Knee bursitis is the inflammation of the bursa, a small, fluid-filled sac, near the knee joint. The bursal tissue is a protective tissue that sits between the bone and the skin, reducing friction between tissues of the body. Major bursae are located by the tendons near large joints, such as the hips, shoulders, elbows and knees.
There are three major bursae surrounding the knee joint: the prepatellar bursa, the infrapatellar bursa and the anserine bursa. The prepatellar bursa is located over the kneecap bone — and the most common form of knee bursitis is prepatellar bursitis, which is an inflammation of this bursa. The other two major bursae can also become inflamed, but infrapatellar bursitis and anserine bursitis are less common.
What are the symptoms of knee bursitis?
While knee bursitis symptoms can vary depending on which area of the knee is affected, knee bursitis is generally only mildly painful. However, if the bursae are more severely swollen, then patients may experience greater pain, especially if there is sudden pressure or the bursae gets squeezed. The pain from knee bursitis can last for a few weeks — however, this again depends on the extent of inflammation.
Other symptoms include:
- Warmth: The temperature might be greater in the affected area on the knee.
- Redness: The knee might be pink or red.
- Stiffness when walking: In more severe cases, the swollen bursa can make it hard to straighten or flex the knee, causing stiffness and reduced range of motion.
- Fever and illness: These symptoms only occur in cases of septic bursitis, which is a serious condition that requires immediate medical care.
In addition to these symptoms, swelling can cause a lump the size of a grapefruit to appear on the knee under the skin.
What causes knee bursitis?
Knee bursitis, especially prepatellar bursitis, is typically caused by applying undue pressure on the knee, such as repeated kneeling. According to an article published in American Family Physician, coal miners, carpet layers, housemaids, plumbers, concrete finishers, and roofers are all occupations that make one susceptible to prepatellar bursitis. This is due to the chronic microtrauma that results from repetitive friction on the tissue overlying the bursa.
Other risk factors for knee bursitis include:
- Weight: Both prepatellar bursitis and anserine bursitis can occur in people who are obese. Generally, being overweight puts added pressure on the knees, which is one of the main causes of knee bursitis.
- Sports: Bursitis can occur in athletic competition if the bursa fills with blood due to injury and overuse.
- Existing conditions: Knee osteoarthritis, rheumatoid arthritis, gout and pseudogout can increase the likelihood of bursitis.
- Prior injury: If the knee has experienced any trauma, then the damage to the prepatellar bursa can remain inflamed, causing knee bursitis symptoms.
In addition, infection can cause septic bursitis, which is less common and occurs when the bursa is infected. This condition, which is more serious and requires urgent treatment, occurs more frequently in the summer months, and can happen when a cut, puncture, insect bite or scrape breaks the skin, allowing bacteria to enter the bursa sac and cause an infection. People who have immunodeficiency are more susceptible to septic bursitis, including people with cancer, lupus, diabetes and HIV/AIDS.
How is knee bursitis diagnosed?
Your doctor will typically examine the knee and look for the symptoms listed above, including swelling, tenderness, pain, warmth, redness and stiffness. They will also ask about the onset of these symptoms and other conditions you have to rule out other potential knee problems. To determine whether or not it is bursitis caused by an infection, they will ask if you have experienced any fever or chills, as septic bursitis requires different treatment than regular knee bursitis.
The patient interview and physical examination is typically all that’s needed to diagnose knee bursitis. However, the doctor may draw fluid from the bursa if they are concerned about the possibility of infection or other underlying issue. They may examine the sample’s white blood cell count and glucose levels to see if there are abnormal levels that indicate there is an infection. The Gram stain test can also indicate if troublesome bacteria are present in the sample, indicating potential infection.
Imaging tests, such as X-rays and MRIs, are typically not performed in diagnosing knee bursitis unless your doctor suspects there is a soft tissue injury or fracture causing your symptoms.
What is the treatment for knee bursitis?
According to Dr. Vladimir Alexander, Founding Partner of Alexander Orthopaedics, knee bursitis is initially treated by avoiding pressure. “No kneeling, no tight pants, no bracing, no direct pressure, no massage, no manipulation — just avoid pressure and irritation to the area.”
This also means no rubbing, even though patients may be tempted.
“People will frequently say that it feels good when they rub it, but when they rub it, they irritate the bursa, and the bursa becomes more irritated and swollen, so that’s exactly the opposite of what you want to do.”
Using knee pads while kneeling and remembering to stretch before exercising also helps reduce the strain on your knees. Also, limit exercise to low-impact workouts, such as a light walk or stationary bike ride.
The popular RICE (rest, ice, compression, elevation) method applies here. Resting can help take pressure off of your knee, and ice can help get the swelling down. Using a compression wrap and elevating the affected leg when possible also helps. In fact, mild cases of bursitis usually resolve themselves with some activity modification and rest.
Anti-inflammatory medication, such as aspirin and ibuprofen, can be used as well to help ease the symptoms. Topical medications, such as creams, gels, patches and sprays, can also help provide pain relief.
Aspiration and injections
Another treatment is removing fluid from the swollen bursa using a needle and syringe. However, Dr. Alexander says it is not preferred.
“When fluid is stagnant in the body and doesn't move, there’s a very high chance of inoculating it with the bacteria, and so drawing fluid off and injecting will frequently cause that area to become infected, and if it becomes an infective bursitis, that frequently requires surgery to be removed. So, we try not to ask to draw fluid off or inject with cortisone because it can cause more problems than good.”
Surgical treatment is typically not required for knee bursitis. However, according to American Family Physician, surgery may be required for persistent or recurrent bursitis cases, or in cases where the enlargement of the bursa interferes with function. In addition, septic bursitis may require surgery if antibiotics are not effective.
What is the knee bursitis recovery process?
The pain caused by knee bursitis can range from inconvenient at best to severe at worst. If you’re experiencing pain in your knee that’s disrupting your everyday life, we’re here to help you recover faster. We have a variety of individualized knee surgery and treatment options that provide holistic, patient-centered care.