Phantom limb pain is a common problem for people who undergo amputation, and so is the ability to function even with a regular prosthetic, but a medical advance that sounds like it comes straight out of 鈥淪tar Wars鈥� is giving at least one woman significant relief from that pain. She now has a functioning bionic prosthetic hand that can feel some sensations and help her do about 80 per cent of what she used to do with both hands.
While Luke Skywalker鈥檚 human-like bionic hand is still years away, scientists say they are a step closer with this newest prosthetic technique, and doctors hope others will soon benefit from this approach.
Karin, whose full name is not disclosed in the proof of concept study published Wednesday in the medical journal Science Robot, had been using a regular prosthetic hand for years, but it was hard to control. And as with even the most technologically advanced prosthetics on the market, it was uncomfortable and sometimes even painful to use. On top of that, the Swedish 50-year-old, who lost her hand in a farming accident, had been living with excruciating phantom limb pain for more than 20 years.
鈥淚t felt like I constantly had my hand in a meat grinder, which created a high level of stress and I had to take high doses of various painkillers,鈥� Karin said in a news release from the group that made her new prosthesis possible. The engineers and doctors who did this work are a part of the Centre for Bionics and Pain Research, a multidisciplinary collaboration between several international organizations.
To relieve her pain and to gain function, she agreed to be a part of an experiment that would give her a bionic hand. The team says she is the first person in the world with a below-elbow amputation to successfully get a bionic hand directly connected to her neuromusculoskeletal system.
Karin鈥檚 prosthesis is considered bionic because it is attached to her nervous system as well as to the muscle and bone, unlike a traditional prosthesis that attaches to the end of her stump through suction or a harness and cable system.
Although some other kinds of implants require external equipment, the bionic hand is completely self-contained. Surgeons embedded a controller, a wrist-shaped battery unit and a mechatronic coupler 鈥� a device used to transmit power 鈥� that connects to the neuromusculoskeletal interface, so she doesn鈥檛 need any additional equipment like a large battery or processing unit.
However, there wasn鈥檛 a lot of space in the area for everything to fit, so surgeons had to rearrange her muscle and nerves in what was left of her arm. They also eliminated the neuromas, the disorganized group of fibers that ball up at the end of a nerve when it is cut.
Dr. Max Ortiz Catalan, a co-author of the new study and head of neural prosthetics research at the Bionics Institute in Melbourne, Australia, said the neuromas are what can cause some of the phantom pain when people lose a limb.
To get the signals from the brain to the bionic hand to tell it what to do and to give it a sense of touch, doctors transferred a muscle graft from the woman鈥檚 leg to her arm so the nerves could reconnect to a natural target. Using the muscle also prevents the formation of new neuromas, Ortiz Catalan said.
Doctors then plant an electrode in that muscle, which works as a biological amplifier, boosting the electric signal from the brain into the hand, where AI algorithms inside the prosthesis interpret the signal and allow her to move the bionic hand. Because the nerves are engaged in this process, Karin also has a limited sense of touch through the bionic hand.
Now she鈥檚 able to hold and release objects with a wide variety of shapes, turn a door handle, pick up coins, prepare food, pack a suitcase and many more practical activities she couldn鈥檛 do well before. It鈥檚 worked for three years, a good sign that it has been well-integrated into her body, researchers say.
Since the nerves are involved in an activity, Ortiz Catalan said, it also significantly reduces phantom pain. Her phantom pain level dropped from a five to a three, the study said, and her stump pain vanished entirely. She said she鈥檚 also been able to sleep better.
鈥淲e鈥檙e expecting the pain to disappear,鈥� Ortiz Catalan said.
The hand has a fully customizable look. In Karin鈥檚 case, it intentionally looks like a robot鈥檚 so it can 鈥渂e shown and not hidden,鈥� said Dr. Francesco Clemente, managing director of Prensilia, the company that developed the hand.
鈥淲e wanted the users to be proud of what they are, rather than ashamed of what was lost,鈥� Celmente said in a news release.
Ortiz Catalan said this procedure in part developed out of his graduate school thesis, and he was thrilled to see that it can work.
鈥淚t鈥檚 been a long journey,鈥� he said.
Now he hopes to refine the technology and make it more accessible. He鈥檚 currently in Ukraine, where, he said, there are many more people who could benefit from a bionic hand.
鈥淲e鈥檙e still far away from Luke Skywalker鈥檚 hand,鈥� he said. 鈥淲e鈥檙e still not close to all the functions of a biological hand, but we definitely made a considerable step forward.鈥�
Dr. Jorge Gonzalez-Martinez, the Stuart Niles Rowe Chair in neurological surgery and the vice chair of the Department of Neurological Surgery at the University of Pittsburgh, said this is a 鈥渧ery important and impactful achievement from the group.鈥�
Gonzalez-Martinez, who did not work on this research but who has a team developing their own bionic hand and other robotic projects to help patients, said it鈥檚 an exciting time for rapid advances in bionic technology. Several groups in the US and abroad are looking for ways to create these bridges between the nervous system, the body and the brain that interface with machines that can restore function to parts of the body that no longer work or are missing.
鈥淚 think what the article shows is pretty much in the scope, is absolutely great to have this implantable device in the hand that can control it and can perform what we call the pinching movement, one of the most important functions of the human hand,鈥� Gonzalez-Martinez said.
Such movement improves quality of life, but he said it is still 鈥渧ery rudimentary.鈥�
鈥淭his is a very, very simple movement that allows us to grab stuff, but it does not give us sensory feedback,鈥� Gonzalez-Martinez said.
In other words, a human hand has the ability to know exactly how much pressure it needs to pick up a hot cup of coffee versus something heavier like a laptop, that requires more pressure. Gonzalez-Martinez鈥檚 group and others teams are working to give a bionic hand more sensory ability.
The next hurdle is also the expense.
Governments have invested in this bionic technology, but more private sector help will be needed to make this technology widely accessible, Goznalez-Martinez said.
For the patient in this study, though, her bionic hand 鈥� even with its limitations 鈥� has changed everything.
鈥淔or me, this research has meant a lot,鈥� Karin said in the news release. 鈥淚t has given me a better life.鈥�
