http://upload.orthobullets.com/topic/4066/images/clinical photo - courtesy Miller_moved.png
http://upload.orthobullets.com/topic/4066/images/Neutral lateral xray - courtesy Miller_moved.png
http://upload.orthobullets.com/topic/4066/images/plantar flexion lateral xray - courtesy Miller_moved.png
http://upload.orthobullets.com/topic/4066/images/Meary's angle_moved.png
Introduction
  • Irreducible dorsal dislocation of the navicular on the talus producing a rigid flatfoot deformity
  • Epidemiology:
    • Rare, 1:150,000 births
    • 50% associated with neuromuscular disease or chromosomal aberrations  
      • Myelomeningocele
      • Arthrogryposis
      • Diastematomyelia
  • 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
  • Genetics
    • a positive family history is present in up to 20% of patients
  • Prognosis 
    • poor in untreated cases and associated with significant disability
  • Differential diagnosis
    • 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
Presentation
  • Physical exam
    • 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
Imaging
  • Radiographs
    • recommended views
      • AP, oblique and lateral foot 
    • findings
      • 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
      • 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
  • MRI 
    • neuraxial imaging should be performed to rule out neurologic disorder
Differential Diagnosis
  • Oblique talus 
    • reduces with forced plantar flexion
    • treatment is observation vs casting
  • Calcaneovalgus foot deformity
  • Tarsal coalition
  • Paralytic pes valgus
  • Pes planovalgus
Treatment
  • Nonoperative
    • serial manipulation and casting for three months
      • indications
        • indicated preoperatively to stretch the dorsolateral soft-tissue structures q
      • typically followed by surgical release and pinning of the talonavicular joint with percutaneous achilles tenotomy
  • Operative
    • surgical release and talonavicular reduction and pinning 
      • indications
        • indicated in most cases
        • performed at 12-18 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
Complications
  • Missed vertical talus
    • reconstructive options are less predictable after age 3, and patients may require triple arthrodesis as salvage procedure
 

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Questions (4)

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

QID:2842
1

Casting followed by open reduction and Achillies lengthening

84%

(1254/1485)

2

Serial Ponseti method casting

7%

(98/1485)

3

Percutaneous achillies lengthening

2%

(25/1485)

4

Talectomy with tendon interposition

4%

(63/1485)

5

Subtalar fusion with soft tissue release

3%

(43/1485)

Select Answer to see Preferred Response

PREFERRED RESPONSE 1

The preferred treatment of congenital vertical talus (CVT) is surgical reduction of the navicular onto the reduced talus with soft-tissue releases in either a staged or one-step procedure. Casting prior to surgery is helpful in stretching the contracted dorsal soft-tissues but does not typically reduce the talonavicular joint. Manipulation and casting have been tried as definitive treatment, but most authors now agree that surgical treatment is required.

Surgical treatment requires lengthening of the Achilles tendon and sometimes the dorsiflexors, as well as sectioning of the midfoot capsules. A subtalar fusion is not performed initially, although it may be required if there is recurrence. Untreated, patients develop an awkward gait due to a rocker bottom type foot, a painful rigid foot as well as calluses under the midfoot.

The Sullivan article reviews causes of pediatric flat foot and cautions the need to rule out CVT.

The Drennan instructional course lecture reviews CVT etiology, diagnosis, and treatment.


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(OBQ07.154) Which of the following is not characteristic of the pathologic process displayed in Figure A. Review Topic

QID:815
FIGURES:
1

Dislocation of the talonavicular joint

5%

(84/1609)

2

Associated with posteromedial tibia bowing

57%

(923/1609)

3

Associated with neural tube defects

15%

(243/1609)

4

Associated with arthrogryposis

9%

(141/1609)

5

Rigid rocker bottom deformity

13%

(210/1609)

Select Answer to see Preferred Response

PREFERRED RESPONSE 2

Congenital vertical talus (CVT) is not associated with posteromedial bowing.

Congenital vertical talus (CVT) presents as a fixed rocker bottom foot. The hindfoot is in equinus and the forefoot is in dorsiflexion, producing a fixed midfoot dislocation through the talonavicular joint that does not correct with plantar flexion. CVT is a surgical problem that requires peritalar release to reduce the talonavicular and talocalcaneal articulations. Surgical treatment is required but preoperative casting can stretch the contracted tissues to facilitate surgery. Arthrodesis is not needed to correct deformity as soft tissue release and reduction have been shown to have acceptable results.

