An Age-Based Approach to Anterior Shoulder Instability in Patients Under 40 Years Old: Analysis of a US Population

Arthroscopic stabilization surgery for first-time anterior shoulder dislocations: a systematic review and meta-analysis

BACKGROUND

The optimal management of first-time anterior shoulder dislocations (FTASDs) remains controversial. Therefore, the purpose of this study was to assess the efficacy of arthroscopic stabilization surgery for FTASDs through a systematic review and meta-analysis of existing literature.

METHODS

MEDLINE, Embase, and Web of Science were searched from inception to December 18, 2022, for single-arm or comparative studies assessing FTASDs managed with arthroscopic stabilization surgery following first-time dislocation. Eligible comparative studies included studies assessing outcomes following immobilization for an FTASD, or arthroscopic stabilization following recurrent dislocations. Eligible levels of evidence were I to IV. Primary outcomes included rates of shoulder redislocations, cumulative shoulder instability, and subsequent shoulder stabilization surgery.

RESULTS

Thirty-four studies with 2222 shoulder dislocations were included. Of these, 5 studies (n = 408 shoulders) were randomized trials comparing immobilization to arthroscopic Bankart repair (ABR) after a first dislocation. Another 16 studies were nonrandomized comparative studies assessing arthroscopic Bankart repair following first-time dislocation (ABR-F) to either immobilization (studies = 8, n = 399 shoulders) or arthroscopic Bankart repair following recurrent dislocations (ABR-R) (studies = 8, n = 943 shoulder). Mean follow-up was 59.4 ± 39.2 months across all studies. Cumulative loss to follow-up was 4.7% (range, 0%-32.7%). A composite rate of pooled redislocation, cumulative instability, and reoperations across ABR-F studies was 6.8%, 11.2%, and 6.1%, respectively. Meta-analysis found statistically significant reductions in rates of redislocation (odds ratio [OR] 0.09, 95% confidence interval [CI] 0.04-0.3, P < .001), cumulative instability (OR 0.05, 95% CI 0.03-0.08, P < .001), and subsequent surgery (OR 0.08, 95% CI 0.04-0.15, P < .001) when comparing ABR-F to immobilization. Rates of cumulative instability (OR 0.32, 95% CI 0.22-0.47, P < .001) and subsequent surgery rates (OR 0.27, 95% CI 0.09-0.76, P = .01) were significantly reduced with ABR-F relative to ABR-R, with point estimate of effect favoring ABR-F for shoulder redislocation rates (OR 0.59, 95% CI 0.19-1.83, P = .36). Return to sport rates to preoperative levels or higher were 3.87 times higher following ABR-F compared to immobilization (95% CI 1.57-9.52, P < .001), with limited ABR-R studies reporting this outcome. The median fragility index of the 5 included randomized controlled trials (RCTs) was 2, meaning reversing only 2 outcome events rendered the trials' findings no longer statistically significant.

CONCLUSION

Arthroscopic stabilization surgery for FTASDs leads to lower rates of redislocations, cumulative instability, and subsequent stabilization surgery relative to immobilization or arthroscopic stabilization surgery following recurrence. Although a limited number of RCTs have been published on the subject matter to date, the strength of their conclusions is limited by a small sample size and statistically fragile results.

Minimal but potentially clinically relevant anteroinferior position of the humeral head following traumatic anterior shoulder dislocations: A 3D-CT analysis

In unstable shoulders, excessive anteroinferior position of the humeral head relative to the glenoid can lead to a dislocation. Measuring humeral head position could therefore be valuable in quantifying shoulder laxity. The aim of this study was to measure (1) position of the humeral head relative to the glenoid and (2) joint space thickness during passive motion in unstable shoulders caused by traumatic anterior dislocations and in contralateral uninjured shoulders. A prospective cross-sectional CT-study was performed in patients with unilateral anterior shoulder instability. Patients underwent CT scanning of both injured and uninjured side in supine position (0° abduction and 0° external rotation) and in 60°, 90°, and 120° of abduction with 90° of external rotation without an external load. Subsequently, 3D virtual models were created of the humerus and the scapula to create a glenoid coordinate system to identify poster-anterior, inferior-superior, and lateral-medial position of the humeral head relative to the glenoid. Joint space thickness was defined as the average distance between the subchondral bone surfaces of the humeral head and glenoid. Fifteen consecutive patients were included. In supine position, the humeral head was positioned more anteriorly (p = 0.004), inferiorly (p = 0.019), and laterally (p = 0.021) in the injured compared to the uninjured shoulder. No differences were observed in any of the other positions. A joint-space thickness map, showing the bone-to-bone distances, identified the Hill-Sachs lesion footprint on the glenoid surface in external rotation and abduction, but no differences on average joint space thickness were observed in any position.

Sutures, Screws, Buttons, and Anchors: A Review of Current Bone Graft Fixation Devices for Glenoid Bone Loss in the Unstable Shoulder

PURPOSE OF REVIEW

Anterior shoulder instability is associated with concomitant injury to several stabilizing structures of the shoulder, including glenoid bone loss. While instability is most common in young athletes and patients with predisposing conditions of hyperlaxity, recurrent shoulder instability can occur throughout various age ranges and may lead to longer term effects including pain and shoulder arthritis. Glenoid bone loss exceeding certain thresholds is generally treated by glenoid reconstruction via bone block augmentation to adequately stabilize the glenohumeral joint. These procedures increase the width of the articular surface on which the humeral head can translate before dislocation and, based on the procedure performed, provide a sling effect via the conjoined tendon, and increase tension to support the anterior capsule. The purpose of this review is to summarize the available literature regarding bone block fixation techniques.

