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

Abstract

Abstract-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.

Considering passive mechanical properties and patient user motor performance in lower limb prosthesis design optimization to enhance rehabilitation outcomes

“…This approach is limited as outcomes are only attributable to arbitrary device classifications, which historically resulted from subjective evaluations on topology, modular components, and material composition. Without knowledge of the device’s user-independent mechanical properties, it is impossible to establish relationships between objective device characteristics and user outcomes 41 . Although there are notable exceptions when commercial prostheses characterization is included to correlate mechanical function with user outcomes 42–44 , these studies are constrained within the range of prosthesis properties available through commercial devices.…”

“…These parametric studies can be separated into: human subject in-vivo testing that employ experimental prostheses 34, 47–57 (Figure 2), and numerical in-silico simulations incorporating physics-based prosthesis models 58–64 (Figure 3). To facilitate in-vivo testing, standardized methods for reliably characterizing the mechanical properties of commercial and experimental prostheses, including combinations of stiffness, damping, and roll-over geometry, have been developed 41, 65–67 . There are benefits and limitations to both types of studies.…”

The effects of prosthetic ankle stiffness on stability of gait in people with transtibial amputation

“…Irrespective of alignment, these results suggest that prosthesis stiffness could be a direct modifiable factor to be considered for prescription guidelines to influence a user's perceived stability and fall risk. The common standard of practice in rehabilitation for people with amputation is to optimally match patients with prosthetic components to maximize mobility outcomes, so the outcomes from this study provide valuable insight into our understanding of prostheses effects on user performance [40]. The prescription process will be further enhanced as techniques are improved for classifying patients based on their rehabilitation potential and mobility and classifying prostheses based on their amputee-independent mechanical properties [41,[54][55][56].…”

“…Walking on slopes and at a fast speed was included to more closely reflect the reality of community walking and enable generalization of the results beyond level walking at self-selected speed [39]. The use of an experimental prosthesis with adjustable mechanical properties is a novel and convenient method for performing in vivo studies that aim to establish the effect of isolated properties on user performance, thereby aiding understanding of the fundamental relationship between prosthesis mechanical function and prosthetic gait quality [36,40]. We hypothesized that low plantar flexion stiffness would reduce the time to foot-flat [32][33]35], and that time to foot-flat would be inversely related to perceived stability [10,13,22].…”

Interrater reliability of mechanical tests for functional classification of transtibial prosthesis components distal to the socket

“…Recent investigations have begun to explore and define the fundamental relationships between user performance (e.g., metabolic cost, joint dynamics, and residuum forces) and isolated mechanical properties (i.e., stiffness and damping) of passive prostheses, measured through mechanical characterization tests independent of the user [4][5][6][7]. Summarily, the results from these studies strongly suggest that the mechanical function of prostheses has an important role in the health and mobility of the user.…”