三次元下肢アライメント測定システムを用いた人工膝関節コンポーネントの設置位置評価

Three-dimensional Assessment of Component Alignment after Total Knee Arthroplasty by Use of KneeCAS System

　独自に開発した三次元下肢アライメント測定システムによる人工膝関節置換術（TKA）のコンポーネント設置位置評価法とその概念を紹介し，実際にTKAを施行した35膝での評価を行うことでその有用性を検討した．三次元的に設定した一定の尺度で評価すると，大腿骨，脛骨両コンポーネントとも内外反角度は良好だったが，目標設置角度が一定でない屈曲伸展角度や，術中の制御が困難な回旋角度はばらつきが多かった．術前後の顆部形状変化も含め，従来の二次元的評価では検討不可能な項目も多く，今後のTKAにおけるさらなる科学的解析に有用であるものと考えられた．

　A 3-dimensional (3D) assessment system for lower extremity alignment was developed. In this study the system was applied to an analysis of the postoperative 3D component alignment of 35 knees, and its validity was assessed. The results showed that varus-valgus alignment was relatively well converged, while flexion-extension and rotational alignment were relatively deviated. Use of this system enabled highly accurate evaluation of 3D orientations, including rotational alignment, which has been impossible to evaluate by means of plain radiographs. These 3D system and standard criteria for evaluation of 3D component alignment and bone geometry are absolutely necessary for more scientific development of an ideal TKA procedure and design.