Natural Sensation of Foot-Floor Interactions for Transfemoral Amputees via Neural Stimulation
Abstract
Despite noteworthy advances in robotic prostheses for lower limb amputees, natural sensory feedback from the lost limb has not yet been incorporated into current prosthetic technologies. To compensate for the lack of sensation, amputees increase the loads applied to their intact limbs during standing and walking, putting them at risk for long-term damage from overuse. Amputees are also extremely slow to adapt to loss of lower limb sensation, and fall-related fear and anxiety are all lifelong consequences of amputation. Except for the mechanical loads transferred to the residuum, or conscious visual attention, no lower prosthesis for trans-femoral amputees offers a permanent and reliable method to restore a natural sense of the status of the missing joints, limb segments, and interactions with the ground or surrounding environment. These issues are particularly important for trans-femoral amputees, who constitute approximately 40% of the entire amputee population. Unlike trans-tibial amputees, the sensate areas of the residuum are far removed from the ground and information is missing from the knee as well as the ankle, making indirect perception of foot-floor contact and limb position even more indirect. Although there have been numerous attempts to provide such feedback by substituting vibrations on other areas of the skin unassociated with leg-ground interactions, nothing to date has successfully restored truly natural sensation that is perceived immediately and directly as coming from the missing limb. The objective of this 4-year project is to provide useful and natural sensation of prosthetic foot-floor interactions to trans-femoral amputees by directly interfacing with the nervous system. Exciting the peripheral sensory nerves that remain intact after amputation will activate existing areas in the brain associated with plantar pressure or skin contact in the missing limb, thus making the evoked sensations seem natural and as if they arise from the phantom limb. The quality, location, modality, and intensity of electrically elicited sensation will be quantified, as well as its effects on standing balance, gait mechanics and symmetry, and the user’s ability to negotiate unstructured terrain and uneven surfaces. Positive effects on the cognitive burden of walking in unfamiliar or distracted environments incidence and fear of falling, body image, balance confidence, and frequency and severity of phantom pain are anticipated. Five individuals with trans-femoral limb loss will each have two new 16-contact Composite-Flat Interface Electrodes (C-FINEs) implanted on the femoral nerves in the upper back of the thigh of their residual limb. Each of the 32 contacts will be connected to temporary lead wires that exit the skin. After fully characterizing the stimulus-evoked sensation, subjects will be fit with an advanced microprocessor-controlled knee with a rich set of embedded sensors that monitor limb loading, knee angle, and other important information about how the prosthetic leg interacts with the environment. Data from the sensors will be mapped to stimulation to the appropriate contact to generate the corresponding sensation, which is perceived as originating from the missing limb. After determining the relative benefits of sensory stimulation on posture, balance, walking, climbing, and negotiating ramps or obstacles in the laboratory, users will be given the sensory-enabled systems for unsupervised use in the home and community. More than 90% of amputations in the United States and recent estimates indicate that the number resulting from battlefield trauma has been increasing significantly. No existing lower limb prosthetic device is truly integrated with the intact nervous system to provide the real-time feedback of the sensory information that is vital to maintaining balance, avoiding obstacles, preventing falls, or negotiating unfamiliar environments without visual input or conscious attention. Res
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Oct 29, 2018
- Source ID
- W81XWH1810321
Entities
People
- Ronald J Triolo
Organizations
- Case Western Reserve University
- United States Army