Knee bursitis (housemaid's knee): what helps, and when it's infected

What it isStrong evidence

Bursae are small, fluid-filled sacs that cushion places where skin, tendon and bone rub. The knee has several. The one most often affected sits between the kneecap and the skin (prepatellar bursitis, or housemaid's knee). A rarer one sits just below the kneecap, over the tendon (superficial infrapatellar bursitis, or clergyman's knee, said to come from kneeling more upright). Both sit under the skin, outside the knee joint.

There are four kinds: after a fall or blow, when the bursa can fill with blood; from repeated kneeling and friction, the commonest; with gout or rheumatoid arthritis; and infected (septic) bursitis, usually from germs getting in through a cut, scratch, graze or bite, or after a needle has been put into the bursa.

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Who gets itEmerging evidence

Kneeling is the usual cause: plumbers, roofers, carpet and floor layers, concrete finishers, miners and gardeners, and sports with falls on the knee, such as football, wrestling and basketball. In a US study, 20% of carpet layers reported bursitis against 6% of millwrights and bricklayers, who seldom kneel, and using a knee kicker to stretch carpet was the only significant predictor. On ultrasound, the bursa was thickened in 49% of carpet and floor layers against 7% of house painters. Floor layers spent 56% of their working time in knee-straining positions, and that kind of work went with bursitis on examination.

Knee and elbow bursitis together affect at least 10 in 100,000 people a year, 80% of them men aged 40 to 60. In the UK, bursitis or cellulitis at or about the knee from severe or prolonged pressure is a prescribed industrial disease (A6) for people who kneel a lot at work.

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How it's recognisedStrong evidence

A swelling on the front of the knee, usually soft and movable, tender and warm, sometimes red, with pain when kneeling or bending the knee. Some long-standing bursitis is barely painful. A GP examines it and asks about your work, injuries and other conditions.

The knee joint itself usually still bends, because the swelling sits in front of the kneecap rather than inside the joint. After a fall, an X-ray checks for a broken kneecap, and an ultrasound scan can help tell bursitis from a skin infection (cellulitis).

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Infected bursitisEmerging evidence

In reviews of knee and elbow bursitis together, about 1 in 3 cases was infected: a 2014 German literature review and the French Society for Rheumatology's 2023 recommendations both give this figure (we read their summaries, not the full papers). The germ is usually Staphylococcus aureus, in 80 to 85% of cases.

Signs that point to infection are a high temperature, skin over the bursa that is clearly warmer than over the other knee, and a cut or broken skin over it. Up to half of infected cases are in people with diabetes or kidney disease, heavy drinking and a weak immune system raise the risk, and children are more likely to have an infected bursa. A fever should be treated as infection until proven otherwise, but having no fever doesn't rule it out. Whatever the figures, heat, redness, broken skin over the swelling or feeling unwell needs a same-day check.

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What scans do and don't showEmerging evidence

Fluid in knee bursae is common in knees without symptoms. On MRI (magnetic resonance imaging) of 102 knees without symptoms, 49 had a fluid-filled bursa, most often the deep one behind the tendon below the kneecap. MRI 'bursitis' around the kneecap was found in 18% of graphic designers, who never kneel at work, and 16% of floor layers. On ultrasound, half of carpet and floor layers had a thickened bursa, but only 10 of 96 had fluid in it, and it was the fluid that went with pain when kneeling.

So a scan finding of fluid in a bursa doesn't prove bursitis. The diagnosis is made by examination, and a sample of fluid taken with a needle is what tests for infection or gout.

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How it usually goesEmerging evidence

Bursitis that isn't infected usually improves in a few weeks with rest from kneeling and self-care. It can come back with continued kneeling, which is why prevention matters.

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How it differs from the knee's other lumps and bursae

Pain a few centimetres below the joint on the inner shin, worse on stairs and getting out of a chair, without a swelling on the front, is pes anserine pain. A soft lump at the back of the knee is usually a Baker's cyst, which can burst and look like a clot. Pain on the tendon just below the kneecap that rises with jumping is jumper's knee. Pain either side of that tendon, worse as the knee straightens fully, without a soft swelling on the front of the kneecap, may be the fat pad being pinched (fat pad impingement). Each has its own guide.

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Self-care firstStrong evidence

The NHS advises resting the joint and avoiding pressure on it, an ice pack wrapped in a tea towel for about 10 minutes at a time every few hours, paracetamol or ibuprofen, and extra cushions around the knee at night; it should go away in a few weeks. An NHS trust adds avoiding kneeling, and using cushioning or knee pads in future.

