Tendinitis
Tendinitis is a common knee injury that arises when the tendons in the knee become irritated and swollen from the rigors of running, especially on hard surfaces such as roadways. Tendons in the kneecap, or patella, are often inflamed in runners, which can result in pain in the knee. Sometimes both knees can be affected by tendinitis, which makes the knee swollen in the front or below the area of the kneecap. This pain will be worse when someone tries to run, and it can make it difficult to simply extend the knee into a straightened position.
Bursitis
Repeated running and wear and tear can precipitate bursitis in the knee, an injury that inflames the bursar sacs. These small, fluid-filled pouches cushion the knee to allow the ligaments and tendons within it to move sleekly over the joint, but bursitis makes this process painful. The knee can feel warm, be swollen and red, and hurt even while the individual is not using it. Stiffness and noticeable pain when going up or down the stairs are signs of bursitis. In rare cases the bursar sacs can become infected, which comes with symptoms such as fever and severe pain.
Dislocated Kneecap
A particularly painful runner's injury is the dislocated kneecap. If the patella bone on the front portion of the kneecap happens to slip, the runner will experience significant pain and swelling and be unable to walk or keep the knee straight without great difficulty. When a kneecap is dislocated, the medical term is a patellar subluxation. The bone usually will move to the outer sides of the knee, and in many cases even after this problem is treated the knee will have chronic pain.
Iliotibial Band Syndrome
If the ligament that runs from the outer part of the pelvic bone all the way to the outer portion of the tibia becomes tight from overuse, then the runner may have iliotibial band syndrome. This tendon is called the iliotibial band, and when this occurs this band starts to rub on the outer part of the femur. Symptoms of iliotibial band syndrome include a burning pain that long-distance runners will feel on their outer knee, and pain when climbing and/or descending stairs. The knee will not be compromised in relation to its range of motion, and there will be little if any swelling.
Runner's Knee
Chondromalacia of the patella is the medical language that describes pain that occurs between the femur and the patella. Runners with arthritis or those with a barely recognizable misalignment of the patella can suffer from this knee injury. The knee becomes very painful when you get up from a sitting position, use the stairs or sit for an extended span of time. The knee may feel as if is "grinding" when you try to straighten it out. This injury is also called "runner's knee."
