Incidence of Posterior Shoulder Instability in the United States Military: Demographic Considerations From a High-Risk Population

SECEC Didier Patte Prize 2023: the ABC classification of posterior shoulder instability

BACKGROUND

The ABC classification has recently been proposed as a comprehensive classification system for posterior shoulder instability (PSI). The purpose of this study was to analyze the comprehensiveness as well as inter-rater and intrarater reliability of the ABC classification.

METHODS

All consecutive patients presenting with unidirectional PSI from June 2019 to June 2021 were included in a prospective study. No patients were excluded, leaving a consecutive series of 100 cases of PSI in 91 patients. All recorded clinical and imaging data were used to create anonymized clinical case vignettes, which were evaluated twice according to the ABC classification at the end of the recruitment period in random sequential order by 4 independent raters (2 experienced shoulder surgeons and 2 orthopedic residents) to analyze the comprehensiveness as well as inter-rater and intrarater reliability of the ABC classification for PSI and to describe differences in characteristics among subtypes. Group A was defined as a first-time singular PSI event <3 months in the past regardless of etiology and is further subdivided into type 1 and type 2 depending on the occurrence of a subluxation (A1) or dislocation (A2). Group B comprises recurrent dynamic PSI regardless of time since onset and is further subdivided by the cause of instability into functional (B1) and structural (B2) dynamic PSI. Group C includes chronic static PSI with posterior humeral decentering that can be either constitutional (C1) or acquired (C2).

RESULTS

None of the cases was deemed unsuitable to be classified based on the proposed system by the observers. After consensus agreement between the 2 expert raters, 16 cases were attributed to group A (8 type A1 and 8 type A2); 64, to group B (33 type B1 and 31 type B2); and 20, to group C (11 type C1 and 9 type C2). The expert raters agreed on the classification subtypes in 99% and 96% of the cases during the first rating and second rating, respectively (intraclass correlation coefficients [ICCs], 0.998 and 0.99, respectively). The intraobserver reliability was excellent for both raters. The beginners reached the same conclusion as the consensus agreement in 94% of the cases (ICC, 0.99) and 89% of the cases (ICC, 0.97) during the first round and 94% each (ICC, 0.97) during the second round. The intraobserver reliability was excellent for both beginners. Overall, discrepancies between raters were found between groups B1 and B2 (n = 14), groups B2 and C2 (n = 4), groups B1 and C1 (n = 1), and groups A1 and B2 (n = 1). In general, each subtype showed distinctive clinical and imaging characteristics that facilitated the diagnosis.

CONCLUSION

The presented ABC classification for PSI is a comprehensive classification with a high reliability and reproducibility. However, a gradual transition and potential progression between the subtypes of PSI must be considered. The reliable distinction between different subtypes of PSI based on etiology and pathomechanism provides a standardized basis for future investigations on treatment recommendations.

Management of Bone Loss in Posterior Glenohumeral Shoulder Instability: Current Concepts

» Posterior glenohumeral instability is relatively uncommon compared with anterior instability, but is becoming an increasingly recognized and surgically managed shoulder pathology.» Soft-tissue stabilization alone may not be sufficient in patients who present with substantial bone loss to the posterior glenoid and/or the anterior humeral head.» For posterior glenoid defects, posterior glenoid osteoarticular augmentation can be used, and posterior glenoid opening wedge osteotomy can be considered in cases of posterior instability with pathologic retroversion.» For humeral head lesions, several surgical treatment options are available including subscapularis transposition into the humeral head defect, autograft or allograft reconstruction, humeral rotation osteotomy, and shoulder arthroplasty.

Outcomes of Concomitant Glenohumeral Stabilization After Arthroscopic Rotator Cuff Repair in Military Patients Younger Than 40 Years

Background

While concomitant rotator cuff and inferior labral tears are relatively uncommon in young civilians, military populations represent a unique opportunity to study this injury pattern.

Purpose

To (1) evaluate the long-term outcomes after combined arthroscopic rotator cuff and inferior labral repair in military patients <40 years and (2) compare functional outcomes with those after isolated arthroscopic rotator cuff repair.

Study Design

Cohort study; Level of evidence, 3.

Methods

Military patients who underwent arthroscopic rotator cuff repair between January 2011 and December 2016 and had a minimum of 5-year follow-up data were included in this study. The patients were categorized into those who had undergone combined arthroscopic rotator cuff and inferior labral repair (RCIL cohort) and those who had isolated arthroscopic rotator cuff repair (ARCR cohort). Pre- and postoperative outcome measures-visual analog scale for pain, Single Assessment Numeric Evaluation, American Shoulder and Elbow Surgeons shoulder score, Rowe Instability Score, and range of motion-were compared between the groups.

Results

A total of 50 shoulders (27 in the RCIL cohort and 23 in the ARCR cohort) were assessed. The RCIL and ARCR groups were similar in terms of age (mean, 33.19 years [range, 21-39 years] vs 35.39 years [range, 26-39 years], respectively) and sex (% male, 88.46% vs 82.61%, respectively). All patients were active-duty military at the time of surgery. The mean final follow-up was at 106.93 ± 16.66 months for the RCIL group and 105.70 ± 7.52 months for the ARCR group (P = .75). There were no differences in preoperative outcome scores between groups. Postoperatively, both groups experienced statistically significant improvements in all outcome scores (P < .0001 for all), and there were no significant group differences in any final postoperative outcome measures. At the final follow-up, 26 (96.30%) patients in the RCIL cohort and 20 (86.96%) in the ARCR cohort had returned to unrestricted active-duty military service (P = .3223).

Conclusion

The study findings indicate that concomitant glenohumeral stabilization does not prevent worse outcomes after arthroscopic rotator cuff repair in this military cohort. Combined repair produced statistically and clinically significant improvements in outcome scores at the long-term follow-up, indicating that simultaneous repair of combined lesions was an appropriate treatment option in this patient population.

