New Limb-Loss Center to Incorporate Robotics, Tissue Engineering
From VA Research Currents Vol. 4, No. 8/Aug. 2004
VA's Rehabilitation Research and Development Service has awarded $4.7 million over five years to researchers at the VA medical center in Providence, R.I., to develop state-of-the-art care for veteran amputees, in collaboration with Brown Medical School and the Massachusetts Institute of Technology.
The new "Center for Rebuilding, Regenerating and Restoring Function After Limb Loss" will provide patient care and conduct research in tissue engineering, neurotechnology, materials science, robotics, and advanced surgical techniques. VA expects the center to significantly improve outcomes for recent combat-injured veterans and other VA patients who have lost limbs.
The initiative comes as the U.S. military has seen a sharp increase in the number of combat-related amputees. Due to advances in body armor and battlefield first aid, many soldiers who would otherwise have been killed in action are surviving, albeit with severe injury to their extremities.
Researchers at the center, led by orthopedic surgeon Roy Aaron, MD, will advance the concept of a "biohybrid" limb: an intricate meshing of restored and enhanced biological tissuesskin, bone, nerves, cartilagewith high-tech prosthetic components. The goal is to provide the amputee with a limb that functions as naturally as possible. Scientists with the program are even working on harnessing brain signals to directly control robotic limbs.
Much of the early work at the center will apply mainly to traumatic amputees. Veterans from around the country who are medically eligible will be accepted for treatment. But research at the center could eventually benefit a much wider population of veterans and other Americans with both upper- and lower-limb loss.
In one program at the center, VA and Brown orthopedic surgeons will perform a procedure known as the Ilizarov technique to lengthen the residual limb of above-knee or above-elbow amputees. The method so far has been used mostly on children with deformed limbs. It involves slightly separating the bone in the residual limb and implanting wires through the bone. The wires are connected to a rigid external frame.
The separated bone begins to naturally fuse together. However, at home the patient adjusts the frame at prescribed intervals to move the wires and separate the bone anew. Over time, this cycle of separation and healing lengthens the bone. Along with this, the VA-Brown team will explore ways to implant an "endoprosthesis"similar to a joint replacementto restore the knee or elbow's function. Researchers believe these surgical methods, combined with other therapies, may eventually enable doctors to transform an above-knee amputee into a below-knee amputee, or an above-elbow amputee into a below-elbow amputee, reducing complications and enabling greater mobility and control once a prosthesis is fitted.
Other teams at the center will explore tissue-engineering techniques to further restore the residual limb—such as cell transfer, encapsulated drug delivery and gene therapy. Another group will study osseointegration, a technique developed in Sweden wherein prosthetic components are affixed to specially implanted titanium bolts that integrate with the bone of the residual limb.
Some amputee patients at the center will be fitted with myoelectric component developed by bioengineer Hugh Herr, PhD, at MIT. These knee and ankle systems will rely on tiny sensors called BIONs (bionic neurons), developed by the Alfred Mann Foundation in California. These sensors, implanted in the residual limb, will read electrical signals from the patient's muscle and feed the information to an "onboard" microprocessor in the prosthetic device. As a result, the device will respond to the amputee's intent.
Further developing the concept of linking prosthesis and nervous system, a Brown-VA group led by neuroscientist John Donoghue, PhD, will seek to use mathematical algorithms to translate the brain's complex electrical impulses into signals that can control prosthetic limbs. In earlier studies with monkeys, Donoghue has shown that output from the brain can be used to control computer cursors almost as effectively as a natural hand. The work promises to benefit amputees as well as those with spinal cord injury or other conditions involving paralysis.
VA diabetes researchers documented VA's successesand areas needing improvementin a supplement to the May 2004 issue of Diabetes Care. The Seattle VA Epidemiologic Research and Information Center (ERIC) edited the supplement, which includes 16 articles. One study, for example, found that VA patients received an equal or higher level of preventive care compared to non-veterans or veterans receiving non-VA care.