot be overemphasized. These synergies can leverage the capabilities of established infrastructures in order to answer important questions pertaining to short-term outcomes-for example, warrior readiness of anterior cruciate ligament reconstructions among servicemembers and long-term posttraumatic osteoarthritis (PTOA) outcomes among civilian cohorts. 2. Current and future prospective trials will inform future treatment decisions related to multiligamentous knee injuries and glenohumeral instability. 3. Novel approaches to addressing PTOA in the acute postinjury period will need longitudinal surveillance to measure their impact on improving clinical outcomes and diminishing residual functional deficits.

Risk factors for recurrence following arthroscopic Bankart repair: a systematic review

BACKGROUND

Recurrent instability remains a major source of morbidity following arthroscopic Bankart repair. Many risk factors and predictive tools have been described, but there remains a lack of consensus surrounding individual risk factors and their contribution to outcomes. The purpose of this study is to systematically review the literature to identify and quantify risk factors for recurrence following arthroscopic Bankart repair.

METHODS

A literature search was performed using the PubMed/MEDLINE databases based on the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) guidelines. Studies were included if they evaluated risk factors for recurrent instability following arthroscopic Bankart repair.

RESULTS

Overall, 111 studies were included in the analysis, including a total of 19,307 patients and 2750 episodes of recurrent instability with 45 risk factors described. Age at operation was reported by 60 studies, with 35 finding increased risk at younger ages. Meta-analysis showed a 2-fold recurrence rate of 27.0% (171 of 634) for patients <20 years old compared with 13.3% (197 of 1485) for older patients (P < .001). Seventeen studies completed multivariable analysis, 13 of which were significant (odds ratio 1.3-14.0). Glenoid bone loss was evaluated by 39 studies, with 20 finding an increased risk. Multivariable analysis in 9 studies found odds ratios ranging from 0.7 to 35.1; 6 were significant. Off-track Hill-Sachs lesions were evaluated in 21 studies (13 significant), with 3 of 4 studies that conducted multivariable analysis finding a significant association with odds ratio of 2.9-8.9 of recurrence. The number of anchors used in repair was reported by 25 studies, with 4 finding increased risk with fewer anchors. Pooled analysis demonstrated a 25.0% (29 of 156) risk of recurrence with 2 anchors, compared with 18.1% (89 of 491) with 3 or more anchors (P = .06). Other frequently described risk factors included glenohumeral joint hyperlaxity (46% of studies reporting a significant association), number of preoperative dislocations (31%), contact sport participation (20%), competitive sport participation (46%), patient sex (7%), and concomitant superior labral anterior-posterior tear (0%).

CONCLUSION

Younger age, glenoid bone loss, and off-track Hill-Sachs lesions are established risk factors for recurrence following arthroscopic Bankart repair. Other commonly reported risk factors included contact and competitive sports participation, number of fixation devices, and patient sex.

Management of bone loss in anterior shoulder instability

Bone defects are frequently observed in anterior shoulder instability. Over the last decade, knowledge of the association of bone loss with increased failure rates of soft-tissue repair has shifted the surgical management of chronic shoulder instability. On the glenoid side, there is no controversy about the critical glenoid bone loss being 20%. However, poor outcomes have been described even with a subcritical glenoid bone defect as low as 13.5%. On the humeral side, the Hill-Sachs lesion should be evaluated concomitantly with the glenoid defect as the two sides of the same bipolar lesion which interact in the instability process, as described by the glenoid track concept. We advocate adding remplissage to every Bankart repair in patients with a Hill-Sachs lesion, regardless of the glenoid bone loss. When critical or subcritical glenoid bone loss occurs in active patients (> 15%) or bipolar off-track lesions, we should consider anterior glenoid bone reconstructions. The techniques have evolved significantly over the last two decades, moving from open procedures to arthroscopic, and from screw fixation to metal-free fixation. The new arthroscopic techniques of glenoid bone reconstruction procedures allow precise positioning of the graft, identification, and treatment of concomitant injuries with low morbidity and faster recovery. Given the problems associated with bone resorption and metal hardware protrusion, the new metal-free techniques for Latarjet or free bone block procedures seem a good solution to avoid these complications, although no long-term data are yet available.

Functional Anatomy and Biomechanics of Shoulder Instability

The glenohumeral joint is the least congruent and least constrained joint with a complex relationship of static and dynamic stabilizers to balance its native mobility with functional stability. In the young athlete, anterior shoulder instability is multifactorial and can be a challenge to treat, requiring a patient-specific treatment approach. Surgical decision-making must consider patient-specific factors such as age, sport activity and level, underlying ligamentous laxity, and goals for return to activity, in addition to careful scrutiny of the underlying pathology to include humeral and glenoid bone loss and surrounding scapular bone morphology.

Longer peripheral-track lesions are associated with instability after arthroscopic Bankart repair

BACKGROUND

The glenoid track concept has enabled the categorization of Hill-Sachs lesions (HSLs) into on-track lesions and off-track lesions. Furthermore, among the on-track lesions, further categorization has been established based on the distance from the medial edge of the Hill-Sachs lesion to the medial edge of the glenoid track, into peripheral-track lesions and central-track lesions. Recent studies on peripheral-track lesions and central-track lesions within the glenoid track have shown inconsistencies in failure rates, which deserves further investigation.

METHODS

A retrospective cohort comparison of patients who underwent arthroscopic Bankart repair between 2015 and 2020 was performed. 102 patients with peripheral-track HSLs were included. The patients were divided into 2 groups based on the results of the postoperative apprehension test: the apprehension positive group (n = 30), and the apprehension negative group (n = 72). Using preoperative computed tomography (CT) and an image reconstruction program, 3-dimensional (3D) images were segmented to calculate the length, width, depth, and distance of the HSLs. A multivariate logistic regression was used to determine the risk factors of recurrence, for which odds ratio (OR) and 95% confidence interval (CI) were provided.

