Abstract:

[Abstract]   Objective   To evaluate the femur biomechanical changes of finite analysis with different femoral stem extension implants in total knee arthroplasty (TKA). Methods   The full- length femoral CT scan was performed in selectedhealthy volunteers. The femoral digital model was established with Mimics10.0and Geomagic Studio10.0software. The models of femoral prosthesis and stem extension implant were created by laser scanner. According to the common three hiploading modes (1586N,1690N and2132N), the maximum principal stress (MPS), the maximum principal elastic deformation (MPES) and MPES distribution changes were recorded and analyzed by three-dimensional finite element analysis with ANSYS Workbench13.0software. Results   The MPS values before TKA were98.54, 147.36and143.51MPa respectively when values of femoral head loading were1586N,1690N and2132N. With the increase in the length of the femoral prosthesis extension rod, the MPS and MPES showed a decreasing trend. There was a positive correlation between free femur ratio (FFR) and MPES (P<0.05). The MPES distribution was gradually concentrated at the top point of femur stem extension implant with the increase in the length of the femoral prosthesis extension rod. Conclusion   The values of MPS and MPES were gradually decreased with the increase in the length of the femoral stem extension implant. There was a positive linear correlation between FFR and MPES. The stress concentration was focused obviously at the top end of femoral stem extension implant with its length more than120mm.

Key words: arthroplasty, replacement, knee, knee prosthesis, finite element analysis