A 3D-printed, personalized, biomechanics-specific beta-tricalcium phosphate bioceramic rod system: personalized treatment strategy for patients with femoral shaft non-union based on finite element analysis

BACKGROUND: Although double-plate fixation (DP), i.e., fixation with a combination of a main lateral plate (LP) and a support medial plate (MP), is a relatively mature method for treating femoral shaft non-union with bone defect causes complications. The purpose of this study was to evaluate LP fixation with a 3D-printed, personalized, biomechanics-specific β-TCP bioceramic rod system (LP + 3DpbsBRS) as an alternative with less collateral damage. METHODS: Structure-specific finite element modelling was used to simulate femoral shaft non-union with bone defects and treatment with an LP only as the blank control. Then, the peak von Mises stress (VMS), the VMS distribution, and the plate displacement were determined to compare the effectiveness of LP + CBG (cancellous bone grafting), DP + CBG, and LP + 3DpbsBRS under 850 N of axial force. RESULTS: Our results indicated that the peak VMS was 260.2 MPa (LP + 3DpbsBRS), 249.6 MPa (MP in DP + CBG), 249.3 MPa (LP in DP + CBG), and 502.4 MPa (LP + CBG). The bending angle of the plate was 1.2° versus 1.0° versus 1.1° versus 2.3° (LP + 3DpbsBRS versus MP in DP + CBG versus LP in DP + CBG versus LP + CBG). CONCLUSION: The 3DpbsBRS in the LP + 3DpbsBRS group could replace the MP in the DP + CBG group by providing similar medial mechanical support. Furthermore, avoiding the use of an MP provides better protection of the soft tissue and vasculature.