Heterotopic ossification around the hip in spinal cord-injured patients. A long-term follow-up study

Twenty patients with spinal cord injury complicated by ossification around the hip were followed for eighteen months or more. The bone scan, roentgenogram, level of alkaline phosphatase, and range of hip motion of each patient were analyzed. The average follow-up was forty months. The heterotopic ossification usually did not mature until after one and one-half years. The roentgenograms were of no value in judging its maturity. The bone scan correlated well with the results of the alkaline phosphatase testing in judging maturity of the ossification. We concluded that before operative resection, a patient should have a normal level of alkaline phosphatase, decreasing activity on the bone scans, and a restriction of motion to less than 50 degrees of hip flexion.