Knee pain is very common. It is most common among athletes. There are more than 700,000 total knee replacement surgeries every year in the U.S. The most common causes of knee pain include:

·       Sprained ligaments

·       Meniscus tears

·       Tendonitis

·       Runner's knee

Other common causes:

·       Patellofemoral pain syndrome. Often results from issues associated with muscle imbalance, tightness, and alignment of the legs, rather than an injury.

·       Osteoarthritis. Common among athletes and non-athletes alike who are over age 50.

·       Osgood-Schlatter Disease. Causes a painful bump below the knee, where a tendon from the kneecap connects to the shin. Caused by overuse and irritation at the tendon insertion known as the tibial tubercle.

·       Dislocated kneecap (or patellar dislocation). This is when the kneecap slides out of position, causing knee pain and swelling.

·       Iliotibial band syndrome. The iliotibial band is irritated by overuse, it can become inflamed and cause pain on the outer side of the knee.

·       Bursitis. Overuse can irritate the bursa overlying the knee cap, causing pain and swelling.

·       Patellar tendonitis. This condition results from inflammation of the tendons surrounding your knee. Tendons are tough bands of tissue that connect muscles to your bones. Overuse can make the tendons inflamed and sore. The most common type of patellar tendonitis is called ''jumper's knee.''

·       Loose bodies. Sometimes, a knee injury can break loose cartilage. These pieces can get stuck in the joint, causing it to freeze up and producing pain and swelling.