Biomechanical Evaluation of Compressive Stress in Lumbar Vertebrae – A Pilot Survey

Abstract

Background: Cadaveric research in orthopedics poses challenges for medical students and early-career professionals due to limited resources, mentorship, and technical support. High costs and study complexity further deter clinically impactful projects. This study was done to evaluate the clinical significance of a simplified biomechanical model of compressive stress to failure across lumbar vertebrae (L1–L4). We hypothesize that this model accurately represents the increased strength of the lower lumbar vertebrae, correlating with the greater loads they support in vivo. Methodology: Fourteen lumbar vertebrae (L1–L4) from four cadavers (aged 66–95 years) were tested for compressive stress to failure using an Instron model 5982. Vertebrae were harvested, cleaned, and subjected to compressive loading to generate stress–strain curves and calculate Young’s modulus. Our findings were compared with the current cadaveric research models. Results: Young’s modulus of lumbar vertebrae studied ranged from 1.81 MPa to 8.54 MPa, with no consistent trend of increased stress tolerance in lower levels. One-way ANOVA showed no significant differences between lumbar levels (P = 0.64). Incorporating data from four cadaveric studies, we found that the degeneration of vertebrae had greatest impact on L4 and contributes to most vulnerability in mechanical properties and stress-strain behavior. Conclusion: Our findings show no significant differences in compressive stress tolerance across lumbar levels in the elderly, with the greatest impact at L4. The observed variability underscores the need for further research on multidirectional loading and degenerative effects to refine clinical strategies.

Keywords

• biomechanical analysis
• lumbar biomechanics
• orthopedics
• young’s modulus