RESULTS

A multivariate logistic regression analysis revealed that the length of the peripheral-track HSLs was a significant independent predictor of failure in this study. (OR 1.380; 95% CI 1.170-1.627; P < .001). The receiver operating characteristics curve (ROC) demonstrated a predictive power (area under the curve = 0.841) and a threshold value of 14.2 mm.

CONCLUSION

Length was the only risk factor for the recurrent instability of peripheral-track HSLs after ABR. In the context of surgical decision-making, utilizing the glenoid track concept, medical practitioners may need to evaluate instability by considering the length as a continuous factor, while differentiating between peripheral-track and central-track classifications.

Glenohumeral morphological predictors of recurrent shoulder instability following arthroscopic Bankart repair

PURPOSE

The purpose of this study was to evaluate glenohumeral morphological features on a magnetic resonance arthrogram (MRA) to determine risk factors for recurrence of anterior shoulder instability following arthroscopic Bankart repair (ABR).

METHODS

A retrospective review of patients who underwent ABR between 2012 and 2017 was performed to identify patients who had recurrence of instability following stabilisation (Group 1). These were pair-matched in a 2:1 ratio for age, gender and sport with a control (Group 2) who underwent ABR without recurrence. Preoperative MRAs were evaluated for risk factors for recurrence, with glenoid bone loss and Hill-Sachs lesions also measured. Multilinear and multilogistic regression models were used to evaluate factors affecting recurrence.

RESULTS

Overall, 72 patients were included in this study, including 48 patients without recurrence and 24 patients with recurrent instability. There was a significant difference between the two groups in mean glenoid bone loss (Group 1: 7.3% vs. Group 2: 5.7%, p < 0.0001) and the rate of off-track Hill-Sachs lesions (Group 1: 20.8% vs. Group 2: 0%, p = 0.0003). Of the variables analysed in logistic regression, increased glenoid anteversion (p = 0.02), acromioclavicular (AC) degeneration (p = 0.03) and increased Hill-Sachs width were associated with increased risk of failure. Increased chondral version (p = 0.01) and humeral head diameter in the anteriorposterior view were found to be protective and associated with a greater likelihood of success.

CONCLUSION

Glenoid anteversion was a risk factor for recurrent instability, whereas increased chondral version and humeral head diameter were associated with higher rates of success following ABR. Glenoid bone loss, presence of an off-track Hill-Sachs lesion, increased Hill-Sachs width and AC degeneration were also associated with failure. These findings should be used by surgeons to stratify risk for recurrence following ABR.

LEVEL OF EVIDENCE

Level III.

Arthroscopic Latarjet Versus Arthroscopic Free Bone Block Procedures for Anterior Shoulder Instability: A Proportional Meta-analysis Comparing Recurrence, Complication, and Reoperation Rates

BACKGROUND

Several arthroscopic glenoid bone augmentation techniques have been introduced to treat patients affected by anterior shoulder instability associated with critical bone loss. The efficacy of the different arthroscopic bony procedures has not been compared yet.

PURPOSE

To compare the recurrence, complication, and reoperation rates of the arthroscopic Latarjet (AL) and arthroscopic free bone block (ABB) procedures for anterior shoulder instability.

STUDY DESIGN

Meta-analysis and systematic review; Level of evidence, 4.

METHODS

A systematic search was conducted in MEDLINE/PubMed, Web of Science, and Embase to identify clinical studies reporting the outcomes of the AL and ABB procedures. The following search phrases were used: "Arthroscopic" AND "Bone Block" OR "Bone Graft," and "Arthroscopic" AND "Glenoid Augmentation" OR "Glenoid Reconstruction," and "Arthroscopic" AND "Latarjet" OR "Coracoid Graft" OR "Coracoid Transfer." Exclusion criteria were <24 months of minimum follow-up, sample size <10 cases, revision after previous glenoid bone grafting, epilepsy, and multidirectional instability. Data regarding the study design, patient characteristics, surgical technique, and outcomes were extracted and analyzed. A proportional meta-analysis was conducted to compare the complication, recurrence, and reoperation rates between the 2 groups. Multiple subgroup analyses were performed to analyze the incidence of each complication and assess the weight of different fixation methods (in the whole cohort) or different graft types (in the ABB group). The modified Coleman Methodology Score was used to assess the risk of bias.

RESULTS

Of 5010 potentially relevant studies, 18 studies regarding the AL procedure (908 cases) and 15 studies regarding the ABB procedure (469 cases) were included. The 2 groups were comparable in age (P = .07), sex (P = .14), glenoid bone loss (P = .14), number of preoperative dislocations (P = .62), proportion of primary and revision procedures (P = .95), length of follow-up (P = .81), modified Coleman Methodology Score (P = .21), and level of evidence (P = .49). There was no difference in the recurrence (P = .88), reoperation (P = .79), and complication (P = .08) rates. The subgroup analyses showed a higher rate of hardware-related complications for screw fixation compared with flexible fixation (P = .01).

CONCLUSION

The AL and ABB procedures had similar recurrence, reoperation, and complication rates. Screw fixation of the bone graft was related to an increased risk of complications compared with flexible fixation.

REGISTRATION

CRD42022368153 (PROSPERO).

Glenoid track and subcritical Hill-Sachs lesion

Background

We have proposed the concept of glenoid track ("on-track/off-track" lesion) to evaluate the risk of engagement of the Hill-Sachs lesion with the glenoid after arthroscopic Bankart repair. This concept has been widely used and many clinical validation studies have been reported. To measure the glenoid track width, we have recommended to use 3-dimensional computed tomography (CT) images. However, the CT method has the issue of radiation exposure and involves time and effort to make 3-dimensional CT images from 2-dimensional images. For these reasons, there are several reports describing the measurement method using magnetic resonance imaging. Recently, the threshold of the critical glenoid bone loss becomes lower. A zone of bone loss below the critical size is called "subcritical bone loss", which might be related to deterioration of quality of life and bone grafting is recommended. We applied the concept of "subcritical bone loss" to the glenoid track. Patients with "on-track" lesions can be divided into 2 subgroups: those with a "peripheral-track" lesion (most medial 1/4) and those with a "central-track" lesion (the rest 3/4). More recently, similar evaluation methods to evaluate the risk of "off-track" lesions have been reported: ''distance to dislocation'' and "Hill-Sachs interval/glenoid track ratio". Also, similar concept to "peripheral-track" lesion, "near-track" lesion was reported. The concept of "peripheral-track" lesion is a concept of assessing an "on-track" lesion which is very close to the medial margin of the glenoid track (subcritical bone loss).

