Eckhoff Donald, Hogan Craig, DiMatteo Laura, Robinson Mitch, Bach Joel
Department of Orthopaedics, University of Colorado Health Sciences Center, Aurora, CO 80045-0510, USA.
Clin Orthop Relat Res. 2007 Aug;461:238-44. doi: 10.1097/BLO.0b013e318112416b.
Locating the true flexion-extension axis of the knee can play an important role in component placement in a total knee arthroplasty, especially using contemporary computer-assisted surgical navigation. We determined if the commonly used transepicondylar axis is an accurate and reproducible substitute for the flexion-extension axis. Twenty-three fresh-frozen cadaveric distal femurs with intact soft tissue were imaged with computed tomography and reconstructed in three-dimensional virtual space. The transepicondylar axis was compared with a line equidistant from the articular surface of each femoral condyle. Measures were performed by three observers three times for each specimen. Interobserver and intraobserver variations were small, but the differences between axes were approximately 5 degrees. The difference between axes decreased when projected from three-dimensional space to traditional two-dimensional planes (coronal and transverse), explaining why this discrepancy has not been previously documented. The greater difference in three-dimensional space may account for midrange instability reported in total knee arthroplasty. The increased accuracy afforded by computer-assisted surgical navigation in total knee arthroplasty may be lost and increased malposition of components may occur if this discrepancy between reference axes is not appreciated and addressed.
确定膝关节真正的屈伸轴在全膝关节置换术中的假体放置方面可发挥重要作用，尤其是在使用当代计算机辅助手术导航时。我们确定常用的经髁轴是否是屈伸轴的准确且可重复的替代物。对23个带有完整软组织的新鲜冷冻尸体股骨远端进行计算机断层扫描成像，并在三维虚拟空间中重建。将经髁轴与距每个股骨髁关节面等距的一条线进行比较。三位观察者对每个标本进行三次测量。观察者间和观察者内的差异较小，但两轴之间的差异约为5度。当从三维空间投影到传统二维平面（冠状面和横断面）时，两轴之间的差异减小，这解释了为何此前未记录到这种差异。三维空间中更大的差异可能是全膝关节置换术中报告的中期不稳定的原因。如果未认识到并解决参考轴之间的这种差异，全膝关节置换术中计算机辅助手术导航所提供的更高准确性可能会丧失，并且假体位置不当的情况可能会增加。
