Altering the tuning parameter settings of a commercial powered prosthetic foot to increase power during push-off may not reduce collisional work in the intact limb during gait.

BACKGROUND: Increased knee osteoarthritis risk in patients with unilateral lower extremity limb loss is attributed to increased intact limb loading. Modulating powered ankle prosthesis push-off power may be an effective way to modulate intact limb loading. We examined how changes in the parameter settings of a commercial prosthetic ankle affect power delivery during push-off and the resulting collisional work experienced by the intact limb in persons with unilateral lower extremity limb loss.

METHODS: Five subjects with unilateral transtibial amputation were fitted with a commercially available powered ankle prosthesis (Ottobock Empower). Subjects walked on a treadmill in seven conditions, where ankle power delivery settings were adjusted using methods accessible to clinicians. Kinetics and kinematics data were collected.

RESULTS: Standard adjustment of parameter settings within the prosthetic foot did not alter timing of peak prosthesis power or intact limb collisional work but did have a significant effect on the magnitude of positive prosthesis ankle work. Increased prosthesis work did not decrease intact limb collisional work as predicted.

CONCLUSIONS: Altering the parameter settings on a commercial powered ankle prosthesis affected the magnitude, but not the timing, of power delivered. Increased prosthesis push-off power did not decrease intact limb loading.