Fig 1.
Finite element model and loading/boundary condition of the spinopelvis and implant.
Image (a) shows the anterior view with ligaments, and (b) shows the posterior view with ligaments. Image (c) shows the sagittal plane view, and (d) shows the S2AI screw. Image (e) shows the iliac screw, and (f) shows the 15° head angle. Image (g) shows the 30° head angle, and (h) shows the loading/boundary condition.
Table 1.
Material properties of the tissues and implants.
Table 2.
Material properties of the lumbar and pelvic ligaments.
Fig 2.
Classification according to the mesh densities to evaluate the sensitivity of the elements.
Image (a) shows the coarse mesh, and (b) shows the medium mesh. Image (c) shows the fine mesh.
Table 3.
Analysis of the state and influence on the interpretation by densities of the mesh.
Fig 3.
Comparison of the experimental data from the literature with the simulation results of this study.
Fig 4.
von Mises equivalent stress distribution of the screw in the spinopelvic model with the iliac screw under various loading conditions.
Fig 5.
von Mises equivalent stress distribution of the screw in the spinopelvic model with the S2AI screw (75-mm screw length and 15° head angle) under various loading conditions.
Fig 6.
von Mises equivalent stress distribution of the screw in the spinopelvic model with the S2AI screw (90-mm screw length and 30° head angle) under various loading conditions.
Fig 7.
Maximum equivalent stress in the two types of screws.
Image (a) shows the iliac screw, and image (b) shows the S2AI screw.
Fig 8.
von Mises equivalent stress distribution of the bone around the iliac screw under various loading conditions.
Fig 9.
von Mises equivalent stress distribution of the bone around the S2AI screw (75-mm screw length and 15° head angle) under various loading conditions.
Fig 10.
von Mises equivalent stress distribution of the bone around the S2AI screw (90-mm screw length and 30° head angle) under various loading conditions.
Fig 11.
Maximum equivalent stress in the adjacent bone of the screws.
Image (a) shows the iliac screw, and image (b) shows the sacrum with the S2AI screw. Image (c) shows the ilium with the S2AI screw.
Table 4.
Maximum von Mises equivalent stress values of the screws and the bone around the screw under compression load.
Table 5.
Maximum von Mises equivalent stress values of the screws and the bone around the screw under compression and flexion loads.
Table 6.
Maximum von Mises equivalent stress values of the screws and the bone around the screw under compression and extension loads.
Table 7.
Maximum von Mises equivalent stress values of the screws and the bone around the screw under compression and rotation loads.