Treatment of Vertical Talus

 

 

 

 

DEFINITION

Congenital vertical talus is a rare foot deformity that presents at birth as a rigid flatfoot deformity.

Although the exact incidence of vertical talus is unknown, it has an estimated prevalence of 1 in 10,000 live births.

It is associated with neuromuscular disorders or genetic syndromes in half of all cases, whereas the remainder occurs as isolated deformities.

Of the 50% of cases of vertical talus that are isolated, almost 20% of these have a positive family history of other members affected with vertical talus.

 

 

ANATOMY

 

The hindfoot is in marked equinus and valgus caused by contracture of the tendo Achilles and the posterolateral ankle and subtalar joint capsules.6, 12

 

The midfoot and forefoot are dorsiflexed and abducted relative to the hindfoot due to contractures of the tibialis anterior tendon, extensor digitorum longus, extensor hallucis brevis, peroneus tertius, extensor hallucis longus tendons, and the dorsal aspect of the talonavicular capsule.

 

The navicular is dorsally and laterally dislocated on the head of the talus resulting in the development of a hypoplastic and wedge-shaped navicular.

 

The talar head and neck are flattened and medially deviated.

 

The extreme plantarflexion of the talus results in attenuation of the calcaneonavicular or spring ligament and a rocker bottom appearance of the foot where the sole is convex and deep creases are seen in the dorsolateral aspect of the foot.

 

The calcaneus is plantarflexed, leading often to dorsolateral subluxation or frank dorsal dislocation of the cuboid on the calcaneus.

 

The posterior tibial tendon is usually subluxed anteriorly over the medial malleolus, whereas the peroneus longus and brevis may be subluxed over the lateral malleolus; the subluxed tendons may then function as ankle dorsiflexors rather than plantarflexors.

 

PATHOGENESIS

 

With a host of different genetic and neuromuscular etiologies for vertical talus, it is likely that the pathophysiologic basis for its development is heterogeneous in nature.

 

Genetic factors play a significant role not only in syndromic cases but in many isolated cases as well.17, 19

 

The most common gene mutations identified to date for isolated vertical talus are in the HOXD10 gene, encoding a homeobox transcription factor gene expressed in early limb development and the GDF5 (cartilage-derived morphogenetic protein-1) gene.8, 9

 

Some neurologic cases present with significant muscle imbalances that can explain the resulting clinical deformity.

 

Congenital muscle abnormalities are responsible in other patients as supported by abnormal skeletal muscle biopsies.

 

Magnetic resonance angiography in this patient population demonstrates vascular insufficiencies in the lower limb that may be an etiologic factor.

 

NATURAL HISTORY

 

Left untreated, the deformities present in vertical talus worsen with weight bearing as secondary adaptive changes occur in the tarsal bones.

 

Painful callosities develop along the plantar medial border of the foot around the prominent and unreduced talar head.

 

Heel strike does not occur, shoe wear becomes difficult, and pain develops.

 

PATIENT HISTORY AND PHYSICAL FINDINGS

 

Hindfoot equinus, hindfoot valgus, forefoot abduction, and forefoot dorsiflexion are present in all patients with vertical talus in the newborn period, but the deformities vary in severity resulting in many patients not being diagnosed correctly at birth (FIG 1).

 

 

In congenital vertical talus, the plantar surface of the foot is convex, creating a rocker bottom appearance. There are deep creases on the dorsolateral aspect of the foot.

 

The forefoot dorsiflexion results in a palpable gap dorsally where the navicular and talar head would normally be articulating.

 

The presence of active dorsiflexion and plantarflexion of the toes is recorded as absent, slight, or definitive. This should be recorded for the great toe alone as well as the lesser toes as a separate group.

 

 

 

 

FIG 1 • A. Convex plantar surface of the feet associated with bilateral congenital vertical talus. B. View from behind illustrating the deep creases on the dorsolateral aspect of the feet.

 

 

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Slight or absent ability to move the toes with stimulation correlates, in our experience, with vertical talus deformities that are more rigid and less responsive to treatment.

