An absence of structural changes in the proximal femur with osteoporosis.

The hypothesis that osteoporosis occurs not as a preferential loss of the tensile trabeculae but as a general loss of bone was tested by using bone mineral densitometry and an indentation test on dissected proximal femora. As osteoporosis advanced a significantly correlated decrease was found in both bone mineral density and mechanical properties between the principal compressive and tensile trabeculae. The decrease correlated with a decrease in the Singh index. These findings led to the conclusion that a sequential bone loss from the tensile trabeculae to the compressive ones did not occur as Singh reported, but instead a generalized loss of bone mineral in both the tensile and compressive trabeculae supervened. The structural changes, on which the grading system by Singh was based, were not observed in the proximal femur affected by osteoporosis.