Surgery may be considered even when only a portion of the knee surface has worn out.  Unicompartmental Knee Replacement (also called Knee Arthroplasty) is the partial replacement of the knee surfaces.  Using minimally invasive surgery (MIS) techniques, a partial knee replacement can be inserted through a smaller incision, with minimal interruption to the muscles and tendons around the knee.  The smaller incision and less invasive surgical approach allow for patients to recover more quickly and return home from the hospital within 1 – 2 days.  Unicompartmental Knee Replacement may allow better knee function for return to athletic activity.  Severe arthritis and deformity cannot be corrected.  Inflammatory arthritis (like rheumatoid) cannot be treated by partial replacement.  After Unicompartmental Knee Replacement surgery, arthritis can still develop in the other parts of the knee.  Recovery from the Unicompartmental Knee Replacement is quicker than from a Total Knee Replacement.