A Chicago-area man is set to become the first person in the United States to receive a bionic arm connected directly to his bone, nerves and muscles — an advanced prosthesis designed to be controlled by his own neural signals and return sensory feedback in real time.
The man lost his left arm above the elbow in a construction-site accident in 2016. Now, he is the first participant in a five-year osseointegration clinical study led by Levi Hargrove, PhD, director of the Regenstein Foundation Center for Bionic Medicine at Shirley Ryan AbilityLab and professor of Physical Medicine and Rehabilitation at Northwestern University Feinberg School of Medicine.
On July 15, in an eight-hour operation at Northwestern Memorial Hospital, a combined team of plastic and orthopedic surgeons — led by Jason Ko, MD, vice chair of clinical operations, Department of Surgery at Northwestern Medicine, and Terrance Peabody, MD, chair of the Department of Orthopaedic Surgery at Northwestern Medicine — implanted a titanium fixture into the bone of the man's residual limb and placed electrodes onto his muscles and around his nerves. The procedure was conducted under an investigational device exemption (IDE) from the U.S. Food and Drug Administration.
How It Works
Osseointegration is a technique in which a metal implant is anchored into a person's residual bone. Over several months, bone grows into the implant's surface, making it a structural extension of the skeleton. A second component then passes through the skin, allowing a prosthesis to attach directly to the bone, eliminating the socket that conventional prostheses rely on — and, by extension, associated discomfort, poor fit and limited range of motion.
The e-OPRA (Enhanced Osseoanchored Prostheses for the Rehabilitation of Amputees) system builds on that foundation by routing signals through the same implant. Electrodes placed on muscle record the electrical activity generated when a person intends to move, and those signals are decoded to drive the prosthesis. Separately, electrodes placed around peripheral nerves deliver stimulation that creates sensations perceived as coming from the missing limb. The study will evaluate whether that feedback improves how well and how naturally research subjects can use the arm.
"This is about the interface, not the arm," Dr. Hargrove said. "e-OPRA takes on two of the hardest problems in the field at once. It anchors the prosthesis directly to the skeleton, which eliminates the socket entirely, and it puts the electrodes on the muscles and around the nerves — where the signals are clean, stable, and can travel in both directions."
What's New
The study is the first to combine osseointegration, targeted muscle reinnervation (TMR) and pattern-recognition control using implanted electromyography (EMG) sensors and nerve cuff electrodes for sensory feedback. TMR — a surgical technique developed in 2002 by collaborators at Shirley Ryan AbilityLab and Northwestern Medicine that revolutionized the neuroprosthetics industry — reroutes nerves that once served the missing hand to remaining muscles in the residual limb, giving those nerves a place to produce signals a prosthesis can read.
Eight participants will be enrolled in the study. Surgeons at Northwestern Medicine are implanting the devices and, depending on each participant's history, performing TMR at the time of implantation or revising nerve transfers done previously.
Rickard Brånemark, MD, PhD — who developed the OPRA osseointegrated implant system on which e-OPRA is built — traveled from Sweden to Chicago and was in the operating room on July 15, providing technical guidance to the surgical team. He is chairman of the board of Integrum AB, whose U.S. subsidiary, Integrum Inc., is a study partner. Researchers at the University of Chicago, led by Charles Greenspon, PhD, are leading the sensory feedback component of the work.
The study is supported by an $8.7 million award from the National Institute of Neurological Disorders and Stroke (NINDS), part of the National Institutes of Health, through a phased mechanism designed to move early-stage neural technologies into patient trials.
Next Steps: Rehabilitation and Evaluation
Today, the man who underwent surgery July 15, as well as a prior surgery in preparation, is recovering as his body adapts to the implant.
“This e-OPRA surgery was unique because the implanted nerve cuffs will provide sensory feedback to the missing hand when the patient uses his new bionic arm, considered to be the ‘holy grail’ for neuroprosthetics,” said Dr. Ko, the lead study investigator for Northwestern Medicine. “The combination of a bone-anchored prosthesis, internal muscle and nerve electrodes represents a major advancement in prosthetic technology. Now, the electrical signals that control the bionic arm will not be affected by sweat, skin motion, swelling or other external factors that prevented our patient from successfully using a bionic arm previously.”
“These e-OPRA surgeries are another example of the decades-long teamwork and deep collaboration between Northwestern Medicine’s Orthoplastic Program and Shirley Ryan AbilityLab that are focused on advanced limb restoration and bionic reconstruction,” said Dr. Peabody. “The surgeries are technically demanding and require both the bone expertise from orthopaedic surgery and the soft tissue and nerve techniques pioneered by plastic surgery at Northwestern Medicine. Our patient’s surgeries were successful. He is recovering as expected and is very excited about what he is already able to do with his practice bionic arm.”
The research team can already capture muscle signals from the implanted electrodes — the signals that will eventually control the prosthesis. In the coming months, the man will begin rehabilitation at Shirley Ryan AbilityLab and training with the bionic arm. The study is expected to conclude in 2030, at which point results will be made publicly available.
