Wassel Type IV Thumb Duplication A Case Report and Literature Review

Thumb polydactyly, also known as radial polydactyly, is the prevailing manifestation of polydactyly. Its existence has been documented in the hand literature from Digby's initial description in 1645. Preaxial polydactyly, specifically bifid thumb, has been extensively observed, with a frequency ranging from 0.08 to 1.4 per 1000 live births. Traditionally, radial polydactyly is classified into three distinct categories: severe hypoplasia, partial duplication, and entire duplication, which can sometimes be mistaken for pseudo duplication. The classification system developed by Wassel has emerged as the widely accepted standard for the categorization of thumb polydactyly. The classifications of surgical treatment procedures are associated with variations. Thumb duplication is categorized as a "duplication" (group 3) in the International Federation of Societies for Surgery of the Hand (IFSSH)/Swanson classification of congenital malformations of the hand and upper limb. The objective of surgical reconstruction is to achieve a thumb that is both stable and mobile, while also possessing appropriate dimensions and form. The prevailing method of reconstruction often involves the excision of the minor digit followed by the subsequent reconstruction of the major digit. Surgical procedures aim to rectify issues pertaining to deviation, instability, and insufficient dimensions. Moreover, it is worth noting that a significant proportion of instances will necessitate an additional intervention in order to enhance the cosmetic and/or functional result.