Population-based design and 3D finite element analysis of transforaminal thoracic interbody fusion cages

OBJECTIVE: To compare the biomechanical characteristics of two transforaminal thoracic interbody fusion cages based on the Chinese population thoracic anatomy. METHOD: Computed tomography scans of the thoracic spine of 150 patients from our institution were collected and analysed. Two cages were designed based on the anatomical parameters of these patients. Further, we used 3D finite element analysis models to compare the stability of two cages by using Mimics 17.0 and ANSYS 15.0 software. RESULT: Two kinds of thoracic cages (box and kidney-shaped) were designed. Under the displacement working condition, the two new fusion cages could achieve immediate postoperative stability, but the kidney-shaped cage was better than the box-shaped cage. Under the stress working condition, no highly focused stress area was found in either cages, but the kidney-shaped cage experienced less stress than the box-shaped cage. CONCLUSION: The kidney-shaped cage is more stable and experiences lesser stress than the box-shaped cage after thoracic intervertebral fusion, and it is more suitable for Chinese transforaminal thoracic interbody fusion. THE TRANSLATIONAL POTENTIAL OF THIS ARTICLE: This article is about thoracic fusion cage design and finite element analysis (FEA) analysis based on the thoracic anatomy parameters. For there is currently no suitable thoracic fusion cage for transforaminal thoracic interbody fusion, the results in this article may have the potential of transferring the two designed cages into clinical use.