In vivo determination of contact areas and pressure of the femorotibial joint using non-linear finite element analysis.

OBJECTIVES: A three dimensional finite element model of the femorotibial joint was developed from MR images in order to quantify in vivo the articular contact.
BACKGROUND: Most of femorotibial joint models were elaborated from in vitro experiments. The stereophotogrammetric technique was used to model the geometry and mechanical testing had been performed to quantify the material properties.
METHOD: MR images were performed on a normal adult knee joint, in extension position. An image processing software developed in our laboratory allowed our model geometry to be constructed, and a pre-and post-processing software allowed us to develop a three-dimensional finite element model. Experimental contact area values were obtained using a method developed in our laboratory. Theoretical contact values, areas and hydrostatic pressure were obtained with a non-linear finite element computation using a non-linear software solver.
RESULTS: The results show a good agreement between theoretical and experimental contact area values. Hydrostatic pressure was found to be higher at the medial contact than at the lateral contact.
CONCLUSION: This study validated the use of contact elements to quantify the contact areas. The model permitted the body weight simulation to understand the role of the menisci. RELEVANCE: The clinical application of the study was to develop a method evaluating the influence of rotational abnormalities of the lower limbs on the knee joint at short- and long-term. This consisted of quantifying the contact area and pressure values and their migration.