Congenital Vertical Talus

A rigid, irreducible talonavicular dislocation is the hallmark of CVT. Contractures of the tendo Achillis 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. ^[5] 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.

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. ^[6]

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 ^[7] :

• 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. ^[8] 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.

CVT is an uncommon disorder. Jacobsen and Crawford reported only 273 cases. ^[9] Some have estimated the incidence of CVT to be one tenth that of congenital clubfoot.

In general, with proper treatment, the outcome and prognosis are good. ^{[10, 11, 12]} 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. ^{[5, 13, 14]} 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. ^[7] Kodros and Dias published results they derived using a single-stage approach with a Cincinnati incision. ^[15]

Seimon described a single-stage dorsal approach in which the EHL and the peroneus tertius were tenotomized and the talonavicular joint was opened. ^[6] 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. ^{[16, 17]}

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. ^[4] 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. ^[10]

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]

Cummings and Hooseinzadah reported their results of treating 47 feet with the Dobbs method. ^[23] They found more recurrences if treatment was started after age 12 months.