Carpal fusions in children of four South African populations

The incidence of carpal fusions was determined from radiographs of both hands of 2,250 Pretoria schoolchildren aged 72 to 191 months. The group included White, Negro, Coloured and Indian subjects. Of the many possible varieties of carpal fusion, only lunato‐triquetral fusion and capitate‐hamate fusion were encountered. No examples of lunato‐triquetral fusion were encountered in children less than ten years of age. In Pretoria Negroes aged 10 to 15 years, the incidence of lunato‐triquetral synostosis is 4.57%, while Pretoria Coloureds show an incidence of 1.51%. This type of fusion was not noted in the White or Indian populations. Two examples of capitate‐hamate synostosis were encountered in Pretoria Negroes. The available evidence suggests that these two varieties of carpal fusion may be added to the list of discrete traits varying in frequency from population to population and probably reflecting different underlying gene frequencies. No significant sex difference in incidence of lunato‐triquetral fusion was noted in the present study. Lunato‐triquetral fusion is about twice as commonly bilateral as unilateral in occurrence.