In this
study some 3D nonlinear finite element models of the intact ligamentous
lumbar units were constructed. The analysis accounts for both material
and geometric nonliniearities. Two commercial types of pedicle screw
systems were used to simulate the stabilizing process. Load-displacement
behavior of the stabilized models and stress distribution in various
spinal structures were compared with those of intact models. In
addition, a parametric stabilized model was developed to evaluate the
effects of variation in material properties of the graft and cancellous
bone, pedicle morphometry and position of the graft on the results.
Stress distribution in the implants was also investigated as a function
of variation in insertion technique to determine how the risk of pedicle
screw breakage is affected by changes in screw insertion depth, height
and angle within the pedicle. Results of parametric model indicated that
pedicle morphometry has a minor effect on the stresses in the pedicle
screw while these stresses can strongly affected by surgical technique.
F.
Farahmand
,
H.
Hosseini Nasab
M. H. Karegarnovin
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