Clubfoot Workup

Updated: Apr 17, 2017
  • Author: Minoo Patel, MBBS, PhD, MS, FRACS; Chief Editor: Vinod K Panchbhavi, MD, FACS  more...
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Workup

Imaging Studies

Imaging studies generally are not required to understand the nature or the severity of the deformity. Radiography, however, provides a useful baseline before and after surgical correction of the feet, closed Achilles tenotomy, or a limited posterior release. Radiographs show the true gain in foot (ankle) dorsiflexion and confirm the appearance of an iatrogenic rockerbottom foot should one result. Occasionally, radiographs are necessary to diagnose clubfeet associated with tibial hemimelias.

Radiography

Talocalcaneal parallelism is the radiographic feature of clubfeet. Simulated weightbearing x-rays are used for infants who have not commenced walking. Positioning for foot x-rays is very important. The anteroposterior (AP) view is taken with the foot in 30° of plantarflexion and the tube at 30° from vertical. The lateral view is taken with the foot in 30° of plantarflexion.

AP and lateral views also can be taken in full dorsiflexion and plantarflexion. This is especially important in measuring the total amount of dorsiflexion achieved at the end of treatment, as well as the relative positions of the talus and calcaneum.

Measure the talocalcaneal angle in the AP and lateral films. AP lines are drawn through the center of the long axis of the talus (parallel to the medial border) and through the long axis of the calcaneum (parallel to the lateral border), and they usually subtend an angle of 25-40°. Any angle less than 20° is considered abnormal.

The AP talocalcaneal lines are almost parallel in clubfeet. As the feet correct with casting or surgery, the calcaneus rotates externally, and the talus reciprocally also derotates to a lesser degree to give a convergent talocalcaneal angle.

Lateral lines are drawn through the midpoint of the head and body of the talus and along the bottom of the calcaneum, usually 35-50°. Clubfoot ranges between 35° and negative 10°.

The lateral talocalcaneal lines are almost parallel in clubfeet. As the feet correct with casting or surgery, the calcaneum dorsiflexes relative to the talus to give a convergent talocalcaneal angle.

These two angles, AP and lateral, are added to derive the talocalcaneal index, which in a corrected foot should be more than 40°.

The AP and lateral talar lines normally pass through the center of the navicular and the first metatarsal.

In older children, a flat-top talus can be demonstrated radiologically if the talus is sufficiently calcified, but care is required for positioning of the foot.

A lateral film with the foot held in maximal dorsiflexion is the most reliable method of diagnosing an uncorrected clubfoot; the absence of calcaneal dorsiflexion is evidence that the calcaneus is still locked in varus angulation under the talus.