septic bursitis knee

septic bursitis knee


Our knee has 11 bursae. The bursae are small pillow-like sacs that facilitate the movement of our joints. The cells of the wall of these small sacs can become inflamed and infected after the entry of bacteria.

Infectious bursitis of the knee is one of the most well-known and common septic bursitis, which we want to talk about more.

What are bursae, what are the common causes and symptoms of their infection, and what are the main and definitive diagnoses and treatments for septic knee bursitis are among the topics we discuss in this article.


What is knee bursitis?

Risk factors

The mechanism of septic knee bursitis


What are the causes of knee bursitis?

Symptoms of knee bursitis

The differences

Diagnosis of septic bursitis of the knee

Septic bursitis of the knee and their causes


The final word



What is knee bursitis?

In our knees, in order to facilitate the movements between bones and tendons or the movements of tendons relative to each other, and their wear does not cause problems, pain and discomfort, small pillow-like sacs are installed between the worn surfaces, which are called bursae.

The wall of these sacs contains cells that produce a small amount of fluid called bursa fluid and accumulate inside the sac.

Among the duties of knee bursae, the following can be mentioned:

  • Reducing friction and pressure between bones
  • Eliminating wear of tendons with muscles and skin adjacent to the knee

The number of these bursae in each of our knees is 11. In other words, each of our knees has 11 well-known and distinct bursae, most of which are located in the inner (medial) part of the knee.

If we want to define knee bursitis in general, we must say that any factor that causes damage and pressure to the knee and bursa causes the irritation of the membrane cells inside these small pillow-like sacs, and their irritation causes inflammation of this layer.

Following inflammation, the jelly-like substance inside the bursa increases its secretion.

As a result, swelling, pain and increased irritability and discomfort will be caused in the knee joint due to this inflammation.

Bursitis is actually inflammation of the parietal layer of these sacs.

Not only the knee has a bursa, there are bursa in other joints, including the shoulder, elbow and other parts, and their function is to facilitate joint movements.


Risk factors

The factors that increase the probability of septic bursitis are:

  • Weight gain and obesity
  • age increasing
  • Performing repetitive movements
  • Diabetes
  • Chronic users of immunosuppressive drugs
  • Uncontrolled diabetes

Important note:

Immunodeficiency for various reasons, such as the use of immunosuppressive drugs, increases the probability of septic knee bursitis.


The mechanism of septic knee bursitis

When bacteria and other infectious microorganisms enter the bursa and multiply, for example, following trauma and the loss of the natural barrier of the skin on the knee, or injuries that cause cuts, scratches, and punctures in the skin near the superficial bursa, it makes the way for bacteria to directly enter the bursa and cause septic inflammation of the bursa.

It is said that in most cases, Staphylococcus aureus is the most common cause of septic bursitis. After Staphylococcus aureus, some types of Streptococcus also cause septic knee bursitis.

Also, soft tissue infections such as cellulitis can also cause secondary bursal infections.

Also, another way is the infection entering the bursa from other parts of the body, which, of course, is not a very common mechanism.

In cases of chronic septic bursitis, the patient should be immediately examined for systemic infections.

It is interesting to say that one of the other reasons that sometimes occurs is a patient who was referred due to non-septic bursitis of the knee and underwent aspiration and drainage of the knee joint fluid or joint injection of corticosteroids in order to relieve the symptoms of non-infectious bursitis and then developed septic bursitis.



It is said that one out of five cases of non-septic bursitis of the knee is an infectious one.

The prevalence of knee bursitis in men is about 0.6% on average and 0.2% in women.

The highest rate of prevalence in terms of occupation has been reported in the construction sectors and employees of the meat and food industry preparation department.

Many times, it is not easy to distinguish septic bursitis from non-septic bursitis due to the overlap of symptoms and the absence of severe pain or fever and chills in the patient's clinical symptoms.


What are the causes of knee bursitis?

In a short sentence, we can summarize that any factor that causes damage or infection of any of the bursa sacs can be associated with knee bursitis.

These reasons are as follows:

The most common cause of bursa damage and bursa inflammation is friction that irritates the cells of the bursa wall.

For this reason, it is more common in people who have special jobs that require kneeling on surfaces.

For example, mechanics or people who clean the ground, as well as plumbers and pipe openers, suffer from this problem more than others.

The reason for this is the chronic and continuous pressure and blows to the knee.

Another reason is acute trauma and cuts and open wounds on the knee, which can cause acute septic bursitis and the onset of symptoms can be very quickly.

