A Colorado resident, Les Baugh, has had an unfortunate past. In an electrical accident, some 40 years ago, he had lost both of his arms. However in a surprising turn of events, Baugh, today, has become the world’s first bilateral shoulder-length amputee to successfully wear and control a pair of John Hopkins University Applied Physics Laboratory’s Modular Prosthetic Limbs (MPL). What is more, he can operate the artificial limbs by merely thinking about doing so.
The MPL signifies the decade-long effort by Applied Physics Laboratory (APL), in the form of the Revolutionizing Prosthetics Program, to develop highly sensitized and advanced prosthetic limbs. In June, this year, APL conducted further tests to assess the feasibility of this technology. For this, the scientists had to first perform a specialized surgery, on Baugh, called targeted muscle reinnervation. Speaking about the surgery, Albert Chi, a trauma surgeon at John Hopkins University, said:
It’s a relatively new surgical procedure that reassigns nerves that once controlled the arm and the hand…By reassigning existing nerves, we can make it possible for people who have had upper-arm amputations to control their prosthetic devices by merely thinking about the action they want to perform.
In a video, recorded by the APL team, Baugh is seen saying:
I went into the surgery knowing that he was going to move nerves in my chest. I remember when I first [came] out from under it, the pain, I’d never had, I don’t even remember the original being that much excruciating pain but I imagine probably that my mind blocked that anyway.
Following this, Baugh underwent a series of training sessions at the Laboratory, the first of which was pattern recognition. In this, the researchers worked with a set of algorithms to individually locate and identify the muscle contractions. With the help of the system, they were able to learn how each muscle communicates with another. The acquired data were later used to achieve actual movements of the prosthetic limb. Chi said:
We take that information and translate that into actual movements within a prosthetic.
Before the artificial limbs were to be attached, Baugh was fitted with a custom-made socket that is, in turn, capable of establishing new neural connections with the re-innervated nerve cells. Meanwhile, Baugh was made to familiarize himself with the pair of prosthetic limbs, by means of a virtual-reality program known as Virtual Integration Environment (VIE). The program accurately simulates each and every aspect of the limbs, thus providing the researchers with an advanced brain-computer interface. The final step of the process was securing the limbs to the sockets. Talking about the experience, Baugh said:
Once the training sessions were complete and they released me and let me be the computer, basically, to control that arm, I just went into a whole different world.
The activities designed for the task were taken directly from our day-to-day life. Not only did Baugh manage to move a number of objects from one position to another, he successfully moved an empty cup from a lower shelf to a higher one. In order to complete just the last task, one requires perfect coordination of as many as eight muscle motions. What makes the MPL vastly different from other prostheses currently available in the market is that it is far more intuitive than ordinary prosthetic limbs. Containing more than 100 sensors, the MPL allows the user to move the limbs by simply thinking about doing so. Another remarkable feature of this technology is the fact that Baugh could acquire substantial control over the limbs with just 10 days of training. Courtney Moran, an APL-employed prosthetist, said:
We expected him to exceed performance compared to what he might achieve with conventional systems, but the speed with which he learned motions and the number of motions he was able to control in such a short period of time was far beyond expectation…What really was amazing, and was another major milestone with MPL control, was his ability to control a combination of motions across both arms at the same time. This was a first for simultaneous bimanual control.
The researchers believe that the patient will be able to gain greater control over the pair of prosthetic limbs by integrating them into his everyday life. For Baugh, it has been more of a dream come true. He said jubilantly:
Maybe for once I’ll be able to put change in the pop machine and get pop out of it. [Like the] simple things that most people don’t think of. And it’s re-available to me.
To learn more about Modular Prosthetic Limb, visit APL’s Revolutionizing Prosthetics page.