Surgical outcomes of radial polydactyly according to a modified Wassel-Flatt classification: A retrospective study of 211 patients with 223 thumbs.

We previously introduced the modified Wassel-Flatt classification to overcome the limitation of the traditional classification for radial polydactyly. This study aimed to evaluate this modified classification in terms of surgical planning and clinical outcomes using the Japanese Society for Surgery of the Hand scoring system. A retrospective review of 211 patients with 223 thumbs treated for radial polydactyly between October 2017 and November 2022 was conducted. Patients were classified using the modified Wassel-Flatt classification, which further differentiated between hypoplastic proximal (HP) and hypoplastic distal (HD) types. The results indicated that simple excision was feasible only for the HP type, while the HD type and non-hypoplastic types required more complex procedures. In addition, hypoplastic types generally had better outcomes, with the HP type achieving better appearance scores than the HD type. Comparisons among non-hypoplastic types revealed no significant differences. The modified Wassel-Flatt classification appears to enhance surgical planning and predict clinical outcomes effectively.Level of evidence: IV.