Medical Devices & Technology Group (MEDITEG), Faculty of Biosciences and Medical Engineering, Universiti Teknologi Malaysia, 81310, Johor Bahru, Johor, Malaysia.
Knee Surg Sports Traumatol Arthrosc. 2014 Dec;22(12):3019-27. doi: 10.1007/s00167-014-3227-7. Epub 2014 Aug 23.
Reproducing the femoral rollback through specially designed mechanism in knee implants is required to achieve full knee function in total knee arthroplasty. Most contemporary implants use cam/post mechanism to replace the function of Posterior Cruciate Ligament. This study was aimed to determine the most appropriate cam and post designs to produce normal femoral rollback of the knee.
Three different cams (triangle, ellipse, and circle) and three different posts (straight, convex, concave) geometries were considered in this study and were analysed using kinematic analyses. Femoral rollback did not occur until reaching 50° of knee flexion. Beyond this angle, two of the nine combinations demonstrate poor knee flexion and were eliminated from the study.
The combination of circle cam with concave post, straight post and convex post showed 15.6, 15.9 and 16.1 mm posterior translation of the femur, respectively. The use of ellipse cam with convex post and straight post demonstrated a 15.3 and 14.9 mm femoral rollback, whilst the combination of triangle cam with convex post and straight post showed 16.1 and 15.8 mm femoral rollback, respectively.
The present study demonstrates that the use of circle cam and convex post created the best femoral rollback effect which in turn produces the highest amount of knee flexion. The findings of the study suggest that if the design is applied for knee implants, superior knee flexion may be possible for future patients.
IV.
在全膝关节置换术中，为了实现膝关节的完全功能，需要通过专门设计的机制使股骨后滚。大多数现代植入物使用凸轮/后柱机制来替代后交叉韧带的功能。本研究旨在确定最适合的凸轮和后柱设计，以实现膝关节正常的股骨后滚。
本研究考虑了三种不同的凸轮（三角形、椭圆形和圆形）和三种不同的后柱（直、凸、凹）几何形状，并通过运动学分析进行了分析。只有在膝关节屈曲达到 50°时，股骨后滚才会发生。超过这个角度，九种组合中的两种表现出膝关节屈曲不良，因此被排除在研究之外。
圆形凸轮与凹形后柱、直后柱和凸后柱的组合分别显示出 15.6、15.9 和 16.1mm 的股骨后移。椭圆形凸轮与凸后柱和直后柱的组合表现出 15.3 和 14.9mm 的股骨后滚，而三角形凸轮与凸后柱和直后柱的组合分别显示出 16.1 和 15.8mm 的股骨后滚。
本研究表明，使用圆形凸轮和凸形后柱可产生最佳的股骨后滚效果，从而产生最大的膝关节屈曲度。研究结果表明，如果将该设计应用于膝关节植入物，未来患者可能会获得更好的膝关节屈曲度。
IV。
