TREATMENT OF CYSTS OF THE ACROMIOCLAVICULAR JOINT WITH SHOULDER HEMIARTHROPLASTY

A chronic cyst overlying the acromioclavicular joint was managed in fo ur patients, between July 1988 and September 1991. All patients had ha d previous unsuccessful aspiration and excision of the cyst with recur rence. Each cyst was associated with a chronic, massive defect of the rotator cuff; superior migration of the humeral head; and degenerative osteoarthrosis of the glenohumeral joint. All patients had complained of pain and limitation of motion (mean forward elevation, 95 degrees; mean external rotation, 20 degrees; and mean internal rotation, to th e spinous process of the second lumbar vertebra). All procedures consi sted of a large-humeral head hemiarthroplasty, with no operative treat ment directed at the cyst or the acromioclavicular joint. At an averag e of twenty-seven months (range, fifteen to thirty-six months) after t he operation, the patients were all pain-free and had not had a recurr ence of the cyst. The average postoperative range of motion was 130 de grees of forward elevation, 30 degrees of external rotation, and inter nal rotation to the spinous process of the first lumbar vertebra.