Author: Xu, Zhi
Title: Biomechanical study of gait coordination of transfemoral amputees
Advisors: Zhang, Ming (BME)
Degree: Ph.D.
Year: 2021
Subject: Prosthesis
Amputees -- Rehabilitation
Gait in humans
Gait disorders
Hong Kong Polytechnic University -- Dissertations
Department: Department of Biomedical Engineering
Pages: xxv, 212 pages : illustrations
Language: English
Abstract: Transfemoral amputees' rehabilitation presents difficulties owing to the extensive loss of joints and muscles. Wearing a transfemoral prosthesis is a necessity for amputees to restore bipedal locomotion ability. Nevertheless, the prostheses still fall short of compensating the lost biomechanical function because of the scarce knowledge of amputees' gait coordination. Therefore, the overall objective of this study was to better understand the gait coordination of transfemoral amputees and its implication in rehabilitation and prosthesis design. The scope of the study included investigating transfemoral amputees' gait coordination of lower limbs, and studying the effects of the prosthetic knee-ankle coupling designed mechanism and walking speed on gait coordination patterns. Our first study investigated the gait coordination of unilateral transfemoral amputees and compared to abled persons. The results suggested that amputees adopt a different gait coordination pattern to achieve the specific prosthetic gait requirements. The gait coordination analysis demonstrated its sensitiveness in detecting gait deviation by studying the coordination between joints rather than studying each joint separately. The second study compared the gait coordination of transfemoral amputees wearing traditional prostheses and the knee-ankle coupling designed prosthesis. The latter prosthesis guaranteed better gait compliance through ankle dorsiflexion and plantarflexion, while the prosthetic knee showed a function similar to that of the traditional prostheses. The coupling designed mechanism exhibits advantages in improving gait coordination, but there is still room for improving the prosthetic knee extension function to induce a better gait. In the third study, transfemoral amputees walked at different speeds. The gait coordination was less adjustable in response to slow speed, which gives us another explanation for the amputees' low walking speed. The preferred speed was the "optimal" speed at which the motion demonstrated higher flexibility. The prosthetic knee and ankle displayed weak adaptability to different walking speeds, whereas the hip joints played an essential role for control adjustment when coping with different speeds. The fourth study compared the muscle coordination between non-amputated limbs and the limbs of abled persons through inverse dynamics simulation. The realignment of muscle coordination pattern was the main means to satisfy the specific joint moment requirement of non-amputated limbs. In addition, transfemoral amputees were found to hyperextend their intact knees during stance, which may be the cause of knee osteoarthritis. We also compared the maximum forces of each muscle and found muscle disuse in non-amputated limbs. In conclusion, the gait coordination of transfemoral amputees differs from that in abled persons. These differences in gait coordination embody deficiencies in motion control ability along with defects of prosthesis. The gait coordination analysis demonstrated advantages in its multi-level research, namely from joints to joints and muscles to muscles, thus it is more sensitive in detecting gait deviation. The findings could be beneficial in interpreting the secondary pathology of transfemoral amputees and giving another insight into the ways of improving rehabilitation programs and prosthesis design.
Rights: All rights reserved
Access: open access

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