Kamei Keita, Sasaki Eiji, Fujisaki Kazuhiro, Harada Yoshifumi, Yamamoto Yuji, Ishibashi Yasuyuki
Department of Orthopaedic Surgery, Hirosaki University Graduate School of Medicine, Hirosaki, Japan.
Department of Intelligent Machines and System Engineering, Faculty of Science and Technology, Hirosaki University, Hirosaki, Japan.
JSES Int. 2020 Dec 16;5(2):307-313. doi: 10.1016/j.jseint.2020.10.022. eCollection 2021 Mar.
Repetitive mechanical stress on the elbow joint during throwing is a cause of ulnar collateral ligament dysfunction that may increase the compressive force on the humeral capitellum. This study aimed to examine the effects of ulnar collateral ligament material properties on the humeral capitellum under valgus stress using the finite element method.
Computed tomography data of the dominant elbow of five healthy adults were used to create finite element models. The elbows were kept at 90° of flexion with the forearm in the neutral position, and the ulnar collateral ligament was reproduced using truss elements. The proximal humeral shaft was restrained, and valgus torque of 40 N·m was applied to the forearm. The ulnar collateral ligament condition was changed to simulate ulnar collateral ligament dysfunction. Ulnar collateral ligament stiffness values were changed to 72.3 N/mm, 63.3 N/mm, 54.2 N/mm, 45.2 N/mm, and 36.1 N/mm to simulate ulnar collateral ligament laxity. The ulnar collateral ligament toe region width was changed in increments of 0.5 mm from 0.0 to 2.5 mm to simulate ulnar collateral ligament loosening. We assessed the maximum equivalent stress and stress distribution on the humeral capitellum under these conditions.
As ulnar collateral ligament stiffness decreased, the maximum equivalent stress on the humeral capitellum gradually increased under elbow valgus stress ( < .001). Regarding the change in the ulnar collateral ligament toe region width, as the toe region elongated, the maximum equivalent stress of the humeral capitellum increased significantly under elbow valgus stress ( < .001). On the capitellum, the equivalent stress on the most lateral part was significantly higher than that on other parts ( < .01 for all).
Under elbow valgus stress with elbow flexion of 90° and the forearm in the neutral position, ulnar collateral ligament dysfunction increased equivalent stress on the humeral capitellum during the finite element analysis. The highest equivalent stress was noted on the lateral part of the capitellum.
投掷过程中肘关节反复受到的机械应力是尺侧副韧带功能障碍的一个原因，这可能会增加肱骨小头的压力。本研究旨在使用有限元方法研究尺侧副韧带材料特性在 valgus 应力下对肱骨小头的影响。
使用 5 名健康成年人优势肘关节的计算机断层扫描数据创建有限元模型。将肘关节保持在 90°屈曲，前臂处于中立位，使用桁架单元再现尺侧副韧带。限制肱骨干近端，并向前臂施加 40 N·m 的 valgus 扭矩。改变尺侧副韧带状况以模拟尺侧副韧带功能障碍。将尺侧副韧带刚度值分别改为 72.3 N/mm、63.3 N/mm、54.2 N/mm、45.2 N/mm 和 36.1 N/mm 以模拟尺侧副韧带松弛。尺侧副韧带趾区宽度以 0.5 mm 的增量从 0.0 改变至 2.5 mm 以模拟尺侧副韧带松弛。我们评估了在这些条件下肱骨小头上的最大等效应力和应力分布。
随着尺侧副韧带刚度降低，在肘关节 valgus 应力下，肱骨小头上的最大等效应力逐渐增加（P <.001）。关于尺侧副韧带趾区宽度的变化，随着趾区延长，在肘关节 valgus 应力下，肱骨小头的最大等效应力显著增加（P <.001）。在小头上，最外侧部分的等效应力显著高于其他部分（所有 P <.01）。
在肘关节屈曲 90°且前臂处于中立位的肘关节 valgus 应力下，在有限元分析中，尺侧副韧带功能障碍增加了肱骨小头上的等效应力。在小头的外侧部分观察到最高等效应力。
