Treatment Of Posterior Shoulder Instability Research Articles

The Kouvalchouk Procedure versus Distal Tibial Allograft for Treatment of Posterior Shoulder Instability: The Deltoid “Hammock” Effect Exists

BackgroundIn 1993, Kouvalchouk described an acromial bone block with a pedicled deltoid flap for the treatment of posterior shoulder instability. This procedure provides a “double blocking” effect in that the acromial autograft restores posterior glenoid bone loss and the deltoid flap functions as a muscular “hammock” resembling the sling effect of the conjoint in the Latarjet procedure. The primary aim of this study was to compare the Kouvalchouk procedure to distal tibial allograft (DTA) reconstruction for the management of posterior shoulder instability with associated bone loss, while the secondary aim was to evaluate the deltoid hammock effect. s MethodsTen upper extremity cadavers were evaluated using a validated shoulder testing apparatus in 0° and 60° of glenohumeral abduction in the scapular plane. Testing was first performed on the normal shoulder state and was followed by the creation of a 20% posterior glenoid defect. Subsequently, the Kouvalchouk and DTA procedures were conducted. Forces of 0N, 5N, 10N and 15N were applied to the posterior deltoid tendinous insertion on the Kouvalchouk graft along the physiological muscle line-of-action to evaluate the ‘hammock” effect of this procedure. Testing was additionally performed on the Kouvalchouk bone graft with the deltoid muscle sectioned from its bony attachment. For all test states, a posteriorly directed force was applied to the humeral head perpendicular to the direction of the glenoid bone defect, with the associated translation quantified using an optical tracking system. The outcome variable was posterior translation of the humeral head at an applied force magnitude of 30N. ResultsThe Kouvalchouk procedure with the loaded deltoid flap (10N: P=0.039 and 15N: P<0.001) was significantly better at reducing posterior humeral head translation than the DTA. Overall, increased glenohumeral stability was observed with increased force applied to the posterior deltoid flap in the Kouvalchouk procedure. The 15N Kouvalchouk was most effective at preventing posterior humeral translation, and the difference was statistically significant compared with the 20% glenoid defect (P=0.003), detached Kouvalchouk (P<0.001), and 0N Kouvalchouk (P<0.001). The 15N Kouvalchouk procedure restored posterior shoulder joint stability to near normal levels, such that it was not significantly different from the intact state (P=0.203). ConclusionsThe Kouvalchouk procedure with load applied to the deltoid was found to be biomechanically superior to the DTA for the management of posterior shoulder instability with associated bone loss. Additionally, the results confirmed the presence and effectiveness of the deltoid “hammock” effect.

Posterior Shoulder Instability, Part I—Diagnosis, Nonoperative Management, and Labral Repair for Posterior Shoulder Instability—An International Expert Delphi Consensus Statement

To establish consensus statements on the diagnosis, nonoperative management, and labral repair for posterior shoulder instability. A consensus process on the treatment of posterior shoulder instability was conducted, with 71 shoulder/sports surgeons from 12 countries participating on the basis of their level of expertise in the field. Experts were assigned to 1 of 6 working groups defined by specific subtopics within posterior shoulder instability. Consensus was defined as achieving 80% to 89% agreement, whereas strong consensus was defined as 90% to 99% agreement, and unanimous consensus was indicated by 100% agreement with a proposed statement. Unanimous agreement was reached on the indications for nonoperative management and labral repair, which include whether patients had primary or recurrent instability, with symptoms/functional limitations, and whether there was other underlying pathology, or patient's preference to avoid or delay surgery. In addition, there was unanimous agreement that recurrence rates can be diminished by attention to detail, appropriate indication and assessment of risk factors, recognition of abnormalities in glenohumeral morphology, careful capsulolabral debridement and reattachment, small anchors with inferior placement and multiple fixation points that create a bumper with the labrum, treatment of concomitant pathologies, and a well-defined rehabilitation protocol with strict postoperative immobilization. The study group achieved strong or unanimous consensus on 63% of statements related to the diagnosis, nonoperative treatment, and labrum repair for posterior shoulder instability. The statements that achieved unanimous consensus were the relative indications for nonoperative management, and the relative indications for labral repair, as well as the steps to minimize complications for labral repair. There was no consensus on whether an arthrogram is needed when performing advanced imaging, the role of corticosteroids/orthobiologics in nonoperative management, whether a posteroinferior portal is required. Level V, expert opinion.

