Effects of New Cage Profiles on the Improvement in Biomechanical Performance of Multilevel Anterior Cervical Corpectomy and Fusion: A Finite Element Analysis

Abstract

For multilevel cervical fusion, anterior corpectomy and fusion (ACCF) induces more implant-related complications than anterior diskectomy and fusion (ACDF), which implies that the biomechanical stability of ACCF may be insufficient. The aim of this study was to assess whether the optimization of the cage profiles could improve the biomechanical performance of multilevel ACCF. Three finite element models were constructed and compared, including 3-level ACDF, 2-level ACCF using a conventional cage for reconstruction, and 2-level ACCF using a new cage for reconstruction. The ends of the new cage possessed additional end rings and emulated the end plate geometries. The ranges of motion (ROMs) of the surgical segments and the stress peaks in the end plate, fixation system, and screw-bone interface were compared. Compared with preoperative status, ACDF and ACCF reduced the segmental ROMs by 96.1%-98.2%. The end plate stress peaks were the highest in ACCF using the conventional cage (10.1-18.6 MPa), followed by ACCF using the new cage (7.7-14.3 MPa) and ACDF (5.3-9.1 MPa). ACDF induced the highest stress peaks in the fixation system and screw-bone interface (32.5-39.3 MPa and 12.1-12.7 MPa, respectively), followed by ACCF using the conventional cage (20.4-31.7 MPa and 10.3-13.6 MPa, respectively) and ACCF using the new cage (18.6-25.7 MPa and 9.7-12.6 MPa, respectively). The application of the new cage decreased the risks of cage subsidence and instrument-related complications in multilevel ACCF. Under the condition where cage subsidence was prevented, ACCF was superior to ACDF in terms of construct stability and avoiding instrument-related complications.