Methods

Similar evaluation methods to evaluate the risk of "off-track" or "peripheral-track" lesions were proposed in the literature. A review was performed by searching PubMed. Journal articles published between January 2014 and January 2023 were taken into account. They were compared and their differences were explained.

Results

The "near-track" lesion concept is similar to "peripheral-track" lesion. However, the cutoff value is different: Hill-Sachs occupancy ≥ 75% is the "peripheral-track" lesion, whereas "distance to dislocation" < 8 mm is the "near-track" lesion.

Conclusion

We introduced update of the glenoid track concept including the evaluation method, peripheral-track lesion, and its clinical application.

The glenoid track concept is insufficient to predict Bankart failures: a computed tomography scan study

Background

The glenoid track concept identifies patients with "off-track" (engaging) Hill-Sachs lesions (HSLs) as poor candidates for arthroscopic Bankart repair (ABR) due to the high risk of shoulder instability recurrence.

Purpose

To retrospectively calculate the glenoid track index, using preoperative computed tomography (CT) scans, in a cohort of patients with failed ABR. We hypothesized that all patients with a failed ABR would have engaging ("off-track") HSLs on preoperative CT scan.

Type of Study

CT scan study.

Methods

Preoperative CT scan of 45 patients, seen in our facility for failed ABR, was used to retrospectively calculate the glenoid track index. The risk of recurrence was also calculated for each patient using Instability Severity Index Score (ISI-Score) and Glenoid Track Instability Management Score (GTIMS). There were 37 failed isolated ABRs and 8 associated HS remplissage. The mean t age at surgery was 24 years (range, 15-52) and instability recurred at a mean of 29 months postoperative (range, 3-167).

Results

Preoperative CT scan imaging identified "off-track" bony lesions in 85% of patients (38/45) and "on-track" lesions in 15% (7/45). No significant differences were noted between the 2 groups (off-track vs. on-track) regarding patient age, hyperlaxity, sports participation, size of HS lesion, or ISI-Score. The mean glenoid bone loss was 15.7% (range, 4-36%) with mean HS width was greater than 20 mm in 66% of CT scans. The preoperative ISI-Score was predictive of failures (>3 points in all patients) with no difference between on-track and off-track patients (6.3 ± 1.7 vs. 6.6 ± 1.7, P = .453). By contrast, the GTIMS did not predict failures as there was a significant difference between GTIMS for on-track and off-track patients (2.1 ± 1.3 vs. 6.6 ± 1.7).

Conclusions

The glenoid track concept alone is insufficient to predict Bankart failures: in the present series of failed ABR, 15% of shoulders had "on-track" (non-engaging) lesions on preoperative CT scan. In patients, with "on-track" bony lesions, the ISI-Score is a useful predictive tool to detect patients at risk of failure, while the GTIMS is not.

Defining Critical Humeral Bone Loss: Inferior Craniocaudal Hill-Sachs Extension as Predictor of Recurrent Instability After Primary Arthroscopic Bankart Repair

BACKGROUND

The glenoid track concept for shoulder instability primarily describes the medial-lateral relationship between a Hill-Sachs lesion and the glenoid. However, the Hill-Sachs position in the craniocaudal dimension has not been thoroughly studied.

HYPOTHESIS

Hill-Sachs lesions with greater inferior extension are associated with increased risk of recurrent instability after primary arthroscopic Bankart repair.

STUDY DESIGN

Case-control study; Level of evidence, 3.

METHODS

The authors performed a retrospective analysis of patients with on-track Hill-Sachs lesions who underwent primary arthroscopic Bankart repair (without remplissage) between 2007 and 2019 and had a minimum 2-year follow-up. Recurrent instability was defined as recurrent dislocation or subluxation after the index procedure. The craniocaudal position of the Hill-Sachs lesion was measured against the midhumeral axis on sagittal magnetic resonance imaging (MRI) using either a Hill-Sachs bisecting line through the humeral head center (sagittal midpoint angle [SMA], a measure of Hill-Sachs craniocaudal position) or a line tangent to the inferior Hill-Sachs edge (lower-edge angle [LEA], a measure of Hill-Sachs caudal extension). Univariate and multivariate regression were used to determine the predictive value of both SMA and LEA for recurrent instability.

RESULTS

In total, 176 patients were included with a mean age of 20.6 years, mean follow-up of 5.9 years, and contact sport participation of 69.3%. Of these patients, 42 (23.9%) experienced recurrent instability (30 dislocations, 12 subluxations) at a mean time of 1.7 years after surgery. Recurrent instability was found to be significantly associated with LEA >90° (ie, Hill-Sachs lesions extending below the humeral head equator), with an OR of 3.29 (P = .022). SMA predicted recurrent instability to a lesser degree (OR, 2.22; P = .052). Post hoc evaluation demonstrated that LEA >90° predicted recurrent dislocations (subset of recurrent instability) with an OR of 4.80 (P = .003). LEA and SMA were found to be collinear with Hill-Sachs interval and distance to dislocation, suggesting that greater LEA and SMA proportionally reflect lesion severity in both the craniocaudal and medial-lateral dimensions.

