IN-VIVO DETERMINATION OF CONTACT AREAS AND PRESSURE OF THE FEMOROTIBIAL JOINT USING NONLINEAR FINITE-ELEMENT ANALYSIS

Objectives. A three dimensional finite element model of the femorotibi al 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 techn ique was used to model the geometry and mechanical testing had been pe rformed to quantify the material properties.Method. MR images were per formed on a normal adult knee joint, in extension position. An image p rocessing software developed in our laboratory allowed our model geome try to be constructed, and a pre-and post-processing software allowed us to develop a three-dimensional finite element model. Experimental c ontact area values were obtained using a method developed in our labor atory. Theoretical contact values, areas and hydrostatic pressure were obtained with a non-linear finite element computation using a non-lin ear software solver. Results. The results show a good agreement betwee n theoretical and experimental contact area values, Hydrostatic pressu re was found to be higher at the medial contact than at the lateral co ntact. Conclusion. This study validated the use of contact elements to quantify the contact areas. The model permitted the body weight simul ation to understand the role of the menisci. Relevance The clinical ap plication of the study was to develop a method evaluating the influcnc e of rotational abnormalities of the lower limbs on the knee joint at short- and long-term. This consisted of quantifying the contact area a nd pressure values and their migration. (C) 1998 Elsevier Science Ltd. All rights reserved.