Failures of the Dual Articular knee prosthesis due to fracture of the polyethylene post

TO WHAT EXTENT THE COMBINATION OF STEM LENGTH AND STEM INCLINATION DO AFFECT THE PERFORMANCE OF THE TIBIAL COMPONENT IN KNEE IMPLANTS?

Mechanical loosening, instability, mechanical fractures and poor quality of bone are some factors that strongly influence the deterioration of knee implants. After a total knee replacement (TKR), proximal tibial bone suffers a resorption due to stress-shielding caused by the implant. The formation of weakening bone zones and loss of bone is one of the most clinical concerns. The aim of this work is to evaluate the geometry of the implant stem to improve the implant lifespan. A three-dimensional model of the tibial component has been generated using computerized tomographies (CT) reconstruction and CAD software. Stresses distribution at the interface bone-implant considering several combinations of stem lengths and stem inclinations have been analyzed using finite element analysis (FEA). High levels of resorption risk have been observed, when using different stem-lengths and varus inclination.