Prediction of the Cervical Spine Instability under Facet Joint Resection Extent of Foraminotomy by Using Finite Element Analysis

This study aimed to quantify the biomechanical effects of varying extents of facet joint resection during cervical foraminotomy using finite element analysis (FEA), and to compare outcomes under open versus minimally invasive surgical conditions. A validated cervical spine model (C3–C6) was used to simulate unilateral foraminotomy at C4–C5 with progressive left facet joint resection from 0% to 100% in 12.5% increments. Biomechanical parameters, including range of motion (ROM), intradiscal pressure (IDP), and annular peak von Mises stress (PVMS), were analyzed to evaluate spinal stability and degeneration risk. Resection beyond 62.5% resulted in marked increases in ROM (2–18% in left lateral bending, 6–26% in right axial rotation). IDP rose by up to 23% in left lateral bending and 38% in right axial rotation at ≥ 87.5% resection, while PVMS increased sharply in right axial rotation and moderately in extension beyond 50%. These findings identify 62.5% as a critical instability threshold. While our current analysis focused on osseoligamentous structures, future work will incorporate the effects of paraspinal musculature to better reflect minimally invasive surgical conditions. Our results provide quantitative evidence to guide surgical decision-making in balancing adequate decompression with the preservation of cervical stability.