Journal of the American Academy of Orthopaedic Surgeons January 2008, Volume 16, Issue 1 Todd Borus, MD and Thomas Thornhill, MD Recent increased interest in less invasive surgical techniques has led to a concurrent resurgence in unicompartmental knee arthroplasty. The procedure has evolved significantly over the past three decades. Proponents of unicompartmental knee arthroplasty cite as advantages lower perioperative morbidity and earlier recovery. Both clinical outcome and kinematic studies have indicated that successful unicompartmental knee arthroplasty functions closer to a normal knee. Recent reports have demonstrated success in expanding the classic indications of unicompartmental knee arthroplasty to younger and heavier patients. Both fixed- and mobile-bearing implants can yield excellent clinical outcomes at >10 years, but with different modes of long-term failure. Proper execution of surgical technique remains critical to optimizing outcome. Long-term studies are needed to appropriately define the role of less invasive unicompartmental surgical approaches as well as the role of computer navigation.