# Pediatric Thumb Reconstruction ## Introduction Pediatric thumb reconstruction focuses on restoring thumb position, stability, and function in children with congenital or postnatal deficiencies. This guide reviews stepwise surgical principles, soft-tissue releases, tendon transfers, skin coverage options, and joint procedures used to improve thumb abduction, extension, and prehension. Practical examples and decision points are provided to help learners understand indications and expected outcomes. > Definition: Pediatric thumb reconstruction is the set of surgical and soft-tissue procedures aimed at restoring thumb position, motion, and grasp in children with congenital absence, hypoplasia, or deformity of thumb structures. ## Overview: Goals and Principles - Restore thumb opposition, abduction, and extension sufficient for prehension - Preserve growth plates (physes) whenever possible - Use local tissues first, then tendon transfers or joint procedures as needed - Protect neurovascular structures during releases and transfers ## Key Anatomic Structures to Consider - Thenar muscles (abductor pollicis brevis, opponens pollicis, flexor pollicis brevis) - Adductor pollicis (transverse and oblique heads) - Extrinsic tendons: flexor pollicis longus (FPL), extensor pollicis brevis (EPB), extensor pollicis longus (EPL) - Donor tendons for transfer: extensor indicis proprius (EIP), extensor digiti minimi (EDM), slips of extensor digitorum communis (EDC), flexor digitorum superficialis (FDS) - Superficial palmar fascia and transverse carpal ligament ## Assessment and Decision-Making 1. Determine which structures are absent, hypoplastic, or contracted: skin planes, intrinsic thenar muscles, extrinsic tendons, joint alignment. 2. Address soft-tissue contractures first (skin and intrinsic origins). If joint deformity persists and prevents functional position, proceed to joint procedures such as chondrodesis or arthrodesis while preserving physes when possible. 3. Plan tendon transfers when extensor or flexor continuity is absent and function is inadequate after release. ### Practical example A child has limited thumb abduction with tight thenar origin and deficient EPB. First perform release of the thenar origins to restore passive abduction and extension; if active extension remains insufficient and EPB is absent, plan an EIP transfer to reconstruct thumb extension. ## Thenar and Adductor Muscle Origin Release (Intrinsic Muscle Contracture) - Indication: Tight thenar and adductor origins that draw the thumb metacarpal into the palm, limiting abduction/extension. - Approach: Palmar incision paralleling the thenar crease - Steps: 1. Release palmar fascia and fibrous thenar origins from transverse carpal ligament 2. Identify and protect palmar cutaneous branch of the median nerve and the thenar motor (recurrent) branch 3. Dissect the muscle origins of short abductor and flexor pollicis brevis from transverse carpal ligament, leaving ligament intact when possible 4. Retract FPL tendon to reach deep fibers of short flexor and opponens 5. Release transverse head of adductor pollicis from 3rd metacarpal periosteum; visualize and protect deep palmar arch and terminal ulnar nerve branch between adductor heads 6. Repeat for oblique head if needed - Advantages: - Preserves muscle insertions (maintains MP joint stability) - Preserves innervation so muscles remain functional from advanced origins - Wound management: small palmar defect can be covered by a transposed index-finger flap or left to heal secondarily; skin grafting usually unnecessary > Definition: Chondrodesis is a form of growth-preserving joint fusion where the physis of the proximal phalanx is preserved while stabilizing the metacarpophalangeal joint in extension. ## Skin Coverage and Webspace Reconstruction - Skin deficiency may be in one plane (webspace) or both webspace and palmar (flexion plane). - For single-plane web deficiency: single- or four-flap Z-pl