Pay attention to the following summary as the most common and main causes of knee bursitis:

1. The first and most common reason is overuse or continuous overuse of the knee joint

2. The next reason is a strong and direct blow to the knee joint

3. The next cause is bacterial infections of the bursae

4. And the next cause is problems such as joint rheumatism, gout and also arthritis, which provides the basis for more occurrence of knee bursitis.


Symptoms of knee bursitis

The symptoms of knee bursitis vary in different people.

People can show different degrees of these symptoms:

The most common symptoms are:

  • A feeling of warmth and swelling
  • Local sensitivity or tenderness in the joint
  • Also reddening of the skin on the affected joint

The above were the most common symptoms of knee bursitis.

We have to add a few things to these symptoms:

If the cause of knee bursitis is infections, the affected person will experience more heat, redness and swelling in the injured knee area, and fever and chills may also occur.

Lethargy should be also added to the above symptoms.

In septic bursitis, that are very advanced and severe, the person has so much pain that he cannot put the affected foot on the ground.

As a general rule: the more the amount of fluid inside the bursa increases, the more inflammation there is, so this fluid increases and causes swelling.

This swelling is a lot, which can cause pain and problems in joint movement.

Also, the chemicals that are released during this infection and inflammation through the immune system can themselves cause increased pain and discomfort.

Another point that we should mention about the symptoms in the topic of bursitis is that the pain in non-septic knee bursitis is usually mild to moderate and usually the affected person has pain when he wants to make a certain movement with his knee and bend or straighten it.

At this time, his knee experiences more pain, discomfort or joint dryness.

But when septic bursitis develops, the person is in so much pain and discomfort that he feels this severe pain even while resting, and in more severe cases of septic bursitis, the pain is so great that the person cannot put the affected foot on the ground.


The differences

Non-septic bursitis of the knee is actually an inflammation that occurs in the cells of the inner wall of this sac.

When, for any reason, this inflammation is caused by an infectious agent, for example, bacteria entering the skin through open wounds, it is said that there is an septic bursitis.

Non-septic inflammatory bursitis is more common than septic bursitis in the knee.

In some articles it is said that one fifth of all bursitis and in other articles it is said that one third of all bursitis are infectious or septic bursitis.

That is, one out of five cases or one out of every three cases of knee bursitis is due to the inflammation of the bursa wall cells, bacteria and infectious agents.


Diagnosis of septic bursitis of the knee:

Your doctor will first take a complete medical history. He examines the symptoms, characteristics and clinical signs that exist in your knee.

In addition to the history, a proper knee examination helps the doctor to reach a diagnosis.

For accurate diagnosis, the doctor must do aspiration or drainage the fluid inside the swollen bursa and send it to the laboratory for culture and analysis.

A simple blood test such as CRP and ESR is very effective for counting blood cells and evaluating factors that indicate inflammation in the body.


Septic bursitis of the knee and their causes

Long-term kneeling and jobs such as plumbing and gardening, and people who put pressure on their knees for a long time, are more at risk of increasing inflammation and infection of the knee bursa.

Also, sports such as wrestling, volleyball and soccer increase the risk of knee bursitis.

We said that according to studies, one third of all bursitis cases are septic.

Obesity as well as arthritis and diabetes are factors that increase knee bursitis.

Bursitis that occurs in the medial part of the knee is known to be statistically most related to these disorders.

Among the infectious agents, bacteria are the main and most common cause of septic bursitis.

Among the bacteria, staph aureus, and after that some types of streptococcus are the most common cause of septic bursitis.



Non-septic bursitis is easily managed with conservative measures aimed at reducing inflammation.

For example, it is recommended that the person rest and limit the activities that aggravate the pain and use a cold compress and place the knees higher than the ground level to reduce the swelling and use common anti-inflammatory drugs such as naproxen, ibuprofen and celecoxib.

So, in order:

  1. Taking a proper history from the patient:

Because the patient may refer to occupational injuries, sports injuries, or recent injuries to the knee; as well as evaluating the symptoms that the patient says.

  1. Then physical examination of the knee:

In which the doctor evaluates the degree of swelling, consistency, softness and stiffness of the tissue under the arm, and evaluates the range of motion and pain of the adjacent joint, as well as the characteristics of the soft tissue and skin around the joint, as well as the swelling glands around the knee.

In addition to the tests mentioned above, to rule out diseases such as rheumatoid, gout, and other related cases, the doctor may perform additional tests on the bursal fluid that he has drained or blood tests of the patient.

MRI is usually not needed in bursitis unless the patient is suspected of having a bone or joint infection.

