Finite Element Analysis of the Biomechanical Effect of Coflex™ on the Lumbar Spine

Abstract

ObjectiveThe biomechanical properties of the Coflex™ (Paradigm Spine, NY, USA), a device designed to provide dynamic stabilization without lumbar fusion, have not been clearly defined. The purpose of this study was to determine the efficacy and biomechanical effect of Coflex™ using finite element model (FEM).MethodsA 3D geometric model of the L3-L5 was created by integrating computerized tomography (CT) images. Based on the geometric model, a 3D FEM was created and the Coflex™ model was incorporated into the base model. Mechanical load dependent on the postural changes and boundary conditions, were imposed to simulate various 3D physiological states. The simulation analysis included stress and strain distributions, intervertebral disc deformation, and the range of motion of the facet joint and lumbar spinous process.ResultsCoflex™ significantly restrained displacement in extension, lateral bending and compression of joint between the L4-5 as one in the experimental group was observed -1.3% of flexion, -24.5% of extension, -44.5% of lateral bending and -37.2%. The average intradiscal pressure of the L4-5 decreased by 63% and the average facet contract force of the L4-5 decreased markedly by 34% in the experimental group. A load of 120 MPa from extension was observed at the base of spinous process in the experimental group.ConclusionThe Coflex™ can be safely used for achieving functional dynamic stabilization of the lumbar vertebral column while preserving the intactness of the other components. However, the fatigue fracture of the L4 spinous process should be carefully monitored.

The effect of the backpack on spine.

“…Fig (20) shows that the mixed loading (P1 compression + bending moment (P3)) has a contour of maximum stresses red part in the disc D1 and we see in this figure the front part of the disc D1 is pulled and another compressed part, other hand \ " (Fig. 20) \" clearly shows that the backpack is a repeated effort to back into everyday life ultimately cause disc problems, particularly at the lumbar region (lumbar disc herniation).…”

Biomechanical changes of degenerated adjacent segment and intact lumbar spine after lumbosacral topping-off surgery: a three-dimensional finite element analysis

“…The non-fusion surgery can minimize the influence on adjacent segments by preserving the motion of the lesion segments to prevent the occurrence of ASDeg. However, when faced with severe clinical situation of lumbar instability, osteoporosis and severe spinal stenosis, fusion is usually needed [5,6,13,18]. The increase of movement and stress of adjacent segments after fusion is the main cause of ASDeg, moreover, for the degenerated adjacent disc, fusion may accelerate degeneration process, even result in symptomatic degeneration [19,20], especially for those with indications of fusion and moderate degeneration in the superior adjacent disc(Pfirrmann grade II-IV) [21], the fusion segments should be minimized while achieving good clinical results.…”

“…Meanwhile, the posterior facet space was set to 0.5 mm. Finally, the model was simulated according to the parameters reported in the current literature, and the specific data is shown in Table 1 [8,9,[11][12][13].…”

Finite element analysis of a ball‐and‐socket artificial disc design to suppress excessive loading on facet joints: A comparative study with ProDisc

“…To validate the intact FE model, we applied the same loading and boundary conditions used by Yamamoto et al in a representative in‐vitro study for validating the FE model , . The boundary and loading conditions and the validation results have been described in detail previously .…”

“…To validate the intact FE model, we applied the same loading and boundary conditions used by Yamamoto et al in a representative in-vitro study for validating the FE model. 15,16,[21][22][23] The boundary and loading conditions and the validation results have been described in detail previously. 15,16 To analyze the biomechanical effects, the follower load that 24 The load amount and path were adopted from previous studies.…”