Department of Orthopedic Surgery, College of Medicine, Chung-Ang University, Seoul, Korea.
Knee Surg Sports Traumatol Arthrosc. 2013 May;21(5):1029-35. doi: 10.1007/s00167-012-2111-6. Epub 2012 Jul 5.
It is reported that the length of the posterior cruciate ligament (PCL) fibres increases as the knee flexes, and the magnitude of the length change reaches up to 9.8 mm throughout the range of motion, which exceeds the range of failure strain. Therefore, we postulated that a compensatory mechanism must be recruited to overcome this large strain in order to maintain physiologic function as a key component of joint kinematics. Our main objective was to compare the length change pattern for the linear distance between the femoral and tibial tunnels with the length change patterns derived from a real isometer test of different curvatures.
We utilized ten intact cadaveric knees and created a vertical femoral tunnel (5 mm medial to the roof of the intercondylar notch and 5 mm proximal from the articular margin) and lateral tibial tunnels (5 mm proximal to the posterior bony ridge on the lateral side of the PCL fibre) and performed a 3D-CT scan at 0º, 30º, 60º, 90º, and 120º. The distances between the femoral and tibial tunnels were calculated from the 3D coordinates. Real isometry was checked both (1) over the PCL and (2) under the PCL using an isometer with an accuracy of 0.1 mm.
The path over the PCL had the longest intra-articular length, followed by the path under the PCL, and the lengths measured by CT, respectively. The path over the PCL had a more curved path compared with the path under the PCL and the lengths measured by CT. The lengths measured by CT showed significantly larger excursion than the real isometer test. The path over the PCL showed the least excursion through the range of motion, followed by the path under the PCL, and the lengths measured by CT, respectively.
Our findings suggested that a more curved PCL path has better isometry because the curvature of the PCL compensates for the length change between 0º and 60º flexion. In remnant preservation PCL reconstruction, the passage of graft over the PCL would have increased intra-articular length and better isometry compared with straight under the PCL path.
Basic science study.
据报道，后交叉韧带（PCL）纤维的长度会随着膝关节的弯曲而增加，在整个运动范围内，长度变化幅度可达 9.8mm，超过了失效应变的范围。因此，我们推测为了克服这种大应变，必须募集一种代偿机制，以维持作为关节运动学关键组成部分的生理功能。我们的主要目的是比较股骨和胫骨隧道之间直线距离的长度变化模式与不同曲率的实际等距测试得出的长度变化模式。
我们使用了 10 个完整的尸体膝关节，建立了一个垂直的股骨隧道（距髁间窝顶 5mm，距关节缘 5mm 近端）和外侧胫骨隧道（距 PCL 纤维外侧后侧骨嵴 5mm 近端），并在 0°、30°、60°、90°和 120°进行了 3D-CT 扫描。从 3D 坐标计算股骨和胫骨隧道之间的距离。使用精度为 0.1mm 的等距仪分别对 PCL 上和 PCL 下进行了实际等距检查。
PCL 上的路径具有最长的关节内长度，其次是 PCL 下的路径，然后是 CT 测量的长度。PCL 上的路径比 PCL 下的路径和 CT 测量的长度具有更弯曲的路径。CT 测量的长度显示出比实际等距测试更大的位移。PCL 上的路径在整个运动范围内的位移最小，其次是 PCL 下的路径，然后是 CT 测量的长度。
我们的研究结果表明，更弯曲的 PCL 路径具有更好的等距性，因为 PCL 的曲率补偿了 0°至 60°屈曲之间的长度变化。在残余保留 PCL 重建中，与直下 PCL 路径相比，移植物通过 PCL 上方的通道将增加关节内长度和更好的等距性。
基础科学研究。
