Intraoperative Observation of the Proper Digital Nerves in Wassel-Flatt Type â £ Radial Polydactyly.

PURPOSE: The aim of the study was to present the intraoperative findings of the relevant digital nerves of the duplicated thumbs in an excision and reconstruction procedure for the Wassel-Flatt type Ⅳ radial polydactyly. METHODS: The study was conducted on patients with Wassel-Flatt type IV radial polydactyly who underwent excision and reconstruction between 2018 and 2021 at our institution. The ulnar digital nerve of the radial thumb and the radial digital nerve of the ulnar thumb were identified and traced intraoperatively. The level of the bifurcation of the nerves and abnormal findings were documented. RESULTS: A total of 123 hands in 119 patients were included in this study. In 114 hands, the bifurcation of the nerves was located within 1 cm of the metacarpophalangeal flexion crease. The radial digital nerve to the ulnar thumb was abnormally compressed in deep fascial tissue in 7 of these 114 hands. In 5 hands, the level of bifurcation was more than 1 cm proximal to the crease. No radial digital nerve to the ulnar thumb was identified in the remaining 4 hands. CONCLUSIONS: Although rare, abnormal nerve compression of the digital nerve may exist in duplicated thumbs of Wassel-Flatt type IV radial polydactyly. CLINICAL RELEVANCE: In an excision and reconstruction procedure, we suggest that the bifurcation of the nerves should be identified before the nerve to the radial thumb is excised to avoid injuring the nerve to the main ulnar thumb.