Congenital Vertical Talus 

Updated: Jan 25, 2019
Author: Jeffrey D Thomson, MD; Chief Editor: Murali Poduval, MBBS, MS, DNB 

Overview

Background

Congenital vertical talus (CVT) is an uncommon disorder of the foot, manifested as a rigid rocker-bottom flatfoot. Its characteristic radiographic feature is an irreducible and rigid dorsal dislocation of the navicular on the talus. If the navicular is reducible on the lateral maximum plantarflexion radiograph, it is deemed an oblique talus, which is better treated with tendo Achillis lengthening (TAL) and orthotics. If CVT is left untreated, it results in a painful and rigid flatfoot with weak pushoff power. CVT has been referred to in the literature by several synonyms, including congenital convex pes valgus.[1]

Closed treatment, consisting of manipulation and casting, was the earliest form of treatment. Limited surgery was sometimes additionally employed.

Lamy and Weissman recommended excision of the talus, whereas Eyre-Brook advocated excising the navicular.[2, 3] Today, neither of these techniques is accepted as a definitive treatment.

Since about 2006, the trend has been to perform the Dobbs technique when treating CVT. This technique consists of reverse Ponseti-type casting with percutaneous TAL and Kirschner wire (K-wire) fixation of the talonavicular joint.  A limited capsulotomy of the talonavicular joint may be necessary if this joint cannot be reduced in a closed fashion.

Anatomy

A rigid, irreducible talonavicular dislocation is the hallmark of CVT. Contractures of the tendo Achilles posteriorly and the extensor digitorum longus (EDL) and dorsal talonavicular capsule anteriorly are common. In feet with greater involvement or in older children, more contractures and deformity are present (eg, contractures of the tibialis anterior and the extensor hallucis longus [EHL] anteriorly, the peroneus tertius and the inferior retinaculum of the ankle anterolaterally, the peroneus brevis and longus laterally with the calcaneofibular ligament, and the tibiotalar joint posteriorly).

Coleman divided CVT into two types.[4] Type 1 was associated with a calcaneocuboid dislocation, and type 2 was not. This distinction is important clinically because the type 1 deformity is stiffer and particular attention must be paid to releasing the calcaneocuboid joint.

Pathophysiology

The hallmark of CVT is an irreducible and rigid dorsal dislocation of the navicular on the talus. Seimon hypothesized that a contracture of the tendo Achillis posteriorly creates equinus of the calcaneus, with increased verticality of the talus, whereas contracture of the EDL (and sometimes the EHL and the tibialis anterior) pulls the navicular onto the dorsum of the navicular.[5]

Etiology

The etiology of CVT is unknown, but this condition frequently is associated with a wide variety of neuromuscular disorders. Ogata et al proposed a CVT classification system that divides patients into the following three groups[6] :

  • Idiopathic
  • Genetic/syndromic
  • Neuromuscular

Vertical talus is a heterogeneous birth defect resulting from many diverse etiologies. In a study by Merrill et al, based on skeletal muscle biopsies, the most common findings in patients with idiopathic vertical talus were abnormal variations in muscle fiber size and type I muscle fiber smallness.[7] These findings were not specific, but they are common in congenital myopathies and distal arthrogryposis. Whether the biopsy findings are primary or secondary to the joint deformity is unclear.

Epidemiology

CVT is an uncommon disorder. Jacobsen and Crawford reported only 273 cases.[8] Some have estimated the incidence of CVT to be one tenth that of congenital clubfoot.

Prognosis

In general, the outcome and prognosis are good.[9, 10, 11] Some minor calf atrophy and foot size asymmetry occur and are more noticeable in unilateral cases. Ankle range of motion is about 75% of normal. If avascular necrosis (AVN) of the talus occurs, the results are less optimal because of ankle pain, stiffness, and weakness.

