Stöbe Claudio, Hoechel Sebastian, Müller-Gerbl Magdalena, Nowakowski Andrej M
Department of Orthopedics, Stephanshorn, Brauerstrasse 95, 9016 St. Gallen, Switzerland.
Institute of Anatomy, University of Basel, Pestalozzistrasse 20, 4056 Basel, Switzerland.
J Orthop Translat. 2019 Oct 22;24:218-223. doi: 10.1016/j.jot.2019.09.004. eCollection 2020 Sep.
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.
Nineteen knee cadaver specimens with an intact ligament apparatus were fixed in a custom frame, facilitating physiological flexion motion. Virtual total knee arthroplasty (TKA) was performed on three-dimensional models obtained from computed tomography scans (0° and 90° flexions) with systematically altered femur rotations and tibial slopes.
Both the femur rotation and the tibial slope influenced the medial and lateral tibiofemoral flexion gaps ( < 0.001), and the effects differed between the medial and lateral sides ( < 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 < 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 < 0.001).
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.
The article points out the differences in the tibiofemoral gap in total knee endoprostheses due to the systematic internal and external femoral component rotation. While in lower leg extension there are no differences seen, in 90° knee-flexion there are unequal differences within the medial and lateral compartment that show a mathematical relationship towards the femoral compartment rotation which needs to be intraoperatively considered.
量化全膝关节假体中股骨组件的系统性内旋和外旋以及胫骨坡度对胫股内外侧间隙的影响。
19个韧带装置完整的膝关节尸体标本被固定在一个定制框架中，以利于进行生理性屈曲运动。对通过计算机断层扫描获得的三维模型（0°和90°屈曲）进行虚拟全膝关节置换术（TKA），系统性改变股骨旋转和胫骨坡度。
股骨旋转和胫骨坡度均影响胫股内外侧屈曲间隙（P < 0.001），且内外侧的影响存在差异（P < 0.001）。对于7°的股骨组件外旋和内旋，胫股内侧屈曲间隙分别增加2.90±0.34 mm和减小2.66±0.26 mm（均P < 0.001）。对于7°的股骨组件外旋和内旋，胫股外侧屈曲间隙分别减小3.11±0.31 mm和增加3.29±0.33 mm（均P < 0.001）。
对于既定的手术方法，我们建议胫骨坡度为0°时股骨旋转中立，胫骨坡度为9 - 10°时股骨外旋3°。本研究的转化潜力表明，虽然伸直位时股骨组件的旋转对间隙大小无影响，因为旋转轴与间隙垂直，但对于90°屈曲位，我们不仅观察到内外侧间隙大小存在差异，而且两侧差异因内旋或外旋而不等。主要原因是旋转轴的位置并非恰好位于外侧和内侧接触点之间的中点。结果表明，股骨组件的旋转总是会产生不平衡的屈曲间隙。
本文指出了全膝关节假体中由于股骨组件的系统性内旋和外旋导致的胫股间隙差异。虽然在小腿伸直位未见差异，但在膝关节90°屈曲位时，内外侧间室存在不等的差异，且这些差异与股骨间室旋转呈数学关系，这在术中需要加以考虑。
