Bending resistance at hip and fractures risk in postmenopausal women independent of bone mineral density

Several studies suggest that aging loss of bone mass is not necessarily associated with reduced mechanical proprieties as bending resistance. Since postmenopausal women with fracture and without osteoporosis might have an impairment in the bending mechanisms at hip, our aim was to assess if women with and without fractures differ in the femoral parameters of resistance to bending, independent of the bone loss. In this cross-sectional study we enrolled 192 postmenopausal women who underwent X-ray absorptiometry scan to measure bone mineral density as well as cross-sectional geometry parameters at the hip (Hip structure analysis). Among women with osteoporosis, a higher odds ratio for fracture was found in the first tertile of NN-Dmax, a parameter linked to the resistance to bending forces in a cross-section (tertile I, OR = 6.7, p = 0.03; CI 1.19–38.01; reference tertile III). We also found a significantly higher risk for major fracture in the first tertile of NN-Dmax (tertile I, OR = 6.0, p = 0.02; CI 1.26−28.4; reference tertile III). Among women without osteoporosis, a significantly higher odds ratio for fracture was found in the first tertile of IT-CSA, a parameter of resistance to axial load (tertile I, OR = 7.2, p = 0.002; CI 2.04–25.9; reference tertile III). We also found a significantly higher risk for major fracture in the first tertile of IT-CSA (OR = 18.4, p = 0.001; CI 1.52−221.8; tertile III reference). We demonstrate that some hip structural parameters are independently associated to the fracture risk in postmenopausal women.