(Figure 3) Figure 3 Diagram of the points selected for analysis of the shear forces in the three vertebral sections. Tardy’s method of compensation was used to calculate the shear force (��).9 RESULTS Qualitative analysis In the qualitative analysis it was observed that sections B and C had a more homogeneous distribution of shear than in section A. This selleck chemicals Calcitriol section (A) presented low shear concentration in the central region and higher concentrations in the anterior and posterior regions. Section B presented a region of low shear concentration located in the anterior and central region, close to intervertebral disc L4-L5, while section C presented lower shear forces in the anterior, central and posterior region, located close to intervertebral disc L4-L5.

It was also observed that the posterior region of vertebral body L4 has higher shear force, regardless of the section analyzed. (Figure 4). Figure 4 Distribution of shears in sections A, B and C. In section A, the shear concentration was higher in the anterior and posterior regions of the vertebra (arrows). In sections B and C, the shear concentration was higher in the posterior region (arrows). Quantitative analysis In this analysis, the shear forces were calculated at the points corresponding to the three vertebral sections, in all the photoelastic models. The mean values of the shear forces in sections A, B and C are presented in Table 1. Table 1 Values of the means and standard deviation of the shear forces (KPa). In section A, vertebra L4 presented a general average of 21.26 KPa, while section B presented 25.

06 KPa and section C, 35.15 KPa. (Table 1) It can be noted that section C presented a higher general average shear force than section B, which presented a higher general average than section A. The posterior region was the most critical, as it presented higher shear concentrations, mainly in section C. DISCUSSION Due to the mechanical overload to which they are submitted, the vertebrae are susceptible to bone fractures. Most vertebral fractures occur in the thoracic spine,4 yet deformities in the lumbar vertebrae cause greater pain intensity than deformities in the thoracic vertebrae.5 Thus arose the idea of performing photoelastic analysis of vertebral body L4 to understand the transmission of shear forces to the vertebrae.

Photoelasticity is used in the area of Orthopedics and Traumatology, with various articles published, yet no scientific reports using this technique were found in analyses GSK-3 of the influence of the geometry of intervertebral disc L4-L5 on vertebral body L4. The photoelasticy technique used in this trial was able to qualitatively and quantitatively10 evaluate the internal stresses generated by the intervertebral disc geometry. The goal of the quantitative analysis of the fringe orders was to determine the numerical values of the maximum shear forces, especially at the most critical points of the model.