Knee Bursitis

Definition

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 between moving parts in your knee — bone and skin, bone and muscle, bone and tendons, or tendons and muscles.

If you have knee bursitis, one or more of the 11 bursae associated with each of your knees may be inflamed. 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.

 

Symptoms

In most cases, knee bursitis begins gradually, and it may worsen over time if left untreated. If you have knee bursitis, 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 your knee

Your doctor may use one of the following terms to describe your condition and indicate the location of the inflamed bursa:

  • Prepatellar bursitis, or kneecap bursitis, affects the bursa that lies in front of your kneecap (patella), between the patella and your skin. Kneecap bursitis, one of the most common forms of the disorder, may be referred to as housemaid’s knee or carpet layer’s knee because it affects people who frequently work on their hands and knees.
  • Pes anserine bursitis is inflammation of a bursa that lies at the inner lower part of the knee, between your shinbone (tibia) and three tendons connected to the hamstring muscles on the inside of your leg. This type of knee bursitis, also more common than others, is sometimes called goosefoot bursitis because the three tendons somewhat resemble the shape of a goosefoot.
  • Infrapatellar superficial bursitis affects the bursa that lies below your kneecap, between your skin and the tendon that connects the kneecap and tibia. This type of bursitis, associated with frequent kneeling, is sometimes called preacher’s knee.
  • Medial collateral ligament bursitis affects a bursa between the tibia and a ligament on the inner side of your knee that connects the tibia and thighbone (femur). Inflammation of this bursa usually results from a twisting injury to your knee.

Inflammation may affect other bursae in your knee, but these forms of knee bursitis are less common.

Causes

Frequent and sustained pressure on the affected bursa most often causes knee bursitis.

Other causes of knee bursitis include:

  • A severe blow to your knee directly causing inflammation of a bursa
  • A severe blow causing internal bleeding into a bursa that subsequently induces inflammation (hemorrhagic bursitis)
  • Frequent falls on your knee
  • Bacterial infection of the bursa (infectious or septic bursitis)
  • Complications from osteoarthritis, rheumatoid arthritis or gout in your knee

Risk factors

An activity or condition that puts chronic strain or pressure on bursae significantly increases your risk of knee bursitis.

Prepatellar and infrapatellar superficial bursitis
People who work on their knees for long periods of time — carpet layers, plumbers and gardeners — are at increased risk of prepatellar bursitis and infrapatellar superficial bursitis.

Prepatellar bursitis is also associated with sports that result in direct blows or frequent falls on the knee, such as wrestling, football and volleyball.

Pes anserine bursitis
Common risk factors for pes anserine bursitis include abnormal gait, obesity and osteoarthritis. Poor sports training, inadequate stretching and tight hamstrings — especially for swimmers and runners — also increase the risk of pes anserine bursitis.

Infectious bursitis
People who have medical conditions or who take medications that make them more susceptible to infection may have a greater risk of infectious knee bursitis. These conditions include cancer, diabetes, lupus, alcoholism and HIV/AIDS.

When to seek medical advice

A number of injuries and conditions in addition to bursitis can cause pain in your knees. It’s important, therefore, to get an accurate diagnosis and appropriate treatment. Call your doctor when:

  • Pain is severe or worrisome
  • You can’t bear weight on a knee
  • You’ve experienced a traumatic blow to your knee
  • Your knee is swollen
  • You have a fever in addition to pain and swelling in your knee — a possible indication of infection

If you’re experiencing pain in your knee for the first time and the pain isn’t severe or disabling, you can try treating it yourself. This includes resting, icing and elevating the affected knee. To reduce pain and inflammation, you may also take nonsteroidal anti-inflammatory drugs, such as ibuprofen (Advil, Motrin, others) or an analgesic pain reliever such as acetaminophen (Tylenol, others). If you don’t notice any improvement in three to seven days, see your doctor.

Tests and diagnosis

Your doctor will conduct an examination to determine the cause of knee pain. He or she may begin with questions that can help make a diagnosis of bursitis or another disorder:

  • When did your pain begin?
  • Did it begin suddenly or gradually?
  • What kind of work or recreational activities do you do that may affect your knees?
  • Does your pain occur or worsen when doing certain activities, such as kneeling or climbing stairs?
  • Have you recently fallen, been in an accident or suffered a blow to your knee?
  • What kind of treatments have you tried at home?
  • What effect did those treatments have?

Your doctor will inspect your knee by:

  • Comparing the condition of both knees, particularly if only one is painful
  • Gently pressing on different areas of your knee to detect warmth, swelling and the source of pain
  • Carefully moving your legs and knees into different positions to determine the range of motion in your knee joint and identify movement associated with pain

In most cases, your doctor can make a diagnosis of knee bursitis with this examination. However, he or she may order an X-ray or other imaging study of your knee to rule out an injury that can cause signs and symptoms similar to those of bursitis.

If the cause of bursitis isn’t apparent — such as excessive kneeling — or if there’s any sign of infection such as a fever or redness around the knee, he or she may use a needle to draw fluid from the knee joint. This procedure is called aspiration. The color of the fluid may itself provide clues to the condition, and your doctor will send the fluid out for a laboratory test.

Treatments and drugs

Your doctor will most likely prescribe a course of self-care to treat knee bursitis. However, if you don’t respond well to self-care treatments or the pain and inflammation are severe, he or she may recommend one of the following interventions:

  • 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. You may alleviate these side effects by applying an ice pack at the injection site and taking an anti-inflammatory drug as directed by your doctor.

Your doctor won’t give you a corticosteroid injection if you have hemorrhagic or infectious bursitis.

  • 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.

If you have hemorrhagic bursitis, your doctor will aspirate the bursa to remove blood.

  • Antibiotics. If an infection has caused the knee bursitis, your doctor will prescribe a course of antibiotic treatment.
  • 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.
  • Surgery. On rare occasions — if you have severe chronic bursitis and don’t respond to other treatments — your doctor may recommend a bursectomy, or surgical removal of a bursa.

Prevention

You can take a number of steps to avoid knee bursitis or prevent its recurrence:

  • Wear kneepads when you’re working on your knees or participating in sports that put your knees at risk.
  • Rest your knees and stretch your legs as much as possible if you work on your knees for extended periods.
  • Stretch your legs before and after a workout.
  • Vary your exercise routine to give your knees a rest.
  • Elevate and ice your knees for about 20 minutes after a workout or after working on your knees for a long time.