 

In addition to examining the feet, the physician should look for the presence of a sacral dimple which may signify a central nervous system anomaly.

 

IMAGING AND OTHER DIAGNOSTIC STUDIES

 

Standard radiographs in evaluation of vertical talus include an anteroposterior radiograph of the foot and three laterals of the foot: maximal dorsiflexion, maximal plantarflexion, and neutral (standing for older children).

 

The maximal plantarflexion lateral radiograph is the most critical film because a lateral talar axis-first metatarsal base angle (TAMBA) of greater than 35 degrees is pathognomonic for the disorder (FIG 2).

 

 

Values below 35 degrees do not rule out a vertical talus, however. In such cases, to differentiate a more flexible vertical talus from an oblique talus, the presence or absence of hindfoot equinus must be documented. If equinus is present, then the deformity is rigid and warrants treatment in the same manner as those vertical tali with a TAMBA angle of more than 35 degrees.

 

The forced dorsiflexion lateral demonstrates persistent rigid hindfoot equinus.

 

The anteroposterior radiograph demonstrates an increased talocalcaneal angle indicative of hindfoot valgus.

DIFFERENTIAL DIAGNOSIS

Oblique talus Calcaneovalgus foot

Posteromedial bow of the tibia

 

FIG 2 • Plantarflexion lateral radiograph of the left foot of the patient in FIG 1, demonstrating the lack of reduction of the talonavicular joint.

 

 

 

NONOPERATIVE MANAGEMENT

 

Older casting techniques were not successful in correcting vertical talus deformities.

 

 

With the advent of new casting technique,1, 10, 11 focused on the functional anatomy of the subtalar joint, excellent correction can be achieved leaving the need for only a minimally invasive surgery to stabilize the reduction.

SURGICAL MANAGEMENT

 

Correction of all rigid vertical tali should be considered due to the unfavorable natural history.

 

The use of the Dobbs method of serial manipulation and casting followed by temporary Kirschner wire stabilization of the talonavicular joint and a tendo Achilles tenotomy has provided a new treatment strategy that

avoids more extensive soft tissue release surgery while providing excellent correction and preserving ankle and subtalar mobility.1, 2, 3, 4, 5, 7, 10, 13, 14, 15, 20

 

Treatment should be initiated in the first 2 months of life if possible.

 

The goals are to provide flexible feet that are plantigrade and functional.

 

For syndromic and/or severely involved neuromuscular patients, careful consideration should be given to child's overall health and ambulatory potential before proceeding with treatment.

 

Preoperative Planning

 

The treatment process starting with serial casting should not be initiated with premature infants still in hospital and of low birth weight. These very small patients are difficult to fit into braces which are required to prevent relapse after correction is achieved.

 

The age of the patient is important in preoperative planning as a tibialis anterior tendon transfer to neck of talus should be considered for those patients older than 2 years at time of treatment.

 

Neural axis imaging should be performed for those patients in which abnormalities are present, suggestive of spinal pathology.

 

Positioning

 

 

Patient is positioned supine on radiolucent table. Nonsterile tourniquet is placed on proximal thigh.

 

 

TECHNIQUES

• Dobbs Method Part 1: Serial Manipulation

  The method of correction is based on a thorough understanding of the subtalar joint and the ability of the treating physician to accurately localize the head of the talus on the plantar medial aspect of the midfoot.

  The head of the talus is the fulcrum and the point around which the rest of the foot will be manipulated.

  All components of the deformity are corrected simultaneously with the exception of the hindfoot equinus, which is corrected last.

  The manipulations are gentle in nature and consist of stretching the foot into plantarflexion and adduction with one hand while counterpressure is applied with the thumb of the opposite hand gently pushing the talus dorsally and laterally (TECH FIG 1).

  It is essential not to touch the calcaneus during manipulations, as this can prevent the calcaneus from correcting from a valgus to a varus position.

  Manipulations are done weekly in the clinic and are gentle in nature. The head of the talus is palpated with the thumb of the examiner, and once identified, direct pressure is placed with the thumb on the head of the talus in a plantar and lateral direction while the examiner using the other hand brings the foot into plantarflexion and adduction.

