臼蓋形成不全股に対するソケットの設置位置の検討

Outcomes of Acetabular Component Fixation after Total Hip Arthroplasty in Developmental Dysplasia of the Hip

　2008年6月から2012年6月までに臼蓋形成不全股(Crowe分類2～4型)に対して初回人工股関節全置換術(THA)を施行した193関節を対象とし，ソケットの設置位置を検討した．原臼位に近いほど，臼蓋母床のソケットの被覆度を示すカップCE角は減少したが，適切な内方化と前後方へのプレスフィットおよびスクリュー固定により初期固定が得られた．最終観察時，弛みを認めた症例はなかった．カップCE角が0°以下(－27.6°～28.4°)でも，プレスフィットとスクリュー固定の併用で初期固定が得られることが示唆された．

　The cases of 193 patients with Crowe type 2-4 developmental dysplasia of the hip (DDH) who underwent primary THA between 2008 and 2012 were retrospectively reviewed.　We evaluated cup position in the true acetabulum, cup center-edge (CE) angle, and prosthesis survival.　The results showed that in 187 cases the cup was positioned in the true acetabulum, and in 6 cases it was positioned above the true acetabulum.　The mean cup-CE angle was 3.4 ± 9.2° (-26.6―28.4), and it was under 0° in 73 joints, but all were positioned in the true acetabulum.　The survival rate in terms of both the loosening and revision end points was 100%.　The superolateral bone defect increased and bony coverage of the cup was reduced when the cup was placed in the true acetabulum of THA patients with DDH.　Even though the cup-CE angle was ＜0°, the results suggest strong fixation of the press-fit cups and screw-fixed cups over the short term.