A 3-month-old infant with congenital talipes equinovarus has been undergoing Ponseti casting for 6 weeks. The parents report that the foot position has improved, but the child now presents with a stiff, plantarflexed foot that does not respond to further casting. The treating orthopedist suspects an atypical or complex CTEV variant. Which investigation would be most appropriate to assess the soft tissue anatomy and plan surgical intervention?

Explanation

## Investigation for Complex/Resistant CTEV ### Clinical Scenario This case describes a CTEV that has failed to respond adequately to conservative (Ponseti) management. In such resistant or atypical cases, detailed soft tissue imaging is required to identify associated abnormalities (e.g., abnormal muscle attachments, intrinsic foot muscle anomalies, or associated neuromuscular conditions) and to guide surgical planning. ### Why MRI is Indicated Here **Key Point:** MRI is the investigation of choice for assessing soft tissue anatomy in resistant CTEV and for pre-operative surgical planning. **High-Yield:** MRI provides: - Detailed visualization of intrinsic foot muscles and tendons - Assessment of muscle attachments and anomalies - Identification of associated neuromuscular abnormalities - 3D spatial relationships for complex deformities - No radiation exposure ### When Each Investigation is Appropriate | Scenario | Investigation | Rationale | |---|---|---| | **Initial diagnosis, routine CTEV** | Plain radiographs | Assess bony anatomy, severity, monitor casting response | | **Prenatal screening** | Ultrasound | Early detection, soft tissue detail before ossification | | **Resistant/atypical CTEV, pre-operative planning** | MRI | Soft tissue detail, muscle anomalies, surgical approach | | **Suspected neuromuscular involvement** | EMG/NCS or MRI | Assess nerve/muscle pathology | ### Clinical Pearl Resistant CTEV (failing Ponseti method by 3–4 months) often indicates: - Atypical muscle attachments - Intrinsic muscle anomalies - Associated neuromuscular disorder - Need for surgical correction MRI is essential before surgery to map the anatomy and plan the approach (e.g., posteromedial release, anterior tibial tendon transfer). ### High-Yield Fact Approximately 5–10% of CTEV cases are resistant to conservative treatment and require surgery. MRI is the imaging modality of choice for these cases because it shows soft tissue detail that plain radiographs cannot provide. [cite:Tuli Orthopedics Ch 8]