Angulation vs translation of transtibial prosthetic socket: their difference analyzed by socket reaction moments

Previous studies investigated the effects of alignment changes in transtibial prostheses on socket reaction moments. However, the effects of angular and translational alignment changes with equal displacement between the foot and the socket were not directly compared.

What are the different effects of angular and translational alignment changes in transtibial prostheses?

Ten individuals with transtibial prostheses participated in the measurement of temporo-spatial parameters, socket reaction moments, and their timings under nine alignment conditions (3° flexion/extension, anterior/posterior translation, 6° adduction/abduction, medial/lateral translation, and baseline). The displacement of the prosthetic feet was set to be equal between the angular and translational changes.

No significant changes in walking speed were found. Similar effects were observed in the magnitudes, but not in timing, of the moments under angular and translational changes in the sagittal plane (p < 0.01 for the differences in peak extension moment among anterior translation, baseline, and extension conditions, and in peak flexion moment among anterior translation, baseline, and extension conditions). In the coronal plane, similar effects were found in the magnitudes of the moments in the early stance (p < 0.01 at 5 %, 20 %, and 75 % stance). A significant difference in magnitude was observed in the late stance (p < 0.01 between adduction and medial translation conditions).

The timing of the socket reaction moment may be different in the sagittal plane, while the magnitudes of the socket reaction moment in the late stance may be different in the coronal plane between the angular and translational alignment changes.