Muscle Synergy Analysis in Transtibial Amputee during Ramp Descending Activity

The highest number of amputees are elderly transtibial in developed countries. Walking on inclined surfaces is a crucial activity. The aim of this study was to investigate the difference in healthy, elderly amputee’s intact (IL) as well as prosthetic leg (PL) using muscle synergy analysis. Non-negative matrix factorization (NNMF) was performed to divide the surface electromyographic (sEMG) data obtained from 6 upper knee and 4 shank muscles into muscle synergy (S) and activation coefficient profile (C) during ramp descending (RD) activity. S comparison showed a reasonable correlation in healthy and amputee groups. This suggests synergistic activation of the same group of muscles by the central nervous system (CNS). However, C showed to be statistically significantly different in some regions of the amputee’s gait cycle (GC). The difference could be resulted by muscles alteration due to lack of force tolerance and proprioceptive feedback from PL as well as the type of prosthesis used by the amputee. This information will be useful in future development of myoelectric prostheses and rehabilitation.