synonyms: congenital convex pes valgus, CVT, congenital vertical talus, congenital rigid rocker bottom foot, flatfoot, Persian slipper, dislocated navicular, oblique talus
- 754.7 Talipes, unspecified Congenital deformity of foot NOS
CVT Etiology / Epidemiology / Natural History
- Irreducible dorsal dislocation of the navicular on the talus with a fixed equinous hindfoot deformity (rigid rockerbottom flatfoot).
- Etiology unknown; frequently associated with neuromuscular disorders.
- 50% have associated disorders: spina bifida, chormosolmal abnormalities, myeloarthropathies, neurologic disorders, arthrogryposis, myelomeningocelle, sacral agenesis.
- 50% bilateral.
- extensor tendons and heel cord are contracted, causing talar head to be planter flexed into sole of foot.
- See also Foot anatomy.
CVT Clinical Evaluation
- Rigid flatfoot with a rockerbottom appearance. May have calluses under the head of the talus. The foot has a convex deformity with a prominent head of the talus plantarmedially
- Talar head is prominent medially. Sole of the foot is convex. Forefoot is abducted and dorsiflexed, hindfoot equinovalgus.
- Peg-leg gait (limited forefoot push-off).
- The anterior aspect of the plantar-flexed calcaneus is responsible for the convex bulge of the sole creating the rocker-bottom deformity.
- Thorough neurologic examination and imaging indicated
CVT Xray / Diagnositc Tests
- Weightbearing anteroposterior and lateral views of the foot demonstrate the navicular dorsally dislocated on the talus.
- Lateral view:Long axis of the 1st metatarsal does not line up with the long axis of the talus. Lateral xray shows talus is vertical. Stressed planter flexion lateral view talus remains vertical and does not line up with navicular/forefoot as it should. Calcaneus is in equinus, and forefoot displaced dorsally on the talus.Navicular may dislocate anterosuperiorly to the neck of the talus, calcaneocuboid may also dislocate
- A/P veiw: talocalcaneal angle >40° (normal 20-40°).
- Lateral maximum plantarflexion view: line along long axis of talus passes below the long axis of the 1st metatarsal-cuneiform. If the navicular reduces with maximal plantarflexion it is an oblique talus, and best treated with TAL and orthotics. CVT is confirmed when the lateral maximum plantarflexion view demonstrates that the dislocation of the navicular on the talus is a fixed defomity.
- The navicular does not ossify until age 3 years, but it can be inferred that it is dislocated dorsally by the position of the forefoot
- Lateral maximum dorsiflexion view: demonstrates fixed plantar flexion of the talus.
CVT Classification / Treatment
- Pediatric geneticis consult indicated to evaluate for associated genetic disorders.
- Initial treatment: Serial casting in plantarflexion, supination and hindfoot varus stretches the talonavicular joint in order to facilitate its reduction. Long leg cast with the knee flexed 90° to prevent cast slippage. Weekly follow-up and cast changes.
- Surgery: generally required; talonavicular joint reconstruction with Achilles tendon lengthening generally performed at 6-18months old. Consider naviculaectomy for recurrent deformity or untreated older children. Resistant cases may require talectomy, subtalar arthrodesis or triple arthrodesis.
- Oblique Talus: Talonavicular subluxation which reduces with foot plantar flexion. Generally treated with observation. Consider UCBL shoe inserts or percuaneous pinning of the talonavicular joint in the reduced position with tendoachilles lengthening.
CVT Associated Injuries / Differential Diagnosis
- Wound breakdown
- Undercorrection / overcorrection
- AVN of the talus
- Loss of foot and ankle ROM
- Nerve injury
CVT Follow-up Care
- Follow-up care varies and is dependent on surgical procedure performed.
- Outcome good in 60-80%
- Majority of pts have stiff but functional hindfoot
- 10% remain painful
CVT Review References