固定平台后稳定型假体全膝关节置换术后的运动学研究

 目的 探讨固定平台后稳定型假体全膝关节置换(total knee arthroplasty，TKA)术后膝关节在负重屈膝下蹲时的运动学特征。方法 选取10名健康志愿者和10例固定平台后稳定型假体TKA术后患者。制作骨骼及膝关节假体三维模型，在持续X线透视下完成负重下蹲动作，膝关节屈曲度每增加15°截取一幅图像。通过荧光透视分析技术完成三维模型与二维图像的匹配，再现股骨与胫骨在屈膝过程中的空间位置，通过连续的图像分析比较正常与固定平台后稳定型假体TKA术后膝关节在负重下蹲时股骨内、外髁前后移动及胫骨内外旋转幅度。结果 负重下蹲时，正常膝关节平均屈曲136°，股骨内、外髁分别后移(7.3±1.2) mm和(19.3±3.1) mm，胫骨平均内旋23.8°±3.4°；TKA术后膝关节平均屈曲125°，股骨内、外髁分别后移(1.4±1.6) mm和(6.4±1.7) mm，胫骨平均内旋8.5°±3.4°。结论 固定平台后稳定型假体TKA术后膝关节运动与正常膝关节相似，均表现出股骨内、外髁后移及胫骨内旋运动，但幅度小于正常膝关节，且在屈膝过程中存在股骨矛盾性前移及胫骨外旋现象。

In vivo kinematics analysis of the knee joint of people after fixed-bearing posterior stabilized total knee arthroplasty

Objective To compare the kinematics of the knee joint of normal Chinese people and people after fixed-bearing posterior stabilized total knee arthroplasty while doing weight-bearing deep knee-bending using fluoroscopy analysis. Methods From June to December 2010, ten volunteers and ten patients with fixed-bearing posterior stabilized total knee arthroplasty (TKA) were required to perform weight-bearing deep knee-bending activity under surveillance of roentgenization, motion between femur and tibia was analyzed with interval of 15° according to two- to three-dimensional (2D-3D) registration technique. Results During weight-bearing deep knee-bending, the average weight-bearing maximal flexion was 136° in the normal group, which was significantly higher than the 125° in the TKA group. All 10 normal knees present posterior translation of femoral condyle during deep knee-bending, posterior translation of the lateral condyle was greater than medial condyle, thereby creating a medial pivot type of axial rotational pattern in which the tibia internally rotates relative to the femur as flexion increased. The average amount of posterior femoral translation of the medial condyle was 7.3±1.2 mm, whereas the lateral condyle translated posteriorly 19.3±3.1 mm. All knees experienced tibia rotated internally during progressive flexion, and the average amount of axial rotation for the ten subjects from 0° to 135° was 23.8±3.4°. From extension to maximal flexion, the average amount of posterior translation of medial condyle was 1.4±0.6 mm, whereas the lateral condyle translated 6.4±1.7 mm in the posterior direction in the fixed-bearing posterior-stabilized TKA. The average amount of tibial internal rotation was 8.5°±3.4°. Conclusion In normal Chinese people, during knee flexion activities the lateral condyle experiences significantly more amount of posterior translation than the medial condyle, leading to the tibia present medial pivot internal rotation relative to the femur, and the PFC-Sigma fixed-bearing posterior stabilized designs has the similar kinematics with normal knee, but the posterior condylar translation and tibial axial rotation are much less than the normal.