Or in cases where there is a need for surgery; in these three cases, the doctor also requests an MRI of the knee.

The cases where surgical treatment is performed include:

  • Cases of very severe septic bursitis that caused severe joint infections that did not respond to drug treatment with antibiotics.
  • Cases of chronic septic bursitis in people with underlying knee joint disease

Most of the non-septic bursitis are easily controlled and eliminated with normal measures.

But let's remember that the issue in septic bursitis is completely different.

For these bursitis, in addition to non-steroidal anti-inflammatory drugs that were recommended to control pain and inflammation, the use of antibiotics becomes part of the main treatment.

In mild cases, oral antibiotics should be continued for 10 days.

In severe septic bursitis and severe symptoms, repeating and continuing antibiotics will be required until the fluid inside the bursa is cleared of infectious symptoms.

It is important that patients who are immunocompromised and develop septic knee bursitis, or patients who have joint problems, should be hospitalized and treated with intravenous antibiotics.


The final word

septic bursitis of the knee occurs when an infectious agent, which is usually bacteria and is commonly 80 to 90% Staphylococcus aureus, causes inflammation of the wall cells that make up the knee bursae.

If the bursae of the knee become infected, they will commonly occur in superficial bursae that are located under the skin.

The most common bursa that gets infected in the knee is the bursa that is located on the patella and is called the prepatellar bursa.

Among the non-surgical interventions that the attending physician performs for the treatment of septic bursitis, the following can be mentioned:

aspiration of the fluid inside the bursa, intravenous injection of antibiotics, emptying the bursa by incision if aspiration is not possible due to the location of the infected bursa; And in cases that the patient does not respond to any of the above, open surgery is performed.

Severe knee pains with sensitivity to local touch, swelling, warmth, and redness that may or may not be accompanied by fever and in cases where there are underlying problems such as arthritis, limitation of knee joint movement is the main symptom.

Unlike normal bursitis, septic bursitis requires prompt treatment and diagnosis.

If you encounter any of the mentioned symptoms, be sure to immediately visit a reputable center equipped with orthopedic equipment so that the treatment can be done more easily and successfully in the early stages.

You may recover with just a course of antibiotic therapy along with anti-inflammatory drugs and rest.

In more severe cases, it may be necessary to drain the joint fluid several times and continue to take oral antibiotics, and even in cases where there is diabetes or immunodeficiency, you may need to be hospitalized and receive intravenous antibiotics, and in chronic and recurring cases, you may be a candidate for surgery.

Latest articles


submandibular gland swollen and painful

Have you ever heard the term sialadenitis? If you have recently noticed swelling of the submandibular glands, if you are looking for possible causes of swelling of the submandibular glands, read the following. Salivary gland swelling is called sialadenitis by doctors. Salivary gland secretions are necessary to moisten the mouth and throat and start digesting food.


sudden feeling of passing out anxiety

If you have experienced sudden stress and anxiety, if you want to know the causes of sudden filling out passing anxiety, Read more Often dizziness is associated with anxiety under the following headings Wooziness Light headedness


how get smell back after covid

How to restore a disturbed sense of smell following Covid19? Is there a way to speed up the olfactory recovery following Covid19? What are the ways to restore the sense of smell following Covid19? If you are one of those people who suffer from a sense of smell following a new coronavirus infection and are looking for a way to restore your sense of smell, read on.


Signs of a blood clotting disorder

If you want to know what signs and symptoms are associated with blood clots If you want to get acquainted with the signs and symptoms of blood clots. Read more What is a blood clot? What are the symptoms of a blood clot? What are the risks of a blood clot? What are the possible side effects of blood clots in the body? Why do blood clots form? Blood clots can be a sign and a symptom of what disorder and disease.


Sharp pulling pain in belly button

If you have sharp pain around the umbilicus (pre-umbilical). Read more. What causes sharp and pulling-like pain around the belly button?

share this content in :
Address: 393 University Avenue,Suite 200,Toronto ON MG5 2M2,CANADA

Phone: +1(647)303 0740

All Rights Reserved © By MarsoClinic

Terms of Use

Our company

Advisory board
Advisory board

Our products

Your Healthy Gut
Food intolerance
View All


Your Healthy Gut
Food intolerance
View All


Your Healthy Gut
Food intolerance
View All
logo-1 logo-2 logo-3 logo-foot  logo-4 logo-5 logo-6

Address: 393 University Avenue,Suite 200,Toronto ON MG5 2M2,CANADA


Phone: +1(647)303 0740

All Rights Reserved © By MarsoClinic

Terms of Use