Clubfoot deformity has four components: cavus, forefoot adductus, hindfoot varus, and equinus (Figure 1). Patients should be thoroughly examined for underlying etiologies, especially neurologic or muscular disorders.

In a patient with idiopathic clubfoot, it is not necessary to obtain radiographs of the feet before proceeding with casting. Forced dorsiflexion lateral images may be helpful later in the casting process, immediately before deciding whether or not percutaneous Achilles tenotomy is necessary (Figure 2).

Talipes equinovarus may be identified on prenatal ultrasonography as early as gestational week 12, although the false-positive rate is approximately 20%. More than 50% of infants with prenatally identified clubfoot are born with associated anomalies, primarily neurologic, cardiac, or other musculoskeletal disorders.⁵

First, the foot is stretched. One hand is used to abduct the foot (the right hand for the right foot, the left hand for the left foot), with the index finger placed along the medial aspect of the foot and the third, fourth, and fifth fingers supporting the plantar aspect of the foot. The contralateral hand is placed with the index finger behind the lateral malleolus and the thumb over the lateral head of the talus. Care is taken not to apply counterpressure over the lateral portion of the calcaneus because this will prevent correction of the deformity through the subtalar joint, the key to Ponseti⁶ correction. For the first casting, the first ray should be elevated to correct the cavus deformity. During all subsequent sessions, the first ray should remain elevated, keeping all the metatarsals aligned. This will prevent regeneration of the cavus deformity and rotation of the talus under the tibia as the foot is abducted.

After the foot has been stretched, a cast is applied to maintain the foot in the position of maximum stretch without overstretching. Starting at the toes, the lower leg is wrapped with two or three layers of cotton padding over the fingers of the practitioner who is holding the toes. Plaster is applied in two or three layers while the foot is held in the same manner as during stretching (supporting the foot against counterpressure over the lateral head of the talus, although persistent pressure should be avoided so as to not cause pressure sores). With the foot held with an abduction moment across the talar head, the cast is meticulously molded around the malleoli and posteriorly above the calcaneus.

The short leg cast is then extended into a long leg cast, up to the groin, with the knee flexed at 90°. In larger or stronger children, an anterior splint of four layers of plaster is applied over the knee during circumferential casting to provide additional strength but minimize bulk in the popliteus fossa.

Cast material should be trimmed away from around the toes dorsally and along both sides, leaving a plate under the toes, to allow full dorsiflexion but maintain stretch of the toe flexors. The dorsal edge should not be trimmed proximal to the web space of the toes because a tourniquet effect may occur, inducing swelling of the foot.

For complex and teratologic clubfeet, a posterior splint may be applied behind the lower leg and under the foot during casting, and the knee should be flexed 110° to 120° to prevent pulling back in the cast.⁷

Casts are changed weekly, although more frequent changes are possible.⁸ Typically, four to six casts are required to achieve full correction.

Once the foot has reached 60° to 70° of abduction relative to the sagittal plane and if there is less than 15° of dorsiflexion, a percutaneous Achilles tenotomy is performed to correct the remaining equinus deformity. The final cast is applied with the foot in the position of maximum dorsiflexion obtained following the tenotomy and maximum abduction. If the practitioner believes the foot is adequately corrected and may not need a tenotomy, a lateral radiograph
of the foot in maximum dorsiflexion should be obtained; 15° of dorsiflexion should be present without midfoot breach (Figure 2).