[Biomechanics of the bone-screw interface in transpedicular spinal instrumentation].

Implant loosening, catastrophic failure of the bone-screw interface, material migration, and loss of stability of the fixation component assembly constitute a serious complication in adult spinal surgery. The contribution of biomechanics is based on experimental measurement and simulation of transpedicular spinal fixations. The cortical insertion trajectory showed an increase in the resistance of the screw-bone interface with respect to the pedicle insertion trajectory, both for axial traction forces to the screw and for stress distribution in the vertebra.

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.

3D patient-specific model of the tibia from CT for orthopedic use.

Objectives: 3D patient-specific model of the tibia is used to determine the torque needed to initialize the tibial torsion correction.

Methods: The finite elements method is used in the biomechanical modeling of tibia. The geometric model of the tibia is obtained from CT images.