Comparative Evaluation of Biomechanical Testing Methods for Murine Lumbar Vertebral Bodies: Identifying Optimal Techniques for Assessing Bone Structure and Stability

Numerous genetically modified mouse models are available to evaluate gene functions related to bone metabolism regulation. This study aims to evaluate four prevalent biomechanical testing methods for assessing the structure and stability of murine lumbar vertebral bodies, identifying the most reliable, valid, and reproducible technique. The fourth lumbar vertebrae of 20 female C57BL/6 mice (wild type, 12 weeks) were tested, randomized into four testing groups: Method 1 - compression of the complete lumbar vertebral body (LVB) including the dorsal spinal processi; Method 2 - compression at the vertebra body surface; Method 3 - isolated resection of the vertebral arch; Method 4 - resection of the vertebral arch and straightening of the intervertebral joint surface. Compression was applied using a mono-axial static testing machine. Maximum load, stiffness, yield load, and the elasticity modulus were evaluated. Load-to-failure and yield-to-failure were significantly higher in Method 1. Method 3 showed increased stiffness and significantly increased Young's modulus. The least variation in relative load-to-failure and yield-to-failure was observed with Method 1. Method 4 exhibited the greatest overall variation in specimen values. Method 3 yielded divergent results and is not recommended. Method 1 led to the most consistent and reproducible data and is recommended.