MRI pathoanatomy study of congenital vertical talus.

Background: Prior reports regarding the pathologic anatomy for congenital vertical talus have noted some disagreement as to which elements of the pathologic anatomy are consistently present. The purpose of his study is to evaluate the 3-dimensional morphologic changes and pathoanatomy of the congenital vertical talus using magnetic resonance imaging.

Methods: Nine patients with congenital vertical talus (ranging from 5 mo-11 y) underwent magnetic resonance imaging of both feet. A foot and ankle coil was used for the 1.5 T system. The protocol consisted of T1-weighted spin echo sequence image and T2-weighted fast spin echo sequence image in the sagittal, coronal, and axial planes. Slice thickness ranged from 3 to 4 mm with 0 to 1.0 mm interspace thickness. A descriptive analysis was performed based upon the T1-weighted image by physicians.

Results: At the level of the talonavicular joint, the navicular was seen significantly subluxed dorsally with associated wedging of the navicular. At the level of the calcaneocuboid joint, often there was a significant dorsal subluxation of the cuboid in relation to the calcaneus. Lateral obliquity of the calcaneocuboid joint could be present to varying degrees. The anterior calcaneus was significantly laterally displaced in relation to the talar head with an element of lateral translation and eversion of the calcaneus at the subtalar joint. Distal cavus at the cuneiform-first metatarsal joint was observed in 5 patients.

Conclusions: This study suggests that there is significant pathology at the level of subtalar joint in congenital vertical talus. In addition to satisfactory reduction of the talonavicular joint, methods to ensure realignment of the calcaneus under the talus may be a crucial component of deformity correction and to prevent recurrence of deformity.

Level Of Evidence: A Level III diagnostic study using normal pediatric foot anatomy in magnetic resonance imaging as a reference.