Abstract
Improved walking comfort has been linked with better bio-mimicking of the prosthetic ankle. This study investigated if a hydraulic ankle/foot can provide enough motion in both the sagittal and frontal planes during level and camber walking and if the hydraulic ankle/foot better mimics the biological ankle moment pattern compared with a fixed ankle/foot device. Five active male unilateral trans-femoral amputees performed level ground walking at normal and fast speeds and 2.5° camber walking in both directions using their own prostheses fitted with an “Echelon” hydraulic ankle/foot and an “Esprit” fixed ankle/foot. Ankle angles and the Trend Symmetry Index of the ankle moments were compared between prostheses and walking conditions. Significant differences between prostheses were found in the stance plantarflexion and dorsiflexion peaks with a greater range of motion being reached with the Echelon foot. The Echelon foot also showed significantly improved bio-mimicry of the ankle resistance moment in all walking conditions, either compared with the intact side of the same subject or with the “normal” mean curve from non-amputees. During camber walking, both types of ankle/foot devices showed similar changes in the frontal plane ankle angles. Results from a questionnaire showed the subjects were more satisfied with Echelon foot.
Highlights
Gait analysis is commonly used in the assessment of different prosthetic components to support the design, optimisation and selection of prostheses
Other methods that has been used to identify the gait asymmetry from the time curves of biomechanical variables include cross-correlation [25, 26] and region of deviation analysis [27, 28], The primary aim of this study is to evaluate the function of a hydraulic ankle-foot device on level and camber surface walking by comparison with a fixed ankle-foot device
The subject could deliberately reduce stride width to enable clean single foot contacts on both sides, as a “common” and “comfortable” walking condition was expected, we focused on clean single foot contacts from the prosthetic side only
Summary
Gait analysis is commonly used in the assessment of different prosthetic components to support the design, optimisation and selection of prostheses. There has been a series of gait studies on the functional performance of a clinically available ankle-foot hydraulic prosthetic device [1,2,3,4,5]. The hydraulic ankle-foot device is a passive single axis articulating design that allows custom control of the resisting moment. The gait from amputees with a hydraulic prosthetic ankle was compared with that using a fixed device and it was found that the hydraulic ankle/foot enabled decreased residual limb internal stresses, increased subjects’ self-selected walking speed, smoother and more rapid progression of prosthetic side plantar centre of pressure, and increased hip and knee joint power in both limbs [1,2,3,4].
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