BACKGROUND Component malalignment in unicompartmental knee arthroplasty (UKA) has been related to the concentration in tibiofemoral joint of contact stress and to poor post-operative outcomes. Few studies investigated a biomechanical effect of femur component position in sagittal plane. The purpose of this study was to evaluate the biomechanical effect of the femoral components on the sagittal alignment under flexion and extension conditions using computational simulations. METHODS The flexion and extension conditions of the femoral component were analyzed from 10° extension to 10° flexion in 1° increments. We considered the contact stresses in the polyethylene (PE) inserts and articular cartilage, and the force on the collateral ligament, under gait cycle conditions. RESULTS The contact stress on the PE insert increased as flexion of the femoral component increased, but there was not a remarkable difference in the amount of increased contact stress upon extension. There was no difference in the contact stress on the articular cartilage upon extension of the femoral component, but it increased in flexion during stance and double support periods. The forces on the medial collateral ligaments increased with the extension and decreased with the flexion of the femoral component, whereas the forces on the lateral collateral ligaments showed opposite trends. CONCLUSIONS Surgeons should be concerned with femoral component position on UKA not only in frontal plane but also in the sagittal plane, because flexion or extension of the femoral component may impact the PE or opposite compartment along with the surrounding ligaments around knee joint.

中文翻译：

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关于单室膝关节置换术中股骨组件矢状位的生物力学效应。

背景技术单室膝关节置换术（UKA）中的组件错位与接触应力在胫股关节中的浓度以及术后不良预后有关。很少有研究调查矢状面中股骨组件位置的生物力学效应。这项研究的目的是使用计算模拟来评估股骨组件在弯曲和伸展条件下对矢状面对准的生物力学作用。方法分析了股骨组件的屈曲和伸展情况，从10°伸展到10°屈曲，增量为1°。我们考虑了步态周期条件下聚乙烯（PE）插入物和关节软骨的接触应力以及对侧副韧带的作用力。结果PE插入物上的接触应力随着股骨组件屈曲的增加而增加，但延伸时接触应力的增加量没有显着差异。股骨组件伸展时，关节软骨上的接触应力没有差异，但在站立和双支撑期间其屈曲增加。内侧副韧带上的力随着股骨组件的伸展而增加而减小，而随着股骨组件的弯曲而减小，而外侧副韧带上的力却呈现相反的趋势。结论外科医生应关注UKA上的股骨部位位置，不仅在额面，而且在矢状面，