Osteomyelitis Overview and Risk Factors

Osteomyelitis Definition and Incidence

• Osteomyelitis is a pyogenic bone infection of surrounding tissues, either acute or chronic, needing immediate intervention.
• It occurs at any age but is more common under 12.
• Males are affected more often than females due to higher rates of blunt trauma.

Etiology and Risk Factors

• Common causes are bacterial infections, primarily Staphylococcus aureus. Other bacteria like Escherichia coli, Pseudomonas, Klebsiella, and Proteus can also be involved.
• Viral and fungal organisms can also initiate osteomyelitis.
• Infection routes include:
  • Direct: Open fractures, surgeries, open wounds.
  • Hematogenous: Spread from other sites (e.g., upper respiratory infection, tonsillitis, genitourinary tract infections, infected teeth)
• Risk factors include:
  • Malnutrition
  • Old age
  • Obesity
  • Weakened immune system
  • Chronic diseases (rheumatoid arthritis, diabetes)
  • Long-term corticosteroid use

Types of Osteomyelitis

• Acute osteomyelitis: Infection lasting less than one month.
• Chronic osteomyelitis: Infection lasting more than four weeks that doesn't respond to initial antibiotic treatment.

Pathophysiology

• Initial response: Inflammation, increased blood flow, and swelling.
• 2-3 days: Ischemia (reduced blood flow) and bone tissue necrosis (death)
• Infection spreads to the medullary cavity, periosteum, and surrounding soft tissues and joints.
• Chronic osteomyelitis development: If infection isn't effectively treated.
• Abscess formation: Containing dead bone (sequestrum), which is slow to liquefy and drain.
• New bone growth: Develops around the sequestrum, but the infected area persists, leading to recurring abscesses.

Clinical Manifestations

• General symptoms: High fever (38.5-40°C), chills, tachycardia, malaise, headache, nausea.
• Local symptoms (acute): Localized pain (worsening with movement), tenderness, redness, warmth, swelling.
• Local symptoms (chronic): Recurrent pain, redness, warmth, swelling, draining sinus tracts, low-grade fever (up to 38°C).

Complications

• Acute osteomyelitis can progress to chronic form with ineffective treatment.
• Growth retardation in children.
• Septic arthritis and osteoarthritis (infection spreading to adjacent joints).
• Septicemia (infection spreading to the bloodstream).
• Squamous cell carcinoma development (in cases of chronic, draining sinuses).

Diagnostic Studies

• Laboratory tests: Complete blood count (elevated white blood cells), elevated erythrocyte sedimentation rate (ESR). Blood and wound cultures (to identify the causative organism).
• Radiological studies: Bone X-rays (initial soft tissue swelling, bone necrosis), bone scans (detect inflammation), MRI (soft tissue mass, sinus tracts, bone marrow changes).

Management

• General management: Immobilization of the affected area (e.g., casts, slings), pain management, fever control, aseptic wound care.
• Pharmacological management:
  • IV antibiotics (e.g., semisynthetic penicillins, cephalosporins, tetracyclines, aminoglycosides) until controlled, then oral for up to 3 months.
  • Analgesics (pain relievers) and antipyretics (fever reducers).
  • Hyperbaric oxygen therapy (100% O2 at 2 ATM for 2 hours, 6 times/week).
• Surgical management (acute): Needle aspiration, percutaneous biopsy.
• Surgical management (chronic): Surgical debridement to remove dead bone and infected tissue.