Exploration of articular cartilage biomechanical response during gait of patient with knee osteoarthritis using finite element models

Abstract

Knee osteoarthritis (OA) is one of the most prevalent forms of arthritis and one of the leading causes of disability. The pathological traits consist of articular cartilage degradation and bone thickening, among other factors. Since evaluating the changes in the cartilage is difficult to accomplish via medical tests, finite element (FE) models are arising as an alternative. However, they are too simple and do not consider changes through the gait cycle. Thus, the aim of this project is to evaluate the articular cartilage response of knee osteoarthritic patients during gait cycle through a FE model, using data from real patients. Three knee condition were evaluated: 1) healthy, 2) with OA referred to conservative treatment, and 3) with OA referred to surgery. For each condition, knee reaction force, rotation angles and time of full gait cycle was obtained from data of real patients. The biomechanical response was addressed by using a 3D knee FE model that considers the femur and tibia as rigid bodies, and the cartilages and menisci as composition-based materials. Two gait simulations were performed: a) full extension, and b) with angles of rotation. Emphasis is placed on contact pressure and water and proteoglycan content at cartilage zones most affected by OA according to clinical observations. Lateral articular cartilage receives significantly more contact pressure than the medial in all conditions. Nonetheless, an average pressure difference between both cartilages changes from 36.86% to 4.92% when cases 1) and 3) are compared. Similar outcomes were observed water and proteoglycans content. When rotation is considered, OA patients showed cartilage-cartilage contact, aspect not seen for healthy condition. Overall, this study provides valuable information for clinician in OA treatment decision making. Moreover, the effect of the biomechanical environment found in this study on cartilages cells need to be further study, to develop novel strategies to face knee OA.