CONCLUSION

Inferior extension of an otherwise on-track Hill-Sachs lesion is a highly predictive risk factor for recurrent instability after primary arthroscopic Bankart repair. Evaluation of Hill-Sachs extension below the humeral equator (inferior equatorial extension) on sagittal MRI is a clinically facile screening tool for higher-risk lesions with subcritical glenoid bone loss. This threshold for critical humeral bone loss may inform surgical stratification for procedures such as remplissage or other approaches for at-risk on-track lesions.

How does dynamic arthroscopic tracking compare with radiologic glenoid track for identification of on- and off-track lesions in anterior shoulder instability?

BACKGROUND

Current treatment paradigms for anterior shoulder instability are based on radiologic measurements of glenohumeral bone defects, and mathematical calculation of the glenoid track (GT) is used to classify lesions into on-track and off-track morphology. However, radiologic measurements have shown high variability, and GT widths under dynamic conditions have been reported to be significantly smaller than those under static radiologic conditions. The purpose of this study was to assess the reliability, reproducibility, and diagnostic validity of dynamic arthroscopic standardized tracking (DAST) in comparison to the gold-standard radiologic track measurement method for the identification of on- and off-track bony lesions in patients with anteroinferior shoulder instability.

METHODS

Between January 2018 and August 2022, 114 patients with traumatic anterior shoulder instability were evaluated using 3-T magnetic resonance imaging or computed tomography scans; glenoid bone loss, Hill-Sachs interval, GT, and Hill-Sachs occupancy ratio (HSO) were measured, and defects were classified as on-track or off-track defects and peripheral-track defects (based on HSO percentage) by 2 independent researchers. During arthroscopy, a standardized method (DAST method) was used by 2 independent observers to classify defects into on-track defects (central and peripheral) and off-track defects. Interobserver reliability of the DAST and radiologic methods was calculated using the κ statistic and reported as percentage agreement. Diagnostic validity (sensitivity, specificity, positive predictive value, and negative predictive value) of the DAST method was calculated using the radiologic track (HSO percentage) as the gold standard.

RESULTS

The radiologically measured mean glenoid bone loss percentage, Hill-Sachs interval, and HSO in off-track lesions were lower with the arthroscopic method (DAST) as compared with the radiologic method. The DAST method showed nearly perfect agreement between the 2 observers for the on-track/off-track classification (κ = 0.96, P < .001) and the on-track central or peripheral /off-track classification (κ = 0.88, P < .001). The radiologic method showed greater interobserver variability (κ = 0.31 and κ = 0.24, respectively) with only fair agreement for both classifications. Inter-method agreement varied between 71% and 79% (95% confidence interval, 62%-86%) between the 2 observers, and reliability was assessed as slight (κ = 0.16) to fair (κ = 0.38). Overall, for identification of an off-track lesion, the DAST method showed maximum specificity (81% and 78%) when radiologic peripheral-track lesions (HSO percentage of 75%-100%) were considered off-track and showed maximum sensitivity when arthroscopic peripheral-track lesions were classified as off-track.

CONCLUSION

Although inter-method agreement was low, a standardized arthroscopic tracking method (DAST method) showed superior interobserver agreement and reliability for lesion classification in comparison to the radiologic track method. Incorporating DAST into current algorithms may help reduce variability in surgical decision making.

Surgical Intervention Following a First Traumatic Anterior Shoulder Dislocation Is Worthy of Consideration

Up to 60% of patients experience recurrence after a first traumatic anterior shoulder dislocation (FTASD), which is often defined as having experienced either dislocation or subluxation. Thus surgical intervention after FTASD is worthy of consideration and is guided by the number of patients who need to receive surgical intervention to prevent 1 redislocation (i.e., number needed to treat), (subjective) health benefit, complication risk, and costs. Operative intervention through arthroscopic stabilization can be successful in reducing recurrence risk in FTASD, as has been shown in multiple randomized controlled trials. Nevertheless, there is a large "gray area" for the indication of arthroscopic stabilization, and it is therefore heavily debated which patients should receive operative treatment. Previous trials showed widely varying redislocation rates in both the intervention and control group, meta-analysis shows 2% to 19% after operative and 20% to 75% after nonoperative treatment, and redislocation rates may not correlate with patient-reported outcomes. The literature is quite heterogeneous, and a major confounder is time to follow-up. Furthermore, there is insufficient standardization of reporting of outcomes and no consensus on definition of risk factors. As a result, surgery is a reasonable intervention for FTASD patients, but in which patients it best prevents redislocation requires additional refinement.

Recurrent Instability After Arthroscopic Bankart Repair in Patients With Hyperlaxity and Near-Track Lesions

Background

Recurrent anterior shoulder instability after arthroscopic Bankart repair presents a challenging clinical problem, with the primary stabilization procedure often portending the best chance for clinical success.

Purpose

To determine if capsuloligamentous laxity affects failure (recurrent dislocation, subluxation, and/or perceived instability symptoms) after arthroscopic Bankart repair in patients with near-track lesions (ie, those with smaller distance to dislocation [DTD]).

Study Design

Case-control study; Level of evidence, 3.

Methods

The authors retrospectively reviewed consecutive patients who underwent primary arthroscopic Bankart repair for recurrent anterior glenohumeral instability at a single institution between 2007 and 2019 and who had at least 2 years of follow-up data. Patients with glenoid bone loss >20%, off-track lesions, concomitant remplissage, or rotator cuff tear were excluded. Capsuloligamentous laxity, or hyperlaxity, was defined as external rotation >85° with the arm at the side and/or grade ≥2 in at least 2 planes with the shoulder at 90° of abduction. Near-track lesions were defined as those with a DTD <10 mm.

