Noting that transtibial prosthesis users have a higher energetic cost of walking than people without amputations and prostheses that restore ankle power do not necessarily decrease the cost, authors of a new study concluded that stabilizing walking may explain the higher energetic consumption.
The researchers assessed the metabolic cost of stabilizing walking against treadmill belt speed perturbations in 16 subjects with unilateral transtibial amputations and 23 subjects without amputations at three walking speeds between 0.6 and 1.6 m/s. The data collected focused on sagittal plane stability, as a transtibial amputation disables muscle-driven modulation of the ankle torque, which plays an important role in controlling walking in the sagittal plane at slow speeds.
The results indicated that perturbations induced 0.24 W/kg larger increases in energy consumption across walking speeds in the subjects with an amputation than in those without. Mean reductions in step length in response to perturbations were similar between groups, but the participants with amputations increased the step-length variability of their intact leg more than participants without amputations, especially at low speeds, according to the study’s authors.
The open-access study, “Transtibial amputation increases the metabolic energy needed for stabilizing walking in the sagittal plane,” was published in the Journal of Applied Physiology.
