Relationship Between the Elastic Modulus of the Novel Pedicle Screw-Plate System and Biomechanical Properties Under Osteoporotic Condition: A Power-Law Regression Analysis Based on Parametric Finite Element Simulations.

BACKGROUND AND

OBJECTIVE

The novel pedicle screw-plate system (NPSPS) is a new internal fixation method for the thoracic spine that we proposed, which has demonstrated effectiveness through clinical practice and biomechanical testing. Nevertheless, the optimal elastic modulus of NPSPS (NPSPS-E) remains debated, particularly for osteoporosis patients. We propose a more efficient method to predict the biomechanical effects of NPSPS across varying elastic moduli in osteoporosis using parametric finite element (FE) analysis, establishing the regression relationship between NPSPS-E and biomechanical properties.

METHODS

An FE surgical model of NPSPS under osteoporotic conditions was developed. The NPSPS-E was linearly varied from 3.6 GPa (polyether ether ketone) to 110 GPa (titanium alloy). Using power-law regression analysis, a functional equation was established to correlate NPSPS-E with biomechanical properties under osteoporotic condition.

RESULTS

Power-law equations and regression models were successfully established between NPSPS-E and biomechanical prediction indices under osteoporotic condition (P<0.0001). As NPSPS-E increased, the range of motion (ROM) of the T8-T10 spinal segments decreased from 0.51°-4.06° to 0.24°-1.45°. The mean von Mises stress in the T8-T10 vertebrae declined from 1.36 MPa-2.03 MPa to 1.15 MPa-1.79 MPa. Concurrently, the stress shielding ratios and the total stress ratios of the NPSPS increased from 3.66%-48.07% and 13.96%-26.96% to 10.70%-56.20% and 52.62%-64.40%, respectively.

CONCLUSION

The functional equations derived from these models serve as a predictive tool to directly estimate the biomechanical effects of NPSPS across a range of elastic modulus under osteoporotic conditions, thereby facilitating the design and optimization of NPSPS materials.