Stance phase mechanical characterization of transtibial prostheses distal to the socket: a review

Achieving the required functionality of a transtibial prosthesis during the stance phase of gait (e.g., shock absorption, close to normal roll-over characteristics, and smooth transition into swing) depends on the Amputee Independent Prosthesis Properties (AIPPs), defined here as the mechanical properties of the prosthesis that directly influence the performance of the amputee. Accordingly, if research studies are to advance the design of prostheses to achieve improved user performance, AIPPs must be a primary consideration. However, the majority of reported studies can be categorized as either human performance testing of commercial prosthetic components or AIPP characterization; only in a few notable cases have studies combined these two approaches. Moreover, very little consistency exists in the current methods used for AIPP characterization, thus making comparisons between the results of such studies very difficult. This article introduces a framework for studying prosthesis design, which includes AIPP characterization, human performance and/or gait simulation studies, and detailed design. This framework provides a structure for reviewing previous approaches to AIPP characterization, discussing both their merits and shortcomings and their use in previous experimental and simulation studies. For the purposes of this review, stance phase AIPP models have been categorized as either lumped parameter or roll-over shape based.