No Difference in Recurrent Instability Between Knotted and Knotless Repair Techniques in Arthroscopic Treatment of Isolated Posterior Labral Tears: A Systematic Review

Purpose

To compare clinical failure, recurrent instability, patient-reported outcome measures (PROMs), and return to sport (RTS) between knotted and knotless fixation methods in arthroscopic posterior labral repair for isolated posterior shoulder instability (PSI).

Methods

Multiple databases were queried according to Preferred Reported Items for Systematic Reviews and Meta-Analyses guidelines for clinical studies with Level I to IV evidence, including knotted and knotless suture anchors for arthroscopic posterior labral repair. Combined anterior and posterior instability, multidirectional instability, SLAP injuries, unspecified repair techniques, majority open procedures, and revision surgery were excluded.

Results

Screening yielded 17 full-text articles reporting on 852 shoulders undergoing posterior labral repair. Recurrent instability ranged from 0% to 21%, and the rate of revision surgery ranged from 0% to 11% in knotted only, 0% in knotless only, and 2.0% to 8.1% in knotted and knotless studies. Six studies with both pre- and postoperative visual analog scale scores and 7 studies with both pre- and postoperative American Shoulder and Elbow Score scores all showed improvement in scores after intervention regardless of repair technique. Thirteen studies reported RTS or duty rates with a minimum of 79%.

Conclusions

Overall recurrent instability after posterior labral repair for isolated PSI was low with improvement in PROMs and favorable RTS rates regardless of fixation method. There was no clear difference in recurrent instability or revision surgery between knotted and knotless fixation methods for isolated posterior labral repair. However, the current literature is predominantly limited by Level III and IV evidence. The quality of literature and lack of standardization on the definition of clinical failure and recurrent instability among surgeons preclude any definitive conclusion regarding one clinically superior fixation method.

Level of Evidence

Level IV, systematic review of Level III and IV studies.

Establishing the Minimal Clinically Important Difference, Substantial Clinical Benefit, and Patient Acceptable Symptomatic State After Arthroscopic Posterior Labral Repair for Posterior Glenohumeral Instability

BACKGROUND

Posterior glenohumeral instability is an increasingly recognized cause of shoulder pain and dysfunction among young, active populations. Outcomes after posterior stabilization procedures are commonly assessed using patient-reported outcome measures including the Single Assessment Numeric Evaluation (SANE), the Rowe instability score, the American Shoulder and Elbow Surgeons (ASES) score, and the visual analog scale (VAS) for pain. The clinical significance thresholds for these measures after arthroscopic posterior labral repair (aPLR), however, remain undefined.

PURPOSE

We aimed to define the minimal clinically important difference (MCID), substantial clinical benefit (SCB), and patient acceptable symptomatic state (PASS) for the SANE, Rowe score, and ASES score as well as the VAS pain after aPLR. Additionally, we sought to determine preoperative factors predictive of reaching, as well as failing to reach, clinical significance.

STUDY DESIGN

Case-control study; Level of evidence, 3.

METHODS

This study was a retrospective analysis of patient-reported outcome scores collected from patients who underwent aPLR between January 2011 and December 2018. To determine the clinically significant threshold that corresponded to achieving a meaningful outcome, the MCID, SCB, and PASS were calculated for the SANE, Rowe score, ASES score, and VAS pain utilizing either an anchor- or distribution-based method. Additionally, univariate and multivariate logistic regression analyses were performed to determine the factors associated with achieving, or not achieving, the MCID, SCB, and PASS.

RESULTS

A total of 73 patients with a mean follow-up of 82.55 ± 24.20 months were available for final analysis. MCID, SCB, and PASS values for the VAS pain were 1.10, 6, and 3, respectively; for the ASES score were 7.8, 34, and 80, respectively; for the SANE were 10.15, 33, and 85, respectively; and for the Rowe score were 11.3, 60, and 90, respectively. To meet the MCID, male sex (odds ratio [OR], 1.1639; P = .0293) was found to be a positive predictor for the VAS pain, and a lower preoperative SANE score (OR, 0.9939; P = .0003) was found to be a negative predictor for the SANE. Dominant arm involvement was associated with lower odds of achieving the PASS for the ASES score (OR, 0.7834; P = .0259) and VAS pain (OR, 0.7887; P = .0436). Patients who reported a history of shoulder trauma were more likely to reach the PASS for the SANE (OR, 1.3501; P = .0089), Rowe score (OR, 1.3938; P = .0052), and VAS pain (OR, 1.3507; P = .0104) as well as the SCB for the ASES score (OR, 1.2642; P = .0469) and SANE (OR, 1.2554; P = .0444). A higher preoperative VAS pain score was associated with higher odds of achieving the SCB for both the VAS pain (OR, 1.1653; P = .0110) and Rowe score (OR, 1.1282; P = .0175). Lastly, concomitant biceps tenodesis was associated with greater odds of achieving the SCB for the ASES score (OR, 1.3490; P = .0130) and reaching the PASS for the SANE (OR, 1.3825; P = .0038) and Rowe score (OR, 1.4040; P = .0035).

CONCLUSION

To our knowledge, this study is the first to define the MCID, SCB, and PASS for the ASES score, Rowe score, SANE, and VAS pain in patients undergoing aPLR. Furthermore, we found that patients who reported a history of shoulder trauma and those who underwent concomitant biceps tenodesis demonstrated a greater likelihood of achieving clinical significance. Dominant arm involvement was associated with lower odds of achieving clinical significance.

Concomitant Biceps Tenodesis Does Not Portend Inferior Outcomes After Anterior Glenohumeral Stabilization

BACKGROUND

Military patients are known to suffer disproportionately high rates of glenohumeral instability as well as superior labrum anterior to posterior (SLAP) tears. Additionally, a concomitant SLAP tear is frequently observed in patients with anterior shoulder instability. Even though biceps tenodesis has been demonstrated to produce superior outcomes to SLAP repair in military patients with isolated SLAP lesions, no existing studies have reported on outcomes after simultaneous tenodesis and anterior labral repair in patients with co-existing abnormalities.

