Knee replacement is required when knee become painful and stiff due to degeneration of articular cartilage and altered biomechanics of the knee. One such condition is Osteoarthritis in which joint space is narrowed and obliterated; and knee has a deformity with crackling sound on movements. By this procedure damaged articular surface is replaced with artificial joint along with correction of the deformity. Unicondylar knee replacement is performed in the patients with early osteoarthritis where only one compartment of the knee is involved & there is no fixed deformity of the knee. Only damaged condyle is replaced. Revision knee replacement is performed when the previous knee replacement is causing trouble due to implant loosening, plastic wear, and infection or due to any other reason. Previous artificial knee is replaced with new one with extra features.