Enhancing functional abilities and cognitive integration of the lower limb prosthesis

Abstract

Lower limb amputation (LLA) destroys the sensory communication between the brain and the external world during standing and walking. Current prostheses do not restore sensory feedback to amputees, who, relying on very limited haptic information from the stump-socket interaction, are forced to deal with serious issues: the risk of falls, decreased mobility, prosthesis being perceived as an external object (low embodiment), and increased cognitive burden. Poor mobility is one of the causes of eventual device abandonment. Restoring sensory feedback from the missing leg of above-knee (transfemoral) amputees and integrating the sensory feedback into the sensorimotor loop would markedly improve the life of patients. In this study, we developed a leg neuroprosthesis, which provided real-time tactile and emulated proprioceptive feedback to three transfemoral amputees through nerve stimulation. The feedback was exploited in active tasks, which proved that our approach promoted improved mobility, fall prevention, and agility. We also showed increased embodiment of the lower limb prosthesis (LLP), through phantom leg displacement perception and questionnaires, and ease of the cognitive effort during a dual-task paradigm, through electroencephalographic recordings. Our results demonstrate that induced sensory feedback can be integrated at supraspinal levels to restore functional abilities of the missing leg. This work paves the way for further investigations about how the brain interprets different artificial feedback strategies and for the development of fully implantable sensory-enhanced leg neuroprostheses, which could drastically ameliorate life quality in people with disability.

Neurocognitive consequences of hand augmentation

“…To assess the cognitive load related to Thumb use, a numerical cognition task was performed twice, on both the first and the last training sessions (40)(41)(42). Participants were asked to perform a cooperation task, building a Jenga tower (described above), while simultaneously presented with a set of low and high pitch auditory tones played from a laptop.…”

Perceptual correlates of successful body-prosthesis interaction in lower limb amputees: psychometric characterization and development of the Prosthesis Embodiment Scale

“…Evidence for amputees, however, is scarce. In case studies on upper 55,56 and lower limb amputees 57 it has been shown that appropriate multimodal sensory or sensorimotor feedback is capable to enhance prosthesis embodiment. Other prosthesis features not requiring advanced technical solutions might also be capable to facilitate embodiment of the device.…”

Biofeedback Systems for Gait Rehabilitation of Individuals with Lower-Limb Amputation: A Systematic Review

“…Only six studies presented detailed characteristics about the prosthetic components (i.e., prosthetic joint, foot, and socket) utilized to evaluate BFB [34,59,[78][79][80][81]. During BFB testing, most of the participants wore their prescribed prosthesis (i.e., passive mechanical or microprocessor- Table 4 depicts the results of the criteria applied to assess the quality of the reviewed articles.…”

“…During BFB testing, most of the participants wore their prescribed prosthesis (i.e., passive mechanical or microprocessor-controlled knee prostheses). In terms of BFB effectiveness and prosthetic components, the results showed that BFB systems were capable of improving the gait performance of individuals with LLA, regardless of the type of prosthetic components (i.e., passive mechanical knee or microprocessor-controlled knee or powered knee prostheses) [35,59,[79][80][81][82]. FSRs (force sensitive resistors) sensors that were attached to the plantar surface of the prosthetic foot were the most frequently used transducer for measuring the targeted gait parameters.…”