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Neuromuscular adaptations and sensorimotor integration following a unilateral transfemoral amputation

BACKGROUND: Following an amputation, the human postural control system develops neuromuscular adaptations to regain an effective postural control. We investigated the compensatory mechanisms behind these adaptations and how sensorimotor integration is affected after a lower-limb transfemoral amputat...

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Autores principales: Claret, Claudia Ramos, Herget, Georg W., Kouba, Lukas, Wiest, Daniel, Adler, Jochen, von Tscharner, Vinzenz, Stieglitz, Thomas, Pasluosta, Cristian
Formato: Online Artículo Texto
Lenguaje:English
Publicado: BioMed Central 2019
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6744715/
https://www.ncbi.nlm.nih.gov/pubmed/31521190
http://dx.doi.org/10.1186/s12984-019-0586-9
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author Claret, Claudia Ramos
Herget, Georg W.
Kouba, Lukas
Wiest, Daniel
Adler, Jochen
von Tscharner, Vinzenz
Stieglitz, Thomas
Pasluosta, Cristian
author_facet Claret, Claudia Ramos
Herget, Georg W.
Kouba, Lukas
Wiest, Daniel
Adler, Jochen
von Tscharner, Vinzenz
Stieglitz, Thomas
Pasluosta, Cristian
author_sort Claret, Claudia Ramos
collection PubMed
description BACKGROUND: Following an amputation, the human postural control system develops neuromuscular adaptations to regain an effective postural control. We investigated the compensatory mechanisms behind these adaptations and how sensorimotor integration is affected after a lower-limb transfemoral amputation. METHODS: Center of pressure (CoP) data of 12 unilateral transfemoral amputees and 12 age-matched able-bodied subjects were recorded during quiet standing with eyes open (EO) and closed (EC). CoP adjustments under each leg were recorded to study their contribution to posture control. The spatial structure of the CoP displacements was characterized by measuring the mean distance, the mean velocity of the CoP adjustments, and the sway area. The Entropic Half-Life (EnHL) quantifies the temporal structure of the CoP adjustments and was used to infer disrupted sensory feedback loops in amputees. We expanded the analysis with measures of weight-bearing imbalance and asymmetry, and with two standardized balance assessments, the Berg Balance Scale (BBS) and Timed Up-and-Go (TUG). RESULTS: There was no difference in the EnHL values of amputees and controls when combining the contributions of both limbs (p = 0.754). However, amputees presented significant differences between the EnHL values of the intact and prosthetic limb (p <  0.001). Suppressing vision reduced the EnHL values of the intact (p = 0.001) and both legs (p = 0.028), but not in controls. Vision feedback in amputees also had a significant effect (increase) on the mean CoP distance (p <  0.001), CoP velocity (p <  0.001) and sway area (p = 0.007). Amputees presented an asymmetrical stance. The EnHL values of the intact limb in amputees were positively correlated to the BBS scores (EO: ρ = 0.43, EC: ρ = 0.44) and negatively correlated to the TUG times (EO: ρ = − 0.59, EC: ρ = − 0.69). CONCLUSION: These results suggest that besides the asymmetry in load distribution, there exist neuromuscular adaptations after an amputation, possibly related to the loss of sensory feedback and an altered sensorimotor integration. The EnHL values suggest that the somatosensory system predominates in the control of the intact leg. Further, suppressing the visual system caused instability in amputees, but had a minimal impact on the CoP dynamics of controls. These findings points toward the importance of providing somatosensory feedback in lower-limb prosthesis to reestablish a normal postural control. TRIAL REGISTRATION: DRKS00015254, registered on September 20th, 2018.
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spelling pubmed-67447152019-09-18 Neuromuscular adaptations and sensorimotor integration following a unilateral transfemoral amputation Claret, Claudia Ramos Herget, Georg W. Kouba, Lukas Wiest, Daniel Adler, Jochen von Tscharner, Vinzenz Stieglitz, Thomas Pasluosta, Cristian J Neuroeng Rehabil Research BACKGROUND: Following an amputation, the human postural control system develops neuromuscular adaptations to regain an effective postural control. We investigated the compensatory mechanisms behind these adaptations and how sensorimotor integration is affected after a lower-limb transfemoral amputation. METHODS: Center of pressure (CoP) data of 12 unilateral transfemoral amputees and 12 age-matched able-bodied subjects were recorded during quiet standing with eyes open (EO) and closed (EC). CoP adjustments under each leg were recorded to study their contribution to posture control. The spatial structure of the CoP displacements was characterized by measuring the mean distance, the mean velocity of the CoP adjustments, and the sway area. The Entropic Half-Life (EnHL) quantifies the temporal structure of the CoP adjustments and was used to infer disrupted sensory feedback loops in amputees. We expanded the analysis with measures of weight-bearing imbalance and asymmetry, and with two standardized balance assessments, the Berg Balance Scale (BBS) and Timed Up-and-Go (TUG). RESULTS: There was no difference in the EnHL values of amputees and controls when combining the contributions of both limbs (p = 0.754). However, amputees presented significant differences between the EnHL values of the intact and prosthetic limb (p <  0.001). Suppressing vision reduced the EnHL values of the intact (p = 0.001) and both legs (p = 0.028), but not in controls. Vision feedback in amputees also had a significant effect (increase) on the mean CoP distance (p <  0.001), CoP velocity (p <  0.001) and sway area (p = 0.007). Amputees presented an asymmetrical stance. The EnHL values of the intact limb in amputees were positively correlated to the BBS scores (EO: ρ = 0.43, EC: ρ = 0.44) and negatively correlated to the TUG times (EO: ρ = − 0.59, EC: ρ = − 0.69). CONCLUSION: These results suggest that besides the asymmetry in load distribution, there exist neuromuscular adaptations after an amputation, possibly related to the loss of sensory feedback and an altered sensorimotor integration. The EnHL values suggest that the somatosensory system predominates in the control of the intact leg. Further, suppressing the visual system caused instability in amputees, but had a minimal impact on the CoP dynamics of controls. These findings points toward the importance of providing somatosensory feedback in lower-limb prosthesis to reestablish a normal postural control. TRIAL REGISTRATION: DRKS00015254, registered on September 20th, 2018. BioMed Central 2019-09-14 /pmc/articles/PMC6744715/ /pubmed/31521190 http://dx.doi.org/10.1186/s12984-019-0586-9 Text en © The Author(s). 2019 Open AccessThis article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.
spellingShingle Research
Claret, Claudia Ramos
Herget, Georg W.
Kouba, Lukas
Wiest, Daniel
Adler, Jochen
von Tscharner, Vinzenz
Stieglitz, Thomas
Pasluosta, Cristian
Neuromuscular adaptations and sensorimotor integration following a unilateral transfemoral amputation
title Neuromuscular adaptations and sensorimotor integration following a unilateral transfemoral amputation
title_full Neuromuscular adaptations and sensorimotor integration following a unilateral transfemoral amputation
title_fullStr Neuromuscular adaptations and sensorimotor integration following a unilateral transfemoral amputation
title_full_unstemmed Neuromuscular adaptations and sensorimotor integration following a unilateral transfemoral amputation
title_short Neuromuscular adaptations and sensorimotor integration following a unilateral transfemoral amputation
title_sort neuromuscular adaptations and sensorimotor integration following a unilateral transfemoral amputation
topic Research
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6744715/
https://www.ncbi.nlm.nih.gov/pubmed/31521190
http://dx.doi.org/10.1186/s12984-019-0586-9
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