Heterotopic bone formation: irradiation of high risk patients

The Royal Marsden Hospital has adopted a policy for patient selection for the use of adjuvant radiotherapy to prevent heterotopic new bone formation (HTBF) limited to those at greater than 50% risk. The treatment protocol is 7 Gy post-operative megavoltage radiotherapy at mid-plane, in one fraction, given within 72 h of surgery. Since the introduction of this protocol in 1993, 26 joints have been treated in 25 patients. The majority of cases were young people with acetabular fractures resulting from road traffic accidents, often alcohol related. Follow-up studies in this group of patients has proved difficult, as many fail to attend for follow up, and others have moved out of the catchment area. Of the 14 cases for which follow-up data is available, 13 remain fully mobile. One has not mobilized since the time of treatment and continues to use crutches. There is one case of recurrent HTBF seen on X-ray after 8 months, but the joint was mobile. By 5 years, all cases have failed to attend for follow-up. The true long-term risks of this treatment policy may not be known for 30 years. The failure of patients to attend even short-term follow-up is a potential problem for clinical oncologists.