An unusual complication of the Mackenzie approach for a Copeland hemiarthroplasty.

We report the case of a patient with end-stage osteoarthritis who received a successful Copeland resurfacing hemiarthroplasty through a Mackenzie anterosuperior approach, which involves taking the anterior portion of the deltoid attachment from the acromion along with an osteo-periosteal sleeve. The patient went on to develop severe subacromial impingement symptoms 4 months postoperatively. X-rays revealed a large anteroinferior acromial osteophyte that had not been present preoperatively and was deemed to represent a malunited osteo-periosteal sleeve from the Mackenzie approach.