Feasibility of using acceleration-derived jerk to quantify bimanual arm use.
Ying-Chun Preston Pan, Brianna Goodwin, Emily Sabelhaus and 5 others
PMID 32178695WHAT IT FOUND
A jerk ratio from wrist accelerometers tracked relative arm use in children with cerebral palsy while the dominant arm was cast and occupational therapy was given, and matched existing activity-count measures.
It is a possible open-source monitoring tool, not proof that this treatment improves function.
Key findings
01JR50 was 0.578 ± 0.041 before therapy, 0.378 ± 0.125 during therapy, and 0.591 ± 0.057 after therapy in children with cerebral palsy.
02JR correlated with use ratio and magnitude ratio in the cerebral palsy group with r = -0.92 and 0.89, and in the typically developing group with r = -0.76 and 0.74.
03An acceleration ratio derived from raw acceleration did not differentiate the cerebral palsy and typically developing groups and did not demonstrate changes during therapy.
STILL TO COME
How it was doneWhat they foundWhat it means for OTs
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What it does not show
The sample was very small, and the analysis used previously collected data after exclusions. Short monitoring periods may not capture usual day-to-day variation in activity. Jerk ratio cannot distinguish rotational from linear movement because no gyroscope was used. The method was not tested in adult stroke survivors or amputees. Jerk ratio returned to baseline after therapy, so it does not show lasting change. No clinical thresholds or treatment decision rules were developed.
Declared interests
Seattle Children’s Hospital and the National Institute of Biomedical Imaging and Bioengineering funded the work. No author conflicts of interest are reported in the supplied text.
The easy way to misread this
Do not read this as evidence that casting plus occupational therapy improves lasting arm function. It was a small feasibility analysis of a measurement method, and jerk ratio returned to baseline after therapy.