What is crepitus?

Understanding Crepitus: Clinical Significance and Diagnostic Implications

Crepitus is a crackling or grinding sound and/or sensation produced during joint or tissue movement, which can indicate various underlying pathologies ranging from benign joint conditions to life-threatening infections. 1

Types of Crepitus

1. Articular Crepitus

• Definition: Joint grating or popping sounds most commonly associated with arthritis 1
• Characteristics:
  • Often heard during joint movement
  • May or may not be accompanied by pain
  • More common with increasing frequency of occurrence 2
• Clinical significance:
  • Predictive of incident symptomatic knee osteoarthritis in patients with pre-existing radiographic changes 2
  • Associated with osteophytes in patellofemoral and lateral tibiofemoral joints 3
  • In the medial tibiofemoral compartment, associated with osteophytes and medial collateral ligament pathology 3

2. Soft-Tissue Crepitus

• Definition: Crackling sensation felt in soft tissues, often indicating presence of gas 1
• Causes:
  • Benign: Subcutaneous emphysema after trauma or surgical procedures 4
  • Serious: Gas-producing bacterial infections such as necrotizing fasciitis or gas gangrene 1
• Clinical significance:
  • Critical to differentiate between benign subcutaneous emphysema and life-threatening infections 4
  • When associated with soft-tissue gas in the absence of recent trauma, surgery, or puncture wound, highly suggestive of infection 1

3. Laryngeal Crepitus

• Definition: Sensation felt when moving the larynx from side to side with slight posterior pressure 5
• Clinical significance:
  • Absence may indicate trauma to the larynx or hypopharynx 5
  • Temporary absence documented in cases of non-fatal strangulation 5

Diagnostic Approach to Crepitus

Initial Assessment

1. Location and characteristics:

   • Joint-related vs. soft tissue
   • Associated pain, swelling, or erythema
   • Timing and triggers

2. Context and history:

   • Recent trauma, surgery, or puncture wounds
   • History of arthritis or joint disease
   • Systemic symptoms (fever, chills)

Red Flags Requiring Urgent Evaluation

• Soft tissue crepitus with:
  • Fever, tachycardia, or diaphoresis
  • Rapidly spreading erythema or skin changes
  • Pain disproportionate to clinical findings
  • Systemic toxicity or altered mental status
  • Skin necrosis or ecchymoses 1

Diagnostic Imaging for Crepitus

For Joint Crepitus

• Plain radiographs: Initial assessment for arthritis, fractures
• MRI: Gold standard for detailed evaluation of joint structures, particularly useful for detecting cartilage damage, meniscal tears, and ligamentous injuries 3

For Soft Tissue Crepitus

• Plain radiographs: Well-suited for detecting soft-tissue gas in extremities but limited for deep fascial gas 1
• CT scan: Most sensitive for detecting soft-tissue gas; can delineate extent and compartmental location 1
• MRI: Less sensitive than CT for gas detection; gradient-echo imaging can help identify air by magnifying susceptibility artifact 1
• Ultrasound: Useful for bedside evaluation, especially when CT is unavailable; can demonstrate marked soft tissue thickening, inflammation, and subcutaneous gas 1

Management Considerations

For Articular Crepitus

• Often managed conservatively with:
  • Postural and strengthening exercises
  • Local modalities
  • Anti-inflammatory medications 6
• Surgical options for refractory cases:
  • Partial scapulectomy (for scapulothoracic crepitus)
  • Open or arthroscopic bursectomy 6

For Soft Tissue Crepitus with Suspected Infection

• Immediate surgical exploration when necrotizing fasciitis is suspected 1
• Broad-spectrum antibiotics covering aerobic and anaerobic organisms 1
• Repeated surgical debridement until no further necrotic tissue is found 1

Clinical Pearls

1. The presence of soft tissue crepitus without recent trauma, surgery, or puncture wound should be considered a reliable indication of infection until proven otherwise 1

2. In patients with knee pain, subjective crepitus predicts incident symptomatic osteoarthritis, particularly in those with pre-existing radiographic changes 2

3. The frequency of crepitus correlates with risk of developing symptomatic osteoarthritis - patients reporting crepitus "always" have three times higher odds compared to those never experiencing it 2

4. Soft tissue crepitus with systemic toxicity, particularly in immunocompromised patients or those with diabetes, should prompt immediate evaluation for necrotizing fasciitis 1

5. CT is the imaging modality of choice for evaluating soft tissue gas, but imaging should never delay surgical intervention in patients with suspected necrotizing fasciitis 1