Objective: With an increasing number of old people in populations an understanding of the determinants of mobility and strength is of paramount importance. The effect/consequens of vertebral fractures and cognitive decline on these parameters is not known. The aim of the study was to investigate possible confounding or interaction of cognitive decline with clinical vertebral fractures (VF) with respect to crucial functions, morbidity and hospitalization.

Material and Methods: Data from the population-based Age, Gene/Environment Susceptibility Reykjavik Study (AGES Reykjavik Study) (n=5371) were used. Three groups were used, not fractured (nFR), other fracture than vertebra (oFR), and vertebral fracture (VF). The effect of VF and cognition on function was measured by Timed Up and Go (TUG), 6 meter walk (6mw), grip- and knee-extension strength. VF status was examined from a verified fracture registry for the study group since midlife. Cognition status was evaluated by a consensus panel using detailed cognitive tests and clinical information.

Results: The prevalence of VF increased with age in both sexes and was higher among women (p< 0.0001). Women had overall worse function than men. The effect of VF on function was similar for both men and women. There was a consistent gradient between the fracture groups in performance for all the function tests, NFR performing best and VF worst. For the 6mw, TUG and knee-extension strength, women with VF did worse than those without VF.

Individuals with previous history of VF required more often hospitalization (OR 2.8.(1.8–4.4)). After median follow up time of 30 months from entry into the study those with fractures were significantly more often hospitalized compared to NFR, oFR HR 1.2(1.1–1.3) p< 0.0001 and VF (HR 1.4 (1.2–1.6), p< 0.0001) and men more so than women. These results were not confounded by prevalent hip fractures. Individuals in the NFR group had the shortest hospital stay and those in the VF group stayed the longest and men significantly longer than women (p< 0.0001).

VF had significantly more back pain, used more analgetics and had more gastrointestinal complaints. This explaines only a small proportion of the excess hospitalization.

Cognitive impairment had an effect on performance but interaction with fractures was not seen.

Conclusion: Individuals with VF are at increased risk of beiing hospitalized and in a need of extended hospital stay. They have bad mobility and strength and need analgetics. Those who were cognitively impaired had even worse function which was independent of the VF.

QCT permits a direct measure of bone and muscle size and assessment of bone/muscle relationship. We have studied cross-sectional QCT variables in mid-thigh as predictors of incidental limb fractures in the AGES-Reykjavik Study, a cohort of 66–96-year-old men (n=2160) and women (n=2385) drawn from an established population based cohort and not taking medications affecting bone metabolism. We used 4-detector Siemens CT system, a single axial section through the right mid-thigh (10 mm slice thickness). The variables included in the Cox’s proportional hazard model were; total cross-sectional cortical area (CSA), derived cortical thickness, shaft BMD, shaft bending strength index (BSI), medullary area and buckling ratio, total cross-sectional muscle and quadriceps area and bone/muscle area ratio. All low trauma limb fractures (including proximal end of femur but excluding toes, foot, hand and finger fractures) during mean 3.5 years of follow-up were validated by medical and radiological records, altogether 170 in women and 61 in men, including 87 hip fractures.

Results: with sex as a confounding variable the most significant risk factor was the buckling ratio (ratio of bone radius to cortical thickness) with more than twofold greater risk in the top compared to the lowest tertile. This variable was mostly independent of muscle area which was however a significant protective factor independent of bone variables. Bone/muscle area ratio and BSI were not significant in multivariate analysis. The area under the ROC curve, using these QCT predictors and age, was 0.70 (CI 0.66–0.73).

We conclude that cortical instability associated with decreasing cortical thickness due to medullary expansion is a significant risk factor for limb fractures including hip fractures in old age. Further knowledge on factors affecting buckling ratio might be of importance in the prevention of these fractures in the elderly.