Fig 1. Biomechanical and tomographic methodologies.
Male Wistar rats were subjected to sham operation or orchiectomy. After sacrifice, tibias and femurs from sham and orchiectomized rats were collected for analyses of mechanistic reduced-platen compression (RPC) and four-point bending (FPB) (A and B) as well as micro-computed tomography (μCT) (C). In the RPC test, the upper cortical shell of a tibia was removed in order to expose the trabecular region. The strength of trabecular bone was measured using a circular platen to compress the trabecular bone (A). In the FPB test, a femur was placed across two supporting arms and compressed by double loaded arms with a constant force until the specimen broke (B). The external (α and β) and internal (α' and β') diameters of the femur were measured by μCT in order to calculate the cross-sectional area (CSA) (C). The ultimate stress (σmax) in the RPC and FPB tests were calculated according to two different formulas (D). F maximum, maximum force during loading history; I, area of inertia; Lα, distance between the supporting and loading pins; L loading arm, length of the loading span; L static arm, length of the supporting span.