Extensive ossification of the Achilles tendon with fracture treated by autologous peroneus longus tendon graft: a case report

BACKGROUND: Extensive ossification of the Achilles tendon (EOAT) is a rare condition, often associated with previous trauma or surgery. Cases complicated by fracture are even less common, and the optimal surgical approach remains a subject of discussion. CASE PRESENTATION: We report a 65-year-old male with a recent ankle sprain and a history of prior trauma to the same area over a decade ago. Imaging revealed an 85.6 mm long ossified mass within the Achilles tendon, which had fractured. The patient underwent surgical excision of the ossified mass and reconstruction using an autologous peroneus longus tendon graft with full restoration of ankle motion and function at 6 months. CONCLUSION: This case demonstrates a successful application of the peroneus longus tendon for reconstruction after Achilles tendon ossification with fracture. To our knowledge, this is the first reported case using a peroneus longus tendon graft for Achilles tendon ossification with fracture.