Posterior shoulder dislocations are still a challenge for the treating physician. The mechanisms of trauma are varied, which complicates diagnosis. Missed or delayed diagnosis and treatment can have serious deleterious effects on shoulder function. Here we present the case of a young patient who suffered a direct trauma on the left shoulder stump, resulting in posterior glenohumeral dislocation, irreducibly orthopedic. Preoperative CT scan and surgical exploration, performed by a delto-pectoral approach, showed the presence of “Hill-Sachs lesion” not exceeding 15% of the humeral circumference, and coming to stop against the posterior border of the glenoid cavity, without ligamentous or capsular interposition. The shoulder was stable after reduction. The surgical procedure was completed by a capsulorraphy, without the need to fill the humeral defect