A comparative estimation of the combined cortical thickness of various bone sites.

Measurement of the cortical thickness of long bones is the best method of quantitatively diagnosing osteoporosis. Combined cortical thickness (CCT) is as good as, or better than more complicated indices. In osteoporosis studies, the problem lies in finding a physiologically consistent bone site . The CCT of the lower shaft of the humerus showed the lowest coefficient of variation in this homogeneous female population and the addition of both CCT values further reduced the variability. It is suggested that the humeral site is significantly superior to the metacarpal sites and that the variability is small enough to give clinically useful information in the diagnosis of osteoporosis.