Bursal Cyst: Understanding Causes, Symptoms, Diagnosis, and Treatment

What is a bursal cyst?

A bursal cyst is a fluid-filled sac that forms when a bursa, a small, fluid-filled cushion located near joints, becomes inflamed or irritated, leading to an overproduction of synovial fluid and subsequent expansion of the bursa.

Understanding Bursae

Bursae (plural of bursa) are small, thin, slippery sacs filled with a lubricating fluid called synovial fluid. Their primary function is to reduce friction between moving structures in the body, such as between bones and tendons, bones and muscles, or tendons and skin. They act as natural cushions, allowing tissues to glide smoothly over one another during movement. Bursae are found throughout the body, particularly in areas subject to high friction and pressure, such as around major joints like the shoulders, elbows, hips, and knees.

What is a Bursal Cyst?

A bursal cyst is essentially an enlarged bursa. When a bursa becomes inflamed, a condition known as bursitis, it can lead to an increase in the production of synovial fluid within the sac. If this fluid accumulates excessively, the bursa expands and forms a palpable, often visible, lump – a bursal cyst. These cysts are typically benign (non-cancerous) and are a direct consequence of the body's response to irritation or injury of the bursa. While often associated with pain and discomfort, the cyst itself is a symptom of underlying bursitis.

Common Locations for Bursal Cysts

Bursal cysts can develop in any bursa, but they are most commonly found in areas prone to repetitive motion, direct pressure, or injury. Some of the most frequent locations include:

• Shoulder: The subacromial/subdeltoid bursa, located under the deltoid muscle and acromion, is a common site for bursitis and cyst formation, often due to overhead activities.
• Elbow: The olecranon bursa, covering the bony tip of the elbow, is susceptible to cysts (often called "student's elbow" or "miner's elbow") from direct trauma or prolonged leaning.
• Hip:
  • Trochanteric bursa: Located on the outer aspect of the hip, near the greater trochanter of the femur.
  • Iliopsoas bursa: Located on the inner aspect of the hip, near the groin.
• Knee:
  • Prepatellar bursa: On the front of the kneecap ("housemaid's knee").
  • Infrapatellar bursa: Below the kneecap ("clergyman's knee").
  • Pes anserine bursa: On the inner side of the knee, below the joint line.
  • Popliteal bursa (Baker's Cyst): A common type of bursal cyst that forms behind the knee, often associated with underlying knee joint issues like arthritis or meniscal tears.
• Heel/Ankle: The retrocalcaneal bursa (behind the heel, near the Achilles tendon) and the calcaneal bursa (under the heel bone) can also develop cysts.

Causes and Risk Factors

The development of a bursal cyst is almost always linked to factors that irritate or inflame a bursa. Common causes and risk factors include:

• Repetitive Motion or Overuse: Engaging in activities that involve repeated movements of a joint can cause chronic irritation to the bursa. This is common in athletes, certain occupations (e.g., carpenters, gardeners, painters), and those with hobbies involving repetitive actions.
• Direct Trauma: A sudden blow or fall directly onto a bursa can trigger inflammation and fluid accumulation.
• Prolonged Pressure: Sustained pressure on a bursa, such as kneeling for long periods (prepatellar bursa) or leaning on elbows (olecranon bursa), can lead to bursitis and cyst formation.
• Infection: While less common, bacteria can infect a bursa (septic bursitis), leading to severe inflammation, pain, and pus formation within the bursa, which can then present as a cyst.
• Systemic Conditions: Certain underlying medical conditions can predispose individuals to bursitis and bursal cysts, including:
  • Rheumatoid arthritis
  • Gout
  • Psoriatic arthritis
  • Diabetes
• Poor Biomechanics and Improper Form: Incorrect movement patterns or muscular imbalances can place undue stress on specific bursae, increasing their risk of irritation.
• Age: The risk of bursitis and bursal cysts tends to increase with age due to general wear and tear on joints and tissues.

Signs and Symptoms

The symptoms of a bursal cyst can vary depending on its size, location, and the degree of inflammation. Common signs and symptoms include:

• Visible Lump or Swelling: A soft, spongy, or sometimes firm lump can be felt or seen under the skin in the affected area.
• Pain and Tenderness: Localized pain that may worsen with movement of the adjacent joint or with direct pressure on the cyst.
• Limited Range of Motion: Pain and swelling can restrict the normal movement of the affected joint.
• Redness and Warmth: If the bursa is acutely inflamed or infected, the overlying skin may appear red and feel warm to the touch.
• Fever and Chills: These systemic symptoms are a strong indicator of an infection (septic bursitis) and warrant immediate medical attention.