RECENT DEVELOPMENTS

Various fixation techniques have been utilized to secure bone block transfers. Though screw fixation has traditionally been used for bone block fixation, suture buttons, suture anchors, and all-suture techniques have been utilized in attempts to avoid complications associated with the use of screws. Biomechanical studies report variable force-resistance, displacement, and mode of failure when comparing screw to suture button-based fixation of glenoid bone blocks. Clinical and radiographic studies have shown these novel suture-based techniques to be comparable, and in some cases advantageous, to traditional screw fixation techniques. While screw fixation has long been the standard of care in glenoid bone block procedures, it is associated with high complication rates, leading surgeons to endeavor toward new fixation techniques. In available biomechanical studies, screw fixation has consistently demonstrated high maximal load-to-failure and displacement with cyclic loading. Studies have reported similar clinical and radiographic outcomes in both screw and suture-based fixation methods, with evidence of reduced bone resorption with suture fixation. While suture button fixation is associated with a higher rate of recurrent instability, overall complication rates are low. Future research should address biomechanical shortcomings of suture-based fixation techniques and continue to assess long-term follow-up of patients treated with each fixation method.

Periostin Is a Biomarker for Anterior Shoulder Instability: Proteomic Analysis of Synovial Fluid

BACKGROUND

The incremental biological changes in the synovial microenvironment of the shoulder in acute and chronic instability that may contribute to joint degeneration are poorly understood. Proteomic analysis of synovial fluid in patients with shoulder instability may improve our understanding of proteins that are shed into shoulder synovial fluid after an injury.

HYPOTHESIS

Injury-specific factors such as the direction of instability and the severity of glenoid and humeral bone loss are associated with the proteome of synovial fluid in patients with shoulder instability.

STUDY DESIGN

Descriptive laboratory study.

METHODS

Synovial fluid lavage samples were compared between patients with anterior (n = 12) and posterior (n = 8) instability and those without instability (n = 5). Synovial proteins were identified with liquid chromatography-tandem mass spectrometry. Orthogonal validation of protein targets found to be significant on tandem mass spectrometry was performed in a separate set of prospective patients with Western blotting. Data were processed and analyzed, and P values were adjusted with the Benjamini-Hochberg method for multiple comparisons.

RESULTS

A total of 25 patients were included. Tandem mass spectrometry identified 720 protein groups in synovial fluid of patients with shoulder instability. There were 4 synovial proteins that were significantly expressed in patients with anterior instability relative to posterior instability: periostin (POSTN) (adjusted P value = .03; log fold change [logFc] = 4.7), transforming growth factor beta-induced protein ig-h3 (adjusted P value = .05; logFc = 1.7), collagen type VI alpha-3 chain (adjusted P value = .04; logFc = 2.6), and coagulation factor V (adjusted P value = .04; logFc = -3.3). Among these targets, POSTN showed a moderate correlation with the Hill-Sachs lesion size (r = 0.7). Prospective validation with Western blotting confirmed a significantly higher level of POSTN in synovial fluid of patients with anterior instability (P = .00025; logFc = 5.1).

CONCLUSION

Proteomic analysis enriched our understanding of proteins that were secreted into shoulder synovial fluid of patients with shoulder instability. The identification of POSTN, a proinflammatory catabolic protein involved with tissue remodeling and repair, as a significant target in anterior shoulder instability is a novel finding. Therefore, further study is warranted to determine the role that POSTN may play in the progression of bone loss and posttraumatic osteoarthritis.

CLINICAL RELEVANCE

Proteomic analysis of synovial fluid in patients with shoulder instability improved our understanding of this abnormality after an injury.

Current Evidence Regarding Shoulder Instability in the Paediatric and Adolescent Population

Paediatric and adolescent shoulder instability is caused by a unique combination of traumatic factors, ligamentous laxity, and pattern of muscle contractility. The multifactorial nature of its aetiology makes interpretation of the literature difficult as nomenclature is also highly variable. The purpose of this review is to summarize the existing literature and shed light on the nuances of paediatric and adolescent shoulder instability. The epidemiology, clinical features, imaging, and management of all forms of paediatric shoulder instability are presented. The main findings of this review are that structural abnormalities following a dislocation are uncommon in pre-pubertal paediatric patients. Young post-pubertal adolescents are at the highest risk of failure of non-operative management in the setting of traumatic instability with structural abnormality, and early stabilisation should be considered for these patients. Remplissage and the Latarjet procedure are safe treatment options for adolescents at high risk of recurrence, but the side-effect profile should be carefully considered. Patients who suffer from instability due to generalized ligamentous laxity benefit from a structured, long-term physiotherapy regimen, with surgery in the form of arthroscopic plication as a viable last resort. Those who suffer from a predominantly muscle patterning pathology do not benefit from surgery and require focus on regaining neuromuscular control.

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.

Global variations in treatment and outcomes reported for anterior shoulder instability: a systematic review of the literature

Background

Anterior shoulder instability is a common problem around the world, with a high risk for recurrence following the index dislocation. Surgical stabilization is commonly indicated for persistent instability, particularly in patients at high risk for recurrence, to minimize the risk of further labral injury and glenoid bone loss. However, there is little known about global geographic differences in the surgical management of anterior shoulder instability. As such, the purpose of this study was to evaluate and systematically review regional differences in the surgical treatment of anterior shoulder instability, particularly the indications for and outcomes from bony stabilization procedures compared to soft tissue procedures.

Methods

A systematic review, in accordance with the 2020 Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines, was performed. Inclusion criteria consisted of level I and II evidence studies evaluating indications, techniques, and outcomes following operative management of anterior shoulder instability published from January 2000 to September 2021. Studies meeting inclusion criteria were grouped into four global regions (Asia, Europe, North America, South America) based on primary study location. Patient demographics, procedural details, patient reported outcomes, and complications (recurrence and reoperation rates) were compared between regions.

