Biomechanical evaluation of percutaneous anterograde and retrograde screw implantation for superior ramus pubis fractures: a finite element analysis.

OBJECTIVE

To evaluate the biomechanical characteristics of percutaneous anterograde and retrograde screw implantation for superior ramus pubis fractures.

METHODS

Mimics software was used to reconstruct the normal pelvis. 3-Matic software was used to establish a model for superior ramus pubis fracture, and percutaneous anterograde/retrograde screw implantation was used to simulate the treatment of a superior ramus pubis fracture. After material assignment by Mimics software, Ansys software simulated the force of a standing position with a 600 N load on an S1 vertebral endplate and then compared the mechanical stability.

RESULTS

After simulating the fracture at five points, the effect of anterograde and retrograde screw implantation on the displacement and stress of the pelvis and the left pubic bone were found to be similar. When anterograde screw implantation was used, screw displacement at each point was 1.10 mm, 1.04 mm, 1.10 mm, 1.10 mm, and 1.07 mm; the stress at each point was 14.95 MPa, 11.50 MPa, 18.60 MPa, 18.07 MPa, and 18.37 MPa. When retrograde screw implantation was used, screw displacement at each point was 0.62 mm, 0.62 mm, 0.70 mm, 0.76 mm, and 0.87 mm; and the stress at each point was 5.13 MPa, 4.03 MPa, 6.61 MPa, 9.74 MPa, and 11.55 MPa respectively.

CONCLUSIONS

When assessing the treatment of superior ramus pubis fractures from a biomechanical perspective, we found that if the distance between the fracture line and the insertion point is less than 70 mm, it is recommended to use retrograde screw implantation.