Cross-Leg Free Anterolateral Thigh Flap with Indocyanine Green Angiography for the Reconstruction of Pediatric Vessel-Depleted Lower Limb Trauma Defect: A Salvage Strategy

Abstract Reconstruction of complex pediatric lower limb defects in the absence of suitable recipient vessels remains a significant microsurgical challenge. We report a case of a 10-year-old child presenting with an acute posttraumatic composite defect of the posteromedial foot and medial lower third of the leg associated with tibial and fibular fractures, heel pad avulsion, exposed calcaneal bone, and complete transection of the posterior tibial neurovascular bundle. Intraoperative exploration revealed severely compromised recipient vessels, precluding conventional ipsilateral free tissue transfer. A cross-leg free anterolateral thigh (ALT) flap harvested from the contralateral thigh was anastomosed end-to-end to the posterior tibial vessels of the nontraumatized limb. Primary nerve grafting of the posterior tibial nerve was performed using a 7-cm autologous nerve graft harvested from the nerve to vastus lateralis. Staged ischemic conditioning and indocyanine green (ICG) angiography were used prior to pedicle division. Limb salvage was achieved. At 12 months, the patient demonstrated independent full weight-bearing ambulation, radiographic fracture union, an AOFAS (American Orthopaedic Foot and Ankle Society) Ankle-Hindfoot Score of 81/100, and S3 sensory recovery in the reconstructed posterior tibial nerve territory. Cross-leg ALT free flap reconstruction with adjunctive ICG-guided perfusion assessment may provide a valuable salvage option in pediatric vessel-depleted lower limb trauma when conventional ipsilateral free tissue transfer is not feasible.