Femur Biomechanical Changes Caused by Femoral Stem Extension Implant in Total Knee Arthroplasty / 天津医药

ABSTRACT

Objective To evaluate the femur biomechanical changes of finite analysis with different femoral stem ex-tension implants in total knee arthroplasty (TKA). Methods The full-length femoral CT scan was performed in selected healthy volunteers. The femoral digital model was established with Mimics 10.0 and Geomagic Studio 10.0 software. The models of femoral prosthesis and stem extension implant were created by laser scanner. According to the common three hip loading modes (1 586 N, 1 690 N and 2 132 N), the maximum principal stress (MPS), the maximum principal elastic deforma-tion (MPES) and MPES distribution changes were recorded and analyzed by three-dimensional finite element analysis with ANSYS Workbench13.0 software. Results The MPS values before TKA were 98.54, 147.36 and 143.51 MPa respectively when values of femoral head loading were 1 586 N, 1 690 N and 2 132 N. With the increase in the length of the femoral pros-thesis extension rod, the MPS and MPES showed a decreasing trend. There was a positive correlation between free femur ra-tio (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 than 120 mm.