Your 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 thigh.
• You are doing too much activity that places extra stress on the kneecap (such as running, jumping or twisting, skiing, or playing soccer).
• Your muscles are not balanced and your core muscles maybe weaker.
• The groove in the thighbone where the kneecap normally rests is too shallow.
• You have flat feet.

Anterior knee pain is more common in:

• People who are overweight
• People who have had a dislocation, fracture, or other injury to the kneecap
• Runners, jumpers, skiers, bicyclists, and soccer players who exercise often
• Teenagers and healthy young adults, more often girls

Other possible causes of anterior knee pain include:

• Arthritis
• Pinching of the inner lining of the knee during movement (called synovial impingement or plica syndrome)