## Pathophysiology of CTEV **Key Point:** CTEV is characterized by a fixed deformity in four planes: equinus (plantarflexion), varus (inversion), adduction, and medial rotation. Understanding which anatomical changes occur is essential for diagnosis and treatment. ### Correct Anatomical Features in CTEV The four components of the deformity are: 1. **Equinus**: Plantarflexion of the foot at the ankle joint 2. **Varus**: Inversion of the foot (medial deviation of the heel) 3. **Adduction**: Medial deviation of the forefoot 4. **Medial Rotation**: Internal rotation of the entire foot around the long axis of the tibia ### Structural Changes | Structure | Change | Mechanism | | --- | --- | --- | | Talus | Plantarflexed and inverted | Primary deformity | | Navicular | Medially displaced | Follows talus displacement | | Calcaneus | **Varus (NOT valgus)** | Inverted and medially deviated | | Tibialis posterior | Shortened and tight | Contributes to varus and adduction | | Achilles tendon | Shortened | Contributes to equinus | **High-Yield:** The calcaneus is in **varus**, not valgus. This is a critical distinction. In CTEV, the heel is inverted and medially deviated (varus), whereas in clubfoot variants or other conditions, valgus (lateral deviation) may occur. ### Why Option 2 Is Incorrect The calcaneus assumes a **varus position** (inverted, medially deviated) in CTEV, not a valgus position. Valgus would mean lateral deviation of the heel, which is the opposite of what occurs in this condition. **Clinical Pearl:** Palpation of the medial border of the foot and the position of the heel are key clinical findings. In CTEV, the medial border is convex ("bean-shaped" foot), and the heel is inverted. **Mnemonic:** **CAVE** — Cavus (high arch), Adduction, Varus, Equinus. The calcaneus is part of the varus deformity, not valgus.
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