A novel anterior occipitocervical fixation instrument improves stability and minimizes bone-implant stress: a comparative finite element analysis

Purpose Posterior fixation is commonly the preferred surgical method for occipitocervical instability. In certain cases, posterior surgery no longer holds an advantage, and it is more advisable to choose the anterior approach. Furthermore, some internal fixation failures are stress-related. Therefore, we designed three types of anterior fixation instruments and evaluated them via finite element analysis, aiming to identify a design that enhances stability while minimizing stress at the bone-implant interface.Methods We performed a finite element analysis using a validated C0-C2 model with simulated instability. Three distinct instruments were virtually implanted: Occipital Condylar Plate (OCP); Atlanto-Occipital Transarticular Plate (AOP); and Atlantoaxial-Occipital Plate (AAOP). We applied a 40-N axial load and 1.5-Nm moments to simulate flexion, extension, lateral bending, and axial rotation. Segmental range of motion (ROM) and von Mises stress at the implant and bone were analyzed.Results All three instruments increased stability. However, the OCP design was markedly superior, reducing flexion ROM by 50-61.54% compared to the AOP and AAOP, respectively. Most critically, the OCP demonstrated the lowest von Mises stress at the bone across all motion states. Its stress distribution was also the most uniform, in stark contrast to the high stress concentrations observed with the other designs.Conclusions Among the three instruments, the OCP provides the most robust stability and, crucially, the most favorable stress environment, which may reduce the clinical risk of stress-related internal fixation failure.