What are the steps to diagnose bursitis?

Diagnosing Bursitis

The diagnosis of bursitis requires a combination of clinical assessment and targeted imaging, with ultrasound being the preferred initial imaging modality for suspected bursitis due to its high sensitivity for detecting fluid collections and soft tissue inflammation. 1

Clinical Assessment

History

• Location of pain (specific to bursa location)
• Onset (acute vs. chronic)
• Aggravating factors:
  • Pressure from shoes (retrocalcaneal bursitis) 1
  • Kneeling (prepatellar bursitis) 2
  • Increased activity 1
• Relieving factors (e.g., walking barefoot in Haglund's deformity) 1
• Previous trauma or repetitive microtrauma
• Systemic symptoms (fever, chills) suggesting infection

Physical Examination

• Localized tenderness over the affected bursa
• Swelling or visible fluid collection
• Erythema (suggests possible infection)
• Limited range of motion in adjacent joint
• Pain with specific movements:
  • Hip abduction (trochanteric bursitis)
  • Knee flexion (prepatellar bursitis)
  • Ankle dorsiflexion (retrocalcaneal bursitis)

Diagnostic Imaging

Ultrasound (First-Line Imaging)

• Highly recommended for suspected bursitis 1
• Advantages:
  • Non-invasive
  • Cost-effective
  • Can distinguish bursitis from cellulitis 2
  • Can guide aspiration and injection 1
• Findings:
  • Fluid collection in bursa
  • Synovial thickening
  • Hyperemia on Doppler imaging (in inflammatory cases)

Radiographs

• Should be obtained first in most cases of chronic joint pain 1
• Useful to:
  • Rule out fractures or bone abnormalities
  • Identify calcifications
  • Detect associated conditions (e.g., Haglund's deformity in retrocalcaneal bursitis) 1

MRI

• Indicated when:
  • Ultrasound is negative but clinical suspicion remains high
  • Need to assess surrounding soft tissues (tendons, muscles)
  • Differentiating between bursitis and tendinopathy 3
• Superior for evaluating peritrochanteric structures 3

Laboratory Testing (When Infection Suspected)

• Bursal aspiration with:
  • Gram stain
  • Cell count (WBC >2000/mm³ suggests infection)
  • Crystal analysis (to rule out gout)
  • Glucose measurement
  • Culture and sensitivity 2
• Blood tests:
  • Complete blood count
  • Erythrocyte sedimentation rate
  • C-reactive protein 2

Diagnostic Algorithm

1. Initial Assessment:

   • Clinical evaluation (history and physical examination)
   • Plain radiographs to rule out fractures or bone abnormalities

2. If Bursitis Suspected:

   • Ultrasound examination of the affected area
   • Look for fluid collection, synovial thickening, hyperemia

3. If Infection Suspected (fever, erythema, severe pain):

   • Immediate bursal aspiration under ultrasound guidance
   • Send fluid for analysis (cell count, Gram stain, culture)
   • Blood tests for inflammatory markers

4. If Diagnosis Remains Unclear:

   • MRI to evaluate surrounding structures
   • Consider other diagnoses (tendinopathy, arthritis)

Common Pitfalls and Caveats

• Trochanteric bursitis often coexists with gluteus medius tendinosis and can be difficult to differentiate 3
• Septic bursitis requires prompt diagnosis and treatment to prevent complications
• Avoid blind aspiration or injection due to risk of iatrogenic infection 2
• Bursitis may be secondary to underlying conditions (gout, rheumatoid arthritis) that require specific treatment 2
• Failure to detect a loose body in a joint does not rule out its presence 1

By following this systematic approach to diagnosis, clinicians can accurately identify bursitis and distinguish it from other musculoskeletal conditions, leading to appropriate treatment and improved patient outcomes.