It is also referred to as Unicondylar Replacement Surgery, or Knee resurfacing, and is a surgical procedure which involves the resurfacing of the worn out bony surface of the knee joint. In this, either the inside joint (medial); outside parts of the knee (lateral); or area between the knee cap and the upper front surface of the femur (patellofemoral) is replaced. This means only the damaged part of the knee cartilage is replaced with a prosthesis not all parts as in Total Knee Replacement Surgery.