| Summary: | 博士 === 國立陽明大學 === 醫學工程研究所 === 99 === Abstract
Deficiencies in contemporary posterior crucitate retaining knee included inadequate femoral rollback and insufficient tibial internal rotation during knee flexion. The possible cause was knee prosthetic geometry inconsistent with intact knee. The posterolateral tibial plateau is convex of intact knee whereas most prosthetic designs are concave shape. Again, the meidal condyle is more distal than lateral condyle of intact knee, but most knee prostheses were designed consistent condylar height for matching symmetrical insert articular surface. Therefore, this study attempted to regain normal knee kinematics through a posterior cruciate ligament retaining knee which incorporated convexly lateral tibial plateau and anatomical condylar configuration simultaneously into the prosthesis design. Computational simulation was utilized to analyze motion of three-dimensional knee models, including intact, traditionally symmetrical PCR and new developed PCR knees with convex insert articular surface and with or without different condylar height designs. Solid bones, attachments of ligaments and tendons of simulation models were sourced from magnetic resonance images of the subject. The distal femur was modeled to rotate about the specific axes and the motion of the proximal tibial was unconstrained except for the flexion/extension. Movements of the medial/lateral condyles and tibial rotation were recorded and analyzed. The convex PCR knee was improved the posterior movement of lateral condyle and tibial internal rotation significantly during full range of flexion. Progressively, considered anatomical condylar configuration into prosthetic design could improve femoral rollback and tibial internal rotation during higher knee flexion. It would induce by convexly lateral condyle that eliminated the resistance of shear force by concave shape, and the anatomical condylar configuration could helpful to restore normal knee motion pattern. The clinical results need further investigation to approve the validity and reliability of newly developed anatomic-like posterior ligament retaining knee design.
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