Posterior Instability of the Shoulder: A Systematic Review and Meta-analysis of Clinical Outcomes

Background: To date, there are no reports in the literature of a systematic review and meta-analysis for posterior instability of the shoulder. Purpose: The primary objective was to systematically capture, critically evaluate, and perform a meta-analysis of all available literature on arthroscopic clinical outcomes to provide insight and clinical recommendations for unilateral posterior shoulder instability. The secondary objective was to use the same means to assess clinical outcome literature for open treatment, of which a subset of highly reported outcome measures were used to determine superiority of arthroscopic versus open procedures for unilateral posterior shoulder. Study Design: Systematic review, meta-analysis. Methods: A systematic search to obtain every available, published, level of evidence study reporting patient data for unidirectional posterior shoulder instability was performed by use of the Cochrane Database of Systematic Reviews, PubMed/Medline database, manual searches of high impact factor journals and conference proceedings, and secondary references appraised for studies meeting inclusion criteria. Results: The systematic search captured a total of 1035 publications. After initial exclusion criteria were applied, 607 abstracts were assessed for eligibility. Full-text articles were obtained for 324 articles, and a total of 53 unique publications (27 arthroscopic studies, 26 open studies) reporting clinical outcomes for unidirectional posterior shoulder instability met inclusion criteria and were included in the systematic review and meta-analysis. Conclusion: Well-defined and uniform shoulder outcome measures to assess posterior shoulder instability are lacking throughout the literature. However, arthroscopic procedures are shown to be an effective and reliable treatment for unidirectional posterior glenohumeral instability with respect to outcome scores, patient satisfaction, and return to play. Despite similar results of outcome measures to the overall athletic population, throwing athletes are less likely to return to their preinjury levels of sport compared with contact athletes or the overall athletic population. Evidence also indicates that arthroscopic stabilization procedures using suture anchors result in fewer recurrences and revisions than anchorless repairs in young adults engaging in highly demanding physical activity. Furthermore, the literature suggests that patients treated arthroscopically have superior outcomes compared with patients who undergo open procedures with respect to stability, recurrence of instability, patient satisfaction, return to sport, and return to previous level of play.