A bursa [BER-sah] is a small fluid-filled sac that cushions your tendons, bones, and ligaments as they move against each other. Bursitis [ber-SAHY-tis] is when a bursa becomes irritated or inflamed. This usually happens with injury or joint overuse.
Repetitive motion, such as running or joint stress, such as kneeling on a hard floor, can cause or worsen knee bursitis.
Knee bursitis most often occurs in the bursa over the kneecap or on the inner side of the knee, below the joint.
Knee bursitis can be very painful. Other common symptoms include:
- Pain with pressure (it hurts more when you press on it)
- Discomfort while the knee is in use or at rest
The first sign of trouble with knee bursitis is pain. The bursa that is found over the kneecap can sometimes become infected. See your doctor as soon as possible if you have any of the following symptoms, in addition to pain and swelling in the knee:
- Sudden inability to move the knee
- Disabling pain in the knee
- Excessive redness, swelling, or puffiness
- A rash or bruising in the knee
- Sharp or shooting pains
- Pain while exercising, moving, or otherwise exerting the knee
Symptoms of knee bursitis usually begin slowly and get worse as time passes.
Knee bursitis happens when the bursa fills with extra fluid and becomes inflamed. This inflammation puts pressure on the nearby tissue and causes discomfort.
Knee bursitis can be caused by joint overuse (at work or during recreation), by injury, like a sharp blow to the knee, or when a joint is put under pressure for a long time.
Knee bursitis can also be caused by:
- Frequent stress or pressure, such as kneeling on a hard floor
- Bacterial infection
- Complications from arthritis
You are also more likely to get bursitis at an older age, or if your occupation or hobbies involve frequent repetitive motion.
To diagnose bursitis, your doctor will usually perform a physical exam and may take a sample of the fluid inside the bursa to make sure it is not infected. This is called aspiration [as-per-AY-shuhn].
Imaging tests may be recommended to confirm or rule out knee bursitis.
- X-ray uses radio waves to create pictures of your knee. It may reveal a problem with a bone or another medical condition.
- MRI (magnetic resonance imaging) uses magnets and radio waves to create a more detailed image of the tissues in your knee. It can show if the bursa is infected or if a problem with a tendon is the cause of your pain.
- Ultrasound uses sound waves to create images of the joint. It can show swelling or damage in the affected area.
Often, knee bursitis will get better all by itself as long as it is not caused by an infection. To treat your knee bursitis, you will need to rest the affected joint and protect it from any further harm. Most people feel better within a few weeks with proper treatment. However, you may still experience recurrent flare-ups of bursitis in the affected area.
Typical measures to relieve knee bursitis pain include:
- Resting the knee to avoid overuse
- Applying ice to help reduce the swelling (usually during first 48 hours after symptoms occur)
- Applying heat, such as a heating pad or warm bath
- Taking an over-the-counter pain medicine, such as naproxen, aspirin, or ibuprofen to relieve the pain and reduce inflammation.
- Cushioning and supporting the knee, especially while sleeping
If these measures do not help, your doctor may recommend:
- Therapy, such as exercises or physical therapy designed to help strengthen the knee and prevent recurrence
- Medicines, such as antibiotics if the inflammation is caused by an infection
- Assistive devices, such as a cane, brace, or walker, to temporarily alleviate the knee joint stress
- Injections, such as a corticosteroid [core-tih-co-STARE-oyd] drug to quickly relieve inflammation
- Surgery, to drain or remove a bursa, but only in rare cases
Although some types of bursitis cannot be prevented, there are certain things you can do to help reduce your risk of developing bursitis, including:
- Exercise. Exercise, including proper warm-ups and and stretching, help keep your muscles conditioned, which makes it less likely for bursitis to occur.
- Kneeling pads. If you know you will be kneeling for a long period of time, use some type of padding to reduce the pressure on your knees.
- Avoiding excessive squatting. Overuse of the knees, such as excessive bending or squatting, can increase the force and strain on your knee joints.
- Taking breaks. Make sure to alternate repetitive tasks with rest so that the joints do not become over-strained.
- Lifting properly. Bend your knees when you lift. Failing to do so puts extra stress on the bursae in your hips.
- Wheeling heavy loads. Avoid carrying heavy loads because carrying heavy loads puts stress on the bursae in your shoulders.
- Maintaining a healthy weight. Additional weight places more stress on the knees.