   

  Ideally, an assistant is present during the manipulations as well to provide a counterfulcrum by applying gentle traction underneath the knee in the direction of the head of the patient. This allows

   

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  the physician to effectively plantarflex the foot without pulling the patient down the examination table.

   

   

   

  TECH FIG 1 • A,B. Direction of the manipulative forces applied to reduce a vertical talus deformity. The foot is stretched into plantarflexion and inversion while counterpressure is applied with the thumb to the medial aspect of the head of the talus. C. Position of the foot with maximum hindfoot varus and forefoot adduction before pinning of the talonavicular joint and lengthening of the Achilles tendon. The foot is also placed in maximum plantarflexion to ensure adequate stretching of the contracted dorsolateral tendons, joint capsules, and skin (not shown).

   

   

  After a minute or two of manipulations, a long-leg plaster cast is applied to hold the foot in the position achieved with stretching.

   

  The cast is applied in two sections with the short-leg portion applied first to allow the treating physician to make the appropriate molds.

   

  Once the plaster has been applied, the treating physician then molds carefully around the talar head, the malleoli, and above the calcaneus posteriorly.

   

  Once the plaster has set, the dorsum of the toes are exposed just enough to be able to assess circulation while leaving enough plaster dorsally to stretch the toes into plantarflexion.

   

  The cast is then extended above the knee, with the knee in 90 degrees of flexion.

   

  Casting and manipulations are repeated weekly in the clinic for an average of 5 to 6 weeks using the same manipulative technique but gaining more correction each time.

   

  The skilled physician can palpate when the talonavicular joint is reduced and visualize when the heel has corrected into varus.

   

  The position of the foot when the talonavicular joint is fully reduced is an extreme clubfoot position. This position is critical to achieve to adequately stretch the contracture dorsolateral soft tissues.

• Dobbs Method Part 2: Limited Surgery and Percutaneous Stabilization

   

  When reduction is achieved, the patient is scheduled for the operating room for stabilization of the talonavicular joint with a Kirschner wire followed by a percutaneous tendo Achilles tenotomy.

   

  In the operating room under tourniquet control and in the supine position, a small 1-cm incision is made dorsomedially over the talonavicular joint. This allows the surgeon, without opening the joint capsule in most cases, to ensure the talonavicular joint is reduced and aids in Kirschner wire placement.

   

  If the joint is not completely reduced, a small capsulotomy is made in the anterior subtalar joint which allows the placement of an elevator to gently complete the reduction.

   

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  Once the talonavicular joint is reduced, a smooth 0.062-mm Kirschner wire is placed in a retrograde manner across the joint under direct visualization and confirmed radiographically.

   

  Care should be taken under radiographic visualization to ensure the anteroposterior talocalcaneal angle has been reduced as well correcting the hindfoot valgus.

   

  The wire is buried to prevent it from backing out.

   

  Once the talonavicular joint is stabilized, a tenotomy is done of the tendo Achilles to correct residual equinus.

   

  A long-leg cast is applied with the ankle and forefoot in a neutral position.

• One-Stage Extensive Soft Tissue Release

   

  Patient is positioned supine on a radiolucent table and tourniquet is placed on the proximal thigh.

   

   

  An extensive dorsolateral approach is used to perform a talonavicular capsulotomy and lengthening of the tibialis anterior tendon, extensor digitorum longus, and peroneal tendons.16, 18, 21, 22, 23 Capsulotomies of the subtalar joint both medially and laterally.

   

  A posterior incision is performed next to lengthen the Achilles tendon and release the posterior subtalar and ankle joints.

   

  The talonavicular joint is then reduced and held with a Kirschner wire.

   

   

  The calcaneocuboid joint is released if subluxation of this joint is still present. This is also held reduced with a Kirschner wire.

   

  PEARLS AND PITFALLS
  	Localizing ▪ The talar head in vertical talus is located plantar medially and can be difficult to the talar palpate in an infant's foot. If the distal medial calcaneus is used as the fulcrum head instead of the head of the talus, the correction will not be achieved.     Importance ▪ A position of maximal equinovarus (clinically looks like clubfoot) must be achieved of in the last cast prior to pin fixation of the talonavicular joint. This is analogous to

   

  equinovarus achieving 70 degrees of external rotation in the final clubfoot cast using the Ponseti method.

