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Physician Resource

Targeted Muscle Reinnervation Improves Functionality After Upper Limb Amputation

Amputation of any part of the upper extremities typically represents a substantial threat to a patient’s functional abilities and quality of life. Traditional prosthetics, while helpful, are static, or fixed: A patient may be able to manipulate the prosthesis to perform some activities of daily living, but its performance pales in comparison to the patient’s natural limb.

Myoelectric prostheses are a significant improvement over conventional hand and arm prosthetics. Targeted muscle reinnervation (TMR) allows the patient greater control of an upper extremity prosthetic. Past procedures often sacrificed one or several nerves, leading to complications like phantom limb pain as a result of neuroma formation.

Now, orthopedic and plastic hand surgery specialists at UVA Health offer a new TMR technique that preserves nerve endings to help drive upper extremity prosthetics, giving patients more intuitive functional control over a myoelectric prosthetic.

Together with other experts from UVA Health orthopedics and plastic hand surgery and UVA Health prosthetics, Department of Orthopaedics chair Bobby Chhabra, MD, and associate professor of plastic surgery Brent DeGeorge, MD, PhD, detail how this new technique helped one patient regain functionality by pushing the boundaries of nerve regeneration and recovery.

Case Study: Table Saw Traumatic Injury Benefits From TMR

In most cases, upper extremity amputations result from traumatic injuries. That was the case with a former UVA Health physician, who sustained substantial injuries to his hand while using a table saw.

Chhabra explains, “This patient was experienced with using tools like a table saw, but unfortunately, something in the saw got stuck, and he ended up having a pretty severe amputation of his entire hand. The saw came through his hand and forearm in multiple locations — the injury included his bones, soft tissues, nerves, and blood vessels. While we attempted to save his hand so he could retain function, it wasn’t possible given the severity of the injury.”

Ultimately, the surgical team performed a transradial amputation, removing both the wrist and hand and providing stable, soft tissue coverage for the resulting amputation stump. While healing, the patient expressed a desire for a prosthetic that would offer greater finger dexterity and more natural hand movements. Such a prosthetic would also provide better management of residual, or phantom, limb pain.

After the initial surgery and subsequent recovery period, both DeGeorge and senior prosthetist Alex Ashoff, CP, MSPO, were consulted to help the patient manage the new amputation. After orthopedic hand surgery management, plastic hand surgery specialist DeGeorge got involved to help manage soft tissue and nerve-related pain. DeGeorge says, “I work extremely closely with the orthopedic surgeons. We want to give challenging patients like this the best chance for functional recovery.”

TMR Technique Better Manages Nerves

In the past, the median, radial, and ulnar nerves were typically sacrificed when a hand or upper extremity was amputated. These nerves would be cut and their endings placed under the skin, with the hope that neuromas wouldn’t form and become painful and symptomatic.

DeGeorge explains, “Now, we reroute the nerves to new muscle targets. This results in new nerve signals that can be used to help drive prosthetics, giving patients more intuitive functional control over a myoelectric prosthesis. We also found that this approach helps minimize phantom limb pain. This is a truly innovative procedure at UVA Health that helps manage many nerve-related problems.”

Following the procedure, Ashoff was brought on to fit the new prosthetic and teach the patient how to use it. He says, “This patient was highly motivated to use this type of [myoelectric] device. They can be cumbersome, and the patient rejection rate can be high. However, this type of prosthesis picks up the muscle signal topically on the arm when the patient thinks about flexing or opening his wrist. That sends a signal to the prosthetic to either open or close the hand.”

Prosthetic Provides Greater Grip Control

The patient can push a button on the prosthetic to switch between different grips; different-sized and shaped objects require different grips. The patient now has the ability to change grips to complete any task, from gripping a fork to holding onto bicycle handlebars. See the prosthetic in action.

Ashoff says, “It’s really important that the patient is compliant with their therapy — PT and OT — so that they can master using the device every day. Patients also come back to see me so that we can optimize their prosthetic and make any necessary adjustments.”

Thanks to the specialists’ collaborative efforts, the patient is learning to use his prothesis for daily tasks. “This particular patient had a lot of goals related to really precise grip patterns — think of a pinch grip and being able to handle small objects for different household activities of daily living. Already, the prosthetic makes frequent travel possible, and the patient can interact with family and grandchildren normally,” says Ashoff.

Advancing Nerve Repair With Electrical Stimulation

UVA Health continues to push the boundaries of nerve regeneration and recovery by incorporating electrical stimulation as a component of nerve repair.

DeGeorge notes, "There’s new evidence that low-grade electrical stimulation of peripheral nerves can enhance repair and the muscle regeneration process.”

“While we didn’t use these techniques with this patient, we are trialing them with others. It’s another example of how UVA Health is on the cutting edge of medicine that helps patients recover better.”

Chhabra agrees, “TMR surgery, it’s not just for traumatic injuries. We hope to develop the program for people with amputations related to vascular problems or diabetes. We also want to better serve patients with significant pain issues so we can help improve their quality of life.”

Referral Center for Difficult Nerve-Related Problems

Results like these wouldn’t be possible without the team approach UVA Health experts take toward managing injuries of this type. The collaborative effort between specialty teams in a single location allows physicians to provide truly advanced care for this specific patient population. Patients see multiple providers during the same visit at the UVA Health Orthopedic Center Ivy Road, which helps the entire team develop a treatment plan for the best outcomes possible.

Chhabra says, “I want other physicians to know that we’re a center that wants to see these patients; in many cases, they’re not given many options, or they mistakenly believe they have to live with a decreased quality of life. That simply isn’t true. We’re one of a very few facilities in Virginia offering these new TMR techniques. The program is ideal in that it shows the collaborative effort across disciplinary teams. It also shows how innovative UVA Health is in terms of caring for difficult, complex medical problems.”

“This is for a lot of people. If patients have difficult-to-treat nerve-related problems, we’re here. We’re available and willing and excited to see these patients. We offer additional options that are not just narcotics,” agrees DeGeorge.

UVA Health is focused on providing the most advanced care for amputees. Many patients and providers are unaware of new surgical techniques and innovations that can help this patient population thrive. These new tools, coupled with the UVA Health interdisciplinary approach to patient care, mean patients with devastating injuries have hope for recovery.

Chhabra says, “Other facilities in the state aren’t doing this, particularly for upper limb prosthetics. Having prosthetics that are this functional — as close to the human hand as possible — is a huge advance. It wouldn’t be possible without TMR and the work of all our specialists.”

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