O1362 INTRA-ARTICULAR STRESS DISTRIBUTION IN THE FEMORO-TIBIAL JOINT AFTER IMPLANTATION OF A TOTAL KNEE PROSTHESIS (TKA)

Abstract

Aims: Femoral component malalignment is known to lead to revision after Total Knee Arthroplasty (TKA). Little is known about the change of intraarticular stress distribution and the influence to compartmental instability due to malrotation. Moreover the influence of inlay design has never been characterized on a cadaver model. Methods: Eight human cadavers were selected. A holder was developed and constructed that allowed the femoral component to rotate along the femoral axis. After performing TKA (Scorpio) with a fixed and a mobile bearing PE inlay the specimens were tested in a servo-hydraulic machine (MTS). A Tekscan film device was installed between the inlay and the femoral component. Static and dynamic measurements with a constant quadriceps ligament force of 800 N were performed between 5°and 90° of knee flexion. The rotation of femoral component was changed between −15 and +15° in 5° incremental steps. Results: Malrotation causes a stress increase in the medial and lateral compartment. Internal malrotation of the femoral component causes higher stresses medially than laterally. A difference between the mobile and fixed bearing design was also observed. Conclusions: Internal femoral malrotation must be avoided because of higher stresses in the medial femoro-tibial compartment and instability in the lateral one.