Biodegradable polymeric materials such as Polylactic Acid (PLA) and Polycaprolactone (PCL) are proven to be a good choice in the design of biopolymeric devices for tissue engineering applications for osteochondral implants such as scaffolds. The behaviour of these materials has been submitted to several studies and numerical models have been developed to predict the behaviour of such materials when implanted in the damaged tissue. When talking about amorphous polymers, there is a predominance of the degradation process of the polymeric material, and the surface erosion process. Here, a novel stable probabilistic-deterministic numerical tool developed on FreeFem++ to predict the erosion and degradation behavior of polymeric materials of biodegradable polymers is presented. The erosion model is based on a stochastic approach using cellular automated distribution. The degradation model is based on the Fick Law of diffusion of materials, whereas the surface erosion model is considered an stochastic process, and modelled using a Monte Carlo simulation technique. Furthermore, to validate the erosion mechanism, a porosity function is described, in order to compare the results with the experimental data. In order to gain more stability in the methodology, a Fictitious Domain Technique is implemented in order to describe the changes on the boundary during the erosion process.