The stage of reconstruction of bone defects in revision total knee arthroplasty is one of the most crucial steps affecting the survival of the implant applied. The defect needs to be fully described first. Then, the type of the defect is identified using bone defect classification systems. The most frequently-used classification for this purpose is the bone defect classification by Anderson Orthopedic Research Institute (AORI). The decision of using a particular type of support in reconstruction is given according to bone defect classification. Small, contained defects are usually treated with a combination of bone cement and screw or with morselized allograft, whereas larger, uncontained defects require metal block and wedge augments, large structural allografts or highly porous metal metaphyseal cones. In severe casesof metaphyseal and diaphyseal bone defects, where none of these options are implemented, the last treatment option may be tumor reconstruction prosthesis.