Diagnosis

Your physician will take your history and physical exam, which will aid in making the proper diagnosis. Tenderness and swelling of the kneecap and, in some cases, the presence of lumps inside your knee, confirm the diagnosis.

If your symptoms started after a fall, your doctor may order an X-ray film to make sure your kneecap isn't fractured. If an infection is suspected, the doctor may drain the fluid and send it to the lab to determine if bacteria are present.