American Society for Peripheral Nerve

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Targeted Muscle Reinnervation in the Lower Extremity: A Technique for Prevention of Symptomatic Neuroma and Phantom Limb Pain at time of Below Knee Amputation
Chris Devulapalli, MD; Christopher E. Attinger, MD; Grant M Kleiber, MD
Georgetown University Hospital, Washington, DC

Amputation stump neuromas and/or phantom limb pain (NPLP) can be a devastating consequence of below knee amputation (BKA), with incidences reported up to 67%, often preventing the amputee from successful transition to prosthesis. The majority of symptomatic stump neuromas at our limb salvage center involve the superficial peroneal nerve (SPN) or saphenous nerve. Conventional treatment strategies, both surgical and medical, have failed to consistently show promise to treat and/or prevent NPLP. We provide a novel approach using combined targeted muscle reinnervation (TMR), common peroneal neuroplasty, and neurectomy of the tibial and saphenous nerve, at time of primary BKA for prevention of NPLP.

All procedures were performed at the time of primary BKA under tourniquet control. Neuroplasty of the common peroneal nerve (CPN) was performed using a 3 cm incision below the fibular head, releasing the compression point at the posterior crural intermuscular septum. For TMR, the SPN stump was identified in the distal amputation wound and withdrawn proximally into the incision over the CPN. Fascicular groups of the CPN were separated by internal neurolysis and a redundant motor branch to the anterior or lateral compartment was identified using a nerve stimulator. Antegrade coaptation of the SPN stump was performed to this recipient motor nerve. Finally, the saphenous and tibial nerve stumps were identified, crushed proximally to induce axonotmesis, and translocated proximally along the nerve sheath. All patients were followed postoperatively to assess for clinical parameters of wound healing, symptomatic neuroma, phantom limb pain, and successful transition to prosthesis.

Ten patients, age range from 29 to 81 years, underwent primary BKA and the aforementioned protocol. Mean operative time added to the BKA procedure for this was 27 minutes (22 to 31 minutes). TMR proceeded successfully in all 10 cases with coaptation of SPN nerve stump to a redundant motor branch of CPN (tibialis anterior in 2 cases, extensor digitorum longus in 5 cases, peroneus longus in 2 cases, and peroneus brevis in 1 case). During follow-up to 6 months, no patients showed signs of stump neuroma or phantom limb pain.

We present a novel treatment algorithm for possible prevention of symptomatic amputation stump neuroma and phantom limb pain with SPN TMR at time of primary BKA. We found this protocol to be safe, effective, and expedient. No patients showed signs of phantom limb pain or symptomatic stump neuroma postoperatively.

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