Similarities and differences between sexes in regional loss of cortical and trabecular bone in the mid-femoral neck: The AGES-Reykjavik longitudinal study

Abstract

The risk of hip fracture rises rapidly with age, and is notably higher in women. After falls and prior fragility fractures, the main clinically recognized risk factor for hip fracture is reduced bone density. To better understand the extent to which femoral neck density and structure change with age in each sex, we have carried out a longitudinal study in subjects not treated with agents known to influence bone mineral density to investigate changes in regional cortical thickness, as well as cortical and trabecular bone mineral density at the mid-femoral neck. Segmental QCT analysis was used to assess bone measurements in two anatomic sub-regions, the supero-lateral (superior) and infero-medial (inferior). A total of 400 older individuals (100 men and 300 women, aged 66–90 years) who were participants in the AGES-Reykjavik study, were studied. Participants had two QCT scans of the hip over a median follow-up of 5.1 yr. (mean baseline age 74 yr.). Changes in bone values during follow-up were estimated from mixed effects regression models. At baseline women had lower bone values in the superior region than men. At follow-up all bone values were lower in women, except cortical vBMD inferiorly. The relative losses in all bone values estimated in the superior region were substantially (about threefold) and significantly greater compared to those estimated in the inferior region in both sexes. Women lost cortical thickness and cortical vBMD more rapidly than men in both regions; and this was only weakly reflected in total femoral neck DXA-like results. The higher rate of bone loss in women at critical locations may contribute materially to the greater femoral neck fracture incidence among women than men.

Variability in reference point microindentation and recommendations for testing cortical bone: Location, thickness and orientation heterogeneity

“…8c, subchondral thickness within the femoral head varied between 200-1000 mm, typical of healthy femoral head subchondral bone thickness (Treece et al, 2010). Johannesdottir et al, 2013). Further, a negative correlation was observed between cortical bone thickness in the superior lateral region and age (r¼ 0.57, p ¼0.04, see Fig.…”

Association between bone indices assessed by DXA, HR-pQCT and QCT scans in post-menopausal women

“…There was moderate to strong agreement between measuring techniques when assessing the same skeletal site. However, when assessing correlations between central and distal sites, the associations were only For the above-mentioned reasons, 3D images have become important clinical research tools when investigating, e.g., hip and femoral bone structure [5,6], the effects of therapeutic agents [7,8] and age-and sexrelated changes [9,10]. Furthermore, the trabecular bone score (TBS) derived from textural images (by DXA) of the spine is related to microarchitecture and fracture risk [11].…”

Role of cortical bone in hip fracture

“…39 In the Age, Gene, Environment Study, Rejkyavik (AGES Study) population-based cohort study, aging of the individual was associated with loss of FEA-assessed strength 40 of the hip in both stance and falling configurations and thinning of the superior femoral neck cortex. 26 This was more rapid in women than men, while in contrast hip fracture prediction was improved more in men than women. These findings were supported by two case-control studies, 35,41 one suggesting that patchy as well as uniform thinning of the superolateral cortex could promote hip fragility.…”

“…22 In a fall onto the greater trochanter, the superolateral cortex, normally loaded weakly in tension, becomes heavily loaded in compression. Because of its thinness in the elderly, [23][24][25][26][27] this cortex is interesting for its potential to buckle in a sideways fall.…”

“…[24][25][26] This change has a small effect on bending resistance while increasing the risk of buckling or crushing superolaterally. In a sideways fall, an elderly and thinned superolateral cortex taking the full impact load might fracture through either mechanism.…”