Bone Microarchitecture and Mechanical Competence Are Associated with Fracture Across Race and Sex in Older Adults

Studies evaluating skeletal differences by fracture status used predominantly White female cohorts with limited data in other races and men. Using high-resolution peripheral quantitative CT and microfinite element analysis, we compared skeletal health by fracture status and assessed the effect of socioeconomic (SE) factors and effect modification by race and sex in a population-based study in New York City. Participants with historical fractures (Fx) included adult fractures (18+ yrs; no digits, skull, face). Of 935 (age 76.1±6.3 yrs, 71% female, 27.7% Black, 29.7% White, 41.3% Mixed), 32% had 444 fractures. Results were adjusted for age, BMI, sex, race, ethnicity, past osteoporosis treatment, and oral glucocorticoid use. At the distal radius, the Fx group had worse trabecular (Tb) and cortical (Ct) parameters with 9.7-10.3% lower failure load (FL) and stiffness (p<0.001). At the distal tibia, results were similar with 5.9% lower FL and stiffness in the Fx group (p<0.001). Adjusting for SE factors, Tb and Ct parameters remained worse in the Fx group with lower FL and stiffness. Stiffness and FL varied by race and sex but were lower in Fx vs. NoFx groups within each race and sex. Race and sex did not modify the relationship between stiffness or FL and fracture status. In the whole cohort, higher stiffness (ORRadius 0.732, [95%CI: 0.563, 0.931], p=0.014; ORTibia 0.866, [95%CI: 0.783, 0.954], p=0.004) and FL (ORRadius 0.597, [95%CI: 0.404, 0.893], p=0.011; ORTibia 0.778, [95%CI: 0.681, 0.888], p<0.001) at the distal radius and tibia were associated with lower odds of incident fracture. Hispanic ethnicity was associated with lower odds of incident fracture independent of radial stiffness (OR 0.289, [95%CI: 0.081, 0.845], p=0.038) and FL (OR 0.286, [95%CI: 0.080, 0.842], p=0.038). In conclusion, in this multiethnic cohort, stiffness and FL were independently associated with prevalent and incident fractures, regardless of race or sex.