Sciatic nerve: paradoxic hypertrophy after amputation in young patients.

Abstract

To evaluate the appearance of the sciatic nerve after leg amputation. Magnetic resonance (MR) images were obtained in seven patients (age at amputation, 11-19 years) who underwent above-knee amputation to treat osteogenic sarcoma. Images were evaluated for sciatic nerve enlargement. Findings were correlated with the time after amputation. All seven patients were found to have a markedly enlarged sciatic nerve in the stump of the amputated leg. The enlargement extended proximally from the point of nerve transection to a level posterior to the femoral neck (8-27 cm) depending on the length of the stump. No evidence of sciatic nerve enlargement was found in the opposite leg or on preoperative MR images that were available in three of the patients. Moreover, in one patient with a sarcoma who underwent a leg-sparing procedure, no sciatic nerve enlargement was seen postoperatively. The thickness of the distal sciatic nerve was related to the time after amputation. Hypertrophy of the sciatic nerve occurred after above-knee amputation in young patients. This finding differed from atrophy of the nerve that has been reported previously in older patients.