Bursitis

Key Features

Essentials of Diagnosis

• Often occur around bony prominences where it is important to reduce friction

• Typically presents with locals swelling, which is painful acutely

• Septic bursitis can present without fever or systemic signs

General Considerations

• Inflammation of bursae may be secondary to

  • Trauma

  • Infection; most cases are caused by Staphylococcus aureus

  • Arthritic conditions, such as gout, rheumatoid arthritis, or osteoarthritis

• The two common sites are the olecranon and prepatellar bursae

• Others sites include

  • Subdeltoid bursa

  • Ischial bursa

  • Trochanteric bursa

  • Semimembranous-gastrocnemius (Baker cyst) bursa

• Bursitis can be septic or aseptic

Clinical Findings

Symptoms and Signs

• Tenderness, erythema and warmth, cellulitis

• Range of motion not affected

• Absence of fever does not exclude infection; one-third of those with septic olecranon bursitis are afebrile

• Bursa can become symptomatic when it ruptures; this is particularly true for Baker cyst, which can cause calf pain and swelling that mimics thrombophlebitis

Diagnosis

Laboratory Findings

• Acute swelling and redness calls for aspiration to rule out infection

  • A bursal fluid white blood cell count of > 1000/mcL (1 × 10⁹/L) indicates inflammation from infection, rheumatoid arthritis, or gout

  • The bursal fluid of septic bursitis characteristically contains

    • A purulent aspirate

    • Fluid-to-serum glucose ratio < 50%

    • White cell count > 3000 cells/mcL (3 × 10⁹/L)

    • Polymorphonuclear cells > 50%

    • Positive Gram stain for bacteria

  • Gram stain is positive for S aureus in two-thirds of cases

Imaging

• Unnecessary unless there is concern for osteomyelitis, trauma or other underlying pathology

• Ultrasonography or MRI easily show a ruptured Baker cyst; imaging a presumed Baker cyst can exclude deep venous thrombosis

Treatment

• For bursitis caused by trauma

  • Local heat

  • Rest

  • NSAIDs

  • Local corticosteroid injections

• For ruptured Baker cyst

  • Rest

  • Leg elevation

  • Injection of triamcinolone, 20–40 mg into the knee anteriorly (the knee compartment communicates with the cyst)

• Aspiration for chronic, stable olecranon bursa swelling usually not required

  • Runs the risk of creating a chronic drainage site, which can be reduced by using a "zig-zag" approach with a small needle (25-gauge if possible) and pulling the skin over the bursa before introducing it

  • Applying a pressure bandage may also help prevent chronic drainage

Therapeutic Procedures

• For septic bursitis

  • Incision and drainage

  • Antibiotics, usually delivered intravenously, especially against S aureus

Outcome

Prevention

• Avoid resting the elbow on a hard surface or wearing an elbow pad to eliminate repetitive minor trauma to the olecranon bursa

When to Refer

• Surgical ...