Polydactyly

Polydactyly (supernumerary digits) is the presence of one or more extra fingers or toes, occurring in approximately 1 in 1,000 live births. It is classified by position: Preaxial (radial / tibial) polydactyly involves duplication of the thumb or hallux (great toe); Central polydactyly involves duplication of the index, middle, or ring fingers; and Postaxial (ulnar / fibular) polydactyly involves duplication of the little finger or fifth toe — the most common form in Asian and African populations. The duplicated digit ranges from a tiny skin tag with no bony connection (rudimentary, Type A/B) to a fully formed, functional digit with complete phalanges, joints, tendons, and neurovascular bundles (complete, Type D).

The optimal timing for polydactyly excision depends on the type and complexity. Simple rudimentary postaxial polydactyly (a small skin tag) can be ligated neonatally with a suture or excised after 6 months under local anaesthesia. More complex preaxial thumb duplications require formal surgical reconstruction and are optimally performed between 1 and 2 years of age — when the child is old enough for safer general anaesthesia, tissues are large enough for fine microsurgical reconstruction of tendons and collateral ligaments, and surgery is completed before the child begins fine motor skill development and schooling.

The surgical goal is to reconstruct a single, stable, well-aligned, and fully functional digit from the available components of both duplicated fingers. In the Wassel classification of thumb duplications (the most surgically complex type), the dominant, better-formed digit is retained; the smaller is ablated, but its key components — the collateral ligament, thenar muscle insertions, and sometimes articular cartilage — are transferred to reinforce the retained thumb. Long-term results in expert hands demonstrate good pinch strength, normal hand function, and satisfactory cosmetic appearance, though some residual angulation or stiffness may require occupational therapy.

Following polydactyly excision, a well-padded plaster or fibreglass immobilization cast is worn for 3 to 4 weeks to protect the repair and allow ligament, tendon, and bone healing. Once the cast is removed, a custom thermoplastic splint is fabricated by a hand therapist to maintain alignment during active rehabilitation. Hand therapy begins at 4 weeks with passive and active range-of-motion exercises, scar desensitization, and gradual strengthening. In young children, play-based therapy techniques are used. Scar management with silicone and massage begins once wounds are fully healed.