EFFECTS OF INTERMITTENT ADMINISTRATION OF PAMIDRONATE ON THE MECHANICAL-PROPERTIES OF CANINE CORTICAL AND TRABECULAR BONE

The mechanical properties of cortical and trabecular bones from beagle s treated with the bisphosphonate pamidronate (administered intermitte ntly 1 week every month for 3 months, at a dosage of O.45 mu mol/kg/da y) were assessed. The mechanical properties of cortical bone were meas ured by four-point bending tests on femoral quadrants, in order to mea sure their elastic modulus and ultimate stress. The structural propert ies of whole tibias were measured in torsion to determine the torsiona l stiffness and failure torque. The elastic modulus and maximum compre ssive stress of the trabecular bone samples were measured by compressi on tests of trabecular cores. Intermittent treatment with pamidronate did not change the pattern of mechanical properties that occurs natura lly around the femur or the torsional stiffness and failure torque of the tibias. By contrast, pamidronate did significantly increase the mo dulus of elasticity (by 19%) and maximum compressive stress (by 33%) o f vertically aligned cylindrical trabecular specimens taken from the v ertebrae of the beagles.