Improving postural stability among people with lower-limb amputations by tactile sensory substitution

Abstract Background For people with lower-limb amputations, wearing a prosthetic limb helps restore their motor abilities for daily activities. However, the prosthesis's potential benefits are hindered by limited somatosensory feedback from the affected limb and its prosthesis. Previous studies...

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Autores principales:	Lijun Chen, Yanggang Feng, Baojun Chen, Qining Wang, Kunlin Wei
Formato:	article
Lenguaje:	EN
Publicado:	BMC 2021
Materias:	Sensory substitution Lower-limb amputation Postural control Intelligent prosthesis Neurosciences. Biological psychiatry. Neuropsychiatry RC321-571
Acceso en línea:	https://doaj.org/article/597d9560b2794d0491f23c7301e3627e
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spelling	oai:doaj.org-article:597d9560b2794d0491f23c7301e3627e2021-11-08T11:15:57ZImproving postural stability among people with lower-limb amputations by tactile sensory substitution10.1186/s12984-021-00952-x1743-0003https://doaj.org/article/597d9560b2794d0491f23c7301e3627e2021-11-01T00:00:00Zhttps://doi.org/10.1186/s12984-021-00952-xhttps://doaj.org/toc/1743-0003Abstract Background For people with lower-limb amputations, wearing a prosthetic limb helps restore their motor abilities for daily activities. However, the prosthesis's potential benefits are hindered by limited somatosensory feedback from the affected limb and its prosthesis. Previous studies have examined various sensory substitution systems to alleviate this problem; the prominent approach is to convert foot–ground interaction to tactile stimulations. However, positive outcomes for improving their postural stability are still rare. We hypothesized that the sensory substiution system based on surrogated tactile stimulus is capable of improving the standing stability among people with lower-limb amputations. Methods We designed a wearable device consisting of four pressure sensors and two vibrators and tested it among people with unilateral transtibial amputations (n = 7) and non-disabled participants (n = 8). The real-time measurements of foot pressure were fused into a single representation of foot–ground interaction force, which was encoded by varying vibration intensity of the two vibrators attached to the participants’ forearm. The vibration intensity followed a logarithmic function of the force representation, in keeping with principles of tactile psychophysics. The participants were tested with a classical postural stability task in which visual disturbances perturbed their quiet standing. Results With a brief familiarization of the system, the participants exhibited better postural stability against visual disturbances when switching on sensory substitution than without. The body sway was substantially reduced, as shown in head movements and excursions of the center of pressure. The improvement was present for both groups of participants and was particularly pronounced in more challenging conditions with larger visual disturbances. Conclusions Substituting otherwise missing foot pressure feedback with vibrotactile signals can improve postural stability for people with lower-limb amputations. The design of the mapping between the foot–ground interaction force and the tactile signals is essential for the user to utilize the surrogated tactile signals for postural control, especially for situations that their postural control is challenged.Lijun ChenYanggang FengBaojun ChenQining WangKunlin WeiBMCarticleSensory substitutionLower-limb amputationPostural controlIntelligent prosthesisNeurosciences. Biological psychiatry. NeuropsychiatryRC321-571ENJournal of NeuroEngineering and Rehabilitation, Vol 18, Iss 1, Pp 1-14 (2021)
institution	DOAJ
collection	DOAJ
language	EN
topic	Sensory substitution Lower-limb amputation Postural control Intelligent prosthesis Neurosciences. Biological psychiatry. Neuropsychiatry RC321-571
spellingShingle	Sensory substitution Lower-limb amputation Postural control Intelligent prosthesis Neurosciences. Biological psychiatry. Neuropsychiatry RC321-571 Lijun Chen Yanggang Feng Baojun Chen Qining Wang Kunlin Wei Improving postural stability among people with lower-limb amputations by tactile sensory substitution
description	Abstract Background For people with lower-limb amputations, wearing a prosthetic limb helps restore their motor abilities for daily activities. However, the prosthesis's potential benefits are hindered by limited somatosensory feedback from the affected limb and its prosthesis. Previous studies have examined various sensory substitution systems to alleviate this problem; the prominent approach is to convert foot–ground interaction to tactile stimulations. However, positive outcomes for improving their postural stability are still rare. We hypothesized that the sensory substiution system based on surrogated tactile stimulus is capable of improving the standing stability among people with lower-limb amputations. Methods We designed a wearable device consisting of four pressure sensors and two vibrators and tested it among people with unilateral transtibial amputations (n = 7) and non-disabled participants (n = 8). The real-time measurements of foot pressure were fused into a single representation of foot–ground interaction force, which was encoded by varying vibration intensity of the two vibrators attached to the participants’ forearm. The vibration intensity followed a logarithmic function of the force representation, in keeping with principles of tactile psychophysics. The participants were tested with a classical postural stability task in which visual disturbances perturbed their quiet standing. Results With a brief familiarization of the system, the participants exhibited better postural stability against visual disturbances when switching on sensory substitution than without. The body sway was substantially reduced, as shown in head movements and excursions of the center of pressure. The improvement was present for both groups of participants and was particularly pronounced in more challenging conditions with larger visual disturbances. Conclusions Substituting otherwise missing foot pressure feedback with vibrotactile signals can improve postural stability for people with lower-limb amputations. The design of the mapping between the foot–ground interaction force and the tactile signals is essential for the user to utilize the surrogated tactile signals for postural control, especially for situations that their postural control is challenged.
format	article
author	Lijun Chen Yanggang Feng Baojun Chen Qining Wang Kunlin Wei
author_facet	Lijun Chen Yanggang Feng Baojun Chen Qining Wang Kunlin Wei
author_sort	Lijun Chen
title	Improving postural stability among people with lower-limb amputations by tactile sensory substitution
title_short	Improving postural stability among people with lower-limb amputations by tactile sensory substitution
title_full	Improving postural stability among people with lower-limb amputations by tactile sensory substitution
title_fullStr	Improving postural stability among people with lower-limb amputations by tactile sensory substitution
title_full_unstemmed	Improving postural stability among people with lower-limb amputations by tactile sensory substitution
title_sort	improving postural stability among people with lower-limb amputations by tactile sensory substitution
publisher	BMC
publishDate	2021
url	https://doaj.org/article/597d9560b2794d0491f23c7301e3627e
work_keys_str_mv	AT lijunchen improvingposturalstabilityamongpeoplewithlowerlimbamputationsbytactilesensorysubstitution AT yanggangfeng improvingposturalstabilityamongpeoplewithlowerlimbamputationsbytactilesensorysubstitution AT baojunchen improvingposturalstabilityamongpeoplewithlowerlimbamputationsbytactilesensorysubstitution AT qiningwang improvingposturalstabilityamongpeoplewithlowerlimbamputationsbytactilesensorysubstitution AT kunlinwei improvingposturalstabilityamongpeoplewithlowerlimbamputationsbytactilesensorysubstitution
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Improving postural stability among people with lower-limb amputations by tactile sensory substitution

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