FITTING AND OUTCOMES OF A BILATERAL SHOULDER DISARTICULATION AMPUTEE FOLLOWING TARGETED HYPER-REINNERVATION NERVE TRANSFER SURGERY

to be controlled; yet there are fewer control signals remaining to control these multiple degrees-of-freedom. Traditional fitting of a shoulder disarticulation amputee with a myoelectric system uses 2-sites and sequential control. This can be tedious and slow. When an amputation has occurred, the musculature is gone, however, the nerves that controlled the arm remain. The goal of the targeted hyper-reinnervation nerve transfer surgery was to create additional sites using these nerves to allow simultaneous control of multiple movements using more natural control schemes [1,2,3]. Following an experimental nerve transfer procedure, 4 new myoelectric signals were created on the left pectoralis muscle for a single bilateral shoulder disarticulation (BSD) amputee using nerves that previously controlled hand and elbow function. Subsequent prosthetic fitting found that the user was able to operate the elbow and hand in a coordinated fashion and various outcome measurements showed and improvement in prosthetic function

TRANSHUMERAL LEVEL FITTING AND OUTCOMES FOLLOWING TARGETED HYPER-REINNERVATION NERVE TRANSFER SURGERY

In a typical transhumeral myoelectric system, biceps and triceps control both elbow and hand. Mode selection (frequently co-contraction) is used to switch between these two functions. In addition to requiring that these movements be performed sequentially, use of the biceps and triceps is not physiological for control of the hand. A novel approach for simultaneous control of multiple myoelectric functions was developed. This was made possible by ‘Targeted Reinnervation’; a surgical intervention, which involves the transfer of the peripheral nerves that used to provide signals to the forearm for hand function, to remaining muscles on the transhumeral limb

OCCUPATIONAL THERAPY OUTCOMES WITH TARGETED HYPER-REINNERVATION NERVE TRANSFER SURGERY : TWO CASE STUDIES

The control of prostheses, both externally powered and body powered, increases in complexity with higher levels of amputation. The externally powered prosthesis has a limited number of options for controlling multiple joints myo-electrically. Some method is necessary to switch control between functions (ie: elbow and hand). Targeted hyper-reinnervation nerve transfer surgery has the potential to greatly improve control of the electric prosthesis for the above elbow and shoulder disarticulation subjects by increasing the number of control options available. When the limb is lost the Brachial Plexus typically remains intact. The nerve supply to the missing limb is viable and connected to the motor cortex, but the motor end points served are gone. In nerve transfer surgery, the peripheral nerve is relocated to an area of denervated muscle tissue in the residual limb –a muscle that no longer moves the missing limb. Hyper-reinnervation occurs resulting in an area of say the Biceps, being controlled by the Median Nerve (in the intact limb, the Median Nerve supplied finger and wrist flexors). A muscle contraction occurs in the graft area of the Biceps when the subject attempts to close his hand. A myo-control site is added if the subject can isolate the contraction from that of the Biceps muscle served by the Musculocutaneous Nerve distribution

SHOULDER DISARTICULATION FITTING WITH 6 INDEPENDENTLY CONTROLLED MOTORS AFTER TARGETED HYPER-REINNERVATION NERVE TRANSFER SURGERY

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