Modeling and Numerical Analysis of a Cervical Spine Unit - Biologically Responsive Biomaterials for Tissue Engineering - page 163

Fig. 7.24 Strain variation along the bone threads for Sr3 superior and inferior mountings
Fig. 7.25 Strain variation along the bone threads for Sr3 superior and inferior mountings
The third set of simulation results put on evidence the Sr3 hybrid screw behavior.
The values of the strains distributed along the superior thread hole (see Fig. 7.24 )
are sensibly higher than in the Sr2 case, but smaller than in the Sr1 case. In the
inferior section of the hole, the strains almost overlap with the second case results.
As Fig. 7.25 presents, the strain variations along the threads are less present in
this case. This indicates us a better strain distribution on the bone interface. This
screw type represents a geometrical compromise of the thread's depth, pitch, and
profile, and proves to represent a good compromise from the strain distribution
point of view.
The ability of strain distribution in bones is better highlighted by representing the
performances of the three screws on the same graph (see Fig. 7.26 ). Here are pre-
sented the behaviors of the superior bone interfaces for each screw mounting, and
inferior bone interfaces.
The second aspect of this simulation is focused on the stresses acting at the
bone-screw interface. Because of the high mechanical strength of the bone screws,
they exhibit larger stresses than the bone structure, making no difference of screw