The purpose of the manipulation and casting is to correct the first three aspects of clubfoot as described by the acronym CAVE. (Cavus, Adductus, Varus and Equines). The correction is carried out in the same sequence as in the acronym CAVE. Cavus, Adductus and Varus are corrected first with manipulation and casting. Equines are corrected with a tenotomy. Treatment intends to correct these four deformities gradually and sequentially.
Let us explain each one of these deformities in a clubfoot.
Cavus: In clubfoot, the forefoot is bent downward creating the shape of a cave. The foot looks like a cave. This deformity is corrected first by supination, with the talar head as the fulcrum the great toe (first ray) is raised with the middle finger. So after applying the first plaster cast, the clubfoot foot may appear worse than how it looked before the cast. This manipulation is done intentionally to correct the cavus.
Adductus: In a clubfoot, the foot is bent inward. The front of the foot (forefoot) turns inward bringing all the toes closer to the sole and heal. ‘Adduction’ is bending inward and the opposite term ‘abduction’ is bending outward or external rotation. The adductus is corrected by manipulating and stretching the foot externally. The middle finger again raises the great toe (first ray) and the pointer finger externally rotates (abducts the foot). Remember the fulcrum remains the head of the talus.
Varus: The bone we feel in the heel, is called calcaneus. This bone is in the wrong position clubfoot and it is called Varus. So in clubfoot when we touch the heel, we do not feel the bone – the calcaneus. When cavus and adductus are corrected by supination and abduction respectively, the varus comes to the valgus position automatically. This happens because the movement of one bone affects the position of other bones in the foot and this natural mechanism is called kinematic coupling. Varus is not corrected by any effort in the Ponseti method but is automatically corrected as the other bones come into alignment.
Equines: In clubfoot, the tendon in the back of the foot is short (very visible in unilateral clubfoot) and if not treated the weight of walking goes to the toes. This is called Equines and is corrected by a procedure called tenotomy. Tenotomy is the cutting of the tendon. The tendon is cut with local anaesthesia and the cut is so small a stitch is not required. The tendon that is cut regenerates naturally in 3 weeks. In postural clubfoot, the equines requires no correction so a tenotomy is not given to those children with postural clubfoot.
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