The computer simulation shows the effect, if any, on the ageing/disease process on the articular cartilage during the forces encountered on a fully loaded knee bend. A finite element model of the patella was produced in which all four of the materials of the patella were taken into account with the addition of simulating the effect of the synovial fluid with a uniform distribution of compression springs acting on the articular surface. A parametric analysis was performed varying the mechanical properties of the articular cartilage to simulate the disease process reflecting changes in the structural composition with progressive degeneration. The results of the simulation indicate that the stresses imposed on the patella do not have an adverse effect. However, the stresses within the cartilage do increase accordingly.