| Objective To compare the mechanical performance of the bridge combined fixation system (BCFS) with traditional plate screw fixation (PSF) in midshaft clavicle fractures through finite element analysis. The aim was to evaluate the biomechanical stability and stress distribution characteristics of the BCFS under simulated loading conditions and to explore its potential advantages in clinical application. Methods Using the normal clavicle 3D CT data from a healthy volunteer, a model of a midshaft transverse clavicle fracture was constructed using dedicated software. Eight internal fixation configurations were designed: BCFS round bars (4 mm diameter) placed superiorly and anteriorly, PSF placed superiorly and anteriorly, BCFS double bar fixation, BCFS flat bars (4 mm ×8 mm oval cross-section) placed superiorly and anteriorly, and intramedullary nail fixation. The models were subjected to compression, torsion, and three-point bending stress tests. Evaluation indicators included the maximum equivalent stress of the fixation device and the maximum displacement of the fracture end to test the stress distribution and fracture end stability under different fixation methods. Results The flat bar BCFS fixation showed superior parameter performance compared to the traditional PSF, which in turn was superior to the single 4 mm diameter round bar BCFS fixation. Under a compressive load of 200 N, the maximum stress for the anteriorly placed flat bar BCFS fixation was 210.92 MPa with a displacement of 0.15 mm, outperforming the anteriorly placed PSF of 292.46 MPa and 0.16 mm and the anteriorly placed 4 mm round bar BCFS of 720.6 MPa and 0.72 mm. Under torsional loading, the maximum stress for the superiorly placed flat bar BCFS fixation was 27.36 MPa at 0.04 mm displacement, which was not only lower than the superiorly placed PSF's 28.62 MPa at 0.07 mm, but also significantly lower than the superiorly placed 4 mm round bar BCFS's 50.97 MPa at 0.13 mm. Under three-point bending loading, the maximum stress for the superiorly placed flat bar BCFS fixation was 27.36 MPa with a displacement of 0.04 mm, not only lower than the superiorly placed PSF's 28.62 MPa and 0.07 mm, but also significantly lower than the superiorly placed 4mm round bar BCFS's 50.97 MPa and 0.13 mm. Under three-point bending load, the maximum stress and displacement for superiorly placed flat bar BCFS fixation were 217.98 MPa and 0.37 mm respectively, lower than the superiorly placed PSF's 253.47 MPa and 0.37 mm, and significantly better than the superiorly placed 4 mm round bar BCFS's 332.52 MPa and 0.41 mm. Conclusion BCFS offers a wide range of fixation options for midshaft clavicle fractures, allowing for the use of appropriate BCFS configurations for different types of fractures. This study demonstrates the advantages of BCFS fixation in terms of implant stress and fracture end displacement, providing a wider range of choices compared to traditional PSF. It combines the benefits of avoiding PSF's rigid fixation and the inadequacies of intramedullary nail fixation, offering a more biomechanically robust solution that promotes fracture healing. |
