JAMA Article Shows Targeted Muscle Reinnervation Patients Have Greater Control of Prosthetic Arms
Study demonstrates how to suppport greater control of prosthetic arms.
The Rehabilitation Institute of Chicago (RIC), the nation’s #1 rehabilitation hospital, announced its Center for Bionic Medicine has harnessed a new pattern recognition technique that allows quicker and more refined control for myoelectric arms used in combination with the Targeted Muscle Reinnervation (TMR) procedure, which allows patients to control prosthetic arms simply by thinking about it.
A study released by the Journal of the American Medical Association (JAMA), found that through a technique called pattern-recognition control, researchers can harness more neural information from patients who have had the TMR procedure and decode those neural signals to allow patients real-time, multiple-degree control of advanced prosthetic arms.
“The use of pattern-recognition control is an exciting advancement for patients with arm amputations. It will allow us to decode more neural information from the patients providing enhanced, more natural operation of their prostheses,” said Todd Kuiken, MD, PhD , director of the RIC Center for Bionic Medicine. “This neural interface, used in combination with DARPA’s new sophisticated prosthetics, is creating better patient independence and supporting RIC’s vision to advance human ability.”
Amanda Kitts, 40, lost her left arm below the shoulder in a car accident in 2006. Immediately, Kitts and her husband found out about RIC’s TMR procedure and made an appointment to see Dr. Kuiken. Months later, Kitts came to RIC to have the TMR procedure, which rewired the nerves that once went to her left arm and hand, to skin and muscle in her remaining bicep muscle. A myoelectric prosthetic arm fits over her residual limb, and electrodes conduct the neural signals to the arm so that when Kitts thinks about moving her arm or hand, it moves. She has been participating in research trials at RIC since 2006 and was able to wear the DEKA Research arm as part of the JAMA study.
“I was amazed at the level of hand function and how fast I was able to control the arm and hand,” said Kitts. “I was able to pick up a penny off the table and could catch an object in motion like a checker that was rolling across the table. It’s really amazing to be able to just think about it and have my prosthetic move so quick.”
About the JAMA Study
The study assessed five upper-arm amputees who have had the TMR procedure at RIC and five control participants without amputations. All participants were instructed to perform various arm movements, and their abilities to control a virtual prosthetic arm were measured. The average motion selection times for elbow and wrist movements (elbow flexion/extension, wrist rotation, and wrist flexion/extension) were 0.22 seconds for TMR patients and 0.16 seconds for control participants. The average motion completion rate for elbow and wrist movements was high (96.3 percent for TMR patients and 100 percent for control participants). The average motion completion times for elbow and wrist movements were 1.29 seconds for TMR patients and 1.08 seconds for control participants. For both groups, hand grasps took longer to complete than arm movements; the average motion completion times for hand grasps were 1.54 seconds for TMR patients and 1.26 seconds for control participants.
Three of the patients used advanced prostheses, including motorized shoulders, elbows, wrists and hands, developed by John Hopkins University Applied Physics Lab (JHUAPL) and Deka Research, Inc as part of the Defense Advanced Research Projects Agency (DARPA) Revolutionizing Prosthetics Program launched in 2006.
Patients must be medically evaluated to see if they are right for the procedure. In general, patients must meet the following criteria:
TMR is a surgical procedure, conducted by Dr. Greg Dumanian, now available to any amputee who is medically appropriate. This surgery takes the nerves that once went to an amputee’s arm and hand and transfers them to new muscle; it essentially rewires the nerves and muscles. Electrodes sit on the skin over the muscles and connect to a myoelectric prosthetic arm, so when the patient thinks to move his or her arm, the nerves send the signals to that reinnervated muscle area, the electrodes pick up the muscle signals and tell the computer in the arm what to do. This procedure, developed at RIC, has been done in more than 30 patients worldwide and is successful in providing more natural, improved control for myoelectric prosthetic arms.
Amputation above the elbow or at the shoulder within the last 10 years. Ideal candidates will have had their amputations in the last five years.
Children must be at least 14 years old and meet a minimum weight requirement.
Those born missing part or all of their arm and those suffering nerve damage, degeneration or paralysis are not candidates for this procedure at this time.
Successful use of a powered device is beneficial.
To learn more about TMR , or to determine if you are a good candidate for the procedure, please call 312-238-6035.
About The Rehabilitation Institute of Chicago
The Rehabilitation Institute of Chicago (RIC) is making a difference in the world for people with disabilities. RIC provides world-class care to patients from around the globe for a range of conditions from acute brain and spinal cord injury to chronic arthritis, pain and sports injuries. RIC, founded in 1954, has been designated the “#1 Rehabilitation Hospital in America” by U.S. News & World Report every year since 1991 and attributes its leading standard of care in part to its innovative research and discovery, particularly in the areas of bionic medicine, robotics, neural regeneration, pain care and better outcomes. RIC operates its 165-bed, Flagship hospital in downtown Chicago , as well as a network of 30 sites of care located throughout the city and surrounding suburbs that provide additional inpatient care, day rehabilitation and outpatient services. RIC also maintains strategic alliances with leading healthcare providers throughout the state of Illinois and Indiana.
 U.S. News & World Report has ranked RIC the “#1 Rehabilitation Hospital ” every year since 1991.
Robotics Trends would like to thank the Rehabilitation Institute of Chicago for permission to reprint this article. The original article can be found at http://www.ric.org/aboutus/mediacenter/press/2009/0210.aspx.