Suprapatellar Bursitis: Causes, Symptoms, and Prevention

What causes suprapatellar bursitis?

Suprapatellar bursitis is an inflammation of the suprapatellar bursa, a fluid-filled sac located just above the kneecap (patella) and beneath the quadriceps femoris tendon, typically resulting from direct trauma, repetitive overuse, prolonged pressure, or underlying systemic conditions.

Understanding the Suprapatellar Bursa

The human body contains numerous bursae, small, slippery, fluid-filled sacs that act as cushions between bones, tendons, muscles, and skin. Their primary function is to reduce friction during movement, allowing structures to glide smoothly over one another.

The suprapatellar bursa is one of four major bursae surrounding the knee joint. It is strategically positioned between the quadriceps femoris tendon (the tendon connecting the quadriceps muscles to the patella) and the femur (thigh bone). It extends proximally (upwards) from the superior pole of the patella, often communicating with the knee joint capsule itself. This communication is clinically significant, as inflammation or infection of the bursa can sometimes affect the joint, and vice-versa.

What is Bursitis?

Bursitis is the general term for inflammation of a bursa. When a bursa becomes inflamed, the synovial fluid within it can increase, and its lining may thicken. This leads to symptoms such as:

• Pain: Often localized to the affected area, exacerbated by movement or pressure.
• Swelling: Visible enlargement due to fluid accumulation.
• Tenderness: Pain upon touch.
• Warmth and Redness: Especially if infection is present.
• Reduced Range of Motion: Due to pain and swelling.

Suprapatellar bursitis specifically affects the bursa above the kneecap, leading to pain and swelling in the area just proximal to the patella.

Primary Causes of Suprapatellar Bursitis

The inflammation of the suprapatellar bursa can arise from several distinct mechanisms:

Direct Trauma or Impact

One of the most common causes is a direct blow or fall onto the front of the thigh, just above the kneecap. This acute trauma can directly irritate and inflame the bursa, causing immediate swelling and pain. Examples include:

• Falling directly onto the knee.
• Impact from sports activities (e.g., a direct kick to the thigh in soccer).
• Accidental collisions.

Repetitive Stress and Overuse

Chronic, repetitive strain on the quadriceps tendon can lead to low-grade inflammation of the underlying suprapatellar bursa. This is particularly common in activities that involve repeated knee flexion and extension, or sustained quadriceps engagement.

• Repetitive squatting or lunging: Activities like weightlifting, certain dance forms, or manual labor.
• Running or jumping sports: Especially those with poor biomechanics or sudden increases in training volume.
• Cycling: If saddle height or pedaling technique puts undue stress on the quadriceps.
• Excessive stair climbing or descending.

Prolonged Pressure or Friction

Sustained pressure on the bursa can also lead to inflammation. While less common for the suprapatellar bursa than the prepatellar bursa ("housemaid's knee"), certain postures or activities can contribute:

• Prolonged kneeling with the knee excessively flexed: Though more typical for prepatellar bursitis, certain occupational postures might indirectly affect the suprapatellar bursa.
• Tight clothing or equipment: That constantly rubs against the area.

Infection (Septic Bursitis)

Though less frequent than aseptic (non-infectious) causes, the suprapatellar bursa can become infected. This typically occurs when bacteria enter the bursa through a break in the skin near the knee, such as a cut, scrape, insect bite, or puncture wound.

• Symptoms: Septic bursitis presents with more severe pain, significant warmth, redness, and often fever and chills. It requires urgent medical attention and antibiotic treatment.

Underlying Medical Conditions

Certain systemic diseases can predispose individuals to bursitis, including suprapatellar bursitis. These conditions cause inflammation throughout the body, and the bursae can be affected.

• Rheumatoid Arthritis: An autoimmune disease causing chronic joint inflammation.
• Gout: A form of arthritis caused by the accumulation of uric acid crystals in joints and soft tissues.
• Pseudogout (Calcium Pyrophosphate Deposition Disease): Similar to gout, but caused by calcium pyrophosphate crystals.
• Other inflammatory arthritides: Such as psoriatic arthritis or ankylosing spondylitis.

