Human Fusions Institute faculty member Emily Graczyk and her lab recently celebrated the success of their first neural interface implantation surgery for their study aiming to restore sensation to people with limb loss. The surgery utilized a new surgical approach that was developed by the team to enable the implantation of the system in people with short residual limbs due to traumatic amputation. “This is a big step for the program and could open the door for inclusion of future participants with shorter transhumeral amputation or other conditions affecting limb size, volume, and integrity,” said Graczyk.
HFI Ph.D. student Jonah Mudge led the technical aspects, while fellow PhD student Roberto Peralta led cadaver studies that helped the team visualize the new approach while planning the surgery. PhD students John Wright and Leah Roldan also assisted with planning.
Two 16-channel composite flat interface nerve electrodes (C-FINEs) were implanted around the median and radial nerves of the participant. Stimulation through contacts in the C-FINE will produce touch and movement sensations in the missing limb. Intramuscular electrodes were also implanted in muscles in the residual limb, including the biceps, triceps, pectoralis major, and latissimus dorsi. All electrodes were implanted from a single site, and this appeared to save time and reduce lead routing complexity. This allowed the surgeons to avoid incisions or tunneling within the limb. Graczyk’s team planned out the lead routes and connector sites before and during the surgery, ensuring that the positions of subcutaneous components would be comfortable and that lead routes would have minimal strain and fatigue.
Graczyk reported that the study participant had some soreness after the surgery but was overall "in good spirits." He will return to Cleveland next week for a wound check and the initial stimulation mapping session. “I look forward to all we can learn from this participant about the impacts of electrode position on sensation location, selectivity, and modality, in addition to the multitude of other scientific questions we have about sensorimotor integration in upper limb prostheses,” said Graczyk.
Graczyk praised HFI Director Dustin Tyler for his “vision and leadership that enables this entire program to be possible.” She also thanked CWRU biomedical engineer Jeremy Dunning for his assistance with electrode procurement and sterilization.