Congenital anomalies of the hand: an overview.

Of the 1% to 2% of newborns that are born with congenital defects, 10% of these are born with upper extremity malformations. Although many classification systems have been developed, the most widely used classification system was developed by Swanson. This system categorizes the congenital upper extremity malformations according to the embryonic process that has failed to develop. Congenital hand malformation is a broad category that is broken down into 7 subclasses. This review will focus on congenital hand defects and their associated craniofacial syndromes. The topics will include failure of formation, failure of differentiation, duplication, overgrowth, undergrowth, constriction band syndromes, and generalized skeletal abnormalities.