Results

Sixty (n = 60) studies (5480 patients) were identified. Eighty-six percent of all patients were male, with a mean age of 26.7 years. There was no difference in mean patient age, though patients undergoing bony stabilization procedures were older than those undergoing soft-tissue stabilization procedures (P = .0002) in all regions. The proportion of bony versus soft-tissue procedure groups did not differ significantly among regions. The indications for bony stabilization procedures varied significantly. Mean final follow-up was 3.5 years. Recurrent instability was 5.0% and did not vary across regions. However, recurrent instability occurred more frequently following soft-tissue compared to bony stabilization procedures (P = .017). South American studies utilized fewer anchors during soft tissue stabilization (P < .0001) and reported a higher reoperation rate compared to other regions (P = .009).

Conclusion

There is global variation in the reporting of outcomes following surgery for anterior shoulder instability. The proportion of bony and soft-tissue procedures is similar, irrespective of geographic region. Recurrent instability does not vary by region but occurs more frequently following soft-tissue compared to bony stabilization procedures. There are a number of potential medical and nonmedical factors that may affect global variation in the surgical treatment of anterior shoulder instability.

Incidence of bony Bankart lesions in Sweden: a study of 790 cases from the Swedish fracture register

BACKGROUND

A bony Bankart lesion directly affects the stability of the shoulder by reducing the glenoid joint-contact area. The aim of this study was to report on the epidemiological data relating to bony Bankart lesions in Sweden using the Swedish fracture register. The purpose is to evaluate age and sex distribution in the population with bony Bankart lesions, its impact on treatment strategy and further to analyse patient-reported outcomes.

METHODS

This was an epidemiological descriptive study. The inclusion criteria were all patients with a unilateral bony Bankart lesion registered between April 2012 and April 2019. The patients' specific data (age, sex, type and time of injury, treatment option and patient-reported outcomes) were extracted from the Swedish fracture register database.

RESULTS

A total of 790 unilateral bony Bankart fractures were identified. The majority of the patients were male (58.7%). The median age for all patients at the time of injury was 57 years. Females had a higher median age of 66 years, compared with males, 51 years. Most of the bony Bankart lesions, 662 (91.8%), were registered as a low-energy trauma. More than two-thirds of all treatment registered cases, 509/734 patients (69.3%), were treated non-surgically, 225 (30.7%) were treated surgically, while, in 17 patients (7.5% of all surgically treated patients), the treatment was changed from non-surgical to surgical due to recurrent instability. Surgical treatment was chosen for 149 (35%) of the males and for 76 (25%) of the females. Patient quality of life decreased slightly in both surgically and non-surgically treated groups 1 year after bony Bankart injury.

CONCLUSION

This national register-based study provides detailed information on the epidemiology, choice of treatment and patient-reported outcomes in a large cohort of bony Bankart lesions. Most bony Bankart lesions affected males between 40 and 75 years after low-energy falls and non-surgical treatment dominated.

Artificial Intelligence Can Define and Predict the "Optimal Observed Outcome" After Anterior Shoulder Instability Surgery: An Analysis of 200 Patients With 11-Year Mean Follow-Up

Purpose

The purpose of this study was to use unsupervised machine learning clustering to define the "optimal observed outcome" after surgery for anterior shoulder instability (ASI) and to identify predictors for achieving it.

Methods

Medical records, images, and operative reports were reviewed for patients <40 years old undergoing surgery for ASI. Four unsupervised machine learning clustering algorithms partitioned subjects into "optimal observed outcome" or "suboptimal outcome" based on combinations of actually observed outcomes. Demographic, clinical, and treatment variables were compared between groups using descriptive statistics and Kaplan-Meier survival curves. Variables were assessed for prognostic value through multivariate stepwise logistic regression.

Results

Two hundred patients with a mean follow-up of 11 years were included. Of these, 146 (64%) obtained the "optimal observed outcome," characterized by decreased: postoperative pain (23% vs 52%; P < 0.001), recurrent instability (12% vs 41%; P < 0.001), revision surgery (10% vs 24%; P = 0.015), osteoarthritis (OA) (5% vs 19%; P = 0.005), and restricted motion (161° vs 168°; P = 0.001). Forty-one percent of patients had a "perfect outcome," defined as ideal performance across all outcomes. Time from initial instability to presentation (odds ratio [OR] = 0.96; 95% confidence interval [CI], 0.92-0.98; P = 0.006) and habitual/voluntary instability (OR = 0.17; 95% CI, 0.04-0.77; P = 0.020) were negative predictors of achieving the "optimal observed outcome." A predilection toward subluxations rather than dislocations before surgery (OR = 1.30; 95% CI, 1.02-1.65; P = 0.030) was a positive predictor. Type of surgery performed was not a significant predictor.

Conclusion

After surgery for ASI, 64% of patients achieved the "optimal observed outcome" defined as minimal postoperative pain, no recurrent instability or OA, low revision surgery rates, and increased range of motion, of whom only 41% achieved a "perfect outcome." Positive predictors were shorter time to presentation and predilection toward preoperative subluxations over dislocations.

Level of Evidence

Retrospective cohort, level IV.

Patients Aged >50 Years With Anterior Shoulder Instability Have a Decreased Risk of Recurrent Dislocation After Operative Treatment Compared With Non-Operative Treatment

Purpose

To compare the clinical outcomes of operative and nonoperative management, identify risk factors for recurrent instability, and identify risk factors for progression to surgery after failed nonoperative management for patients with first-time anterior shoulder dislocation after the age of 50 years.

Methods

An established geographic medical record system was used to identify patients who experienced a first-time anterior shoulder dislocation after the age of 50 years. Patient medical records were reviewed to identify treatment decisions and outcomes of interest, including rates of frozen shoulder and nerve palsy, progression to osteoarthritis, recurrent instability, and progression to surgery. Outcomes were evaluated using Chi-square tests and survivorship curves were generated using Kaplan-Meier methods. A Cox model was developed to evaluate for potential risk factors of recurrent instability and progression to surgery after an initial trail of at least 3 months of nonoperative treatment.

