Posterior dislocation of the shoulder: recommendations for a classification.

Posterior dislocation of the should is rare, constituting only 2.1% of all shoulder dislocations. The mechanisms of injury may be due to direct or indirect forces, and constitutional predisposing factors also play a role. Anatomically, 97.5% of dislocations are subacromial. Three hundred articles published in the international literature concerning posterior shoulder dislocation and subluxation were reviewed and a classification determined by the underlying aetiology was developed. On this basis dislocations and subluxations may be traumatic or atraumatic, primary and recurrent; recurrent cases of voluntary dislocation are considered separately. In addition, a follow-up assessment score weighted towards stability of the shoulder after treatment is detailed.