Incidence and Nerve Distribution of Symptomatic Neuromas and Phantom Limb Pain After Below-Knee Amputation
Brian L Chang, MD1, Josh Mondshine, BS1, Christopher E. Attinger, MD2 and Grant M. Kleiber, MD3, (1)Georgetown University, Washington, DC, (2)Plastic Surgery, MedStar Georgetown University Hospital, Washington, DC, (3)Medstar Georgetown University Hospital, Washington, DC
Introduction
Patients with major lower limb amputations suffer from symptomatic neuromas and phantom-limb pain as a result of their transected nerves. Peripheral nerve surgery techniques like targeted muscle reinnervation (TMR) and regenerative peripheral nerve interface (RPNI) aim to physiologically prevent this nerve-specific pain. No studies have specifically reported on which nerves most frequently cause chronic pain. The purpose of this study is to determine the nerve-specific incidence of symptomatic neuroma formation and phantom limb pain in patients undergoing a below-the-knee amputation. This knowledge will allow for better tailored use of TMR and RPNI.
Materials and Methods
This is a retrospective review of all patients undergoing a below-the-knee amputation (BKA) from 1/1/2013 to 12/31/2018. All BKAs were performed with a posterior skin flap, myotenodesis, and traction neurectomies of all identified nerves. Post-operative notes were reviewed for the presence of a symptomatic neuroma, defined as localized pain and a Tinel over a known sensory nerve, and nerve-specific phantom limb pain, defined as pain of the missing limb corresponding to a known dermatome.
Results
198 patients were included in this study. Overall rates of residual limb pain and phantom limb pain were 57.1% and 44.9%, respectively. The rate of symptomatic neuroma formation was 14.6% (29/198). Of patients with symptomatic neuromas, the superficial peroneal nerve was involved in 89.7% of patients, saphenous nerve in 48.3%, tibial nerve in 17.2%, sural nerve in 17.2%, and deep peroneal nerve in 0% of patients. Diabetes and obesity were protective against symptomatic neuroma formation. The rate of nerve-specific PLP was 12.6% (25/198) and highly correlated with the presence of a symptomatic neuroma.
Conclusions
To optimize outcomes for amputees, it is critical that one best understands what nerves are more likely to form symptomatic neuromas and lead to nerve-specific phantom limb pain so that one can best tailor primary or secondary management of the major sensory nerves.
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