Knee Bursitis: Causes, Symptoms, and Treatment

What is Knee Bursitis?

Knee bursitis is a painful condition that occurs when one or more of the bursae (small, fluid-filled sacs) in or around your knee joint become inflamed. Bursae act as cushions between bones, tendons, and muscles, reducing friction during movement. When these sacs become irritated or infected, they swell, causing discomfort and limited mobility.

There are several bursae around the knee, but the most commonly affected are:

• Prepatellar bursa – Located in front of the kneecap (patella).
• Pes anserine bursa – Located on the inner side of the knee, below the joint.
• Infrapatellar bursa – Located just below the kneecap.

Knee bursitis is often temporary but can become chronic if not properly treated. It is common in people who spend a lot of time kneeling (e.g., gardeners, carpet layers) or those who engage in repetitive knee movements (e.g., runners, athletes).

Source: Mayo Clinic, Arthritis Foundation

Common Causes

Knee bursitis can develop due to a variety of factors, including:

• Repetitive knee movements – Activities like running, jumping, or cycling can irritate the bursae over time.
• Prolonged kneeling – Jobs or hobbies that require frequent kneeling (e.g., plumbing, gardening, cleaning) increase pressure on the bursae.
• Direct trauma or injury – A hard blow to the knee, such as falling or hitting it against a hard surface, can cause inflammation.
• Infection – Bacteria can enter the bursa through a cut or puncture wound, leading to septic bursitis, a more serious condition requiring antibiotics.
• Overuse or strain – Sudden increases in physical activity, such as training for a marathon, can overload the knee joints.
• Arthritis – Conditions like osteoarthritis or rheumatoid arthritis can contribute to bursitis due to joint stress and inflammation.
• Gout or pseudogout – Crystal deposits in the joint can irritate the bursae.
• Obesity – Excess weight puts additional stress on the knee joints.
• Poor posture or alignment – Issues like knock-knees or flat feet can alter knee mechanics, leading to bursitis.
• Previous knee surgery – Surgical procedures or implants can irritate nearby bursae.

Source: Cedars-Sinai, American Academy of Orthopaedic Surgeons (AAOS)

Associated Symptoms

Symptoms of knee bursitis can vary depending on which bursa is affected, but common signs include:

• Pain – Often worsens with movement, kneeling, or pressure on the knee.
• Swelling – The knee may appear puffy or feel "squishy" due to fluid buildup.
• Redness and warmth – The skin over the affected area may become warm to the touch, especially if infection is present.
• Stiffness – Difficulty bending or straightening the knee, particularly after periods of inactivity.
• Tenderness – The area around the bursa may be sensitive to touch.
• Limited range of motion – Difficulty with activities like climbing stairs, squatting, or kneeling.
• Sharp pain with certain movements – For example, pain when going up or down stairs (common with pes anserine bursitis).

In cases of septic bursitis (caused by infection), additional symptoms may include:

• Fever or chills
• Severe redness or streaking around the knee
• Pus or drainage from the area

Source: National Center for Biotechnology Information (NCBI), Johns Hopkins Medicine

When to See a Doctor

While mild cases of knee bursitis may improve with rest and home care, you should consult a healthcare provider if you experience:

• Severe or worsening pain that doesn’t improve with rest.
• Significant swelling, redness, or warmth around the knee.
• Fever or chills, which may indicate an infection.
• Difficulty bearing weight on the affected leg.
• Symptoms that persist for more than a week despite home treatment.
• Recurrent episodes of bursitis.

Early medical evaluation can help prevent complications, such as chronic pain or joint damage.

Diagnosis

To diagnose knee bursitis, your doctor will typically:

• Review your medical history – Including recent activities, injuries, or illnesses.
• Perform a physical exam – Checking for swelling, tenderness, and range of motion in the knee.
• Order imaging tests – Such as X-rays (to rule out fractures or arthritis) or ultrasound/MRI (to visualize the bursa and surrounding structures).
• Aspirate the bursa – Using a needle to drain fluid from the bursa for analysis. This helps determine if the bursitis is caused by infection, gout, or other conditions.
• Blood tests – To check for signs of infection or inflammatory conditions like rheumatoid arthritis.

Accurate diagnosis is essential to rule out other conditions with similar symptoms, such as tendonitis, meniscus tears, or arthritis.

Source: Cleveland Clinic, National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS)

Treatment Options

Treatment for knee bursitis depends on the cause and severity but often includes a combination of medical and home remedies.

Home Treatments

• Rest – Avoid activities that worsen symptoms, such as kneeling or excessive walking.
• Ice therapy – Apply ice packs to the knee for 15-20 minutes, 3-4 times a day, to reduce swelling.
• Compression – Use an elastic bandage to wrap the knee snugly (but not too tightly) to limit swelling.
• Elevation – Prop your leg up on a pillow when sitting or lying down to reduce fluid buildup.
• Over-the-counter pain relievers – Nonsteroidal anti-inflammatory drugs (NSAIDs) like ibuprofen or naproxen can help reduce pain and inflammation.
• Knee pads or cushions – Use protective padding if your job or hobbies require kneeling.

Medical Treatments

• Corticosteroid injections – A doctor may inject a steroid medication into the bursa to reduce severe inflammation.
• Antibiotics – If the bursitis is caused by infection (septic bursitis), oral or intravenous antibiotics will be prescribed.
• Physical therapy – A therapist can teach exercises to strengthen the muscles around the knee and improve flexibility.
• Aspiration – Draining fluid from the bursa with a needle to relieve pressure and pain.
• Surgery – In rare cases, if bursitis is chronic or doesn’t respond to other treatments, the bursa may be surgically removed (bursectomy).

Source: Mayo Clinic, Arthritis Foundation

Prevention Tips

While not all cases of knee bursitis can be prevented, the following strategies can reduce your risk:

• Use knee pads – Wear protective gear when kneeling for work or hobbies.
• Take frequent breaks – Avoid prolonged kneeling or repetitive knee movements.
• Warm up and stretch – Before exercising, warm up with light activity and stretch your leg muscles.
• Strengthen your legs – Exercises like leg lifts, hamstring curls, and quad sets can support knee stability.
• Maintain a healthy weight – Excess weight puts extra stress on your knees.
• Wear proper footwear – Shoes with good arch support and cushioning can improve knee alignment.
• Gradually increase activity – Avoid sudden increases in exercise intensity or duration.
• Practice good posture – Proper body mechanics can reduce strain on your knees.

Source: American Council on Exercise (ACE), Hospital for Special Surgery (HSS)

Emergency Warning Signs

Seek immediate medical attention if you experience any of the following:

• High fever (over 101°F or 38.3°C) with knee pain and swelling.
• Severe redness, warmth, or streaking around the knee, which may indicate a spreading infection.
• Inability to move the knee or bear weight on the affected leg.
• Signs of a blood clot, such as sudden calf pain, swelling, or redness (seek emergency care).
• Pus or foul-smelling drainage from the knee.

These symptoms may indicate a serious infection (e.g., septic bursitis or cellulitis) or other medical emergencies requiring prompt treatment.

Source: Centers for Disease Control and Prevention (CDC), World Health Organization (WHO)