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.