Biomechanical analysis of vertebral wedge deformity in elderly women with quantitative CT-based finite element analysis

Background To explore the vertebral deformity angle (VD angle) of 1(st) lumbar vertebral body (L1) in elderly women, investigate the influence of VD on vertebral stiffness (VS) by biomechanical analysis using quantitative computed tomography-based finite element analysis (QCT-FEA). Methods Two hundred seventy eight participants were recruited, and underwent QCT scan. Measured VD angles of L1, and constructed QCT-FEA models of L1 with the minimum (0.59 degrees), median (5.79 degrees) and maximum (11.15 degrees) VD angles, respectively. Loads in two directions were applied on the upper edge of L1 with a force of 700 N, and vertebral stiffness (VS) was defined as the ratio of 700 N and displacement at the superior reference point: (1) perpendicular to the upper edge of L1 (defined as VS-U); (2) perpendicular to the lower edge of L1(defined as VS-L). Results Age was very weak positively correlated with VD angle, moderate negatively correlated with vBMD, and moderate negatively correlated with VS (P < 0.05). VS-U was significantly different among three VD angles, so was VS-L (P < 0.001). VS-U was higher than VS-L in 5.79 degrees and 11.15 degrees VD angles (P < 0.05), however no difference in 0.59 degrees VD angles (P > 0.10). Conclusions VD angle of L1 was slightly increased with age and not correlated with vBMD, and VS was moderate negatively correlated with age, showing that the vertebral body was more likely to fracture with aging. VS-U and VS-L were gradually decreased with the increase of VD angle, and VS-L was lower than VS-U with the increase of VD angle, which showed that vertebral body was more prone to fracture when the load was perpendicular to the lower edge of the vertebral body as the VD angle increasing.

Automated summary

The study explored the VD angle of L1 in elderly women and its impact on vertebral stiffness using QCT-FEA. Results showed a slight increase in VD angle with age, moderate negative correlation between age and VS, and no correlation between VD angle and vBMD. Vertebral stiffness gradually decreased with higher VD angle, and fracture risk increased when load was perpendicular to the lower edge of the vertebral body.