Congenital hand anomalies, and their association with other congenital abnormalities.

Congenital abnormalities of other parts occurring in patients with congenital abnormalities of the hand were studied. Hands and feet often showed similar anomalies, but there were cases in which the hands and feet had different kinds of deformity. Anomalies of the internal organs were associated with anomalies of the thumb. Cleft lip and palate occurred in combination with syndactyly, split hand, preaxial polydactyly and construction ring syndrome. Combined anomalies may be the result of a genetic or environmental factor interfering with parts developing during the same critical period. The critical period and probable pathogenesis are discussed and the conclusion reached that mesenchymal necrosis, abnormal distribution of mesenchyme and tissue necrosis after mesenchymal condensation may be the pathological changes which lead to abnormal development of the hand.