Congenital Vertical Talus
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Direct answer
Congenital vertical talus is a rare, rigid deformity of the foot in which the talus lies vertically, producing a convex rocker-bottom sole with the navicular displaced dorsally on the talar head. The diagnosis is confirmed on a plantar-flexion lateral radiograph, which shows the talus staying vertical and the forefoot failing to reduce onto it. Treatment starts with reverse Ponseti casting, with surgery for deformities that do not respond.
What you must remember
- Rocker-bottom foot: a rigid, convex sole with the hindfoot in equinus and the forefoot dorsiflexed and abducted.
- Vertical talus: the long axis of the talus points vertically, with the navicular sitting dorsally on the talar head and neck.
- Plantar-flexion lateral view: the key test, showing that the talus does not plantar flex and the navicular does not reduce.
- Associations: neuromuscular conditions such as myelomeningocele and arthrogryposis, and chromosomal syndromes such as trisomy 18.
- Contrast with clubfoot: clubfoot is a concave equinovarus deformity, and it is usually corrected by the Ponseti method.
- Reverse Ponseti: serial casting that brings the forefoot into plantar flexion and inversion (adduction), the opposite of the deformity, to reduce the navicular onto the talar head; a percutaneous tendo-Achilles tenotomy and talonavicular pinning usually follow.
- Surgery: reserved for deformities that fail casting, typically with release of the talonavicular joint and tendo-Achilles lengthening.
Where the exam tries to catch you
Examiners test the lateral view, the contrast with clubfoot and the associated conditions.
- Trap: treating a rigid rocker-bottom foot with the standard Ponseti method. Correct: a vertical talus needs a reverse Ponseti approach or surgery, because the forefoot is dorsiflexed and abducted rather than adducted.
- Trap: relying on the anteroposterior view to diagnose it. Correct: the plantar-flexion lateral radiograph is the key view, showing that the talus remains vertical while the forefoot cannot be reduced.
- Trap: missing neuromuscular or chromosomal causes. Correct: myelomeningocele, arthrogryposis and trisomy 18 are classic associations that need evaluation.
Frequently asked questions
What is the key radiograph for diagnosing congenital vertical talus?
The plantar-flexion lateral radiograph is the key view for congenital vertical talus. It shows that the talus stays vertically aligned and that the navicular does not reduce onto it, confirming an irreducible deformity.
How does congenital vertical talus differ from clubfoot?
Congenital vertical talus produces a rigid, convex rocker-bottom foot with the forefoot dorsiflexed and abducted, whereas clubfoot produces a concave equinovarus foot with the forefoot adducted. The two are distinguished clinically and radiologically, and their treatment differs.
What is the reverse Ponseti approach in congenital vertical talus?
The reverse Ponseti approach applies serial casts that move the forefoot into plantar flexion and inversion, progressively bringing the navicular back onto the talus, usually finished with a tendo-Achilles tenotomy and pinning. It is used as the initial treatment, with surgery reserved for deformities that fail to correct with casting.
Which conditions are associated with congenital vertical talus?
Congenital vertical talus is associated with neuromuscular conditions such as myelomeningocele and arthrogryposis, and with chromosomal syndromes such as trisomy 18. Children with the deformity therefore need a search for these associations alongside the foot treatment.