What is knee bursitis?
A bursa is a closed, fluid-filled sac that functions as a gliding surface to reduce friction between tissues of the body. Bursae is plural for bursa. The major bursae are located adjacent to the tendons near the large joints, such as the shoulders, elbows, hips, and knees.
When a bursa becomes inflamed, the condition is known as bursitis. This can cause swelling, warmth, and tenderness in the affected area. Most commonly, bursitis is caused by local soft-tissue trauma or strain injury, and there is no infection (aseptic bursitis).
On rare occasions, particularly when the immune system is suppressed, the bursa can become infected with bacteria. This condition is called septic bursitis.
The knee joint is surrounded by three major bursae. At the tip of the knee, over the kneecap bone (patella), is the prepatellar bursa. This bursa can become inflamed (prepatellar bursitis) from direct trauma to the front of the knee. This commonly occurs when maintaining a prolonged kneeling position, thereby causing irritation of the prepatellar area. It has been referred to as "housemaid's knee," "roofer's knee," and "carpet layer's knee," based on the patient's associated occupational histories.
The strain of the large tendon below the kneecap can cause both tendonitis and infrapatellar bursitis. This bursa of the knee is located just under the kneecap beneath the large tendon that attaches the muscles in front of the thigh and the kneecap to the prominent bone in front of the lower leg. This bursa is called the infrapatellar bursa, and when inflamed, the condition is called infrapatellar bursitis. It is commonly seen with inflammation of the adjacent tendon as a result of a jumping injury, hence the name "jumper's knee."
Inflammation of the bursa at the inner side of the knee (anserine area) can cause pes anserine bursitis. Pes anserine bursitis causes local tenderness of the inner knee.
This bursa of the knee is located on the lower inner side of the knee and is called the "anserine bursa." This bursa most commonly becomes inflamed in middle-aged women. This condition is referred to as anserine bursitis. Anserine bursitis is particularly common in those who are obese. These patients can notice pain in the inner knee while climbing or descending stairs.
A second bursa of the knee is located just under the kneecap beneath the large tendon that attaches the muscles in front of the thigh and the kneecap to the prominent bone in front of the lower leg. This bursa is called the infrapatellar bursa, and when inflamed, the condition is called infrapatellar bursitis. It is commonly seen with inflammation of the adjacent tendon as a result of a jumping injury, hence the name "jumper's knee." This condition is generally treated with ice, rest, and oral anti-inflammatory and/or pain medicines.
A third bursa of the knee is called the "anserine bursa." It is located on the lower inner side of the knee. This bursa most commonly becomes inflamed in middle-aged women. This condition is referred to as anserine bursitis. Anserine bursitis is particularly common in those who are obese. These patients can notice pain in the inner knee while climbing or descending stairs. Anserine bursitis is generally treated with ice, rest, and oral anti-inflammatory and/or pain medicines, although cortisone injections are also given.
What causes knee bursitis?
Bursitis of the knee can occur when the bursa fills with blood from injury and overuse, such as from athletic competition. Bursitis can also occur from rheumatoid arthritis and from deposits of crystals, as seen in patients with gouty arthritis and pseudogout.
The prepatellar bursa can also become infected with bacteria (septic bursitis). When this happens, fever may be present. This type of infection usually occurs from breaks in the overlying skin or puncture wounds. The bacterium involved in septic bursitis of the knee is usually Staphylococcus, which is normally present on the skin. Rarely, a chronically inflamed bursa can become infected by bacteria spreading through the blood.
What are the symptoms of knee bursitis?
Bursitis can lead to varying degrees of swelling, warmth, tenderness, and redness in the overlying area of the knee.
As compared with knee joint inflammation (arthritis), it is usually only mildly painful. It is frequently associated with increased pain when kneeling and can cause stiffness and pain with walking. Also, in contrast to problems within the knee joint, the range of motion of the knee is frequently preserved and the swelling is outside of the joint.
Diagnosis of knee bursitis
Bursitis of the knee is diagnosed based on the typical location of a bursa displaying signs of inflammation including
- knee pain,
- stiffness, and
- sometimes redness and warmth.
Typically, there is point tenderness at the site of the inflamed bursa.
IMAGESSee an illustration of the knee joint plus our entire medical gallery of human anatomy and physiology See Images
What is the treatment for knee bursitis?
The treatment of any bursitis depends on whether or not it involves infection. Non-infectious (aseptic) prepatellar bursitis can be treated with ice compresses, rest, and anti-inflammatory and pain medications.
