Pyarthrosis simulating ruptured rotator cuff syndrome.

A 50-year-old black man was admitted with a diagnosis of a ruptured rotator cuff syndrome two weeks after an injury to the right shoulder and treatment by intra-articular steroid injection. At operation pus and necrotic debris were found in the shoulder joint, but the rotator cuff was anatomically intact. Surgical debridement, irrigation, and intravenous antibiotics resulted in good recovery with satisfactory function. The pyarthrosis apparently resulted from the preoperative intra-articular injection.