Bone mass, bone architecture and bone material properties are the principal determinants of bone strength. In this study we tester whether bone material properties can be considered an independent risk factor of osteoporotic fracture and also whether it predicts fracture severity. We performed microindentation at the anterior tibia, using (Osteo Probe III) in 41 controls and 61 patients with postmenopausal osteoporosis, (20 cases with hip fracture, 30 cases with vertebral fracture and 11 patients with non-vertebral non-hip fracture). The indentation distance increase was standardised into a calibration phantom (poly methyl-methacrylate) and converted to (Bone Material Strength (BMS) units). Bone mineral density (BMD) was measured by dual X-ray absorptiometry. Vertebral fracture severity was determined by semi-quantitative (Q7) grading of compression fractures on lateral X-rays of the DXA-scanner. BMS was found to be significant lower in subjects with osteoporotic fractures than in controls (77±7.1vs 71.2±6.5, p<0.05). A significant negative correlation was observed for BMS on fracture Q7 severity (r2=0.234, p=0.012). After adjusting for age and lumbar spine BMD, (r2=0.153, p=0.012). For BMS, each incremental decrease of one unit in BMS was associated with a 9% increase in the likelihood of exhibiting fracture (OR 0.91, 95% CI 0.85, 0.97 p=0.005). In the fracture group, BMD was lower at the total hip (0.784±0.10 vs 1.161±0.10 in controls; p<0.05) and spine (0.855±0.194 vs 1.185±0.178; p=0,025). Serum markers of bone turnover (CTX and P1NP) were elevated in the fracture group vs. controls (p=0.035 and p=0,016), respectively. Regression analysis revealed that BMS-values did no vary with BMD, age, or markers of bone turnover. In conclusion, bone material properties constitute an independent risk factor for osteoporotic fractures and severity of vertebral fractures.
Disclosure: The authors declared no competing interests.