Results

Included were 173 patients (mean age, 20.5 years; mean DTD, 16.2 mm), of whom 16.8% sustained a recurrent dislocation and 6.4% had recurrent subluxations (defined as any subjective complaint of recurrent instability without frank dislocation), for an overall recurrent instability rate of 23.1%. The rate of revision stabilization was 15.6%. The mean time to follow-up was 7.4 years. Independent predictors of recurrent instability were younger age (P = .001), smaller DTD (P = .021), >1 preoperative instability episode (P < .001), and the presence of hyperlaxity during examination under anesthesia (P = .013). Among patients with near-track lesions, those with hyperlaxity had a recurrent instability rate almost double that of patients without hyperlaxity (odds ratio, 34.1; P = .04). The increased rate of failure and recurrent dislocation in the near-track hyperlaxity cohort remained elevated, even in patients with no bone loss.

Conclusion

Capsuloligamentous shoulder laxity was a significant independent risk factor for failure after primary arthroscopic Bankart repair without remplissage and was more predictive of failure in patients with versus without near-track lesions.

Assessment of Thresholds for Clinically Relevant Change in the Pediatric/Adolescent Shoulder Survey After Shoulder Instability Surgery: Factors Associated With Meaningful Improvement in Outcomes

Background

The pediatric/adolescent shoulder survey (PASS) score is a subjective measure of shoulder symptomology in younger patients.

Purpose

To establish the minimal clinically important difference (MCID) and minimal detectable change (MDC) for the PASS score in adolescents after surgical treatment for shoulder instability.

Study Design

Case series; Level of evidence, 4.

Methods

Included were patients aged 12.5 to 23 years who underwent surgical treatment for shoulder instability and who had completed PASS forms preoperatively and at 3 months postoperatively. The MCID was established using an anchor-based approach, with the Single Assessment Numeric Evaluation (SANE) and shortened version of the Disabilities of the Arm, Shoulder and Hand (QuickDASH) as anchors. Change in PASS score between anchor groups was determined using receiver operating characteristic curve analysis. MDC with 90% confidence (MDC90) was also calculated. Range of motion and strength data at 3-month follow-up were evaluated to identify the optimal postoperative PASS score. Factors associated with improvement in PASS score beyond the MDC90 and MCID were determined in a subset of patients with ≥6-month follow-up data.

Results

A total of 95 patients were included. The mean PASS score improved significantly from preoperatively to postoperatively (57 ± 15 to 75 ± 16; P < .001). The anchor-based MCID ranged from 12.5 to 13.2 points, with an area under the receiver operating characteristic (AUC) curve of 0.87 for the SANE and 0.99 for the QuickDASH. The MDC90 was 16.5 points. The optimal PASS score at 3 months after surgery was ≥85 (AUC, 0.66). Shorter duration of symptoms, lower preoperative forward elevation, and higher preoperative external rotation were associated with improvement in PASS score above the MDC90 and/or MCID for the subset of patients (n = 25) with ≥6-month follow-up data. Increased number of suture anchors, less preoperative external rotation deficit, and number of previous dislocations had a moderate effect on improvement in outcomes.

Conclusion

A postoperative increase in PASS score of ≥16.5 points had a 90% chance of being a true-positive change, while a score change of approximately 13 points was likely clinically relevant. The optimal PASS score after surgery was ≥85. Shorter duration of symptoms, preoperative range of motion, number of surgical anchors, and number of previous dislocations were associated with achieving a clinically relevant improvement in PASS score at minimum 6 months postoperatively.

Glenoid Track Assessment at Imaging in Anterior Shoulder Instability: Rationale and Step-by-Step Guide

Anterior shoulder dislocation is the most common form of joint instability in humans, usually resulting in soft-tissue injury to the glenohumeral capsuloligamentous and labral structures. Bipolar bone lesions in the form of fractures of the anterior glenoid rim and posterolateral humeral head are often associated with anterior shoulder dislocation and can be a cause or result of recurrent dislocations. Glenoid track assessment is an evolving concept that incorporates the pathomechanics of anterior shoulder instability into its management. Currently widely endorsed by orthopedic surgeons, this concept has ramifications for prognostication, treatment planning, and outcome assessment of anterior shoulder dislocation. The glenoid track is the contact zone between the humeral head and glenoid during shoulder motion from the neutral position to abduction and external rotation. Two key determinants of on-track or off-track status of a Hill-Sachs lesion (HSL) are the glenoid track width (GTW) and Hill-Sachs interval (HSI). If the GTW is less than the HSI, an HSL is off track. If the GTW is greater than the HSI, an HSL is on track. The authors focus on the rationale behind the glenoid track concept and explain stepwise assessment of the glenoid track at CT or MRI. Off-track to on-track conversion is a primary goal in stabilizing the shoulder with anterior instability. The key role that imaging plays in glenoid track assessment warrants radiologists' recognition of this concept along with its challenges and pitfalls and the production of relevant and actionable radiology reports for orthopedic surgeons-to the ultimate benefit of patients. ©RSNA, 2023 Online supplemental material is available for this article. Quiz questions for this article are available through the Online Learning Center.

Editorial Commentary: High Variability Exists Among Different Techniques for Measuring Glenoid Bone Loss

Glenoid bone loss is a predominant factor in determining proper surgical management for glenohumeral instability. Precise measurements of glenoid (and humeral) bone defects are fundamental, and millimeters matter. Three-dimensional computed tomography scans may provide the highest interobserver reliability for making these measurements. Yet, because imprecision in the range of millimeters is observed with even the most precise glenoid bone loss measurement techniques, it could be a mistake to over-rely, let alone solely rely, on glenoid bone loss measurement as the primary determinant for selecting one surgical procedure over another. Surgeons must measure glenoid bone loss but also thoughtfully consider patient age, associated soft-tissue injuries, and activity level, including throwing and participation in collision sports. When choosing the proper surgical procedure for a shoulder instability patient, we should not focus on only one variably measured parameter but, instead, on a comprehensive assessment of the patient.

