Diagnosis of osteoporosis: usefulness of photon absorptiometry at the radius.

The photon-absorption method (Cameron-Sorenson) is commonly used in the diagnosis of osteoporosis to measure bone mineral in appendicular bones. Although this method gives accurate and reproducible results when applied to the distal radius and midradius, separation between osteoporotic patients and age-matched normals was less than satisfactory because of a large overlap. By contrast, a radiographic index based on the pattern of trabecular bone at the proximal femur (Singh index) gave a better separation between the two populations. The Singh index discriminates better, probably because osteoporotic patients have a greater proportion of loss of trabecular bone of the axial skeleton than of cortical bone of the appendicular skeleton.