Several authors, beginning with Osmond-Clarke, Herndon and Heyman, and Coleman and associates, described staged two-incision reconstructive surgery.[4, 12, 13] The first stage of the Coleman procedure consisted of lengthening the EDL, the EHL, and the tibialis anterior, with capsulotomies of the talonavicular and calcaneocuboid joints and release of the talocalcaneal interosseous ligament. The second stage consisted of TAL and a posterior capsulotomy of the ankle and subtalar joints.

After noting a high incidence of complications with the two-stage technique, Ogata et al recommended a single-stage procedure with a medial approach.[6] Kodros and Dias published results they derived using a single-stage approach with a Cincinnati incision.[14]

Seimon described a single-stage dorsal approach in which the EHL and the peroneus tertius were tenotomized and the talonavicular joint was opened.[5] The talonavicular joint was reduced and held with a K-wire. The Achilles tendon was lengthened percutaneously. Stricker and Rosen published their experience with this technique, as did Mazzocca et al; both groups noted excellent results with few complications.[15, 16]

The trend toward less surgery for CVT continued with Dobbs et al, who published their technique of casting, percutaneous K-wire pinning of the talonavicular joint, and percutaneous heel-cord tenotomy.[17] No patients had extensive soft-tissue releases, though some required lengthening of the tibialis anterior or the peroneus brevis tendon. Casting without pinning of the talonavicular joint was associated with recurrence of deformity.

Saini et al reported on their surgical experience with 20 cases of CVT using a dorsal approach. According to the authors, talonavicular reduction was achieved in all 20 feet, and postoperative talocalcaneal and talo-first metatarsal angles were significantly improved. The results were retained at 4-year follow-up.[9]

Bhaskar described a surgical technique used for idiopathic CVT in four feet; this technique was similar to the Ponseti technique for clubfoot, except that the forces applied were in a reverse direction.[18] The four feet were treated by serial manipulation and casting, tendo Achillis tenotomy, and percutaneous pinning of the talonavicular joint.

To correct the forefoot deformity, four to six plaster cast applications were required.[18] Once the talus and navicular were aligned, percutaneous fixation of the talonavicular joint with a K-wire and percutaneous tendo Achillis tenotomy under anesthesia were performed, followed by application of a cast with the foot in slight dorsiflexion. After treatment, the mean talocalcaneal angle decreased from 70º to 31º, and the mean talar axis–first metatarsal base angle (TAMBA) decreased from 60º to 10.5º.

Wright et al reported on 12 children (21 feet) with idiopathic and teratologic etiologies.[19] They noted 10 recurrences, a rate higher than those cited in other reports. The authors felt that a limited capsulotomy of the talonavicular joint might reduce the risk of recurrence. They did not find a difference in results between the two groups of patients.

In 2012, Chalayon et al reported on 15 consecutive patients (25 feet) with nonisolated CVT who were followed for a minimum of 2 years after reverse Ponseti casting, percutaneous TAL and pin fixation of the talonavicular joint.[20] Five feet required a small medial incision to ensure joint reduction and accurate pin placement, and 20 feet had selective capsulotomies of the talonavicular joint and the anterior aspect of the subtalar joint. Initial correction was obtained in all cases, but recurrence was noted in three patients (five feet).

Patients with CVT have a more favorable prognosis when treated with the Dobbs technique than they do when treated with extensive soft-tissue release. Idiopathic CVT tends to have a more favorable outcome than teratologic CVT does.

Yang and Dobbs published a comparison of the minimally invasive method versus extensive soft-tissue release with a minimum follow-up of 5 years (Dobbs technique). They documented that the minimally invasive method resulted in better results in terms of range of motion and patient-reported outcomes. [21]

Chan et al evaluated the Dobbs method for correction of idiopathic CVT versus correction of teratologic CVT. The results were comparable, but the recurrence rate was slightly higher for teratologic CVT.[22]

 

Presentation

History and Physical Examination

Clinically, congenital vertical talus (CVT) presents as a rigid flatfoot with a rocker-bottom appearance of the foot. The calcaneus is in fixed equinus, and the Achilles tendon is very tight. The hindfoot is in valgus, and the head of the talus is found medially in the sole, creating the rocker-bottom appearance. The forefoot is abducted and dorsiflexed.