Results

179 patients were included with a mean follow-up of 11 years. 14% (n = 26) underwent early surgery within 3 months and 86% (n = 153) were initially treated nonoperatively. Mean age (59 years), was similar for both groups, but those that underwent early surgery had an increased rate of full-thickness rotator cuff tears (82% vs 55%; P = .01), labral tears (24% vs 8.0%; P = .01), and humeral head fracture (23% vs 8.5%; P = .03). When comparing the early surgery group to the nonoperative group, there were similar rates of persistent moderate-severe pain (19% vs 17%; P = .78) and frozen shoulder (8 vs 9%, respectively; P = .87) at final follow-up. Although nerve palsy (19% vs 8%; P = .08) and progression to osteoarthritis (20% vs 14%; P = .40) were more common in surgical patients, they experienced lower rates of recurrent instability after surgical intervention (0% vs 15%; P = .03) compared to nonoperatively treated patients. Increasing number of instability events prior to presentation was the greatest risk factor for recurrent instability (HR 232; P < .01). Fourteen percent (n = 21) failed initial nonoperative treatment and proceeded to surgical intervention at an average of 4.6 years after the initial instability event, and the greatest risk factors for progression to surgery were recurrent instability (HR 3.41; P < .01).

Conclusions

Although the majority of patients >50 years that experience ASI are treated nonoperatively, those that require surgery tend to have more significant injury pathology, a lower risk of recurrent instability after surgery, but a higher progression to osteoarthritis compared to patients that do not require surgical intervention. There was no difference in pain severity at final follow-up, rates of frozen shoulder or nerve palsy between patients who underwent initial nonoperative treatment after instability and those who underwent surgery. A history of multiple instability episodes prior to presentation was the greatest predictor of recurrent instability and failure of nonoperative treatment and progression to surgery.

Level of Evidence

Level III, retrospective cohort study.

Shoulder Anteroinferior Glenoid Labrum Reconstruction With the Long Head of the Biceps Tendon Restores Glenohumeral Stability: A Cadaveric Biomechanical Study

PURPOSE

The purpose of this cadaveric study was to determine feasibility and assess biomechanical stability of glenoid labral reconstruction utilizing the long head of the biceps tendon (LHBT) as a local autograft for labral deficient shoulders.

METHODS

Ten cadaveric shoulders underwent resection of all soft tissue structures except the labrum and LHBT. The scapula and humerus were separately attached to a custom shoulder testing apparatus allowing for 22.5 N of compressive isotonic force across the joint. An Instron (Electroplus 1000) measured the peak force (N) as the humeral head was translated over the anteroinferior glenoid rim through 10 cycles. Shoulders were tested in 3 separate scenarios: intact labrum, resected labrum from 3- to 6-o'clock (for a right shoulder), and labral reconstruction with the LHBT. Reconstruction was performed by performing LHBT tenotomy at the level of the pectoralis major insertion. The proximal LHBT tendon, left attached to the supraglenoid tubercle, was then attached to the anteroinferior glenoid rim with suture anchors.

RESULTS

Mean (SD) length of the LHBT was 76.1 (12.9 mm) and the diameter was 5.9 (1.6) mm. Peak force for intact labrum was significantly greater than the deficient labrum state (14.06 vs 11.78 N; P = .012). Peak force for labral reconstruction (16.67 N) was significantly greater than both intact and deficient labral states (P < .001 and P = .011, respectively). In all specimens, the length for the LHBT to the pectoralis major insertion was sufficient for reconstruction of the labrum to the 6-o'clock position.

CONCLUSIONS

Glenoid labrum reconstruction with the LHBT is a feasible option to restore glenohumeral stability, with peak force to displacement significantly greater than the labral-intact and labral-deficient states.

CLINICAL RELEVANCE

This reconstruction may be an option for augmentation in the labral-deficient shoulder.

Clinical and Radiological Outcomes in Patients With Anterior Shoulder Instability and Glenoid Bone Loss after Arthroscopic Free Bone Block Combined With Dynamic Anterior Stabilization

BACKGROUND

As an alternative to the Latarjet procedure, the arthroscopic free bone block (FBB) procedure combined with dynamic anterior stabilization (DAS) has been recently proposed to provide both glenoid augmentation and a tendon sling effect for treating anterior shoulder instability (ASI) with glenoid bone loss.

PURPOSE

To evaluate the clinical and radiological outcomes of FBB-DAS for ASI with glenoid bone loss.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

Patients who underwent arthroscopic FBB-DAS for ASI with >15% glenoid bone loss between February 2017 and March 2020 were screened and enrolled in this study. Clinical outcome measures were assessed preoperatively and at a minimum 2-year follow-up, including recurrence, complications, shoulder functional scores, range of motion, and return to sports. Postoperative computed tomography and magnetic resonance imaging were also performed.

RESULTS

Of a total of 65 patients with a mean follow-up of 46.1 ± 13.1 months, no patients experienced a recurrent dislocation or subluxation postoperatively, while 2 had a positive anterior apprehension test (3.1%). Additionally, 2 patients (3.1%) experienced complications of hematoma and shoulder stiffness, respectively. The mean visual analog scale score, American Shoulder and Elbow Surgeons score, Rowe score, and Oxford Shoulder Instability Score all improved significantly from 3.2 ± 2.4, 75.0 ± 18.9, 43.6 ± 27.3, and 33.8 ± 9.0 preoperatively to 1.3 ± 0.8, 95.1 ± 8.0, 95.5 ± 7.8, and 14.8 ± 3.5 at final follow-up, respectively (all P < .001). No difference was detected in range of motion except for 8.1° and 7.5° external rotation limitations in adduction and abduction, respectively. There were 62 patients (95.4%) who returned to sports, and 54 patients (83.1%) returned to the preinjury level. The transferred biceps tendon was intact in all 59 patients who completed radiological examination at the latest follow-up. Good bone healing was achieved in 98.3% of patients, and the glenoid bone defect decreased from 18.1% to 4.9%. Osseous and labral glenoids were significantly enlarged in width and depth on the latest magnetic resonance imaging (all P < .001).

