Pressure based MRI-compatible muscle fascicle length and joint angle estimation.
Hyungeun Song, Erica Israel, Shriya Srinivasan and 1 others
PMID 32843093WHAT IT FOUND
A pressure sensor over the tibialis anterior estimated ankle angle and muscle length within 5 to 6% of the tested range in five subjects during dorsiflexion.
Using a reference sensor improved accuracy through full ankle motion. It is not a treatment result.
Key findings
01During dorsiflexion trials, pMMS estimated joint angle with 4.8 ± 0.5% error and fascicle length with 5.7 ± 1.8% error across five subjects.
02During full dorsiflexion and plantar flexion, pMMS joint-angle error was 13.9 ± 1.7% and fascicle-length error was 11.9 ± 2.0%.
03The differential-pMMS setup improved full-range joint-angle error to 7.0 ± 2.5% and fascicle-length error to 6.4 ± 1.2%.
STILL TO COME
How it was doneWhat they foundWhat it means for PTs
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What it does not show
Only five subjects were tested, and the study reports sensor accuracy, not patient outcomes or treatment effects. Sensor accuracy depended on placement and sleeve tension, and parameters varied widely between subjects. The pMMS became less accurate during full range motion because surrounding muscles and extreme plantar flexion disturbed pressure readings. The device was not tested during isometric contraction, passive stretching, or weight-bearing tasks, which are common in rehabilitation. MRI compatibility is suggested by the design, but the supplied text does not report a completed fMRI clinical study. The supplied text does not describe randomisation, blinding, or a control group.
Declared interests
The supplied publication types note non-U.S. government research support, but the article text gives no author conflict declaration.
The easy way to misread this
Do not read this as evidence that pressure sensing improves rehabilitation or can replace clinical assessment. The study only tested sensor accuracy in five subjects during ankle movements, and the authors state the device still needs testing during passive stretching and weight-bearing tasks.