Polydactyly

the presence of extra digits in the hand or foot. When present on the radial side of the hand the condition is termed preaxial polydactyly, whereas on the ulnar side of the hand it is known as postaxial polydactyly. Preaxial polydactyly may be associated with other congenital disorders, including acrocephalosyndactyly, brachydactyly B, acropectorovertebral dysplasia, Fanconis syndrome and Holt Oram syndrome; postaxial polydactyly can also occur in conjunction with chondroectodermal dysplasia (Ellis van Creveld syndrome), Laurence Moon Biedl syndrome, trisomy 13 syndrome, Jeunes syndrome and focal dermal hypoplasia (Goltzs syndrome).

An unusual condition termed delta phalanx may be associated with polydactyly. In this condition a longitudinally bracketed epiphysis is seen. The delta phalanx leads to the development of a trapezoid-shaped diaphyseal metaphyseal unit with alterations in physeal configuration.