## Classification of CTEV by Anatomical Type **Key Point:** Posteromedial CTEV accounts for approximately 95% of all congenital talipes equinovarus cases, making it by far the most common variant. ### Anatomical Types and Frequency | Type | Frequency | Characteristics | Clinical Features | |------|-----------|-----------------|-------------------| | **Posteromedial (Varus Equinus)** | ~95% | Inversion + equinus + adduction | Most common, idiopathic | | Posterolateral (Valgus Equinus) | ~3% | Eversion + equinus | Associated with neuromuscular conditions | | Anteromedial (Varus Calcaneus) | ~1% | Inversion + calcaneus | Rare, often iatrogenic | | Anterolateral (Valgus Calcaneus) | <1% | Eversion + calcaneus | Very rare | **High-Yield:** The posteromedial type is the **idiopathic form** — it presents in otherwise healthy infants with no associated syndrome or neuromuscular disorder. The posterior and medial deformities (equinus and varus) are the hallmark features. ### Why Posteromedial is Most Common 1. **Intrauterine position:** Prolonged plantarflexion and inversion in utero mimics the posteromedial deformity. 2. **Genetic predisposition:** Familial clustering suggests autosomal dominant inheritance with incomplete penetrance. 3. **Muscle imbalance theory:** Relative overpull of posterior and medial foot muscles (tibialis posterior, flexor hallucis longus) versus weak anterior/lateral muscles. **Clinical Pearl:** The posteromedial type typically presents in a full-term, otherwise healthy infant with a rigid, inverted, plantarflexed foot. No associated neurological or skeletal abnormalities are present — this is the "pure" idiopathic CTEV. ### Other Types — When to Suspect - **Posterolateral:** Consider neuromuscular disease (cerebral palsy, myelomeningocele, arthrogryposis). - **Anteromedial/Anterolateral:** Rare; may follow overcorrection of posteromedial CTEV or be part of a syndrome (e.g., Freeman-Sheldon syndrome).
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