"Nearly off-track lesions" or a short distance from the medial edge of the Hill-Sachs lesion to the medial edge of the glenoid track does not seem to be accurate in predicting recurrence after an arthroscopic Bankart repair in a military population: a case-control study

BACKGROUND

On-track lesions with a short distance from the medial edge of the Hill-Sachs lesion to the medial edge of the glenoid track (nearly off-track) may predispose recurrence after arthroscopic Bankart repair (ABR) in the general population. The aim of this study was to determine if a shorter distance between the medial edge of the Hill-Sachs lesion and the medial edge of the glenoid track could accurately predict recurrence after an ABR in a high-demand military population. It was hypothesized that a shorter distance would not accurately predict recurrence.

MATERIALS AND METHODS

A retrospective monocenter case-control study was performed at the Dutch Central Military Hospital. Patients with an on-track Hill-Sachs lesion who underwent a primary ABR between 2014 and 2019 with a minimal follow-up of 2 years and a preoperative magnetic resonance imaging (MRI) assessment received a questionnaire. The primary outcome was recurrence, defined as a complete dislocation or subluxation. Glenoid bone loss was assessed using a linear-based method on MRI. The distance from the medial edge of the Hill-Sachs lesion to the medial edge of the glenoid track was defined as the distance to dislocation (DTD). A receiver operating characteristic curve was created to determine the predictive value of the DTD for recurrence. Logistic regression was used to determine preoperative risk factors that predispose recurrence. Covariates were selected based on univariable analysis and included gender, body mass index, age at surgery and first dislocation, laterality, smoking habits, overhead shoulder activity during work, preoperative dislocations, sports type and level, bony or labral lesions on MRI, and DTD.

RESULTS

In total, 80 patients with an average follow-up of 4.8 ± 1.9 years completed the questionnaire and were included in the analyses. Seventeen patients (21%) experienced recurrence at the final follow-up. No difference in DTD was observed among patients who experienced recurrence (9 ± 4 mm) compared with patients who did not (9 ± 5 mm; P = .81). The receiver operating characteristic curve demonstrated no predictive power of DTD for recurrence (area under the curve = 0.49). Smoking at the time of surgery (odds ratio: 3.9; confidence interval: 1.2-12.7; P = .02) and overhead shoulder movement during work (odds ratio: 9.3; confidence interval: 1.1-78.0; P = .04) were associated with recurrence according to the logistic regression analysis.

CONCLUSION

A shorter DTD demonstrated no accuracy in predicting recurrence in a military population. Smoking at the time of surgery and overhead shoulder activity during work were associated with recurrence; however, these analyses were underpowered to draw valid conclusions.

Editorial Commentary: Urgency Toward Arthroscopic Bankart Repair Is Essential for Anterior Shoulder Dislocation: You Don't Have to Fix After the First Dislocation, but Definitely Before the Second!

While still hotly debated, primary arthroscopic management of the first-time anterior shoulder dislocation has an extensive list of known benefits: lower overall health care costs, improved patient-reported outcomes, a vast reduction in secondary instability, and higher quality-of-life measures. Yet, despite these meaningful contributions to health care quality, we continue to bypass the predictable success of an acute arthroscopic Bankart repair in order to tempt fate with "a trial" of nonoperative care for our young, high-risk collision athletes. Whether for the in-season athlete, the "early responder" with limited apprehension, subluxations with spontaneous reduction, or those stoically committed to nonsurgical care, we as physicians are often complicit in this shared risk taking and ceremonial weighing of the risks and benefits for treatment options after primary shoulder instability. Even just 1 additional episode of instability recurrence can double (or triple) the rate of glenohumeral bone loss. Furthermore, subsequent anterior shoulder instability compromises subjective shoulder function, heightens risk of secondary recurrence and/or revision, and increases the likelihood of requiring more advanced surgical management, such as with a Latarjet or other anterior bone block procedure. We must maintain a sense of urgency toward surgical treatment, particularly in young, high-demand athletes with persistent instability. To parrot the wisdom of our shoulder mentors, hear my humble plea: you don't have to fix the shoulder after the first anterior dislocation, but you should definitely do it before the second!

Increased Failure Rates After Arthroscopic Bankart Repair After Second Dislocation Compared to Primary Dislocation With Comparable Clinical Outcomes

PURPOSE

The purpose of this study was to compare rates of recurrent dislocation and postsurgical outcomes in patients undergoing arthroscopic Bankart repair for anterior shoulder instability immediately after a first-time traumatic anterior dislocation versus patients who sustained a second dislocation event after initial nonoperative management.

METHODS

A retrospective chart review was performed of patients undergoing primary arthroscopic stabilization for anterior shoulder instability without concomitant procedures and minimum 2-year clinical follow-up. Primary outcome was documentation of a recurrent shoulder dislocation. Secondary clinical outcomes included range of motion, Visual Analog Scale (VAS), American Shoulder and Elbow Surgeons Shoulder Score (ASES), and Shoulder Activity Scale (SAS).

RESULTS

Seventy-seven patients (mean age 21.3 years ± 7.3 years) met inclusion criteria. Sixty-three shoulders underwent surgical stabilization after a single shoulder dislocation, and 14 underwent surgery after 2 dislocations. Average follow-up was 35.9 months. The rate of recurrent dislocation was significantly higher in the 2-dislocation group compared to single dislocations (42.8% vs 14.2%, P = .03). No significant difference was present in range of motion, VAS, ASES, and SAS scores. The minimal clinically important difference (MCID) was 1.4 for VAS and 1.8 for SAS scores. The MCID was met or exceeded in the primary dislocation group in 31/38 (81.6%) patients for VAS, 23/31 (74.1%) for ASES, and 24/31 for SES (77.4%) scores. For the second dislocation cohort, MCID was met or exceeded in 7/9 (77.8%) for VAS, 4/7 (57.1%) for ASES, and 5/7 for SES (71.4%) scores.

CONCLUSION

Immediate arthroscopic surgical stabilization after a first-time anterior shoulder dislocation significantly decreases the risk of recurrent dislocation in comparison to those who undergo surgery after 2 dislocation events, with comparable clinical outcome scores. These findings suggest that patients who return to activities after a primary anterior shoulder dislocation and sustain just 1 additional dislocation event are at increased risk of a failing arthroscopic repair.

