In 2002, targeted hyper-reinnervation nerve transfer surgery was performed unilaterally
on a bilateral shoulder disarticulation amputee. The goal of this surgery was to create additional
sites using the remaining unused brachial plexus nerves to allow simultaneous control of
multiple movements using more natural control schemes [1,2,3].
As a result of the nerve transfer procedure, 4 new myoelectric control sites were created
on the left pectoralis muscle. Subsequent prosthetic fitting found that the user was able to
operate the elbow and hand in a coordinated fashion using three electrodes. Various outcome
measurements showed an improvement in prosthetic function.
However, with the increase in the number of input signals, a goal was set to build a
prosthesis with the maximum number of controlled motors available. Six motorized components
were identified: three were commercially available in the USA, one was commercially available
in other countries and two were a research prototype