Three-point bending test of the femur

One femur from each specimen was subjected to a three-point bending test until failure to assess fracture resistance. Prior to loading, the length of each femur was measure to the nearest hundredth of a millimeter using digital calipers and the location of the midshaft was marked in pencil. Force was applied to the midshaft in the anterior-posterior direction at 0.5 N/s using a tip with a rounded edge (HP-5 with HSV Test Stand; Handpi Instruments Co., Ltd, China). Femurs were held on two supports that were positioned to contact the proximal and distal ends of the bone. The distance between supports was not held constant because femur length varied greatly in our sample and measurements of material properties of bone are proportional to the distance between the supports and the diameter of the bone in the breaking plane [29, 30]. Data on ultimate force, maximum displacement until failure, and time to failure were recorded. The location of the fracture expressed as a percentage of the total femur length along the long axis was also measured.