CONCLUSION

Arthroscopic FBB-DAS provided satisfactory clinical and radiological outcomes for ASI with glenoid bone loss. Despite slight external rotation restrictions, it achieved low recurrence and complication rates, excellent shoulder functional scores, a high return-to-sports rate, and favorable graft healing and remodeling.

Natural History of First-Time Anterior Shoulder Dislocation in Patients Older Than 50 Years: A Study of 179 Patients With a Mean Follow-up of 11 Years

Background

There is a dearth of knowledge on anterior shoulder instability in older patients.

Purpose/Hypothesis

The purposes of this study were to describe the incidence and epidemiology, injury characteristics, and treatment and outcomes in patients ≥50 years old with first-time anterior shoulder instability. We also describe the historical trends in diagnosis and treatment. It was hypothesized that the rates of obtaining a magnetic resonance imaging (MRI) scan and surgical intervention have increased over the past 20 years.

Study Design

Descriptive epidemiology study.

Methods

An established geographic database was used to identify 179 patients older than 50 years who experienced new onset anterior shoulder instability between 1994 and 2016. Medical records were reviewed to obtain patient characteristics, imaging characteristics, and surgical treatment and outcomes, including recurrent instability. Comparative analysis was performed to identify differences between age groups. Mean follow-up time was 11 years.

Results

The incidence of first-time anterior shoulder dislocation in our study population was 28.8 per 100,000 person-years, which is higher than previously reported. Full-thickness rotator cuff tears were found in 62% of the 66 patients who underwent MRI scans. Of all patients, 26% progressed to surgery at a mean time of 1.6 years after injury; 57% of all surgical procedures involved a rotator cuff repair, and 17% included anterior labral repair. All patients who underwent a labral repair also underwent concomitant rotator cuff repair. The rate of recurrent instability for the cohort was 15% at a median of 176 days after the initial instability event. There were no instances of recurrent instability after operative intervention. At an average of 7.5 years after the initial instability event, 14% of patients developed radiographic progression of glenohumeral arthritis. The rate of surgical intervention within 1 year of initial dislocation increased from 5.1% in 1994 to 1999 to 52% in 2015 to 2016.

Conclusion

The incidence of first-time anterior shoulder instability in patients aged ≥50 years was 28.8 per 100,000 person-years. Full-thickness rotator cuff tears (62%) were the most common condition associated with anterior shoulder instability, followed by Hill-Sachs lesions (56%). The rate of recurrent instability for the entire cohort was 15%, with no instances of recurrent instability after operative intervention.

Bankart Repair With Remplissage Restores Better Shoulder Stability Than Bankart Repair Alone, and Medial or Two Remplissage Anchors Increase Stability but Decrease Range of Motion: A Finite Element Analysis

PURPOSE

To investigate the effects of the number and location of anchors for remplissage on postoperative glenohumeral biomechanics.

METHODS

A biomechanical study was conducted involving finite element model constructed based on data from the intact glenohumeral joint. Seven models were established, including a normal model, a model of Bankart lesion combined with "off-track" Hill-Sachs lesion, a model of Bankart repair alone, and 4 models of Bankart repair with remplissage based on different remplissage anchor numbers and locations. The effects of the number and location of the remplissage anchors on glenohumeral stability were studied through calculation and comparison of (1) the stress and its distribution on the joint capsule, cartilage, labrum and anchors as well as (2) the displacement of the humeral head.

RESULTS

Finite element analysis demonstrated that contact stress on the glenohumeral cartilage decreased when medial or 2 anchors were used and was minimized in the combined repair model with 2 medial anchors. The stress on remplissage anchors was greater when the anchors were placed medially. The humeral head displacement was maximized in the combined lesion model. The combined repair models with 2 medially placed anchors showed the largest slope on the force-displacement curve, indicating the largest strain on the humeral head.

CONCLUSIONS

Based on a finite element analysis, Bankart repair with remplissage restored better shoulder stability compared with Bankart repair alone in the treatment of anterior shoulder instability involving Bankart lesion combined with "off-track" Hill-Sachs lesion. When the anchor for remplissage was medially placed or 2 anchors were used, the stability of the glenohumeral joint increased but with a loss of range of motion.

CLINICAL RELEVANCE

The results of this study will assist in choosing the number and location of anchors for remplissage during shoulder stabilization surgery although with some limitations.

Anteroinferior Glenoid Rim Fractures Are a Relatively Common Finding in Shoulder Instability Patients Aged 50 Years or Older but May Not Portend a Worse Prognosis

Purpose

To investigate the incidence of anteroinferior glenoid rim fractures (AGRFs) after anterior shoulder instability (ASI) in patients aged 50 years or older, identify risk factors for surgical intervention for AGRFs, compare initial treatment strategies, and compare clinical outcomes of patients with and without associated AGRFs.

Methods

An established geographic medical record system was used to identify patients aged 50 years or older with ASI between 1994 and 2016. Patients with radiographic evidence of AGRFs were identified and matched 1:1 to patients without AGRFs. Outcome measures included recurrent instability, recurrent pain events, conversion to arthroplasty, and osteoarthritis graded with the Samilson-Prieto classification for post-instability arthritis.

