A Case of Fibula Regeneration after Below-the-knee Amputation in an Adult.

We report the case of an adult with fibula regeneration after below-the-knee amputation. Fibula regeneration conventionally occurs at the donor site of children after autogenous fibula transplantation when the periosteum is preserved. However, the patient was an adult, and the regenerated fibula was 7-cm long and grew directly from the stump. A 47-year-old man was referred to the plastic surgery department owing to stump pain. He had an open comminuted fracture of the right fibula and tibia due to a traffic accident when he was 44 years old and underwent below-the-knee amputation and negative pressure wound therapy for skin defects. The patient recovered and was able to walk using a prosthetic limb. Upon radiography, the fibula was found to have regenerated 7 cm directly from the stump. Pathological examination revealed that the regenerated fibula contained normal bone tissue and neurovascular bundles in the cortex. The periosteum, mechanical stimuli with limb proteases, and negative pressure wound therapy were suspected to have accelerated bone regeneration. He had no inhibitory factors for bone regeneration, including diabetes mellitus, peripheral arterial disease, or active smoking status. After the resection of the regenerated fibula, the patient was ambulatory without further bone regeneration or pain. This case report suggests that bone regeneration may occur even in adults. The surgeon should not leave any part of the periosteum behind in patients undergoing amputation. In adult amputees complaining of stump pain, the possibility of bone regeneration may be considered.