Targeted Muscle Reinnervation for Control of Myoelectric Arm Prostheses By. Rory Makuch

Need for a functional upper limb Prosthetic ● There are an estimated 1.7 million people in the United States alone that have had an amputation of some kind. ● Between 1988 and 1996, 68.6 percent of trauma related amputations were upper limb amputations. ● There are Three main types of arm prostheses Cosmetic- provide realistic looking replacement. Body Powered- use body and shoulder muscles to move arm prosthesis. Myoelectric....

Myoelectric Arm Prostheses ● Myoelectric prostheses are artificial limbs controlled through sensors connected to remaining muscles of the arm ● Sensors pick up Electromyograph signals which are processed and converted to movements by a computer. ● This method is sometimes not intuitive because the patient has to flex muscles not normally associated with a movement to complete the movement. ● Some patients cannot generate strong enough signals to be picked up. Others such as shoulder disarticulation amputees simply do not have the muscles necessary.

Targeted Muscle Reinnervation ● A surgical process where the residual nerves in the arm are transported to the shoulder upper chest or back. ● After months of recovery, nerve impulses from the brain to the amputated limb will activate the muscle areas that the nerves have been transplanted to. ● This new muscle activation serves as an amplifier for EMG signal detection. ● It allows patients without any arm muscles to be fitted with a myoelectric prosthesis, as well as allowing more intuitive control of the prosthesis.

Technical Information ● For testing twelve EMG electrodes are placed on the patient in the new muscular activation areas. ● When the patients think about a certain movement the activation of the EMG sensors is mapped and processed. ● This data is used to train a myoelectric prosthesis to perform different operations.

Testing ● This type of prosthesis interface is still in the research phase. ● Five amputees that had undergone targeted muscle reinnervation and five non amputees were chosen to test the interface. ● The first tests were done on a virtual arm, patients chose 11 arm motions including 3 different grips to attempt. ● The control subjects completed the motions 97% of the time and the amputees 88% of the time. ● Three of the TMR participants were then chosen to attempt to manipulate a real prosthesis. They were able to attain proficiency in the first day. With great improvement over two weeks.

Limitations ● One of the limitations of the device is movement reaction time. While the results are much better than without TMR, the reaction speed is nowhere near non prosthesis speeds. ● Weight of the device. The patient has to wear a small computer on their back for processing and retraining on the go. ● The amputation must be recent (within 10 years) and there cannot be severe nerve damage.

Sources coalition.org/fact_sheets/amp_stats_cause. html coalition.org/inmotion/nov_dec_07/history_p rosthetics.html / gcu4re7rrpq7mrxmmixvapkvwm27mt2daqiw p3eqs57th6slh5zspeyoe4t74d6rrmo62rhrcw 3d/ProstheticArmcrop.jpg c/ Y8