Diagnosis and Therapeutic options for posterior shoulder dislocation

Background: Posterior shoulder instability is a rare clinical entity, representing 2% to 5% of all shoulder instability cases. Management is complicated by diverse clinical presentations, varying anatomical lesions, and the presence of predisposing factors such as glenoid retroversion or hypoplasia.

Objective: This study evaluates the outcomes of a multicenter symposium involving 188 patients to identify prognostic factors and refine management algorithms for involuntary, voluntary, and painful posterior instability.

Key Points: Involuntary instability associated with anatomical lesions demonstrated superior outcomes with surgical intervention compared to functional rehabilitation. Arthroscopic capsulolabral repair, particularly when combining labral reattachment with capsular shift, yielded high satisfaction rates (80%) and successful return to competitive sports. While posterior bone blocks are indicated for significant glenoid deficiency, they showed no statistical superiority over soft tissue repair in cases without major bone loss. Conversely, purely voluntary instability remains a contraindication for surgery, requiring neuromuscular reprogramming. In "voluntary-to-involuntary" cases triggered by trauma, surgery is justified, though outcomes are less predictable than in purely involuntary forms. The "unstable painful shoulder" (UPS) variant presents diagnostic challenges; preoperative glenoid cartilage damage in these patients is a significant negative prognostic factor for pain relief.

Conclusion: Surgical success in posterior instability is highly correlated with the presence of discrete anatomical lesions and the absence of chondral damage or generalized hyperlaxity. Arthroscopic labral repair is the preferred treatment for young athletes with involuntary instability, while bone blocks should be reserved for substantial glenoid rim defects.