First Subject Receives Implantable Myoelectric Sensor in FDA Study

Illustration of the IMES System courtesy of The Alfred Mann Foundation.

The Alfred Mann Foundation (AMF), Valencia, California, announced that U.S. Marine SSgt. James Sides is the first recipient of the Implantable Myoelectric Sensor (IMES) System, which holds the promise of being the first minimally invasive, intuitive, multichannel prosthetic control system that is intended for long-term use. The IMES System is currently being studied under the Investigational Device Exemption (IDE) regulations of the U.S. Food and Drug Administration (FDA). AMF is conducting its ongoing trial with injured veterans at the Walter Reed National Medical Military Center (WRNMMC), Bethesda, Maryland.

The IMES implants are small capsules about 16mm long and 2mm wide, and they are placed into the residual muscles of an amputated limb where they detect contractions that are used to elicit specific movements in the part of the limb that is no longer there. These signals are captured and wirelessly transmitted from the implanted sensor to a decoder box, which serves as an electronic brain. The IMES System bridges the brain to the prosthetic limb, enabling the signals sent from the brain to the amputated limb's residual muscles to control the prosthesis intuitively without the need for invasive brain or muscle reinnervation surgery.

The IMES System currently provides up to three degrees of freedom that can occur simultaneously: opening and closing the hand, rotating the wrist, and moving the thumb. Future systems are targeting up to 13 simultaneous degrees of freedom and the ability to combine preprogrammed patterned movements that would potentially enable advanced prosthetic devices to achieve performances that in many instances will be as fluid and effective as an intact limb.

The IMES system is intended to address many of the shortcomings of current myoelectric control systems, AMF said. Because the muscle signals are detected by electrodes placed on the surface of the skin, factors such as sweat, movement between the electrode and the skin, and limited access to only large muscles close to the surface of the skin limit the function of the current myoelectric control systems.

"I am deeply committed to improving the health and well-being of my patients," said Retired Army Colonel Paul F. Pasquina, MD, principle investigator and chair of the Department of Physical Medicine & Rehabilitation at the Uniformed Services University, Bethesda, and former chief of orthopaedics and rehabilitation at WRNMMC.

"I was thrilled with the idea of collaborating with AMF and leading the IMES project. It holds great promise for the future of amputees and overcomes several of the flaws that exist with the other 'thought-controlled' systems available today. I couldn't be happier with how quickly our first subject has adapted."

"This is exciting and promising work, and the AMF team of IMES investigators are confident that this technology will result in a new and improved class of prosthetic devices for both upper and lower limb amputees," said David Hankin, CEO of AMF."

Editor's note: This story was adapted from materials provided by AMF.