Results

Overall, 177 patients were identified, with a mean follow-up period of 10.8 years. Of these patients, 41 (23.2%) had AGRFs and were matched to 41 control patients without AGRFs. The average age was 58.6 and 58.2 years for the AGRF and control groups, respectively. Rates of surgical intervention (27% vs 49%), recurrent instability (12% vs 20%), progression of osteoarthritis (34% vs 39%), and conversion to arthroplasty (2% vs 5%) were similar between AGRF patients and controls. For patients with AGRFs, increased bone fragment size (odds ratio, 1.1) and increased body mass index (odds ratio, 1.2) correlated with an increased risk of surgery. The cutoff value for an increased risk of surgery in patients with AGRFs was a fragment size 33% of the glenoid width or greater.

Conclusions

Of patients aged 50 years or older at presentation of ASI, 23.2% presented with an associated AGRF. A fragment size 33% of the glenoid width or greater and a higher patient body mass index were significant factors for surgical intervention; however, most patients did not require surgery and still showed acceptable clinical outcomes, and the most common reason for surgical intervention was a rotator cuff tear. Overall, the presence of an AGRF did not portend a worse prognosis as treatment strategies and long-term outcomes including recurrent instability, progression of osteoarthritis, and conversion to arthroplasty were similar to those in patients without AGRFs.

Level of Evidence

Level III, retrospective comparative study.

Arthroscopic Biceps Transfer to the Glenoid With Bankart Repair Grants Satisfactory 2-Year Results for Recurrent Anteroinferior Glenohumeral Instability in Subcritical Bone Loss

PURPOSE

To evaluate the short-term outcomes of the arthroscopic dynamic anterior stabilization (DAS), which is a transfer of the intra-articular portion of the long head biceps through the subscapularis split and fixation on the anterior glenoid, combined with a Bankart repair.

METHODS

A retrospective evaluation was performed of DAS and a minimum of 2-year follow-up. Inclusion criteria were the presence of anteroinferior instability, a positive apprehension test at 90° of abduction and external rotation, and subcritical glenoid bone loss (less than 20%). Exclusion criteria were severe (≥20%) glenoid bone loss, presence of biceps lesions or rupture (spontaneous or biceps tenotomy), pre-existing glenohumeral osteoarthritis, multidirectional or voluntary instability, previous arthroscopic stabilization procedure, and epilepsy. Outcomes included the Rowe score, range of motion (ROM), and recurrence.

RESULTS

Twenty-three patients were treated with DAS and arthroscopic Bankart repair during the study period. One person was lost to follow-up, leaving 22 patients available at last follow-up. Those 22 patients had an average age of 31.9 ± 12.3 years (range, 18-68) and were evaluated at an average follow-up of 3.2 ± 0.7 years (range, 1.2-4.2). The Rowe score increased from 36.1 ± 16.2 (range, 10-70) preoperatively to 89.8 ± 20.1 (range, 30-100) postoperatively (P < .001) with almost all patients (90.9%) improving their score beyond the minimal clinically important difference of 9.7 points. Postoperatively, ROM was maintained. Three patients (13.6%) analyzed at final follow-up demonstrated recurrence, one was successfully treated conservatively, but two revised with a Latarjet. No postoperative Popeye deformity, biceps cramping, or other complication were reported.

CONCLUSIONS

The DAS procedure may be an option for augmentation of a Bankart repair in patients with anterior shoulder instability and subcritical bone loss. ROM is maintained without evidence of postoperative Popeye deformity or biceps cramping.

LEVEL OF EVIDENCE

Level IV, retrospective study.

Failure and Complication Rates in Common Sports and Arthroscopic Procedures: Reality Check

Expectations following sports medicine and arthroscopic procedures have been elevated because of captivating modern-day media coverage of high-profile athletic injuries, surgery, and rapid return to sports. Unfortunately, this general perception may be misleading, and orthopedic sports medicine physicians must be aware of the harsh reality of the trials and tribulations associated with the subspecialty. The purpose of this review article is to provide an updated brief overview of the complications and failure rates associated with common arthroscopic procedures including rotator cuff repair, biceps tenodesis, Bankart procedure, Latarjet procedure, anterior cruciate ligament reconstruction, anterior cruciate ligament repair, meniscal repair, tibial tubercle osteotomy, and medial patellofemoral ligament reconstruction. Highlighting the complications is the first step toward early recognition, enhancing preventative measures, and successful management.

Nonoperative management of anterior shoulder instability can result in high rates of recurrent instability and pain at long-term follow-up

BACKGROUND

Data on the long-term outcomes of nonoperative treatment of anterior shoulder instability are lacking, particularly for the US population. The purpose was to (1) describe the characteristics of patients with anterior shoulder instability treated nonoperatively, (2) assess the long-term outcomes of nonoperative management in a US population, and (3) identify risk factors for poor outcomes following nonoperative management.

METHODS

A geographic cohort of >500,000 subjects was used to identify patients treated nonoperatively for anterior shoulder instability. Only patients aged <40 years at the time of initial instability with minimum 10-year follow-up were included. Medical records were reviewed to obtain demographic characteristics, physical examination findings, clinical history data, imaging results, treatment details, and clinical and/or radiographic progression. Recurrent pain, recurrent instability, and the development of symptomatic osteoarthritis (OA) were the primary outcomes evaluated.

RESULTS

The study included 254 patients (73% male) with a median age of 19 years (range, 16-26 years) at the time of initial instability. At median 17-year follow-up, 37.5% experienced recurrent instability, 58.4% had recurrent pain, and 12.2% had symptomatic OA development. Factors associated with recurrent pain at final follow-up were multiple instability events prior to presentation (hazard ratio [HR], 2.43; P < .01) and increased pain at the initial visit (HRs of 0.79 for mild, 1.74 for moderate, and 1.39 for severe; P < .01); patients with multiple instability events prior to presentation also had an increased risk of recurrence (P < .01). Factors increasing the risk of the development of symptomatic OA included increased pain at the initial visit (P = .05), seizure disorder (HR, 27.01; P < .01), and smoking (HR, 5.15; P < .01).

