Center for Musculoskeletal Research, Mechanical, Aerospace, and Biomedical Engineering, University of Tennessee, Knoxville, Tennessee.
J Arthroplasty. 2021 Jul;36(7):2379-2385. doi: 10.1016/j.arth.2020.12.007. Epub 2020 Dec 11.
It has been hypothesized that increasing posterior tibial slope can influence condylar rollback and play a role in increasing knee flexion. However, the effects of tibial slope on knee kinematics are not well studied. The objective of this study is to assess the effects of tibial slope on femorotibial kinematics and kinetics for a posterior cruciate retaining total knee arthroplasty design.
A validated forward solution model of the knee was implemented to predict the femorotibial biomechanics of a posterior cruciate retaining total knee arthroplasty with varied posterior slopes of 0°-8° at 2° intervals. All analyses were conducted on a weight-bearing deep knee bend activity.
Increasing the tibial slope shifted the femoral component posteriorly at full extension but decreased the overall femoral rollback throughout flexion. With no tibial slope, the lateral condyle contacted the polyethylene 6 mm posterior of the midline, but as the slope increased to 8°, the femur shifted an extra 5 mm, to 11 mm posterior of the tibial midline. Similar shifts were observed for the medial condyle, ranging from 7 mm posterior to 13 mm posterior, respectively. Increasing posterior slope decreased the posterior cruciate ligament tension and femorotibial contact force.
The results of this study revealed that, although increasing the tibial slope shifted the femur posteriorly at full extension and maximum flexion, it reduced the amount of femoral rollback. Despite the lack of rollback, a more posterior location of condyles suggests lower chances of bearing impingement of the posterior femur and may explain why increasing slope may lead to higher knee flexion.
有人假设增加胫骨后倾角可以影响髁间后滚，并在增加膝关节屈曲方面发挥作用。然而，胫骨后倾角对膝关节运动学的影响尚未得到很好的研究。本研究旨在评估胫骨后倾角对后稳定型全膝关节置换设计的股骨胫骨运动学和动力学的影响。
采用已验证的膝关节正向解模型，预测 0°-8°间隔的 2°后倾角变化对后稳定型全膝关节置换的股骨胫骨生物力学的影响。所有分析均在负重深膝弯曲活动中进行。
增加胫骨后倾角会使股骨组件在完全伸展时向后移位，但会减少整个膝关节屈曲过程中的整体股骨后滚。在没有胫骨后倾角的情况下，外侧髁在中线后 6mm 处接触聚乙烯，而随着斜率增加到 8°，股骨向后移动 5mm，达到胫骨中线后 11mm。内侧髁也观察到类似的移位，分别为 7mm 到 13mm 后。增加后倾角会降低后交叉韧带张力和股骨胫骨接触力。
本研究结果表明，尽管增加胫骨后倾角会使股骨在完全伸展和最大屈曲时向后移位，但会减少股骨后滚的程度。尽管没有后滚，但髁间的后移位置较低，表明股骨后撞击的可能性较低，这可能解释了为什么增加斜率可能导致更高的膝关节屈曲。
