Neuromuscular Lab

The Neuromuscular Lab is uniting biotechnology and surgical science.

Current Research in the Neuromuscular Lab

Research in the Neuromuscular Lab, led by Stephen Kemp, PhD, Paul Cederna, MD, and Theodore Kung, MD, focuses on functional neural control of prosthetic limbs and the amelioration of pain associated with peripheral nerve injuries and their consequences, including neuroma. Unlike the nerves of the central nervous system, peripheral nerves regenerate. How that process occurs and developing novel biotechnology and surgical approaches to improve patient outcomes following peripheral nerve injuries is what we do. Our approach is highly multidisciplinary, spanning basic science to translational medicine and is funded by such organizations as the National Institutes of Health, Office of Congressionally Directed Medical Research Programs, the U.S. Department of Defense Defense Advanced Research Projects Agency and The Plastic Surgery Foundation. Research in the Neuromuscular Laboratory includes investigators from within and outside the U-M Medical School to integrate advances and technologies across biology, engineering, materials science, electronic systems, plastic and neurosurgery. Clinically, faculty in our lab work with patients who have suffered peripheral nerve injuries, including those who have lost a limb.

Notably, our group of investigators was the first to develop a stable biologic nerve interface between an individual and an upper extremity prosthetic limb that can improve device control. Our ultimate goal is to use these regenerative peripheral nerve interfaces, or RPNIs, to provide closed loop neural control of prostheses, including sensory feedback, and for the treatment and prevention of painful neuromas that often develop in patients following amputation. Our research and the surgical procedures we’re developing are already impacting the standard of care for patients who suffer peripheral nerve injuries.

The Problem

Each year in the United States, over 185,000 individuals undergo amputation – close to 500 per day – and nearly 2 million overall have lost an extremity. While upper extremity prosthetics have advanced over the years, a critical problem remains: patients are unable to control their device beyond simple movements such as grasping an object, and they receive no sensory feedback. This makes many everyday tasks such as carrying a child, shaking hands or playing an instrument difficult and, for many patients, impossible.

In addition, most patients who have undergone an amputation develop extremely painful growths of regenerating peripheral axons. Lacking a “home,” or biological target to grow into, the axons regenerate in a disorganized fashion, causing benign peripheral tumors known as neuromas. About half of patients who develop neuromas experience severe and chronic pain. Among these patients, sleep disturbances, depression and other mood disorders often follow, impacting patients’ independence, productivity and relationships. While the medical literature has described more than 150 treatments for neuromas, none has been proven consistently effective. Much to the dismay of patients and the health care professionals who treat them, no gold-standard treatment has existed.

The Pathway

Investigators in our lab believe the way to address these issues is through the interface between the individual and the prosthetic. The interface is critical since it can serve as the locus for residual peripheral nerves to transmit both afferent and efferent signals – incoming sensory and outgoing motor signals, respectively – and do so strongly enough that the prosthetic can detect them, even amid electrical noise. The biologic interface, or regenerative peripheral nerve interface (RPNI), our lab has developed harnesses the natural behavior of motor axons, which target muscles to innervate. This enables us to optimize the interface for improved prosthetic control. We have developed a similar interface for residual sensory nerves, termed the dermal sensory interface (DSI), leading to improved sensory feedback as well. These two research efforts have in turn led us to discover that these interfaces can also help treat and even prevent the formation of neuromas.

Contributions to Science

Our contributions include:

  • Development of a novel biotic-abiotic interface, capable of controlling prosthetic limbs and hands. This construct amplifies neural signals and, through wireless electrodes, can communicate with a prosthetic limb leading to high-fidelity motor control.
  • Development of a novel surgical technique to treat neuromas with no instances in our patients to date of regrowth.