Development of Bioabsorbable Interference Screws: How Biomaterials Composition and Clinical and Retrieval Studies Influence the Innovative Screw Design and Manufacturing Processes - Biologically Responsive Biomaterials for Tissue Engineering - page 124

Fig. 6.12 Geometry for fi nite element analysis

Fig. 6.13 Total deformations for 25°/30° interference screw

The bone was fixed in all three directions on the exterior surfaces, and the contacts
between tendon, screw, and bone were considered bonded. For the experiment
design the fact that the forces in the reconstruction graft are collinear with the femo-
ral tunnel at 100° of flexion while the tibial tunnel remains collinear all through the
range of motion was taken into account.
The mechanical properties used for screw, bone, and tendon are presented in
Table 6.4 . The model was meshed using tetrahedral elements with six degrees of free-
dom per node. The total number of nodes was 115,859, the number of solid elements
was 67,105, and the number of contact elements was 24,636. The results of the finite
element analysis are also presented in Table 6.5 . FEM analysis showed that from the
investigated angle combinations, 25°/40° provides the best holding strength.