Biomechanical Properties of Osteophytes and Non-Osteophytic Cortical Bone: A Preliminary Study

Introduction: Several studies have associated the development of spinal osteophytes with disc degeneration. Others have characterized them as adaptive bone remodeling in response to unusual stress/strain. No recent study examined the microstructure and mechanical properties of osteophytes. Materials and methods: Bone tissues were harvested from eight different human cadavers. Beams (length: 24mm, width: 4mm, thickness: 2mm) from lumbar osteophytes, lumbar anterior cortices (non-osteophytic), and femoral diaphyseal cortices were tested for three-point bending and micro-hardness. The specimens were subsequently divided into two parts for material density, ash density, and histological analyses. Results: Hardness values (HV) decreased by 39% from femoral cortical to spinal osteophytic samples. The maximum load to failure for osteophytic and non-osteophytic vertebral beams was 64 and 4 Newtons (N), respectively. Material density ranged from 1.40 to 2.0g/cm3 and 1.18 to 1.70g/cm3 for cortical bone and osteophyte, respectively. Undecalcified histology showed a disorganized structure of the osteophytic osteons as compared with the regular pattern observed in femoral diaphyseal cortical bones. Conclusion: Vertebral osteophytes have higher load carrying capacity than vertebral cortical bone. However, cortical bone presents a more mature and organized microstructure than osteophytes.