Diagnosis and treatment of posterior shoulder instability based on the ABC classification.

Posterior shoulder instability (PSI) is less common than anterior shoulder instability, accounting for 2-12% of total shoulder instability cases. However, a much higher frequency of PSI has been recently indicated, suggesting that PSI accounts for up to 24% of all young and active patients who are surgically treated for shoulder instability. This differentiation might be explained due to the frequent misinterpretation of vague symptoms, as PSI does not necessarily present as a recurrent posterior instability event, but often also as mere shoulder pain during exertion, limited range of motion, or even as yet asymptomatic concomitant finding. In order to optimize current treatment, it is crucial to identify the various clinical presentations and often unspecific symptoms of PSI, ascertain the causal instability mechanism, and accurately diagnose the subgroup of PSI. This review should guide the reader to correctly identify PSI, providing diagnostic criteria and treatment strategies.

Posterior Shoulder Instability Part II – Glenoid Bone-Grafting, Glenoid Osteotomy, and Rehabilitation/Return to Play – An International Expert Delphi Consensus Statement

The purpose of this study was to establish consensus statements on glenoid bone-grafting, glenoid osteotomy, rehabilitation, return to play, and follow-up for posterior shoulder instability. A consensus process on the treatment of posterior shoulder instability was conducted, with 71 shoulder/sports surgeons from 12 countries participating based on their level of expertise in the field. Experts were assigned to one of 6 working groups defined by specific subtopics within posterior shoulder instability. Consensus was defined as achieving 80-89% agreement, whereas strong consensus was defined as 90-99% agreement, and unanimous consensus was indicated by 100% agreement with a proposed statement. All of the statements relating to rehabilitation, return to play, and follow-up achieved consensus. There was unanimous consensus that the following criteria should be considered: restoration of strength, range of motion, proprioception, and sport-specific skills, with a lack of symptoms. There is no minimum time point required to return to play. Collision athletes and military athletes may take longer to return because of their higher risk for recurrent instability, and more caution should be exercised in clearing them to return to play, with elite athletes potentially having different considerations in returning to play. The relative indications for revision surgery are symptomatic apprehension, multiple recurrent instability episodes, further intra-articular pathologies, hardware failure, and pain. The study group achieved strong or unanimous consensus on 59% of statements. Unanimous consensus was reached regarding the criteria for return to play, collision/elite athletes having different considerations in return to play, indications for revision surgery, and imaging only required as routine for those with glenoid bone-grafting/osteotomies at subsequent follow-ups. There was no consensus on optimal fixation method for a glenoid bone-block, the relative indications for glenoid osteotomy, whether fluoroscopy is required or if the labrum should be concomitantly repaired. Level V Expert Opinion.

The Posterior Shoulder Instability Questionnaire (PSI-Q): Internal consistency, content and criterion validity, responsiveness, and reliability of a new tool for the assessment of posterior shoulder instability