Drennan presents a Level 5 review article. In CVT, the talonavicular joint is irreducibly dislocated dorsally. CVT is usually associated with other congenital or neuromuscular abnormalities such as neural tube defects (myelomeningocele), neuromuscular disorders (arthrogryposis), malformation syndromes, and chromosomal aberrations.

Illustration A depicts the lateral radiograph demonstrating plantar flexion of an oblique (A) and vertical (B) talus. In the oblique talus, the navicular (unossified) and first metatarsus (and thus the talonavicular joint) line up in plantar flexion. In a true congenital vertical talus, the the navicular (unossified) and first MT remain dorsal to the talus in plantar flexion.

Incorrect Answer:
Calcaneovalgus foot is associated with posteromedial bowing of the tibia.

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(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? Review Topic

QID:313
FIGURES:
1

Talipes equinovarus

4%

(49/1170)

2

Congenital vertical talus

62%

(722/1170)

3

Congenital oblique talus

29%

(339/1170)

4

Skewfoot

1%

(14/1170)

5

Normal radiographic findings

3%

(38/1170)

Select Answer to see Preferred Response

PREFERRED RESPONSE 3

The clinical presentation and radiographic findings are consistent with congenital oblique talus (COT), not congenital vertical talus (CVT). The plantarflexion lateral radiograph is key to differentiating between these two conditions. In congenital oblique talus, the talonavicular joint will reduce and the talus will parallel the first metatarsal on plantarflexion radiographs. However, the talus will not reduce in CVT, and with plantar flexion the long axis of the first metatarsal remains dorsal to the long axis of the talus. This is shown in Illustration A, which demonstrates plantarflexion radiographs of a congenital oblique talus (A) and congenital vertical talus (B). The distinction is important as congenital vertical talus is a true dislocation of the talonavicular joint which requires casting followed by surgery.

Mazzaocca et al retrospectively evaluated 33 feet with congenital vertical talus who were treated surgical release through either a traditional posterior approach or a single stage dorsal approach. The feet treated with the dorsal approach had shorter surgical times, better clinical outcomes, fewer complications (AVN was significant in posterior approach), and fewer revisions.

Kodros et al reviewed 55 patients treated with a single stage Cincinnati incision (a transverse posterior approach at the level of the tibiotalar joint). There were no cases of AVN. Ten feet required a secondary surgery. At final clinical and radiographic follow-up 75% were stratified as good results and 25% were fair.

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(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? Review Topic

QID:1220
FIGURES:
1

to help stretch the dorsolateral soft-tissue before surgery

73%

(522/717)

2

the deformity usually corrects with non-operative treatment

21%

(154/717)

3

surgery is usually deferred until 5 years of age

4%

(28/717)

4

surgery is usually deferred until 10 years of age

0%

(2/717)

5

surgery does not help this condition

1%

(7/717)

Select Answer to see Preferred Response

PREFERRED RESPONSE 1

The X-ray shows a plantar flexion lateral foot X-ray denoted by the plantar flexed position of the toes. This X-ray denotes a dorsally dislocated talonavicular joint consistent with congenital vertical talus resulting in a rocker bottom foot.

The etiology, inheritance, and incidence of this entity are unknown, though a family tendency has been reported. In congenital vertical talus, the hindfoot is fixed in an equinovalgus position and the forefoot is abducted and dorsiflexed in the midtarsal region. It is rigid and uncorrectable. The plantar surface of the foot has a rounded or convex appearance (“rocker-bottom feet”) and children can develop an awkward gait due to a painful rigid foot and calluses under the midfoot.

Lateral radiographs in a neutral and maximally plantarflexed position will confirm the diagnosis, showing that in the neutral position the calcaneus is in equinus, the forefoot is fixed in dorsiflexion, and there is a dorsal talonavicular dislocation. These findings do not correct in the maximally plantar flexed position. In the similar oblique talus, the dorsally positioned navicular will reduce in line with the talus.

Treatment for the condition should begin as early as possible. Most authors agree that surgical treatment is required for correction of the deformity. Casting before surgery is performed to stretch the soft tissues, improve final surgical correction and minimize surgical intervention. Historically, a single-stage procedure through an extensile incision was most commonly used. Dobbs et al describe the success with serial manipulation and cast immobilization followed by talonavicular pin fixation and percutaneous tenotomy of the Achilles tendon providing excellent results.

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