Center for the Intrepid, Department of Rehabilitation Medicine, Brooke Army Medical Center, JBSA Ft, Sam Houston, TX, USA.
Extremity Trauma and Amputation Center of Excellence, JBSA Ft, Sam Houston, TX, USA.
J Neuroeng Rehabil. 2018 Nov 21;15(1):111. doi: 10.1186/s12984-018-0455-y.
Ankle-foot orthoses (AFO) are commonly prescribed to provide functional assistance for patients with lower limb injuries or weakness. Their passive mechanical elements can provide some energy return to improve walking ability, but cannot restore plantar flexor push-off. Powered AFOs provide an assistive torque about the ankle to address the limitations of passive devices, but current designs have yet to be implemented on a large scale clinically.
To compare passive AFOs to a new untethered, powered AFO design in a clinical population with lower limb reconstruction.
A crossover study design, conducted on three individuals with lower limb reconstruction, compared gait mechanics at a standardized speed (based on leg length) in 4 AFO conditions: 1. None (shoes only), 2. Blue Rocker (BR, Allard, USA), 3. Intrepid Dynamic Exoskeletal Orthosis (IDEO), and 4. PowerFoot Orthosis (PFO BionX Medical Technologies, Inc.). The PFO was a custom, battery-powered device whose damping and power were capable to being tuned to meet patient needs. Subjects performed biomechanical gait analysis and metabolic testing at slow, moderate and fast speeds. Dependent variables included total limb power (calculated using a unified deformable segment model), mechanical work, mechanical efficiency, ankle motion, net metabolic cost across three speeds, and performance measures were calculated. Effect sizes (d) were calculated and d > 0.80 denoted a large effect.
Net positive work (d > 1.17) and efficiency (d > 1.43) were greatest in the PFO. There were large effects for between limb differences in positive work for all conditions except the PFO (d = 0.75). The PFO normalized efficiency between the affected and unaffected limbs (d = 0.50), whereas efficiency was less on the affected limb for all other conditions (d > 1.69). Metabolic rate was not consistently lowest in any one AFO condition across speeds. Despite some positive results of the PFO, patient preferred their daily use AFO (2 IDEO, 1 BR). All participants indicated that mass and size were concerns with using the PFO.
A novel PFO resulted in more biomimetic mechanical work and efficiency than commercially-available and custom passive AFO models. Although the powered AFO provided some biomechanical benefits, further improvements are warranted to improve patient satisfaction.
踝足矫形器（AFO）常用于为下肢受伤或虚弱的患者提供功能辅助。其被动机械元件可以提供一些能量回收，以改善行走能力，但不能恢复跖屈肌的蹬离。动力 AFO 可在踝关节周围提供辅助扭矩，以解决被动装置的局限性，但目前的设计尚未在临床上大规模实施。
在下肢重建的临床人群中，比较被动 AFO 与新型无绳动力 AFO 设计。
采用交叉研究设计，对 3 名下肢重建患者进行研究，在 4 种 AFO 条件下比较标准化速度（基于腿长）的步态力学：1. 无（仅穿鞋），2. Blue Rocker（BR，Allard，美国），3. Intrepid Dynamic Exoskeletal Orthosis（IDEO）和 4. PowerFoot Orthosis（PFO BionX Medical Technologies，Inc.）。PFO 是一种定制的、电池供电的设备，其阻尼和功率可进行调整以满足患者的需求。受试者在慢、中、快三种速度下进行生物力学步态分析和代谢测试。因变量包括总肢体功率（使用统一的可变形节段模型计算）、机械功、机械效率、踝关节运动、三种速度下的净代谢成本以及性能指标。计算效应量（d），d>0.80 表示具有较大影响。
在 PFO 中，净正功（d>1.17）和效率（d>1.43）最大。除 PFO 外，所有条件下两腿之间的正功差异均具有较大影响（d=0.75）。PFO 使患侧和健侧的效率正常化（d=0.50），而所有其他条件下患侧的效率较低（d>1.69）。代谢率在任何一种 AFO 条件下都不是在任何速度下都最低。尽管 PFO 有一些积极的结果，但患者更喜欢他们日常使用的 AFO（2 IDEO，1 BR）。所有参与者都表示，质量和尺寸是使用 PFO 的关注点。
与市售和定制的被动 AFO 模型相比，新型 PFO 产生的机械工作和效率更具仿生特性。尽管动力 AFO 提供了一些生物力学益处，但仍需要进一步改进以提高患者满意度。
