ACS Fellow Helps Advance Bionic Arm Technology

A Chicago-area patient has reached a surgical milestone toward receiving a bionic arm connected directly to bone, nerves, and muscles. The investigational approach aims to combine stable skeletal attachment with intuitive movement control and sensory feedback, addressing persistent limitations of conventional upper-limb prostheses.

During an 8-hour operation at Northwestern Memorial Hospital in Chicago, Illinois, earlier this year, surgeons implanted a titanium fixture into the patient’s residual upper-arm bone and placed electrodes on muscles and around peripheral nerves. 

ACS Fellow Jason Ko, MD, MBA, FACS, a plastic and reconstructive surgeon and Northwestern’s vice chair of clinical operations in surgery, co-led the team with orthopaedic surgeon Terrance Peabody, MD. The procedure was performed under an FDA investigational device exemption.

The e-OPRA system combines osseointegration, targeted muscle reinnervation, and pattern-recognition control using implanted electromyography sensors. 

Osseointegration provides direct skeletal attachment, eliminating the conventional prosthetic socket. Targeted muscle reinnervation redirects nerves previously serving the missing limb to remaining muscles, creating signals that can help control a prosthesis. The study will evaluate comfort and function with implanted electrodes and the effects of sensory feedback generated through peripheral nerve stimulation. 

Muscle electrodes record intended movements, while nerve cuff electrodes are designed to produce sensations perceived as coming from the missing hand. Dr. Ko explained that internal electrodes avoid signal disruption from sweat, skin movement, and swelling—factors that previously prevented this patient from successfully using a bionic arm.

Researchers already can record muscle signals from the implanted electrodes. Rehabilitation and prosthesis training are planned as recovery progresses. Eight participants will be enrolled, with study completion expected in 2030. Improvements in everyday function and sensory integration remain under evaluation.