Orthopaedic Surgery Department, Newcastle University Hospital, Newcastle upon Tyne, UK.
Knee Surg Sports Traumatol Arthrosc. 2012 Jul;20(7):1349-56. doi: 10.1007/s00167-011-1824-2. Epub 2011 Dec 21.
Total knee arthroplasty (TKA) is a procedure with function dependent upon correct tensioning of the soft-tissue constraints. The purpose of this study was to examine the length-change behaviour of the collateral ligaments during knee flexion-extension before and after TKA. The influence of differing degrees of internal-external rotation of the femoral component on slackening/tightening of the collateral ligaments during knee flexion was to be studied.
The length-change patterns of the collateral ligaments were measured in eight intact knees in vitro: sutures were passed along the ligaments and attached to displacement transducers. Measurements were repeated after TKA with the femoral component in neutral rotation, then with 5° internal and 5° external rotation.
Both the MCL and LCL slackened during knee flexion from 0° to 110° flexion, at all stages of the experiment. In the native knee, the MCL slackened 2 mm, whilst the LCL slackened 7 mm. The MCL slackened a further 3 mm and the LCL a further 4 mm during flexion post-TKA. A 5° external rotation of the femoral component slackened the MCL 2 mm more and tightened the LCL by 2 mm. The opposite effects resulted from 5° internal rotation.
The collateral ligaments slackened more than normal following TKA, and these length changes were increased by femoral component rotation. External rotation of the femoral component to address patellar tracking may slacken the MCL and thus lead to valgus instability in the flexed knee.
全膝关节置换术（TKA）的功能取决于软组织约束的正确张紧。本研究的目的是检查 TKA 前后膝关节屈伸过程中侧副韧带的长度变化行为。研究了股骨组件不同内外旋转程度对膝关节屈曲时侧副韧带松弛/紧张的影响。
在 8 个完整的离体膝关节中测量侧副韧带的长度变化模式：缝线穿过韧带并连接到位移传感器。在 TKA 后，股骨组件处于中立旋转状态，然后进行 5°内旋和 5°外旋，重复测量。
在整个实验过程中，MCL 和 LCL 在膝关节从 0°到 110°屈曲时都会松弛。在自然膝关节中，MCL 松弛 2mm，而 LCL 松弛 7mm。TKA 后膝关节屈曲时，MCL 进一步松弛 3mm，LCL 进一步松弛 4mm。股骨组件外旋 5°会使 MCL 进一步松弛 2mm，使 LCL 紧张 2mm。股骨组件内旋 5°会产生相反的效果。
TKA 后侧副韧带松弛程度超过正常水平，这些长度变化会因股骨组件旋转而增加。为解决髌骨轨迹问题而使股骨组件外旋可能会使 MCL 松弛，从而导致膝关节屈曲时出现外翻不稳定。
