INFLUENCE OF THE GEOMETRY OF THE ATTACHING PEGS OF THE FEMORAL COMPONENT OF A KNEE PROSTHESIS

摘要

Several factors such as instability, misalignment, 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. Then, the study, modification and improving of the simulation methods to analyze implants is a subject of the most concern. Thus, this work is focused in the analyses of the influence of the geometry and inclination of the attaching pegs in the femoral component of knee implants. The aim is to evaluate the geometry of the implant stem to improve the stresses distribution and to increase the implant lifespan. Stresses distribution at the attaching pegs of the femoral component, by considering several combinations of diameters, lengths and inclinations, have been analyzed using finite element analysis (FEA). The analysis was conducted for the D = 8 mm, L = 13 mm and θ = 0°, in three different positions of the gait cycle. The variation of the geometry of the attaching pegs generated changes in the stresses distribution in bone. As the diameter increases, the stresses decrease in the femur. The medial areas of the implant appear to be the most likely regions to show bone resorption.