Knee bursitis is inflammation of a bursa located near your knee joint. A bursa is a small fluid-filled, pad-like sac that reduces friction and cushions pressure points between your bones and the tendons and muscles near your joints.
Each of your knees has 11 bursae. While any of these bursae can become inflamed, knee bursitis most commonly occurs over the kneecap or on the inner side of your knee below the joint.
Knee bursitis causes pain and can limit your mobility. Treatment for knee bursitis often includes a combination of self-care practices and doctor-administered treatments to alleviate pain and inflammation.
Knee bursitis signs and symptoms may vary, depending on which bursa is affected and what precisely is causing the inflammation. In general, the affected portion of your knee may:
- Feel warm to your touch
- Appear swollen or feel squishy to your touch
- Be painful or tender when you move or put pressure on it
A sharp blow to the knee can cause symptoms to appear rapidly. But most cases of knee bursitis result from repetitive injuries — sustained in jobs that require a lot of kneeling — so symptoms usually begin gradually and may worsen over time.
When to see a doctor
The bursa that lies over your kneecap can sometimes become infected. Call your doctor if you have a fever in addition to pain and swelling in your knee.
Knee bursitis can be caused by:
- Frequent and sustained pressure, such as from kneeling
- A direct blow to your knee
- Frequent falls on your knee
- Bacterial infection of the bursa
- Complications from osteoarthritis, rheumatoid arthritis or gout in your knee
Knee bursitis is a common complaint, but the following factors may increase your risk of developing this painful disorder.
- Excessive kneeling. People who work on their knees for long periods of time — carpet layers, plumbers and gardeners — are at increased risk of knee bursitis.
- Participation in certain sports. Sports that result in direct blows or frequent falls on the knee — such as wrestling, football and volleyball — may increase your risk of knee bursitis. Runners may develop pain and inflammation in the anserine bursa, located on the inner side of your knee below the joint.
- Obesity and osteoarthritis. Obese women with osteoarthritis often develop bursitis involving the inner side of the knee below the joint.
- Impaired immune system. People who have medical conditions or who take medications that make them more susceptible to infection may have a greater risk of infectious (septic) knee bursitis. These conditions include cancer, diabetes, lupus, alcoholism and HIV/AIDS.
Depending on which parts of your knee are affected, your doctor may recommend one or more treatment approaches.
Medications for treating knee bursitis may include:
- Corticosteroid injection. Your doctor can inject a corticosteroid drug directly into an affected bursa to reduce inflammation. The inflammation usually subsides rapidly, but you may experience pain and swelling from the injection for a couple of days.
- Antibiotics. If an infection has caused the knee bursitis, your doctor will prescribe a course of antibiotic treatment.
Possible therapies needed for knee bursitis treatment may include:
- Aspiration. Your doctor may aspirate a bursa to reduce excess fluid and treat inflammation. He or she will insert a needle directly into the affected bursa and draw fluid into the syringe. As with a corticosteroid injection, aspiration may cause short-term pain and swelling.
- Physical therapy. Your doctor may refer you to a physical therapist or specialist in sports medicine, who can help you learn appropriate exercises to improve flexibility and strengthen muscles. This therapy may alleviate pain and reduce your risk of recurring episodes of knee bursitis.
If you have severe chronic bursitis and don’t respond to other treatments, your doctor may recommend that the bursa be removed surgically.