Heterotopic ossification after Total Knee Replacement. Is it an issue?

Abstract

Introduction: Heterotopic ossification after total knee arthroplasty is a less frequently studied topic in contrast to after total hip arthroplasty. Its incidence in the western literature ranged from 1 to 42% but the incidence in a Chinese population is largely unknown. The significance and effects on the outcome of the surgery also remain controversial. Materials and Methods: We retrospectively reviewed all total knee arthroplasties performed in a local hospital from January 2009 to December 2010. Revision surgeries were excluded. The patients were assessed clinically on follow-up for range of motion of the knee and the most recent postoperative X-rays were studied for the presence of heterotopic ossification. Results: A total of 413 primary total knee arthroplasties were performed during the study period on 371 patients. The mean follow-up time was 44 months. The incidence of heterotopic ossification was 15.7%. The majority of which were located at the suprapatellar pouch (35%) or along the medial gutter (42%). Increase in size of the heterotopic ossification was not associated with reduced gains in the range of motion of the knee. Discussion and Conclusion: Heterotopic ossification after total knee arthroplasty is not an uncommon condition in the Chinese population. It was previously thought to occur mainly at the suprapatellar pouch, but our study showed that the medial gutter was the most common location. However, its presence did not appear to impact negatively on the range of motion of the knee on follow-up.