Objective: Ovariectomy and cadmium have been reported as the two main risk factors for osteoporosis. The goal of the this study was to measure and compare the effects of ovariectomy and long term exposure to low levels of cadmium on the biomechanical quality of cortical bone in rats. 
 

Materials and Methods: In this study, twenty-one female rats were separated randomly to three groups: a control group cadmium (Cd), group and an ovariectomy (OVX) group. OVX rats underwent bilateral ovariectomy via ventral incision. Twelve weeks after the ovariectomy, cadmium chloride was administered to rats Cd as intraperitoneal injection of 0.5 mg/kg three times a week for 18 weeks. Bone mineral density was measured using dual energy X-ray absorbtiometry. Cross sectional area of the femoral shaft was evaluated by computerized tomography. Tensile test was performed to measure the maximum load, deformation, energy, ultimate stres, ultimate strain stiffness and toughness of the bone tissue. 
 

Results: In the OVX group, except for the stiffness, all of biomechanical parameters were significantly lower than that of the control group (p<0.05). Biomechanical parameters were reduced in the Cd group in comparison to the controls but this reduction was not significant (p>0.05). Additionally, biomechanical parameters were unchanged in the Cd group when compared to the OVX group. 
 

Conclusion: Even though low levels of cadmium are thought to constitute as a risk factor for osteoporosis by degrading the biomechanical quality of the bone tissue, it is not as serious of a threat as experimental osteoporosis.