PURPOSE

To evaluate outcomes after simultaneous arthroscopic-assisted subpectoral biceps tenodesis and anterior labral repair in military patients younger than 40 years. We also sought to compare these outcomes with those after repair of an isolated anterior labral tear.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

This study is a retrospective analysis of all military patients younger than 40 years from a single base who underwent arthroscopic anterior glenohumeral stabilization with or without concomitant biceps tenodesis between January 2010 and December 2019. Patients with glenoid bone loss of >13.5% were not eligible for inclusion. Outcome measures including the visual analog scale (VAS) for pain, the Single Assessment Numeric Evaluation (SANE), the American Shoulder and Elbow Surgeons (ASES) shoulder score, the Rowe instability score, and range of motion were administered preoperatively and postoperatively, and scores were compared between groups.

RESULTS

A total of 82 patients met inclusion criteria for the study. All patients were active-duty service members at the time of surgery. The mean follow-up was 87.75 ± 27.05 months in the repair + tenodesis group and 94.07 ± 28.72 months in the isolated repair group (P = .3085). Patients who underwent repair + tenodesis had significantly worse preoperative VAS pain (6.85 ± 1.86 vs 5.02 ± 2.07, respectively; P < .001), ASES (51.78 ± 11.89 vs 62.43 ± 12.35, respectively; P = .0002), and Rowe (26.75 ± 7.81 vs 37.26 ± 14.91, respectively; P = .0002) scores than patients who underwent isolated repair. Both groups experienced significant improvements in outcome scores postoperatively (P < .0001 for all), and there were no statistically significant differences in postoperative outcome scores or range of motion between groups. There were no differences in the percentage of patients who achieved the minimal clinically important difference, substantial clinical benefit, and patient acceptable symptom state for the VAS pain, SANE, ASES, and Rowe scores between groups. Overall, 37 of the 40 (92.50%) patients in the repair + tenodesis group and 40 of the 42 (95.24%) patients in the isolated repair group returned to unrestricted active-duty military service (P = .6045). In addition, 38 (95.00%) patients in the repair + tenodesis group and 40 (95.24%) patients in the isolated repair group returned to preinjury levels of sporting activity (P = .9600). There were no significant differences in the number of failures, revision surgical procedures, or patients discharged from the military between groups (P = .9421, P = .9400, and P = .6045, respectively).

CONCLUSION

The findings of this study indicate that simultaneous biceps tenodesis and labral repair was a viable treatment option for the management of concomitant SLAP and anterior labral lesions in young, active military patients younger than 40 years.

Risk Factors for Glenoid Bone Loss in the Setting of Posterior Glenohumeral Instability

Background

Posterior instability has been reported to account for up to 24% of cases of shoulder instability in certain active populations. However, there is a paucity of data available regarding the risk factors associated with posterior glenoid bone loss.

Purpose

To characterize the epidemiology of, and risk factors associated with, glenoid bone loss within a cohort of patients who underwent primary arthroscopic shoulder stabilization for isolated posterior-type glenohumeral instability.

Study Design

Cross-sectional study; Level of evidence, 3.

Methods

This was a retrospective analysis of patients who underwent primary arthroscopic shoulder stabilization for posterior-type instability between January 2011 and December 2019. Preoperative magnetic resonance arthrograms were used to calculate posterior glenoid bone loss using a perfect circle technique. Patient characteristics and revision rates were obtained. Bone loss (both in millimeters and as a percentage) was compared between patients based on sex, age, arm dominance, sports participation, time to surgery, glenoid version, history of trauma, and number of anchors used for labral repair.

Results

Included were 112 patients with a mean age of 28.66 ± 10.07 years; 91 patients (81.25%) were found to have measurable bone loss. The mean bone loss was 2.46 ± 1.68 mm (8.98% ± 6.12%). Significantly greater bone loss was found in athletes versus nonathletes (10.09% ± 6.86 vs 7.44% ± 4.56; P = .0232), female versus male patients (11.17% ± 6.53 vs 8.17% ± 5.80; P = .0212), and patients dominant arm involvement versus nondominant arm involvement (10.26% ± 5.63 vs 7.07% ± 6.38; P = .0064). Multivariate regression analysis identified dominant arm involvement as an independent risk factor for bone loss (P = .0033), and dominant arm involvement (P = .0024) and athlete status (P = .0133) as risk factors for bone loss >13.5%. At the conclusion of the study period, 7 patients had experienced recurrent instability (6.25%).

Conclusion

The findings of this study are in alignment with existing data suggesting that posterior glenoid bone loss is highly prevalent in patients undergoing primary arthroscopic stabilization for posterior-type shoulder instability. Our results suggest that patients with dominant arm involvement are at risk for greater posterior glenoid bone loss. Athlete status and dominant arm involvement were identified as independent risk factors for bone loss >13.5%.

Simultaneous Arthroscopic Rotator Cuff Repair and Glenoid Microfracture in Active-Duty Military Patients Younger Than 50 Years: Outcomes at Midterm Follow-up

Background

While concomitant full-thickness rotator cuff tears and glenoid osteochondral defects are relatively uncommon in younger patients, military patients represent a unique opportunity to study this challenging injury pattern.

Purpose/Hypothesis

To compare the outcomes of young, active-duty military patients who underwent isolated arthroscopic rotator cuff repair (ARCR) with those who underwent ARCR plus concurrent glenoid microfracture (ARCR+Mfx). It was hypothesized that ARCR+Mfx would produce significant improvements in patient-reported outcome measures.

Study Design

Cohort study; Level of evidence, 3.

Methods

This was a retrospective analysis of consecutive active-duty military patients from a single base who underwent ARCR for full-thickness rotator cuff tears between January 2012 and December 2020. All patients were <50 years and had minimum 2-year follow-up data. Patients who underwent ARCR+Mfx were compared with those who underwent isolated ARCR based on the visual analog scale (VAS) for pain, Single Assessment Numeric Evaluation (SANE), American Shoulder and Elbow Surgeons (ASES) shoulder score, and range of motion.

