The effects of prosthetic ankle stiffness on ankle and knee kinematics, prosthetic limb loading, and net metabolic cost of trans-tibial amputee gait

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.…”

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

“…Previous research on systematic variations in prosthesis stiffness has suggested that low dorsiflexion stiffness facilitates kinematics more similar to the gait of nondisbled people without amputation and that reductions in foot stiffness encourage gait adaptations reflective of an enhanced ability to control upright posture [36][37]. Additionally, the gait of individuals with bilateral transtibial amputation displays a reduction in step width with increased prosthetic ankle range of motion, suggesting improved balance confidence [13,38].…”

“…The custom foot-ankle mechanism (CFAM) designed and fabricated for this study (Figure 1) allowed independent modulation of the plantar flexion and dorsiflexion rotational stiffnesses of a single-axis ankle joint (i.e., the change in resisting torque per unit angular rotation) without simultaneously changing other mechanical properties or requiring modification of prosthesis alignment. The design and characterization of the CFAM is described in detail by Major et al [36,42]. Importantly, the CFAM was designed to be used without shoes to reduce the confounding influence of different shoe material properties and maintain complete control of the prosthesis properties, but treading was attached to the plantar surface to increase friction between the prosthesis and the ground (i.e., treadmill).…”

“…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].…”

“…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]. We also hypothesized that low dorsiflexion stiffness that facilitates walking kinematics more similar to the gait of nondisabled people without amputation, particularly tibial progression, would improve gait stability [32,[34][35][36].…”