Kuiken first got the idea for TMR when he was a graduate student during the 1980s. In his first patient, Kuiken took four nerves that had gone to the amputated arm and redirected them to the patients chest muscles. As a result, when the patient wants to close his hand a hand that is no longer there the impulse travels down the nerve, into his chest and causes the chest muscle to contract.
The next step was to use the muscle contraction in the chest to move the prosthetic arm. This was accomplished with the help of an electromyogram (EMG), which picks up the electrical signal that the muscle emits when it contracts.
The signal is directed to a microprocessor in the artificial arm which decodes the signal and tells the arm what to do. In their work thus far, Kuiken and his colleagues have programmed the processor in the prosthetic arm to recognize four signals to produce two arm movements: open and close hand and bend and straighten elbow.
The result" When the patient thinks close hand the hand closes. Contrast this with current motorized prosthetic arm technology: The patient has to learn to use new muscle groups to move the prosthetic arm; can perform only one movement at a time; and must contract two muscles at once to achieve a new movement.
Its not very common to flex your chest muscle to close your hand or bend your wrist, said Kuiken. Quite frankly, most people with a unilateral shoulder disarticulation amputation dont wear a prosthesis at all: Its just too cumbersome.
While TMR is more intuitive and natural, Kuiken and his team wanted to see if they could extract more of the wealth of information from the electrical signals produced by the nerves and chest mu
|Contact: Christine Guilfoy|
American Physiological Society