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.
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.
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.