The goal of this study is to analyze mechanical behavior of a new scaffold composed of PLA/bTCP in revision knee arhtroplasty (RKA). For this purpose, finite element models of RKA was developed to study the importance of the geometry of bones, the fixation length of the stem, height of the scaffold, and the type of defect (segmental and cavitary). The results of this study indicate that the height of the scaffold is the most important of all and the fixation length of stem is the least important parameter for failure of scaffold. This numerical model also gives a range of average volumetric strain. Volumetric strain of the scaffold is important for bone formation inside the scaffold since it represents the amount of fluid flow. The results obtained using this model will be used later in in vivo experiments.