We experienced a case of locked posterior fracture-dislocation of the shoulder. A 38-year-old man suffered posterior fracture-dislocation of his right shoulder associated with anatomical neck fracture of the humerus by a traffic accident. The fragment was locked at the posterior edge of the glenoid, so that a closed reduction had failed. He was treated by an open reduction, and the fragement was fixed by 3 cancellous screws. At the final follow up, his shoulder was stable and showed no instability. MRI scans showed small region of osteonecrosis in the cephalic portion of the antero-medial part of the humerus, but X-rays showed no deformity of articular surface or arthritic changes. The ROM was slightly limited, but the patient returned to work with no pain, and the JOA score was 85 points.
Posterior fracture-dislocation of the shoulder is very rare and the highly displaced fragments often prevent a closed reduction. In these locked cases, closed reduction are not usually atraumatic and the open anterior reduction may be better. Recently, some reports showed arthroscopically assisted reduction was useful in the point that it enabled the evaluation of torn posterior capsule or labrum immediately after the successful reduction. It is controversial if these Reverse Bankart lesions should be repaired at the initial reduction, but this method is less invasive and worth trying. On the contrary, an open reduction have the risk of soft tissue injury, which may lead to severe contracture and late segmental collapse of the humeral head. In this case, the area of the osteonecrosis was limited and the articular surface was preserved, which revealed satisfying results. We should not hesitate the open reduction in irreducible cases.
