Clubfoot and congenital limb anomalies: SAQ

This child has the classic presentation of the idiopathic clubfoot, and the task is to outline the four classical deformities, the Ponseti method, the percutaneous tenotomy and the foot-abduction brace, the relapse and its management, and the broader family of the congenital limb anomalies. [1][5]

Question 1 (10 marks)

Outline the four classical deformities of clubfoot, the Ponseti method from the first cast to the foot-abduction brace, and the percutaneous Achilles tenotomy and its indications. [1]

A full-mark answer covers the CAVE mnemonic, the biomechanical sequence of the Ponseti method, the tenotomy at eight to ten weeks, and the foot-abduction brace to four to five years. [5]

The four classical deformities and the CAVE mnemonic (2 marks). The clubfoot, or the congenital talipes equinovarus, combines four deformities: the cavus (the high arch, the first ray plantarflexed), the adductus (the forefoot turned in, the medial displacement of the navicular and the cuboid), the varus (the heel turned in, the inversion of the calcaneus), and the equinus (the toes down, the plantarflexion contracture of the ankle). The mnemonic CAVE captures the deformities in the order the Ponseti method corrects them. The rigidity — the resistance to the passive correction — is the single feature that separates the structural clubfoot from the positional foot. [1][7]

The Ponseti method, casts one to five to seven (3 marks). The Ponseti method corrects the deformities in the cavus, adductus, varus, equinus sequence, using the viscoelastic creep of the immature ligament. The first cast corrects the cavus by elevating the first ray. The casts two to four or five correct the adductus and the varus together, by abducting the foot around the head of the talus — the fulcrum of the correction — with the counter-pressure on the lateral talar head. As the foot abducts, the navicular reduces onto the head of the talus, the calcaneus everts beneath the talus, and the cuboid aligns on the calcaneus. The casts are the long-leg above-knee casts, changed weekly, for a total of five to seven. The sequence is biomechanical: the talonavicular joint corrects before the ankle, because a premature dorsiflexion against a tight posterior capsule produces the rocker-bottom foot. [1][3]

The percutaneous Achilles tenotomy (2 marks). The percutaneous Achilles tenotomy is performed at eight to ten weeks, when the cavus, the adductus, and the varus are corrected but the equinus persists — typically when the Pirani hindfoot score is above one. The tenotomy is a minor procedure under the local anaesthetic or the sedation, with a small ophthalmic scalpel or a tenotomy needle, through a medial approach at the insertion or one centimetre above. It is performed in roughly eighty to ninety percent of the idiopathic clubfeet, and it releases the tight Achilles tendon that the casts cannot overcome. The post-tenotomy cast is worn for three weeks in the dorsiflexed position. [1][5]

The foot-abduction brace (2 marks). The foot-abduction brace is the shoes-and-bar device holding the affected foot at seventy degrees of external rotation (sixty to seventy for the affected, thirty to forty for the unaffected in the unilateral case) and fifteen degrees of dorsiflexion. It is worn full-time (twenty-three hours a day) for the first three months after the last cast, then nightly (twelve to fourteen hours, at the night and the nap) to the age of four to five years. The brace compliance, more than the casting or the tenotomy, is the single greatest determinant of the long-term success, and the family-centred counselling — the explanation of the rationale, the peer support, and the regular review — is the safeguard. [3]

The long-term outcome (1 mark). The Cooper and Dietz thirty-year follow-up showed the near-normal function, the painless feet, and only the minor strength deficits (about fifteen percent less calf strength) compared with the controls. The patient walks, runs, and plays sport without the limitation. [2]