Kinetics/Kinematics of Intact and Arthritic Knee Cartilages and A Novel Approach to Enhance Wear Characteristics of Uhmwpe Tibial Inserts for Prosthetic Knee

Abstract

Osteoarthritis is a severe and progressive disorder that affects the knee joint due to cartilage degradation from daily rigours activities. Articular cartilage is more susceptible to knee arthritis compared with other soft tissues. Hence, understanding degradation phenomena are more critical and require understanding the tissue's stress fields. Experimental methods have limitations, such as inaccessible cadaveric knees and obtaining in-vivo data from intact and arthritic knees is difficult and imprecise. Hence the numerical method is the most effective technique for understanding the cartilage’s mechanical behaviours under different conditions. The cartilage constituents make the cartilage geometrically and mechanically heterogeneous. A 3D finite element knee joint model is used to compute the articular cartilage response during multiple activities. Various material models are available to model the heterogeneity of articular cartilage. Multiple constitutive models are compared for the prediction of mechanical response. In addition, the influence of the inhomogeneous distribution of collagen fiber in cartilage is investigated for intact and arthritic knee kinematics cases. In reality, the cartilage structure is heterogeneous, and the computational study shows the importance of heterogeneity in the mechanical response of the knee joint. Conventionally the knee implant-bearing material (UHMWPE) is homogeneous. Incorporating the heterogeneous characteristics in the bearing material may help enhance the implant's mechanical characteristics. The proposed model generates property-modulated characteristics in the bearing material using gamma irradiation, and the heterogeneous characteristics are incorporated into the knee implant. UHMWPE's tribological and chemical characteristics are analysed experimentally, and the wear rate and volume are calculated. The wear rate decreases as the radiation dose increase to a particular level and then increases as the dose increases further. Compared with the conventional technique, a reduction in wear rate for the material is observed for the proposed technique. Also, the hardness of the UHMWPE is measured, and its value increases as the irradiation dose increases.