  • Failure to do so will result in an incomplete reduction of the talonavicular joint and a failure to adequately stretch the contracted dorsolateral soft tissue structures placing the patient at a higher risk of early relapse.

 

Treatment timing

• Begin treatment in the newborn stage if possible. Just as for clubfoot casting, treatment should be initiated at young age to take advantage of the more pliable soft tissues.

   

  Approach ▪ In some stiffer syndromic patients in whom gaining maximal equinovarus positioning is difficult, a small dorsolateral incision is made rather than the dorsomedial incision to allow access to the tighter anterolateral subtalar joint capsule to complete reduction.

  • Approaching the anteromedial subtalar joint capsule in this group of patients may not be enough to gain complete reduction of the talonavicular joint—the anterolateral subtalar joint is more contracted in this patient group and release at this level gives better results.

 

Tendon transfer

• For patients older than 2 years at time of treatment, adding transfer of the tibialis anterior tendon to the neck of the talus should be considered to minimize risk of relapse.

• The tendon is sutured directly into the neck of the talus and approached through the same dorsomedial skin incision used for pin placement.

   

  Casting ▪ Do not touch the calcaneus at all during the serial casting portion of treatment or it will be blocked from correction from valgus to varus.

  • This is the same principle followed in the Ponseti method where touching the calcaneus prevents it from correcting from varus to valgus.

     

    Avoiding relapse

• Use shoe and bar dynamic bracing as prescribed to minimize risk of relapse. Failure to do so result in increased risk of relapse.

 

 

 

POSTOPERATIVE CARE

 

 

The cast is changed 2 weeks postoperatively to manipulate the ankle to 10 degrees of dorsiflexion. The pin is removed in the operating room at 6 weeks from the index procedure.

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The patient is placed in a dynamic shoe and bar brace system, which they are to wear 23 hours a day for 2 months and then at nighttime for 2 years to prevent relapse (FIG 3).

 

The shoes on the brace are set pointing ahead to stretch the peroneal tendons. The dynamic bar allows active motion at the knees and ankles and also encourages active plantarflexion stretching of the dorsolateral soft tissues.

 

Follow-up is at 1 month after initiating brace wear and then every 3 months for the first 2 years. After that, follow-up is yearly for several years and then every 2 years until the age of 8 years.

OUTCOMES

Treatment with the Dobbs method has been shown in multiple studies from around the world to allow excellent clinical and radiographic (FIG 4) correction in by isolated and nonisolated (syndromic and neuromuscular) cases.

A recent study comparing the Dobbs method with traditional extensive soft tissue release surgery demonstrated that while both methods achieve good radiographic correction, the Dobbs method provides superior clinical and functional results as measured in better subtalar and ankle range of motion and less pain with growth.

 

 

 

 

COMPLICATIONS

Dobbs method

Skin complications from casting

Kirschner wire back out from soft cartilaginous structures Difficulties with postoperative bracing

Extensive soft tissue release Avascular necrosis of talus Wound dehiscence

Undercorrection

Overcorrection

Ankle and subtalar joint stiffness Vascular and neurologic injuries

 

FIG 3 • Dynamic shoe and bar system used to maintain correction of the vertical talus that was achieved with casting and minimally invasive surgery.

 

 

 

FIG 4 • A. Clinical photograph of patient with bilateral vertical talus 10 years after correction with the Dobbs method. B,C. Anteroposterior and lateral radiographs, respectively, of the patient's left foot, demonstrating maintenance of excellent correction.

 

REFERENCES

1. Alaee F, Boehm S, Dobbs MB. A new approach to the treatment of congenital vertical talus. J Child Orthop 2007;1:165-174.

    

    

2. Aslani H, Sadigi A, Tabrizi A, et al. Primary outcomes of the congenital vertical talus correction using the Dobbs method of serial casting and limited surgery. J Child Orthop 2012;6:307-311.