Posterior shoulder instability (PSI) is an increasingly recognized cause of shoulder dysfunction particularly in young active patients and certain athlete populations. When evaluating the efficacy of treatment for PSI, specific outcome measures for this population are essential. The aim of the current research was to describe the development and evaluation of a patient reported outcome measure (PROM) specific for PSI. A retrospective cohort study design of patients with PSI was used to develop and evaluate the "Posterior Shoulder Instability Questionnaire (PSI-Q)". Items for PSI-Q were generated through an expert focus group and existing questionnaires. Preliminary data analysis identified redundancy of items and resulted in the PSI-Q being refined. The final PSI-Q was evaluated on 128 patients with PSI with a structural lesion requiring surgical intervention. Participants were excluded in the absence of a posterior glenohumeral joint lesion. Internal consistency (Cronbach α and corrected item-total correlation), content validity, criterion validity, responsiveness, and test-retest reliability (intraclass correlation coefficient; ICC) were examined. Content validity, criterion validity and responsiveness were compared with the Melbourne Instability Shoulder Score (MISS) and the Western Ontario Shoulder Index (WOSI). The minimum detectable change score (MDC) was calculated. The Cronbach α for the total scale pre and post-intervention was high (α = 0.97). All five domains (Pain, Instability/Weakness/Stiffness, Function, Occupation and Sport, and Quality of Life and Satisfaction) demonstrated acceptable internal consistency for each subsection and the overall score of the scale (α > 0.70). The corrected-item total correlation for each domain were within an acceptable range. The responsiveness of the PSI-Q questionnaire was excellent (effect size, 2.06; standard response mean, 1.34) and was higher than the MISS and WOSI. There were no relevant floor effects and one ceiling effect. Reliability was excellent (ICC (1,1) = 0.93) and the calculated MDC was 10.9 points. This study designed and validated a questionnaire specific for measuring symptoms and function in people with structural PSI requiring surgery. The PSI-Q demonstrates good measurement properties and provides an MDC that is useful for researchers and clinicians. In structural PSI, the PSI-Q has a higher responsiveness and more accurately reflects a patient's overall perceived shoulder status compared to current patient reported outcomes for shoulder instability. The psychometric properties of the PSI-Q are still to be determined in a non-surgical population.

Open treatment of posterior glenoid bone loss and bipolar bone loss.

Posterior glenohumeral instability is an increasingly common and challenging orthopaedic problem. While an arthroscopic soft tissue stabilization procedure (i.e., reverse Bankart repair) is effective in treating most cases of posterior instability, this procedure may be inadequate in shoulders with critical posterior glenoid bone loss (GBL), or in cases of an engaging reverse Hill-Sachs lesion. Thus, the purpose of the present manuscript was to report contemporary surgical approaches, techniques, and outcomes for the open treatment of glenoid or humeral head bone loss in posterior instability to help guide clinical decision making. Open osteoarticular augmentation procedures have emerged as a popular option to treat posterior bone loss, with bony auto- and allografts utilized from a variety of donor sites including iliac crest, scapular spine, acromion, distal clavicle, and distal tibia. The combination of glenoid retroversion and bone loss can be addressed with a posterior glenoid opening wedge osteotomy. Bipolar bone loss may be treated with a combination of the aforementioned techniques, in addition to a reverse remplissage, a modified McLaughlin procedure, or various arthroplasty-related options. Although short and mid-term outcomes are dependable, studies reporting long-term outcomes are sparse. Moreover, there is no current consensus regarding the most effective treatment of posterior shoulder instability in the setting of bone loss, and open surgical techniques continue to evolve. Further research is necessary to determine long-term effectiveness of these surgical options.

Posterior Shoulder Instability in Tennis Players: Aetiology, Classification, Assessment and Management.

Micro-traumatic posterior shoulder instability (PSI) is an often missed and misdiagnosed pathology presenting in tennis players. The aetiology of micro-traumatic PSI in tennis players is multifactorial, including congenital factors, loss of strength and motor control, and sport-specific repetitive microtrauma. Repetitive forces placed on the dominant shoulder, particularly combinations of flexion, horizontal adduction, and internal rotation contribute to the microtrauma. These positions are characteristic for kick serves, backhand volleys, and the follow-through phase of forehands and serves. The aim of this clinical commentary is to present an overview of the aetiology, classification, clinical presentation, and treatment of micro-traumatic PSI, with a particular focus on tennis players. 5.

Arthroscopic Stabilization of Posterior Shoulder Instability Without Glenoid Bone Loss

Background: Contact athletes who experience posterior shoulder instability have a high likelihood of recurrence necessitating surgery. Indications: Patients with posterior shoulder instability without glenoid or humeral head bone loss who have failed activity modification, bracing, and physical therapy may benefit from arthroscopic stabilization surgery. Technique Description: We describe a technique for arthroscopic labral repair with capsular plication through 4 portals in the lateral decubitus position. Results: Arthroscopic capsulolabral reconstruction is an effective and reliable treatment for posterior shoulder instability with good patient-reported outcomes, low recurrence rates, and high rate of return-to-play. Discussion/Conclusion: Arthroscopic capsulolabral reconstruction in the lateral decubitus position with appropriately placed portals allows for safe and effective repair of the labrum and capsular plication to address posterior shoulder instability. The author(s) attests that consent has been obtained from any patient(s) appearing in this publication. If the individual may be identifiable, the author(s) has included a statement of release or other written form of approval from the patient(s) with this submission for publication.

