Congenital Vertical Talus

The four key deformities:

• Hindfoot equinus: The calcaneus is fixed in plantarflexion, tethered by a contracted tendo-Achilles and posterior capsule.
• Hindfoot valgus: Increased talocalcaneal divergence.
• Midfoot dorsiflexion / dorsal dislocation: The navicular sits dorsal to the talar neck, held by contracted dorsal structures (tibialis anterior, extensor digitorum longus, extensor hallucis longus, peroneus tertius, and the dorsal talonavicular capsule). The peroneals and tibialis anterior become displaced and act as deforming dorsiflexors.
• Forefoot abduction and dorsiflexion.

The hindfoot equinus is masked by the dorsiflexed midfoot — the sole becomes convex (rocker-bottom), with the prominent talar head palpable medially in the sole. The deformity is rigid and irreducible, which is the cardinal feature separating CVT from its flexible mimics.

X-rays (Simulated Weight Bearing / Forced Views):

1. Lateral Forced Plantarflexion (KEY VIEW):
   • Normal: Axis of talus lines up with 1st metatarsal.
   • CVT: Axis of talus passes BELOW the 1st metatarsal. The navicular (and forefoot) remains dorsally dislocated and cannot be reduced onto the talar head.
2. Lateral Forced Dorsiflexion:
   • Shows fixed equinus of the calcaneus (calcaneus does not dorsiflex).
3. AP View:
   • Increased Talo-Calcaneal angle (Kite's angle) - indicating valgus.

Note: The navicular is not ossified until age 3, so you infer its position by the 1st metatarsal.

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The diagnosis rests on specific angles and, critically, on forced (stress) views — the topic above names the talar-axis–first-metatarsal relationship, "TAMBA", Kite's angle and Meary's, but the actual measurement protocol is worth setting out because it is the examinable crux and the way CVT is separated from its reducible mimic.

The angles (because the navicular is unossified, the first metatarsal is the surrogate)

• Talar axis–first metatarsal base angle (TAMBA): the lateral angle between the long axis of the talus and the first metatarsal. It is normally close to zero (the axes are roughly colinear — the lateral talo–first-metatarsal / Meary relationship); in CVT the talus is plantarflexed so this angle is grossly positive (plantar-apex) — treatment series report it improving from about 60 degrees toward 15 degrees with correction.
• Calcaneal axis–first metatarsal base angle (CAMBA): assesses the calcaneus-to-forefoot relationship and complements TAMBA.
• Talocalcaneal (Kite) angle: increased on both AP and lateral, reflecting the hindfoot valgus/divergence (series quote roughly 70 degrees correcting to about 31 degrees). General definition of Meary's angle is covered in the dedicated Meary angle topic.

The forced views make the diagnosis (a static film does not)

• Forced maximal PLANTARFLEXION lateral — the key view: this tests whether the talonavicular joint reduces. In a normal foot or an oblique talus the forefoot/first-metatarsal axis swings back into line with the talar axis (the navicular reduces). In CVT the talus stays vertical and the first-metatarsal axis remains dorsal — it does not align (irreducible). This single view is what separates CVT from the reducible oblique talus.
• Forced maximal DORSIFLEXION lateral: demonstrates the fixed hindfoot equinus — the calcaneus fails to dorsiflex and stays plantarflexed, confirming the rigid equinus that is clinically masked by the rocker-bottom midfoot.

Protocol (Dobbs method):

• Immobilization: Long-leg cast in the corrected position for ~6-8 weeks. The talonavicular K-wire is typically removed at ~5-6 weeks.
• Bracing: After cast removal, an ankle-foot orthosis (AFO) or solid-ankle shoe is used to maintain correction. Many surgeons use a foot-abduction-style brace/AFO part-time for 1-2 years, mirroring the maintenance phase of Ponseti clubfoot care.
• Weight bearing: Permitted once the cast is removed and the foot is plantigrade; mobilisation is encouraged.
• Surveillance: Recurrence (especially in teratologic feet) is the dominant late problem, so children are followed until skeletal maturity. Early recurrence is managed with repeat casting; established relapse may need revision surgery.

• Dobbs Method: High success rate (greater than 90% initial correction). Reduced stiffness compared to open surgery.
• Untreated: Severe disability, painful calluses on sole (talar head), difficulty wearing shoes.

About half of CVT is teratologic, and the topic repeatedly flags these feet as "more resistant" with "higher recurrence" — but what actually changes in management deserves to be explicit, because the teratologic foot is the one that relapses.

Why it behaves worse

• Teratologic CVT accompanies a persisting driver — the fixed contractures of arthrogryposis, the ongoing muscle imbalance and sensory loss of myelomeningocele/spina bifida, or a chromosomal syndrome (trisomy 13/18). Because the underlying neuromuscular cause keeps acting, these feet are more rigid at presentation and recur far more often than idiopathic feet (independent cohorts report recurrence well above the original idiopathic series).

How management adapts (the principle is the same; the threshold differs)

• Still start with reverse-Ponseti casting — it achieves initial correction even in syndromic and older feet — but expect more casts and a lower threshold to add a limited dorsal/talonavicular capsulotomy at the index operation (rather than tenotomy and pinning alone) to reduce relapse.
• Brace diligently and follow to skeletal maturity: maintenance bracing is not optional here, and surveillance must continue because relapse is the rule, not the exception.
• In the insensate (myelomeningocele) foot, watch the skin: cast pressure sores and plantar ulceration over the prominent talar head are real hazards.
• Salvage is needed more often: for repeated failures or neglected syndromic feet, tailored limited release or naviculectomy (and, at maturity, triple arthrodesis) is reached for sooner than in idiopathic disease.
• Treat the child, not just the foot: screen for and co-manage the spine, hips and the underlying condition (the syndrome itself is covered in the arthrogryposis and related topics).

Global epidemiology:

• Rare congenital deformity, ~1 in 10,000 live births; bilateral in roughly half.
• Around 50% are teratologic, associated with arthrogryposis, myelomeningocele, trisomies (13/18) and other syndromes — proportions vary with referral pattern and access to prenatal screening.

Practice consensus (no single national guideline governs CVT):

High- vs limited-resource variation:

• Where neonatal screening and paediatric orthopaedic services exist, most feet present and are cast in infancy with minimally invasive surgery.
• In limited-resource or remote settings, late/neglected presentation is more common, shifting the balance toward salvage procedures (naviculectomy, talectomy, later triple arthrodesis). Reverse-Ponseti casting is attractive globally because it is low-cost and avoids major open surgery.
• No dedicated implant registry exists for CVT (unlike arthroplasty); evidence rests on single-centre series, so practice is guided by consensus rather than registry data.