The foot is stiff. In ambulatory children, calluses can develop under the head of the talus, which is very prominent along the plantar-medial foot.

Associated genetic syndromes must be excluded; therefore, a consultation with a pediatric geneticist may be indicated.

 

Workup

Imaging Studies

Radiography

Weightbearing anteroposterior (AP) and lateral views of the foot are the first radiographs that must be obtained. A lateral radiograph with the foot in maximum plantarflexion is mandatory to confirm congenital vertical talus (CVT).

Because the navicular may not be ossified, the alignment of the first metatarsal to the talus must be evaluated. In a vertical talus, the metatarsal does not line up with the talus. Lines drawn through the long axis of the first metatarsal and the talus converge on the plantar aspect of the foot. Hamanishi described two radiographic angles: the talar axis–first metatarsal base angle (TAMBA) and the calcaneal axis–first metatarsal base angle (CAMBA).[23] The changing point from a flexible oblique talus to rigid CVT is a TAMBA of approximately 60° and a CAMBA of 20°.

Magnetic resonance imaging

Magnetic resonance imaging (MRI) of the spine may be indicated if an occult spinal dysraphism, such as lipomeningocele, is suspected.[24] Posterior and lateral lumbar spine radiographs also may be useful to exclude occult spinal dysraphism.

Thometz et al evaluated nine patients with CVT using MRI to evaluate the three-dimensional morphologic changes and pathoanatomy. They concluded that there is significant pathology at the level of the subtalar joint.[25]

Ultrasonography

Ultrasonography has been reported to be helpful in distinguishing between CVT (irreducible talonavicular dorsal dislocation) and oblique talus (reducible talonavicular dorsal dislocation).

Histologic Findings

In 2011, Merrill et al published a report evaluating the skeletal muscle abnormalities in CVT.[7] Of note is that their subjects did not constitute a homogenous group: Six of the 11 patients had idiopathic vertical talus, whereas the remaining five had a variety of associated findings. The authors took biopsy samples from the abductor hallucis muscle and found that all patients with CVT had abnormalities. These abnormalities included abnormal variation in muscle fiber size, type I muscle fiber smallness, and abnormal fiber type predominance.

 

Treatment

Approach Considerations

Treatment is indicated when the talonavicular joint is found to be unreducible with maximum plantarflexion. Lateral radiographs of the foot in maximal plantarflexion can reveal if the navicular is reducible. However, radiographs of an infant's foot can be difficult to interpret. The use of dynamic ultrasonography has been reported to be helpful in the evaluation of infants with vertical or oblique talus.[26]

If the talonavicular joint is reducible on the lateral maximum plantarflexion view radiograph, surgery is probably not needed. In these cases, tendo Achillis lengthening (TAL) and orthotics, such as a University of California Berkeley Laboratory (UCBL) orthosis, may be effective.

It is hoped that in the future, the amount of dissection can be minimized, reducing the incidence of avascular necrosis (AVN) and, in turn, improving the overall outcome. Early diagnosis to allow for surgical correction in infants younger than 2 years also should help to improve results.

Controversy exists over the choice of surgical approaches. However, the author believes that the choice of structures to be released is a more important factor in determining outcomes than is the choice of incisions to be used. Special attention must be paid to the dorsal and dorsolateral contracted tissues. Controversy also exists over the need for an anterior tibialis tendon transfer.

Medical Therapy

Serial casting should be the initial treatment, though before the article by Dobbs et al,[17] it was usually thought to be unsuccessful.

Serial casting should be used to stretch the foot in plantarflexion and inversion while counterpressure is applied to the medial aspect of the talus.[18] Elongating and stretching the talonavicular joint in order to facilitate its reduction is important in avoiding compression of the dorsally displaced navicular into the talus. A long leg cast is then applied, with the knee flexed 90° to prevent the cast from slipping. The cast should be changed frequently (about every 1-2 weeks) in order to maximize its effectiveness.

