Review Question - QID 220804

This patient has plain radiographs and a medical history suggestive of congenital vertical talus (CVT); however, calcaneovalgus and an oblique talus need to first be ruled out before formal treatment is determined. Therefore, the next step in this patient would be to obtain a forced plantarflexion radiograph to evaluate if there is persistent dorsal dislocation of the talonavicular joint (answer choice 3).

CVT is a congenital, rigid flatfoot deformity, often (50%) associated with neuromuscular disorders and chromosomal abnormalities. This is a rare deformity with an incidence rate of 1:150,000 births and a 2:1 male-to-female ratio. These neonates present with a prominent talar head and a rigid rocker-bottom foot deformity, including an irreducible dorsolateral navicular dislocation, a vertically oriented talus, and calcaneal eversion with an attenuated spring ligament. Plain radiographs are typically obtained, which will demonstrate a vertical talus and dorsal dislocation of the navicular on a lateral x-ray. A forced plantarflexion lateral radiograph is routinely performed if these findings are present to differentiate CVT from other deformities. In CVT, this forced plantarflexion view will show persistent dorsal dislocation of the talonavicular joint, whereas an oblique talus will reduce. Treatment consists of serial casting with the foot in plantarflexion and supination until the first metatarsal aligns with the talus. Then, they undergo closed versus open reduction of the talonavicular joint with pinning and an Achilles tenotomy.

Cummings et al. performed a retrospective case review of 24 children who underwent a minimally invasive correction of their congenital vertical talus deformity. The mean PROMIS pain interference score was 48±9, the mean PROMIS mobility score was 42±13, and the mean PROMIS peer relations score was 54±9. No significant differences were found in the PROMIS scores between the entire cohort (P >0.05). Treatment after the age of 12 months had lower PROMIS mobility scores compared to those <12 months of age (32.48 vs. 47.31, P =0.02). They conclude that treatment should be initiated in children before 12 months of age to maximize outcomes.

Dobbs et al. retrospectively reviewed 11 patients (19 feet) with CVT who were at least 2 years out from serial casting and surgical management. On average, 5 casts were required for correction before surgical management. At final follow-up, the mean ankle ROM was dorsiflexion: 25 degrees, and plantarflexion: 33 degrees. There was a significant improvement (p< 0.0001) in all of the measured radiographic parameters compared with the pretreatment values. Dorsal navicular subluxation recurred in 3 patients (none had pin fixation of the talonavicular joint). They conclude that serial manipulation and cast immobilization, followed by talonavicular pin fixation and percutaneous tenotomy of the Achilles tendon, provide excellent results in patients with CVT.

Cummings et al. performed a systematic review and meta-analysis comparing the outcomes of children with CVT treated with different methods. They included 31 studies with 580 total feet in this review. The reported incidence of talonavicular subluxation in this study was 19.3% (7.8% requiring reoperation). Radiographic recurrence of the deformity was highest in the direct medial approach (29.3%) and lowest in the single-stage dorsal approach (11%) (p<0.05). They also found the reoperation rate was significantly lower in the single-stage dorsal approach cohort (2%) compared with all other methods (p<0.05). They conclude that the lowest rate of recurrence and reoperation was found with the single-stage dorsal approach; however, future studies need to focus on patient-reported outcomes for further guidance.

Figures A and B are AP and lateral radiographs of a skeletally immature foot demonstrating a vertically oriented talus with dorsal dislocation of the navicular. Figure C is a lateral forced plantarflexion view of the foot demonstrating persistent dorsal dislocation of the talonavicular joint. Illustration A is a lateral forced plantarflexion radiograph demonstrating persistent dorsal dislocation of the talonavicular joint.

Incorrect answer choices:
Answer 1: CVT will not resolve with time, as this is a fixed deformity. If this were calcaneovalgus or an oblique talus, these are typically observed first.
Answer 2: Calcaneovalgus foot positioning can be treated with stretching exercises, not CVT.
Answers 4-5: Serial manipulation/casting, followed by a release and talonavicular reduction and pinning, are used to treat a congenital vertical talus deformity; however, the definitive diagnosis has not been confirmed without a forced plantarflexion view.