Shell Courtney E, Segal Ava D, Klute Glenn K, Neptune Richard R
Department of Mechanical Engineering, The University of Texas at Austin, Austin, TX 78712, USA.
Department of Veterans Affairs, Puget Sound Health Care System, Seattle, WA 98108, USA.
Clin Biomech (Bristol). 2017 Nov;49:56-63. doi: 10.1016/j.clinbiomech.2017.08.003. Epub 2017 Aug 15.
Little evidence exists regarding how prosthesis design characteristics affect performance in tasks that challenge mediolateral balance such as turning. This study assesses the influence of prosthetic foot stiffness on amputee walking mechanics and balance control during a continuous turning task.
Three-dimensional kinematic and kinetic data were collected from eight unilateral transtibial amputees as they walked overground at self-selected speed clockwise and counterclockwise around a 1-meter circle and along a straight line. Subjects performed the walking tasks wearing three different ankle-foot prostheses that spanned a range of sagittal- and coronal-plane stiffness levels.
A decrease in stiffness increased residual ankle dorsiflexion (10-13°), caused smaller adaptations (<5°) in proximal joint angles, decreased residual and increased intact limb body support, increased residual limb propulsion and increased intact limb braking for all tasks. While changes in sagittal-plane joint work due to decreased stiffness were generally consistent across tasks, effects on coronal-plane hip work were task-dependent. When the residual limb was on the inside of the turn and during straight-line walking, coronal-plane hip work increased and coronal-plane peak-to-peak range of whole-body angular momentum decreased with decreased stiffness.
Changes in sagittal-plane kinematics and kinetics were similar to those previously observed in straight-line walking. Mediolateral balance improved with decreased stiffness, but adaptations in coronal-plane angles, work and ground reaction force impulses were less systematic than those in sagittal-plane measures. Effects of stiffness varied with the residual limb inside versus outside the turn, which suggests that actively adjusting stiffness to turn direction may be beneficial.
关于假体设计特征如何影响诸如转弯等挑战内外侧平衡任务的表现，现有证据很少。本研究评估了假肢足部刚度对截肢者在连续转弯任务中的步行力学和平衡控制的影响。
从八名单侧胫骨截肢者身上收集三维运动学和动力学数据，他们以自选速度在地面上顺时针和逆时针绕1米的圆圈行走以及沿直线行走。受试者穿着三种不同的踝足假肢进行步行任务，这些假肢在矢状面和冠状面的刚度水平范围不同。
刚度降低会增加残余踝关节背屈（10 - 13°），导致近端关节角度的适应性变化较小（<5°），减少残余肢体支撑并增加健全肢体支撑，增加残余肢体推进力并增加健全肢体制动力。虽然由于刚度降低导致的矢状面关节功变化在所有任务中总体上是一致的，但对冠状面髋关节功的影响则取决于任务。当残余肢体在转弯内侧和直线行走时，随着刚度降低，冠状面髋关节功增加，全身角动量的冠状面峰峰值范围减小。
矢状面运动学和动力学的变化与之前在直线行走中观察到的相似。刚度降低可改善内外侧平衡，但冠状面角度、功和地面反作用力脉冲的适应性变化不如矢状面测量那样系统。刚度的影响因残余肢体在转弯内侧还是外侧而异，这表明根据转弯方向主动调整刚度可能是有益的。
