Incidence of heterotopic ossification and effects of various prophylactic methods after hip resurfacing

A retrospective analysis of 1000 hips in 838 patients was conducted to determine the efficacy of alterations made throughout the series to the prophylactic protocol used to minimize the incidence of heterotopic ossification (HO) after hip resurfacing.

Four groups were determined following the initiation of these changes. Initially, the patients received indomethacin and 1000 milliliters of both saline and duobiotic (group 1). In group 2, a single pre-operative 700 cGy radiotherapy session was added for males undergoing one-stage bilateral procedures or the second stage of a two-stage procedure when HO had formed on the first hip. In group 3, the volume of saline used to clean the wound after implantation was increased from 1000 to 2000 milliliters, while the 1000 milliliters of duobiotic remained throughout the series. Finally, the use of a plastic drape was added to collect bone debris during the reaming of the femoral head in group 4. Chi-square analyses were conducted between groups to identify significant decreases in the prevalence of HO.

Group 3 showed a reduction in incidence of all HO grades combined, and severe HO only compared with group 2 (p = 0.003 and p = 0.007, respectively). A decrease in severe HO incidence was observed between group 1 and group 2 in males who underwent bilateral surgery (p = 0.048). In addition, there was a significant decrease in the incidence of both all HO grades (p = 0.0001) and severe HO (p = 0.029) between groups 1 and 4. In contrast to most studies that have assessed the individual effect of prophylactic methods in a single protocol, the present study confirmed the effectiveness of combining indomethacin and radiation therapy in high-risk patients, as well as copious pulse lavage of the wound in reducing the incidence of HO. The use of the plastic drape did not confer any additional gain.