A newborn presents with bilateral inversion and plantarflexion of the feet. On clinical examination, the feet cannot be passively dorsiflexed beyond the midline. The parents are counseled about the condition and investigations are planned. Which investigation is most appropriate for confirming the diagnosis and assessing the severity of deformity in congenital talipes equinovarus?

Explanation

## Investigation of Choice in CTEV ### Clinical Context Congenital talipes equinovarus (CTEV) is a common congenital orthopedic condition characterized by inversion, plantarflexion, and adduction of the foot. Diagnosis is primarily clinical, but imaging is essential for assessing severity and guiding treatment. ### Why Plain Radiography is the Gold Standard **Key Point:** Plain radiographs (AP and lateral views of the foot) are the investigation of choice for confirming CTEV diagnosis and assessing severity. **High-Yield:** Plain radiographs allow measurement of: - Talocalcaneal angle (normally 20–40°; reduced in CTEV) - Tibiocalcaneal angle - Talonavicular relationship - Degree of cavus deformity These measurements guide treatment decisions and monitor response to conservative management (Ponseti method). ### Comparison of Imaging Modalities | Investigation | Role in CTEV | Timing | Cost | Radiation | |---|---|---|---|---| | **Plain X-ray** | Gold standard; assess severity; serial monitoring | Initial + follow-up | Low | Minimal | | **Ultrasound** | Useful in prenatal diagnosis and neonates (before ossification); soft tissue detail | Prenatal/early neonatal | Moderate | None | | **MRI** | Reserved for complex/resistant cases; assess soft tissue; pre-operative planning | Late/surgical cases | High | None | | **CT** | Not routinely used; 3D reconstruction in complex deformities | Rarely | Very high | High | ### Clinical Pearl In neonates, ultrasound can be used for early assessment before significant ossification occurs, but plain radiographs remain the standard for ongoing monitoring and severity grading. MRI is reserved for atypical presentations or pre-operative assessment in resistant cases requiring surgical intervention. ### High-Yield Fact The **Pirani score** (clinical) and **Talonavicular coverage angle** (radiographic) are used to assess severity and guide treatment intensity. Serial plain radiographs are essential for monitoring response to Ponseti casting. [cite:Tuli Orthopedics Ch 8]