Lower Limb Inter-Joint Coordination of Unilateral Transfemoral Amputees: Implications for Adaptation Control

Zhi Xu,Yu-Bo Fan,Tony Lin-Wei Chen,Duo Wai-Chi Wong,Ming Zhang,Wen-Tao Jiang,Fei Yan

doi:10.3390/app10124072

Abstract

The gait of transfemoral amputees can be made smoother by adjusting the inter-joint coordination of both lower limbs. In this study, we compared the inter-joint coordination of the amputated and non-amputated limbs of unilateral amputees to able-bodied controls. Eight amputees and eight able-bodied control participants were recruited. Walking speed, stance–swing time ratio, joint angle, joint angular velocity, and inter-joint coordination parameters—including continuous relative phase (CRP) and decomposition index (DI)—of the lower-limb joint pairs in stance and swing phases were investigated. Similarity of the CRP between groups was evaluated using cross-correlation measures and root-mean-square, and the variability of the CRP was examined by deviation phase (DP). There were significant differences between the amputated limbs and controls in CRP of hip–knee and knee–ankle in stance and swing, DP of knee–ankle and hip–ankle in stance, and DI of hip–knee in swing. For the non-amputated limbs, there were significant differences in CRP and DP of knee–ankle, and DI of hip–knee in swing compared to controls. The amputees utilized unique inter-joint coordination patterns for both limbs—particularly the hip joint—to compensate for the support-capability impairment due to limb salvage and ensure foot placement accuracy.

Highlights

The prosthetic gait is characterized by a relatively low walking speed [1], high asymmetry [2], and high metabolic cost [3]
Our findings revealed significant differences in the decomposition index (DI) for the majority of the comparisons, for the proximal joints
Unilateral transfemoral amputees utilized different inter-joint coordination patterns in the amputated and non-amputated limbs to ensure foot placement accuracy and compensate for the impaired support of the amputated side respectively, which was primarily regulated by adapting a higher degree of decomposition movement at the hip joints

Summary

Introduction

The prosthetic gait is characterized by a relatively low walking speed [1], high asymmetry [2], and high metabolic cost [3]. Concentric contraction of the hip flexors is needed to compensate for the loss of ankle plantar flexion for sufficient foot clearance [4]. During the single support phase, the ankle joint on the non-amputated side excessively plantarflexes to assist toe clearance [5]. Changes occur in the hip, knee, and ankle joints for both the amputated and. These were described as a compensatory mechanism, which is an explanation for the adaptation control strategy for amputees [5,6]

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Conclusion