Clinical Effects of Distal Phalanges and Nail Bed Fusion in Type III Thumb Duplication.

Background: This study aimed to investigate the clinical effects of bone fusion distal to the phalangeal epiphyseal plate in treating asymmetrical type III thumb polydactyly, focusing on growth and scar healing.

Methods: In patients with asymmetrical type III thumb syndactyly, the proximal phalanx of the accessory finger, distal epiphyseal plate, and some soft tissue were excised to create a pedicled tissue flap. This flap, containing part of the nail and bone distal to the epiphyseal plate, was subsequently attached to the distal segment of the main finger. The therapeutic effect was evaluated during follow-up.

Results: Ten children (6 boys and 4 girls) were included, with follow-up periods ranging from 24 to 60 months. All parents expressed satisfaction with the appearance and function of reconstructed thumbs. All reconstructed thumbs utilizing pedicled composite tissue flaps survived without arteriovenous crises, and there were no instances of perioperative mortality or wound infection. Compared with the contralateral normal thumb, most reconstructed thumbs exhibited good alignment and similar length and circumference. The reconstructed nails demonstrated a smooth surface with an appropriate curvature of the nail margin. The interphalangeal (IP) joint remained stable, and no instability of the IP joint collateral ligament was observed. The active and passive ranges of motion of the IP joint were satisfactory, and the epiphyseal plate of the reconstructed thumb was well-developed.

Conclusions: This method is considerably effective in reconstructing asymmetrical type III thumb duplication through fusion of bone distal to the phalangeal epiphyseal plate.