Department of Orthopaedic Surgery, Graduate School of Medical Sciences, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka, 812-8582, Japan.
Department of Orthopaedic Surgery, Faculty of Medical Sciences, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka, 812-8582, Japan; Department of Medical-Engineering Collaboration for Healthy Longevity, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka, 812-8582, Japan.
J Orthop Sci. 2022 May;27(3):665-671. doi: 10.1016/j.jos.2021.02.015. Epub 2021 Apr 28.
Mid-flexion instability is the one of the reasons for patient dissatisfaction after total knee arthroplasty (TKA). The purposes of this study were to evaluate in vivo knee kinematics and clinical outcomes using a novel TKA design with a gradual femoral radius component and s-curve post-cam, which are intended to prevent the instability initiated by sudden reductions in the femoral radius observed with conventional components.
We used radiographic-based, image-matching techniques to analyze femorotibial anteroposterior translation, axial rotation, and anterior/posterior cam-post contact during two dynamic movements, squatting and stair climbing, in 20 knees that had undergone posterior-stabilized fixed-bearing TKA with an improved sagittal profiles of the femoral component and post-cam mechanism. We also evaluated patient-reported outcomes assessed by the 2011 Knee Society Score (KSS 2011).
Squatting and stair climbing produced a similar trend in anteroposterior translation and a relatively small standard deviation at mid-flexion. Although the rotation angles varied widely during squatting and stair climbing, the femoral component was consistently externally rotated. Anterior/posterior cam-post contact during squatting and stair climbing were observed in 0/17 knees and 0/0 knees, respectively. The "Symptoms", "Satisfaction", and "Functional activities" subscales of the KSS 2011 were significantly (P < 0.05) improved postoperatively compared to preoperatively ("Symptoms", 10 to 21; "Satisfaction", 15 to 26; "Functional activities", 25 to 71).
A gradual femoral radius component with an s-curve post-cam provided stable kinematics and favorable clinical results during squatting and stair climbing at 1 year after surgery.
膝关节在完全膝关节置换术后（TKA）发生中度屈曲不稳定是导致患者不满意的原因之一。本研究旨在评估一种新型 TKA 设计的膝关节运动学和临床效果，该设计采用逐渐变细的股骨半径组件和 S 形后凸轮，旨在防止由于常规组件中股骨半径突然减小而引起的不稳定。
我们使用基于射线照相的图像匹配技术来分析 20 例膝关节在深蹲和爬楼梯两种动态运动中股胫前后平移、轴向旋转以及前/后凸轮-销接触情况。这些膝关节均接受了后稳定固定轴承 TKA 治疗，其股骨组件的矢状面曲线得到了改善，后凸轮机构也得到了改进。我们还评估了患者报告的结果，采用 2011 年膝关节协会评分（KSS 2011）进行评估。
深蹲和爬楼梯时的前后平移趋势相似，在中度屈曲时的标准偏差较小。虽然深蹲和爬楼梯时的旋转角度变化很大，但股骨组件始终是外旋的。在深蹲和爬楼梯时，分别有 0/17 例和 0/0 例膝关节观察到前/后凸轮-销接触。与术前相比，术后 KSS 2011 的“症状”、“满意度”和“功能活动”亚量表均有显著改善（P<0.05）（“症状”，10 至 21 分；“满意度”，15 至 26 分；“功能活动”，25 至 71 分）。
术后 1 年，逐渐变细的股骨半径组件和 S 形后凸轮可提供稳定的运动学效果，并在深蹲和爬楼梯时获得良好的临床效果。
