The carpal bones in congenital hand anomalies: a radiographic study in patients older than ten years.

Abnormalities of the carpal bones in 192 anomalous hands of 154 patients older than 10 years were examined. Judging from the time of appearance of the pisiform, there was no delay of carpal bone maturation in these anomalies. There were differences between the carpal bones of three distinct groups: which included central polydactyly, syndactyly, and typical cleft hand; the group which included radial and ulnar deficiency, and the group which included symbrachydactyly and transverse defect. This suggests that there were differences between these groups in the timing and degree of injury to the limb bud or the hand plate in the course of development. It is thought that the first group originates from maldistribution of mesenchymal tissue of the limb bud (or of the apical ectodermal ridge), the second group from defects of that tissue, and the last group from defects of the mesenchymal tissue of the hand plate.