Reference values and clinical predictors of bone strength for HR-pQCT-based distal radius and tibia strength assessments in women and men.

Reference values for radius and tibia strength using multiple-stack high-resolution peripheral quantitative computed tomography (HR-pQCT) with homogenized finite element analysis are presented in order to derive critical values improving risk prediction models of osteoporosis. Gender and femoral neck areal bone mineral density (aBMD) were independent predictors of bone strength. INTRODUCTION The purpose was to obtain reference values for radius and tibia bone strength computed by using the homogenized finite element analysis (hFE) using multiple stacks with a HR-pQCT. METHODS Male and female healthy participants aged 20-39 years were recruited at the University Hospital of Bern. They underwent interview and clinical examination including hand grip, gait speed and DXA of the hip. The nondominant forearm and tibia were scanned with a double and a triple-stack protocol, respectively, using HR-pQCT (XCT II, SCANCO Medical AG). Bone strength was estimated by using the hFE analysis, and reference values were calculated using quantile regression. Multivariable analyses were performed to identify clinical predictors of bone strength. RESULTS Overall, 46 women and 41 men were recruited with mean ages of 25.1 (sd 5.0) and 26.2 (sd 5.2) years. Sex-specific reference values for bone strength were established. Men had significantly higher strength for radius (mean (sd) 6640 (1800) N vs. 4110 (1200) N; p < 0.001) and tibia (18,200 (4220) N vs. 11,970 (3150) N; p < 0.001) than women. In the two multivariable regression models with and without total hip aBMD, the addition of neck hip aBMD significantly improved the model (p < 0.001). No clinical predictors of bone strength other than gender and aBMD were identified. CONCLUSION Reference values for radius and tibia strength using multiple HR-pQCT stacks with hFE analysis are presented and provide the basis to help refining accurate risk prediction models. Femoral neck aBMD and gender were significant predictors of bone strength.