Reducing Variability In Murine Long Bone Mechanical Testing: A Contactless Bending Approach For Improved Reproducibility

Abstract

Bone, a vital structural component of the musculoskeletal system, deteriorates due to age, sex, and various pathological conditions. Common techniques for evaluating whole-bone strength and fracture susceptibility include 3-point and 4-point bending tests in murine models, which replicate physiological loading conditions. Despite the widespread use of these methods, significant variability exists in reported mechanical indices, highlighting the need for a standardized approach to ensure reliable and comparable data. Finite element analysis (FEA) simulations were performed on a mouse femur to identify potential sources of heterogeneity within the point-bending set up. A novel contactless bending mechanical testing system and protocol was also developed to eliminate the variabilities associated with traditional bending tests. FEA simulations demonstrated that angular malalignment of the bone in the test frame could result in up to 72% differences in modulus values. The contactless bending system, validated through digital image correlation (DIC), showed comparable mechanical properties to existing literature, with reduced coefficient of variance in mechanical indices. The contactless bending system offers improved precision and reproducibility over the point-bend method to enhance the reliability of bone mechanical testing in skeletal research. Future work should focus on further validation and refinement of this novel approach.