Surgery trends for osteonecrosis of the femoral head: a fifteen-year multi-centre study in Japan.

Purpose: The most appropriate procedure and at what type and stage of osteonecrosis of the femoral head (ONFH) these procedures had been argued. We attempted to clarify the trend in surgical operations with respect to the age of patients, type classification, and stage of ONFH over a period of 15 years by using the multi-center sentinel monitoring system in Japan.
Methods: We evaluated the hips of 3844 patients using this system in three phases of every five  years from 2003 to 2017. We classified the surgical procedures as osteotomy (OT), hemiarthroplasty (Hemi), and total hip arthroplasty (THA). We assessed the trend in age, type classification, and stage of ONFH over three time periods; "early," and the "late." We calculated the proportion of surgeries for ONFH in each period. We used the Cochran-Armitage test to evaluate trends in proportion of two levels of characteristics across three time periods.
Results: The proportion of younger patients significantly decreased. The proportion of OT and Hemi decreased over time, while the proportion of THA increased. The proportion of patients with types C1 and C2 who underwent OT and Hemi decreased over time. In contrast, that of THA increased. The proportion of patients who underwent OT and Hemi significantly decreased; the proportion of patients who underwent THA significantly increased over time at all stages.
Conclusions: In Japan, the younger patients underwent surgery for ONFH decreased. The patients who underwent OT and Hemi for ONFH decreased, while that of THA increased over time.