摘要：Purpose To quantify the effects of the systematic internal and external femoral component rotations and tibial slope on the medial and lateral tibiofemoral gaps in total knee endoprostheses. Methods Nineteen knee cadaver specimens with an intact ligament apparatus were fixed in a custom frame, facilitating physiological flexion motion. Virtual total knee arthroplasty was performed on three-dimensional models obtained from computed tomography scans (0° and 90° flexions) with systematically altered femur rotations and tibial slopes. Results Both the femur rotation and the tibial slope influenced the medial and lateral tibiofemoral flexion gaps ( p < 0.001), and the effects differed between the medial and lateral sides ( p < 0.001). The medial tibiofemoral flexion gap increased by 2.90 ± 0.34 mm and decreased by 2.66 ± 0.26 mm for 7° external and internal femur component rotations, respectively (both with p < 0.001). The lateral tibiofemoral flexion gap decreased by 3.11 ± 0.31 mm and increased by 3.29 ± 0.33 mm for 7° external and internal femur component rotations, respectively (both with p < 0.001). Conclusion For established surgical methods, we recommend a neutral femur rotation for a 0° tibial slope and a 3° external femur rotation for a tibial slope of 9–10°. The translational potential of this research shows that while the rotation of the femoral component in extension has no effect on the gap size, owing to the axis of rotation being perpendicular to the gap, for a 90° flexion, we not only observe differences in the gap size between the medial and lateral but also unequal differences on either side depending on the inward or outward rotation. The main reason for this is the position of the axis of rotation, which is not precisely half way between the lateral and medial contact points. The results show that rotation of the femoral component always creates an unbalanced flexion gap..
关键词：Physiological knee motion ; Surgical technique ; Total knee arthroplasty