    

    

3. Aydin A, Atmaca H, Müezzinoglu US. Bilateral congenital vertical talus with severe lower extremity external rotational deformity: treated by reverse Ponseti technique. Foot 2012;22:252-254.

    

    

4. Bhaskar A. Congenital vertical talus: treatment by reverse Ponseti technique. Indian J Orthop 2008;42:347-350.

    

    

5. Chalayon O, Adams A, Dobbs MB. Minimally invasive approach for the treatment of non-isolated congenital vertical talus. J Bone Joint Surg Am 2012;94:e73.

    

    

6. Coleman SS, Stelling FH III, Jarrett J. Pathomechanics and treatment of congenital vertical talus. Clin Orthop Relat Res 1970;70: 62-72.

    

    

7. David MG. Simultaneous correction of congenital vertical talus and talipes equinovarus using the Ponseti method. J Foot Ankle Surg 2011;50:494-497.

    

    

8. Dobbs MB, Gurnett CA, Pierce B, et al. HOXD10 M319K mutation in a family with isolated congenital vertical talus. J Orthop Res 2006;24:448-453.

    

    

9. Dobbs MB, Gurnett CA, Robarge J, et al. Variable hand and foot abnormalities in family with congenital vertical talus and CDMP-1 gene mutation. J Orthop Res 2005;23:1490-144.

    

    

10. Dobbs MB, Purcell DB, Nunley R, et al. Early results of a new method of treatment for idiopathic congenital vertical talus. J Bone Joint Surg Am 2006;88:1192-1200.

     

     

11. Dobbs MB, Purcell DB, Nunley R, et al. Early results of a new method of treatment for idiopathic congenital vertical talus. Surgical technique. J Bone Joint Surg Am 2007;89(suppl 2, pt 1):111-121.

     

     

12. Drennan JC. Congenital vertical talus. Instr Course Lect 1996;45: 315-322.

     

     

13. Eberhardt O, Fernandez FF, Wirth T. Treatment of vertical talus with the Dobbs method [in German]. Z Orthop Unfall 2011;149: 219-224.

     

     

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14. Eberhardt O, Fernandez FF, Wirth T. The talar axis-first metatarsal base angle in CVT treatment: a comparison of idiopathic and non-idiopathic cases treated with the Dobbs method. J Child Orthop 2012;6:491-496.

     

     

15. Eberhardt O,Wirth T, Fernandez FF. Minimally invasive treatment of congenital foot deformities in infants: new findings and midterm-results [in German]. Orthopade 2013;42:1001-1007.

     

     

16. Hamanishi C. Congenital vertical talus: classification with 69 cases and new measurement system. J Pediatr Orthop 1984;4:318-326.

     

     

17. Kruse L, Gurnett CA, Hootnick D, et al. Magnetic resonance angiography in clubfoot and vertical talus: a feasibility study. Clin Orthop Relat Res 2009;467:1250-1255.

     

     

18. Mathew PG, Sponer P, Karpas K, et al. Mid-term results of one-stage surgical correction of congenital vertical talus. Bratisl Lek Listy 2009;110:390-393.

     

     

19. Merrill LJ, Gurnett CA, Connolly AM, et al. Skeletal muscle abnormalities and genetic factors related to vertical talus. Clin Orthop Relat Res 2011;469:1167-1174.

     

     

20. Rodriguez N, Choung DJ, Dobbs MB. Rigid pediatric pes planovalgus: conservative and surgical treatment options. Clin Podiatr Med Surg 2010;27:79-92.

     

     

21. Seimon LP. Surgical correction of congenital vertical talus under the age of 2 years. J Pediatr Orthop 1987;7:405-411.

     

     

22. Stricker SJ, Rosen E. Early one-stage reconstruction of congenital vertical talus. Foot Ankle Int 1997;18:535-543.

     

     

23. Zorer G, Bagatur AE, Dogan A. Single stage surgical correction of congenital vertical talus by complete subtalar release and peritalar reduction by using the Cincinnati incision. J Pediatr Orthop B 2002;11:60-67.