Morgan, from Nova Scotia, suffered a traumatic industrial workplace injury which resulted in an above elbow amputation and damage to his left ankle. He underwent complex surgery, and overcame many complications, including infections and issues related to the healing of his injuries. He first came to see us in June 2011. At that time, his body was not yet ready to begin fitting but we were able to assess his needs and hopes for rehabilitation.
He wanted a powered arm and hand that would help him return to work and enjoy his hobbies, including managing chores around the house, taking care of his dogs, and getting back to the gym – and he wanted it to “look cool” – black carbon fiber – nothing that resembled skin.
Initially his residual limb proved difficult to work with. This is the part of the arm that would control his ability to open a prosthetic hand. It was decided that the best option for prosthetic fitting was to have his residual limb surgically re-shaped to bring the muscle closer to the surface and improve myoelectric control.
At the same time, we (the clinic team including the physiatrist) consulted with surgeons at Edmonton’s Glenrose Rehabilitation Hospital regarding a new surgical technique called Targetted Muscle Reinnervation (TMR), where the nerves that previously populated the hand could be re-routed into other muscles in an upper arm to create more usable muscle sites for improved intuitive control. For example, if Morgan wanted to open his hand, he would think, “open hand”, and the nerve that previously controlled that action would respond in the new muscle. This is more intuitive than flexing a tricep muscle to open a powered hand.
Morgan underwent the TMR surgery in April 2012. During surgery a lot of the excess tissue was removed and his limb was reshaped. The TMR became complicated as the muscles the surgeons intended to use to re-implant the nerves were not large enough to use for this purpose, so the nerves were implanted into sections of Morgan’s chest muscle, the pectoralis.
Once Morgan was sufficiently healed our team began the process for his fitting, using a myoelectric arm with a powered elbow (Boston Digital Arm), powered wrist and powered hand (I-limb by Touch Bionics). Ultimately Morgan was only able to use the bicep and tricep muscles in his upper arm to operate the hand, and a linear transducer (acts like an electrode but uses very small body motions to activate it) on a harness to operate the elbow.
Initially he used only the hand and elbow until his muscles strengthened. Now that Morgan has regained strength, he is able to use both muscles together (co-contraction) to activate the powered wrist, and he is able to use other combinations of muscle impulses to activate different grips that the hand is capable of (such as a pinch grip or pointer finger).
Morgan has returned to work, and uses his prosthesis with a powered work device (greifer) to help hold the tools and equipment of his trade. He wears his arm socially and it helps him to accomplish many household tasks such as repairing/maintaining things around his house and preparing meals. He also finds his arm very useful for carrying grocery baskets when shopping.
To take advantage of the TMR surgery and his newly re-innervated chest muscles (which now feel like his hand), we have started using a control system that was developed here at UNB, called Pattern Recognition, which takes information (through electrodes) from many muscles, and identifies patterns that are distinct from each other when a person undertakes various actions. In Morgan’s case, we are using muscles in his upper arm and asking him to move his elbow up and down, and to move his wrist.
These are the muscles that would naturally be used for these actions. We are also using his chest muscles and asking him to open and close his hand, which is now where those nerves are located, so he actually feels like he is opening and closing his hand when he does this action. This control system has never been used before in Canada in an actual prosthesis, (although a version of it is being used in Chicago at the Rehab Institute of Chicago in clinical trials) and we are close to being able to test it clinically. Morgan is thrilled to be a part of this important research.