Evaluation of pathologic abnormalities of clubfoot by magnetic resonance imaging.

Three-dimensional analyses of clubfoot in infants younger than 1 year of age were done using magnetic resonance imaging in an in vivo study. Twenty-one patients (31 feet) with congenital clubfoot were examined. The average age at examination was 8.6 months (range, 4-12 months). All patients originally were treated using corrective casts. Seventeen feet required complete subtalar release operations and the remaining 14 feet were treated conservatively with various orthoses. Four measurements using magnetic resonance imaging were performed in the transverse and coronal planes as follows: the calcaneus adduction angle, to define the degree of medial rotation of the calcaneus in the transverse plane; the navicular angle, to define the degree of medial displacement of the navicular; the talus neck angle, to define the degree of medial angulation of the talus; and the calcaneus shift index, to define the degree of medial shift of the calcaneus beneath the talar head in the coronal plane. In the results, all four measurements of clubfoot on magnetic resonance imaging were statistically different from those of normal feet. In the surgical group there were statistical differences in the calcaneus adduction angle, the navicular angle, and the calcaneus shift index (including two feet of patients whose parents had rejected proposed treatment), compared with the conservative group, but there was no statistical difference in the talus neck angle. Magnetic resonance imaging could delineate the three-dimensional abnormalities of the tarsal bones in clubfoot and quantitatively evaluate the severity of clubfoot.