Usability and performance validation of an ultra-lightweight and versatile untethered robotic ankle exoskeleton.
Greg Orekhov, Ying Fang, Chance F Cuddeback and 1 others
PMID 34758857WHAT IT FOUND
A lightweight untethered ankle exoskeleton reduced energy cost during incline walking in healthy adults and increased stair-climbing distance in people with cerebral palsy.
Users could don and calibrate the device independently in under five minutes.
Key findings
01In healthy adults, the exoskeleton improved metabolic power during incline walking by 9.9% on average, with five of six participants showing benefit.
02In participants with cerebral palsy who completed the test, the device increased the number of floors climbed during maximal exertion by 38.4% compared to walking unassisted.
03Participants with cerebral palsy could don and set up the device without researcher help in an average of 3.5 minutes after practice, receiving an 'excellent' usability rating.
STILL TO COME
How it was doneWhat they foundWhat it means for PTsWhat it means for OTs
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What it does not show
Very small sample sizes (n=6 healthy, n=5/7 impaired) limit the generalizability of the findings. Two participants with cerebral palsy could not complete the stair-climbing test due to low body mass, excluding them from performance data. The battery life lasted only 37 minutes at the average torque used, insufficient for all-day community use. The study did not include a blinding or sham condition, so placebo effects or adaptation to the device cannot be ruled out. Metabolic cost did not decrease in the cerebral palsy group during maximal exertion, meaning the benefit was in distance achieved, not efficiency.
Declared interests
Funding was provided by the National Center for Medical Rehabilitation Research (NIH). The authors did not declare any financial conflicts of interest.
The easy way to misread this
Do not assume the device makes walking feel easier for patients with cerebral palsy during high-intensity tasks. While they climbed more floors, their perceived exertion and metabolic power remained similar to unassisted walking, meaning they worked just as hard to achieve greater distance.