A comparative study of oxygen consumption for conventional and energy-storing prosthetic feet in transfemoral amputees

Objective: To compare oxygen consumption for traumatic high-functioning transfemoral amputees wearing initially a conventional prosthetic foot (Multiflex) and then an energy-storing prosthetic foot (Vari-Flex).

Setting: A regional prosthetic and amputee rehabilitation tertiary referral centre in a teaching hospital.

Study design: Experimental crossover trial.

Subjects: Six established unilateral transfemoral prosthetic users.

Interventions: Oxygen consumption breath-by-breath analysis at multiple speeds on a treadmill for each amputee wearing initially the Multiflex foot and then repeated wearing the Vari-Flex foot.

Results: Mean oxygen consumption across all subjects was lower for the Vari-Flex foot than for the Multiflex foot at all speeds, although the differences were only significant at speeds of 0.83 and 1.1 m/s (P < 0.05). ANCOVA analysis across all speeds showed that oxygen consumption with the Vari-Flex foot was significantly lower (P < 0.001). The estimated difference across all speeds was 3.54 mL/kg.min.

Conclusion: A high functioning transfemoral amputee who wears an energy-storing prosthetic foot may have significantly reduced oxygen consumption at normal walking speeds.