Abstract
Background
Thoracic vertebral metastases can compromise spinal stability. Percutaneous vertebroplasty (PVP) and pedicle screw fixation (PSF) are commonly used reconstruction strategies, but comparative biomechanical evidence across different metastatic invasion patterns remains limited.Methods
A CT-based T9-T11 finite element model was reconstructed from a healthy adult volunteer. Four T10 metastatic invasion patterns with increasing vertebral body and posterior element involvement were simulated, and untreated, PVP, PSF, and combined PVP + PSF reconstruction models were generated. The primary analyses used a geometrically linear static formulation under a standardized 1200 N axial compressive load combined with a 7.5 Nm flexion moment. T10 displacement and nodal-averaged maximum von Mises stress were evaluated.Results
Progressive metastatic invasion increased T10 displacement and stress, with extensive bilateral vertebral body and posterior element involvement producing the largest mechanical response. Compared with untreated metastatic models, PVP, PSF, and combined PVP + PSF reduced displacement and/or stress to different extents. PVP showed substantial stress reduction across the simulated groups, whereas PSF primarily improved mechanical stability by limiting displacement, particularly in more extensive invasion patterns. Combined PVP + PSF produced the lowest overall mechanical response in most models, but this finding was interpreted as a biomechanical trend rather than evidence of clinical superiority.Conclusion
Under a standardized geometrically linear loading condition, finite element simulations showed invasion-dependent mechanical deterioration and treatment-specific stabilization trends in a deterministic T9-T11 model. These findings provide exploratory biomechanical evidence for understanding thoracic metastatic instability and reconstruction strategies, but the extreme untreated Group 4 response is an instability indicator rather than a finite-deformation clinical prediction and requires cautious interpretation and further patient-specific validation.