Hiroo Uchida

Jul 7, 2023 | frontiersin.org | Hiroo Uchida |Gergo Jozsa |Jianping Wu |Zijing Du

Introduction Congenital thumb duplication is the most common hand abnormality (1). Wassel first defined radial polydactyly and then described its seven types (2). Wassel Type IV is the most common type and is defined as thumb polydactyly that is duplicated at the metacarpophalangeal joint level. Hung et al. (3) proposed the following four subtypes of Wassel Type IV: (A) hypoplastic (12%), (B) ulnar deviated (64%), (C) divergent (15%), and (D) convergent (complex) (9%).