Risk Factors Contributing to Suprapatellar Bursitis

Several factors can increase an individual's susceptibility to developing suprapatellar bursitis:

• Occupations: Jobs requiring prolonged or repetitive knee movements, or those with a high risk of direct knee trauma (e.g., athletes, construction workers, carpet layers).
• Athletic Activities: Sports involving frequent jumping, squatting, or direct knee impact (e.g., basketball, volleyball, wrestling, contact sports).
• Poor Biomechanics: Imbalances in muscle strength around the knee, poor running or lifting form, or inadequate footwear can increase stress on the quadriceps tendon and bursa.
• Muscle Imbalances: Tight quadriceps, weak hamstrings, or gluteal muscles can alter knee mechanics and increase strain.
• Previous Knee Injury: A history of knee trauma or surgery can alter joint mechanics and predispose to bursitis.
• Age: The risk of bursitis generally increases with age due to wear and tear and decreased tissue elasticity.
• Obesity: Increased body weight can place additional stress on the knee joint and surrounding structures.
• Diabetes: Individuals with diabetes may have a higher risk of developing septic bursitis due to compromised immune function.

Recognizing the Symptoms

While the focus is on causes, understanding the symptoms helps confirm the presence of suprapatellar bursitis:

• Pain: Located just above the kneecap, often worse with knee flexion, extension, or direct pressure.
• Swelling: A noticeable lump or puffiness superior to the patella.
• Tenderness: Pain upon palpation of the bursa.
• Warmth and Redness: Indicative of significant inflammation, especially if infectious.
• Limited Range of Motion: Difficulty fully bending or straightening the knee due to pain and swelling.

Diagnosis and Management

Diagnosis typically involves a clinical examination, including palpation and assessment of range of motion. Imaging studies like ultrasound or MRI can confirm the diagnosis, rule out other conditions, and assess the extent of inflammation. In cases of suspected infection, fluid aspiration from the bursa for laboratory analysis is crucial.

Management generally involves conservative measures such as:

• Rest: Avoiding aggravating activities.
• Ice: Applying cold packs to reduce inflammation.
• Compression: Using a bandage to minimize swelling.
• Elevation: Raising the leg to reduce fluid accumulation.
• Non-steroidal anti-inflammatory drugs (NSAIDs): To manage pain and inflammation.
• Physical Therapy: To address underlying biomechanical issues, strengthen surrounding muscles, and improve flexibility.
• Corticosteroid Injections: To reduce inflammation in persistent cases.
• Aspiration: Draining excess fluid from the bursa.
• Surgery (Bursectomy): Rarely, removal of the bursa may be necessary for chronic, recurrent, or septic cases unresponsive to conservative treatment.

Prevention Strategies

Preventing suprapatellar bursitis largely revolves around minimizing the risk factors:

• Proper Warm-up and Cool-down: Prepare muscles and joints for activity and aid recovery.
• Gradual Increase in Activity: Avoid sudden increases in training intensity or volume.
• Correct Biomechanics: Learn and practice proper form for exercises and sports. Consider professional coaching or physical therapy for gait analysis or movement assessment.
• Strengthening and Flexibility: Maintain balanced strength in the quadriceps, hamstrings, and glutes, and ensure adequate flexibility of the surrounding musculature.
• Ergonomic Adjustments: Use knee pads or cushions if occupations or activities involve prolonged kneeling or pressure on the knee.
• Appropriate Footwear: Wear supportive shoes suitable for your activity.
• Address Underlying Conditions: Effectively manage systemic inflammatory diseases.
• Protect the Knee: Use protective gear during contact sports or activities with a high risk of direct impact.

When to Seek Medical Attention

While many cases of suprapatellar bursitis can be managed conservatively, it's important to seek medical attention if:

• Pain and swelling are severe or rapidly worsening.
• You experience fever, chills, or significant redness and warmth around the knee (signs of infection).
• Symptoms do not improve with rest and self-care within a few days.
• You are unable to move your knee or bear weight on your leg.

Understanding the causes of suprapatellar bursitis empowers individuals to take proactive steps in prevention and seek timely, appropriate care when symptoms arise.