STUDY DESIGN

Retrospective comparative study; Level of evidence, 3.

Disagreement Between the Accepted Best-Fit Circle Method to Calculate Bone Loss Between Injured and Uninjured Shoulders

BACKGROUND

No study has evaluated whether best-fit circles based on glenoids with defects accurately represent normal inferior glenoids before injury.

PURPOSE

To investigate whether the best-fit circles on the affected side with a glenoid defect can accurately represent native glenoids before injury.

STUDY DESIGN

Cohort study (diagnosis); Level of evidence, 3.

METHODS

This retrospective study included 58 patients with unilateral recurrent anterior shoulder instability. First, we compared the diameter of best-fit circles based on affected and unaffected glenoids. Glenoid defect sizes based on each best-fit circle were then calculated and compared. Second, we created serial virtual glenoid defects (10%, 15%, 20%, 25%) on unaffected glenoids and compared diameters of best-fit circles on the glenoids before and after virtual defects. We also analyzed and compared the size of virtual and calculated glenoid defects. Bland-Altman plots and intraclass coefficients (ICCs) were used to compare and analyze agreement of measurements. After categorization of glenoid defects based on clinical cutoff values, Cohen κ and percentage agreement were calculated.

RESULTS

The diameter of 55.2% (32/58) of best-fit circles from affected glenoids over- or underestimated the diameter on the unaffected side by >5%. In 28 of the 32 patients, the diameter of the affected side circle was overestimated. Consequently, 41.4% (24/58) of glenoid defects were over- or underestimated by >5%. In 19 of the 24 patients, the glenoid defect from the affected side was >5% larger. ICCs between sides for best-fit circle diameters and defect sizes were 0.632 and 0.800, respectively. Agreement of glenoid defect size between sides was 58.6% (34/58) overall, but when the defect was ≥10%, agreement decreased to 32.3% (10/31). Among 232 glenoids with virtual defects created from 58 normal glenoids, the diameter of 31.0% (72/232) of best-fit circles and the size of 11.6% (27/232) of defects were over- or underestimated by >5%.

CONCLUSION

When assessing glenoid defects in anterior shoulder instability, best-fit circles based on affected glenoids do not always represent the native glenoid and may thus lead to inaccurate circle sizes and defect estimates.

Arthroscopic Bankart Repair for Adolescent Anterior Shoulder Instability: Clinical and Imaging Predictors of Revision Surgery and Recurrent Subjective Instability

BACKGROUND

Multiple clinical and radiologic risk factors for recurrent instability after arthroscopic Bankart repair have been described. Humeral bone loss has gained more recent attention, particularly with respect to "off-track" lesions and increased rates of recurrent instability and revision surgery.

PURPOSE

To evaluate clinical and radiologic predictors of failure after arthroscopic Bankart repair in adolescents.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

A single-institution retrospective study was performed in patients <19 years of age treated with arthroscopic Bankart repair from 2011 to 2017. Magnetic resonance imaging measurements of glenoid and humeral bone loss, the glenoid track, and the presence of off-track Hill-Sachs (HS) lesions were assessed. All patients had a minimum follow-up of 24 months and completed patient-reported outcome scores. Failure was defined as revision surgery or postoperative subjective instability.

RESULTS

A total of 59 patients (46 male, 13 female) with a median age of 16 years (range, 12-18 years) were included. Ten patients (17%) had revision surgery and 8 patients (14%) had subjective instability without revision surgery. No clinical or radiologic factors were significantly different between the failure cohort and the nonfailure cohort. Four patients (7%) measured off-track, and 2 of these patients experienced failure. A total of 38 patients (64%) were identified to have an HS defect. Subgroup analysis of these patients identified a greater HS interval (HSI) in patients who underwent revision surgery as compared with those patients who did not have revision surgery. Among patients with GT ratio ≥15 mm, there was a 50% rate of revision surgery. The Pediatric/Adolescent Shoulder Survey (PASS) and Single Assessment Numeric Evaluation (SANE) scores at the final follow-up were not significantly different among patients with or without revision surgery. However, those with subjective instability who had not undergone revision surgery had significantly lower PASS and SANE scores as compared with the remainder of the cohort.

CONCLUSION

Of the adolescents in this cohort, 31% either had revision surgery (17%) or reported subjective feelings of instability (14%) after arthroscopic Bankart repair. Off-track instability was identified in 7% of the cohort but was not predictive of failure. Among the subgroup of patients with an HS defect, those who underwent revision surgery had a significantly larger HSI.

First-time traumatic anterior shoulder dislocation: current concepts

The management of first-time traumatic anterior shoulder dislocations has been a topic of extensive study yet remains controversial. Development of a treatment plan requires an understanding of patient-specific considerations, including demographics, functional demands, and extent of pathology. Each of these can influence rates of recurrence and return to activity. The purpose of this review is to provide a framework for decision-making following a first-time anterior shoulder dislocation, with particular focus on the high-risk young and athletic population. A summary of surgical treatment options and their outcomes is outlined, along with future biomechanical and clinical perspectives.

Distance to Dislocation and Recurrent Shoulder Dislocation After Arthroscopic Bankart Repair: Rethinking the Glenoid Track Concept

BACKGROUND

The "distance to dislocation" (DTD) calculation has been proposed as 1 method to predict the risk of recurrent dislocation after arthroscopic Bankart repair for an "on-track" shoulder. Rates of recurrent dislocation at specific DTD values are unknown.

HYPOTHESIS

Among patients with "on-track" shoulder lesions who underwent primary arthroscopic Bankart repair, the rate of recurrent dislocation would increase as DTD values decrease.

STUDY DESIGN

Case-control study; Level of evidence, 3.

