Housemaid's Knee (Prepatellar Bursitis)

What is bursitis?

Bursitis means inflammation within a bursa. A bursa is a small sac of fluid with a thin lining. There are a number of bursae in the body. Bursae are normally found around joints and in places where ligaments and tendons pass over bones. They can also be found in other places if there has been unusual pressure or friction placed on that area.

Generally, the function of a bursa is to help reduce friction and allow maximal range of motion around joints. When there is inflammation within a bursa (bursitis), the bursa swells due to an increase in the amount of fluid within the bursa sac.

What is housemaid's knee?

There are four bursae located around the knee joint. They are all prone to inflammation, or bursitis, but the prepatellar bursa (the bursa in between the skin and the knee cap) is most commonly affected. Its position is shown in the diagram. Housemaid's knee is the name given to inflammation of the prepatellar bursa.

What causes housemaid's knee?

There are a number of different things that can cause housemaid's knee:

A sudden, one-off, injury to the knee
For example a fall or direct blow onto the knee.

Recurrent minor injury to the knee
This usually happens after spending long periods of time kneeling down, putting pressure on the patella (knee cap). Historically, this was typical of housemaids who spent long periods of time scrubbing floors on their knees, hence the term housemaid's knee.

Infection
The fluid in the prepatellar bursa sac can become infected and cause bursitis. This is particularly common in children with housemaid's knee. This usually follows a cut, scratch or injury to the skin on the surface of the knee. This injury allows bacteria (germs) to spread infection into the bursa.

Another inflammatory disease
If you already have an inflammatory disease such as rheumatoid arthritis, you are more likely to suffer from bursitis. Rheumatoid arthritis is a form of arthritis that causes inflammation, pain and swelling of joints.

Gout
If you have gout, you are more likely to get bursitis. Gout is caused by a build-up of uric acid crystals. Uric acid is a chemical in the blood that is usually harmless and passed out with the urine. In gout, it builds up and collects within a joint, causing pain, inflammation and joint swelling.

Who gets housemaid's knee?

Any age group can be affected by housemaid's knee. It is generally more common in males than in females. Housemaid's knee in children is more likely to be caused by infection. Infection is also a common cause of housemaid's knee in people whose immune system is not working normally. Such people include those receiving steroid treatment or those on chemotherapy treatment for cancer.

Housemaid's knee is more common in tradesmen who spend long periods of time kneeling, for example, carpet fitters, concrete finishers and roofers.

What are the symptoms of housemaid's knee?

Housemaid's knee causes pain and swelling of the affected knee. You may notice redness of the skin over the knee and your knee cap may be tender to touch. You may also have difficulty bending your knee and difficulty kneeling and walking. If housemaid's knee is caused by infection, you may have a fever (temperature).

How is housemaid's knee diagnosed?

Your doctor is usually able to diagnose housemaid's knee simply by examining your knee. They may ask you questions about your occupation or if you have had an recent knee injury. They may also ask about any drug that you are taking and whether you have any history of other joint problems.

If your doctor suspects that housemaid's knee is caused by infection, they may suggest that they draw some fluid from your knee. This is a straightforward procedure. The skin on the front of your knee is sterilized with some fluid and the procedure is carried out in a clean environment. A small needle is used to take a sample of the fluid from your prepatellar bursa, which is directly underneath the skin in front of your knee-cap. This fluid is sent off to the laboratory to look for signs of infection. If infection is confirmed, the laboratory may be able to suggest which antibiotics will treat it.

You do not need any X-rays or scans to diagnose housemaid's knee.

What are the treatment options for housemaid's knee?

The treatment options for housemaid's knee depend on whether or not it is caused by infection.

Housemaid's knee caused by infection
If your doctor suspects that your housemaid's knee is caused by infection, they may draw some fluid from your knee, as described above. They can send this fluid off to the laboratory for tests. Whilst waiting for the results, they may prescribe some antibiotics for you to take. Usually, these antibiotics can be taken by mouth. If the infection is severe, your doctor may suggest that you are admitted to hospital and given intravenous antibiotics (antibiotics into your veins).

When the doctor gets the results back from the laboratory after a couple of days, they may suggest that your antibiotics are changed. They should now know the antibiotic that is most likely to be effective in treating the infection.

If your symptoms do not seem to be improving despite 36-48 hours of antibiotics, your doctor may suggest that a small incision is made on the front of your knee to allow the infected fluid to drain out from the bursa. This may require referral to hospital but does not normally mean an overnight stay.

Housemaid's knee due to other causes
Most episodes of housemaid's knee will settle with supportive treatment and do not require drugs or surgery.

• Supportive treatment
  • Resting the knee.
  • The use of ice packs on the knee (a tea towel wrapped around a bag of frozen peas makes a good ice pack).
  • The use of a thick foam cushion, or knee pads, to kneel on can help to prevent recurrence.
  • A physiotherapist can help by teaching you some exercises if your knee joint is affected by a reduced range of movement.
  • A stick or a cane can help with walking.
• Drug treatment
  Non-steroidal anti-inflammatory drugs, such as ibuprofen, can be taken for mild to moderate pain caused by housemaid's knee. They also help to reduce inflammation.
  
  If housemaid's knee becomes more troublesome, your doctor may suggest that they draw out the fluid from the bursa using a small needle. They can then inject a steroid drug into the bursa to counteract the inflammation. The idea is that the fluid will no longer accumulate. Infection must be excluded beforehand as the steroid injection can make any pre-existing infection worse. Complications following this procedure are uncommon but include recurrence of the bursitis, infection, bleeding and damage to the tendon joined to the knee-cap.
  
  
• Surgical treatment
  In rare cases when housemaid's knee does not go away, or keeps recurring, and is causing intolerable symptoms, surgery may be necessary.
  
  This is most commonly carried out using keyhole surgery. A local anaesthetic is used (an injection is given around the knee joint to numb the area and you are not put to sleep). It is usually done as a day-case which means that you are not admitted to hospital overnight. During the surgery the prepatellar bursa is removed. The knee joint can function perfectly well without this bursa and there are not usually any long term effects to the knee.

What is the prognosis (outcome) of housemaid's knee?

Generally, the prognosis of housemaid's knee is very good with appropriate treatment. An episode tends to resolve within a few weeks. However, if housemaid's knee is chronic (persistent) or recurrent then it can lead to chronic pain and reduced movement of the knee joint. Housemaid's knee caused by infection does need to be recognised quickly and treated promptly with antibiotics to avoid any long term problems.

Can housemaid's knee be prevented?

Care should be taken by people whose occupation, or hobby, involves prolonged and repetitive kneeling. Thick foam cushions, or knee pads, should be used in such cases to prevent the development of housemaid's knee. Knee pads should especially be used by people who have already had an episode of housemaid's knee to prevent recurrence.