Sagittal and transverse ankle angle coupling can influence prosthetic socket transverse plane moments.
Glenn K Klute, Connor W Mulcahy
PMID 38638287WHAT IT FOUND
A motorized prosthesis coupling sagittal and transverse motion showed a 6:1 ratio trended toward lower socket torque during straight and outside-circle walking, but results were inconsistent and no other gait metrics changed.
Key findings
01The 6:1 coupling ratio showed statistically lower peak transverse plane moments compared to 3:1 and 2:1 ratios during straight and outside-circle walking.
02No significant differences were found across coupling ratios for hip, knee, or ankle power, kinematics, or ground reaction forces.
03Participants reported similar satisfaction scores across all coupling ratios, with many unable to distinguish differences between conditions.
STILL TO COME
How it was doneWhat they foundWhat it means for PTsWhat it means for OTsWhat it means for SLPs
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What it does not show
Small sample size (n=11) limits statistical power and generalizability. The TAP device was approximately three times heavier than a conventional prosthetic foot, which may have influenced gait speed and satisfaction. Acclimation time was short (15 minutes), which may not reflect long-term use. Turning speeds were slower than previously reported, which may have reduced the magnitude of transverse plane moments. Only five specific coupling ratios were tested; the optimal ratio may lie between these points.
Declared interests
The study was supported by the United States Department of Veterans Affairs Rehabilitation Research & Development Service and the VA Technology Transfer Office (BRAVE).
The easy way to misread this
Do not assume the 6:1 ratio is clinically superior for all amputees. The effect was only significant for specific walking directions compared to specific ratios, and the heavy prototype device may have altered natural gait mechanics.