The knee is a vulnerable joint that bears a great deal of stress from everyday activities such as lifting and kneeling, and from high-impact activities such as jogging and aerobics. Each bone end is covered with a layer of cartilage that absorbs shock and protects the knee. Basically, the knee is two long leg bones held together by muscles, ligaments, and tendons.
Tendons are tough cords of tissue that connect muscles to bones.
Ligaments are elastic bands of tissue that connect bone to bone. Other knee problems are a result of an injury or a sudden movement that strains the knee. Symptoms often include pain, swelling, and difficulty in walking. Cartilage tears can often occur with sprains. Treatment may involve wearing a brace during an activity to protect the knee form further injury.