A muscle-driven approach to restore stepping with an exoskeleton for individuals with paraplegia.
Sarah R Chang, Mark J Nandor, Lu Li and 7 others
PMID 28558835WHAT IT FOUND
Three men with motor complete spinal cord injury walked a lab walkway without prior practice using a new muscle-driven exoskeleton, but speeds were 0.03 to 0.06 m/s and Subjects B and C had poor knee flexion or foot drag.
Key findings
01All three participants walked with the self-contained system without prior practice.
02Walking speeds ranged from 0.03 to 0.06 m/s and step cadences were between 10 and 20 steps/min.
03Subject A had an average knee angle change of 43.6° ± 11.1° with sufficient foot-floor clearance, while Subjects B and C had 14.0° ± 4.9° and 19.2° ± 11.0° and difficulty achieving sufficient knee flexion.
STILL TO COME
How it was doneWhat they foundWhat it means for PTs
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What it does not show
The participants used the exoskeleton, neural stimulation, a walker, and a standby assist together, so the contribution of any single component cannot be separated. Only three male participants were tested, so the study cannot show how the system works for a wider group. The testing was done on a 10 m laboratory walkway, so it does not demonstrate independent walking. The paper reports relatively low walking speeds of 0.03 to 0.06 m/s and cadences of 10 to 20 steps/min. Subjects B and C had limited knee flexion, and Subject B often had foot drag during swing. The system depended on each participant's existing implanted, percutaneous, or surface stimulation setup, so it may not apply to people without such electrodes. The authors state that future systems will need power assist for long-distance walking because some muscles were unavailable or too weak.
Declared interests
The supplied funding declaration names the Rehabilitation Research and Development Service, the U.S. Department of Defense, and the National Institutes of Health.
The easy way to misread this
Do not read this as evidence that a muscle-driven exoskeleton restores practical community walking. Three men walked slowly in a lab with a walker and standby assist, and Subjects B and C had poor knee flexion or foot drag.