Knee Bursitis: Causes, Symptoms, and Treatment
Also known as: prepatellar bursitis, pes anserine bursitis, kneecap bursitis, housemaid's knee
What is knee bursitis?
Knee bursitis is inflammation of a bursa, a small fluid-filled sac located around the knee joint. These sacs cushion the joint and help reduce friction between bone and the nearby muscles, tendons, and skin. Two common types are prepatellar bursitis (in front of the kneecap), the most frequently affected bursa of the knee, and pes anserine bursitis (on the inner side of the knee). It is fairly common, affecting athletes as well as people whose work involves prolonged kneeling. In the United States, it is a frequent cause of pain around the knee joint.
Causes and risk factors
Knee bursitis most often results from repeated mechanical irritation or a direct injury. Main causes and risk factors include:
- Repeated microtrauma from certain jobs (carpet layers, gardeners, plumbers, roofers)
- Contact and high-impact sports (football, wrestling, basketball)
- A direct blow to the front of the knee
- Obesity, which increases stress on the joint
- Rheumatic conditions such as rheumatoid arthritis or gout
- Bacterial infection (septic bursitis), which is rarer but serious and can occur when bacteria enter through a break in the skin
Symptoms
Symptoms of knee bursitis can develop gradually or suddenly depending on the cause. The most common are:
- Localized pain around the knee, worse with pressure or movement
- Visible, palpable swelling over the inflamed bursa
- Redness and warmth with intense inflammation or infection
- Joint stiffness, especially after waking or sitting for a long time
- Functional limitations affecting walking, climbing stairs, or kneeling
When the bursa is infected, swelling and redness may be accompanied by fever and chills.
Diagnosis
The doctor diagnoses knee bursitis mainly through a clinical exam: inspection, palpation, and comparing the affected knee with the healthy one. Additional tests may be ordered to confirm the diagnosis or guide treatment:
- An X-ray to rule out a fracture or bone involvement
- MRI or CT imaging to assess the surrounding soft tissues
- Aspiration of the bursa if infection or gout is suspected, with fluid analysis
Treatment
Treatment depends on the cause and severity. Most cases improve with nonsurgical care:
- Relative rest and activity modification, steering clear of movements that aggravate the knee
- Ice packs applied 3 or 4 times a day for about 20 minutes at a time to reduce inflammation
- Elevation of the leg to help limit swelling
- Oral NSAIDs (ibuprofen, naproxen) to relieve pain and inflammation
- Aspiration of the bursa for significant fluid buildup, sometimes followed by a corticosteroid injection into the bursa when other measures fail
- Antibiotics tailored to the infection if the bursitis is septic
- Physical therapy to strengthen the muscles around the joint and prevent recurrence
If the bursa does not improve after 6 to 12 months of conservative treatment, surgery may be considered to drain or remove it.
Prevention
Several measures help prevent knee bursitis or its recurrence:
- Wear protective knee pads during higher-risk activities (kneeling work, contact sports)
- Strengthen the muscles around the knee with regular, appropriate exercise
- Maintain a healthy weight to reduce stress on the joint
- Use ergonomic postures at work and during sports
- Warm up properly before physical activity
- Avoid prolonged kneeling without protection
When should you see a doctor?
See a doctor promptly if the pain is intense or worsens despite rest, if the knee is very red, warm, and swollen (signs of infection), if you have a fever, or if functional limitations persist beyond a few days. Untreated septic bursitis can lead to serious complications.
Sources
- OrthoInfo, American Academy of Orthopaedic Surgeons (AAOS), patient education on prepatellar (kneecap) bursitis
- MedlinePlus, U.S. National Library of Medicine health information
- Prepatellar Bursitis, StatPearls (NCBI Bookshelf, NIH), the prepatellar bursa as the most commonly affected bursa of the knee
- Pes Anserine Bursitis, StatPearls (NCBI Bookshelf, NIH), pes anserine bursitis as a common cause of medial knee pain