Patellofemoral pain syndrome is pain in the front of the knee. It may be caused by overuse, injury, excess weight, an improperly aligned kneecap, or changes under the kneecap.

Symptoms include:

• Pain, especially when sitting with bent knees, squatting, jumping, or using the stairs (especially going down stairs).
• Occasional knee buckling, where the knee suddenly and unexpectedly gives way and does not support body weight.
• A catching, popping, or grinding sensation with walking or moving the knee.

Patellofemoral pain syndrome most commonly occurs in teenagers, manual laborers, and athletes. It can be relieved by avoiding activities that make symptoms worse, such as sitting, kneeling, or doing exercises in the bent-knee position.

Patellofemoral pain syndrome can be relieved by taking nonprescription anti-inflammatory drugs (NSAIDs), and by resting and icing the knee. You can also try heat to see if it helps. Physical therapy can help increase flexibility and balance the strength in the leg muscles. Taping the knee or using a brace may stabilize the kneecap. Surgery may be needed if pain does not go away.