A biomechanistĝ€™s perspective on partial foot prostheses

A systematic review of the biomechanics of walking after partial foot amputation was recently performed by Dillon and colleagues. Their review illustrated a high level of evidence from the literature that human gait is altered by partial foot amputation but low to insufficient evidence to demonstrate the effects of various types of prosthetic and orthotic devices on gait of persons with partial foot amputation. More work is needed to understand the biomechanical effects of various partial foot prosthetic devices on level and nonlevel walking surfaces. With this knowledge, medical personnel could more easily ascertain the safest and most functional device for a person with a partial foot amputation.There appear to be parallel findings in rehabilitation research literature that may lend insight into the evaluation and design of partial foot prostheses. This article describes past efforts of various investigators in understanding the role of the ankle plantarflexors in walking, the function of various prosthetic feet for transtibial prosthesis users, the use of rockers to describe walking characteristics, and the use of rockers in walking toys and machines. The article then describes the roll-over shape concept, how it has been used to study able-bodied persons walking on level and ramp surfaces, and how it has been used to examine the effects of prosthetic feet on gait characteristics. Finally, this articles addresses the potential usefulness of the roll-over shape for determining relative biomimesis (i.e., the degree to which the person-machine system mimics the intact physiologic system) of various partial foot prosthetic systems. These measurements coupled with other outcome measures could be useful in the future design and prescription of these devices.