Munaretto Joseph M, McNitt-Gray Jill L, Flashner Henryk, Requejo Philip S
Department of Biomedical Engineering, University of Southern California, Los Angeles, CA 90089, USA.
Clin Biomech (Bristol). 2012 Mar;27(3):255-62. doi: 10.1016/j.clinbiomech.2011.10.001. Epub 2011 Nov 8.
Manual wheelchair propulsion is associated with overuse injuries of the shoulder. Reaction force redirection relative to upper extremity segments was hypothesized as a means to redistribute mechanical load imposed on the upper extremity without decrements in wheelchair propulsion performance.
Two individuals performed wheelchair propulsion under simulated inclined (graded) conditions using self-selected control strategies. Upper extremity kinematics and reaction forces applied to the wheel were quantified and used as input into an experiment-based multi-link inverse dynamics model that incorporates participant-specific experimental results. Reaction force direction was systematically modified to determine the mechanical demand imposed on the upper extremity (elbow and shoulder net joint moments and net joint forces) during wheelchair propulsion. Results were presented as solution spaces to examine the upper extremity load distribution characteristics within and between participants across a range of reaction force directions.
Redirection of the reaction force relative to the upper extremity segments provides multiple solutions for redistributing mechanical demand across the elbow and shoulder without decrements in manual wheelchair propulsion performance. The distribution of load across RF directions was participant specific and was found to vary with time during the push phase.
Solution spaces provide a mechanical basis for individualized interventions that aim to maintain function and redistribute load away from structures at risk for injury (e.g. reduce demand imposed on shoulder flexors (reduce shoulder net joint moment) or reduce potential for impingement (reduce shoulder net joint force).
手动轮椅推进与肩部过度使用损伤有关。相对于上肢节段的反作用力重定向被假设为一种在不降低轮椅推进性能的情况下重新分配施加在上肢的机械负荷的方法。
两名受试者在模拟倾斜（分级）条件下使用自行选择的控制策略进行轮椅推进。对上肢运动学和施加在车轮上的反作用力进行量化，并将其用作基于实验的多连杆逆动力学模型的输入，该模型纳入了受试者特定的实验结果。系统地改变反作用力方向，以确定轮椅推进过程中施加在上肢（肘部和肩部净关节力矩和净关节力）上的机械需求。结果以解空间的形式呈现，以检查在一系列反作用力方向上受试者内部和之间的上肢负荷分布特征。
相对于上肢节段的反作用力重定向为在不降低手动轮椅推进性能的情况下，在肘部和肩部重新分配机械需求提供了多种解决方案。跨反作用力方向的负荷分布因受试者而异，并且在推进行程中随时间变化。
解空间为个体化干预提供了机械学基础，这些干预旨在维持功能并将负荷从有受伤风险的结构上重新分配（例如，减少施加在肩部屈肌上的需求（减少肩部净关节力矩）或减少撞击的可能性（减少肩部净关节力））。
