DETERMINATION OF FEMUR STRUCTURAL-PROPERTIES BY GEOMETRIC AND MATERIAL VARIABLES AS A FUNCTION OF BODY-WEIGHT IN RATS - EVIDENCE OF A SEXUAL DIMORPHISM

Femur diaphyses of male and female Wistar rats were densitometrically and biomechanically assayed. The BMD-dependent material properties wer e better in female than in male bones, but cross-section geometric pro perties were better in male femurs. As a result, mechanical properties of the integrated diaphyses were better in males, but differences dis appeared after statistical adjustment of data to a common body weight. Results evidence a feed-back mechanism locally controlling the strain -dependent bone modelling and the corresponding cross-sectional design as related to bone stiffness, with a set-point adjusted to animal bio mass. A sexual dimorphism of bone biomechanics is also described for t he species.