Overview
Knee bursitis is inflammation of a fluid-filled sac (bursa) around the knee, most commonly in front of the kneecap (prepatellar bursa), but it can also occur above or below it. The bursa normally reduces friction between moving tissues, and when it becomes irritated, it can swell and cause localized pain or a firm, tender bump. Symptoms often worsen with pressure, kneeling, or repetitive bending because increased friction and irritation keep the bursa inflamed. Most cases improve with nonsurgical care such as rest, anti-inflammatory measures, and guided activity changes.
Symptoms
Patients typically notice swelling over part of the kneecap or around the front of the knee, along with tenderness when pressing on the area. The knee may feel warm or look red, and pain is usually sharper with kneeling, squatting, or prolonged walking. Some people develop stiffness or reduced range of motion, especially if swelling becomes more significant. If infection is present, symptoms may progress quickly and may include fever or feeling ill.
Causes
Knee bursitis usually develops from repetitive pressure or friction, such as frequent kneeling, kneeling during work or sports, or frequent deep knee bending. It can also follow a direct blow to the knee, overuse from increased activity, or inflammatory conditions that affect the joints. In some cases, a bursa can become infected after skin breaks (even minor cuts) or through spread from nearby tissue.
Risk Factors
Risk is higher in people who kneel often, have physically demanding jobs, or participate in activities that involve repetitive squatting or frequent knee impact. Aging-related tissue fragility, prior knee injury, and poor training load management can contribute to irritation over time. Certain medical conditions that increase inflammation or infection risk, and skin problems near the knee, also raise the likelihood of bursitis.
Prevention
You can reduce flares by avoiding prolonged kneeling and using protective knee pads when kneeling is unavoidable. Gradually increasing activity intensity, maintaining strength in the hips and thighs, and using proper technique for squatting and lifting can lower repetitive stress on the bursa. Keeping skin clean and promptly treating cuts or abrasions near the knee helps prevent infection-related bursitis.
How the Diagnosis Is Evaluated
Clinicians start with a history focused on recent pressure, kneeling, injury, new activity, and whether there are infection symptoms such as fever or rapidly worsening redness. A physical exam checks for focal swelling, warmth, tenderness, and range of motion, and compares it to the other knee. In typical cases, imaging is not always necessary, but ultrasound can confirm bursal fluid and help guide aspiration if needed; X-ray or MRI may be considered if symptoms don't fit bursitis or if another problem is suspected. If infection is a concern, aspiration may be performed to analyze the fluid and determine the safest treatment.
Nonsurgical Treatment Options
Most knee bursitis is treated with relative rest and avoiding the movements or positions that trigger pain, especially kneeling and repetitive bending. Ice can help early inflammation, while later heat and gentle range-of-motion can improve comfort and mobility. Nonsteroidal anti-inflammatory drugs (NSAIDs) or topical anti-inflammatory options may reduce pain and swelling if they are safe for you. Physical therapy often helps by addressing mechanics, improving hip and thigh strength, and teaching activity modifications to prevent recurrence. If symptoms persist and the bursa is significantly inflamed, a clinician may aspirate excess fluid and may consider a corticosteroid injection to calm inflammation, typically with careful assessment to rule out infection first. In selected chronic, stubborn cases, some practices may use platelet-rich plasma (PRP) injections as an adjunct, but results can vary and it is not always a standard first-line option.
When to Seek Medical Attention
Seek prompt medical attention if you have fever, rapidly increasing redness or warmth, severe pain, or feel unwell, because these can indicate septic (infected) bursitis or another urgent problem. Get urgent care if you cannot bear weight, the swelling becomes extreme, or you notice worsening symptoms over hours to a day. Contact a clinician soon if symptoms do not improve after a reasonable period of conservative care, if the swelling keeps recurring, or if the diagnosis is uncertain. Also seek evaluation for numbness, major functional loss, or new symptoms that suggest nerve or blood flow issues.
Frequently Asked Questions
Mild cases often improve with rest, icing, and avoiding pressure on the knee, but persistent or recurrent swelling should be evaluated.
Avoid kneeling and repetitive bending, use ice early, and use OTC anti-inflammatory medication if safe for you; a clinician may offer aspiration or a targeted corticosteroid injection if it's severe.
Next Steps
If your swelling is mild and you do not have fever or rapidly worsening redness, start with activity modification, ice, and OTC pain control if appropriate, then monitor improvement over several weeks. If symptoms are severe, increasing, or not improving, arrange an evaluation to confirm the diagnosis and discuss targeted options such as ultrasound guidance, aspiration, or anti-inflammatory injection when appropriate.