METHODS

We performed a retrospective analysis of 188 patients with "on-track" shoulder lesions who underwent primary arthroscopic anterior labral repair between 2007 and 2019, with a minimum 2-year follow-up. Glenoid bone loss, Hill-Sachs interval, glenoid track, and DTD were determined from preoperative magnetic resonance imaging scans. The rate of recurrent dislocation was determined at 2-mm DTD intervals. Univariate and multivariate regression analyses were used to evaluate the relationship between recurrent dislocation, patient characteristics, and bone loss variables. A multivariate regression model was created to predict the probability of failure at continuous DTD values. A subgroup analysis of failure rate based on collision sports participation was also performed.

RESULTS

A total of 29 patients (15.4%) sustained recurrent dislocations. Patient age (P = .046), multiple dislocations (P = .03), glenoid bone loss (P < .001), Hill-Sachs interval length (P < .001), and DTD (P < .001) were all independent predictors of failure. As the DTD decreased, the rate of recurrent dislocation increased. Below a DTD threshold of 10 mm, the recurrent dislocation rate increased exponentially. Up to a threshold of 24 mm, the failure rate for collision athletes remained >12.3%, independent of the DTD. Conversely, the failure rate among noncollision athletes decreased steadily as the DTD increased.

CONCLUSION

For "on-track" shoulder lesions, as the DTD approached 0 mm ("off-track" threshold), the risk of recurrent dislocation after arthroscopic Bankart repair increased significantly. Below a DTD threshold of 10 mm, the risk of failure increased exponentially. The risk of recurrent dislocation for collision sports athletes remained elevated at higher DTD values than for noncollision athletes.

Glenoid Track Width Is Smaller Under Dynamic Conditions: An In Vivo Dual-Fluoroscopy Imaging Study

BACKGROUND

The glenoid track concept has been widely used to assess the risk of instability due to bipolar bone loss. The glenoid track width was commonly used as 83% of the glenoid width to determine if a lesion was on-track or off-track. However, the value was obtained under static conditions, and it may not be able to reflect the actual mechanism of traumatic dislocation during motion.

PURPOSE

To compare the glenoid track width under dynamic and static conditions using a dual-fluoroscopic imaging system.

STUDY DESIGN

Controlled laboratory study.

METHODS

In total, 40 shoulders of 20 healthy volunteers were examined for both dynamic and static tests within a dual-fluoroscopic imaging system at 5 different arm positions: 30°, 60°, 90°, 120°, and 150° of abduction, keeping the shoulder at 90° of external rotation. The participants performed a fast horizontal arm backswing for dynamic tests while keeping their arm in maximum horizontal extension for static tests. Computed tomography scans were used to create 3-dimensional models of the humerus and scapula for 2-dimensional to 3-dimensional image registration. Magnetic resonance imaging scans were obtained to delineate the medial margin of the rotator cuff insertion. The glenoid track width was measured as the distance from the anterior rim of the glenoid to the medial margin of the rotator cuff insertion and compared between static and dynamic conditions.

RESULTS

The mean glenoid track widths at 30°, 60°, 90°, 120°, and 150° of abduction were significantly smaller under dynamic conditions (88%, 81%, 72%, 69%, and 68% of the glenoid width) than those under static conditions (101%, 92%, 84%, 78%, and 77% of the glenoid width) (all P < .001). The glenoid track width significantly decreased with the increasing abduction angles in the range of 30° to 120° under static conditions (all P < .003) and 30° to 90° under dynamic conditions (all P < .001).

CONCLUSION

A smaller dynamic-based value should be considered for the glenoid track width when distinguishing on-track/off-track lesions. Clinical evidence is needed to establish the superiority of the dynamic-based value over the static-based value as an indicator for augmentation procedures.

CLINICAL RELEVANCE

Some off-track lesions might be misclassified as on-track lesions when the original commonly used static-based value of 83% is used as the glenoid track width.

Editorial Commentary: It Is Not the Size, But the Location of Hill-Sachs Lesion That Matters

The risk of a Hill-Sachs lesion (HSL) to engage the anterior glenoid rim depends on the location of the medial margin of the HSL relative to the anterior rim of the glenoid. The same-sized HSL can be engaging or nonengaging depending upon the size of the glenoid. In order to assess these bony lesions (bipolar lesion) together, the glenoid track concept has been introduced: an on-track lesion (stable) and an off-track lesion (unstable). Three-dimensional computed tomography (3D-CT) confirms that more medialized HSLs have larger volume, greater width, more surface area loss, and higher lesion angles (HS angle), and are more inferior in the humeral head. We know that medialization of the HSL is a definitive risk factor to make it off track, whereas the volume, surface area, and width are all subordinate risk factors dependent on the medialization. On the other hand, while we know very little about the orientation of the HSL, recent research shows a significant association between the medialization and orientation of the HSL. However, we do not know whether the orientation is an independent risk factor or dependent on the medialization. There are two things I emphasize when I look at a HSL: 1) do not look at the HSL alone, but look at the glenoid as well, and 2) the risk of the HSL depends on the location of the medial margin of the HSL relative to the glenoid, not on the volume, depth, or length.

Editorial Commentary: Remplissage Is Not Needed When Performing the Latarjet Procedure in the Setting of Off-Track Hill-Sachs Lesions: One of the Classics Continues to Get Better With Age (and Some Help From New Data)

The glenoid track paradigm has played a pivotal role in the development of a contemporary approach to shoulder stabilization surgery. A number of studies have validated the importance of bipolar bone loss in the pathogenesis of recurrent anterior shoulder instability and defined the limitations of soft tissue-based, arthroscopic surgical approaches. The glenoid track paradigm has also helped to clarify the indications for coracoid transfer procedures, although some question persists as to the necessity of addressing an "off-track" Hill-Sachs lesion with remplissage concurrently with the Latarjet procedure for large glenoid bone defects. The best available evidence would suggest that the Latarjet procedure can be expected to yield favorable clinical outcomes even in the setting of an off-track Hill-Sachs lesion, thereby obviating the necessity of concomitant remplissage for cases involving advanced degrees of bipolar bone loss.