Abstract
The paper presents the study on the retrieved polyethylene components from total knee prosthesis. For the longevity of total knee arthroplasty it is very important to predict the polyethylene wear and optimize the prosthetic design. The functionality of the total knee prosthesis is affected by contact stress, sliding motion and kinematics of the prosthesis components. The most important factors which cause long-term failure of a prosthetic joint are: macroscopic fracture of the metallic components, polyethylene component wear, corrosion process, and osteolysis. Even the prosthesis development over the past decade has included improvements in implant designs and use of advanced biomaterials, is still difficult to replace some classic biomaterials. Ultra-high molecular-weight polyethylene (UHMWPE) has been the primary material for the articulating surface in prostheses for nearly 40 years. Even now there are a number of problems with the UHMWPE, which cause troubles for the patients. On retrieved polyethylene components, 7 different defects were observed (burnishing, scratching, pitting, surface deformation, delamination, abrasion, bone-cement debris) using stereomicroscopy and scanning electron microscopy. It was found that the cement debris on the surface of the polyethylene explants reduce dramatically the total knee prosthesis lifetime and using FTIR analysis was clearly identified the presence of the cement debris on the surface of polyethylene component. Delamination and abrasion contributed the most to the total amount of damage; according the Hood model, the most damage area of the polyethylene components was seen at the medial (1, 4 sections) and lateral sides (5, 8 sections), followed by the anterior and posterior sides.
Keywords: polyethylene; knee prosthesis; failure; microscopy; defects