Results

A total of 88 patients met the inclusion criteria for this study: 28 underwent ARCR+Mfx and 60 underwent isolated ARCR. The mean final follow-up was 74.11 ± 33.57 months for the ARCR+Mfx group and 72.87 ± 11.46 months for the ARCR group (P = .80). There were no differences in baseline patient characteristics or preoperative outcome scores between groups. Postoperatively, both groups experienced statistically significant improvements in all outcome scores (P < .0001 for all). However, the ARCR+Mfx group had significantly worse VAS pain (1.89 ± 2.22 vs 1.03 ± 1.70; P = .05), SANE (85.46 ± 12.99 vs 91.93 ± 12.26; P = .03), and ASES (86.25 ± 14.14 vs 92.85 ± 12.57; P = .03) scores. At the final follow-up, 20 (71.43%) patients in the ARCR+Mfx group and 53 (88.33%) patients in the ARCR group were able to remain on unrestricted active-duty military service (P = .05).

Conclusion

Concomitant ARCR+Mfx led to statistically and clinically significant improvements in patient-reported outcome measures at the midterm follow-up. However, patients who underwent ARCR+Mfx had significantly worse outcomes and were less likely to return to active-duty military service than those who underwent isolated ARCR. The study findings suggest that ARCR+Mfx may be a reasonable option for young, active patients who are not candidates for arthroplasty.

Epidemiology of shoulder dislocations presenting to United States emergency departments: An updated ten-year study

BACKGROUND

Glenohumeral dislocation is a common injury that may predispose patients to chronic pain and instability. However, there is a paucity of current data available regarding the epidemiological trends of this injury.

AIM

To provide an updated, comparative assessment of the epidemiology of shoulder dislocations presenting to emergency departments in the United States. We also sought to analyze patient demographic risk factors and consumer products associated with dislocation events.

METHODS

Data were obtained from the national electronic injury surveillance system database for glenohumeral dislocations between 2012 and 2021. Incidence, age, sex, and injury characteristics were analyzed using weighted population statistics as well as incidence rates and 95% confidence intervals (CI).

RESULTS

In total, an estimated 773039 shoulder dislocations (CI: 640598-905481) presented to emergency rooms across the United States during the study period. The annual incidence rate was 23.96 per 100000 persons and the average patient age at the time of injury was 37.1 years. Significantly more male patients sustained dislocations than female patients (537189, 69.5%, vs 235834, 30.5%, P < 0.001). With regard to associated consumer products, sports and recreation equipment were involved in the highest proportion of incidents (44.31%), followed by home structures and construction materials (21.22%), and home furnishings, fixtures, and accessories (21.21%). Regarding product sub-groups, stairs, ramps, landings, floors was cited in the greatest number of cases (131745).

CONCLUSION

The national annual incidence rate of glenohumeral dislocations throughout the study period was approximately 23.92 per 100000 persons. Male adolescents sustained the highest proportion of dislocations, with a peak incidence in age group 15-20 years, predominantly secondary to participation in sporting and recreational activities. Conversely, women experienced a relatively consistent incidence of dislocation throughout their lifespan. After age 63, the incidence rate of dislocations in females was found to surpass that observed in males.

Development and Validation of a Short-Form Version of the Western Ontario Shoulder Instability Scale (Short-WOSI)

BACKGROUND

Patient-reported outcome measures (PROMs) have transitioned from primarily being used as research instruments to becoming increasingly used in the clinical setting to assess recovery and inform shared decision-making. However, there is a need to develop validated short-form PROM instruments to decrease patient burden and ease incorporation into clinical practice.

PURPOSE

To assess the validity and responsiveness of a shortened version of the Western Ontario Shoulder Instability Index (Short-WOSI) when compared with the full WOSI and other shoulder-related PROM instruments.

STUDY DESIGN

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

METHODS

This study was a secondary analysis of data collected as part of an institutional review board-approved, multicenter cohort of 1160 patients undergoing surgical stabilization for shoulder instability. The following PROMs were captured preoperatively and 2 years after surgery: WOSI, American Shoulder and Elbow Surgeons (ASES) score, the Single Assessment Numeric Evaluation (SANE), and 36-Item Health Survey (RAND-36). The cohort was split into 2 data sets: a training set to be used in the development of the Short-WOSI (n = 580) and a test set to be used to assess the validity and responsiveness of the Short-WOSI relative to the full WOSI, ASES, SANE, and RAND-36.

RESULTS

The Short-WOSI demonstrated excellent internal consistency before surgery (Cronbach α = .83) and excellent internal consistency at the 2-year follow-up (Cronbach α = .93). The baseline, 2-year, and pre- to postoperative changes in Short-WOSI and WOSI were closely correlated (r > 0.90), with both demonstrating large effect sizes (Short-WOSI = 1.92, WOSI = 1.81). Neither the Short-WOSI nor the WOSI correlated well with the other PROM instruments before (r = 0.21-0.33) or after (r = 0.25-0.38) surgery. The Short-WOSI, WOSI, and SANE scores were more responsive than ASES and RAND-36 scores.

CONCLUSION

The 7-item Short-WOSI demonstrated excellent internal consistency and a lack of floor or ceiling effects. The Short-WOSI demonstrated excellent cross-sectional and longitudinal construct validity and was similarly responsive over time as the full WOSI. Neither the Short-WOSI nor WOSI correlated with more general shoulder PROMs, underscoring the advantage of using instability-specific instruments for this population.

Prevalence and Risk Factors of Glenoid Bone Loss in Combined Shoulder Instability in Young, Active-Duty Military Patients

Background

US military servicemembers experience higher rates of posterior and combined-type instability as compared with their nonmilitary peers.

