The spectrum of preaxial polydactyly of the foot

Polydactyly is a common congenital anomaly of the foot classified as preaxial, central, or postaxial depending on the location of the duplication. Approximately 15% of all duplications of the toes are preaxial. The purpose of this study is to report our experience in the management of preaxial polydactyly of the foot over a period of 30 years at a single institution.

This is a retrospective institutional review board-approved descriptive case series of 21 children representing 28 feet with preaxial foot polydactyly seen at our institution from 1977 to 2009. All subjects were analyzed in terms of sex, laterality, anatomic patterns of polydactyly, associated anomalies, family history, clinical features, surgical indications, details of surgical procedures, and outcomes after surgical interventions, using data collected from medical records, radiographs, and clinical photographs. Clinical outcomes were evaluated at the most recent examination, according to the format published by Phelps and Grogan.

There were 21 patients (28 feet) including 11 male and 10 female subjects. Duplications were bilateral in 7 patients and unilateral in 14. The average age at surgery was 1.8 years (range: 0.8 to 4.6 y). The average follow-up was 81.7 months (range: 5 to 180 mo). According to the Watanabey classification, the distal phalangeal type occurred in 4 feet, the proximal phalangeal type in 10 feet, the metatarsal type in 10 feet, the tarsal type in 2 feet, a combined tarsal and metatarsal type in 1 foot, and a mirror type in 1 foot. All patients had associated anomalies in the affected feet. Congenital hallux varus was the most common associated anomaly (20 feet). A longitudinal epiphyseal bracket was observed in 4 feet. Clinical outcomes after the initial surgery were excellent in 8 feet, good in 15 feet, and poor in 5 feet. The 5 feet rated as poor were because of residual deformities and required additional surgery. Good results were subsequently obtained at final follow-up in all 5 feet.

In our opinion, the Watanabe classification is more useful than the Venn-Watson for surgical planning. However, we have added an additional type, representing a mirror foot which we feel is within the overall spectrum of preaxial polydactyly. Good or better results were obtained in all feet at final follow-up. Early detection and adequate excision of the longitudinal bracket affecting the phalanges or metatarsal can reduce residual deformity and the need for revision surgery.