Three-dimensional finite element analysis of a novel interzygapophyseal fusion device for lower cervical spine.

ABSTRACT

PURPOSE: A three-dimensional finite element model of the lower cervical spine was established to evaluate the biomechanical stability and stress distribution of the new lower cervical interzygapophyseal fusion device (IZFD) developed by ourselves under different construct. The aim of this study was to provide theoretical basis for further clinical application. METHODS: A normal fresh cadaveric specimen (male, 35 years old) was used to establish an intact three-dimensional finite element model of C3-C6. On this basis, the comparative finite element models of the lateral mass screw rod (LMSR) system and LMSR+IZFD were established. Only C4-C5 is fixed in the lateral mass. The range of motion (ROM) and stress distribution in the flexion,extension, lateral bending and rotation of the C4-C5 segment under the three constructs were analyzed. RESULTS: The ROM and stress distribution of the three-dimensional finite element model under load construct were within a reasonable range, which proved the validity and reliability of the model. The ROM and stress distribution of C4-C5 segment was significantly decreased in both LMSR and LMSR+IZFD constructs than those in the intact construct. The ROM and stresss distribution were even smaller in LMSR+IZFD construct than in LMSR construct. CONCLUSIONS: The IZFD combined with LMSR system can provide satisfactory stability for the lower cervical spine, and the IZFD can further improve the fixation effect of the LMSR system.