Off-axis loads cause failure of the distal radius at lower magnitudes than axial loads: a finite element analysis.
Off-axis loads cause failure of the distal radius at lower magnitudes than axial loads: a finite element analysis.
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DOI：
10.1016/j.jbiomech.2007.01.018
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发表时间：
2007
影响因子：
2.4
通讯作者：
K. Troy;M. Grabiner
中科院分区：
文献类型：
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作者：
K. Troy;M. Grabiner
桡骨远端（Colles）骨折是老年人常见的跌倒相关损伤，经常导致长期疼痛和日常生活活动能力降低。由于跌倒过程中骨折的发生取决于骨的强度和撞击本身的运动学和动力学，我们试图了解骨矿物质密度（BMD）和载荷方向的变化如何影响桡骨远端的骨折强度和骨折起始位置。使用桡骨、舟状骨和月骨的三维有限元模型检查±2%和±4% BMD的变化，以及桡骨上的轴向和生理相关离轴载荷。BMD的变化导致骨折强度的相似百分比变化。然而，修改施加的载荷以包括背侧和外侧组件（假设腕关节的背侧视图，而不是解剖视图）导致断裂强度降低47%（轴向失效载荷：2752 N，离轴：1448 N）。加载方向也影响断裂起始位置。轴向加载桡骨在茎突近端的内侧表面上失效。相反，离轴载荷，包含背侧和外侧组件，导致背侧-外侧表面失效。由于半径似乎对载荷方向非常敏感，因此结果表明，尸体研究中观察到的断裂强度的大部分变异性可能归因于不同的边界条件。结果进一步表明，当福尔斯不可避免地跌倒在上肢时，集中于降低Colles骨折发生率的干预措施可能会受益于增加桡骨沿其轴向沿着的程度。
Distal radius (Colles’) fractures are a common fall-related injury in older adults and frequently result in long-term pain and reduced ability to perform activities of daily living. Because the occurrence of a fracture during a fall depends on both the strength of the bone and upon the kinematics and kinetics of the impact itself, we sought to understand how changes in bone mineral density (BMD) and loading direction affect the fracture strength and fracture initiation location in the distal radius. A three-dimensional finite element model of the radius, scaphoid, and lunate was used to examine changes of ±2% and ±4% BMD, and both axial and physiologically relevant off-axis loads on the radius. Changes in BMD resulted in similar percent changes in fracture strength. However, modifying the applied load to include dorsal and lateral components (assuming a dorsal view of the wrist, rather than an anatomic view) resulted in a 47% decrease in fracture strength (axial failure load: 2752N, off-axis: 1448N). Loading direction also influenced the fracture initiation site. Axially loaded radii failed on the medial surface immediately proximal to the styloid process. In contrast, off-axis loads, containing dorsal and lateral components, caused failure on the dorsal–lateral surface. Because the radius appears to be very sensitive to loading direction, the results suggest that much of the variability in fracture strength seen in cadaver studies may be attributed to varying boundary conditions. The results further suggest that interventions focused on reducing the incidence of Colles’ fractures when falls onto the upper extremities are unavoidable may benefit from increasing the extent to which the radius is loaded along its axis.