Bilateral symmetry of biomechanical properties in rat femora

Abstract

In many studies, bone healing and remodeling have been examined in various animal models using one femur as a control for the contralateral femur based on the assumption that they are bilaterally symmetrical. Symmetry studies have been limited mainly to geometrical properties. The purpose of this study was to determine whether or not there is symmetry in the mechanical properties of rat femora. Two strain gauges were attached to the anterior surface parallel to the long axis of explanted femora of retired female breeder and 120-day-old male Sprague Dawley rats. Femora were mechanically tested in cantilever bending and the strain values were recorded. Moments of inertia, cortical areas, and moduli of elasticity were determined from strains and cross-sectional properties. Female femora showed a bilateral strain difference of less than 2.2% and an elastic modulus difference of less than 8.7%. Males had less than 2.0% and 7.9% differences for strain and elastic moduli, respectively. Statistical analysis showed no significant difference between left and right femoral strain values for the females, but modulus differences were significant different at the p = 0.05 level. There was no significant difference in strain and modulus values for the males, indicating mechanical and geometrical symmetry of their femora.

Bilateral symmetry of biomechanical properties in mouse femora

“…In this case, it is important to characterize the degree of variability present within animals and between animals to assess whether changes noted between animals are significant. For these reasons, many studies have compared the geometrical properties of paired bones in animal models and some studies have measured the bilateral symmetry in paired bones of animal models [6][7][8].…”

“…This difference is likely a result of testing methodology. Since the bone modulus in small animals is expected to be similar and the elastic moduli determined for rat femora in cantilever bend testing [8] has been noted to be similar to the moduli measured in this experiment, three point bending and cantilever loading are likely creating different strain patterns in the bone. This argument is supported by published evidence which shows that the elastic moduli reported for rat femora measured using three point bending were significantly lower than moduli measured in cantilever bending [8,13].…”

Effect of treatment with simvastatin on bone microarchitecture of the femoral head in an osteoporosis animal model

“…Femurs were collected at each sacrifice time. According to Battraw et al (), the pair of femurs and tibias has similar geometry and mechanical behavior when compared to their sides (left and right). Thus, the left side was used for histological analysis and the right side used for mechanical tests.…”

Long-term measurement of bone strainin vivo: The rat tibia

“…At week 10, animals were euthanized, the tibiae harvested, and the integrity of the bond between bone and gauge determined ex vivo as previously described. 25 Briefly, the strain response of the test gauge to a fixed load was compared to the response of a gauge freshly glued to the contra-lateral tibia. Measurements from animals with strains above 80% of glued controls were considered to be functional and were reported.…”