The metacarpal index in Jamaican children and adults.

The metacarpal index was measured in radiographs of the hands of 615 male and 667 female Jamaicans aged over two years. The index increased with age from two years to adulthood, and was greater in females than in males, and greater in the left hand than the right hand. Means and standard deviations of the index for the left hand are presented as standards. An index of 9.6 for males and 10.1 for females over the age of 13 years is suggested as the upper limit of normal (three standard deviations above the mean). These standards are higher than those previously reported, and are probably applicable to other black populations outside Jamaica.