Trends in the surgical treatment of posterior shoulder instability in the United States from 2016 to 2020.

The purpose of this study was to describe trends in the incidence of open versus arthroscopic management of posterior shoulder instability (PSI) as well as the patients undergoing these procedures in the United States over time. The PearlDiver Patient Records Database was utilized for this study. Cases of PSI and surgery were identified via the appropriate ICD-10-CM and CPT codes. Linear regression and two-sample Student's t-test were used to analyze incidence rates, procedure type, number of instability events, and patient age. A total of 5655 patients were identified as having PSI, undergoing a total of 686 capsulorraphies. The incidence of PSI treated surgically increased across the years of the study at a rate of 0.0293 per 100,000 person-years with an incidence in 2019-2020 greater than in 2016-2018 (p = 0.0151). Patients undergoing arthroscopic capsulorrhaphy were on average younger than those undergoing open capsulorrhaphy (p = 0.0021). Patients experienced a higher number of posterior instability events before open surgery compared to arthroscopic (p = 0.0274). The incidence of surgical treatment of PSI in the United States is steadily rising, with greater than 90% of cases being treated arthroscopically. Those undergoing arthroscopic posterior stabilization are both younger and face fewer instability events prior to surgery.

Patient Age and Surgical Intervention as Risk Factors for the Development of Osteoarthritis After Posterior Shoulder Instability: A Population-Based Study.

Background:Diagnosis and treatment of posterior shoulder instability (PSI) has improved with advances in imaging and surgical technique. However, the relationship between PSI and osteoarthritis (OA) remains unclear.Purpose:To evaluate a population-based cohort to (1) determine the rate of symptomatic OA, (2) identify patient characteristic risk factors for OA, and (3) evaluate the effect of posterior capsulolabral repair on OA progression.Study Design:Case-control study; Level of evidence, 3.Methods:After review of 324 patient records, we included 115 patients (14 female, 101 male) diagnosed with PSI between January 1994 and July 2012 with an average follow-up of 12.5 years (range, 5-23 years). Medical records were reviewed for patient characteristics, injury characteristics, surgical details (if any), and radiographic progression of OA. Kaplan-Meier survival was used to estimate survival free of OA; characteristics associated with OA progression were determined via univariate Cox regression models, and associated 95% CIs and hazard ratios (HRs) are presented.Results:Overall, 14% (16/115) of patients had radiographic progression of symptomatic glenohumeral arthritis, with 5-year survival of 88.3% (95% CI, 79.7%-97.3%). Older age at the time of instability diagnosis was associated with arthritis progression (10-year unit HR, 1.95; 95% CI, 1.26-3.03). Patients who underwent surgery demonstrated increased radiographic progression of OA (HR, 4.03; 95% CI, 1.23-13.23). There was a trend of increased OA in patients treated with labral debridement compared with repair despite lower baseline levels of OA; however, this difference was not statistically significant (P = .09).Conclusion:Symptomatic glenohumeral arthritis is not seen routinely in patients with PSI. Although uncommon, an age of at least 30 years at the time of diagnosis and surgical intervention were identified as risk factors for developing symptomatic arthritis at long-term follow-up.

Poster 145: Posterior Glenoid Osteotomy with Capsulolabral Repair Restores Force in a Critical Bone Loss Biomechanical Model

