Department of Orthopaedic Surgery, Graduate School of Medicine, Kyoto University, Kyoto, Japan.
Bone Joint J. 2020 Jun;102-B(6_Supple_A):36-42. doi: 10.1302/0301-620X.102B6.BJJ-2019-1531.R1.
This study aimed to evaluate the association between the sagittal alignment of the femoral component in total knee arthroplasty (TKA) and new Knee Society Score (2011KSS), under the hypothesis that outliers such as the excessive extended or flexed femoral component were related to worse clinical outcomes.
A group of 156 knees (134 F:22 M) in 133 patients with a mean age 75.8 years (SD 6.4) who underwent TKA with the cruciate-substituting Bi-Surface Knee prosthesis were retrospectively enrolled. On lateral radiographs, γ angle (the angle between the distal femoral axis and the line perpendicular to the distal rear surface of the femoral component) was measured, and the patients were divided into four groups according to the γ angle. The 2011KSSs among groups were compared using the Kruskal-Wallis test. A secondary regression analysis was used to investigate the association between the 2011KSS and γ angle.
According to the mean and SD of γ angle (γ, 4.0 SD 3.0°), four groups (Extended or minor flexed group, -0.5° ≤ < 2.5° (n = 54)), Mild flexed group (2.5° ≤ < 5.5° (n = 63)), Moderate flexed group (5.5° ≤ < 8.5° (n = 26)), and Excessive flexed group (8.5° ≤ γ (n = 13)) were defined. The Excessive flexed group showed worse 2011KSSs in all subdomains (Symptoms, Satisfaction, Expectations, and Functional activities) than the Mild flexed group. Secondary regression showed a convex upward function, and the scores were highest at = 3.0°, 4.0°, and 3.0° in Satisfaction, Expectations, and Functional activities, respectively.
The groups with a sagittal alignment of the femoral component > 8.5° showed inferior clinical outcomes in 2011KSSs. Secondary regression analyses showed that mild flexion of the femoral component was associated with the highest score. When implanting the Bi-Surface Knee prosthesis surgeons should pay careful attention to avoiding flexing the femoral component extensively during TKA. Our findings may be applicable to other implant designs. Cite this article: 2020;102-B(6 Supple A):36-42.
本研究旨在评估全膝关节置换术（TKA）中股骨组件矢状面对线与新膝关节学会评分（2011KSS）之间的关系，假设过度伸展或过度弯曲的股骨组件等异常情况与较差的临床结果相关。
回顾性纳入了 133 例患者（134 例女性，22 例男性）的 156 膝（平均年龄 75.8 岁，标准差 6.4 岁），这些患者均接受了带有交叉韧带替代双表面膝关节假体的 TKA。在侧位 X 线片上，测量 γ 角（股骨远端轴与垂直于股骨组件远端后表面的线之间的角度），根据 γ 角将患者分为四组。使用 Kruskal-Wallis 检验比较各组 2011KSS。使用二次回归分析调查 2011KSS 与 γ 角之间的关系。
根据 γ 角的平均值和标准差（γ，4.0 SD 3.0°），将四组定义为：过度伸展或轻微弯曲组（-0.5°≤γ<2.5°（n=54））、轻度弯曲组（2.5°≤γ<5.5°（n=63））、中度弯曲组（5.5°≤γ<8.5°（n=26））和过度弯曲组（8.5°≤γ（n=13））。与轻度弯曲组相比，过度弯曲组在所有亚领域（症状、满意度、期望和功能活动）的 2011KSS 都较差。二次回归显示为凸向上的函数，在满意度、期望和功能活动中，得分分别在γ=3.0°、4.0°和 3.0°时最高。
股骨组件矢状面对线>8.5°的组在 2011KSS 中表现出较差的临床结果。二次回归分析显示，股骨组件轻度弯曲与得分最高相关。在植入双表面膝关节假体时，外科医生应注意在 TKA 中避免股骨组件过度弯曲。我们的发现可能适用于其他植入物设计。引用本文：2020；102-B（6 增刊 A）：36-42。
