Bionics in Rehabilitation

Posted by Albert Holt, MD on March 9, 2011 under Rehabilitation | Be the First to Comment

Recently, I had the opportunity to learn about several different technological enhancements for amputees and paraplegics.  These devices seek to replace the functionality lost from catastrophic injury. 

At the Rehabilitation Institute of Chicago (RIC), Todd Kuiken, MD, PhD, has been developing a bionic arm that has been featured in multiple science and technology magazines.  The first patient to receive a bionic arm was a man who had both arms amputated because of an electrocution.  At the Center for Bionic Medicine (CBM) at RIC, Dr. Kuiken pioneered the muscle reinnervation procedure which takes an amputee’s own nerves and connects them to healthy muscle.  The “Bionic Arm,” or myoelectric arm, is operated through electrical signals from nerves transplanted from the affected limb into the pectoralis muscle of the amputated arm.  The user activates the arms through a learned conditioning using his own thought-generated nerve impulses.   These impulses are sensed, via surface electrodes, from the pectoral muscle and carried through to the mechanical arm, causing the arm to move.

The second bionic limb that I have seen is one that replaces the hand and fingers for people who have had their hands severed.  ProDigits has developed several different devices that serve to replace lost fingers.  These fingers can be powered by two types of control systems: myoelectric sensors that register muscle signals from the patient’s remaining finger or palm, or a pressure sensitive switch input (touch pad) that responds to the tissue surrounding the metacarpal bone to provide enough pressure to activate the digit.  There are different built in features that sense the grasping around objects so that the fingers do not crush the object.  This is part of the stall feature, which detects when digits close around an object, so users form different grip patterns.  The particular person that I observed had his fingers severed on both hands and therefore lost all of his grasping function.  Using the fingers, he was able to feed himself for the first time.

The third device was an exoskeleton known as eLEGS produced by Berkeley Bionics.  eLEGS is a wearable, artificially intelligent, bionic device that enables people with paralysis to stand up and walk again. The exoskeleton is battery-powered and rechargeable, fitting comfortably and securely over your clothing.  I observed one of their female test subjects, who has been paraplegic for almost two decades following a skiing accident, walk using the exoskeleton device.   She wrapped herself into the exoskeleton and was able to balance herself and walk.  The pace and control of walking could be enabled by devices that looked like ski poles/walking sticks that had an electronic connection to the exoskeleton.
Demonstration of eLEGS device.

Each of these devices are currently in the development and testing phases for use by injured people, and share similar features, including durability, self-contained power and specifically targeted functional replacement.  Eventually, the hope is that they will return functionality to people who would have required additional support from caregivers or others.  Currently, these devices are expensive.  As the technology improves and the cost per unit decreases, they are likely to become more available to amputees and spinal cord injured patients.

The interesting thing for rehabilitation centers will be how these devices become part of the rehabilitation process.  As an injured person is learning new routines for doing everything from feeding and combing their hair to walking, they go through a retraining process to compensate for the lost function from their injury.  As these devices continue to evolve, they will likely become an early part of the rehabilitation process.  I expect that over the next few years we will begin to see these devices incorporated into selected patients internationally.  Within the next decade, we are likely to see some of the technologies more widely available.