Medial wear of the polyethylene component associated with heterotopic ossification after reverse shoulder arthroplasty.

We performed an RSA (Anatomical Shoulder (TM) Inverse/Reverse; Zimmer) on a 73-year-old, right-handed man who had radiographic evidence of an irreparable rotator cuff tear and early rotator cuff arthropathy. The patient was immobilized in a sling for 6 weeks postoperatively. The sling was removed 3 times daily for shoulder exercises. At 4 weeks postoperatively, the patient reported good pain relief and demonstrated 90 degrees of active forward elevation and abduction. Early postoperative radiographs showed no evidence of periarticular calcification (Fig. 1). Eight weeks postoperatively, the patient presented to our clinic with pain after hearing a “crack” in his right shoulder. Radiographs revealed disassociation of the glenoid head from the glenoid fixation and the development of significant periarticular heterotopic ossification inferior and medial to the glenoid (Fig. 2). We performed revision surgery, which included removal of the humeral cup to reconnect the glenoid head. The humeral cup inlay contained significant wear of the polyethylene medially. Intraoperative trial reduction with a new inlay revealed that, although the implant was well clear of the glenoid neck and the lateral border of the scapula when the arm was adducted, the humeral cup was rubbing Case Note Note de cas