Purpose

(1) To determine the prevalence of glenoid bone loss (GBL) in young, active-duty military patients with combined-type shoulder instability who underwent operative shoulder stabilization; (2) to evaluate whether GBL is associated with differences in postoperative outcomes; and (3) to identify factors associated with larger defects.

Study Design

Case series; Level of evidence, 4.

Methods

This study included active-duty military patients who underwent primary surgical shoulder stabilization for combined anterior and posterior capsulolabral tears between January 2012 and December 2018. Preoperative magnetic resonance arthrograms were used to calculate anterior, posterior, and total GBL using the "perfect circle" technique. We recorded patient characteristics, revisions, complications, return to duty, range of motion, and scores on multiple outcome measures (visual analog scale for pain, Single Assessment Numeric Evaluation, American Shoulder and Elbow Surgeons, and Rowe). GBL prevalence was compared by time to surgery, glenoid version, history of trauma, and number of anchors used for labral repair. Outcome scores, return to active duty, and revision procedures were compared by degree of anterior or posterior GBL: <13.5% (mild) versus ≥13.5% (subcritical).

Results

GBL was noted in 28 (77.8%) of the 36 patients. Nineteen (52.8%) patients had anterior GBL, 18 (50.0%) had posterior, and 9 (25.0%) had combined. Four (11.1%) patients had subcritical anterior or posterior GBL. Increased posterior GBL was associated with history of trauma (P = .041), time to surgery >12 months (P = .024), and glenoid retroversion ≥9° (P = .010); increased total GBL was associated with longer time to surgery (P = .023) and labral repair requiring >4 anchors (P = .012); and increased anterior GBL was associated with labral repair requiring >4 anchors (P = .011). There were statistically significant improvements on all outcome measures, with no changes in range of motion postoperatively. No significant difference on any outcome score was observed between patients with mild and subcritical GBL.

Conclusion

In our analysis, 78% of patients had appreciable GBL, suggesting that GBL is highly prevalent in this patient population. Longer time to surgery, traumatic cause, significant glenoid retroversion, and large labral tears were identified as risk factors for increased GBL.

Biomechanical Evaluation of Posterior Shoulder Instability With a Clinically Relevant Posterior Glenoid Bone Loss Model

BACKGROUND

Existing biomechanical studies of posterior glenoid bone loss and labral pathology are limited by their use of anterior instability models, which differ in both orientation and morphology and have been performed in only a single, neutral arm position.

PURPOSE

To evaluate the biomechanical effectiveness of a posterior labral repair in the setting of a clinically relevant posterior bone loss model in various at-risk arm positions.

STUDY DESIGN

Controlled laboratory study.

METHODS

Ten fresh-frozen cadaveric shoulders were tested in 7 consecutive states using a 6 degrees of freedom robotic arm: (1) native, (2) posterior labral tear (6-9 o'clock), (3) posterior labral repair, (4) mean posterior glenoid bone loss (7%) with labral tear, (5) mean posterior glenoid bone loss with labral repair, (6) large posterior glenoid bone loss (28%) with labral tear, and (7) large posterior glenoid bone loss with labral repair. Bone loss was created using 3-dimensional printed computed tomography model templates. Biomechanical testing consisted of 75 N of posterior-inferior force and 75 N of compression at 60° and 90° of flexion and scaption. Posterior-inferior translation, lateral translation, and peak dislocation force were measured for each condition.

RESULTS

Labral repair significantly increased dislocation force independent of bone loss state between 10.1 and 14.8 N depending on arm position. Dislocation force significantly decreased between no bone loss and small bone loss (11.9-13.5 N), small bone loss and large bone loss (9.4-14.3 N), and no bone loss and large bone loss (21.2-26.5 N). Labral repair significantly decreased posterior-inferior translation compared with labral tear states by a range of 1.0 to 2.3 mm. In the native state, the shoulder was most unstable in 60° of scaption, with 29.9 ± 6.1-mm posterior-inferior translation.

CONCLUSION

Posterior labral repair improved stability of the glenohumeral joint, and even in smaller to medium amounts of posterior glenoid bone loss the glenohumeral stability was maintained with labral repair in this cadaveric model. However, a labral repair with large bone loss could not improve stability to the native state.

CLINICAL RELEVANCE

This study shows that larger amounts of posterior glenoid bone loss (>25%) may require bony augmentation for adequate stability.

Diagnosis of Posterior and Combined-Type Shoulder Instability: A 10-Year Cross-sectional Study From a Single Military Base

Background

Large variations exist in the reported frequency and etiology of posterior and combined shoulder instability in the active-duty military population.

Purpose

To compare imaging and clinical examination findings as well as reoperation rates between active-duty military patients who underwent surgery for anterior, posterior, and combined-type shoulder instability.

Study Design

Cross-sectional study; Level of evidence, 3.

Methods

A retrospective review was conducted on patients treated surgically for shoulder instability from a single military base from January 2010 to December 2019. Each case was characterized as isolated anterior, isolated posterior, or combined, according to arthroscopic findings. Information was collected on patient characteristics, history of trauma, time to surgery, associated pathological findings, and survivorship at a minimum 2-year follow-up.

Results

Overall, 416 patients (n = 394 men; n = 22 women), with a mean age of 29.1 years, underwent primary shoulder stabilization surgery during the study period. There were 158 patients (38%) with isolated anterior instability, 139 (33%) with isolated posterior instability, and 119 (29%) with combined instability. A history of trauma was more prevalent with isolated anterior instability (129 [81.7%]) than with either isolated posterior (95 [68.4%]) or combined instability (73 [61.3%]) (P = .047 and P = .001, respectively). Patients with anterior instability were significantly more likely to be diagnosed on the preoperative physical examination when compared with patients with posterior instability (93% vs 79.1%; P < .001) or combined instability (93% vs 75.6%; P < .001) and were also more likely to have a discrete labral tear detected on a preoperative magnetic resonance arthrogram than patients with posterior instability (82.9% vs 63.3%; P < .001). There was no significant difference in the rate of medical discharge or recurrent instability requiring reoperation between groups.

