Heterotopic ossification after total hip replacement

Heterotopic bone formation occurs in up to 70% of patients who have undergone a total hip arthroplasty. Although histologically similar to mature skeletal bone, the ectopic tissue limits postoperative motion and causes pain in 2% to 4% of patients. The ossification is classified and graded according to radiographic appearance. Males with bilateral hypertrophic osteoarthritis who have had prior hip surgery are at high risk. Prophylaxis with Indocin or low-dose irradiation treatment is effective. Excision and irradiation therapy can treat established bony bridges.