Wilps Tyler John, Chan Calvin K, Yamakawa Satoshi, Takaba Keishi, Takeuchi Satoshi, Kaufmann Robert A, Debski Richard E
Department Orthopaedic Surgery, University of Pittsburgh, Pittsburgh, PA; Department of Bioengineering and Orthopaedic Robotics Laboratory, University of Pittsburgh, Pittsburgh, PA.
Department Orthopaedic Surgery, University of Pittsburgh, Pittsburgh, PA.
J Hand Surg Am. 2025 Mar;50(3):373.e1-373.e6. doi: 10.1016/j.jhsa.2023.07.010. Epub 2023 Aug 17.
This study aimed to examine the effect of flexion on valgus carrying angle in the human elbow using a dynamic elbow testing apparatus.
Active elbow motion was simulated in seven cadaveric upper extremities. Six electromechanical actuators simulated muscle action, while 6 degrees-of-freedom joint motion was measured with an optical tracking system to quantify the kinematics of the ulna with respect to the humerus as the elbow was flexed at the side position. Repeatability of the testing apparatus was assessed in a single elbow over five flexion-extension cycles. The varus angle change of each elbow was compared at different flexion angles with the arm at 0° of humerothoracic abduction or dependent arm position.
The testing apparatus achieved excellent kinematic repeatability (intraclass correlation coefficient, >0.95) throughout flexion and extension. All elbows decreased their valgus carrying angle during flexion from 0° to 90° when the arm was maintained at 0° of humerothoracic abduction. Elbows underwent significant total varus angle change from full extension of 3.9° ± 3.4° (P = .007), 7.3° ± 5.2° (P = .01), and 8.9° ± 7.1° (P = .02) at 60°, 90°, and 120° of flexion, respectively. No significant varus angle change was observed between 0° and 30° of flexion (P = .66), 60° and 120° of flexion (P = .06), and 90° and 120° of flexion (P = .19).
The dynamic elbow testing apparatus characterized a decrease of valgus carrying angle during elbow flexion and found that most varus angle changes occurred between 30° and 90° of flexion. All specimens underwent varus angle change until at least 90° of flexion.
Our model establishes the anatomic decrease in valgus angle by flexion angle in vitro and can serve as a baseline for testing motion profiles of arthroplasty designs and ligamentous reconstruction in the dependent arm position. Future investigations should focus on characterizing motion profile change as the arm is abducted away from the body.
本研究旨在使用动态肘部测试装置，研究屈曲对人肘部外翻携带角的影响。
在7具尸体上肢上模拟主动肘部运动。6个电动致动器模拟肌肉动作，同时用光学跟踪系统测量6自由度关节运动，以量化在侧位屈曲肘部时尺骨相对于肱骨的运动学。在一个肘部进行5个屈伸周期，评估测试装置的重复性。将每个肘部在不同屈曲角度下的内翻角变化与肱骨胸外展0°或手臂下垂位置时进行比较。
测试装置在整个屈伸过程中实现了出色的运动学重复性（组内相关系数>0.95）。当手臂保持在肱骨胸外展0°时，所有肘部在从0°到90°的屈曲过程中外翻携带角均减小。肘部在屈曲60°、90°和120°时，分别从完全伸展时的3.9°±3.4°（P = 0.007）、7.3°±5.2°（P = 0.01）和8.9°±7.1°（P = 0.02）发生显著的总内翻角变化。在屈曲0°至30°（P = 0.66）、60°至120°（P = 0.06）和90°至120°（P = 0.19）之间未观察到显著的内翻角变化。
动态肘部测试装置显示肘部屈曲期间外翻携带角减小，并发现大多数内翻角变化发生在屈曲30°至90°之间。所有标本在至少屈曲90°之前均发生内翻角变化。
我们的模型确定了体外屈曲角度导致的外翻角解剖学减小，可作为测试手臂下垂位置的关节置换设计和韧带重建运动曲线的基线。未来的研究应专注于描述手臂从身体外展时运动曲线的变化。