Conclusion

The study findings indicated that young, active-duty military patients are at increased risk for isolated posterior and combined-type shoulder instability, with posterior and combined instability collectively accounting for over 60% of instability cases in this cohort. Orthopaedic surgeons should be aware of instability when evaluating and treating young, active-duty military patients with shoulder pain, even in the absence of diagnostic physical examinations or imaging findings.

Posterior Labral Repair Using Knotless "All-Suture" Suture Anchors

Isolated posterior instability is well described but relatively uncommon, accounting for less than 10% of all shoulder instability cases. When nonoperative management fails, surgical outcomes demonstrate improved patient-reported outcomes with a high level of return to sport. Knotless suture anchor and "all-suture" suture anchor technology are now available and used for instability procedures in the shoulder. This technical description describes knotless "all-suture" suture anchor fixation for isolated posterior labral tears.

Simultaneous Arthroscopic Glenohumeral Stabilization and Glenoid Microfracture in Young, Active-Duty Military Patients: Outcomes at 5-Year Follow-up

Background

Glenohumeral instability represents a common cause of shoulder pain and disability among active-duty members of the military and is associated with the development of glenoid osteochondral defects.

Purpose

To report clinical outcomes and survivorship after combined microfracture of isolated chondral lesions of the glenoid and labral repair among young, active-duty military patients and to compare outcomes with those of patients who underwent isolated shoulder stabilization.

Study Design

Cohort study; Level of evidence, 3.

Methods

Included were 31 active-duty military patients aged <40 years who underwent simultaneous microfracture of chondral lesions of the glenoid and labral repair for shoulder instability between January 2011 and January 2017 (microfracture group) and 209 patients without chondral defects who underwent shoulder stabilization during the same time period (instability group). Preoperative and 5-year postoperative outcomes (range of motion [ROM], visual analog scale [VAS] for pain, Single Assessment Numeric Evaluation [SANE] score, American Shoulder and Elbow Surgeons [ASES] shoulder score, and Rowe instability score) were compared within and between groups, and separate subgroup analyses were performed to determine whether variant of instability and dominant-shoulder involvement were associated with worse outcomes.

Results

The mean follow-up was significantly longer for the microfracture group versus the instability group (95.58 ± 23.12 vs 83.38 ± 25.93 months; P = .014). Age and sex distributions were similar between groups. In both groups, there was significant pre- to postoperative improvement on all outcomes scores (P = .0001 for all). When compared with the instability cohort, microfracture patients had significantly worse postoperative VAS pain (2.65 ± 1.78 vs 1.55 ± 1.92; P = .003), SANE (79.13 ± 14.43 vs 91.23 ± 13.20; P < .0001), and ASES (79.90 ± 13.87 vs 89.03 ± 14.28; P = .001) scores, as well as decreased ROM in forward flexion (151.29° ± 11.76° vs 155.48° ± 10.3°; P = .039) and external rotation (63.65° ± 8.34° vs 65.17° ± 0.64°; P = .010). At latest follow-up, 58% of microfracture patients had returned to active-duty military service compared with 93.78% of isolated instability patients (P < .0001).

Conclusion

Combined microfracture and arthroscopic labral repair produced modest, albeit statistically significant, improvements in patient-reported outcome measures and may be a reasonable treatment option for patients with chondral lesions who are not candidates for arthroplasty. However, microfracture patients had significantly worse outcomes than patients who underwent stabilization without concomitant chondral defects.

Glenoid Avulsion of the Glenohumeral Ligament Repair Through a Single Working Portal

Glenoid avulsion of the glenohumeral ligament (GAGL) is a traumatic cause of shoulder instability. GAGL lesions are a rare shoulder pathology most commonly reported as a source of anterior shoulder instability, with no current reports implicating this pathology as a cause of posterior instability. Satisfactory surgical repairs of GAGL lesions with anterior shoulder instability have been well documented; however, this Technical Note highlights the successful repair of a posterior GAGL lesion through a single working portal with suture anchor fixation of the posterior capsule.

Epidemiology of Musculoskeletal Injuries in the Navy: A Systematic Review

Objectives: This study aimed to critically review the results of recent studies that investigated the epidemiology of noncombat-related musculoskeletal injuries (MSIs) in the Navy. Methods: A systematic search was conducted of three major databases (Pubmed, Embase, and Cochrane) to identify epidemiological studies on MSIs in the Navy. Study selection and risk of bias assessment were conducted. Results: The overall prevalence of MSIs ranged from 12.69% to 48.81%. And the prevalence of head and face injuries, upper extremity injuries, spine injuries, chest injuries, and lower extremity injuries were 0.11%-0.66%, 0.53%-11.47%, 0.75%-12.09%, 0.43%-0.95%, and 0.4%-21.17%, respectively. For the specific MSIs, the incidence ranged from 0.03/1000 person-years to 32.3/1000 person-years in the Navy and Marines. The ankle-foot, lumbopelvic, knee and lower leg, and shoulder were identified as the most frequent location for MSIs. Conclusion: This systematic review summarized that the Navy population had a high prevalence of MSIs. And different risk factors for MSIs varied from different anatomic locations. This systematic review also provided valuable information on MSIs for sports medicine specialists.

Arthroscopic Posterior Labral Repair in Active-Duty Military Patients: A Reliable Solution for an At-Risk Population, Regardless of Anchor Type

BACKGROUND

Active-duty servicemembers are a population at risk for the development of posterior shoulder instability. While short-term outcomes after arthroscopic posterior labral repair for posterior shoulder instability are promising, there is a paucity of longer term follow-up data for this procedure.

PURPOSES

The primary purpose was to report midterm outcomes after arthroscopic posterior labral repair in active-duty military patients for posterior shoulder instability without bone loss. The secondary purpose was to determine if outcomes varied between anchor types used.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

Preoperative and postoperative outcomes, with a minimum 3-year follow-up, for a visual analog scale for pain, the Single Assessment Numeric Evaluation (SANE), the American Shoulder and Elbow Surgeons (ASES) score, and the Rowe score were collected and analyzed. A separate subgroup analysis was performed comparing the outcomes of patients who underwent repair with biocomposite anchors versus those who underwent repair with all-suture anchors.

