Finite Element Analysis Model to Study the Dynamics of Valgus Knee After Total Arthroplasty

Total knee arthroplasty (TKA) is a successful procedure in the field of orthopedic surgery. Behind its application, there is its strict correlation to the most common form of arthritis: osteoarthritis (OA), an inflammatory condition that occurs when one or many joints undergo degenerative changes. Although TKA remains a reliable surgery in patients suffering from debilitating advanced degenerative arthritis knee, it has been reported that approximately 20% of patients are dissatisfied after the surgery. A possible reason for this discontent could be the presence of some deformities i.e., valgus deformity. The most common complaint after TKA is abnormal patellar tracking. Obtaining proper kinematics of the patellofemoral joint is difficult to study starting from in vitro analysis. Thus, since the complexity of knee kinematics has always challenged and fascinated the scientific community, the researchers have explored other tools to better understand the behavior of the knee. In this context, finite element analysis (FEA) has made its way. Even though the FEA has been largely applied in the field of orthopedic surgery, some aspects remain untreated. Thus, the present work aims to apply the FEA in the case of valgus knee misalignment to assess which could be the pitfalls of the cruciate-retaining (CR)-TKA prosthesis and to obtain the kinematics pattern of the patellofemoral joint. The results obtained from the FEA are encouraging. Firstly, it has been pointed out an increase of the contact between the femoral component and patella with the rise of flexion angle. The analysis of von Mises stresses on the insert has revealed an abnormal distribution between the lateral and medial plateau at all flexion angles. The patellofemoral trends have been computed to assess the kinematics. From the reported findings it can be inferred that the finite element model employed in this work can study the dynamics of the postoperative valgus knee. This may be a step toward new research aimed at the development of TKA designs able to reduce the patient’s dissatisfaction.