Pre-axial mirror polydactyly associated with tibial deficiency: a study of the patterns of skeletal anomalies of the foot and leg

Abstract

Purpose: The study was undertaken to identify the patterns and spectrum of aberrant development of the skeletal elements of the leg and foot in children with pre-axial mirror polydactyly of the foot.

Methods: Case records and radiographs of eight children (ten feet) with pre-axial mirror polydactyly were studied. Four feet were seen in association with fibular dimelia, three feet with dysplastic trapezoid shaped tibia, two with tibial aplasia and one with tibial hypoplasia.

Results: Distinct patterns of anomalies of the hindfoot, midfoot and forefoot were noted, with different patterns of leg malformation. Fibular dimelia was associated with duplication of the calcaneum, cuboid and the lateral cuneiform. Talar duplication occurred in children with a trapezoidal tibia. No duplication of tarsal bones was seen in association with tibial aplasia or hypoplasia. The first metatarsal was hypoplastic wherever the tibia failed to develop. Mere resection of the supernumerary rays resulted in a near normal looking foot in feet without calcaneal duplication. The cosmetic appearance of the foot was poorest in children with fibular dimelia.

Fig. 1

a Radiograph of the lower limbs of a child with pre-axial mirror polydactyly, showing bilateral fibular dimelia with tibial aplasia. b Radiograph of the lower limbs of a child with pre-axial mirror polydactyly, showing bilateral absence of tibia without duplication of the fibula. c Radiograph of the leg of a child with pre-axial mirror polydactyly, showing a short broad dysplastic trapezoidal tibia. d Radiograph of the leg of a child with pre-axial mirror polydactyly, showing a short bowed hypoplastic tibia

Fig. 2

Clinical photograph of a child with pre-axial mirror polydactyly. Severe equinovarus deformity, mirror duplication of the toes and a normal-looking heel are seen. The child had tibial aplasia without fibular duplication

Fig. 3

a Radiograph of the hind foot of a child with tibial aplasia, showing a single talus and a single calcaneum. b Radiograph of the hind foot of a child with a dysplastic trapezoidal tibia, showing duplication of talus and a single calcaneum. c Radiograph of the foot of a child with fibular dimelia, showing a single talus with duplication of the calcaneum, cuboid and lateral cuneiforms. The first metatarsal is hypoplastic

Fig. 4

a Initial radiograph of the foot of a child with fibular dimelia, showing the bones of the hind foot. The appearance was suggestive of talar duplication with a single calcaneum. b Follow-up radiograph of the foot of the same child shows a single talus and duplication of the calcaneum. A well-formed cuboid articulates with each calcaneum, and the calcanea are now of almost the same size

Fig. 5

Post-operative clinical photograph of the foot of the patient with tibial hypoplasia, showing a plantigrade foot with a normal-looking heel

Fig. 6

Appearance of pre-axial mirror polydactyly with fibular dimelia. The double heel is clearly seen