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Vertical Talus (congenital convex pes valgus)

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Topic updated on 02/07/14 10:21pm
Introduction
  • A rare disorder consisting of an irreducible dorsal dislocation of the navicular on the talus producing a rigid flatfoot deformity
  • Pathoanatomy
    • rockerbottom (convex pes valgus) deformity consists of
      • fixed hindfoot equinovalgus
        • due to contracture of the Achilles and peroneal tendons
      • rigid midfoot dorsiflexion
        • secondary to the dislocated navicular
      • forefoot abducted and dorsiflexed
        • due to contractures of the EDL, EHL and tibialis anterior tendons
  • Genetics
    • a positive family history is present in up to 20% of patients
  • Associated conditions
    • approximately 50% associated with a neuromuscular or genetic disorder 
      • myelodysplasia (common)
      • arthrogryposis
      • diastematomyelia
      • chromosomal abnormalities
  • Prognosis 
    • poor in untreated cases and associated with significant disability
  • Oblique talus
    • talonavicular subluxation that reduces with forced plantarflexion of the foot
    • treatment typically consists of observations and shoe inserts
      • some require surgical pinning of the talonavicular joint and achilles lengthening for persistent subluxation
Presentation
  • Physical exam
    • rigid foot deformity (described above)
    • talar head is prominent in medial plantar arch on exam
      • produces a convex plantar surface
    • patient may demonstrate a "peg-leg" or a calcaneal gait due to decreased push-off 
    • a careful neurologic exam needs to be performed
      • due to frequent association with neuromuscular disorders
Imaging
  • Radiographs
    • lateral
      • vertically positioned talus & dorsal dislocation of navicular  q
      • line in long axis of talus passes below the first metatarsal-cuneiform axis
        • before ossification of navicular at age 3, the first metatarsal is used as a proxy for the navicular on radiographic evaluation
    • forced plantar flexion lateral 
      • shows persistent dorsal dislocation of the talonavicular joint 
        • oblique talus reduces on this view
      • Meary's angle > 20° (between line of longitudinal axis of talus and longitudinal axis of 1st metatarsal)  
    • forced dorsiflexion lateral
      • reveals fixed equinus
    • AP
      • valgus of the midfoot
      • talocalcaneal angle > 40° (20-40° is normal) 
  • MRI
    • considered for evaluation of the neural axis if an associated neuromuscular disorder is suspected
Differential Diagnosis
  • Oblique talus 
    • reduces with forced plantar flexion
  • Calcaneovalgus foot deformity
  • Tarsal coalition
  • Paralytic pes valgus
  • Pes planus valgus
Treatment
  • Nonoperative
    • preoperative serial manipulation and casting for three months
      • indications
        • indicated preoperatively to stretch the dorsal soft-tissue structures q
        • typically does not eliminate the need for surgery
      • technique
        • foot is held in plantarflexion and inversion 
  • Operative
    • surgical release and talonavicular reduction and pinning 
      • indications
        • indicated in most cases
        • performed at 6-12 months of age
      • technique
        • involves extensive release of talus with lengthening of contracted dorsolateral tendons (peroneals, Achilles, extensors) 
        • talonavicular joint is reduced and pinned while reconstruction of the plantar calcaneonavicular (spring) ligament is performed 
    • minimally invasive correction
      • indications
        • new technique performed in some centers to avoid complications associated with extensive surgical releases
      • technique
        • principles for casting are similar to the Ponseti technique used clubfoot
        • serial casting utilized to stretch contracted dorsal and lateral soft tissue structures and gradually reduced talonavicular joint
        • once reduction is achieved with cast, closed or open reduction is performed and secured with pin fixation 
        • percutaneous achilles tenotomy is required to correct the equinus deformity
    • talectomy
      • indicated in resistent case

 

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Qbank (5 Questions)

TAG
(OBQ09.29) What is the preferred treatment for newly diagnosed irreducible congenital vertical talus in a toddler? Topic Review Topic

1. Casting followed by open reduction and Achillies lengthening
2. Serial Ponseti method casting
3. Percutaneous achillies lengthening
4. Talectomy with tendon interposition
5. Subtalar fusion with soft tissue release

PREFERRED RESPONSE ▶
TAG
(OBQ07.154) Which of the following is not characteristic of the pathologic process displayed in Figure A. Topic Review Topic
FIGURES: A          

1. Dislocation of the talonavicular joint
2. Associated with posteromedial tibia bowing
3. Associated with neural tube defects
4. Associated with arthrogryposis
5. Rigid rocker bottom deformity

PREFERRED RESPONSE ▶
TAG
(OBQ06.127) An 13-month-old boy is evaluated for a foot deformity and asymmetric gait. A clinical photo is shown in Figure A. A plantarflexion lateral radiograph is shown in Figure B. What is the most likely diagnosis? Topic Review Topic
FIGURES: A   B        

1. Talipes equinovarus
2. Congenital vertical talus
3. Congenital oblique talus
4. Skewfoot
5. Normal radiographic findings

PREFERRED RESPONSE ▶
TAG
(OBQ04.115) A 2-month old infant is born with a rocker-bottom foot deformity. A radiograph is shown in figure A. Why is the initial treatment manipulation and casting? Topic Review Topic
FIGURES: A          

1. to help stretch the dorsolateral soft-tissue before surgery
2. the deformity usually corrects with non-operative treatment
3. surgery is usually deferred until 5 years of age
4. surgery is usually deferred until 10 years of age
5. surgery does not help this condition

PREFERRED RESPONSE ▶



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Gait evaluation of a patient with bilateral neglected vertical tali deformities
3/15/2012
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