Quantification of Age-Related Tissue-Level Failure Strains of Rat Femoral Cortical Bones Using an Approach Combining Macrocompressive Test and Microfinite Element Analysis

Abstract

Bone mechanical properties vary with age; meanwhile, a close relationship exists among bone mechanical properties at different levels. Therefore, conducting multilevel analyses for bone structures with different ages are necessary to elucidate the effects of aging on bone mechanical properties at different levels. In this study, an approach that combined microfinite element (micro-FE) analysis and macrocompressive test was established to simulate the failure of male rat femoral cortical bone. Micro-FE analyses were primarily performed for rat cortical bones with different ages to simulate their failure processes under compressive load. Tissue-level failure strains in tension and compression of these cortical bones were then back-calculated by fitting the experimental stress-strain curves. Thus, tissue-level failure strains of rat femoral cortical bones with different ages were quantified. The tissue-level failure strain exhibited a biphasic behavior with age: in the period of skeletal maturity (1-7 months of age), the failure strain gradually increased; when the rat exceeded 7 months of age, the failure strain sharply decreased. In the period of skeletal maturity, both the macro- and tissue-levels mechanical properties showed a large promotion. In the period of skeletal aging (9-15 months of age), the tissue-level mechanical properties sharply deteriorated; however, the macromechanical properties only slightly deteriorated. The age-related changes in tissue-level failure strain were revealed through the analysis of male rat femoral cortical bones with different ages, which provided a theoretical basis to understand the relationship between rat cortical bone mechanical properties at macro- and tissue-levels and decrease of bone strength with age.

Finite Element Investigation of the Effects of the Low-Frequency Vibration Generated by Vehicle Driving on the Human Lumbar Mechanical Properties

“…The effects of muscular constitution were not considered during analysis. Therefore, the conclusions may not be significantly influenced by the exclusion of muscular constitution [ 34 , 35 ]. Several limitations were associated with our modeling method, but the model validation, including static and vibrational loading conditions, illustrated the accuracy of the LFEM.…”

Determination of a tissue-level failure evaluation standard for rat femoral cortical bone utilizing a hybrid computational–experimental method

“…The capability to simultaneously predict the tissue-level yield and failure strains in a single computational simulation may bring an improvement on the investigation of bone mechanical properties and the observation of the changing patterns of bone mechanical parameters among different FE models. 22,33 In general, the precision of FE analysis is mainly dependent on the availability of specimen geometry and material input parameters, as well as the failure mechanism on which they are based. [39][40][41] Here, all FE models were constructed based on the micro-CT images of rat femur.…”

“…Then, the elastic modulus of this element was reduced to 0.5 MPa. 32,33 Apparent yield would be achieved in the FE model as the yielded element reached certain quantities, and the apparent failure phenomenon would be observed with the increase in the number of invalid elements. 6,29 All these simulative procedures were implemented into the ABAQUS/Standard code using the routine UMAT.…”

Animal Models of Osteochondral Defect for Testing Biomaterials

“…e rat models used for OCD regeneration have several advantages, as rats are inexpensive, easy to handle and house, and clinically more relevant than mice. e skeletal maturity of rats is approximately 7 months [34]. Rats aged between 9 and 12 weeks have been used to evaluate the degradation rate and safety profile of biomaterials, whereby the experimental period of implants generally lasts 8-12 weeks ( Table 2).…”