What is targeted muscle reinnervation?

A cutting-edge technology used to control prosthetic limbs is known as targeted muscle reinnervation (TMR). This technology was developed at the Rehabilitation Institute of Chicago, by Dr. Todd Kuiken.

To understand how TMR works, it is important to know how the muscles in your limbs are controlled. Your brain sends electrical commands down the spinal cord, which then go through peripheral nerves to the muscles. Imagine what would happen to this pathway if a limb had been amputated. The peripheral nerves would continue to carry electrical motor command signals that begin in the brain, but the signals would run into a dead end at the site of amputation and would never reach the amputated muscles.

The surgical procedure required for TMR redirects these amputated nerves to control a substitute healthy muscle in another part of the body. For instance, a surgeon might attach the nerves that once controlled a patient's arm to muscles in the patient's chest. Then, when the patient attempts to move the amputated arm, the control signals that going through the original arm nerve will instead cause some of the chest muscles to move.

The electrical activity of these chest muscles then can be sensed with electrodes and can be used to provide control signals to a prosthetic device. As a result, by just thinking of moving the amputate arm, the patient can cause the prosthetic arm to move instead.