Bench tests for characterizing the mechanical performance of spinal fusion cages can produce inconsistent results. While intra-lab experiments are very repeatable, inter-lab results often display high levels of variability. Differences in test protocols, load fixtures, and interpretation of experimental data can all influence results. This makes it difficult to evaluate the relative performance of spinal fusion cages. Finite element analysis (FEA) may provide a more repeatable alternative to bench testing. However, there are currently no standards or best practices for characterizing the mechanical behavior of spinal fusion cages with FEA. As such, the quality of FEA practices used to characterize the mechanical performance of spinal fusion cages varies widely. An investigation of spinal fusion cage 510(k) submissions from 2013 to 2017 revealed that most finite element models lack the items needed to establish credibility. Moreover, a survey of industry stakeholders indicated that while most companies conduct FEA, most of the modelers do not consult any best practices documents. This lack of repeatability and guidance creates additional burden for industry modelers and government reviewers. Industry stakeholders and government regulators need a consistent method for implementing FEA in the determination of spinal fusion cage mechanical performance.
The title and scope are in draft form and are under development within this ASTM Committee.