Abstract
Tripping is accompanied by reduced minimum toe clearance (mTC) during the swing phase of gait. The risk of fall due to tripping among transfemoral amputees is nearly 67% which is greater than the transtibial amputees. Therefore, intervention to improve mTC can potentially enhance the quality of life among transfemoral amputees. In this paper, we first develop a real-time visual feedback system with center of pressure (CoP) information. Next, we recruited six non-disabled and three transfemoral amputees to investigate the effect on mTC while participants were trained to shift the CoP anteriorly/posteriorly during heel strike. Finally, to assess the lasting effect of training on mTC, retention trials were conducted without feedback. During feedback, posterior shift in the CoP improved the mTC significantly from 4.68 ± 0.40 cm to 6.12 ± 0.68 cm (p < 0.025) in non-disabled participants. A similar significant improvement in mTC from 4.60 ± 0.55 cm to 5.62 ± 0.57 cm was observed in amputees during posterior shift of CoP. Besides mTC, maximal toe clearances, i.e., maxTC1 and maxTC2, also showed a significant increase (p < 0.025) during the posterior shift of CoP in both the participants. Moreover, during retention, mTC did not differ significantly (p > 0.05) from feedback condition in amputee, suggesting a positive effect of feedback training. The foot-to-ground angle (FGA) at mTC increased significantly (p < 0.025) during posterior shift feedback in non-disabled suggests active ankle dorsiflexion in increasing mTC. However, in amputees, FGA at mTC did not differ significantly during both anterior and posterior CoP shift feedback. The present findings suggest CoP feedback as a potential strategy during gait rehabilitation of transfemoral amputees.
Highlights
T RIPPING is a major cause of potential falls among lower limb amputees
Since a local minimum is required as the common measure outcomes of minimum toe clearance (mTC), it is important to be able to quantify foot clearance in cases where a local minimum of toe height does not exist
Two different mTC identification strategies were adopted to determine the value of mTC in strides with and without local minima. mTC was identified as a local minimum in the swing phase, which generally occurs during 34% to 64% of the swing phase segment [2]
Summary
T RIPPING is a major cause of potential falls among lower limb amputees. More than 50% of lower limb prosthetic users fall at least once a year [1]. It has been demonstrated that in able-bodied individuals, mTC is most sensitive to ankle dorsiflexion (3mm/degree), and mTC can be increased substantially by increasing the dorsiflexion angle at the ankle during the mid-swing phase [6] This approach has been translated to increase toe clearance in a transfemoral prosthesis, where researchers have been primarily focusing on the ankle dorsiflexion to enhance the mTC. The advanced motorized or hydraulic ankle can substantially enhance mTC through angular rotation of the ankle joint during the mid-swing phase [2], [7], [8] These advanced prosthetic designs have poor coordination capability between user and prosthesis [9] but are much expensive to be afforded by the people in developing countries. A potential strategy to enhance toe clearance is needed, which should be biomechanically appropriate and economically affordable
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