A Prototype of a Neural, Powered, Transtibial Prosthesis for the Cat: Benchtop Characterization.

Hangue Park,Alexander N Klishko,Muhammad S Islam,Boris I Prilutsky,Martha A Grover,Stephen P Deweerth

doi:10.3389/fnins.2018.00471

Hangue Park, Alexander N Klishko + Show 4 more

Open Access

https://doi.org/10.3389/fnins.2018.00471

Copy DOI

Abstract

We developed a prototype of a neural, powered, transtibial prosthesis for the use in a feline model of prosthetic gait. The prosthesis was designed for attachment to a percutaneous porous titanium implant integrated with bone, skin, and residual nerves and muscles. In the benchtop testing, the prosthesis was fixed in a testing rig and subjected to rhythmic vertical displacements and interactions with the ground at a cadence corresponding to cat walking. Several prosthesis functions were evaluated. They included sensing ground contact, control of transitions between the finite states of prosthesis loading, and a closed-loop modulation of the linear actuator gain in each loading cycle. The prosthetic design parameters (prosthesis length = 55 mm, mass = 63 g, peak extension moment = 1 Nm) corresponded closely to those of the cat foot-ankle with distal shank and the peak ankle extension moment during level walking. The linear actuator operated the prosthetic ankle joint using inputs emulating myoelectric activity of residual muscles. The linear actuator gain was modulated in each cycle to minimize the difference between the peak of ground reaction forces (GRF) recorded by a ground force sensor and a target force value. The benchtop test results demonstrated a close agreement between the GRF peaks and patterns produced by the prosthesis and by cats during level walking.

Highlights

Individuals with lower limb loss wearing a unilateral passive prosthesis frequently show asymmetric walking, which can lead to undesirable compensations and subsequent degenerative musculoskeletal conditions (Burke et al, 1978; Jaegers et al, 1995; Struyf et al, 2009)
The stimulator was tested in walking cats – electrical stimulation was applied to the distal tibial nerve during the stance phase of walking and reduced or reversed effects of paw pad anesthesia on the duty factor and step length symmetry (Park et al, 2015, 2016)
The size, mass, and maximum extension moment of the prosthesis closely matched the corresponding parameters of the cat foot-ankle with the distal shank and the peak ankle extension moment produced during level walking in the cat (Gregor et al, 2006, 2018; Prilutsky et al, 2011)

Summary

Introduction

Individuals with lower limb loss wearing a unilateral passive prosthesis frequently show asymmetric walking, which can lead to undesirable compensations and subsequent degenerative musculoskeletal conditions (Burke et al, 1978; Jaegers et al, 1995; Struyf et al, 2009). Among the variety of underlying reasons causing locomotor asymmetry, the inappropriate motor output and the lack of somatosensory feedback from the prosthetic limb are probably most important (Hof et al, 2007; Kannape and Herr, 2014). To correct these motor and sensory deficits, it is necessary to establish a bidirectional communication interface between the nervous system and the prosthesis. It might be possible to improve locomotor outcome measures (e.g., walking symmetry) by controlling a powered prosthesis or orthosis using myoelectric signals from residual or intact muscles (Sawicki and Ferris, 2009; Herr and Grabowski, 2012; Takahashi et al, 2015; Kannape and Herr, 2016)

Objectives

Methods

Results

Discussion

Conclusion