Postoperative analysis of the biomechanical effect of TKA using the finite element method

Abstract

The accuracy of the implant positions and the alignment of the lower leg are important in total knee arthroplasty(TKA). The stress distribution may affect the lifespan of the artificial joints. In this study, 3D postoperative extension analyses of TKA using the finite element method were performed to estimate the stress patterns of 3 patients after the operation. Before the surgery, subject-specific 3D models of the patients’ tibiofemoral joints were reconstructed from CT images and implant components obtained using a 3D scanner. The relative positions of the models of different parts were calculated using a 2D-3D medical image registration technique on the basis of dual X-ray images taken after operations. It was found that stress distribution on the polyethylene insert part surface was significantly affected by the extension gaps, while the stress distribution on the bone cut face was more influenced by the relative cutting angles. Our methods could be used to postoperatively evaluate TKA, which may help in the comprehension of key issues in operations and in the prediction of the lifespan of artificial joints by determining how much of the polyethylene insert placed between the 2 metal implants wears away over time.