Biomechanical Study between the Rigid and Dynamic Fixation Systems of the Spinal Column Analyzed by the Finite Element Method

Abstract

Orthopedic fixation devices are widely used in treatment of spinal diseases. It is expected that application of dynamic stabilization confers valuable movement possibility besides its main role of load bearing. Comparative investigation between pedicle screw model rigid fixation and (B Dyne, Elaspine, Bioflex, Coflex rivet) models dynamic fixation systems may elucidate the efficacy of each design. The goal of the present study is to evaluate the efficacy of five fixation systems mounted on L4-L5 motion segment. In this numerical study, a 3D precious model of L4, L5 and their intervertebral disc has been employed based on CT images. Five fixation devices have been also implanted internally to the motion segment. Finite element method was used to evaluate stress distribution in the disc and determine the overall displacement of the segment as a measure of movement possibility. The results show that the Coflex rivet implantation can provide stability in all motions and reduce disc annulus stress at the surgical segment L4-L5. On the other hand, maximum stress in the disc has been observed in dynamic systems but within the safe range. The greater movement of the motion segment has also appeared in dynamic fixations. Existence of the fixation systems reduced the stress on the intervertebral disc which might be exerted in intact cases. Use of the fixation devices can considerably reduce the load on the discs and prepare conditions for healing of the injured ones. Furthermore, dynamic modes of fixation confer possibility of movement to the motion segments in order to facilitate the spinal activities.

Static study and numerical simulation of the influence of cement distribution in the upper and lower adjacent vertebrae on sandwich vertebrae in osteoporotic patients: Finite element analysis

“…von Mises stress (VMS) and maximum displacement values were analyzed for T12 vertebrae, T11/T12 and T12/L1 discs. Material properties were defined for each construct (Table 1) and elemental information is shown in Table 2 26,33–39 …”

“…Material properties were defined for each construct (Table 1 ) and elemental information is shown in Table 2 . 26 , 33 , 34 , 35 , 36 , 37 , 38 , 39 …”

Three-Dimensional Biomechanical Finite Element Analysis of Lumbar Disc Herniation in Middle Aged and Elderly

“…About 80% of people have experienced some degree of lumbar and leg pain [ 3 , 4 ]. In quite a number of patients, conservative treatment with physical therapy can relieve pain, and since the disc receives the least pressure during bed rest, it is recommended to rest for up to 1 week and then gradually return to normal activity [ 5 ]. Surgery is recommended for patients with no relief of pain after at least 6 weeks of conservative treatment.…”

Optimization of the Material of External Fixator with FEM Simulation

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Patients and surgeons with tibia fracture using external fixator are worried about a higher weight of metal fixator´s construction and therefore also poor manipulation ability with this tool [1]. During the last few years the bone tissue engineering has improved significantly and along with that also material development has increased [2,3]. Therefore patients requirements can be achieved by optimizing the material composition of this product.

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