Modulation of anticipatory postural adjustments using a powered ankle orthosis in people with Parkinson's disease and freezing of gait.
Matthew N Petrucci, Colum D MacKinnon, Elizabeth T Hsiao-Wecksler
PMID 31226601WHAT IT FOUND
Wearing a powered ankle orthosis made the body's preparatory movements before stepping larger, faster, and more consistent in people with Parkinson's disease and freezing of gait.
Adding an acoustic cue to the device produced the strongest improvements in these balance shifts.
Key findings
01The powered ankle orthosis significantly increased the magnitude of the vertical force applied to the floor during the preparatory phase of stepping compared to baseline conditions.
02Mechanical assistance from the orthosis significantly reduced the trial-to-trial variability of the preparatory force and the time it took to lift the foot off the ground.
03Combining the acoustic cue with the powered orthosis resulted in the largest increases in force and lateral weight shifts, outperforming the cue alone or the device alone.
STILL TO COME
How it was doneWhat they foundWhat it means for PTs
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What it does not show
The study included only 13 participants, which limits the generalizability of the findings. The torque timing and magnitude were fixed for all participants, which may have interfered with some natural movement patterns and prevented individualized optimization. The study measured immediate biomechanical changes in a laboratory setting, not the long-term clinical impact on freezing episodes or fall rates. One author is a co-inventor of the device being tested, which introduces potential bias.
Declared interests
Elizabeth Hsiao-Wecksler is a co-inventor of a US patent for the portable powered ankle-foot orthosis (PPAFO) device used in the study. The patent has not been licensed to any company.
The easy way to misread this
Do not assume this device reduces actual freezing episodes or fall risk in daily life. The study measured biomechanical adjustments during gait initiation in a laboratory, not clinical outcomes like the frequency of freezing or falls.