人工全膝关节置换术中胫股关节旋转对线不良的影像学分析

目的分析和探究造成全膝置换术中胫股关节旋转对线不良的可能原因,指导术中选择正确的确定假体部件旋转的方法,以减少术后并发症。方法选择40例正常人的膝关节作为研究对象,男、女各20例,年龄18～42岁。应用螺旋CT扫描(层厚0.5mm)获取膝关节的横断面图像,采用Autocad2004软件测量股骨假体的旋转轴与胫骨假体的旋转轴之间的关系,运用统计学方法分析临床上选择临床上髁轴、外科上髁轴、股骨后髁轴等方法可能存在的潜在的胫股旋转对线不良及其影响程度。结果术中胫骨假体旋转以胫骨结节内、中1/3交界处来确定,而股骨假体旋转分别以临床上髁轴、外科上髁轴、股骨后髁轴外旋3°来确定,可能产生的胫股旋转对线不良的交角平均值分别为2.94°、6.50°、6.83°。结论全膝置换术中利用骨性解剖标志各自独立地确定胫骨假体、股骨假体的旋转对线必然会产生胫股旋转对线不良,而临床上髁轴产生的影响较小。

Radiographic analysis of rotational malalignment between tibial component and femoral component in total knee arthroplasty

OBJECTIVE: To identify possible reasons of rotational mismatch between tibial component and femoral component in total knee arthroplasty and choose a right reference axis for placing the components in the operation and to decrease the complications. METHODS: Forty normal Chinese knees were studied. There were 20 men and 20 women, and average age was 34 years (range, 18 - 42 years). The images of cross sections of the distal femur were obtained by spiral CT scanning (0.5 mm thickness). Scan direction was aligned to be in the plane perpendicular to the mechanical axis of the tibia. On the images of the distal femur and the proximal tibia, three baselines for the anteroposterior axis of the femoral component were drawn based on the clinical epicondylar axis and the surgical epicondylar axis and 3 degrees lateral rotated to the posterior condylar surfaces of the femur separately, and a baseline for the anteroposterior axis of the tibial component was drawn based on the medial 1/3 of the tibial tuberosity. The rotational mismatch angles were measured between each component by using the Autocad software. RESULTS: The mean rotational mismatch angle between tibial component and femoral component is 2.94 degrees for the clinical epicondylar axis, 6.50 degrees for the surgical epicondylar axis and 6.83 degrees for 3 degrees lateral rotation of the femoral component referenced to the posterior condylar axis separately. CONCLUSIONS: Landmarks of each bone were the intrinsic cause of the rotational mismatch in total knee arthroplasty. The clinical epicondylar axis can be chosen for the ideal reference to rotational alignment of the femoral component because of its minimal rotational mismatch between each component.