Vertical talus in a child with chromosomal anomaly

N. MARKEAS, E. VOLONAKIS, P. PAPAGIANNOPOULOS,
G. KATSOULIS, D. PASPARAKIS
2nd Orthopaedic Department, Athens’ Children Hospital “P. and A. Kyriakou”

 

ABSTRACT
Vertical talus is a rare congenital foot deformity that easily becomes apparent immediately after the birth and is appeared as rigid convex pes valgus. The deformity usually appears in association with other congenital or neuromuscular diseases, as the arthrogryposis multiplex congenita, developmental hip dysplasia, myelomeningocele, and Marfan’s syndrome. Chromosomal anomalies are seldom found in the literature. We describe the case of an infant with psychomotor retardation, a peculiar face and deformities in hands (camptodactyly of both indices with ulnar deviation) and feet (rigid convex pes valgus). The examination of chromosomes revealed 46XX, but from one chromosome of the pair 21, the satellites were absent (46XX, 21p-). The vertical talus was treated surgically with lengthening or transferring of tendons, divisions of capsules, and reduction of talonavicular joint. The postoperative result was excellent, clinically and radiographically. We conclude that the cooperation of orthopaedic surgeon with other qualified specialists (paediatrician, genetist etc) is considered essential, because the presence of a chromosomal anomaly in cases with bilateral vertical talus is very possible.

Key words: congenital convex pes valgus, vertical talus, rigid flatfoot, dislocated navicular, chromosomal anomaly.

INTRODUCTION
Vertical talus is an uncommon congenital deformity of the infant’s foot that is manifested as a rigid convex pes valgus. The terms that have been given to the disease (rigid flatfoot, congenital convex pes valgus, dislocated navicular and vertical talus) reveal clearly the embarrassment of the investigators to formulate the true aetiology and pathology that are responsible for the deformity.
The literature includes a little number of papers for cases with vertical talus. They are more related with the description of the surgical techniques for its treatment than its pathology and prevention. The incidence of the disease is unknown, but Osmond - Clarke[1] refers that for every 120 children with congenital talipes varus there is a child with vertical talus. Boys are affected more often than girls[1-6], with up to 71% of cases being bilateral[3].
The mainstay of the deformity is an irreducible (rigid) dorsal dislocation of the navicular on the talus. Seimon[7] hypothesized that a contracture of the tendon Achilles posteriorly creates equinus of the calcaneus, with increased verticality of the talus, while contracture of the extensor digitorum longus (and sometimes the extensor hallucis longus and tibialis anterior) pulls the navicular onto the dorsum of the talus. In older children or in feet with greater involvement, more contractures and deformity are present (e.g., contractures of the peroneus tertius and inferior retinaculum of the ankle anteriorly, peroneus brevis and longus laterally with the calcaneofibular and posterior tibiotalar joints posteriorly[8]).
The vertical talus presents clinically 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 hind foot is in valgus, while the head of the talus is found medially in the sole. The forefoot is abducted and dorsiflexed. Some authors[4] believe that the deformity is rigid at birth, but this theory is not universally accepted[9].
Ogata and associates[10] propose a classification system that divides patients into three groups: idiopathic, genetic / syndromic, and neuromuscular. Chromosomal anomalies have been reported11 in relation to chromosomes 13, 15 and 18. This study describes the case of a child with vertical talus and an anomaly of the chromosomal 21 which appeared a peculiar phenotype.

CASE REPORT
A 9.5 - month - old female infant has been brought in our Department for diagnosis and treatment. She was the third child of healthy parents. She appeared psychomotor retardation, a peculiar face and deformities in hands and feet.
The face appeared hypertelorism, depressed bridge of nose and low - set ears. The physical examination revealed short neck, rhizomelic upper and lower limbs, inverted nipples and joint laxity of wrists and fingers. The index finger of both hands appeared camptodactyly with ulnar deviation. The feet appeared the characteristic deformity of rigid convex pes valgus (figure 1).

Figure 1. The peculiar face and the deformities in hands and feet.

