Paediatric Imaging

Calcaneonavicular coalition

congenital fusion between the calcaneus and navicular. This is one of the two commonest forms of tarsal coalition. Not all cases are symptomatic, but those that do present with symptoms usually do so during the second decade of life when the coalition ossifies, the child then developing pes planus and peroneal spasm. The diagnosis is generally suggested on a 45 oblique radiograph (Fig.1) which shows an anterosuperior extension from the calcaneus ("anteater-nose sign"). A lateral radiograph may show an anterodorsal extension from the talus (talar beak) as a secondary sign reflecting compensatory increased movement at the talonavicular joint. The coalition is better demonstrated on axial CT (Fig.2) or MR imaging which may show an osseus union or a narrowed calcaneonavicular joint with indistinct articular margins suggesting a fibrous coalition. There may also be associated hypoplasia of the talar head.

GL

To view high resolution images,
please register first.

Click  here to register.

Already registered? Enter your e-mail in the window below.
Re-register

Fig.1

Oblique view of the foot demonstrating incomplete calcaneonavicular coalition. Note anterior superior extension of the calcaneus ("anteater" nose) and approximation of the calcaneus and navicular.
Calcaneonavicular coalition, Fig.1
Calcaneonavicular coalition, Fig.2