FEMORAL-NECK STRENGTH OF MOUSE IN 2 LOADING CONFIGURATIONS - METHOD EVALUATION AND FRACTURE CHARACTERISTICS

We evaluated the mechanical strength of murine femoral neck in two loa ding configurations. The mechanical strength of the left femora of 25 male mice (weight 39 +/- 4 g) were measured in an axial configuration simulating one-legged stance in a human, and the right femora were tes ted in a configuration simulating a fall to the lateral side, on the t rochanter. The reproducibility of the mechanical testing was 1.6% in t he axial configuration and 3.7% in the fall configuration. The femoral neck was slightly stronger in the fall configuration. Typically, a lo ad in the fall direction associated with a basicervical fracture, whil e axial loading resulted in both mid- and basicervical fractures. The linear bivariate correlation coefficient between the mechanical streng ths in the two loading configurations was 0.83. Total bone mineral con tent (BMC), cortical bone mineral content (CtBMC), volumetric cortical bone mineral density (vCtBMD), and cross-sectional cortical area (CSA ), measured at the femoral neck by peripheral quantitative computed to mography (pQCT), had a significant relationship with the femoral neck strength in the axial configuration. The coefficient of variation of t he pQCT measurements was 9.1, 5.5, 2.3 and 5.5% for BMC, CtBMC, vCtBMD and CSA, respectively. We conclude that the precision of pQCT is mode rate in evaluating the femoral neck of the mouse, and vCtBMD is the mo st reproducible parameter. The mechanical strength of the murine femor al neck can be measured with high precision by the two mechanical test ing configurations presented here. (C) 1998 Elsevier Science Ltd. All rights reserved.