Impact of Fixation Methods on Long-Term Bone Graft Hypertrophy in Free Fibular Flap Transfer: Analysis of 51 Lower-Limb Reconstructions

BACKGROUND: In lower-limb reconstruction using free fibular flaps, fibular hypertrophy is essential for achieving weight-bearing function. However, the effects of different fixation methods on hypertrophy and its long-term progression remain unclear. METHODS: We retrospectively reviewed 51 patients who underwent free fibular flap transfer to the femur or tibia between 2003 and 2024. Fixation methods included external skeletal fixator (ESF), dynamic compression plate (DCP), locking compression plate (LCP), and others. Hypertrophy was evaluated as the ratio of fibular width on follow-up radiographs to that on the immediate postoperative radiograph. Long-term changes were assessed in patients with ≥2-year follow-up radiographs. RESULTS: ESF was used in 12, DCP in 28, LCP in 6, and others in 5 patients. Recipient sites were femur in 12 and tibia in 39 patients. At the last follow-up (mean 5.7 years), mean hypertrophy ratios were 1.08 (ESF), 1.48 (DCP), 1.69 (LCP), and 1.20 (others), with LCP showing the highest value. Multivariable mixed-effects linear regression analysis identified DCP as being significantly associated with greater hypertrophy compared with ESF (p = 0.011). Younger age was also significantly associated with greater hypertrophy. In 30 patients with ≥2 years of follow-up, hypertrophy progressed significantly beyond 2 years, with a greater increase in patients younger than 20 years. CONCLUSIONS: Plate fixation, particularly using LCPs, may represent an optimal fixation method for promoting hypertrophy. The continued progression of hypertrophy beyond 2 years, especially in younger patients, highlights the potential advantages of fibular flap transfer in pediatric lower-limb reconstruction.Level of Evidence: 3.