Assessment of Fracture Risk: Population Association Versus Individual Prediction

Epidemiological transition to mortality and refracture following an initial fracture

This study sought to redefine the concept of fracture risk that includes refracture and mortality, and to transform the risk into "skeletal age". We analysed data obtained from 3521 women and men aged 60 years and older, whose fracture incidence, mortality, and bone mineral density (BMD) have been monitored since 1989. During the 20-year follow-up period, among 632 women and 184 men with a first incident fracture, the risk of sustaining a second fracture was higher in women (36%) than in men (22%), but mortality risk was higher in men (41%) than in women (25%). The increased risk of mortality was not only present with an initial fracture, but was accelerated with refractures. Key predictors of post-fracture mortality were male gender (hazard ratio [HR] 2.4; 95% CI, 1.79–3.21), advancing age (HR 1.67; 1.53–1.83), and lower femoral neck BMD (HR 1.16; 1.01–1.33). A 70-year-old man with a fracture is predicted to have a skeletal age of 75. These results were incorporated into a prediction model to aid patient-doctor discussion about fracture vulnerability and treatment decisions.

In Vivo Assessment of Cortical Bone Fragility

PURPOSE OF REVIEW

This review updates readers on recent developments in the assessment of cortical bone fragility in vivo. The review explains the clinical need that motivated the development of Cortical Bone Mechanics Technology™ (CBMT) as a scientific instrument, its unique capabilities, and its necessary further development as a medical device.

RECENT FINDINGS

Clinical experience with dual-energy X-ray absorptiometry has led to calls for new clinical methods for assessing bone health. CBMT is a noninvasive, dynamic 3-point bending test that makes direct, functional measurements of the mechanical properties of cortical bone in ulnas of living people. Its technical validity in accurate measurements of ulna flexural rigidity and its clinical validity in accurate estimations of quasistatic ulna bending strength have been demonstrated. Because CBMT is a whole bone test, its measurements reflect the influences of bone quantity and bone quality at all hierarchical levels.

Fracture incidence and secular trends between 1989 and 2013 in a population based cohort: The Rotterdam Study

Fracture incidence needs to be evaluated over time to assess the impact of the enlarging population burden of fractures (due to increase in lifespan) and the efficacy of fracture prevention strategies. Therefore, we aimed to evaluate the association of femoral neck bone mineral density (FN-BMD) measured using dual-energy X-ray absorptiometry (DXA) at baseline with fracture risk over a long follow-up time period. Incident non-vertebral fractures were assessed in 14,613 individuals participating in the Rotterdam Study with up to 20 years of follow-up. During a mean follow-up of 10.7 ± 6.2 years, 2971 (20.3%) participants had at least one incident non-vertebral fracture. The risk for any non-vertebral fracture was 1.37 (95% Confidence Interval (CI): 1.25-1.49) and 1.42 (95%CI: 1.35-1.50) for men and women, respectively. The majority (79% in men and 75% in women) of all fractures occurred among participants a normal or osteopenic T-score. The incidence rates per 1000 person-years for the most common fractures were 5.3 [95%CI: 5.0-5.7] for hip, 4.9 [95%CI: 4.6-5.3] for wrist and 2.3 [95%CI: 2.0-2.5] for humerus. To examine the predictive ability of BMD through follow-up time we determined fracture hazard ratios (HR) per standard deviation decrease in femoral neck BMD across five year bins. No differences were observed, with a HR of 2.5 (95%CI: 2.0-3.1) after the first 5 years, and of 1.9 (95%CI: 1.1-3.3) after 20 years. To assess secular trends in fracture incidence at all skeletal sites we compared participants at an age of 70-80 years across two time periods: 1989-2001 (n = 2481, 60% women) and 2001-2013 (n = 2936, 58% women) and found no statistically significant difference (p < 0.05) between fracture incidence rates (i.e., incidence of non-vertebral fractures of 26.4 per 1000 PY [95%CI: 24.4-28.5]) between 1989 and 2001, and of 25.4 per 1000 PY [95%CI: 23.0-28.0] between 2001 and 2013. In conclusion, BMD is still predictive of future fracture over a long period of time. While no secular changes in fractures rates seem to be observed after a decade, the majority of fractures still occur above the osteoporosis threshold, emphasizing the need to improve the screening of osteopenic patients.