新型外卡式人工全腕关节假体的设计与活动范围研究

Design and kinematic research of new external-fixed total wrist prosthesis

目的通过测量及收集桡骨远端关节面解剖学数据,设计新型外卡式全腕关节假体;初步评价新型外卡式全腕关节置换后腕关节活动功能。方法根据在50例成人腕关节正侧位片(由解放军昆明总医院影像科提供)测得桡骨远端关节面掌倾角与尺偏角,结合已有文献数据及国外人工全腕关节设计经验,设计新型外卡式人工全腕关节系统,掌倾角和尺偏角分别设计为10°和7°。活动范围测量实验采用自身配对设计,以6具新鲜冰冻保存成人上肢标本,使用聚甲基丙烯酸甲酯根据实验操作台固定器形状进行包埋处理。将标本固定于三维运动实验台上,分别于腕关节近端、远端各固定4个红外线可识别的球形标记物,向上肢标本掌屈、背伸、尺偏、桡偏4个方向施加4 Nm的纯力矩,使腕关节相应做上述运动。记录0载荷和最大载荷时腕关节运动状态的图像并通过Cotex 3.0运动捕捉系统软件记录并计算出腕关节在4个方向上的活动范围。术前测量完成后,对6例标本使用新型外卡式人工全腕关节进行全腕关节置换,重复上述实验步骤,测量新型人工腕关节假体置换后腕关节活动度。比较6具标本置换前与置换后在掌屈、背伸、尺偏、桡偏4个方向上的活动度。应用配对t检验对前后数据做统计学分析。结果所有标本在行全腕关节置换手术过程中术程顺利,术后关节活动流畅。相同载荷下,术后腕关节在背伸、尺偏、桡偏方向的活动度较术前无统计学差异(P>0.05),术前掌屈方向最大活动度为(72.3±4.8)°,术后掌屈方向最大活动度为(54.9±6.1)°,二者差异有统计学意义(t=8.34,P<0.01)。结论新型外卡式全腕关节的设计在活动范围方面基本满足了腕关节的生物力学要求,值得进一步探究其性能。

Objective To design a new type of external-fixed wrist prosthesis and to evaluate the function of it.Methods According to the radial and ulnar inclinations of distal radius articular surface measured in 50 cases of adult wrist radiographs,and combining the data from literatures and abroad artificial wrist joint design experience,a new type of external-fixed artificial wrist joint system was designed,of which the radial and ulnar inclinations were designed as 10°and 7°.Six wrists from fresh frozen adult cadavers were fixed in 3D motion experiment table.Markers which can be identified by the infrared camera were set in the wrist joint;4 Nm was loaded to the upper limb at four directions including flexion,extension,ulnar deviation and radial deviation.The corresponding images were captured when the zero load and maximum load applied to the wrist joint by Cotex 3.0 software,and the ranges of motion of wrist joint in four directions were calculated.Total wrist arthroplasty using new type of external-fixed wrist prosthesis was performed in the six specimens,and the experimental procedures were repeated to measure the range of motions of the wrist joint prostheses.Paired t test was applied to compare the pre-and postoperative data.Results Total wrist arthroplasty was successfully performed on all the samples,and the postoperative joint activities were good.Under the same load,the postoperative ranges of motion of the wrist in dorsal flexion,ulnar deviation,and radial deviation showed no statistical difference comparing with the preoperative ones(P>0.05).The preoperative flexion was(72.3±4.8)°,the postoperative maximum activity of flexion was(54.9±6.1)°,there were significant differences between the two(t=8.34,P<0.01).Conclusion The new design of external-fixed wrist prosthesis can meet the basic requirements of wrist biomechanics,which is worthy of further research.