New estimation model of the initial lower limb angle to improve angle estimation during the extension phase of standing-up movement.
Fang Jin, Takayuki Nagasaki, Chikamune Wada
PMID 29765177WHAT IT FOUND
A foot-pressure plate estimated seated thigh and lower-leg angles within 2.78 to 5.98 degrees and 4.87 to 6.31 degrees compared with camera-measured movement in seven healthy male volunteers.
Angle feedback could help physical therapists train standing-up, but patients were not tested.
Key findings
01A foot-pressure sensor plate estimated seated thigh and lower-leg angles within 2.78 to 5.98 degrees and 4.87 to 6.31 degrees compared with motion capture.
02Six participants showed no significant difference between estimated initial angles and motion-capture values, while subject 6 showed a significant difference for the lower-leg angle.
03The errors in the initial lower-limb angles decreased after estimation.
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 seven healthy male volunteers, so it does not show how the model performs in older adults or people with disability. Extension-phase angle errors were reported for six participants, not all seven, and appeared in the Discussion rather than the Results section. The foot sensor had force-measurement errors, and one participant's smaller foot meant the sensors did not line up well under the foot. The model used body segment parameters from previous research based on Americans, which may not match the participants. This was a technical validation against motion capture, not a test of patient outcomes or clinical usefulness.
Declared interests
This work was partly supported by JSPS KAKENHI Grant Number JP15K01461. The authors declared no conflict of interest.
The easy way to misread this
Do not read this as a validated clinical tool for patients. It was tested only in seven healthy male volunteers, the extension-phase analysis included six participants, and subject 6 had a significant estimation error linked to foot size and sensor placement.