COMPARISON OF 3-POINT BENDING TEST AND PERIPHERAL QUANTITATIVE COMPUTED-TOMOGRAPHY ANALYSIS IN THE EVALUATION OF THE STRENGTH OF MOUSE FEMUR AND TIBIA

We compared the mechanical and densitometric testing methods in evalua ting the mechanical strength of mouse cortical hones, The femora and t ibiae of 10 male mice (weight 32.8 +/- 4.0 g) mere utilized, Volumetri c cortical bone mineral density (VCtBMD), cross-sectional cortical are a at midshaft (CSA), cross-sectional moment of inertia (CSMI), and str ength strain index (SSI) mere measured by peripheral quantitative comp uted tomography (pQCT), The precision of pQCT expressed as a coefficie nt of variation (CV) was 1.1%, 2.7%, and 6.4% for vCtBMD, CSA, and CSM I, respectively. The mechanical properties were measured by a three-po int bending test. The method error measured from paired bones mas 7.3% -10.1% for breaking bending force, 15.0%-15.2% for stiffness, 2.0%-2.4 % for vCtBMD, 5.2%-6.4% for CSA, 13.5%-17.6% for CSMI, and 8.9%-18.1% for SSI, CSMI and CSA mere found to be the best explanatory variables for the breaking force of femur and tibial respectively, while CSI-I a nd CSMI were the best predictors for the elastic modulus of femur and tibia, respectively, CSA had a higher correlation with mechanical para meters than VCtBMD. On the basis of this study, the mechanical tests a nd the pQCT measurements are relevant in biomechanical studies on mous e bones and justify the use of the murine model, High-resolution pQCT gives better precision than the three-point bending test in studies of mouse bones. (Bone 23:155-161; 1998) (C) 1998 by Elsevier Science Int . All rights reserved.