Energetic consequences of using a prosthesis with adaptive ankle motion during slope walking in persons with a transtibial amputation

Abstract

Background Technological advances in prosthetic design include the use of microprocessors that adapt device performance based on user motion. The Proprio ankle unit prepositions the foot to adjust for walking on slopes and increases foot clearance during swing to minimize gait deviations. Study design Comparative analysis. Objectives To investigate the effect of a prosthesis with adaptive ankle motion on physiological gait performance during slope walking. Methods Six persons with a unilateral transtibial amputation completed treadmill walking tests at three slopes (−5°, 0°, and 5°). The participants were tested wearing a customary device, active Proprio (Pon), and an identical inactivated Proprio (Poff). Results Metabolic energy expenditure, energy cost for walking, and rating of walking difficulty were not statistically different between the Pon and Poff for all tested slopes. However, for slope descent, energy expenditure and energy cost for walking improved significantly by an average of 10%–14% for both the Pon and Poff compared to the customary limb. Rating of walking difficulty also showed an improvement with slope descent for both the Pon and Poff compared to the customary device. An improvement with slope ascent was found for Pon compared to the customary limb only. Conclusions Adaptive ankle motion provided no meaningful physiological benefit during slope walking. The Proprio was, however, less demanding than the customary device for slope descent. Differences in the mechanical properties of the prosthetic feet likely contributed to the changes.

Active dorsiflexing prostheses may reduce trip-related fall risk in people with transtibial amputation

“…In general, the evidence supporting the use of microprocessor-controlled prosthetic feet for improving balance, function, and/or mobility of people with amputation is limited and has only recently begun to appear in the literature (e.g., references [25][26][27][28][29][30]). At present, there are few English-written studies of the ProprioFoot, and those that exist have focused on socket pressures [31], hip and knee kinematics and kinetics [32][33], gait economy [34][35], and related aspects of gait [36][37] but not on MTC. Our study is the first to quantify MTC at different speeds and inclines and to report a reduced likelihood of tripping by people with TTAs.…”

“…However, older adults with faster walking speeds have been shown to fall at greater rates following a laboratory-induced trip because of greater angular momentum [47], and in the community faster walking speed is associated with greater incidence of outdoor falls [48][49] where, compared with indoor falls, tripping is more prevalent [3,50]. Third, in contrast to previous studies with the ProprioFoot, which have compared outcome variables with and without the adaptive features turned on [32][33][34], the current study employed a pseudo-crossover design. Thus, it is possible that differences in MTC may be attributed to differences in foot design that are independent of inertial differences [51][52].…”

Advances Regarding Powered Prosthesis for Transtibial Amputation

“…The Ossur Proprio, capable of adjusting foot orientation angle, has demonstrated partial success for improving metabolic expenditure in light of incline, decline and level ramp walking for transtibial amputees. 35 The PowerFoot BiOM is capable of providing its user with powered plantar flexion, which has demonstrated a notable reduction in metabolic cost. 36 Preliminary design of the powered ankle-foot prosthesis was conducted by Au et al as a research and development prototype through the MIT Department of Mechanical Engineering.…”

“…Also the proper heel strike during stance initiation can be facilitated by a powered dorsiflexion equipped with artificial intelligence to evaluate gait patterns. 35,49 One notable issue with the Proprio Foot by Ossur is the inability to generate powered plantar flexion. During swing phase the Proprio Foot ankle joint eventually locks in position.…”

“…Subjects can be included in a study based on the duration they have not needed an assistive device. 35 Mancinelli et al incorporated the Special Interest Group of Amputee Medicine (SIGAM) at levels E to F as an eligibility requirement to confirm high-level ambulators for their study. 36 The SIGAM scale enables a reliable strategy for evaluating lower limb amputee mobility, while designed with the sensitivity to detect changes in mobility.…”