A Novel Anatomical Locking Guide Plate for Treating Acetabular Transverse Posterior Wall Fracture: A Finite Element Analysis Study

Objective To improve the treatment of the acetabular transverse posterior wall fracture (ATPWF), a novel anatomical locking guidance plate (NALGP) was designed and compared with traditional fixations using finite element analysis. Methods The ATPWF model was constructed using the three-dimensional finite element model of the half pelvis via the Mimics software and three internal devices were used to fix this model: the posterior-column locking plate with anterior-column screws (PCLP), double-column locking plates (DCLP), and NALGP. Next, mesh division was conducted by solid 187 tetrahedral elements in the workbench software. After defining the boundary condition and material properties, each assembly model was loaded in an increasing manner with a downward vertical force of 200, 400, and 600 N, respectively. The loading force was directed at 45 degrees upward in the coronal plane and 25 degrees backward in the sagittal plane. Finally, the stress distribution and stress peak of plates and screws were measured and evaluated, and the displacement of fracture fragments under different loading force was assessed among the three groups. Results For stress distribution, it was found that the stress mainly acted on the posterior-column plate, especially concentrated at the middle and lower section of the plate in all three groups after fixation on the ATPWF. In addition, most stresses of screws appeared on the lag screws instead of the common screws. The common screws in the NALGP group experienced larger stresses under all loading force, while those in the DCLP group withstood less stresses compared to those in the PCLP group. For the displacement of fracture fragments, the NALGP group were found to have less fracture fragment displacements than the PCLP group, but had comparable results to DCLP at both the transverse fracture and the posterior wall fracture sites. Conclusion The newly-designed fixation device showed superiorities on fracture stabilization over PCLP, but had comparable stability to DCLP. This suggests that the DCLP might be unnecessary for treating ATPWF in some instances because it might cause bigger surgical trauma and blood loss.