Usefulness of assessing bone mineral content of cortical bone in patients with lingering imbalance of bone metabolism

The CT numbers of cortex at the level of 20 cm (CT20) and of spongiosa in the lateral condyle at 2 cm (CT02) proximally from the distal end of the femur, and the bone mineral density of spongiosa in L3 body (BMD), were obtained by QCT. The study included 48 patients with rheumatoid arthritis or chronic renal failure as well as 10 healthy volunteers. The relationships of CT20 vs BMD in the regions above and below a critical value of BMD were quite different from each other. Similar relationships were observed in the plot of CT20 vs CT02. The results indicated that the demineralization of cortex was much less than that of spongiosa while the mineral content of spongiosa kept higher than a critical value, but the demineralization of cortex surpassed that of spongiosa once the mineral content of spongiosa had become lower than the critical value. It is necessary to assess bone mineral content of cortex especially in patients with lingering imbalance of bone metabolism.