Free vascularized fibula leads to hallux toe flexion deformity due to ischemic muscle contracture of flexor hallucis longus.

[BACKGROUND] This study aimed to investigate the incidence of toe flexion deformity after fibular free flap transplantation and to analyze the etiology of the deformity.

[METHODS] Fifty patients underwent vascularized fibular free flap transplantation were retrospectively included. Statistical analysis examined correlations between deformity occurrence and resected fibula length and residual distal fibula length using the χ2 test. Doppler ultrasound and anatomical evaluations were conducted.

[RESULTS] Flexion deformity of the first toe was observed in all patients (100%), exacerbated by ankle dorsiflexion. χ test revealed no significant correlation between fibula length, distal residual fibula length, and flexion deformity. Doppler ultrasound revealed elevated echoes and blurred textures in the flexor hallucis longus post-fibular transplantation, while anatomical evaluation confirmed the peroneal artery as its primary nutrient supplier.

[CONCLUSION] This study reports a 100% incidence of toe flexion deformity post-transplantation. The deformity correlated strongly with ischemic contracture of the flexor hallucis longus.