Institute of Biomedical Engineering, National Yang-Ming University, Taipei, Taiwan.
Med Eng Phys. 2010 Jul;32(6):623-9. doi: 10.1016/j.medengphy.2010.03.008. Epub 2010 May 1.
The fatigue failure of thermoplastic ankle-foot orthoses (AFOs) was observed in clinics. However, there was no standard evaluation for the AFOs to enhance the understanding of how AFOs become more readily acceptable to patients. Therefore, this study aimed to develop an ankle-foot simulator (AFS) as a testing apparatus for AFOs, and performed a pilot test to investigate the failure mechanism of anterior ankle-foot orthosis (AAFO). The accuracy and repeatability of the AFS during cyclic walking, cyclic stepping and cyclic stepping with the AAFO in sagittal plane were measured. The root mean square errors (RMSEs) of cyclic walking of AFS compared to a target gait data were less than 80.52N and 2.55 degrees in the vertical ground reaction force and in the kinematics, respectively. The RMSE of ankle plantarflexion and dorsiflexion of AFS in the cyclic stepping tests were less than 1.25 degrees. The repeatability was assessed by standard deviation, which were less than 9.46N and 0.72 degrees in all testing conditions. A typical failure progression of five AAFOs was observed and graded for four phases under cyclic stepping test. Failure always initiated at the junction of anterior tarsal bar and lateral (or medial) bar of the AAFOs, from which the rest failures were extended. It is suggested that this junction must be reinforced or prevented the stress concentration to elongate the endurance of AAFO.
在临床中观察到热塑性踝足矫形器（AFO）的疲劳失效。然而，目前还没有标准的评估方法来增强对 AFO 更易被患者接受的理解。因此，本研究旨在开发一种踝足模拟器（AFS）作为 AFO 的测试设备，并进行了一项初步试验，以研究前踝足矫形器（AAFO）的失效机制。测量了 AFS 在矢状面进行周期性步行、周期性跨步和带有 AAFO 的周期性跨步时的准确性和重复性。与目标步态数据相比，AFS 在周期性步行中的均方根误差（RMSE）在垂直地面反作用力和运动学方面均小于 80.52N 和 2.55 度。在周期性跨步测试中，AFS 的踝关节跖屈和背屈的 RMSE 小于 1.25 度。通过标准差评估重复性，在所有测试条件下均小于 9.46N 和 0.72 度。在周期性跨步测试中观察到五个 AAFO 的典型失效进展，并对其进行了四个阶段的分级。失效总是从 AAFO 的前跗骨杆和外侧（或内侧）杆的交界处开始，其余的失效从这里扩展。因此，建议必须加强这个交界处，或者防止应力集中，以延长 AAFO 的耐用性。
