Todd Kuiken, MD, PhD, the director of the Neural Engineering Center for Bionic Medicine at the Rehabilitation Institute of Chicago (RIC), is the man behind the mind power. After more than 20 years of research, Kuiken’s once outlandish endeavor has the ability to profoundly influence the lifestyles of amputees. With a team of experts, Kuiken has advanced and maximized the potential of his efforts to create the six-motor prosthetic arm. Patients Jesse Sullivan and Claudia Mitchell who have been fitted with this technology prove its success.
How it works
To implement the RIC’s Bionic Arm technology, the nerves that once existed in the amputated arm are transferred to the muscles in the chest through the reinnervation process, explained Laura Miller, PhD, CP, the lead prosthetist on Kuiken’s team at the RIC.
The rerouted nerves send signals directly to the chest using standard surface electrodes. When Sullivan or Mitchell think about closing their hand, for example, the thought is sent to the nerve in the chest where the reinnervation has taken place, which then fires the muscle resulting in the hand closing.
“I appreciate this technique because it does not require any implantations,” Miller said. “There is no hardware [implanted] that might fail and need to be replaced someday.”
The process is compatible with devices that are commercially available, which would allow more patients to take advantage of the technology, although an initial amputation could only have occurred within one year for the individual to be a candidate for the procedure. Also, additional research prostheses have been developed which Sullivan and Mitchell have had the chance to use. These are not yet available for everyday use although Miller said that it is a goal of the RIC once the components’ quality and durability have been improved.
The six-motor arm, RIC’s latest addition to the Bionic Arm technology has been in use since 2005. It allows for greater function and multiple movements simultaneously.
“Typically someone with a shoulder disarticulation level of amputation is only fit with three motors because trying to control anymore than that with just a few inputs is hard,” Miller told O&P Business News.
Bionic Arm technology is not about being typical, as the first male and female Bionic Arm recipients would prove.
Jesse Sullivan, a high-power lineman, was electrocuted in May 2001. The electric shock was so great that both of his arms needed to be amputated, leaving him to wonder about how this change would influence his life and whether he would be able to hug his grandchildren.
Sullivan is the first person to undergo the nerve transfer procedure.
Sullivan was refit with his conventional prostheses about 6 weeks after the procedure was complete. After about 6 months, after the nerves completely reinnervated, the RIC team started to take advantage of new signals in his chest and see the value of all of their hard work. Sullivan quickly adapted to using his prostheses and surprised the RIC team when he discovered he could sense touch with his prostheses. Miller explained the discovery that took place during one of the projects Sullivan was involved with when the team used self-adhesive electrodes.
“I was cleaning the skin with alcohol and he said it felt cold in his hand,” Miller said.
Sullivan had also previously explained that sometimes while laying on the couch on his side, it felt like he was lying on his arm. Since the procedure, Miller said Sullivan does not let anything slow him down and she has the stories to back up her claim.
“The forearm is splattered with paint from painting the garage and flower boxes,” she said. “He also sheared the screws that connect the shoulder to the socket trying to pull start the lawnmower.”
While the team did not initially plan to give Sullivan the power to sense touch, it was already in the plan for the first female who would undergo the process.
Claudia Mitchell, a former U.S. Marine Corps officer, lost her left arm in 2004 when it was severed in a motorcycle accident. After reading about Sullivan, Mitchell did her own research and spoke with Kuiken who found her to be a strong candidate for the procedure.
Mitchell underwent nerve transfer in 2005. Mitchell’s procedure was much like Sullivan’s except that physicians planned a way to give her more sensory feedback.
“They found the nerves that go to the skin to innervate the skin, cut those nerves so the skin would be numb and connected the sensory nerves that were from the arm to the skin nerves,” Miller said. “[Mitchell] definitely has sensation of her arm and hand in the skin of her chest.”
Future of the technology
Developments in other areas of prosthetics could allow for further implementation of the Bionic Arm technology. The recently unveiled powered prosthetic leg is just one area with which Kuiken’s team is hopeful of collaborating.
Miller notes that lower limb amputee implementation is still in brainstorming stages.
Right now research is underway to determine how the Bionic Arm technology is impacting patients in the areas of sensory feedback and brain mapping.
Better sensory feedback would give amputees additional information about reacting to and manipulating the environment around them. Through the use of conventional prostheses, the user must watch the objects they are holding to see the firmness of their grip.
“This could give the person feedback about how hard they are holding things without having to see,” Miller said.
They will be able to feel, for example, if they are crushing a paper cup in their hand, she explained.
Given the success of both of these surgeries, the team and the RIC want to explore ways to perfect current surgical techniques.
To date, six people have had the procedure with only one unsuccessful outcome due to an unforeseen nerve injury.
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Jennifer Hoydicz is a staff writer for O&P Business News.