Jack McBain Biomechanical Testing Laboratory Department of Mechanical and Materials Engineering, Western University, 1151 Richmond St, London, ON N6A 5B9, Canada.
J Biomech. 2014 Aug 22;47(11):2672-8. doi: 10.1016/j.jbiomech.2014.05.010. Epub 2014 May 23.
The distal radius fracture (DRF) is a particularly dominant injury of the wrist, commonly resulting from a forward fall on an outstretched hand. In an attempt to reduce the prevalence, costs, and potential long-term pain/deformities associated with this injury, in vivo and in vitro investigations have sought to classify the kinematics and kinetics of DRFs. In vivo forward fall work has identified a preparatory muscle contraction that occurs in the upper extremity prior to peak impact force. The present investigation constitutes the first attempt to systematically determine the effect of static muscle forces on the fracture threshold of the distal radius in vitro. Paired human cadaveric forearm specimens were divided into two groups, one that had no muscle forces applied (i.e., right arms) and the other that had muscle forces applied to ECU, ECRL, FCU and FCR (i.e., left arms), with magnitudes based on peak muscle forces and in vivo lower bound forward fall activation patterns. The specimens were secured in a custom-built pneumatic impact loading device and subjected to incremental impacts at pre-fracture (25 J) and fracture (150 J) levels. Similar fracture forces (6565 (866)N and 8665 (5133)N), impulses (47 (6)Ns and 57 (30)Ns), and energies (152 (38)J and 144 (45)J) were observed for both groups of specimens (p>0.05). Accordingly, it is suggested that, at the magnitudes presently simulated, muscle forces have little effect on the way the distal radius responds to forward fall initiated impact loading.
桡骨远端骨折（DRF）是手腕部特别常见的损伤，通常由手掌伸展的向前跌倒引起。为了降低这种损伤的发生率、成本和潜在的长期疼痛/畸形，体内和体外研究试图对 DRF 的运动学和动力学进行分类。体内向前跌倒研究已经确定了在上肢在达到峰值冲击力之前发生的预备性肌肉收缩。本研究首次尝试系统地确定静态肌肉力对体外桡骨远端骨折阈值的影响。成对的人体尸体前臂标本分为两组，一组不施加肌肉力（即右臂），另一组施加肌肉力到 ECU、ECRL、FCU 和 FCR（即左臂），其大小基于峰值肌肉力和体内下边界向前跌倒激活模式。标本被固定在定制的气动冲击加载装置中，并在预骨折（25 J）和骨折（150 J）水平下进行递增冲击。两组标本的相似骨折力（6565（866）N 和 8665（5133）N）、冲量（47（6）Ns 和 57（30）Ns）和能量（152（38）J 和 144（45）J）（p>0.05）。因此，建议在目前模拟的幅度下，肌肉力对桡骨远端对向前跌倒引发的冲击加载的响应方式影响不大。
