Prepatellar bursitis, often called housemaid's knee, is swelling of the small fluid-filled sac (bursa) in front of the kneecap. It is usually caused by repeated kneeling or a knock, and sometimes becomes infected.
A bursa is a thin, slippery sac that helps skin and soft tissues glide smoothly over bone. The prepatellar bursa lies just under the skin at the front of the kneecap. Repeated pressure from kneeling, or a direct blow, can irritate it so that it fills with fluid. This creates a soft, sometimes squishy swelling over the kneecap. The knee joint itself is usually not affected, so bending the knee is often still possible.
Because the bursa sits so close to the skin, germs can enter through a small cut, graze or insect bite and cause infection. This is called septic bursitis. It needs prompt treatment with antibiotics, as the infection can spread. Bursitis can also be linked to conditions such as gout or rheumatoid arthritis. Telling these types apart is an important part of the doctor's assessment.
The doctor asks about kneeling, injuries and any fever, then examines the swelling, the skin and how the knee moves. This helps show whether the problem is in the bursa or inside the knee joint.
Where it helps, an ultrasound scan can confirm fluid in the bursa and show how much there is. It can also help separate bursitis from swelling inside the knee joint.
If infection or gout is suspected, a small amount of fluid may be drawn off with a needle, where assessed as suitable. The fluid can be sent for laboratory testing to help guide treatment.
An X-ray may be arranged by referral after a fall to check for a fracture. If infection is severe or spreading, the clinic will refer you to hospital the same day.
Your plan depends on what the assessment finds. These are the options we most often discuss.
Avoiding kneeling and pressure on the knee lets the bursa settle. Knee pads or a kneeling cushion may help stop it coming back when you do need to kneel.
Simple pain relief or anti-inflammatory medicines, where suitable for you, and cold packs may help ease pain and swelling.
Infected (septic) bursitis needs antibiotics started promptly, with close follow-up. Severe or spreading infection may need hospital care, antibiotics through a drip or surgical drainage, and the clinic will refer you urgently.
Draining fluid from a large or tense bursa with a needle may ease pain and pressure where assessed as suitable. The fluid can build up again, so a compression bandage is often used afterwards.
Learn moreOnce infection has been ruled out, a corticosteroid injection into a persistent, non-infected bursa may occasionally be considered. It carries a risk of infection and skin changes, so it is used selectively.
Learn moreIf bursitis keeps coming back despite treatment, the clinic can refer you to an orthopaedic surgeon to discuss removing the bursa.
Non-infected bursitis often settles over a few weeks once pressure on the knee is avoided, although larger swellings can take longer. Infected bursitis usually starts to improve within a few days of starting antibiotics, but the full course needs to be finished and follow-up is important. Bursitis can come back if kneeling continues without protection. Recovery time varies with the cause, the size of the swelling and the demands of your work or activities.
Signs of infection include increasing redness, warmth, throbbing pain, fever or feeling unwell. There may be a cut or graze near the swelling. Infected and non-infected bursitis can look alike, so it is safest to see a doctor the same day if you are unsure.
Not always. Many non-infected swellings settle with rest and protection. Drainage may be considered if the swelling is large and painful, or to test the fluid when infection or gout is suspected. The fluid can build up again after drainage.
Often yes, with changes. Using knee pads or a kneeling mat, taking regular breaks and switching to a low stool where possible can reduce pressure on the bursa. If the bursa is infected, your doctor may advise time away from kneeling work until it has settled.
No. In prepatellar bursitis the swelling sits in front of the kneecap, just under the skin. Water on the knee usually refers to fluid inside the knee joint, which has different causes such as injury or arthritis. An examination, sometimes with an ultrasound scan, helps tell them apart.
No. Inflexion Clinic is a private GP clinic, so you can book directly. Book online or call the clinic on +65 8997 0659.
Our clinicians will take a proper history, examine you, and give you a clear plan on the day.