Upper limb movement yields rich streams of sensory information that are cortically integrated with motor commands. This is drastically altered in those with upper limb (UL) amputation as sensations of touch and movement are inherently lost. This absence impedes prosthetic control by forcing reliance on visual cues and other indirect means to effectively operate one’s prosthesis. This increases the cognitive burden placed on the user as the prosthesis requires continual attention. While advanced prostheses have been developed, 23-39% of users still reject their devices. A major factor is the absence of physiologically relevant sensation. A unique approach to address this challenge is targeted reinnervation (TR) surgery, which reroutes residual nerves that once serviced a patient’s amputated hand to strategic muscles in the residual limb (RL). This restores sensation in the missing limb and aids in intuitive control of prostheses. While the return of cutaneous sensations has been reported, an equally vital component to limb control, movement (kinesthetic) sensibility, has yet to be investigated.

In this thesis, we highlight an approach for providing kinesthetic sensory feedback communicated to prosthetic users through the existing sensory channels once present in their missing limb. Our approach leveraged the reinnervated anatomy of participants who had previously undergone TR surgery, and the kinesthetic illusion. The latter is a phenomenon whereby vibration of musculotendinous regions of a limb induces sensations of limb movement. Through able-bodied trials, we developed an applied understanding of the kinesthetic illusion in preparation for translation into an amputee population. In a group of participants who have undergone transhumeral amputation and TR surgery, we demonstrated that we could purposefully elicit sensations of missing hand movement and link these sensations to the movement of commercially available prosthetic components. Integrating these techniques into functional prostheses required the development of novel prosthetic sockets allowing vibration stimulators access to the RL, while maintaining socket fit, security and suspension. The engineering challenges of this task necessitated the development of foundational information that is largely absent, such as understanding the socket interfaces mechanics of transhumeral prostheses. A novel socket design was fabricated to incorporate our feedback system, and the RL-socket contact pressures were evaluated. Through comparison to the traditional socket data, it was determined that the novel socket not only successfully integrated a kinesthetic feedback system, but allowed investigators to target specific anatomical locations on the RL for the application of contact pressures. Lastly, a numerical predictive model was developed as a foundation for a future clinical socket design tool. Through the application of finite element analysis, we demonstrated a proof-of-concept model that is capable of predicting the locations and magnitudes of contact pressures occurring between the RL and socket. Applications of this model may allow for the evaluation of novel sensory-integrated prosthetic socket prior to their physical fabrication.

Taken together, this work addresses very real, practical challenges associated with UL prosthetic use. It provides foundational information for the advancement of sensory-motor integrated prosthesis and holds the potential to help restore sensation, and improve prosthetic function.