Knee bursitis is swelling of a bursa, a small fluid-filled sac that cushions the knee where skin, tendon and bone rub together.
Most knee bursitis settles in a FEW WEEKS once you stop kneeling on it, with ice, rest and simple pain relief.
The exception: if the swelling is red and hot, and especially if you have a fever or feel unwell, it may be INFECTED. That needs a doctor the same day.
The three common types
- Prepatellar bursitis (housemaid’s knee): a soft, squashy swelling right on the front of the kneecap. The most common type, usually from kneeling
- Infrapatellar bursitis (clergyman’s knee): swelling just below the kneecap, over the tendon that joins the kneecap to the shinbone. Linked to kneeling upright and to jumping sports
- Pes anserine bursitis: pain and tenderness on the inner side of the knee, about 2 to 3 inches below the joint line. Common in runners and in people with knee arthritis
Who gets it
- Kneeling jobs: plumbers, roofers, carpet and floor layers, tilers, gardeners and cleaners
- Contact and floor sports: wrestling, football and basketball, where you land on the knee
- A single hard fall onto the front of the knee
- A cut or graze over the kneecap, which can let bacteria into the bursa
- Gout or rheumatoid arthritis, which can inflame the bursa without any injury
- For pes anserine bursitis: knee arthritis, extra body weight, tight hamstrings, and repetitive running or cycling
Symptoms
- A lump or puffiness over the kneecap, just below it, or on the inner knee
- Pain when kneeling or pressing on the spot
- Pain on stairs or getting up from a chair, typical of pes anserine bursitis
- Tenderness and some warmth over the swelling
- The knee usually still bends, though it may feel tight when fully bent
Is it bursitis or something else?
- Swelling on top of the kneecap that feels like a water balloon points to bursitis
- Swelling of the whole knee that makes it hard to bend is fluid INSIDE the joint, which has other causes. See knee arthritis
- A lump at the back of the knee is usually a different kind of swelling. See Baker’s cyst
- Pain in the tendon below the kneecap during jumping, with little swelling, is more often tendon trouble. See jumper’s knee
The bursa is there to protect your knee from pressure. Take the pressure away and it usually calms down.
What helps
- Stop kneeling on it: this is the most important step. If you must kneel for work, use thick knee pads or a kneeling mat, and take regular breaks
- Ice: about 20 minutes, 3 to 4 times a day, over a thin cloth
- Rest and elevation: ease off the activity that set it off, and raise the leg when you can
- Pain relief: over-the-counter anti-inflammatories can help if they are safe for you. Check with a pharmacist
- Exercises for pes anserine bursitis: hamstring stretches and strengthening for the thigh and hip take load off the inner knee
Most cases improve within a few weeks. Pes anserine bursitis can take longer, especially if knee arthritis is driving it.
When you need more than self-care
- Draining the fluid: a doctor can draw fluid out with a needle. This eases pressure and lets the fluid be tested for infection or gout
- Cortisone injection: sometimes used for stubborn swelling that isn’t infected. It is not used when infection is possible. See cortisone shot side effects
- Antibiotics: for infected bursitis, usually as tablets, sometimes through an IV
- Surgery: rarely needed. It is used to drain an infection that doesn’t clear with antibiotics, or to remove a bursa that keeps swelling up for months. Most people return to normal activities within a few weeks
The OrthoInfo guide to kneecap bursitis has more on treatment.
Go to the emergency department if
- You have a high fever or feel very unwell, confused or faint
- You can’t bend the knee at all, or the whole knee is hot and swollen
See a doctor the same day if
- The swollen area is red, hot and very tender
- Redness is spreading up or down the leg
- You have a fever, chills or feel unwell
- The swelling started after a cut, graze, bite or splinter over the knee
- You have diabetes or a weakened immune system and the knee is red or hot
Get it checked if
- It isn’t improving after 1 to 2 weeks of rest and ice
- The swelling keeps coming back
- A firm lump stays after the pain has gone
Knee bursitis is a pressure problem, so taking the pressure off fixes most of it. Heat, redness and fever make it an infection problem, and that can’t wait.