Heterotopic ossification after acromioplasty and distal clavicle resection.

A retrospective review of acromioplasty and distal clavicle resections disclosed 40 cases in which postoperative ectopic bone formation caused recurrent shoulder impingement or acromioclavicular joint pain. Symptomatic lesions either encroached on the supraspinatus outlet or were located in the acromioclavicular interval and were large in size. The incidence of symptomatic heterotopic ossification occurring after acromioplasty or distal clavicle excision was 3.2% and was disproportionately seen in patients with chronic pulmonary diseases (p < 0.05). Heterotopic bone formation could not be correlated with the method of bone resection and occurred after both open and arthroscopic procedures. No evidence of bone remnants or calcific deposits was seen in 17 patients in whom postoperative radiographs were taken within 8 weeks of the operation. It thus appeared that the heterotopic bone formed de novo after the procedure. Twenty patients had repeat shoulder surgery to ameliorate symptoms; four of these had a second recurrence of postoperative heterotopic bone formation. Three of the four required a third procedure and had effective prophylaxis against heterotopic ossification. It is suggested that patients at risk (e.g., with a profile of hypertrophic pulmonary osteoarthropathy or active spondylitic arthropathy) be treated with prophylaxis for heterotopic ossification after acromioplasty and distal clavicle resections.