CONCLUSIONS

At long-term follow-up of 17 years, a high rate of poor outcomes was observed following nonoperative management of anterior shoulder instability. Overall, 37.5% of patients experienced recurrent shoulder instability, 58.4% had recurrent shoulder pain, and 12.2% had symptomatic OA development. Risk factors associated with adverse clinical outcomes included increased pain at the initial visit, recurrent instability prior to presentation, seizure disorder, and smoking.

Anterior Shoulder Instability in Throwers and Overhead Athletes: Long-term Outcomes in a Geographic Cohort

BACKGROUND

Athletes of all sports often have shoulder instability, most commonly as anterior shoulder instability (ASI). For overhead athletes (OHAs) and those participating in throwing sports, clinical and surgical decision making can be difficult owing to a lack of long-term outcome studies in this population of athletes.

PURPOSE/HYPOTHESIS

To report presentation characteristics, pathology, treatment strategies, and outcomes of ASI in OHAs and throwers in a geographic cohort. We hypothesized that OHAs and throwers would have similar presenting characteristics, management strategies, and clinical outcomes but lower rates of return to play (RTP) when compared with non-OHAs (NOHAs) and nonthrowers, respectively.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

An established geographic medical record system was used to identify OHAs diagnosed with ASI in the dominant shoulder. An overall 57 OHAs with ASI were matched 1:2 with 114 NOHAs with ASI. Of the OHAs, 40 were throwers. Sports considered overhead were volleyball, swimming, racquet sports, baseball, and softball, while baseball and softball composed the thrower subgroup. Records were reviewed for patient characteristics, type of sport, imaging findings, treatment strategies, and surgical details. Patients were contacted to collect Western Ontario Shoulder Instability index (WOSI) scores and RTP data. Statistical analysis compared throwers with nonthrowers and OHAs with NOHAs.

RESULTS

Four patients, 3 NOHAs and 1 thrower, were lost to follow-up at 6 months. Clinical follow-up for the remaining 167 patients (98%) was 11.9 ± 7.2 years (mean ± SD). Of the 171 patients included, an overall 41 (36%) NOHAs, 29 (51%) OHAs, and 22 (55%) throwers were able to be contacted for WOSI scores and RTP data. OHAs were more likely to initially present with subluxations (56%; P = .030). NOHAs were more likely to have dislocations (80%; P = .018). The number of instability events at presentation was similar. OHAs were more likely to undergo initial operative management. Differences in rates of recurrent instability were not significant after initial nonoperative management (NOHAs, 37.1% vs OHAs, 28.6% [P = .331] and throwers, 21.2% [P = .094]) and surgery (NOHAs, 20.5% vs OHAs, 13.0% [P = .516] and throwers, 9.1% [P = .662]). Rates of revision surgery were similar (NOHAs, 18.0% vs OHAs, 8.7% [P = .464] and throwers, 18.2% [P > .999]). RTP rates were 80.5% in NOHAs, as compared with 71.4% in OHAs (P = .381) and 63.6% in throwers (P = .143). Median WOSI scores were 40 for NOHAs, as compared with 28 in OHAs (P = .425) and 28 in throwers (P = .615).

CONCLUSION

In a 1:2 matched comparison of general population athletes, throwers and OHAs were more likely to have more subtle instability, as evidenced by higher rates of subluxations rather than frank dislocations, when compared with NOHAs. Despite differences in presentation and the unique sport demands of OHAs, rates of recurrent instability and revision surgery were similar across groups. Similar outcomes in terms of RTP, level of RTP, and WOSI scores were achieved for OHAs and NOHAs, but these results must be interpreted with caution given the limited sample size.

The Nonoperative Instability Severity Index Score: Is It Predictive in a Larger Shoulder Instability Population at Long-Term Follow-Up?

PURPOSE

To evaluate the effect of the Nonoperative Instability Severity Index Score (NISIS) criteria on an established US-geographic population-based cohort of patients with anterior shoulder instability.

METHODS

An established geographically based medical record system was used to identify patients <40 years of age with anterior shoulder instability between 1994 and 2016. Medical records were reviewed to obtain patient demographics and instability characteristics. Patient-specific risk factors were individually incorporated into the 10-point NISIS criteria: age (>15 years), bone loss, type of instability (dislocation vs subluxation), type of sport (collision vs noncollision), male sex, and dominant arm involvement. High risk was considered a score of ≥7 points and low risk as <7 points. Failure was defined as either progression to surgery or recurrent instability diagnosed by a consulting physician at any point after initial consultation.

RESULTS

The study population consisted of 405 patients with a mean follow-up time of 9.6 ± 5.9 years. Failure was defined as recurrent instability or progression to surgery, and the overall failure rate was 52.8% (214/405). The rate of recurrent instability after initial consultation was 34.6% (140/405), and the rate of conversion to surgery was 37.8% (153/405). A total of 264 (65.2%) patients were considered low risk (NISIS < 7), and 141 (34.8%) patients were considered high risk (NISIS ≥ 7). Patients in the high-risk group were more likely to fail nonoperative management than those in the low-risk group (60.3% vs 48.9%; P = .028).

CONCLUSIONS

The NISIS has been proposed as a potentially useful tool in clinical decision-making regarding the appropriate use of nonoperative treatment in scholastic athletes. When applied to an established US-geographic population-based cohort consisting of competitive and recreational athletes under the age of 40 with longer-term follow-up, the NISIS high-risk cutoff was able to predict overall failure with 60.3% accuracy.

LEVEL OF EVIDENCE

III, retrospective observation trial.

Understanding Anterior Shoulder Instability Through Machine Learning: New Models That Predict Recurrence, Progression to Surgery, and Development of Arthritis

Background

Management of anterior shoulder instability (ASI) aims to reduce risk of future recurrence and prevent complications via nonoperative and surgical management. Machine learning may be able to reliably provide predictions to improve decision making for this condition.

