Knee bursitis or prepatellar bursitis is an inflammation of the bursa in the front of the kneecap (patella). It occurs when the bursa becomes irritated and produces too much fluid, which causes it to swell and put pressure on the adjacent parts of the knee.
Bursae are small, jelly-like sacs that are located throughout the body, including around the shoulder, elbow, hip, knee, and heel. They contain a small amount of fluid, and are positioned between bones and soft tissues, acting as cushions to help reduce friction.
Prepatellar bursitis is often caused by pressure from constant kneeling. Plumbers, roofers, carpet layers, coal miners, and gardeners are at greater risk for developing the condition.
A direct blow to the front of knee can also cause prepatellar bursitis. Athletes who participate in sports in which direct blows or falls on the knee are common, such as football, wrestling, or basketball, are at greater risk for the condition.
Other people who are more susceptible to the condition include those with rheumatoid arthritis or gout.
Prepatellar bursitis can also be caused by a bacterial infection. If a knee injury breaks the skin, such as an insect bite, scrape, or puncture wound, bacteria may get inside the bursa sac and cause an infection.
- Pain with activity, but not usually at night
- Rapid swelling on the front of kneecap
- Tenderness and warmth to the touch
- Bursitis caused by infection may produce fluid and redness
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 any recent knee injury. They may also ask 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 the bursa. This is a straightforward procedure. The skin on the front of your knee is sterilised 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 kneecap. 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 antibiotic medicines will treat it.
You do not usually need any X-rays or scans to diagnose housemaid’s knee unless your doctor is unsure about the diagnosis.
What are the treatment options?
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 (eg, flucloxacillin with phenoxymethylpenicillin (penicillin V), or co-amoxiclav). Usually, these antibiotics can be taken by mouth. If the infection is severe, your doctor may suggest that you be 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 be 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 cut (incision) should be 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 medicines or surgery.
- 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.
Non-steroidal anti-inflammatory drugs (NSAIDs), 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 medicine 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. You are unlikely to get complications after this procedure. However, occasionally the inflammation of the bursa (bursitis) can come back, or you can get infection, bleeding or damage to the tendon joined to the kneecap.
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 outlook (prognosis)?
Generally, the outcome is very good with appropriate treatment. You should find the condition clearing up in a few weeks.
However, if housemaid’s knee is persistent (chronic) or keeps coming back you might get long-term pain and have problems moving your knee.
You should take care if you have a job or hobby that involves kneeling for a long time or frequently. In such cases, you should use thick foam cushions, or knee pads. Knee pads should especially be used by people who have already had an episode of housemaid’s knee, in order to prevent it from coming back.