EXNER OSTEOTOMY AND EXCISION OF FIBULAR ANLAGE IN FIBULAR HEMIMELIA

Abstract

Fibular hemimelia is associated with equinovalgus deformity of the ankle and hind foot and antero-medial bowing of tibia. A wedge shaped distal epiphysis of the tibia and tight posterolateral soft tissues play an important role in the pathogenesis of ankle valgus and lateral subluxation of foot. Tethering effect of fibular anlage may contribute to the deformities in the tibia and ankle. Lengthening procedures are associated with progression of these deformities.

The purpose of this study is to determine whether Exner Osteotomy and Excision of Fibular anlage will correct the valgus deformity of the ankle and antero-medial bowing of tibia. A bending osteotomy through the distal tibial physis as described by Exner and excision of Fibular Anlage was performed in six limbs in five children (4 boys, 1 girl) with fibular hemimelia. Histology of Excised Fibular anlage was studied under light microscopy. The mean age at the time of surgery was twenty two months (range: 8 months to 5 years).

The mean follow-up was two years and two months (13 months to 4 years and 8 months). Full Correction of ankle valgus and tibial bowing was achieved in three feet where, a cortical strut graft was used in the open wedge osteotomy. In two feet synthetic bone substitute was used. In these, tibial bowing corrected but slight ankle valgus remained. In one foot where synthetic bone substitute was used and the postoperative compliance with AFO was poor, bowing of tibia improved but ankle valgus recurred. Premature fusion of growth plate did not occur in any of the cases. Histology of fibular anlage showed replacement of bone tissue by mature collagen bundles surrounded by fibroconnective tissue.

Exner Osteotomy and Excision of Fibular Anlage in Fibular Hemimelia corrects the ankle valgus and antero-medial bowing of tibia.