Purpose

To develop and internally validate a machine-learning model to predict the following outcomes after ASI: (1) recurrent instability, (2) progression to surgery, and (3) the development of symptomatic osteoarthritis (OA) over long-term follow-up.

Study Design

Cohort study (prognosis); Level of evidence, 2.

Methods

An established geographic database of >500,000 patients was used to identify 654 patients aged <40 years with an initial diagnosis of ASI between 1994 and 2016; the mean follow-up was 11.1 years. Medical records were reviewed to obtain patient information, and models were generated to predict the outcomes of interest. Five candidate algorithms were trained in the development of each of the models, as well as an additional ensemble of the algorithms. Performance of the algorithms was assessed using discrimination, calibration, and decision curve analysis.

Results

Of the 654 included patients, 443 (67.7%) experienced multiple instability events, 228 (34.9%) underwent surgery, and 39 (5.9%) developed symptomatic OA. The ensemble gradient-boosted machines achieved the best performances based on discrimination (via area under the receiver operating characteristic curve [AUC]: AUC_recurrence = 0.86), AUC_surgery = 0.76, AUC_OA = 0.78), calibration, decision curve analysis, and Brier score (Brier_recurrence = 0.138, Brier_surgery = 0.185, Brier_OA = 0.05). For demonstration purposes, models were integrated into a single web-based open-access application able to provide predictions and explanations for practitioners and researchers.

Conclusion

After identification of key features, including time from initial instability, age at initial instability, sports involvement, and radiographic findings, machine-learning models were developed that effectively and reliably predicted recurrent instability, progression to surgery, and the development of OA in patients with ASI. After careful external validation, these models can be incorporated into open-access digital applications to inform patients, clinicians, and researchers regarding quantifiable risks of relevant outcomes in the clinic.

Relationship Between Age at Initial Shoulder Instability and Overall Outcomes After Arthroscopic Bankart Repair: Mean 6-Year Follow-up

Background:

Age at surgery plays a crucial role in the frequency of recurrent shoulder instability. However, there are few studies that evaluate the relationship between age at initial shoulder instability and overall outcomes after stabilization surgery.

Purpose:

To compare clinical outcomes and structural changes after arthroscopic Bankart repair in patients who experienced initial shoulder instability during adolescence versus those with later onset instability.

Study Design:

Cohort study; Level of evidence, 3.

Methods:

This study included patients who underwent arthroscopic Bankart repair at a single institution between 2007 and 2017. Comparisons were made between patients who experienced initial shoulder instability during adolescence (age 13-19 years; group A) and those with later onset instability (age 20-35 years; group B). Clinical outcomes (recurrence rate, postoperative pain, functional scores, active range of motion, and return to sports) and structural changes demonstrated by magnetic resonance imaging (MRI) were evaluated at minimum 2-year follow-up. In addition, functional outcomes within each group were compared between the patients with and without postoperative recurrence.

Results:

A total of 58 patients were included (24 patients in group A and 34 patients in group B). The mean follow-up was 72.1 months. Group A demonstrated a significantly higher recurrence rate than group B (41.7% vs 11.8%, respectively; P = .009; risk ratio, 5.36 [95% CI, 1.43-20.09]) as well as significantly lower Rowe (76.9 ± 20.1 vs 88.7 ± 13.2, respectively; P = .01) and Constant-Murley scores (92.2 ± 7.6 vs 96.3 ± 4.2, respectively; P = .01). Postoperative MRI revealed no significant structural differences between the groups regarding the glenoid labrum, glenohumeral cartilage, or osseous reaction around the implanted anchors. In group A, patients with recurrence had less satisfaction regarding postoperative sports level than those without recurrence, whereas in group B, patients with recurrence had more postoperative pain and functional impairment compared with those without recurrence.

Conclusion:

Initial shoulder instability during adolescence was associated with a higher recurrence rate and lower functional scores after arthroscopic Bankart repair compared with later onset instability, although no significant structural differences were found between the groups on MRI at a mean 6-year follow-up.

The financial burden associated with multiple shoulder dislocations and the potential cost savings of surgical stabilization

Introduction

Shoulder dislocation is a costly problem and can have a high risk for recurrent instability after initial dislocation based on well-defined patient characteristics. Patients with recurrent instability can be treated with shoulder stabilizing procedures. Although more costly, surgery may decrease the overall health care burden of managing a patient with multiple shoulder dislocations nonoperatively.

Methods

We performed a retrospective chart review of all patients who presented to the emergency department (ED) with a diagnosis of a shoulder dislocation at a level 1 academic trauma center during the year 2016. Patient information regarding the current dislocation episode, previous dislocations, shoulder surgeries, and postreduction follow-up was gathered. These data were then used to determine the average cost of an ED presentation for a shoulder dislocation episode as obtained from the hospital finance department. The average cost of shoulder stabilization surgery was used to conduct a cost-benefit analysis of operative vs. nonoperative management.

Results

Data were collected on 104 individuals who presented to the ED with shoulder dislocations. Of these, 65 were primary dislocations and 39 were recurrent dislocations. Twelve patients underwent shoulder stabilization surgery after their ED presentation. The average cost to the institution for an ED visit requiring the closed reduction of a shoulder dislocation was $2207 ($973.21 without sedation and $3744 with conscious sedation). The average cost of a shoulder stabilization procedure performed at this same institution was $7807.

Discussion and conclusion

Although shoulder stabilization has a higher cost on the front end, this intervention results in cost savings if it prevents 2-3 future shoulder dislocations resulting in ED visits. These findings suggest that, for patients with a high risk for recurrent instability, not only would stabilization surgery help prevent subsequent dislocation events but would also minimize health care costs.