The value of simple morphometric techniques in the diagnosis of osteoporosis

In order to assess the value of simple morphometric methods in the diagnosis of osteoporosis we measured trabecular bone volume (TBV), trabecular number per unit area and relative osteoid volume in two separate iliac crest biopsies in 20 patients with conclusive autopsy evidence of osteoporosis and 20 controls. In osteoporotic patients trabecular bone volume ranged between 3.0-19.2% (median 10.7%) in the anterior and 3.0-14.3% (median 9.7%) in the posterior biopsy and in controls between 2.5-24.8% (median 13.5%) in the anterior and 5.8-25% (median 12.4%) in the posterior. Trabecular numbers in osteoporotic patients ranged from 1.7-8.3/10 mm2 (median 3.5) and in controls 1.6-17/10 mm2 (median 5.63). Relative osteoid volume showed a similarly wide range. In adjacent biopsies trabecular bone volume and trabecular number could differ by as much as 100% and this casts doubt on the value of sequential bone biopsies in the management of individual patients. We conclude that simple morphometric techniques cannot accurately diagnose osteoporosis. However, if the TBV is greater than 18% osteoporosis is unlikely to be present (upper 95% confidence limit = 17.8%). However, a low value for TBV is not diagnostic for osteoporosis because of a large overlap between control and osteoporotic groups.