The American Academy of Orthopaedic Surgeons (AAOS) suggests cycling or an elliptical trainer instead of kneeling activities, ice 3 or 4 times a day for 20 minutes, and raising the leg. A firm bandage is part of a UK GP reference's treatment, and in a trial of elbow bursitis, the authors judged a compression bandage with anti-inflammatory tablets the best balance of safety and effect.

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Draining it (aspiration): mainly a testMixed evidence

A GP may take fluid with a needle to test for infection and gout, which may also ease the swelling. The AAOS drains it if infection is suspected, or if swelling and pain don't respond to self-care. A German review's treatment plan drains both infected and non-infected bursitis, partly to tell them apart. A US review advises draining whenever infection is suspected, but not routinely for clearly non-infected bursitis from kneeling, because the needle can carry infection in; when it is done, a compression bandage afterwards may stop the fluid coming back.

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Steroid injections: thin evidenceMixed evidence

No trial has tested steroid injections for knee bursitis: a 2025 appraisal by an NHS physiotherapist found no studies from 2015 to 2025. The only randomised evidence is in the elbow. In 90 people, compression and anti-inflammatory tablets cleared the bursitis in 83% by 4 weeks, draining in 65%, and draining plus a steroid injection in 85%. The steroid group settled fastest (2.3 weeks, against about 3), but the trial was small, and its authors favoured compression and tablets for safety. A review of elbow bursitis found steroid shortened symptoms but brought more complications, including infection and thinning of the skin, and advised keeping it for bursitis that doesn't settle.

Guidance differs. The NHS lists steroid injections (not for infection), one NHS trust keeps them for when everything else has failed and the bursitis still severely affects work or sport, a German review suggests them for people with high work or sport demands, and a US review advises against routine use in bursitis from kneeling. When gout or rheumatoid arthritis is the cause, a steroid injection into the bursa is often used.

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Infected bursitis: antibiotics, and sometimes surgeryEmerging evidence

Infected bursitis is treated with antibiotics: by mouth if it is mild and you're otherwise well, or in hospital through a drip if you're unwell, have a weak immune system or the skin infection is spreading. The NHS says the course lasts at least 7 days. In 272 French patients, most settled without surgery, 26% had an operation, and treatment failed in 5.9%, more often with courses under 14 days.

In a trial of 164 hospital patients with infected elbow or knee bursitis, removing the bursa in one operation failed no more often than doing it in two (10% against 16%), with shorter stays. The 2023 French recommendations cover tests, antibiotic choices and durations, and when to operate.

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Surgery: rarelyEmerging evidence

Rarely, a bursa that is severe or keeps coming back is drained or removed (a bursectomy). Across 10 studies (702 patients), keyhole and open removal had similar rates of the bursitis coming back at a year, and similar complications, and 80% were free of pain a year after keyhole surgery.

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Prevention: pads, breaks and less kneelingEmerging evidence

Use padding when kneeling and take regular breaks (the NHS); wear kneepads at work and in contact sports, rest the knees regularly and switch tasks (the AAOS). In lab studies, kneepads lowered and spread the pressure on the knee, but high pressure points remained, and the design of the pad changed how the force was spread, so breaks and less kneeling still matter.

In Danish floor layers, training in tools and working methods that cut kneeling was still in use by 38% two years later (against 16% of untrained floor layers), and severe knee complaints were rarer in those who had used the methods for longer. Carpet layers' bursitis was linked with kicking a knee kicker. In the UK, people whose bursitis is caused by kneeling at work may be able to claim Industrial Injuries Disablement Benefit.

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Exercise doesn't treat the bursaEmerging evidence

Exercise isn't a treatment for bursitis, and no study has tested it. Keeping the knee moving and the thigh strong while avoiding pressure on the front of the knee is sensible, and in line with NHS advice to rest the joint from pressure and the AAOS's suggestion of cycling instead of kneeling. The plan below is our editorial starting point, not a tested treatment.

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Kneeling at work

Use a thick pad or a kneeling mat, kneel on the other knee, or squat or sit on a low stool for low tasks. Take regular breaks, stand up and stretch your legs, and switch tasks. Carpet layers who used a knee kicker to stretch carpet had more bursitis, and in floor layers, tools and methods that cut kneeling reduced severe knee complaints, so it's worth asking about other tools at work.

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Look after the skin over the knee

Germs can get into the bursa through a cut, scratch, graze or bite, so clean and cover any break in the skin over the knee, and watch for redness, heat or a high temperature. Leave draining to a clinician: squeezing or pricking the swelling yourself can let infection in.

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