Myoelectric Prosthetics for Shoulder Amputees: New Study

Amputation can be a successful treatment for certain traumatic brachial plexus injuries when surgical reconstruction fails and, in those cases, myoelectric prosthetics can deliver effective grasp and release functionality, according to a new JBJS study.

The study, “The Role of Amputation and Myoelectric Prosthetic Fitting in Patients with Traumatic Brachial Plexus Injuries,” was published online June 2022 in the Journal of Bone & Joint Surgery.

For this study, the Mayo research team compared outcomes for patients with traumatic plexus injuries after elective amputation following unsuccessful surgical reconstruction or delayed presentation. In addition, the team looked for evidence of whether (or not) myoelectric prosthesis using nonintuitive controls was feasible and functional for patients.

The Mayo team collected data about the enrolled patients for at least 12-months. This was a retrospective review and just the Mayo Clinic in Rochester, Minnesota. In total, the team collected data on 32 patients with an average follow-up of 53 months. They documented 18 transhumeral amputations, 2 transradial amputations and 2 wrist disarticulations. In addition, they included 29 pan-plexus injuries, 1 partial C5-sparing pan-plexus injury, 1 lower-trunk with lateral cord injury and 1 lower-trunk injury.

The team found that amputations occurred on average at 48.9 months following the injury and 36.5 months after final reconstruction. Ten patients were fitted with a myoelectric prosthetic with electromyographic signal control from muscles not normally associated with the intended function. Others were fitted with a traditional prosthesis.

Average Visual Analog Scale pain scores decreased post-amputation: from 4.8 pre-amputation to 3.3 for the prosthesis group and from 5.4 to 4.4 for the non-prosthesis group. Average scores on the Disabilities of the Arm, Shoulder and Hand questionnaire decreased post-amputation, but not significantly. It decreased from 35 to 30 for the prosthetic group and from 43 to 40 for the non-prosthetic group.

“Patients were more likely to be employed following amputation than they were before amputation. No patient expressed regret about undergoing amputation. All patients in the myolectric prosthesis group reported regular use of their prosthesis compared with 29% of patients with a traditional prosthesis. All patients in the myoelectric prosthesis group demonstrated functional terminal grasp/release that they considered useful,” the researchers wrote.

Study authors include Sean R. Cantwell, M.D., Andrew W. Nelson, C.P.O., Brandon P. Sampson, C.P.O., Robert J. Spinner, M.D., Allen T. Bishop, M.D., Nicholas Pulos, M.D., and Alexander Y. Shin, M.D., Mayo Clinic, Rochester, Minnesota.