A 6-month-old male infant with congenital talipes equinovarus underwent Ponseti casting starting at 2 weeks of age. After 8 weeks of serial weekly casts, the cavus and varus deformities have been corrected, but the equinus persists. Passive dorsiflexion of the foot reaches only 5 degrees plantarflexion. What is the next step in management?

Explanation

## Clinical Context: Persistent Equinus After Ponseti Casting **Key Point:** When equinus deformity persists after adequate serial casting (typically 5–7 casts over 5–7 weeks), the Ponseti protocol includes percutaneous Achilles tenotomy as an integral step—not a failure of the method, but a planned refinement. ## Indications for Achilles Tenotomy **High-Yield:** Persistent equinus (dorsiflexion <10 degrees) after 5–7 casts indicates that the Achilles tendon is the limiting structure and requires division. ### Why Tenotomy Works 1. **Mechanism:** The Achilles tendon is the primary restraint to dorsiflexion in CTEV; its division allows the foot to achieve neutral or slight dorsiflexion. 2. **Timing:** Performed at 8–12 weeks of age (this infant is at 6 months, slightly older but still appropriate). 3. **Technique:** Percutaneous division under local anesthesia—a minor procedure with minimal morbidity. 4. **Outcome:** Allows completion of correction with a final cast, avoiding the need for major surgical release [cite:Tuli's Orthopedics 5e Ch 8]. ## Ponseti Protocol for Equinus Correction ```mermaid flowchart TD A[CTEV after 5-7 casts]:::outcome --> B{Equinus corrected?}:::decision B -->|Yes: dorsiflexion ≥10°| C[Proceed to maintenance bracing]:::action B -->|No: dorsiflexion <10°| D[Percutaneous Achilles tenotomy]:::action D --> E[Apply final immobilizing cast]:::action E --> F[Cast removed at 3 weeks]:::action F --> G[Maintenance bracing for 3-4 years]:::action C --> G G --> H[Functional correction maintained]:::outcome ``` **Clinical Pearl:** The final cast after tenotomy is kept in place for 3 weeks (longer than the weekly casts) to allow healing of the tenotomy site while maintaining correction. ## Why Not Other Options? ### Continued Casting (Option A) - Additional weekly casts will not correct equinus if the Achilles is the limiting factor. - Prolonged casting without tenotomy risks tissue maceration and does not address the mechanical block. ### Open Surgical Release (Option C) - Reserved for: - Rigid, syndromic CTEV unresponsive to Ponseti + tenotomy - Very late presentations (>6 months) with severe, untreated deformity - Neuromuscular CTEV - Open surgery causes extensive scarring and stiffness; it is not the next step after simple equinus persistence [cite:Tuli's Orthopedics 5e Ch 8]. ### Physiotherapy Alone (Option D) - Stretching and physiotherapy cannot overcome the mechanical block of a tight Achilles tendon. - They are adjuncts to casting and bracing, not primary treatment for persistent equinus.