Bowersock Collin D, Tagoe Emmanuella A, Hopkins Samuel, Fang Shanpu, Lerner Zachary F
Oklahoma State University, Human Performance and Nutrition Research Institute, Stillwater, OK, USA.
Northern Arizona University, Mechanical Engineering, Flagstaff, AZ, USA.
Ann Biomed Eng. 2025 Jul 14. doi: 10.1007/s10439-025-03773-4.
This study explored the effectiveness of a novel differential and adjustable stiffness leaf spring AFO (DAS-AFO) during standing, walking, and sit-to-stand tasks among individuals with cerebral palsy.
Eleven individuals with cerebral palsy, ages 12-41, completed treadmill walking trials with the DAS-AFO, a solid (i.e., rigid) AFO, and without an assistive device (shod). We quantified metabolic cost, muscle activity of the soleus and vastus lateralis, and lower body kinetics and kinematics. Participants also performed overground walking, sit-to-stand, and stable standing tasks while wearing the DAS-AFO and reported their preferred stiffness setting for each task. Additionally, we quantified center of pressure during the stable standing task.
Walking with the DAS-AFO resulted in an average 24% increase in ankle push-off power when compared to the solid AFO (p = .003). Both AFO conditions resulted in an average 16% reduction in soleus activity compared to shod (p < .040); only the DAS-AFO reduced vastus lateralis activity compared to shod (13% average reduction, p = .015). Over half of the participants preferred a different AFO stiffness for at least one of the tasks of daily living. No stiffness setting was universally preferred for a single task. During the stable standing task, the high stiffness setting increased average anterior-posterior center of pressure excursion (p = .022) and velocity (p = .001) compared to shod.
Our findings highlight potential benefits of the DAS-AFO design over solid AFOs, including improved ankle joint motions and push-off power during walking. Customizability of the DAS-AFO positively influenced participant preference and task performance.
本研究探讨了一种新型的可变刚度叶片弹簧式踝足矫形器（DAS-AFO）在脑瘫患者站立、行走和从坐到站任务中的有效性。
11名年龄在12至41岁之间的脑瘫患者，分别穿着DAS-AFO、坚固（即刚性）踝足矫形器以及不使用辅助装置（仅穿鞋）完成跑步机行走试验。我们对代谢成本、比目鱼肌和股外侧肌的肌肉活动以及下半身的动力学和运动学进行了量化。参与者还在佩戴DAS-AFO的情况下进行了地面行走、从坐到站和稳定站立任务，并报告了他们对每项任务的首选刚度设置。此外，我们对稳定站立任务期间的压力中心进行了量化。
与坚固踝足矫形器相比，使用DAS-AFO行走时踝关节蹬离功率平均增加了24%（p = 0.003）。与仅穿鞋相比，两种踝足矫形器条件下比目鱼肌活动平均降低了16%（p < 0.040）；与仅穿鞋相比，只有DAS-AFO降低了股外侧肌活动（平均降低13%，p = 0.015）。超过一半的参与者在至少一项日常生活任务中更喜欢不同的踝足矫形器刚度。没有一种刚度设置在单一任务中是普遍首选的。在稳定站立任务期间，与仅穿鞋相比，高刚度设置增加了平均前后压力中心偏移（p = 0.022）和速度（p = 0.001）。
我们的研究结果突出了DAS-AFO设计相对于坚固踝足矫形器的潜在益处，包括行走过程中改善踝关节运动和蹬离功率。DAS-AFO的可定制性对参与者的偏好和任务表现产生了积极影响。
