The decision depends on how much of the knee is affected by arthritis or damage, confirmed through weight-bearing X-rays and a physical exam evaluating the joint's range of motion and stability. Partial knee replacement is generally only appropriate when damage is confined to one compartment and the surrounding ligaments, particularly the ACL, remain intact. It is not the right option for every patient with knee arthritis, even if it sounds like the less invasive choice. Your surgeon will explain specifically why one option fits your case better than the other, based on your imaging.