What are the signs and treatment of osteomyelitis in the sternum?

Signs and Treatment of Osteomyelitis in the Sternum

Sternal osteomyelitis requires prompt diagnosis and aggressive treatment with both surgical debridement and appropriate antibiotic therapy to prevent serious complications and reduce mortality.

Clinical Presentation

Signs and Symptoms

• Chest pain in the sternal region, often persistent and worsening over time 1, 2
• Fever, which may be present in infectious cases but absent in non-bacterial osteomyelitis 3, 1
• Erythema and swelling over the sternum 4, 2
• Purulent drainage or fistula formation in advanced cases 4, 2
• Systemic symptoms such as chills in cases of infectious osteomyelitis 3

Laboratory Findings

• Significantly elevated C-reactive protein (CRP) or erythrocyte sedimentation rate (ESR) 3
• Positive blood cultures (most commonly Staphylococcus aureus) 1
• Bacteremia may be present in infectious cases 3

Diagnostic Approach

Initial Imaging

• Plain radiographs should be performed first but may be normal in early disease 3
• Radiographic findings may include bone sclerosis and areas of destruction in more chronic cases 3
• Progressive changes on serial plain radiographs may help in chronic cases 3

Advanced Imaging

• MRI is the preferred imaging modality with highest sensitivity and specificity for osteomyelitis 3
  • Key findings include bone marrow edema, soft tissue involvement, and enhancement after contrast administration 3, 2
  • A negative MRI effectively excludes osteomyelitis 3
• CT scan can show osteolytic lesions, periosteal reaction, trabecular coarsening, and fistulae 3, 4
• Nuclear medicine studies (bone scans, WBC scans) may be useful when MRI is contraindicated 3
  • FDG-PET/CT shows high sensitivity (85-94%) and specificity (78-93%) for osteomyelitis 3

Definitive Diagnosis

• Bone biopsy with culture and histopathological examination is the gold standard for diagnosis 3
• Samples should be obtained before initiating antibiotic therapy whenever possible 3
• PCR testing may be valuable for identifying specific pathogens like Mycobacterium tuberculosis 4

Differential Diagnosis

Key Conditions to Consider

• Infectious osteomyelitis (bacterial, fungal, or mycobacterial) 3
• Chronic non-bacterial osteitis (CNO) 3
• Malignant bone tumors 3
• Tietze's syndrome (costochondritis) 3, 2
• Anterior sternoclavicular subluxation 3
• Post-sternotomy complications in patients with prior cardiac surgery 3
• SAPHO syndrome (synovitis, acne, pustulosis, hyperostosis, osteitis) 5

Treatment Approach

Antimicrobial Therapy

• Initial parenteral antibiotics targeting the most likely pathogens (especially S. aureus) 3, 1
• Duration of therapy:
  • 2-4 weeks for soft tissue infection only 3
  • 4-6 weeks for confirmed osteomyelitis 3, 6
  • Up to 3 months for chronic cases 3
• Switch to oral antibiotics with good bioavailability (fluoroquinolones, clindamycin, linezolid) after initial parenteral therapy 3, 6

Surgical Management

• Surgical debridement is essential for treatment success in most cases 6
• Indications for surgical intervention include:
  • Substantial bone necrosis or exposed joint 3
  • Presence of abscess formation 2
  • Failure to respond to antibiotic therapy 3
  • Infected hardware or foreign bodies 3
• Surgical options include:
  • Debridement alone 6
  • Debridement with muscle flap coverage for larger defects 6
  • Partial or complete sternectomy in severe cases 2

Treatment Outcomes

• Operated patients have significantly fewer relapses compared to those treated with antibiotics alone 6
• Complete resolution of infection can be achieved with appropriate combined surgical and antimicrobial therapy 1, 2
• Monitoring for treatment response should include clinical assessment and trending of inflammatory markers 6

Special Considerations

Post-Surgical Sternal Osteomyelitis

• More common than primary sternal osteomyelitis 3
• CT has variable performance in diagnosis of sternal wound infections after cardiac surgery 3
• CT sensitivity and specificity improve beyond 17 days post-surgery (100% and 90%, respectively) 3

Primary Sternal Osteomyelitis

• Rare condition that may develop without any contiguous focus of infection 1
• Often misdiagnosed initially as non-cardiogenic chest pain 1
• May require more extensive workup to rule out other causes of chest pain 1

Mycobacterial Sternal Osteomyelitis

• Consider in patients with persistent symptoms despite standard antibiotic therapy 4
• PCR testing of biopsy specimens may be necessary for diagnosis 4
• Requires specialized antimicrobial regimens and longer treatment duration 3, 4