The groundbreaking targeted muscle reinnervation (TMR) surgical technique developed by Todd Kuiken, MD, PhD, at the Rehabilitation Institute of Chicago (RIC), Illinois, requires pioneering occupational therapy treatment to enable these amputees to take advantage of their enhanced capabilities.
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| Kathy Stubblefield, OTR/L, watches patient Claudia Mitchell perform a functional task test to record the speed and agility of the neural-controlled prosthesis. Photograph courtesy of the Rehabilitation Institute of Chicago |
Kuikenis director of RIC's Neural Engineering Center for Artificial Limbs (NECAL); leading the NECAL occupational therapy team is Kathy Stubblefield, OTR/L. Stubblefield has worked with all seven RIC amputee patients who have undergone the landmark surgery, including Jesse Sullivan, who lost both arms at the shoulder due to an electrical accident while working as a utility lineman, and Claudia Mitchell, a former marine who lost her left arm at the shoulder in a motorcycle accident. Both Sullivan, then age 59, and Mitchell, then 26, became international media sensations after they underwent TMR surgery and were fitted with "thought-control" prostheses. (Editor's note: For more information on TMR surgery, see " Targeted Muscle Reinnervation: The Future Is Now ." More information on advanced prosthetics research is available at www.oandp.com/edge )
Stubblefield was honored as one of the "25 Most Influential" therapists by Therapy Times in 2006 for her work with amputee patients "who have been fitted with the neural-controlled 'bionic arm' technology pioneered by Dr. Todd Kuiken and his team." Stubblefield has worked with these patients since 2001 on tasks and functional training and testing to ensure they achieve the best possible results, noted Therapy Times .
Stubblefield is highly enthusiastic about TMR surgery. "I think it's a fabulous thing," she says. "Amputees are able to use intuitive, physiologically appropriate effort to move the artificial arm. It's incredible that the nervous system can be manipulated like that."
Exploring the New Frontier
Working with patients who had undergone TMR surgery was a new frontier for occupational therapy. "I didn't know how to approach it at first," Stubblefield says.
"After Jesse Sullivan, [the first to undergo the surgery at RIC], we learned more about what to expect in an outcome. We learned more about the type of program that could help patients during the post-surgical interim period while their muscles were reinnervating and what activities would promote better control."
Just which part of the peripheral nerve will reinnervate the muscles to provide the strongest myoelectric signal is unpredictable; therefore, the occupational therapy program aims to increase strength throughout the relevant motor distribution of the transfer nerve. Stubblefield feels that because RIC patients were all experienced prosthesis users before their TMR surgeries, it was easier for them to adapt to the enhanced number of myoelectric signals. "We did have to get them out of the habit of doing things the way they used to," she says. "The challenge was helping them to take advantage of what they now had. We didn't have to teach them where they need to be-we needed to teach them how to get there, and they learned very quickly."
However, Douglas Smith, MD, professor of orthopedic surgery at the University of Washington, Seattle, also found that his TMR patients learned to use their prostheses faster and easier than those without the surgery. Smith's patients have been traumatic amputees, with all but one having TMR surgery at the time of their initial amputation surgery, thus they were not previous prosthetic users.
During the reinnervation interim period, a home exercise program included phantom exercises that corresponded to the distribution of transferred nerves and the anticipated degrees of freedom in the prosthesis, Stubblefield explains in a paper-in-progress discussing the surgery, occupational therapy training, and prosthetic fitting for three shoulder disarticulation patients. Similar techniques can be used for transhumeral amputees.
The patients' response to the program was then an important guide to the training undertaken with the new prosthesis. "The home program can help the patient and therapist decipher and refine the 'transfer' movements that best interface with the control scheme," Stubblefield notes.
When the therapist, prosthetist, and patient agreed that the socket fit and control was optimal by using drills, training using the new paradigm progressed, Stubblefield says. When the patient and therapist established how the patient would move the prosthetic components, they proceeded to functional activities.
Since prosthesis wearers rarely use the artificial arm as their dominant, or preferred, extremity, training included one-handed activities, such as unloading a dishwasher, using only the prosthesis. "Forced use may encourage the patient to explore the increased potential for efficiency using the new control paradigm," Stubblefield says.
Since the amputees had been using the sequential movements of conventional prostheses, the therapist cued the patient to "pick up the pace" to foster movement of two degrees of freedom simultaneously. Repetitive tasks requiring the use of the hand and elbow were repeatedly performed with increasing speed. The patients quickly learned the advantages of not having to switch between functions, improving speed and ease of movement.
Finally, bimanual tasks were given, forcing the patient to slow down again and find the most efficient, effective way to integrate the prosthesis. "The hope is that forced-use problem solving enhances the bimanual task performance," Stubblefield says.
Successful Results
"The advantage of additional myoelectric sites in controlling a myoelectric prosthesis at this high level of amputation is apparent when the speed of task performance is examined and patient perspectives are considered," Stubblefield said in a presentation to the 2005 American Occupational Therapy Association (AOTA) Annual Conference. "When viewing video of the training and testing sessions, the difference is evident... These three individuals report subjectively that the greatest improvement is the ease of moving freely. The outcomes clearly demonstrate that successful TMR results in easier, more efficient prosthetic control impacting the functionality of these devices in the everyday lives of their users."
Miki Fairley is a freelance contributing editor and writer for The O&P EDGE based in southwest Colorado. She can be contacted via e-mail at miki.fairley@gmail.com
