Differences in muscle synergies between healthy subjects and transfemoral amputees during normal transient-state walking speed

Pouyan Mehryar; Mohammad S Shourijeh; Tahmineh Rezaeian; Amin R Khandan; Neil Messenger; Rory O'Connor; Farzam Farahmand; Abbas Dehghani-Sanij

doi:10.1016/j.gaitpost.2019.10.034

Differences in muscle synergies between healthy subjects and transfemoral amputees during normal transient-state walking speed

Gait Posture. 2020 Feb:76:98-103. doi: 10.1016/j.gaitpost.2019.10.034. Epub 2019 Nov 8.

Authors

Pouyan Mehryar¹, Mohammad S Shourijeh², Tahmineh Rezaeian³, Amin R Khandan⁴, Neil Messenger³, Rory O'Connor⁵, Farzam Farahmand⁴, Abbas Dehghani-Sanij⁶

Affiliations

¹ Institute of Design, Robotic, and Optimisation, Department of Mechanical Engineering, The University of Leeds, Leeds, UK. Electronic address: mnpm@leeds.ac.uk.
² Department of Mechanical Engineering, The Rice University, Texas, USA.
³ School of Biomedical sciences, Faculty of Biological Sciences, The University of Leeds, Leeds, UK.
⁴ Faculty of Mechanical Engineering, Sharif University of Technology, Tehran, Iran.
⁵ School of Medicine, Faculty of Medicine and Health, The University of Leeds, Leeds, UK.
⁶ Institute of Design, Robotic, and Optimisation, Department of Mechanical Engineering, The University of Leeds, Leeds, UK.

PMID: 31751916
DOI: 10.1016/j.gaitpost.2019.10.034

Abstract

Background: Lower limb amputation is a major public health issue globally, and its prevalence is increasing significantly around the world. Previous studies on lower limb amputees showed analogous complexity implemented by the neurological system which does not depend on the level of amputation.

Research question: What are the differences in muscle synergies between healthy subjects (HS) and transfemoral amputees (TFA) during self-selected normal transient-state walking speed?

Methods: thirteen male HS and eleven male TFA participated in this study. Surface electromyography (sEMG) data were collected from HS dominant leg and TFA intact limb. Concatenated non-negative matrix factorization (CNMF) was used to extract muscle synergy components synergy vectors (S) and activation coefficient profiles (C). Correlation between a pair of synergy vectors from HS and TFA was analyzed by means of the coefficient of determination (R²). Statistical parametric mapping (SPM) was used to compare the temporal components of the muscle synergies between groups.

Results: the highest correlation was perceived in synergy 2 (S2) and 3 (S3) and the lowest in synergy 1 (S1) and 4 (S4) between HS and TFA. Statistically significant differences were observed in all of the activation coefficients, particularly during the stance phase. Significant lag in the activation coefficient of S2 (due mainly to activated plantarflexors) resulted in a statistically larger portion of the gait cycle (GC) in stance phase in TFA.

Significance: Understanding the activation patterns of lower limb amputees' muscles that control their intact leg (IL) and prosthetic leg (PL) joints could lead to greater knowledge of neuromuscular compensation strategies in amputees. Studying the low-dimensional muscle synergy patterns in the lower limbs can further this understanding. The findings in this study could contribute to improving gait rehabilitation of lower limb amputees and development of the new generation of prostheses.

Keywords: Muscle synergy/modular motor control; Non-amputees/healthy; Non-negative matrix factorization; Statistical parametric mapping; Surface electromyography; Transfemoral/above knee amputees; Transient-state gait.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Adult
Amputation, Surgical*
Amputees / rehabilitation
Artificial Limbs*
Biomechanical Phenomena
Case-Control Studies
Electromyography
Female
Femur / surgery*
Gait / physiology
Humans
Male
Middle Aged
Muscle, Skeletal / physiology*
Walking Speed*

Grants and funding

DH_/Department of Health/United Kingdom