Myoelectric upper extremity prostheses with multi-articulating hands can provide an array of benefits for users. However, many users struggle with achieving the grip patterns through myoelectric signals, and candidates are typically limited to transradial amputees with a long residual limb.
To make this technology more useful for amputees, researchers at Infinite Biomedical Technologies (IBT), a medical device company in Baltimore, have created the MORPH system, which aims to simplify the use of myoelectric devices.
IBT was founded by researchers from the Johns Hopkins Neuroengineering and Biomedical Instrumentation Lab in 1997 as a way to translate research from their lab to the marketplace. IBT still has a close relationship with JHU and Nitish Thakor, PhD, a founding member of IBT and director of the Neuroengineering Laboratory.
“One of the thoughts was we could combine the benefits of RFID [radiofrequency identification technology] control, which is wireless switching between different settings or scenarios, with the needs of prosthetic hands on the market,” Rahul Kaliki, PhD, chief executive officer of IBT, told O&P Business News. “Especially in the upper limb market, there are a lot of new hands that come out that have all of these multiple degrees of freedom, but the issue is with the lack of available control technologies, you are only able to access maybe four at most of the potentially 24 grips.”
IBT developed the MORPH, which stands for myoelectrically operated RFID prosthetic hand. RFID technology uses radio frequency to wirelessly transfer data, such as information stored in barcodes, and the MORPH utilizes this wireless transmission to send signals to the hand and dictate grip patterns.
“It looks like a hockey puck that plugs into the back of a prosthetic hand,” Kaliki said. “The little hockey puck has an antenna on the back of it, and that antenna actually emits a radio frequency field, and if you bring an RFID tag into that field, it detects it.”
The tags are programmed to a certain grip pattern, so when the hand encounters a tag, it will detect the signal and activate the designated grip pattern.
“It is easy because just coming in contact with the tag will instantly and consistently make that grip pattern change happen, and then it doesn’t shift out of that grip pattern until I touch it on the tag,” Sean McHugh, one of the first wearers of the MORPH system, said.
McHugh, who became a unilateral transradial amputee after a construction accident 11 years ago, met Kaliki and the rest of the IBT team at an upper extremity rehabilitation event several years ago and volunteered to participate in their studies involving pattern recognition.
McHugh wears the iLimb Pulse (Touch Bionics), but always struggled with achieving the double and triple impulse commands.
“I was able to perform the co-contraction with fairly decent accuracy, and I was able to do the hold open command, but the double impulse and triple impulse were always extremely elusive for me,” McHugh said. “They were difficult to achieve, and I would say I only had maybe a 10% success rate.”
Source: Infinite Biomedical Technologies
However, once he added the MORPH system to his device, he noticed a significant improvement.
“I wasn’t using the hand to its full potential, but with the MORPH system, the way the RFID tags trigger those grip pattern changes, it is so precise and instantaneous, and it’s accurate every time,” McHugh said. “It has taken away the unpredictability. The hand now, instead of just being an interesting toy, has truly become a functional tool, because I can now use it reliably.”
McHugh places tags around his home and work environment in locations where he frequently uses a particular series of grip patterns. For example, he has three tags on his coffee maker to achieve the three hand grips necessary to operate the machine, a tag in his closet that places the hand in thumb park mode so he can easily slide his arm into a sleeve and a tag at his work station to activate the index point grip and type on a computer.
“I also started to take the tags with me and just carry them,” McHugh said. “Simply by wearing a shirt with two breast pockets, I could put a tag in each pocket, a tag in the pants pocket and a tag on my belt, so I am still carrying all of the potential with me.”
Fellow MORPH user Mike Benning has also had success with the system. Benning, a business development associate for Hanger Clinic in the greater Boston area, met the IBT team at the 2012 American Orthotic and Prosthetic Association National Assembly, and he was brought on as a tester and fitted with the device in January.
When he first received the MORPH, Benning, who lost his arm to cancer in 1979, had recently been fitted with the iLimb Ultra. The MORPH system helped him better adjust to the myoelectric technology.
“I was able to see the perfect signal on the Touch Bionics software because it gives you a real time graph of the signals,” Benning said. “I was having challenges with the co-contraction and the double pulse and triple pulse. But with the MORPH, when I would swipe the card over the receiver, I would look at the real time graph of the signal that the MORPH would generate, and I was able to mimic that signal visually.”
Since then, Benning has been fitted with the iLimb Ultra Revolution, the first person in the United States to receive this prosthesis, and he said the combination of the two technologies has been incredible.
“My world increased exponentially when I got my myoelectric, and then you add the MORPH on top of that, and it has been amazing,” Benning said. “It was liberating and empowering.”
Benning also places tags in strategic locations to maximize the use of his hand. He has a slim tag resembling a business card taped to his cell phone that activates his own cell phone grip pattern, and he keeps another tag in his wallet that rotates the thumb and activates a lateral grip position so he can pull a card out of his wallet.
More use from myoelectrics
The MORPH technology can potentially increase the number of users that will now be able to use myoelectric prostheses.
“It definitely works for people with short residual limbs, or who lack great muscle control and bilateral amputees,” Kaliki said.
Benning, for example, is not a typical candidate for a myoelectric prosthesis, because his residual limb is only 33-mm long. However, the MORPH system helps him achieve triggers that were not previously available to him.
“The MORPH makes it so much easier and quicker, so I don’t have to be perfect with my signals every time,” Benning said. “To be able to swipe a card or my wallet or cell phone right over it is huge for me.”
The MORPH system can also extend the amount of time that a user can wear a myoelectric prosthesis, because it can aid fatigued muscles.
“I am a very active user of my prosthesis, and I wear it 8 hours to 14 hours a day,” Benning said. “And sometimes at the end of the day, my muscles are very fatigued. So the MORPH is a good crutch to get me back to normal and get me through a grip pattern quickly and easily.”
Both McHugh and Benning said since adding the MORPH system, they have increased the amount of time they wear their myoelectric prostheses.
“It’s not something I wear once a month like I used to,” McHugh said. “Now I wear it every day and use it more and more as time goes by.”
Benning agreed, adding that he has worn his cable-operated prosthetic arm twice since being fit with the iLimb and MORPH system.
“I actually find myself more willing to wear my prosthesis,” McHugh said. “I don’t dread putting it on in the morning, and I find when I come home at night, I am not as eager to remove it as I was with my harness and cable.”
The MORPH system was released on June 1. The introductory price is $4,000 per unit, but according to Kaliki, there are several insurance codes under which the device may be covered, such as an electronic switch or microprocessor unit. — by Megan Gilbride
Disclosures: Kaliki is the chief executive officer of Infinite Biomedical Technologies, the maker of the MORPH system. Benning is a business development associate for Hanger Clinic. McHugh reports no relevant financial disclosures.