Treatment of the Triphalangeal Thumb

Abstract

Triphalangeal thumb is a thumb with 3 phalanges and has an estimated incidence of 1 in 25,000 live births. Clinical presentation of triphalangeal thumb can vary considerably. Most strikingly is the long finger-like thumb with clinodactyly, in the same plane as the fingers and may or may not present with an extra thumb. Anatomically, the extra phalanx can have different shapes, from wedge to rectangular. Furthermore, the involved joints, ligaments, muscles, and tendons of the first ray, from distal interphalangeal joint to radiocarpal joint, can be hypoplastic, malformed, or absent with varying degrees of stiffness or instability. Also, the first web can be insufficient, and radial polydactyly as well as other hand deformities can be present. The aim of surgical treatment is to try to reconstruct or correct the anatomic difference and at the same time provide a more acceptable appearance. In our series, depending on the malformation, operations varied from removal of the delta phalanx with ligament reconstruction to multiple osteotomies and rebalancing as well as pollicization. Complications are mostly related to structures that have not been reconstructed or corrected during operation. Results in these often complex cases can be rewarding if the surgeon has sufficient knowledge of the underlying anatomic differences.