Numerical Simulation and Evaluation of the Reduced-Platen Compression Test for Estimating Cancellous Bone Mechanical Properties in the Rat

Animal models are utilized in numerous research studies aimed at better understanding skeletal biology, bone biomechanics, and many orthopedic diseases or pathologies. Prominent among these animal models are rodents, most commonly rats and mice. In estimating bone mechanical properties in these animals, cortical bone is routinely assessed by bending one of the long bones such as the femur or tibia, which targets the mid-diaphysis region. Testing specimens of isolated cancellous bone is exceedingly challenging, however, even for the larger rat skeleton. Recognizing the prominence and importance of cancellous bone mechanical properties has led to increased mechanical testing of vertebra and femoral neck specimens in skeletal research employing rats and mice. The specimens in these tests actually consist of a combination of both cortical and cancellous tissue, however. In an attempt to more closely approximate the ideal of isolated cancellous bone specimens a method has been developed recently for testing specimens from the proximal tibia metaphysis and distal femoral metaphysis [1]. In either case, the specimen in this so-called “reduced-platen compression” (RPC) test consists of a section of the metaphysis containing both cortical and cancellous bone. The specimen and test configuration are illustrated schematically in Fig. 1.