Objectives:Bone loss in posterior shoulder instability is an increasingly recognized clinical phenomenon. There is no widespread consensus on the surgical treatment of posterior shoulder instability with critical posterior glenoid bone loss. Here, we study the effect of opening posterior wedge osteotomy on resistance force of soft tissue repair alone in the setting of 20% critical bone loss.Methods:Native glenoid retroversion was measured on 9 cadavers. The humerus was potted in 90 degrees of forward flexion and 30 degrees of internal rotation relative to the scapula and a posterior dislocation was performed in order 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, (4) and 20% glenoid bone loss with posterior glenoid opening wedge osteotomy and posteroinferior capsulolabral repair. The resultant peak forces with 1 centimeter of posterior translation were measured. A one-way repeated-measures analysis of variance (RM-ANOVA) was used to compare mean force values.Results:Following the initial dislocation event, all shoulder had a resultant posterior capsulolabral 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 to the labral deficient group, p = 0.068. When 20% posterior bone loss was created, the posterior glenoid osteotomy with capsulolabral repair was significantly stronger than the posterior repair alone both with and without bone loss, p = 0.008 and p = 0.045, respectively.Conclusions:In the setting of critical posterior glenoid bone loss, an opening wedge posterior glenoid osteotomy with capsulolabral repair significantly improved resistance to posterior humeral translation compared to capsulolabral repair alone.

Paper 29: Return to Sport Testing vs Time-Based Clearance in Posterior Shoulder Instability

Objectives:Recurrent pain, instability and loss of function are challenging complications that can occur after arthroscopic treatment of posterior shoulder instability and SLAP tears in athletes. Many surgeons allow return to sport after a designated arbitrary postoperative time point. Recent evidence has demonstrated that a majority of athletes have residual strength and functional limitations at 6 months postoperatively – the time at which most time-based protocols allow full return to sport. Recent data has also been presented that patients undergoing arthroscopic Bankart repair who are required to meet objective return to sport testing criteria have a 4x lower rate of recurrent anterior instability than those who return based on time elapsed since surgery. Considering these findings, the purpose of this study is to investigate the use of a similar objective return to sport testing protocol on recurrence rates following arthroscopic surgery for posterior shoulder instability and SLAP tears. We hypothesized that patients who meet objective return to sport criteria would have a lower rate of reoperation and recurrence of symptoms compared to those who did not undergo the testing and were cleared to return based on time from surgery.Methods:Consecutive patients (Group 1) who underwent arthroscopic posterior shoulder stabilization surgery with or without SLAP repair by a single surgeon from 2016 to 2019, had a minimum of 1 year follow up, and completed functional and strength testing to evaluate readiness for return to sport were included in this retrospective case-controlled study. These patients were compared to a control group of historical consecutive cases (Group 2) from 2012-2016 who did not undergo return to sports testing and were cleared for sports after a minimum of 6 months following surgery. Failure was defined as recurrent symptoms of pain or instability requiring reoperation. Exclusion criteria were: patients undergoing isolated anterior stabilization procedures with or without concomitant SLAP tears, multidirectional instability, and open procedures. Chi-square, Fisher exact tests and two-tailed Students T-test were performed. Statistical significance was set at p<0.05.Results:There were 33 patients in Group 1 who underwent return to sport testing, and 91 patients in Group 2, the historical control. There were no differences between groups regarding sex (p=0.46), hand dominance (p=0.16), side affected (p= 0.69). The average age of Group 1 (20.8 +/- 4 yrs) was significantly younger than Group 2 (31.5 +/- 9.1 yrs, p< 0.00001). Patients who underwent return to sport criteria-based testing protocol had a rate of recurrent symptoms of pain or instability of 12.1% compared to 18.6% for those who did not (p= 0.43). Similarly, there were no reoperations for in Group 1, while three patients in group 2 (3.3%) underwent revision surgery for recurrent symptoms. This difference, however, did not reach statistical significance (p= 0.5633).Conclusions:In our cohort of young patients undergoing arthroscopic surgery for posterior shoulder instability, we detected no significant difference in reoperation rate and recurrence of symptoms between athletes who underwent objective return to sport testing and those who were released to sport on a time-based protocol. This may be related to an overall lower rate of reoperation in patients undergoing arthroscopic posterior stabilization or SLAP repairs in general compared to those undergoing arthroscopic anterior stabilization and differences in tolerance and presentation of recurrent posterior instability/SLAP tears versus anterior instability. It is possible that criteria-based return to sport testing prior to clearance to return to sport may be less critical for improving failure rates following arthroscopic posterior stabilization and SLAP repair than for anterior stabilization. Alternatively, given low reoperation rates overall, future studies investigating the role of return to sport testing after arthroscopic surgery for posterior shoulder instability and SLAP repairs may need to include more patients in order to detect differences related to the testing protocol. This study provides a basis upon which further studies, involving larger patient populations, may be conducted to elucidate any impact on functional scores and recurrence rates that may be associated with return-to-sport protocols based on functional testing rather than time since surgery.

