Valgus ankle deformity after vascularized fibular reconstruction for oncologic disease.

Abstract

Previous studies highlight the risk of valgus ankle instability in children following vascularized fibular procedures. We have observed that persistent valgus instability results in valgus deformity in these ankles. The aim of this study was to explore the risk factors associated with valgus ankle deformity following vascularized fibular graft harvest. We present 31 patients with minimum follow-up of 2 years and maximum of 18 years. They underwent regular clinical evaluation of their ankles and routine radiological evaluation when valgus deformity became clinically apparent. Five patients developed valgus ankle deformities. Risk factors for development of valgus deformity included age under 14 years (P = 0.02) and short [6 +/- standard deviation (SD) 1 cm] residual fibular lengths (P = 0.02). Age-residual fibula index (age in years plus residual distal fibula length in centimeters) under 16 strongly predicted the development of ankle deformity (P = 0.0008). Short residual fibular lengths were not consistently associated with valgus deformity. Children developed focal lateral tibial epiphyseal atrophy and premature antero-medial fusion of the distal fibular physis resulting in a concave-anterior bowing of the fibula. Skeletally mature patients had congruent joints and posterior rotation of the proximal fibula without bowing. Mechanical causes cannot solely explain valgus ankle deformity following vascularized fibula harvest. Secondary changes due to growth arrest in the ankle significantly contribute to this deformity.