Hefzy M S, Kelly B P, Cooke T D, al-Baddah A M, Harrison L
Department of Biological & Medical Research and Orthopaedic Surgery, King Faisal Specialist Hospital and Research Center, Riyadh, Kingdom of Saudi Arabia.
Biomed Sci Instrum. 1997;33:453-8.
Squatting and kneeling are important daily activities for Middle and Far East cultures that require positioning the knee in deep flexion. In these activities, the limb becomes fully flexed with a knee flexion angle reaching between 150 and 160 degrees and the heel reaching the posterior surface of the upper thigh. Existing knee prostheses do not allow a full return to normal activities for this large population since they are limited to achieving knee flexion of about 120 degrees. Also, there is very limited information on knee kinematics and/or forces in the range beyond 120 degrees. The purpose of this study is to describe the kinematics of normal knees in-vivo, assessed in deep flexion, using bi-planar radiographs. A-P and lateral views were obtained from 5 healthy subjects during three sequential positions of kneeling. In the 1st position, the subject knelt with the knees fully flexed (deep flexion between 150 degrees and 160 degrees) and torso upright. In the 2nd position, the subject bowed forward to an intermediate position (about 120 degrees of knee flexion). In the 3rd position, the subject bowed further until his/her head touched the floor, supporting the upper torso with hands and attaining a knee flexion of about 90 degrees. The results show that past 135 degrees of knee flexion, the patella was found to clear the femoral groove and was in contact only with the condyles. The results also show that the classical femoral "roll back" does not appear to occur in deep flexion. It seems that the lateral femoral condyle rolls over the postero medial aspect of the lateral tibial plateau while contact of the medial femoral condyle occurs more anteriorly, but still in the posterior aspect of the medial tibial plateau. This asymmetric rolling motion implies an element of internal tibial rotation. Furthermore, the tibia was found to articulate with the femur at the most proximal points of the condyles in deep flexion. These data on the kinematics and contact characteristics of the tibio-femoral joint must be considered in any approach to design for a Deep Flexion Knee Implant.
蹲和跪是中东和远东文化中重要的日常活动，这些活动需要将膝盖置于深度屈曲状态。在这些活动中，肢体完全屈曲，膝盖屈曲角度达到150至160度，脚跟触及大腿上部的后表面。现有的膝关节假体无法让大量人群完全恢复正常活动，因为它们只能实现约120度的膝关节屈曲。此外，关于超过120度范围的膝关节运动学和/或力的信息非常有限。本研究的目的是使用双平面X线片描述体内正常膝关节在深度屈曲时的运动学。在5名健康受试者进行连续三个跪姿时，获取了前后位（A-P）和侧位视图。在第一个姿势中，受试者膝盖完全屈曲（深度屈曲在150度至160度之间）且躯干直立地跪着。在第二个姿势中，受试者向前弯腰至中间位置（膝关节屈曲约120度）。在第三个姿势中，受试者进一步弯腰直到头部触地，用手支撑上半身，膝关节屈曲约90度。结果表明，在超过135度的膝关节屈曲时，发现髌骨脱离股骨沟，仅与髁接触。结果还表明，经典的股骨“后滚”在深度屈曲时似乎并未发生。似乎外侧股骨髁在外侧胫骨平台的后内侧方面滚动，而内侧股骨髁的接触更靠前，但仍在内侧胫骨平台的后侧。这种不对称滚动运动意味着胫骨有内旋成分。此外，发现在深度屈曲时胫骨在髁的最近端点与股骨形成关节。在设计深度屈曲膝关节植入物的任何方法中，都必须考虑这些关于胫股关节运动学和接触特征的数据。
