congenital vertical talus

Question 1

Epidemiology

Answer 1

• Rare, 1:150,000 births
• 50% associated with neuromuscular disease or chromosomal aberrations
  
  • Myelomeningocele
  • Arthrogryposis
  • Diastematomyelia
  • congenital dislocation of the hip
  • cerebral palsy
  • spinal muscular atrophy
• 50% bilateral
• M:F ratio of 2:1

Question 2

Pathoanatomy

Answer 2

Pathoanatomy

• rigid foot deformity
  
  • irreducible dorsolateral navicular dislocation
  • vertically oriented talus
  • calcaneal eversion with attenuated spring ligament
• soft tissue contractures
  
  • displacement of peroneal longus and posterior tibilais tendon so they function as dorsiflexors rather than plantar flexors
  • contracture of the Achilles tendon

Question 3

whats oblique vertical talus?

Answer 3

oblique talus

• anatomic variant
  
  • talonavicular subluxation that reduces with forced plantarflexion of the foot
• treatment
  
  • typically consists of observation and shoe inserts
  • some require surgical pinning of the talonavicular joint and achilles lengthening for persistent subluxation

Question 4

Physical exam

Answer 4

• rigid rockerbottom deformity
  
  • 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
• prominent talar head
  
  • can be palpated in medial plantar arch on exam
    
    • produces a convex plantar surface
• gait abnormality
  
  • patient may demonstrate a “peg-leg” or a calcaneal gait due to poor push-off power
  • limited forefoot contact, excessive heel contact
• neurologic deficits
  
  • a careful neurologic exam needs to be performed due to frequent association with neuromuscular disorders

Question 5

Radiographic Findings

Answer 5

• recommended views
  
  • AP, oblique and lateral foot
• findings
  
  • lateral
    
    • vertically positioned talus & dorsal dislocation of navicular
      
      • line along 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
  • AP
    
    • talocalcaneal angle > 40° (20-40° is normal)
• alternative views
  
  • forced plantar flexion lateral radiograph is diagnostic
    
    • 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

Question 6

Nonoperative Rx

Answer 6

serial manipulation and casting

• indications
  
  • indicated preoperatively to stretch the dorsolateral soft-tissue structures
  • foot is manipulated into inversion and plantarflexion
• typically still requires closed vs open pinning of the talonavicular joint with percutaneous achilles tenotomy

Question 7

list the Operative options

Answer 7

1. surgical release and talonavicular reduction and pinning
2. minimally invasive correction
3. talectomy
4. triple arthrodesis

Question 8

Discuss the operative management

Answer 8

• surgical release and talonavicular reduction and pinning
  
  • indications
    
    • indicated in most cases
    • performed at 6-12 months of age
  • technique
    
    • involves pantalar release with concomitant lengthening of peroneals, Achilles, and toe extensors
    • talonavicular joint is reduced and pinned while reconstruction of the plantar calcaneonavicular (spring) ligament is performed
    • concomitant tibialis anterior transfer to talar neck
• 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 resistant case
• triple arthrodesis
  
  • as salvage procedure