Paper 11: Return to Sport Testing vs Time-Based Clearance in Posterior Shoulder Instability

Objectives:Recurrent pain, instability and loss of function is a challenging complication that can occur after arthroscopic treatment of posterior shoulder instability and SLAP tears in athletes. Many surgeons allow return to sport after a designated arbitrary postoperative time point. Recent evidence has demonstrated that a majority of athletes have residual strength and functional limitations at 6 months postoperatively – the time at which most time-based protocols allow full return to sport1. Recent data has also been presented that patients undergoing arthroscopic Bankart repair who are required to meet objective return to sport testing criteria have a 4x lower rate of recurrent anterior instability than those who return based on time elapsed since surgery2. Considering these findings, the purpose of this study is to investigate the use of a similar objective return to sport testing protocol on recurrence rates following arthroscopic surgery for posterior shoulder instability and SLAP tears. We hypothesized that patients who meet objective return to sport criteria would have a lower rate of reoperation and recurrence of symptoms compared to those who did not undergo the testing and were cleared to return based on time from surgery.Methods:Consecutive patients (Group 1) who underwent arthroscopic posterior shoulder stabilization surgery with or without SLAP repair by a single surgeon from 2016 to 2019, had a minimum of 1 year follow up, and completed functional and strength testing to evaluate readiness for return to sport were included in this retrospective case-controlled study. These patients were compared to a control group of historical consecutive cases (Group 2) from 2012-2016 who did not undergo return to sports testing and were cleared for sports after a minimum of 6 months following surgery. Failure was defined as recurrent symptoms of pain or instability requiring reoperation. Exclusion criteria were: patients undergoing isolated anterior stabilization procedures with or without concomitant SLAP tears, multidirectional instability, and open procedures. Chi-square, Fisher exact tests and two-tailed Students T-test were performed. Statistical significance was set at p<0.05.Results:There were 33 patients in Group 1 who underwent return to sport testing, and 90 patients in Group 2, the historical control. There were no differences between groups regarding sex (p=0.46), hand dominance (p=0.16), side affected (p= 0.69. The average age of Group 1 (20.8 +/- 4 yrs) was significantly younger than Group 2 (31.6 +/- 9.1 yrs, p< 0.00001). Patients who underwent return to sport criteria-based testing protocol had a rate of recurrent symptoms of pain or instability of 12.1% compared to 18.9% for those who did not (p= 0.43). Similarly, there were no reoperations for in Group 1, while three patients in group 2 (3.3%) underwent revision surgery for recurrent symptoms. This difference, however, did not reach statistical significance (p= 0.5633).Conclusions:In our cohort of young patients undergoing arthroscopic surgery for posterior shoulder instability, we detected no significant difference in reoperation rate and recurrence of symptoms between athletes who underwent objective return to sport testing and those who were released to sport on a time-based protocol. This may be related to an overall lower rate of reoperation in patients undergoing arthroscopic posterior stabilization or SLAP repairs in general compared to those undergoing arthroscopic anterior stabilization and differences in tolerance and presentation of recurrent posterior instability/SLAP tears versus anterior instability. It is possible that criteria-based return to sport testing prior to clearance to return to sport may be less critical for improving failure rates following arthroscopic posterior stabilization and SLAP repair than for anterior stabilization. Alternatively, given low reoperation rates overall, future studies investigating the role of return to sport testing after arthroscopic surgery for posterior shoulder instability and SLAP repairs may need to include more patients in order to detect differences related to the testing protocol. Objective functional testing may be a viable alternative to arbitrary, time-based criteria for returning to sport in patients who have undergone arthroscopic posterior shoulder stabilization and SLAP repairs.

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 Outcomes of Soft-Tissue Repair for Posterior Shoulder Instability Surgery.

