In a study published in the Journal of Rehabilitation Research & Development, researchers found that with training, subjects with a transtibial amputation were able to improve the volitional control of their residual-limb muscles. This has implications for the development of improved control interfaces for powered lower-limb prostheses.
For this study, a team of researchers from the Human Neuromechanics Laboratory and School of Kinesiology, University of Michigan, Ann Arbor; the Rehabilitation Research and Development Center of Excellence for Limb Loss Prevention and Prosthetic Engineering, Department of Veterans Affairs Puget Sound Health Care System, Seattle, Washington; and the Department of Rehabilitation Medicine, University of Washington, Seattle, assessed motor learning in people with transtibial amputations and whether years since amputation correlated with performance. The study analyzed proportional myoelectric control from the tibialis anterior muscle by having the participants perform tracking tasks of a virtual object, using electromyography (EMG) to evaluate the activity produced by the tibialis anterior.
Nine unilateral transtibial amputees (seven men and two women with an average age of 50) and 13 able-bodied people (ten men and three women, with an average age of 25) participated. Seven of the subjects had amputations about five years ago and two had amputation more than 15 years ago. The participants performed 20 trials over one hour, with breaks between each trial. Even though subjects with a transtibial amputation initially performed much worse than able-bodied subjects, after a short training period all participants had similar error rates, and for those with an amputation, the time since amputation ceased being a factor. The researchers conclude that this provides evidence for the future use of proportional myoelectric control of powered lower-limb prostheses.