North Carolina State University, 911 Oval Drive, Raleigh, NC, USA.
University of North Carolina at Chapel Hill, Chapel Hill, NC, USA.
J Neuroeng Rehabil. 2021 Feb 1;18(1):21. doi: 10.1186/s12984-021-00812-8.
Weakness of ankle and knee musculature following injury or disorder results in reduced joint motion associated with metabolically expensive gait compensations to enable limb support and advancement. However, neuromechanical coupling between the ankle and knee make it difficult to discern independent roles of these restrictions in joint motion on compensatory mechanics and metabolic penalties.
We sought to determine relative impacts of ankle and knee impairment on compensatory gait strategies and energetic outcomes using an unimpaired cohort (N = 15) with imposed unilateral joint range of motion restrictions as a surrogate for reduced motion resulting from gait pathology. Participants walked on a dual-belt instrumented treadmill at 0.8 m s using a 3D printed ankle stay and a knee brace to systematically limit ankle motion (restricted-ank), knee motion (restricted-knee), and ankle and knee motion (restricted-a + k) simultaneously. In addition, participants walked without any ankle or knee bracing (control) and with knee bracing worn but unrestricted (braced).
When ankle motion was restricted (restricted-ank, restricted-a + k) we observed decreased peak propulsion relative to the braced condition on the restricted limb. Reduced knee motion (restricted-knee, restricted-a + k) increased restricted limb circumduction relative to the restricted-ank condition through ipsilateral hip hiking. Interestingly, restricted limb average positive hip power increased in the restricted-ank condition but decreased in the restricted-a + k and restricted-knee conditions, suggesting that locking the knee impeded hip compensation. As expected, reduced ankle motion, either without (restricted-ank) or in addition to knee restriction (restricted-a + k) yielded significant increase in net metabolic rate when compared with the braced condition. Furthermore, the relative increase in metabolic cost was significantly larger with restricted-a + k when compared to restricted-knee condition.
Our methods allowed for the reproduction of asymmetric gait characteristics including reduced propulsive symmetry and increased circumduction. The metabolic consequences bolster the potential energetic benefit of targeting ankle function during rehabilitation.
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受伤或患病后脚踝和膝关节肌肉力量减弱，导致关节活动度减小，为了支撑和推动肢体，代偿性步态需要更多的代谢能量。然而，脚踝和膝关节的神经肌肉耦合使得很难区分这些限制对关节运动、代偿力学和代谢惩罚的独立作用。
我们试图通过使用未受损的队列（N=15）来确定脚踝和膝关节损伤对代偿步态策略和能量消耗的相对影响，该队列采用 3D 打印的脚踝固定器和膝盖支具来限制脚踝运动（限制脚踝）、膝盖运动（限制膝盖）和脚踝和膝盖运动（同时限制脚踝和膝盖），以模拟因步态病理而导致的运动受限。参与者在双带式仪器化跑步机上以 0.8 m/s 的速度行走，使用 3D 打印的脚踝固定器和膝盖支具来系统地限制脚踝运动（限制脚踝）、膝盖运动（限制膝盖）和脚踝和膝盖运动（同时限制脚踝和膝盖）。此外，参与者在没有脚踝或膝盖支具的情况下（对照）和佩戴膝盖支具但不限制（支具）的情况下行走。
当脚踝运动受到限制（限制脚踝、限制脚踝和膝盖）时，与支具状态相比，受限肢体的峰值推进力降低。当膝盖运动受到限制（限制膝盖、限制脚踝和膝盖）时，通过同侧髋关节摆动，限制肢体的环转运动增加。有趣的是，限制脚踝的情况下，限制肢体的平均正髋力增加，但在限制脚踝和膝盖的情况下，限制肢体的平均正髋力减少，这表明锁定膝盖会阻碍髋关节代偿。正如预期的那样，与支具状态相比，无论是否限制膝盖（限制脚踝），限制脚踝运动都会显著增加净代谢率。此外，与限制膝盖相比，限制脚踝和膝盖的情况下，代谢成本的相对增加显著更大。
我们的方法允许复制不对称的步态特征，包括降低推进力的对称性和增加环转运动。代谢结果支持在康复过程中针对脚踝功能的潜在能量效益。
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