Effect of a novel compressible artificial disk on biomechanical performance of cervical spine: A finite element study

Abstract

Spinal interbody fusion is the most common surgery for treatment of disk degeneration, but the increased stress on adjacent level has been noted. Disk replacement has become an alternative strategy for dealing with problem of disk degeneration. Compressibility of an intact intervertebral disk is contributive to protect spinal structure, but certain mechanism has seldom been preserved in most of the commercial products of ball-and-socket-styled artificial disks. A novel compressible artificial disk design for cervical spine has been developed and compared the biomechanical behaviors with intact and incompressible models by finite element method. Physiological loadings have been applied for evaluating the biomechanical performances in different implant designs. Compressible mechanism represented a similar kinematic behavior to intact cervical spine model. Greater mobility and larger facet joint contact force were observed in incompressible disk model. Biomechanical performances of cervical artificial disk with compressible mechanism may be better reproduced to those of intact cervical spine under physiological loadings. With adequate assigned structural stiffness of the compressible mechanism in the artificial disk, the concept is worth considering for further cervical artificial disk designs.

Optimization of Three-Level Cervical Hybrid Surgery to Prevent Adjacent Segment Disease: A Finite Element Study

“…The maximal IVD stress of the present model was 3.7 Mpa to 3.7 MPa (Figure 3). (Goel and Clausen, 1998;Chen et al, 2015). The ratio of the facet contact force to the applied axial loading was also calculated and the result was presented in Table 4.…”

Biomechanical evaluation of a dynamic fusion cage design for cervical spine: A finite element study

“…Table 1 represents the applied mechanical properties of the finite element models according to the previous literatures. 9,10 The coefficients of friction at contact pairs are assigned by 0.5 at bone-cage interface, 0.1 between facet joints 11 and frictionless while the self-engagement of the Z-Brace Dynamic Fusion Cage occurs. Physiological environment of cervical spine models was applied by exerting an axial load of 73.6 N at the top of C3 superior endplate, while the bottom of C5 inferior endplate was fixed.…”

“…A validated cervical spine (C3-5) finite element model 9 has been used in this study (INT model). The two cage models were virtually inserted into the C4-5 intervertebral space at centre-centre location after the removal of intervertebral disc structure (Figure 3).…”

“…Physiological environment of cervical spine models was applied by exerting an axial load of 73.6 N at the top of C3 superior endplate, while the bottom of C5 inferior endplate was fixed. 9,10 Functional activities of cervical spine that 12°of flexion, 7°of extension, 8°of lateral bending and 4°of axial rotation were simulated for all models. The motion was defined by the final position and angular movement of C3 vertebral body, with a general concept of displacement control method for spinal movement simulation.…”