The knee joint is a very large and complex joint in the body. It consists of four bones called the femur, tibia, fibula and patella, which are connected by muscles, ligaments and tendons. The patella is a small bone in front of the knee that slides up and down in a groove in the femur while the knee bends and straightens. There is a type of cartilage in the knee called articular cartilage is a smooth shiny material that covers the bones in the knee joint and allows the knee bones to move easily while the knee bends and straightens. The knee is a vulnerable joint that bears a great deal of stress from everyday activities such as lifting and kneeling, and other high impact activities such as jogging and aerobics.

The following parts form the knee: * Tibia - shin bone or larger bone of the lower leg. * Femur - thigh bone or bone of the upper leg. * Patella - flat bone located in front of the knee joint.

One of the major causes of knee pain is osteoarthritis, this is the most common type of arthritis means inflammation of a joint, and in this case it would be arthritis in the knee. Osteoarthritis affects the cartilage in the knee which begins to degrade until it becomes fine cracks or form. After a long time the cartilage can become completely worn away that causes bones to rub together, resulting in knee pain.

Among the most common problems of the knee include: * Sprain or strain of the ligaments and muscles of the knee or usually, this occurs when the knee suffers a blow or a sudden twist. Often, the symptoms include pain, swelling and difficulty walking.

* Torn cartilage A knee injury can tear the menisci (pads of connective tissue that act as shock absorbers and also enhance stability). Cartilage tears can often occur with sprains. Treatment may involve wearing a brace during an activity to prevent further damage to the knee. May be called for surgery to repair the tear.

* Tendinitis- Inflammation of the tendons may occur as a result of overuse of a tendon during certain activities like running, jumping, or bicycling. Tendinitis of the patellar tendon is called jumper's knee. This condition is frequently seen in sports such as basketball, in which the force with which it hits the ground after a jump strains the tendon.

* Arthritis Osteoarthritis is the most common type of arthritis affecting the knee. Osteoarthritis is a degenerative process in which the joint cartilage gradually wears away, and usually affects middle-aged or older. You can be the result of excessive force on the joint such as repeated injury or being overweight.

Rheumatoid arthritis can also affect the knees by causing the joint to become inflamed and destroying the knee cartilage. Compared with osteoarthritis, rheumatoid arthritis tends to affect younger people.

What doctor's advice:

Doctors recommend treatments to reduce pain, improve range of motion of the knee and their functions that provide the ability to run, jump and play sports. These treatments include surgery for knee replacement most extreme cases, medications, nutritional supplements and educational options for less severe cases that allow them to get a comfortable position and sleep properly and reduce the pain of the knee.