骨温存型MIS-THAの治療経験

―表面置換型人工股関節を用いて―

抄録

The purpose of the present study is to clarify the effectiveness of bone preservative MIS-THA using resurfacing hip prostheses. Between April 2005 and September 2006, we performed twenty bone preservative MIS-THAs by resurfacing hip prostheses (Cormet: Corin, Cirencester, UK) . The average age at operation was 63 years. The average BMI was 22.8 kg/m². The average preoperative functional hip score was 41 points. The primary diagnosis in all cases was secondary osteoarthritis due to hip dysplasia. Seventeen hips were classified as first degree by Crowe's classification of hip dislocation, and three hips were second degree. We evaluated operative invasion, implant alignment and functional recovery. The average operation time was 128 minutes, and the average intra- and post-operative blood loss volumes were respectively 524 and 581 ml. All cups were implanted within the safe zone of Lewinnek. Varus head alignment was seen in one hip. Postoperative dislocation was not observed in any case. The average required time until walking with a single cane, standing on the operated leg alone, and negative Tredelenburg sign were respectively 13 days, 20 days and 20 days. Bone preservative MIS-THA by resurfacing hip prosthesis was effective in reducing invasion, in femoral head preservation, and in reduced frequency of dislocation.