A COMPUTER AIDED MEASURING SYSTEM FOR CONTACT PRESSURE DISTRIBUTION IN ARTIFICIAL KNEE JOINT

人工膝关节置换术通常适用于严重损伤的膝关节。虽然目前已有多种类型的人工膝关节被开发并应用于临床治疗，但仍需再次手术。为解决人工股胫骨假体松动等并发症，研制了一套微型计算机辅助测量系统，可测量人工股胫骨关节在手术过程中的接触压力分布，以防止膝关节偏心负荷。该系统由12个压力传感器埋置在胫骨假体试验中的测量装置和用于分析压力并直观显示压力分布变化的微型计算机组成。还设计并开发了一台带另一个微型计算机系统的膝部执行器，以给出。对膝关节在行走、从椅子上站立、上下楼梯等过程中膝关节的定量运动(关节角度)和载荷(足力)进行了不同的模式，结合接触压力测量系统和膝关节致动器，对身体膝关节进行了实验研究。结果表明，传统的利用X线平片评价人工膝关节置换术成败的方法具有一定的局限性，本文提出的人工膝关节置换术中假体定位的动态三维评价方法是非常重要的。

The replacement surgery of artificial knee joint is usually indicated for the severely damaged knee. Although many kinds of artificial knee joints have been developed and utilized in clinical treatment, a reoperation is needed . in some cases to treat such complications as loosening of prosthesis due mainly to technical failure.A microcomputer aided measuring system was newly developed, which allows the measurement of contact pressure distribution in artificial femoro-tibial joint during operation in order to prevent the eccentric load in the knee. The system was composed of a measuring apparatus where twelve pressure sensors are buried in the trial of tibial component and a microcomputer for analyzing pressure and displaying visually the changes in pressure distribution. A knee actuator with another microcomputer system was also designed and developed so as to give. continuously various patterns of both quantitative knee-motion(joint angle) and loading(foot force) to the knee joint as walking, standing up from a chair, stepping up and down the stairs, and so on.By combining the contact pressure measuring system and the knee actuator, the experimental investigations were made using cadaveric knee joints. The results strongly suggested that the conventional method for evaluating success or failure of the replacement of artificial knee using plain roentogenogram has a certain limitation and the dynamic three dimensional evaluation for the positioning of the prostheses presented herein is quite important.Conclusively, the microcomputer aided measuring system appears to be useful and helpful for evaluating the positioning of the prosthesis during replacement surgery.