This study aimed to assess the results after soft-tissue posterior instability surgery and address possible challenges during these operations. The databases of two tertiary hospitals were reviewed to identify patients treated for posterior shoulder instability between 2000 and 2015. Out of 198 treated patients, 19 cases underwent surgery with a mean follow-up of 35 months. Chart review was performed to obtain recurrence rates, revision rates, return to sport, persistent pain, subjective instability, subjective feeling of being better, complications, and range of motion after operative treatment of posterior shoulder instability. These outcomes were compared using the Fisher's exact and Mann-Whitney U tests. After surgery, 6 (32%) patients had a recurrent subluxation, and 11 (58%) cases had persistent pain; moreover, 5 (26%) patients had a persistent feeling of instability, and 10 (53%) cases did not feel improvement after the operation. Furthermore, 10 (53%) patients required a revision, and there were 7 (37%) cases with a complication. Postoperatively, 75% of the patients had a full forward flexion, and 93% of the cases had full internal rotation; however, 64% of them had restrictions in external rotation. There is a high rate of recurrent instability, need for revision, and complications after soft-tissue posterior instability surgery. Postoperative external rotation was impaired in most patients. Patients should be informed about these unsatisfactory results.

Long-term results after posterior open glenoid wedge osteotomy for posterior shoulder instability associated with excessive glenoid retroversion.

Treatment of posterior shoulder instability (PSI) associated with excessive glenoid retroversion is a rare, challenging problem in shoulder surgery. One proposed technique is posterior open wedge glenoid osteotomy to correct excessive glenoid retroversion as described by Scott. However, this operation is rarely performed, and limited long-term outcomes using this approach are available. The goal of this study was to analyze the long-term outcomes of posterior open wedge glenoid osteotomy for PSI associated with excessive glenoid retroversion. Six consecutive patients (7 shoulders) with a mean age of 24 years (range 19-34) were treated with posterior open wedge glenoid osteotomy for PSI associated with a glenoid retroversion greater than 15° and followed up clinically and radiographically at a mean age of 15 years (range 10-19). Recurrent, symptomatic PSI was observed in 6 of 7 shoulders (86%). One necessitated revision with a posterior (iliac crest) bone block procedure and was rated as a failure and excluded from functional analysis. One patient rated his result as excellent, 3 as good, 1 as fair, and 1 as unsatisfactory. Mean relative Constant Score (CS%) was unchanged from preoperation to final follow-up (CS% = 72%) and pain did not significantly decrease (Constant Score = 7-10 points; P = .969). The mean Subjective Shoulder Value (SSV) improved postoperatively, but with 6 patients the improvement did not reach statistical significance (SSV = 42%-67%, P = .053) and the total Western Ontario Shoulder Instability Index averaged 30% at the final follow-up. Mean glenoid retroversion of all 7 shoulders was corrected from 20° (range 16°-26°) to 3° (range -3° to +8°) (P = .018). In the 5 shoulders with preoperative static posterior subluxation of the humeral head, the humeral head was not recentered. All 7 shoulders showed progression of glenoid arthritic changes. Posterior open wedge glenoid osteotomy for PSI associated with excessive glenoid retroversion neither reliably restored shoulder stability nor recentered the joint or prevent progression of osteoarthritis. Alternative treatments for PSI associated with excessive glenoid retroversion have to be developed and evaluated.

Indications and outcomes of glenoid osteotomy for posterior shoulder instability: a systematic review.

There is limited evidence examining glenoid osteotomy as a treatment for posterior shoulder instability. A search of Medline, Embase, PubMed and Cochrane Central Register of Controlled Trials was conducted from the date of origin to 28th November 2019. Nine out of 3,408 retrieved studies met the inclusion criteria and quality was assessed using the Methodological Index for Non-randomized Studies tool. In 356 shoulders, the main indication for osteotomy was excessive glenoid retroversion (greater than or equal to approximately -10°). The mean preoperative glenoid version was -15° (range, -35° to -5°). Post-operatively, the mean glenoid version was -6° (range, -28° to 13°) and an average correction of 10° (range, -1° to 30°) was observed. Range of motion increased significantly in most studies and all standardized outcome scores (Rowe, Constant-Murley, Oxford instability, Japan Shoulder Society Shoulder Instability Scoring and mean shoulder value) improved significantly with high rates of patient satisfaction (85%). A high complication rate (34%, n = 120) was reported post-surgery, with frequent cases of persistent instability (20%, n = 68) and fractures (e.g., glenoid neck and acromion) (4%, n = 12). However, the revision rate was low (0.6%, n = 2). Glenoid osteotomy is an appropriate treatment for posterior shoulder instability secondary to excessive glenoid retroversion. However, the high rate of persistent instability should be considered when making treatment decisions.Level of Evidence: Systematic review; Level 4.

