Numerical analysis of multi-level versus short instrumentation for the treatment of thoracolumbar fractures.
OBJECTIVE
The research analyses the strength of metallic implants in posterior spinal instrumentation for the treatment of thoracolumbar fractures, considering extended and short fixation techniques on the immediate post-surgical load. Considering that short fixation may bring the advantage of a less invasive surgical procedure to the patient and may also result in lower costs, this evaluation becomes necessary.


METHODS
Three-dimensional modelling of the thoracolumbar spine was initially performed. CT images were captured and converted for analysis with the ANSYS program. Both treatment techniques were analysed for stresses, and strains generated in the immediate postoperative period, when the fracture is still not healed.


RESULTS
The maximum stress obtained for long fixation by the theory of Von Mises was 230 MPa, and it was located in the rod area next to the L2 vertebra. The maximum stress obtained for short fixation was 274.24 MPa, and it was located in the pedicle screw on the T12 vertebra.


CONCLUSIONS
There were no significant differences between the two techniques, since the observed stresses are well below the flow stress of the material, ensuring good safety factor (ranging from 3.5 to 4.1).
Orthopedics and Traumatology Institute, Passo Fundo, Rio Grande do Sul, Brazil.
André Rafael
AR
Hübner
Daniel
D
Gasparin
Agenor Dias
AD
de Meira Junior
Charles Leonardo
CL
Israel
Jean Marcel
JM
Dambrós
Marcelo
M
Ribeiro
Leandro
L
de Freitas Spinelli
D001863:Bone Screws; D003198:Computer Simulation; D055119:Elastic Modulus; D005593:Fracture Fixation, Internal / Q000295:instrumentation / Q000379:methods*; D006801:Humans; D021621:Imaging, Three-Dimensional; D016268:Internal Fixators; D008159:Lumbar Vertebrae / Q000293:injuries* / Q000601:surgery; D008953:Models, Anatomic; D016103:Spinal Fractures / Q000601:surgery*; D013904:Thoracic Vertebrae / Q000293:injuries* / Q000601:surgery; D014057:Tomography, X-Ray Computed