When ice packs and anti-inflammatory drugs are not effective, knee bursitis can require aspiration of the bursa fluid and/or a local cortisone injection. This procedure involves the removal of the fluid with a needle and syringe under sterile conditions and can be performed in the doctor's office. Sometimes the fluid is sent to the laboratory for further analysis. Noninfectious knee bursitis can also be treated with an injection of cortisone medication into the swollen bursa. Cortisone injections are sometimes done at the same time as the aspiration procedure.
Septic bursitis requires even further evaluation and treatment. The bursal fluid can be examined in the laboratory to identify the microbes causing the infection.
- It requires antibiotic therapy, often intravenously.
- Repeated aspiration of the inflamed fluid may be required.
- Surgical drainage and
- removal of the infected bursa sac (bursectomy) may also be necessary.
What is the prognosis for knee bursitis?
The outlook for knee bursitis is generally very good. Mild bursitis resolves spontaneously with rest. More significant bursitis can require medications (either taken by mouth or locally injected) to reduce inflammation. Infectious bursitis requires drainage, possibly surgical resection, and antibiotics.
Top Knee Bursitis Related Articles
FeverAlthough a fever technically is any body temperature above the normal of 98.6 F (37 C), in practice, a person is usually not considered to have a significant fever until the temperature is above 100.4 F (38 C). Fever is part of the body's own disease-fighting arsenal; rising body temperatures apparently are capable of killing off many disease-producing organisms.
BursitisBursitis is inflammation of a bursa. A bursa is a fluid-filled sac found in the joints that cushions them. Bursitis is an inflammation of the bursa, most commonly caused by repetitive motion. Bursitis can be caused by a bacterial infection and should be treated with antibiotics, ice, and rest.
Bursitis Symptoms and TreatmentsDiagnosed with bursitis? Learn about treatment and prevention for trochanteric bursitis, as well as hip, knee, shoulder and other bursitis types.
Cortisone InjectionCortisone injections are used to treat small areas of inflammation or widespread inflammation throughout the body. There is minimal pain from these injections, and relief from the pain of inflammation occurs rapidly.
GoutBuildup of uric acid crystals in a joint causes gouty arthritis. Symptoms and signs include joint pain, swelling, heat, and redness, typically of a single joint. Gout may be treated with diet and lifestyle changes, as well as medication.
Gout SlideshowGout attacks (gouty arthritis) are caused by crystals of uric acid deposits. Learn about symptoms, causes, treatments and medication for this painful condition.
Knee Injury and Meniscus TearsKnee injuries, especially meniscus tears, are common in contact sports. Symptoms and signs of a torn meniscus include knee pain, swelling, a popping sound, and difficulty bending the leg. Treatment may involve resting, icing, compressing, and elevating the knee, in addition to wearing a knee brace, taking anti-inflammatory medications, and stretching the knee.
Knee Joint PictureThe knee joint has three parts. See a picture of Knee Joint and learn more about the health topic.
Obesity and OverweightGet the facts on obesity and being overweight, including the health risks, causes, reviews of weight-loss diet plans, BMI chart, symptoms, causes, surgical and nonsurgical treatments, and medications.
Pain Management: All About Your KneesThey do their job so well that you might take them for granted. Learn how they're put together, what can go wrong with them, and what you can do about it when something does.
Knee Pain Dos and Don'tsYour knees go through a lot in the course of a day, and sometimes they can run into trouble. Here are a few things you can do when knee pain hits.
Rheumatoid Arthritis (RA)Rheumatoid arthritis (RA) is an autoimmune disease that causes chronic inflammation of the joints, the tissue around the joints, as well as other organs in the body.
Sprains and StrainsAn injury to a ligament is called a sprain, and an injury to muscle or tendon is called a strain. Sprains and strains may be caused by repetitive movements or a single stressful incident. Symptoms and signs include pain and swelling. Though treatment depends upon the extent and location of the injury, rest, ice, compression, and elevation are key elements of treatment.
What Can Cause Pain Behind the Knee?What causes pain behind the knee? Learn about Baker's cyst and other causes of pain behind the knee and what to do about them.
What Is Aspiration of the Olecranon Bursa?Apiration of the olecranon bursa is the drainage of fluid from the elbow joint via needle. The olecranon is the pointed bone tip of the elbow. A bursa is a fluid-filled sac at the joint that helps the skin glide over the bone. Normally, this sac has little fluid and lays flat; however, the bursa can become inflamed and fill with extra fluid, resulting in painful swelling at the tip of the elbow.