Incidence and Nerve Distribution of Symptomatic Neuromas and Phantom Limb Pain after Below-Knee Amputation

Patients with major lower limb amputations suffer from symptomatic neuromas and phantom-limb pain due to their transected nerves. Peripheral nerve surgery techniques, such as targeted muscle reinnervation and regenerative peripheral nerve interface, aim to physiologically prevent this nerve-specific pain. No studies have specifically reported on which nerves most frequently cause chronic pain. The authors studied the nerve-specific incidence of symptomatic neuroma formation and phantom limb pain in patients undergoing a below-knee amputation, to better tailor use of targeted muscle reinnervation and regenerative peripheral nerve interface.This was a retrospective review of all patients undergoing a below-knee amputation from January 1, 2013, to December 31, 2018, at MedStar Georgetown University Hospital. All below-knee amputations were performed with a posterior skin flap, myotenodesis, and traction neurectomies of all nerves. Postoperative notes were reviewed for the presence of a symptomatic neuroma, defined as localized pain and a Tinel sign over a known sensory nerve, and nerve-specific phantom limb pain, defined as pain of the missing limb corresponding to a known dermatome.One hundred ninety-eight patients were included in this study. The rate of symptomatic neuroma formation was 14.6 percent (29 of 198), with the superficial peroneal and saphenous nerves most often involved. Diabetes and obesity were protective against symptomatic neuroma formation. The rate of nerve-specific phantom limb pain was 12.6 percent (25 of 198) and highly correlated with the presence of a symptomatic neuroma.To optimize outcomes for amputees, it is critical that surgeons best understand what nerves are more likely to form symptomatic neuromas and lead to nerve-specific phantom limb pain, so that surgeons can best tailor primary or secondary management of the major sensory nerves.Risk, III.