全膝关节置换术后股胫关节运动学轨迹的数字化模型研究

A kinematic study of the tibiofemoral joint after total knee arthroplasty using in vivo fluoroscopyand digital model

目的通过透视技术结合数字化模型注册技术分析全膝关节置换术后股骨假体与胫骨垫片之间的相对运动和接触位置。方法2007年7月至2008年6月，接受GENESISⅡ假体全膝关节置换术患者16例，均为女性；年龄56～76岁，平均66．4岁。随访48-60个月，平均（56±3）个月。采用膝关节学会评分（KneeSocietyScore，KSS）评价膝关节功能；采用循环透视方法获取影像学数据，对假体逆向数字建模，进行数字模型和影像学数据的匹配，重建膝关节的三维运动；测量股骨内、外髁接触位置的移动，计算胫骨内旋角度，测量股骨凸轮和胫骨立柱的接触时相和范围。结果末次随访时KSS膝评分（93±5）分，功能评分（88±13）分，与术前比较差异有统计学意义。股骨内髁的移动范围（8．5±2．5）mm，外髁的移动范围（9．5±4．8）mm，胫骨内旋角度2．5°±8．4°。屈膝约30°-40°时凸轮和立柱发生接触，立柱后方的接触范围（8．0±1．8）mm。胫骨平台后倾角度越大，凸轮和立柱的接触越晚。结论全膝关节置换术后股胫关节的运动学特征与正常膝关节不同，膝关节屈曲10°-30°时股骨内髁前移，屈曲大于40°后股骨内、外髁后移，胫骨平台后倾与凸轮和立柱的接触时相有相关性。

Objective To investigate the relative motion between the femoral component and the tibial insert through the technology of fluoroscopy and digital model. Methods Sixteen female patients （16 knees） with knee osteoarthritis were performed TKA （GENESIS Ⅱ） from July 2007 to June 2008. The mean age was 66.4 years （range from 56 to 76 years）. All patients were followed up 48 months to 60 months, with the mean of 56＋3 months. The postoperative clinical function was evaluated by Knee Society Score （KSS）. To match the digital model to the imaging data of fluoroscopy using 2D-3D automatic registration technology and reconstruct motion of the knee after TKA. The movement of contact position between femoral medial and lat- eral condyle and tibial insert and tibial internal rotation during flexion were measured. The contact time and range between femoral cam and tibial post were analyzed. Results The cases were statistically improved in KSS postoperatively, knee score was 93±5 and function score 88±13. The range of movement for femoral me- dial condyle was 8.5±2.5 mm, and the lateral condyle was 9.5±4.8 mm, the range of tibial internal rotation was 2.5°±8.4°. The contact of cam and post was observed after 30°-40°flexion of the knee, and the range was 8.0±1.8 mm. The greater tilting angle of the tibial plateau was, the later contact between cam and post happened. Conclusion The kinematics of tibiofemoral joint after TKA is different from the kinematics of normal knee. With knee flexion within 10°-30°, femoral medial condyle moves forward. When flexion is greater than 40°, medial and lateral condyle begins rollback. The time of contact of cam and post is relative to tibial prosthesis slope.