Mechanical strength of bone in canine osteoporosis model: Relationship between bone mineral content and bone fragility

The purpose of this study was to clarify the relationship between bone mineral content (BMC) and mechanical strength in beagle dog models, and to find whether the mechanical strength changed with changes in BMC. We used 17 beagle dogs to create an experimental osteoporotic model, dividing them into six groups, based on age and experimental period. Presence and absence of ovariectomy (OVX); and calcium content of the diet. BMC was determined by dual-energy quantitative computed tomography in the lumbar vertebrae, and the mechanical strength of cancellous bone harvested from the lumbar vertebral body and femoral neck was measured. OVX alone did not affect either BMC or mechanical strength. However, when the dogs were ovariectomized, and then given a reduced calcium diet, the mechanical strength of the femoral neck decreased in parallel with the cortical BMC of the lumbar vertebrae. The mechanical strength of the vertebral cancellous bone was not decreased when the BMC was reduced by 20%, but was decreased when BMC was reduced by 30%.