A 6-month-old boy with congenital talipes equinovarus has completed 8 weeks of Ponseti casting but shows persistent equinus and medial deviation of the midfoot on clinical examination. The treating physician wishes to assess whether the deformity has improved radiographically and determine if surgical intervention is needed. Which imaging modality is most appropriate at this stage?

Explanation

## Serial Radiographic Assessment in CTEV During Conservative Treatment ### Clinical Scenario After 8 weeks of Ponseti casting, radiographic re-assessment is needed to: - Measure improvement in talocalcaneal angle (TCA) and talonavicular angle - Determine if the deformity is correcting adequately - Guide decision to continue casting, add percutaneous tenotomy, or proceed to surgery ### Why Plain Radiographs Remain the Standard **Key Point:** Serial plain radiographs (AP and lateral) are the standard for monitoring response to Ponseti treatment because they directly measure the same angles used for initial severity grading. **High-Yield:** The Dimeglio score and angle measurements are reproducible on plain films: - **Talocalcaneal angle (TCA):** Should improve from <15° toward normal (>25°) - **Talonavicular angle:** Should decrease as adduction corrects - **Tibiocalcaneal angle:** Should increase as equinus corrects ### Comparison of Imaging Modalities at This Stage | Modality | Role in CTEV Monitoring | Timing | |---|---|---| | **Plain radiograph** | Serial angle measurement, treatment response assessment | Every 4–6 weeks during casting | | **3D CT** | Complex anatomy, pre-operative surgical planning | Only if surgery planned | | **MRI** | Soft tissue, associated anomalies, research | Not routine; selected cases | | **Ultrasound** | Early detection, soft tissue; less useful for angle measurement | Prenatal/neonatal; not for follow-up | **Clinical Pearl:** The Ponseti protocol relies on serial radiographs to confirm angle correction. If angles are not improving despite casting, percutaneous Achilles tenotomy or surgical release may be indicated. **Tip:** Do not order advanced imaging (CT, MRI) unless plain films show inadequate correction and surgical planning is imminent. Plain radiographs are sufficient for monitoring and decision-making during conservative therapy. [cite:Campbell's Operative Orthopaedics 13e Ch 31]