Evaluation of a powered ankle-foot prosthetic system during walking.

OBJECTIVE

To determine whether a powered ankle-foot prosthesis improves gait mechanics, physical performance, and user satisfaction after traumatic transtibial amputation.

DESIGN

Pre-post.

SETTING

Gait analysis laboratory.

PARTICIPANTS

Young individuals with traumatic transtibial amputation (n=11) and matched controls (n=11).

INTERVENTIONS

Wearing an energy-storing and -returning (ESR) foot and a powered ankle-foot prosthesis.

MAIN OUTCOME MEASURES

Gait mechanics, physical performance, and user satisfaction.

RESULTS

The powered prosthesis ankle range of motion (ROM) was significantly larger (∼30%) than that of the ESR limb. However, both devices demonstrated significantly less ankle ROM than the control and intact limbs. At preswing, the ESR limb generated approximately 40% less peak ankle power than control and intact limbs. In contrast, the powered prosthesis generated significantly greater peak ankle power than control (35%) and ESR (∼125%) limbs, resulting in the powered limb absorbing twice the peak knee power observed in the control and intact limbs. The powered prosthesis limb peak hip power generation was approximately 45% greater at preswing than that of the intact limb. Walking velocity increased with the powered prosthesis compared with the ESR limb and was greater than that of the control group. However, physical performance measures were not significantly different between ESR and powered conditions. User satisfaction scores indicated a preference for the powered prosthesis over the ESR limb.

CONCLUSIONS

Compensatory strategies during gait with the ESR and powered prosthetic devices were similar to those reported in the literature. However, the addition of ankle power and ROM by the powered prosthesis appeared to increase compensatory strategies at proximal joints.