2. Classification of congenital hand abnormalities

Although many classification systems of congenital upper limb abnormalities have been proposed, the International Federation of Societies for Surgery of the Hand has for a long time adopted is to use the system proposed by Swanson in 1976. This classifies seven groups on the basis of abnormal embryogenesis (Figure 10.1). However, given the enormous spectrum of congenital upper limb abnormalities, no system is comprehensive and around 10% do not fit neatly into Swanson’s classification (Ogino et al., 1986).

More recently Oberg, Manske and Tonkin (OMT) have put forward a classification system using dysmorphological terminology, placing conditions in one of three groups: Malformations, Deformations and Dysplasias.

The predominant malformations group is then further subdivided according to whether the whole of the limb is affected or the hand plate alone, and whether the primary insult involves one of the three axes of limb development and patterning or is non-axial (Tonkin, 2015). The IFSSH has now adopted the OMT classification.