Hatta Taku, Shinagawa Kiyotsugu, Kawakami Jun, Yamamoto Nobuyuki, Kitada Masaaki, Itoi Eiji
Department of Orthopaedic Surgery, Tohoku University School of Medicine, Sendai, Japan.
Department of Orthopaedic Surgery, Tohoku University School of Medicine, Sendai, Japan.
Clin Biomech (Bristol). 2020 Dec;80:105140. doi: 10.1016/j.clinbiomech.2020.105140. Epub 2020 Jul 30.
It remains unclear how the head and stem diameters for the radial head prosthesis could affect mechanical properties of the lateral collateral ligament measured by strain changes during elbow and forearm motions.
Eight cadaveric specimens were secured to the device, which allows elbow flexion-extension and forearm pro-supination. Using six different implant combinations comprising 2 sizes for the head (long- and short-axis of the native head) and 3 sizes for the stem (press-fit, -1 mm, and -2 mm downsizing), prostheses were attached via the posterior approach. A differential variable reluctance transducer placed on the central portion of the radial collateral ligament were used for strain measurement with elbow flexion at 0°, 30°, 60°, and 90°. At each position, the strain patterns with the forearm in the neutral and 45° pro-supination positions were also assessed.
Specimens implanted with long-axis head component showed greater increases in the ligament strain during elbow flexion than intact specimens or those implanted with short-axis head. Compared to press-fit stem, implants with downsizing to -1 mm approximated strain patterns during pro-supination with elbow extension to intact condition.
Morphologic variation of the head and stem components in radial head prostheses led to altered strain patterns in the lateral collateral ligament during elbow and forearm motions. A short-axis head component can be used to prevent excessive strain changes after the prosthesis application. Downsizing of the stem component might be an option for approximating the biomechanics at the radiocapitellar joint during forearm rotation to the intact elbow.
目前尚不清楚桡骨头假体的头部和柄部直径如何通过肘部和前臂运动期间的应变变化来影响外侧副韧带的力学性能。
将八个尸体标本固定在可实现肘部屈伸和前臂旋前-旋后的装置上。使用六种不同的植入物组合，包括两种尺寸的头部（与天然头部的长轴和短轴相对应）和三种尺寸的柄部（压配、缩小1毫米和缩小2毫米），通过后路植入假体。将差动可变磁阻传感器放置在桡侧副韧带的中央部分，用于在肘部屈曲0°、30°、60°和90°时测量应变。在每个位置，还评估了前臂处于中立位和45°旋前-旋后位时的应变模式。
植入长轴头部组件的标本在肘部屈曲时韧带应变的增加幅度大于完整标本或植入短轴头部的标本。与压配柄相比，缩小至-1毫米的植入物在旋前并伴有肘部伸展时的应变模式接近完整状态。
桡骨头假体头部和柄部组件的形态变化导致肘部和前臂运动期间外侧副韧带的应变模式改变。短轴头部组件可用于防止假体植入后出现过度的应变变化。缩小柄部组件的尺寸可能是一种在进行前臂旋转时使桡骨头关节的生物力学接近完整肘部的选择。
