A finite element-based comparative dynamic biomechanical study of a novel oblique lateral locking plate system (OLLPS) versus traditional internal fixations for oblique lumbar interbody fusion (OLIF) under whole-body vibration

Objective: To evaluate the biomechanical performance of the novel OLLPS in OLIF surgery, including its dynamic stability and application safety, thereby providing evidence-based support for optimizing OLIF combined internal fixation strategies. Methods: Five surgical finite element analysis models with OLLPS or traditional internal fixation were established based on a validated L1-S1 intact model. A 400N follower load was applied along the lumbar curvature to simulate partial body weight; simultaneously, a 5Hz, ±40N sinusoidal vertical load was added to L1 vertebral upper surface to simulate whole-body vibration (WBV) during driving on regular paved roads, with a loading duration of 2 s. Post-loading, peak dynamic response parameters of surgical and adjacent segment structures were extracted, and their maximum and minimum values and vibration amplitudes were recorded. Results: Bilateral pedicle screw fixation (BPS) provides the greatest reduction in surgical segment endplate stress (59.41%-60.35% reduction in L5 superior endplate) and cage stress (a maximum reduction of 68.19%), but induces the highest increases in adjacent segment (especially L5/S1) intervertebral disc stress (IDS) and facet joint stress (FJS). OLLPS effectively reduces surgical segment stress; despite its relatively high implant stress, it caused less adjacent segment interference than BPS. 2-screw and 4-screw lateral plate fixations had weaker stress-modulating effects than BPS and OLLPS. Additionally, the IDS and FJS at L3/4 generally exceeded those at L5/S1, and the IDS and FJS at L5/S1 were more strongly influenced by the fixation scheme. Conclusion: In OLIF, different supplemental fixations induce differing dynamic biomechanical responses at surgical and adjacent levels. Compared with traditional internal fixations, OLLPS based on locking structure and reverse pedicle screw trajectory design provides balanced biomechanical compatibility in stability and adjacent-segment disturbance. The fixation scheme with appropriate stiffness should be prioritized based on patients' adjacent-segment degeneration status to reduce the related risks.