Prosthetic limbs can make a world of difference for amputees. Regained mobility and independence are almost priceless. However, current prostheses often come with aggravations and problems. Most prosthetic arms, for example, have to fit into a prosthesis socket. The sockets can loosen in time and can cause skin problems. Attaching and removing the prosthesis can also be awkward and difficult. Depending on the socket location, the prosthesis range of motion also can be limited.
Medical researchers at Radboud University Medical Center have devised a technique to attach a prosthetic arm to nerves by connecting it directly to the arm stump bone. They have used the technique with legs since 2009 and now with an arm. Called a “click-on robotic arm,” the prosthesis actually clicks into place on a metal rod implanted in the bone. By connecting directly to tissue and nerve cells, without an intervening prosthetic socket, patients can eventually learn to control the prostheses with their minds. Another advantage of a click-on arm is the range of motion is greater because patients can control movement with their shoulder, which isn’t always possible with sockets.
The process requires three surgeries. First, a metal rod with a rough surface is implanted in the bone. The rough surface strengthens the rod’s embedding. After six to eight weeks, a hole is punched in the skin and a second rod is attached to the embedded rod. The connecting rod protrudes slightly from the skin so the prosthesis can click onto it. The third procedure is Targeted Muscle Reinnervation (TMR) surgery. A plastic surgeon attaches nerves that previously controlled the hand and underarm muscles to parts of muscles in the stump. The muscles act like amplifiers for the nerve signals.
The series of surgeries and the rehabilitation and training periods are lengthy and strenuous for patients, but the eventual rewards are greater control, more comfort, and enhanced independence and freedom.