Dr. Kevin Yip

Dr Kevin Yip
Orthopaedic Surgeon
MBBS(UK), FRCS(EDIN), FAM(SING), FHKCOS(ORTHO)

Featured on Channel NewsAsia

Vertical Talus

Basics

Description
  • Congenital vertical talus is an uncommon disorder, a rigid flatfoot that requires early identification and treatment.
  • Its essence is a dislocation of the talonavicular joint with associated adaptive changes.
  • It may be unilateral or bilateral.
  • >1/2 of affected patients have other neurologic, genetic, or connective tissue disorders.
  • The deformity occurs in utero, but it may be 1st identified any time from infancy to adulthood.
  • Classification:
    • Isolated
    • Syndrome-related
  • Synonyms: Congenital convex pes planus; Congenital rigid rocker-bottom foot
Epidemiology
Incidence
  • Rare, but a high association with other disorders and anomalies:
    • 10% of children with myelodysplasia have congenital vertical talus.
    • It also can be associated with trisomy 13, 15, and 18 and with arthrogryposis or Larsen syndrome.
  • In 20-40% of cases, congenital vertical talus occurs as an isolated anomaly.
  • It affects males and females equally.
Risk Factors
  • Myelodysplasia
  • Ligamentous laxity
  • Arthrogryposis multiplex
Genetics
  • Unknown, but probably variable
  • In some cases, vertical transmission as an autosomal dominant trait with incomplete penetrance has been described.
Etiology
  • Muscle imbalance between the dorsiflexor muscles of the forefoot and plantarflexor muscles of the hindfoot cause disruption in the middle of the foot (talonavicular joint).
  • Ligamentous laxity and in utero malposition may be causative factors in some cases.
Associated Conditions
  • Arthrogryposis
  • Larsen syndrome
  • Myelomeningocele
  • Trisomy 13, 15, 18
Diagnosis
Signs and Symptoms
  • Signs: Moderate reversal of the arch and a crease on the dorsum of the foot near the sinus torsi
  • Symptoms: Lack of push-off strength, painful callus under the head of the talus possible if untreated by walking age
Physical Exam
  • Check the other extremities, as well as the spine, for anomalies.
  • Measure strength in both lower extremities.
  • Observe the foot in stance and gait if the child is walking.
  • It is easily distinguishable from the more common calcaneovalgus and flexible flatfoot.
  • The sole of the foot is convex, has a rocker bottom, and is rigid.
  • The heel is in a fixed equinus with a tight Achilles tendon.
  • The head of the talus is prominent and palpable medially in the sole of the foot.
  • The hindfoot is in valgus.
  • The forefoot is abducted and in dorsiflexion at the midtarsal joint (Fig. 1).
  • As the patient becomes older, the appearance of the foot becomes more distinctive.
    Fig. 1. Vertical talus produces a dorsal crease and a plantar prominence.
Tests
Imaging
  • Obtain radiographs.
  • The talus is plantarflexed (on lateral films) and angled medially (on AP films).
  • The navicular is dislocated dorsally and is perched on the neck of the talus.
  • The forefoot is displaced dorsally and abducted.
  • The calcaneus is in a fixed equinus.
  • Only the most posterior aspect of the talus articulates with the tibia and, in extreme cases, the talus is parallel to the tibia.
  • The diagnosis is confirmed in extreme plantarflexed views, when the navicular will not reduce, and the line through the talar axis passes plantar to the metatarsal axis.
    • Normal is dorsal to the cuboid and in line with the metatarsal axis.
    • However, the navicular does not ossify until ~3 years of age, in the normal foot or the foot with congenital vertical talus.
    • The position of the navicular may be inferred from the orientation of the first metatarsal.
Pathological Findings
  • The calcaneus is in equinus and laterally displaced.
  • The talus is hypoplastic, angled medially, and plantarflexed.
  • Fixed dorsal dislocation of the navicular is noted.
  • Contracture of the Achilles tendon (posteriorly) is evident.
  • Contracture of the toe extensor and the tibialis anterior (anteriorly) is seen.
  • Specially positioned plantar flexion lateral radiograph is helpful (see later).
Differential Diagnosis
  • Calcaneovalgus foot
  • Flexible flatfoot

P.481
Treatment
General Measures
  • Stretching
  • Surgery
  • If the condition is recognized, surgical intervention is preferred before the patient is 2 years old.
  • Casting and manipulation alone usually are not effective, although they should be used preoperatively to stretch soft tissue.
Activity
Unrestricted
Surgery
  • The essential features are reduction (open or closed) and pinning of the talonavicular joint.
    • Although open surgery previously was the norm, reduction and percutaneous pin fixation with an Achilles tenotomy recently has become an accepted technique.
    • The associated contracted tendons (Achilles and, if needed, anterior tibialis) also should be lengthened.
    • The medial joint capsules may be stabilized, or, in children 3 years old, the talonavicular joint may be fused.
    • Children >5 years old may require triple arthrodesis.
  • Postoperative percutaneous PINS of the talonavicular joint usually are removed at 6 weeks.
  • Postoperative bracing often is used for a number of months.
    • Late treatment requires subtalar fusion.
    • Recurrent deformity is treated with soft-tissue reconstruction and subtalar fusion.
  • In adolescents and adults, salvage is performed by triple arthrodesis and often requires removal of a large portion of the talus.
Follow-up
Patients should be followed throughout childhood to monitor the growth of the foot.
Prognosis
If untreated, the condition produces progressive disability.
Complications
  • Complications of nontreatment: Callus, skin breakdown, poor push-off
  • Complications of treatment: Stiffness, residual varus or valgus, need for additional surgery
Patient Monitoring
Even after surgery, the patient should be followed periodically to verify normal growth.
Miscellaneous
Codes
ICD9-CM
754.69 Congenital vertical talus
Patient Teaching
  • Patients should be informed of the chances of inheritance in future children.
  • The natural history of this condition, if left untreated, which is severe callus formation, skin breakdown, and poor push-off, also should be discussed.
  • The risk of hip dysplasia should be mentioned and excluded.
  • The possible need for additional surgery should be mentioned.
FAQ
Q: How is vertical talus commonly recognized?
A: By the deep crease in the sinus tarsi and the plantar convexity.
Q: Does it resolve spontaneously?
A: No, it does not.

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