RESULTS

A total of 73 patients with a mean follow-up of 82.55 ± 24.20 months met the inclusion criteria and were available for analysis. As a whole, the cohort demonstrated statistically and clinically significant improvements in outcome scores at final follow-up. Preoperative and postoperative range of motion did not vary significantly. While the difference in final outcome scores between the 2 anchor types did not reach statistical significance, a statistically significantly larger proportion of patients who underwent repair with all-suture anchors versus those who underwent repair with biocomposite anchors met the Patient Acceptable Symptom State for the SANE (97.14% vs 78.95%, respectively; P = .0180) and the ASES score (88.57% vs 68.42%, respectively; P = .0171). The proportion of patients who achieved the substantial clinical benefit or surpassed the minimal clinically important difference, however, did not vary by anchor type. Overall, 70 patients (95.89%) remained on active duty and were able to return to preinjury work and recreational activity levels. There were 3 patients (4.11%) who had recurrent posterior instability.

CONCLUSION

This population of active-duty servicemembers undergoing posterior labral repair for posterior labral instability without bone loss demonstrated a statistically and clinically significant improvement in midterm outcomes, a low recurrence rate, and a rate of return to active duty of 95.89%, regardless of the anchor type used.

Arthroscopic Posterior Labral Repair and Capsular Closure via Single Working Portal for Posterior Shoulder Instability

Posterior shoulder instability (PSI) is a relatively less common form of instability that frequently affects young overhead or contact athletes. The etiology of PSI may be traumatic or atraumatic, with establishment of the diagnosis being more difficult in cases of atraumatic instability. Surgical management of PSI has evolved from open techniques to arthroscopic techniques. Posterior stabilization has commonly been performed with 2 posterior working portals with the patient in the lateral decubitus position. The objective of this Technical Note is to describe a technique for posterior labral repair using all-suture anchors with the patient in the beach-chair position via 1 working portal with capsular closure.

Long-term Results of Arthroscopic Repair of Full-Thickness Traumatic Rotator Cuff Tears in Active Duty Military Patients Under the Age of 40 Years

BACKGROUND

Arthroscopic rotator cuff repair is an effective procedure through which to decrease pain and increase strength, with favorable long-term outcomes demonstrated in older patient populations with full-thickness rotator cuff tears. The long-term outcomes after this procedure in younger, higher-demand patients, however, is not as clearly defined.

PURPOSE

To report on the long-term outcomes after arthroscopic rotator cuff repair of traumatic full-thickness rotator cuff tears in active duty military patients under the age of 40 years at the time of surgery.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

Preoperative, midterm, and final evaluations were collected, including scores on the visual analog scale for pain, Single Assessment Numeric Evaluation, and American Shoulder and Elbow Surgeons shoulder form. A total of 42 patients were screened for inclusion: 3 underwent additional surgical procedures on the operative shoulder and 2 were lost to follow-up, leaving 37 patients with mean follow-up of 104.51 months available for analysis. A subgroup analysis was performed comparing outcomes between patients with Southern California Orthopaedic Institute grade 1 or 2 tears and those with grade 3 or 4 tears.

RESULTS

At final follow-up, pain per the visual analog scale decreased to 1.16 from 8.03 (P < .0001); the Single Assessment Numeric Evaluation score increased to 87.32 from 48.24 (P < .0001); and the American Shoulder and Elbow Surgeons score increased to 88.68 from 41.00 (P < .0001). There was no statistically significant difference in outcome scores or range of motion between midterm and final follow-up. Improvement in outcome scores and range of motion at final follow-up did not vary between patients with small and large tears. Of 42 patients, 37 (88.1%) were able to return to full unrestricted active duty and sporting activity, while 5 (11.9%) were medically separated from the military.

CONCLUSION

Active duty military patients under the age of 40 years with traumatic full-thickness rotator cuff tears had statistically and clinically significant increases in outcome scores and decreases in pain after arthroscopic rotator cuff repair at long-term follow-up.

Social and Demographic Factors Impact Shoulder Stabilization Surgery in Anterior Glenohumeral Instability

Purpose

To assess independent predictors of surgery after an emergency department visit for shoulder instability, including patient-related and socioeconomic factors.

Methods

Patients presenting to the emergency department were identified in the New York Statewide Planning and Research Cooperative System database from 2015 to 2018 by International Classification of Diseases, Tenth Revision, Clinical Modification diagnosis codes for anterior shoulder dislocation or subluxation. All shoulder stabilization procedures in the outpatient setting were identified using Current Procedural Terminology codes (23455, 23460, 23462, 23466, and 29806). A multivariable logistic regression was performed to assess the impact of patient factors on the likelihood of receiving surgery. The variables included in the analysis were age, sex, race, social deprivation, Charlson Comorbidity Index, recurrent dislocation, and primary insurance type.

Results

In total, 16,721 patients with a shoulder instability diagnosis were included in the analysis and 1,028 (6.1%) went on to have surgery. Patients <18 years old (odds ratio [OR] 8.607, P < .0001), those with recurrent dislocations (OR 2.606, P < .0001), or worker’s compensation relative to private insurance (OR 1.318, P = .0492) had increased odds of receiving surgery. Hispanic (OR 0.711, P = .003) and African American (OR 0.63, P < .0001) patients had decreased odds of surgery compared with White patients. Patients with Medicaid (OR 0.582, P < .0001) or self-pay (OR 0.352, P < .0001) insurance had decreased odds of undergoing surgery relative to privately insured patients. Patients with greater levels of social deprivation (OR 0.993, P < .0001) also were associated with decreased odds of surgery.

Conclusions

Anterior glenohumeral instability and subsequent stabilization surgery is associated with disparities among patient race, primary insurance, and social deprivation.