The cardiopulmonary examination didn’t show any pathological findings. Abdominal palpation was without guarding, sensitivity and rebound phenomenon. Liver and spleen were not palpable. The skin didn’t appear any rash. The genitalia were female.
Ultrasound revealed a mild distension of renal pelvis and major calyces of the right kidney. The renal function has been controlled as normal. MRI of brain revealed a dilatation of the posterior cerebellar cisterna and a thin mesalobus.
The microscopic examination of chromosomes revealed 46XX. From one chromosome of the pair 21, the satellites were absent (46XX, 21p-). The rest of genetic examination with the technique FISH, using the special searcher ELN (ONCOR), did not show any pathological findings.
The roentgenographic examination of the feet, through anteroposterior and lateral views (figure 2), showed the vertical talus and the dislocation of the navicular on the dorsal surface of the talus. A lateral radiograph with the foot in maximum plantarflexion did not succeed the reduction of the navicular in its normal position on the anterior (articular) surface of the talus.

Figure 2. The lateral view of radiographs shows the vertical talus
and dislocation of the talonavicular joint.

Foot deformity was treated surgically through three skin incisions: Through the first posterior longitudinal incision (figure 3), a Z - plastic lengthening of Achilles tendon was carried out as well as division of posterior tibiofibular and calcaneofibular ligaments of ankle and posterior capsulotomy of subtalar joint.

Figure 3. Through the posterior longitudinal incision, a Z - plastic lengthening
of Achilles tendon was carried out as well as posterior capsulotomies of ankle and subtalar joints.

The results were good for mobilization of the heel. Through a second lateral incision, a division of capsule on calcaneocuboid joint and a division of bifurcate ligament were carried out for the correction of the foot eversion and the abduction of its front part. Through a third medial incision (figure 4), a division of posterior tibial tendon was carried out as well as a Z - plastic lengthening of anterior tibial tendon, division of extensor digitorum longus and extensor hallucis longus and reduction of talonavicular joint (figure 5). The reduction was maintained with a Kirschner wire through talus, navicular and the first metatarsal. The procedure was completed with resuturing of the posterior tibial tendon to inferior surface of medial cuneiform as well as a careful capsuloplasty and wound closure (figure 6).
The feet were immobilized in the corrected position with long leg casts for 12 weeks after the operation. The K - wire was removed after the first 6 weeks. The clinical and radiological results were excellent.

Figure 4. The medial skin incision.

Figure 5. After the division of posterior tibial tendon was carried out,
the Z - plastic lengthening of anterior tibial tendon and divisions of extensor digitorum longus
and extensor hallucis longus as well as the reduction of talonavicular joint were followed.

Figure 6. The reduction was maintained with a Kirschner wire through talus,
navicular and the first metatarsal.

 

DISCUSSION
Several authors consider that the arthrogryposis multiplex congenita is the commonest cause for the appearance of vertical talus. In a study[12], from 14 patients with the deformity 8 patients (10 feet) suffered from arthrogryposis. However, the deformity is also appeared in children with other congenital (or developmental) diseases or neuromuscular disorders (developmental hip disease, Marfan’s syndrome, and myelomeningocele)11. We seldom find chromosomal anomalies in the literature5. As we know, this is the first time that an anomaly in one chromosome of the pair 21, in association with an obvious vertical talus, is published.
In this point, we consider having interest to report the various classifications with which the investigators tried to explain the complicated relation among different disorders and the deformity. Coleman and associates[13] divide congenital vertical talus into 2 types: type 1 is associated with a calcaneocuboid dislocation, and type 2 is not. This distinction is important clinically, because the feet of the first type are stiffer and need releasing of calcaneocuboid joint for their correction. Another classification[11] distinguishes the feet with vertical talus in 4 groups: supple feet that resemble calcaneovalgus and need radiographs for making the diagnosis (group 1), rigid feet in children suffering from a syndrome (group 2), rigid feet in children with a genetic disorder (group 3), and rigid feet in children suffering from a known neuromuscular problem (group 4).
The clinical findings of vertical talus are classical. However, their diagnostic signs are: a) convex deformity of plantar aspect of foot resembling the rocker - bottom, b) heel in valgus and equinus, c) tight heel cord, d) talar head can be felt on the medial plantar aspect of foot, e) forefoot is abducted and dorsiflexed at the midtarsal joint, and finally f) foot is fixed in this position due to the contractures of soft tissues.

