Finite Element Investigation of Hybrid and Conventional Knee Implants

Total Knee arthroplasty (TKA) procedures relieve arthritic pain and restore jointfunction by replacing the contact surfaces of the knee joint. These proceduresare often performed following arthritic degeneration of the joint causing thepatient pain. Cobalt-chrome, stainless steel (316L grade) and titanium alloys arewidely used in the majority of distal femoral implants in TKA procedures. The useof such stiff materials causes stress shielding (i.e. a lack of mechanical stressesbeing experienced by the bone surrounding the implant) leading to gradual boneloss and implant failure. The aim of this paper is to develop a new hybrid kneeimplant which combines a polymer-composite (CF/PA-12) with an existingcommercial implant system (P.F.C. Sigma ) made from stainless steel. Thishybrid implant is expected to alleviate stress shielding and bone loss bytransferring much more load to the femur compared to conventional metallicimplants. Results of the FEA simulations showed that the CF/PA-12 lined femoralcomponent generated almost 63% less in peak stress compared to the regularstainless steel component, indicating more load transfer to the bone andconsequently alleviating bone resorption.