Shoulder dislocation (instability)

Posterior shoulder dislocations are rare, accounting for less than 5% of all shoulder dislocations. They often result from seizures, electric shocks, or direct trauma causing internal rotation and adduction of the arm. Due to subtle clinical signs, they are frequently missed in initial assessments. Imaging with axillary or scapular Y views is crucial for accurate diagnosis. Management depends on the chronicity, associated injuries (e.g., reverse Hill-Sachs lesion), and joint stability post-reduction, size of the Critical Fragment. Early recognition and appropriate treatment such as Modifies McLaughlin’s procedure are essential to restore joint function and prevent complications like arthritis or avascular necrosis.

Closed reduction is the initial treatment approach for acute posterior dislocations, typically under sedation or anesthesia. Gentle traction with gradual external rotation is used. If the dislocation is recent and uncomplicated, closed reduction usually succeeds. However, if the joint is locked, there's a large reverse Hill-Sachs lesion, or it's a chronic dislocation, open reduction becomes necessary. Open reduction allows direct visualization, removal of interposed tissue, and concurrent repair of associated injuries. Post-reduction immobilization in external rotation may be needed. Failure to achieve a stable, congruent reduction may require additional procedures like bone grafting or tendon transfers.

The McLaughlin procedure is indicated in posterior dislocations with a large reverse Hill-Sachs lesion (impaction of the anteromedial humeral head). It involves transferring the subscapularis tendon into the humeral head defect to prevent engagement with the glenoid. This fills the defect and restores stability. A modified version may include transfer of the lesser tuberosity with the attached subscapularis (Modified McLaughlin). This procedure is typically performed when the lesion involves 20–40% of the articular surface. It is effective in restoring joint function and preventing recurrent dislocation. Larger defects may require bone grafting or arthroplasty if chronic or irreparable.