Whereas preoperative casting may be useful for stretching out the dorsal structures, casting rarely is associated with permanent correction.

Surgical Therapy

In the Dobbs technique,[17] if the navicular can be manipulated into the correct alignment relative to the talus, it can then be pinned with a Kirschner wire (K-wire) to maintain the reduction. A small incision can be made over the talonavicular joint, and the joint can be reduced via an open technique if there is any difficulty with the reduction. A percutaneous heel-cord tenotomy is always performed.

The K-wire is left in place for a total of 5 weeks, and the position is held with a long leg cast, which is changed 2 weeks after surgery. A postoperative brace is worn 23 hours per day until walking age, and it is then worn for walking until age 2 years.

A single-stage surgical correction is another option and can be accomplished via either the Cincinnati approach or the dorsal approach. The author generally prefers the dorsal approach, as described by Seimon[5] ; however, the author also prefers the Ollier-type incision. (See the image below.)

Schematic representation of posteromedial release. Schematic representation of posteromedial release.

Operative details

In the author's preferred technique, dissection is performed under tourniquet control, and the superficial peroneal and sural nerves are identified and protected. The author typically finds a contracted peroneus tertius, which is released, as well as an abnormal band of the inferior retinaculum causing a tether from the tibia to the calcaneus. The dorsalis pedis vein and artery and the deep branch of the peroneal nerve are protected, while the tibialis anterior, the extensor hallucis longus (EHL), and the extensor digitorum communis (EDC) are retracted.

The talonavicular joint is visualized and opened dorsally, medially, and laterally. The calcaneocuboid joint also is opened along its dorsal, medial, and lateral aspects. Occasionally, the peroneus longus and brevis must be lengthened. The EHL and EDC can be lengthened, but this is not always necessary. Some advocate transferring the tibialis anterior to the talus.

A percutaneous tendo Achillis tenotomy is performed. The author has not found it to be necessary to perform an open capsulotomy of the tibiotalar (ankle) joint.

A 0.062-in. K-wire is used to hold the talonavicular joint. A talocalcaneal wire typically is not used, nor is it necessary. The author finds it easier to drive the K-wire antegrade into the navicular, through the cuneiform, and out dorsally through the first metatarsal. The talonavicular joint is reduced, and the K-wire is then driven retrograde across the talonavicular joint. The K-wire is cut and buried, and the foot is splinted in a long leg splint for about 10-14 days to allow the swelling to decrease. At that point, the patient is put into a long leg cast, with the ankle in neutral position.

Postoperative Care

The K-wire is removed 8 weeks after surgery, and a walking short leg cast then is used for about 2-4 weeks. The author does not generally use a postoperative brace or orthosis for idiopathic CVT. Postoperative bracing is advised for children with myelodysplasia, arthrogryposis, or other syndromes to maintain correction and prevent recurrence.

Complications

Complications can occur around the time of surgery (perioperatively) or can manifest early or late in the postoperative period.

Common complications in the perioperative period include infection, wound-healing problems, and skin slough; however, these complications are not unique to CVT.

In the first 1-2 years after surgery, the deformity can recur, usually secondary to undercorrection. Undercorrection can occur because of incomplete talonavicular reduction, insufficient posterior ankle release, or residual forefoot abduction.[16] Recurrence of the deformity can also be attributable to neurologic causes, especially in patients with spina bifida. Kodros and Dias reported a high recurrence rate in patients with spina bifida and believed that in these cases the recurrences might be secondary to a tethered spinal cord or other neurologic abnormality.

AVN of the talus is a unique complication of CVT surgery. It was more often reported in the older literature and was associated with the two-stage release and extensive surgery. Subsequent articles by Kodros and Dias,[14] Seimon,[5] Stricker and Rosen,[16] and Mazzocca et al[15] did not report occurrences of AVN of the talus.

Late complications include restricted range of motion of the foot and ankle, which can contribute to calf muscle atrophy. This in turn can lead to easy fatigue of the affected limb.