A 4-month-old male infant with bilateral CTEV has been undergoing Ponseti casting since age 1 week. After 8 weeks of serial weekly casting, the feet show good correction of the varus and adduction deformities, but persistent equinus remains. The Achilles tendon is palpably tight. What is the most appropriate next step in management?

Explanation

## Management of Residual Equinus in CTEV — Ponseti Protocol ### Role of Percutaneous Achilles Tenotomy **Key Point:** Persistent equinus deformity after 6–8 weeks of Ponseti casting is a normal part of the protocol and is managed by percutaneous Achilles tenotomy (PAT), not by prolonging casting or resorting to open surgery. ### Indications for Percutaneous Achilles Tenotomy | Finding | Timing | Action | |---------|--------|--------| | Varus and adduction corrected | Week 6–8 | Assess for residual equinus | | Equinus persists | Week 6–8 | Percutaneous Achilles tenotomy | | Dorsiflexion < 10° | Prerequisite | Indicates need for tenotomy | | Palpable tight Achilles tendon | Clinical sign | Confirms need for tenotomy | **High-Yield:** The Ponseti method typically requires percutaneous Achilles tenotomy in 80–90% of cases. This is a minor procedure (can be done under local anesthesia or light sedation) and is integral to the protocol. ### Procedure and Post-operative Management 1. **Percutaneous tenotomy** under local anesthesia or sedation 2. **Final plaster cast** applied for 3 weeks to allow tendon healing in lengthened position 3. **Transition to Denis Browne splint or foot abduction orthosis (FAO)** after cast removal 4. **Long-term splinting** (3–5 years) to prevent relapse **Clinical Pearl:** Percutaneous tenotomy is minimally invasive and has excellent outcomes. The Achilles tendon regenerates and lengthens naturally over 3 weeks of immobilization. ### Why This Is Part of Standard Ponseti Protocol **Mnemonic:** **PACT** — **P**onseti, **A**chilles tenotomy, **C**asting, **T**hen splinting The presence of a tight Achilles tendon and persistent equinus at 8 weeks of casting is an expected finding that indicates the need for tenotomy — not a failure of conservative treatment. ### Why Other Options Are Incorrect - **Option 0 (Continue casting):** Prolonging casting beyond 8 weeks without addressing the tight Achilles tendon will not correct equinus. The tendon must be lengthened. - **Option 2 (Open surgical release):** Open surgery is not indicated at this stage. Percutaneous tenotomy is minimally invasive and highly effective. Open release is reserved for late presentations or recurrent deformities after failed conservative treatment. - **Option 3 (Discontinue casting and physiotherapy):** Stopping casting at 4 months without completing the protocol (tenotomy + final cast) will result in relapse and loss of correction achieved so far.