What are the causes of sternum crepitus?

Causes of Sternum Crepitus

Sternum crepitus is most commonly caused by sternal osteomyelitis, sternal fracture, post-sternotomy complications, or soft tissue infections with gas-forming organisms. 1, 2

Primary Causes

1. Sternal Osteomyelitis

• Primary sternal osteomyelitis (PSO) - a rare infection of the sternum without prior trauma or surgery 3
• Common causative organisms include:
  • Staphylococcus aureus (most common) 3
  • Streptococcus pneumoniae 4
  • Candida albicans 4
  • Peptostreptococcus species (rare) 5
• Presents with chest pain, fever, and crepitus on examination 3
• Risk factors include immunodeficiency, diabetes, and intravenous drug use 2

2. Post-Sternotomy Complications

• Sternal wound infections following cardiac surgery 1
• Sternal dehiscence or nonunion (sternal gap >3mm correlates with higher chest pain intensity) 1
• Mediastinitis - deep sternal wound infection extending to mediastinum 1
• Sternal instability causing painful crepitus with movement 6

3. Sternal Fractures

• Traumatic fractures from blunt anterior chest wall trauma 6
• Pathologic fractures (e.g., from metastatic disease) 1
• Stress fractures (rare) 1
• Fracture healing complications causing persistent crepitus 6

4. Soft Tissue Infections with Gas Formation

• Necrotizing fasciitis involving the chest wall 1
• Gas-forming soft tissue infections in the absence of trauma or puncture wound (reliable indicator of infection) 1
• Subcutaneous emphysema from trauma or infection 1

5. Other Causes

• Costochondritis (inflammation of costal cartilages) 1
• Radiation-induced chest wall injury (following treatment for breast or lung cancer) 1
• Scapulothoracic crepitus (when the scapula moves against the thoracic wall) 7

Diagnostic Approach

• Radiographs are first-line imaging to detect soft tissue gas and bony abnormalities 1, 2
• CT is the most sensitive modality for detecting soft tissue gas and determining its extent and location 1
• MRI with contrast is preferred for suspected osteomyelitis 1, 2
• FDG-PET/CT can help differentiate between osteomyelitis and reactive inflammation 1
• Patterns of infection on imaging:
  • Sternal osteomyelitis: focal uptake extending to adjacent soft tissue or sternal wire uptake 1
  • Soft tissue gas: indicates infection in absence of trauma or puncture wound 1

Clinical Pearls and Pitfalls

• Crepitus in the absence of recent surgery, trauma, or puncture wound is a reliable indicator of infection 1
• Diffuse, homogeneous uptake confined to the sternum can persist for months to years after surgery without infection 1
• Gas in deep fascial planes is a hallmark of necrotizing fasciitis and requires urgent surgical intervention 1
• Sternal nonunion with a gap >3mm correlates with significantly higher chest pain intensity 1
• Fracture-related uptake on imaging usually normalizes within 3 months of trauma 1

Understanding the specific cause of sternum crepitus is crucial for appropriate management, as treatment approaches differ significantly between infectious, traumatic, and inflammatory etiologies.