Is prophylaxis for heterotopic ossification with radiation therapy after THR associated with early loosening or carcinogenesis?

Heterotopic ossification may develop after major hip surgeries, thus preventive strategies including radiation therapy and non steroid anti-inflammatory drugs are commonly employed. There are certain concerns regarding the effects of radiation therapy on implant loosening and carcinogenesis. Our study aims to evaluate whether radiation therapy results in implant loosening or radiation-induced tumours in the long term.

This was a prospective study including 97 high-risk patients for heterotopic ossification who underwent total hip arthroplasty. Patients were divided into 2 groups and received either a combination of radiation therapy and indomethacin (Group A), or indomethacin alone (Group B). Evaluated outcomes included implant loosening or development of radiation-induced tumours during the follow-up period.

The follow-up period of the study was 10 years. Group A consisted of 50 patients, while Group B consisted of 47 patients. 3 patients died during the follow-up. There were 2 cases of implant loosening, 1 from each of the 2 groups at 9 and 10 years after surgery respectively; thus, no statistically significant difference regarding implant loosening was found (p < 0.05). During the follow-up period no cases of radiation-induced tumours were identified.

Our results are consistent with those of other studies supporting the safety of radiation therapy as a preventive strategy for heterotopic ossification following major surgeries in high risk patients. Further studies with even longer follow-up may be required to definitely exclude the possibility of adverse outcomes linked with radiation therapy.