Biomechanical comparison of transdiscal fixation and posterior fixation with and without transforaminal lumbar interbody fusion in the treatment of L5-S1 lumbosacral joint
Ozalp, Hakan and Ozkaya, Mustafa and Yaman, Onur and Demir, Teyfik
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Abstract
Transdiscal screw fixation is generally performed in the treatment of
high-grade L5-S1 spondylolisthesis. The main thought of the study is
that the biomechanical performances of the transdiscal pedicle screw
fixation can be identical to standard posterior pedicle screw fixations
with or without transforaminal lumbar interbody fusion cage insertion.
Lumbosacral portions and pelvises of 45 healthy lambs' vertebrae were
dissected. Animal cadavers were randomly and equally divided into three
groups for instrumentation. Three fixation systems, L5-S1 posterior
pedicle screw fixation, L5-S1 posterior pedicle screw fixation with
transforaminal lumbar interbody fusion cage insertion, and L5-S1
transdiscal pedicle screw fixation, were generated. Axial compression,
flexion, and torsion tests were conducted on test samples of each
system. In axial compression, L5-S1 transdiscal fixation was less stiff
than L5-S1 posterior pedicle screw fixation with transforaminal lumbar
interbody fusion cage insertion. There were no significant differences
between groups in flexion. Furthermore, L5-S1 posterior fixation was
stiffest under torsional loads. When axial compression and flexion loads
are taken into consideration, transdiscal fixation can be alternatively
used instead of posterior pedicle screw fixation in the treatment of
L5-S1 spondylolisthesis because it satisfies enough stability. However,
in torsion, posterior fixation is shown as a better option due to its
higher stiffness.... Show more Show less