Heterotopic ossification after primary shoulder arthroplasty.

We have assessed the incidence of heterotopic ossification (HO) after primary shoulder joint replacement in 126 shoulders; 58 patients had hemiarthroplasty, and 68 had total shoulder joint replacement. HO developed to a minor extent in 15% of patients (19/126). There was no statistical difference between hemiarthroplasty or total shoulder replacement or between male and female patients. Patients with cuff tear arthropathy were the only group with an increased risk (36.4% [4/11]) of having HO develop. In patients with osteoarthritis, fractures, or rheumatoid arthritis, HO occurred in less than 14.5% (15/115). Nonsteroidal anti-inflammatory drugs (NSAIDs) did not appear to have any effect on HO as in hip replacement, as HO developed in 15.15% of patients having NSAIDs postoperatively and in 15.05% of patients without NSAIDs. Prophylaxis of HO with NSAIDs seems only to be indicated in patients with cuff tear arthropathy.