Knee osteoarthritis, also known as knee arthritis, is a degenerative condition characterized by the breakdown or inflammation of the cartilage within the knee joint. This degradation causes the bones of the joint to rub against each other, leading to symptoms such as pain, stiffness, and swelling. As the cartilage surface becomes rough and worn, it exacerbates this friction, consequently restricting the knee's range of motion. The articular cartilage normally covers the ends of the femur (thigh bone), tibia (shin bone), and the back of the patella (kneecap). When this protective cartilage erodes, the joint space between the bones narrows. In advanced stages of knee osteoarthritis, the cartilage may completely wear away, resulting in direct bone-on-bone friction.