The Diagnosis of Senile Osteoporosis Using a New Bone Density Index

Abstract

An endeavour has been made to assess the Ca content of the cortex of the 4th metacarpal of the nondominant hand by the use of radiographs, together with a calcium sulphate wedge, in a water bath. The resultant radiograph is scanned with a recording microdensitometer and the thickness of calcium sulphate giving an image of equivalent density to the middle of the metacarpal bone is determined. Using a water bath obviates inaccuracies due to soft tissues. The effects of scattered radiation and lack of uniformity of the X-ray beam are minimized by using a very small field and a shallow water bath. The thickness of the cortical bone is measured using a caliper with the Vernier scale. The density equivalent of the bone in millimeters of calcium sulphate is divided by the thickness of cortex to give an index which is considered to be proportional to the degree of calcification of the cortical bone. In people with senile osteoporosis this index was found to be high, not normal as had been expected. This agrees with the stencilled outline of the bones which has been noted in senile osteoporosis and is due to the high density but narrow cortex. It also agrees with the calcification of the Haversian canal system which has been described in senile osteoporosis.