Analysis of Functional Outcomes and Donor Site Morbidity Following Fibula Flap Harvest in the Skeletally Immature Patient Population

BACKGROUND: Free fibula flaps have been widely used for bony reconstruction in pediatric patients. While donor site complications have been well studied in adults, data in the pediatric population remains limited. This study exclusively reports donor-site morbidity following fibula flap harvests in the pediatric and adolescent population. METHODS: We reviewed all patients younger than 18 years with open physes who underwent fibula flap harvests at a single academic institution from 1997 to 2024. Demographics, clinical and surgical characteristics, and donor-site complications were recorded. RESULTS: Fifty-seven free fibula flaps were harvested from 55 pediatric patients (mean age 12 years; 29 female) with a mean follow-up of 6 years. Flaps were most commonly used for lower extremity reconstruction (52%) and following tumor resection (74%). Osteoarticular flaps (n=8) were associated with transient deep peroneal nerve palsy in four cases, all of which recovered antigravity dorsiflexion by 6 months. In standard segmental harvests (n=49), donor-site complications occurred in 38%, most frequently valgus ankle deformity (9%) and neuropathic pain (6%). Valgus deformity was more likely in patients with shorter distal residual fibula and an age-residual fibula index (A-RFI) <16. CONCLUSIONS: Vascularized fibula flaps are safe and versatile for pediatric skeletal reconstruction. Donor-site complications are common but generally manageable, with full recovery of nerve function. Osteoarticular harvests carry the highest risk of peroneal nerve injury, and valgus ankle deformity may occur, particularly with an age-residual fibula index <16. Careful planning and age-adjusted fibular preservation are essential to optimize outcomes.