Deformational and strength properties of full-scale models of transpedicular fixation and supportive spinal fusion in thoracic and lumbar regions

Objective: the evaluation of stability for various options of thoracic and lumbar spine fixation in static load. Material and methods. We used the anatomical preparations of the thoracic and lumbar porcine spines to model comminuted vertebra fractures A4 (AOSpine, 2013) in the middle of the anatomical block. The models were later used to install 4 most common types of metal fixation, and to study their deformation-strength properties in controlled axial compression, including maximum load and stress. Results. The increasing differences in the median values of maximum loads (H)and stresses (MPa) were found at controlled axial compression in models of 4-screw(2980 H, 7.18 MPa) and 8-screw (4240 H, 9.78 MPa) transpedicular fixation, 4-screw (6460H, 15.27 MPa) and 8-screw (10120 H, 103.21 MPa) transpedicular fixation and supporting spinal fusion, leading to axial deformation and/or destruction of metal structures, as well as destruction of the vertebrae bone structures. Conclusion. The model of 8-screw transpedicular fixation and supporting spinal fusion has the greatest stability in controlled axial compression; all its nodes in the metal structure remain stable and the bone structures of the vertebrae are preserved.