Diagnosis

Diagnosing a bursal cyst typically involves a combination of medical history, physical examination, and imaging studies:

• Medical History: The doctor will inquire about the onset of symptoms, activities that exacerbate the pain, any history of injury, and underlying medical conditions.
• Physical Examination: The affected area will be inspected for swelling, redness, and tenderness. The range of motion of the adjacent joint will also be assessed.
• Imaging Studies:
  • Ultrasound: This is often the preferred initial imaging modality as it can clearly visualize fluid collections, determine the size and nature of the cyst, and differentiate it from solid masses.
  • Magnetic Resonance Imaging (MRI): Provides detailed images of soft tissues and can help confirm the diagnosis, rule out other conditions (like tumors or tendon tears), and assess the extent of inflammation.
  • X-rays: While X-rays cannot directly visualize bursae or cysts, they may be used to rule out bone spurs, fractures, or arthritis as contributing factors.
• Fluid Aspiration (Arthrocentesis): In some cases, a needle may be used to withdraw fluid from the cyst. This fluid can then be analyzed to check for signs of infection (bacteria, white blood cells) or the presence of crystals (indicating conditions like gout or pseudogout).

Treatment Options

Treatment for a bursal cyst primarily focuses on reducing inflammation, alleviating pain, and addressing the underlying cause. The approach often starts conservatively and may escalate if symptoms persist:

• Conservative Management:
  • Rest: Avoiding activities that aggravate the bursa is crucial.
  • Ice: Applying ice packs to the affected area for 15-20 minutes several times a day can help reduce pain and inflammation.
  • Compression: In some cases, a compression bandage can help reduce swelling, particularly for superficial bursal cysts.
  • Elevation: Elevating the affected limb can help reduce fluid accumulation and swelling.
• Medications:
  • Non-Steroidal Anti-Inflammatory Drugs (NSAIDs): Over-the-counter (e.g., ibuprofen, naproxen) or prescription NSAIDs can help manage pain and inflammation.
  • Antibiotics: If the bursal cyst is infected (septic bursitis), a course of antibiotics is necessary.
• Corticosteroid Injections: A corticosteroid, a powerful anti-inflammatory medication, can be injected directly into the bursa to reduce inflammation and pain. This is often combined with fluid aspiration.
• Aspiration: Draining the excess fluid from the cyst with a needle can provide immediate relief from pressure and swelling. This procedure is often followed by a corticosteroid injection.
• Physical Therapy: Once acute symptoms subside, a physical therapist can design an exercise program to improve flexibility, strengthen surrounding muscles, correct biomechanical imbalances, and reduce the risk of recurrence.
• Surgery (Bursactomy): Surgical removal of the bursa (bursactomy) is rarely necessary but may be considered for chronic, recurrent bursal cysts that do not respond to conservative treatment, or for persistent septic bursitis unresponsive to antibiotics.

Prevention Strategies

While not all bursal cysts can be prevented, several strategies can significantly reduce the risk of their development:

• Proper Ergonomics and Padding: Use knee pads when kneeling, elbow pads when leaning, or other protective padding during activities that involve sustained pressure on joints.
• Gradual Increase in Activity: Avoid sudden increases in the intensity, duration, or frequency of exercises or activities. Gradually build up strength and endurance to allow tissues to adapt.
• Warm-up and Cool-down: Always perform a proper warm-up before exercise to prepare muscles and joints, and a cool-down afterward to aid recovery.
• Correct Biomechanics and Form: Ensure proper form during exercise and daily activities. Seek guidance from a fitness professional or physical therapist if you suspect biomechanical issues.
• Appropriate Footwear and Gear: Wear supportive shoes and use appropriate sports equipment to minimize stress on joints.
• Manage Underlying Medical Conditions: Effectively manage conditions like arthritis, gout, or diabetes, as they can increase the risk of bursitis.
• Listen to Your Body: Avoid pushing through pain. If an activity causes discomfort, modify it or take a break.

When to Seek Medical Attention

While many bursal cysts resolve with conservative management, it's important to consult a healthcare professional if you experience:

• Persistent or worsening pain that doesn't improve with rest and home care.
• Increasing swelling or redness around the cyst.
• Signs of infection, such as fever, chills, or significant warmth radiating from the area.
• Inability to move the affected joint normally.
• Symptoms that interfere with your daily activities or sleep.
• Any new lump or swelling that appears unexpectedly.