A cartilage injury in the knee involves damage to the protective tissue that cushions the joint. This can result from various causes, including sports injuries, trauma, or wear and tear over time. The symptoms often include pain, swelling, and difficulty moving the knee smoothly. Cartilage does not have a good ability to heal on its own, so prompt and appropriate care is essential. Treatment options may range from rest, ice, and physical therapy to more advanced interventions such as arthroscopic surgery or, in severe cases, knee replacement.