Paradoxic hypertrophy of the sciatic nerve in adult patients after above-knee amputation.

Paradoxic hypertrophy of nerve tissue at an amputation stump without neuroma formation rarely develops in young patients, in contrast to atrophy of the nerve in older patients. Herein, we present the magnetic resonance imaging (MRI) findings of adult patients (older than 20 years old) who underwent above-knee amputation, one of whom had a palpable mass suggesting a recurrent lesion. MRI ruled out the recurrent lesion and demonstrated paradoxic hypertrophy of the sciatic nerve in all patients.