Polycarpaly and other abnormalities of the wrist in chondroectodermal dysplasia: the Ellis-van Creveld syndrome.

Radiographs of 45 wrists of 23 patients who had chondroectodermal dysplasia (CED) showed variable wrist malformations, which we grouped into eight categories. In each patient, the wrists tended to be similar but seldom identical; in six patients they were sufficiently dissimilar that we classified the malformations in their two wrists into separate categories. A ninth carpal bone was present in the wrists of all patients who were five years old or older (42 of 45 wrists). It was located in the distal row, medial to the hamate bone and proximal to the fifth and sixth metacarpals. A tenth carpal bone was found in six wrists. Unlike the ninth carpal bone, it varied in location. All of the carpal bones were deformed, and two or three separate ossification centers of the hamate were found in some individuals. Fusions between the capitate, the hamate, and the ninth carpal bone were present by the last available examination in 71% of the 45 hands: these included fusions between the capitate and hamate in 7%, between the hamate and the ninth carpal bone in 47%, and between all three bones in 18%.