前方進入法による人工股関節置換術施行例の術前術後の外転筋力の定量的評価

Hip Abductor Strength Recovery Following Total Hip Arthroplasty through Direct Anterior Approach

　前方進入法による人工股関節置換術（THA）を施行し，術前後での股関節外転筋力を定量的に評価した．対象は2005年5月から2006年8月までに当院で施行した初回のTHA 152関節中，術前，術後1週，術後1カ月，術後3カ月に両側の股関節外転筋力を測定し得た症例である．筋力の推移は，術前0.53，術後1週0.49，術後1カ月0.66，術後3カ月0.83（Nm/kg）で，術後1週で有意に低下せず，術後1カ月から有意に増加に転じた．また，対健側比では術後3カ月で同等まで回復した．これは，本法の低侵襲性を定量的に裏付けた結果と考えた．

　The purpose of this study is to evaluate the recovery of the hip abductor muscle strength of minimally invasive total hip arthroplasty (THA) through the direct anterior approach. We measured the isometoric abductor muscle strength of 152 THAs between May in 2005 and August in 2006 at the time of preoperative day, 1 week, 1 month and 3 months postoperatively. The strength of the hip abductor was 0.53 preoperatively, 0.49 at l week, 0.66 at 1 month, 0.83 (Nm/kg) at 3 month postoperatively. The hip abductor strength significantly increased at 1 month and at 3 months postoperatively without significant decrease at 1 week postoperatively. Comparing with the uninvolved hip, the strength of the involved hip recovered at the same level of the uninvolved hip at 3 month postoperatively. This study demonstrated that the direct anterior approach completely preserved the strength of the hip abductor.