Performance of the CYBERLEGs motorized lower limb prosthetic device during simulated daily activities

Abstract

Background The CYBERLEGs-gamma (CLs-ɣ) prosthesis has been developed to investigate the possibilities of powerful active prosthetics in restoring human gait capabilities after lower limb amputation. Objective The objective of this study was to determine the performance of the CLs-ɣ prosthesis during simulated daily activities. Methods Eight participants with a transfemoral amputation (age: 55 ± 15 years, K-level 3, registered under: NCT03376919) performed a familiarization session, an experimental session with their current prosthesis, three training sessions with the CLs-ɣ prosthesis and another experimental session with the CLs-ɣ prosthesis. Participants completed a stair-climbing-test, a timed-up-and-go-test, a sit-to stand-test, a 2-min dual-task and a 6-min treadmill walk test. Results Comparisons between the two experimental sessions showed that stride length significantly increased during walking with the CLs-ɣ prosthesis (p = .012) due to a greater step length of the amputated leg (p = .035). Although a training period with the prototype was included, preferred walking speed was significantly slower (p = .018), the metabolic cost of transport was significantly higher (p = .028) and reaction times significantly worsened (p = .012) when walking with the CLs-ɣ compared to the current prosthesis. Conclusions It can be stated that a higher physical and cognitive effort were required when wearing the CLs-ɣ prosthesis. Positive outcomes were observed regarding stride length and stair ambulation. Future prosthetics development should minimize the weight of the device and integrate customized control systems. A recommendation for future research is to include several shorter training periods or a prolonged adaptation period.

The effects of swing assistance in a microprocessor-controlled transfemoral prosthesis on walking at varying speeds and grades

“…Specifically, knee movement can be supplemented with active power, particularly during slow and upslope walking, to increase toe clearance during these activities, and to help ensure full knee extension at the termination of swing phase. Several researchers have developed powered knee prostheses, which employ some type of swing-phase controller to provide swing-phase motion (e.g., Lawson et al, 2014; Azocar et al, 2018; Lenzi et al, 2018; Elery et al, 2020; Ghillebert et al, 2021). Although such approaches increase the robustness of swing phase, powered devices generally entail a higher output impedance relative to passive devices (due to reflected friction and inertia across the transmissions), and this higher output impedance generally sacrifices the ability to provide the (unpowered) ballistic swing phase that is characteristic of level-ground and shallow-slope walking.…”