Clinical Relevance

Considering the relationship between differential care and health disparities, it is critical to define and increase physician awareness of these disparities to help ensure equitable care.

Midterm Outcomes After Arthroscopic Repair of Type VIII SLAP Lesions in Active Duty Military Patients Younger Than 35 Years

Background

Superior labrum from anterior to posterior (SLAP) lesions represent a significant cause of shoulder pain and disability among active duty members of the US military. However, few data exist regarding the surgical management of type VIII SLAP lesions.

Hypothesis

We hypothesized that arthroscopic repair would decrease pain and increase function at the midterm follow-up and allow for a high rate of maintenance of active duty status.

Study Design

Case series; Level of evidence, 4.

Methods

Consecutive active duty military patients were identified from January 2011 through June 2015 who underwent arthroscopic repair of type VIII SLAP lesions performed by a single surgeon. Patients were excluded if they underwent glenoid microfracture, other capsulolabral repair, or rotator cuff repair. Outcome measures were completed by patients within 1 week before surgery and at latest follow-up: pain visual analog scale, Single Assessment Numeric Evaluation, American Shoulder and Elbow Surgeons shoulder score, and Rowe instability score.

Results

A total of 30 patients met the inclusion criteria for the study. The mean ± SD follow-up was 96.60 ± 10.91 months. At final follow-up, the mean visual analog scale score improved from 8.17 ± 1.6 to 1.63 ± 1.90 (P < .0001), the Single Assessment Numeric Evaluation score from 41.65 ± 16.78 to 87.63 ± 13.02 (P < .0001), the American Shoulder and Elbow Surgeons score from 36.47 ± 10.26 to 88.07 ± 13.94 (P < .0001), and the Rowe score from 35.33 ± 6.56 to 90.00 ± 14.68 (P < .0001). Three patients reported postoperative complications, and 1 progressed to further surgery. Overall, 90% of patients remained on active duty military service and were able to return to preinjury levels of work and recreational activity. The failure rate, defined as persistent instability or activity-limiting pain, was 10%.

Conclusion

The results of this study demonstrated favorable outcomes for the majority of patients after arthroscopic repair of type VIII SLAP lesions at midterm follow-up, supporting repair as a viable treatment option for type VIII SLAP tears in this patient population.

Posterior Glenoid Osteotomy With Capsulolabral Repair Improves Resistance Forces in a Critical Glenoid Bone Loss Model

Background:

There is no widespread consensus on the surgical treatment of posterior shoulder instability with critical posterior glenoid bone loss.

Hypothesis:

That opening posterior glenoid wedge osteotomy with soft tissue repair would improve the resistance forces of instability when compared with soft tissue repair alone in the setting of 20% critical bone lose.

Study Design:

Controlled laboratory study.

Methods:

Native glenoid retroversion was measured on 9 shoulders using computed tomography (CT) scans. The humerus was potted in 90° of forward flexion and 30° of internal rotation relative to the scapula, and a posterior dislocation was performed to create a posterior capsulolabral injury model. The specimens were each taken through a fixed sequence of testing: (1) posteroinferior capsulolabral tear, (2) no glenoid bone loss with posteroinferior capsulolabral repair, (3) 20% posterior glenoid bone loss with posteroinferior capsulolabral repair, and (4) 20% glenoid bone loss with posterior glenoid opening wedge osteotomy and posteroinferior capsulolabral repair. Bone loss was created using a sagittal saw. The resultant peak forces with 1 cm of posterior translation were measured. A 1-way repeated-measures analysis of variance was used to compare mean force values.

Results:

After the initial dislocation event, all shoulders had a resultant posterior capsulolabral injury. The resulting labral injury was extended from 6- to 9-o’clock in all specimens to homogenize the extent of injury. Repairing the capsulolabral complex in the 20% posterior glenoid bone loss group did not result in a statistically significant increase in resistance force compared with the labral deficient group (34.1 vs 22.2 N; P = .068). When 20% posterior bone loss was created, the posterior glenoid osteotomy with capsulolabral repair was significantly stronger (43.8 N) than the posterior repair alone both with (34.1 N) and without (31.8 N) bone loss (P = .008 and .045, respectively).

Conclusion:

In the setting of critical posterior glenoid bone loss, an opening wedge posterior glenoid osteotomy with capsulolabral repair improved resistance to posterior humeral translation significantly compared with capsulolabral repair alone.

Clinical Relevance:

The results of this biomechanical cadaveric study may aid in surgical planning for this complex patient population.

The Cartilage Wear Index: A new evaluation method to improve patient selection in surgical treatment of recurrent posterior glenohumeral instability

Background

The purpose of this study was to validate glenoid cartilage lesions as a negative prognostic factor and to define a new image-based preoperative evaluation method to identify surgical candidates for arthroscopic labral refixation with suture anchors in posterior shoulder instability.

Methods

Twenty-six patients who underwent arthroscopic posterior labral repair for shoulder instability were evaluated. Only patients with structural dynamic posterior instability were included. We evaluated on preoperative magnetic resonance arthrogram: glenoid version, humeral head subluxation, type of capsular insertion, and the cartilage lesions using the new Cartilage Wear Index (CWI). Two subgroups were analyzed with regard to the preoperative CWI and shoulder outcome scores: Single Assessment Numerical Evaluation (SANE) and Western Ontario Shoulder Instability Index (WOSI).

Results

The median age at operation was 28 (interquartile range = 21-33) years. Median overall postoperative outcome assessment demonstrated a SANE of 90 and a WOSI of 385. The median CWI was 1.02. Subgroup analysis revealed worse median WOSI and SANE scores in patients with a CWI >1.02 and a strong correlation between a high preoperative CWI and a higher postoperative WOSI score (R = 0.58; P = .038).

Conclusion

The CWI can be useful to identify patients who might obtain better outcomes when treated with arthroscopic labral repair in posterior shoulder instability.