Abstract
Background: We undertook a comparative biomechanical study of type B1 fractures around the femoral prosthesis following cemented hip arthroplasty using the Ortho-Bridge System (OBS) and a locking compression plate/locking attachment plate structure (LCP+LAP), and aimed to determine the effectiveness and advantages of the OBS when treating this fracture type. Methods: An OBS fixation model was designed based on OBS and LCP+LAP fixation characteristics. The LCP+LAP combination (Group A) and three different OBS combinations (Groups B, C, and D) were used to fix a B1 fracture model with a femoral periprosthetic fracture. Axial compression and torsion experiments were then performed using simple and comminuted fracture models. We conducted axial compression failure, model stiffness, and torsion angle tests, and tested the vertical load of final failure. Results: When simulating simple oblique fractures, no significant difference was found in terms of stiffness between the four groups in the axial compression experiment (P = 0.257). The torsion angle of the LCP+LAP system was significantly higher than that of the OBS (P < 0.05); however, there was no significant difference in the torsion angle between the OBS combinations (P > 0.05). Axial compression experimental data showed that stiffness in the three OBS combinations was higher than that in the LCP+LAP system (P = 0.000). Torsion angles of the three OBS combinations were smaller than those of the LCP+LAP system (P < 0.05). In the axial compression failure test, the fixed failure mode in the LCP+LAP system involved destruction of the contact cortex at the fracture site, while the failure modes in the three OBS combinations involved destruction of the contact cortex at the fracture site and the fracture around the screws above the osteotomy. Conclusion: Compared with the LCP+LAP, the OBS showed superior biomechanical results. Furthermore, the OBS has the advantage of multiple choices and high flexibility of combinations. Stress dispersion was helpful in avoiding internal fixation failure during early postoperative functional exercise.