DefinitionAnterior knee pain is pain that occurs at the front and center of the knee. It refers to many different problems, including:Chondromalacia of the patella -- the softening and breakdown of the tissue (cartilage) on the underside of the kneecap (patella)Runner's knee (sometimes called patellar tendinitis)
Alternative NamesPatellofemoral syndrome; Chondromalacia patella; Runner's knee; Patellar tendinitis; Jumper's knee
Causes, incidence, and risk factorsYour kneecap (patella) sits over the front of your knee joint. As you bend or straighten your knee, the underside of the patella glides over the bones that make up the knee.Strong tendons help attach the kneecap to the bones and muscles that surround the knee. These tendons are called:The patellar tendon (where the kneecap attaches to the shin bone)The quadriceps tendon (where the thigh muscles attach to the top of the kneecap)Anterior knee pain begins when the kneecap does not move properly and rubs against the lower part of the thigh bone. This may occur because:The kneecap is in an abnormal position (also called poor alignment of the patellofemoral joint)There is tightness or weakness of the muscles on the front and back of your thighYou are doing too much activity that places extra stress on the kneecap (such as running, jumping or twisting, skiing, or playing soccer)You have flat feetAnterior knee pain is more common in:People who are overweightPeople who have had a dislocation, fracture, or other injury to the kneecapRunners, jumpers, skiers, bicyclists, and soccer players who exercise oftenTeenagers and healthy young adults, more often girlsOther possible causes of anterior knee pain include:ArthritisPinching of the inner lining of the knee during movement (called synovial impingement or plica syndrome)
SymptomsAnterior knee pain is a dull, aching pain that is most often felt:Behind the kneecap (patella)Below the kneecapOn the sides of the kneecapOne common symptom is a grating or grinding sensation when the knee is flexed (when the ankle is brought closer to the back of the thigh).Symptoms may be more noticeable with:Deep knee bendsGoing down stairsRunning downhillStanding up after sitting for awhile
Signs and testsThe health care provider will perform a physical examination. The knee may be tender and mildly swollen, and the kneecap may not be perfectly lined up with the thigh bone (femur).When you flex your knee, you may feel a grinding sensation below the kneecap. Pressing the kneecap when the knee is straightening out may be painful.X-rays are usually normal, although a special x-ray view of the kneecap may show signs of arthritis or tilting.MRI scans are rarely needed.
TreatmentResting the knee for a short period of time and taking nonsteroidal anti-inflammatory drugs (NSAIDs) such as ibuprofen, naproxen, or aspirin may help relieve pain. Other treatments or self-care for anterior knee pain include:Changing the way you exerciseLearning and performing exercises to both strengthen and stretch the quadriceps and hamstring musclesLosing weight (if you need to)Special shoe inserts and support devices (orthotics -- for people with flat feet)Taping to realign the kneecap Wearing the correct running or sports shoesSurgery for pain behind the kneecap (anterior knee pain) is rarely needed. During the surgery: Kneecap cartilage that has been damaged may be removed. Changes may be made to the tendons to help the kneecap move more evenly.
Expectations (prognosis)Anterior knee pain often improves with a change in activity, exercise therapy, and the use of NSAIDs.
Calling your health care providerCall for an appointment with your health care provider if you have symptoms of this disorder.
ReferencesCollado H, Fredericson M. Patellofemoral pain syndrome. Clin Sports Med. 2010;29:379-398.De Carlo M, Armstrong B. Rehabilitation of the knee following sports injury. Clin Sports Med. 2010;29:81-106.Steiner T, Parker RD. Patella: subluxation and dislocation. 2. Patellofemoral instability: recurrent dislocation of the patella. In: DeLee JC, Drez D Jr., Miller MD, eds. DeLee and Dree's Orthopaedic Sports Medicine. 3rd ed. Philadelphia, Pa: Saunders Elsevier;2009:chap 22:sect C.Silverstein JA, Moeller JL, Hutchinson MR. Common issues in orthopedics. In: Rakel RE, ed. Textbook of Family Medicine. 8th ed. Philadelphia, Pa: Saunders Elsevier; 2011:chap 30.