Bone density, geometry, and fracture in elderly men.

Bone geometry is a major determinant of the mechanical resistance of bone. Mechanical strength of the vertebrae depends on the cross-sectional area of the vertebral body and on the size of the posterior arch. Smaller bone width is associated with higher risk of stress fracture. A longer femoral neck axis and a more open neck-shaft angle are associated with higher risk of cervical hip fracture. No consistent association between the femoral neck width and the cervical fracture risk was found. Areal bone mineral density (aBMD) is not a good tool for the identification of elderly men with high fracture risk. Fracture risk increases with decreasing aBMD, but only a minority of men who will sustain an osteoporotic fracture are identified by a given threshold of baseline aBMD. Bone width seems to be an independent predictor of the fracture risk in elderly men, and its assessment can improve the prediction of fractures in this population.