Biomechanical behavior of bone tissue in spine instrumentation.

BACKGROUND

The mechanical fixation of the spine in patients with osteoporotic vertebral degeneration is a challenge for surgeons, the vertebrae selected to insert the screws may fail, endangering health and even patient's life.

OBJECTIVE

The objective of the study was to study the effect of the variation of the bone density in the bone-screw interface from a three-dimensional model of the lumbar section.

MATERIALS AND

METHODS

The finite element method was used to model the behavior of the lumbar vertebral section when applying compression loads.

RESULTS

The stresses between 2 and 3 MPa were located on the contact surface with the screw, both in the vertebral body and in the apophysis, being slightly higher in the vertebral body.

CONCLUSIONS

Regardless of bone density, the contact zones between the screws are susceptible to bone tissue failure. The posterior half of the vertebral body was the most sensitive to high values of stress, while in the areas furthest from the axis of the screw stress tended to their minimum.