Mechanical Stability of the Tibial Component in Total Knee Arthroplasty: a Comparison of three different Design concepts using Finite Element Analysis

Different causes could be behind the need for total knee arthroplasty (TKA), with osteoarthritis being the main one. With an ever-greater number of knee implants, the prosthetic market is looking for new technologies that could guarantee a satisfactory outcome while being as less invasive as possible. The focus of this study is to provide a comparison between three different tibial components, created starting from the same model, using the finite element method (FEM) to analyze the directional displacements and the Von Mises stress and strain in static condition. The components' behavior immediately after the implant is of special interest for this study. The first component has been modeled for this case study and, instead of a single keel, its structure presents several rounded pyramidal elements of different lengths. The second component, inspired by an already existing model, presents a keel and four extra pegs. Finally, the third model presents no pegs and a larger cylindrical keel that resembles models used for revision implants. The analyses of these three models were made under the condition of primary fixation, shortly after the implant, and secondary fixation, after some weeks from the surgery. In particular, the most important purpose of this study is to analyze the difference in rotational stability between the three models. It was questioned if the multi-body structure could present less micro-movements in a primary fixation condition compared to the two models presenting a single keel. The results showed a better rotational stability for the multi-body component, but more evident stresses compared to the single-keel components. In secondary fixation, the results do not diverge much between each component. Ultimately, this study shows that a multi-body component could be worthy of further analysis as it presents similar rigidity to already existing models with a single keel, while performing better in a situation where the treated knee is subjected to torque.