Posterior glenoid bone block transfer for posterior shoulder instability: a systematic review.

The purpose of this study is to systematically review the literature and evaluate patient-reported outcomes and complication/revision rates of bone block augmentation in the treatment of posterior shoulder instability (PSI). PubMed was searched according to PRIMSA guidelines to find clinical studies evaluating patient-reported outcomes, revision, and complication rates in posterior bone block for PSI. A literature search of MEDLINE, EMBASE, and the Cochrane Library was performed based on the PRISMA guidelines. Clinical studies reporting on the complications following posterior bone block were included. Overall, 11 studies (level of evidence [LOE] III: 2, LOE IV: 9) met inclusion criteria, with 225 shoulders. Recurrent instability after the posterior bone block was found to be 9.8%. The overall complication rate was 13.8%, with 0.89% having graft complications, 11.1% having hardware complications, 0.4% having wound complications, 0.4% having nerve complications, and 0.89% having other complications. Residual pain was found in 11.6% of shoulders operated on. Patient-reported outcomes were evaluated most commonly by Rowe (81.4%), Constant (84.6%), and Walch-Duplay scores (81.6%). There is a moderate rate of recurrence following posterior bone block for PSI. However, the patient-reported outcomes are high despite there being commonly reported persistent shoulder pain postoperatively.

Current diagnosis and treatment of posterior shoulder instability

The incidence of posterior instability of shoulder joint was significantly lower than that of anterior instability, but the clinical diagnosis and treatment was difficult, and the misdiagnosis and missed diagnosis rate were high. Its etiology, clinical manifestation and treatment strategy are totally different from the anterior instability. Therefore, the deep understanding of the anatomical structure around the shoulder joint, the mastery of the examination method, and the classification of the shoulder instability based on the anatomy and injury mode are of great importance to improve the accuracy of diagnosis. CT three-dimensional reconstruction is helpful to evaluate the defect of humeral head and glenoid bone, and MRA is helpful for the accurate diagnosis of posterior glenoid lip and joint capsule. The treatment was divided into conservative treatment and surgical treatment. Conservative treatment is recommended for muscular instability. Surgical treatment is recommended for traumatic and dysplastic instability. Different operative methods should be performed according to the injury of glenoid side or humeral head side. According to the condition of bone defect, soft tissue operation, bone grafting or osteotomy were performed to reconstruct the posterior stable structure of the glenoid injury; according to the area of the anterior bone defect, bone grafting or subscapular muscle packing were performed to the head of humerus defect. The former has the advantages of short learning curve and firm fixation, while the latter has the advantages of minimally invasive operation and the ability to observe the lesions from multiple angles and accurately control the location of bone masses. This paper summarizes the above problems.

Posterior Glenoid Reconstruction Using a Distal Tibial Allograft

Posterior shoulder instability is increasingly recognized and diagnosed in young athletes. These patients often present with vague shoulder pain rather than the frank instability commonly seen with anterior instability. Three common causes of posterior shoulder instability are congenital retroversion, a single traumatic event, or repetitive microtrauma with erosive effects. The critical determination when deciding on the appropriate treatment of posterior shoulder instability is the presence and degree of glenoid bone loss. In patients without bone loss, arthroscopic procedures have a high success rate with a failure rate of less than 10% and an 89% return-to-sport rate. The determination of the critical amount of bone loss that would permit an arthroscopic procedure is controversial, but recent reports that attempt to quantify the critical bone loss value posteriorly have ranged from 13.5% to 20%. This Technical Note describes our preferred method of open surgical treatment of posterior shoulder instability with posterior glenoid bone loss using an intra-articular distal tibial allograft.