Microradiographic aspect on iliac bone tissue in postmenopausal women with and without vertebral crush fractures

Bone mass, microstructure and microconnectivity of cancellous bone tissue, microporosity, and microdensity of cortical bone have been evaluated with an image analysing computer on microradiographs in 34 iliac crest bone biopsies from two individual, paired age-matched groups of postmenopausal women. Group 1 comprised 17 cases without vertebral crush fractures (mean age 66 years, range 45-80 years) and time since menopause 20.5 +/- 11.5 years. The second group were 17 cases with vertebral crush fractures (mean age 67 years, range 48-86 years) and time since menopause 16.5 +/- 7.6 years. No differences were observed either in bone mass or in Parfitt's indices of the microarchitecture of their cancellous bone tissue. However, both groups 1 and 2 were different by the number of the structure elements per 30 mm2 of tissue volume and the trabecular bone pattern factor (TBPF) being higher in group 1 than in group 2 (p < 0.005)--showing a better connectivity of bone network in group 2 with crush vertebral fractures than in group 1. The number of terminus to terminus struts of the trabecular bone pattern is increased in group 1 (p < 0.001). On 7-microns stained sections the active cancellous eroded perimeter (Cn.Oc.Pm/B.Pm) is greater in group 1 than in group 2 (p < 0.02). Therefore, in these two populations with a similar degree of osteopenia, a decrease of trabecular connectivity does not provide an explanation of bone fragility and the occurrence of vertebral crushed fractures.