| Objective To investigate the biomechanical differences in stress and strain between the injured vertebral motion segment model and osteoporotic model after double-segment osteoporotic vertebral compression fracture (OVCF) treated with extension reduction combined with percutaneous kyphoplasty (PKP) using biomechanical finite element method, and to provide biomechanical reference for the prevention and treatment of residual symptoms after surgery in patients with double-segment OVCF. Methods One patient with double-segment OVCF at L1 and L2 and one patient with osteoporosis were selected as research subjects. Three-dimensional finite element mechanical models were established using Mimics, Geomagic, SolidWorks, and ANSYS software. The lower surface of the vertebral body was fixed and supported. A vertical downward force of 500 N was applied to the upper surface to simulate the normal gravity of the human body. Then, torques of 7.5 N·m in positive and negative directions of X, Y, and Z were applied to the upper surface of the model to simulate seven working conditions: axial, flexion, extension, left lateral bending, right lateral bending, left rotation, and right rotation. The stress distribution of cortical bone, cancellous bone, bone cement, and other tissues in each vertebral body was compared and analyzed. Results Biomechanical models of osteoporosis and postoperative OVCF treated with extension reduction combined with PKP were successfully established. Comparative analysis revealed that the overall mechanical behavior of the two-segment compressed fracture model after vertebral augmentation differed from that of the osteoporosis model, particularly in terms of equivalent stress magnitudes and stress concentration trends. Conclusion Combined with previous literature, this study demonstrates that extension reduction combined with PKP improves spinal biomechanical stability in two-segment OVCF patients, but differences remain compared to the osteoporosis model without fractures. These discrepancies may relate to the distribution of bone cement mass within the vertebral body and the material properties of the bone cement, warranting further investigation. |