A 35-yr-old man was seen on a routine follow-up visit after left-sided transtibial amputation because of a landmine injury 19 yrs ago. He complained of throbbing pain on the lateral side of the distal stump as he used his prosthesis (modular type with a silicone liner with shuttlelock). The rest of the medical history was unremarkable. On physical examination, the stump was clean and normal (11 cm in length starting from the inferior pole of the patella), but palpation of the lateral side caused severe pain. Allodynia was present, Visual Analog Scale and Leeds Assessment of Neuropathic Symptoms and Signs scores were 6 and 17, respectively. Ultrasonographic imaging was performed to evaluate the stump and the distal ends of the major nerves. A neuroma on the common peroneal nerve and a bony spur on the tibia were detected (Fig. 1A). Knee x-ray also confirmed the bony spur (Fig. 1B). Accordingly, surgical excision of the neuroma and the spur was performed.
Because there is no distal tunnel for nerve growth after amputation, a disorganized, pseudotumor-like, growth of Schwann cells and a tangle of misled sprouting axons are well known to form bulbous-shaped neuromas in the peripheral nerves.1,2 It may sometimes be quite challenging to differentiate stump pain associated with a neuroma from symptoms related to infection, inflammation, vascular insufficiency, bone sequestration, heterotopic bone formation, foreign substances, hematomas, and atrophic stump muscles.3 In our case, during initial sonographic evaluations of the painful stump, we have interestingly observed a small bony spur in very close relation to the common peroneal nerve. Furthermore, the spur being immediately proximal to the neuroma formation and indenting the nerve trunk (similar to an entrapment scenario) was also noteworthy. Peroneal neuromas or bony entrapment of the peroneal nerve during fracture healing have been mentioned before4; however, to the best knowledge of the authors, peroneal neuroma in association with a bony spur after amputation has not been commonly reported. We advise that prompt shaving of the bony surfaces is crucial during amputation surgery as far as the long-term consequences, including those of the peripheral nerves, are concerned. Herewith, sonography seems to be a convenient and worthwhile tool for imaging of peripheral nerves during the follow-up of amputee patients.
1. Provost N, Bonaldi VM, Sarazin L, et al: Amputation stump neuroma: Ultrasound features. J Clin Ultrasound
2. Gruber H, Glodny B, Bendix N, et al: High-resolution ultrasound of peripheral neurogenic tumors. Eur Radiol
3. Kerimoglu U, Canyigit M: Paradoxic hypertrophy of the sciatic nerve in adult patients after above-knee amputation. Acta Radiol
4. Mino DE, Hughes EC Jr: Bony entrapment of the superficial peroneal nerve. Clin Orthop Relat Res