Figure 7. Operative radiography after the reduction of talonavicular joint.

The radiographic examination is made for confirmation of clinical suspicion. Anteroposterior and lateral views are obtained and the alignment of the navicular to the talus is evaluated. Because the navicular may not be ossified and is seldom obvious in radiographs, the alignment of the first metatarsal to the talus must be evaluated. The differential diagnosis between vertical and oblique talus is made using lateral radiographs taken in maximal dorsiflexion and plantarflexion[9]. In a true vertical talus, the navicular (or the first metatarsal) remains on the dorsum of the talus. Hamanishi5 describes 2 radiographic angles: a) the talar axis - first metatarsal base angle (TAMBA) and b) the calcaneal axis - first metatarsal base angle (CAMBA). The changing point from a flexible oblique talus to rigid vertical talus is a TAMBA of approximately 60o and a CAMBA of 20[o].
Magnetic resonance imaging (MRI) of the spine is indicated if an occult spinal dysraphism, such as lipomeningocele, is suspected. For the same reason, posterior and lateral lumbar spine radiographs also may be useful.
In the treatment of vertical talus, a great number of orthopaedic surgeons use successive corrective plasters. Serial casting should be used to stretch the contracted soft tissues in order to facilitate a non - invasive reduction of talonavicular joint. These long leg casts immobilize the knee flexed in 90[o] and should be changed frequently (about every 1-2 weeks) for a period of 3 months. In our case we didn’t use serial casting, because the decision for a treatment was taken when the infant was already 9.5 months old. However, serial casting could be applied for a short preoperative period to stretch out the dorsal structures.
Surgery is indicated when the talonavicular joint is found, after a conservative treatment with serial casts, to be irreducible. The story of various surgical techniques, that have been used, shows the difficulties of the investigators to find out the best one which can correspond to their expectations.
Lamy and Weissman[2] in 1939 recommended excision of the talus, while Eyre - Brook[9] in 1967 advocated excising the navicular. Today, neither of these techniques is accepted as a definitive treatment. Several authors[1,13,14] proposed two - incision reconstructive surgery. The first stage of the procedure includes lengthening of the extensor digitorum longus, the extensor hallucis longus, and the tibialis anterior, with capsulotomies of the talonavicular and calcaneocuboid joints and release of the talocalcaneal interosseous ligament. The second stage includes the tendo - Achilles lengthening and a posterior capsulotomy of the ankle and subtalar joints.
After publishing a high incidence of complications with the 2- stage technique, a single - stage procedure was recommended, either with a medial approach[10] or with a Cincinnati incision[15]. In 1987, Seimon[7] described a single - stage procedure with dorsal approach in which the extensor hallucis longus and peroneus tertius were tenotomized and the talonavicular joint was reduced and held with a Kirschner wire. The Achilles tendon was lengthened percutaneously. Some articles in the next years[16,17] published the experience with this technique and reported excellent results without severe complications.
In a trend toward less surgery for vertical talus, Dobbs and colleagues[18] recommend a technique that includes the non - invasive reduction of navicular into the correct alignment relative to the talus with manipulations and its maintaining with a percutaneous Kirschner wire. If the closed reduction is not feasible, the authors recommend open reduction via a small incision. A percutaneous heel cord tenotomy is always performed. The Kirschner wire is left in place for a total of 5 weeks. A brace is worn postoperatively 23 hours per day until walking age, and then it is worn for walking until the age of 2 years.
In our study, the described technique was the established one that is applied in our Department in cases with vertical talus for more than 20 years. This technique aims releasing of all anatomic structures which are responsible for the deformity. We conclude that with 1) adequate soft tissue release, 2) complete talocalcaneonavicular joint reduction, 3) proper postoperative maintenance of the corrected position, and 4) the physical therapy[12], satisfactory results in the treatment can be achieved. However, we preferred the resuturing of the posterior tibial tendon to inferior surface of medial cuneiform instead of transferring of the tibialis anterior to the neck of the talus[8].
In this study, there hasn’t been satisfactory period of time for postoperative follow - up, because our aim was to intimate the correlation between the deformity of vertical talus and the described chromosomal anomaly, which is uncommon and unknown in Greek and international literature.

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