Osteomyelitis

Osteomyelitis is a serious bone infection that can be acute or chronic, affecting people of all ages. The infection can reach bones through the bloodstream, from nearby tissues, or directly through wounds. While once considered difficult to treat, modern antibiotic therapy and surgical techniques have significantly improved outcomes. Early diagnosis and aggressive treatment are crucial to prevent complications such as bone death, sepsis, and chronic infection.

⚠️ Seek Immediate Medical Care

Seek emergency care for: high fever with bone pain, severe pain in a limb with swelling/redness, drainage from a wound near bone, inability to move affected area, or signs of sepsis (confusion, rapid breathing, low blood pressure). Untreated osteomyelitis can lead to permanent bone damage or life-threatening sepsis.

Medical Disclaimer: This information is for educational purposes only and should not replace professional medical advice. Always consult with a qualified healthcare provider for diagnosis and treatment of any medical condition.

Understanding Osteomyelitis

Osteomyelitis occurs when bacteria or fungi invade bone tissue, causing inflammation and destruction. The infection can develop rapidly (acute) or persist over months to years (chronic). Without proper treatment, the infection can spread, destroy bone tissue, and lead to serious complications.

Classification

  • By Duration:
    • Acute: Develops within 2 weeks, rapid onset
    • Subacute: 2 weeks to 3 months
    • Chronic: Persists longer than 3 months
  • By Source:
    • Hematogenous: Spread through bloodstream (20-30%)
    • Contiguous spread: From adjacent soft tissue infection
    • Direct inoculation: Trauma, surgery, or puncture wounds
  • By Host Status:
    • Normal host
    • Compromised host (diabetes, immunosuppression)

Pathophysiology

  • Bacteria enter bone through various routes
  • Inflammatory response causes increased pressure
  • Pus formation compresses blood vessels
  • Ischemia leads to bone necrosis (sequestrum)
  • New bone forms around dead bone (involucrum)
  • Biofilm formation makes treatment difficult

Types of Osteomyelitis

Acute Hematogenous Osteomyelitis

  • Most common in children
  • Bacteria spread through bloodstream
  • Usually affects long bone metaphysis
  • Common sites: femur, tibia, humerus
  • Rapid onset with systemic symptoms

Vertebral Osteomyelitis

  • Most common in adults >50 years
  • Usually hematogenous spread
  • Lumbar spine most affected
  • Can cause spinal instability
  • Risk of epidural abscess

Chronic Osteomyelitis

  • Results from inadequately treated acute infection
  • Presence of dead bone (sequestrum)
  • Draining sinus tracts common
  • Biofilm formation
  • Requires prolonged treatment

Diabetic Foot Osteomyelitis

  • Common complication of diabetic foot ulcers
  • Often polymicrobial
  • Poor healing due to vascular disease
  • High risk of amputation
  • Requires multidisciplinary approach

Prosthetic Joint Infection

  • Infection around artificial joints
  • Early (<3 months) vs late presentation
  • Biofilm on prosthesis
  • Often requires prosthesis removal
  • Two-stage revision common

Causes and Risk Factors

Common Pathogens

  • Staphylococcus aureus:
    • Most common cause (50-70%)
    • Including MRSA
    • All age groups
  • Streptococcus species:
    • Group A and B streptococci
    • Often in children
  • Gram-negative bacteria:
    • E. coli, Pseudomonas
    • Immunocompromised patients
    • Healthcare-associated
  • Anaerobes:
    • Diabetic foot infections
    • Bite wounds
  • Mycobacteria:
    • Tuberculosis (Pott's disease)
    • Immunocompromised patients
  • Fungi:
    • Candida, Aspergillus
    • Immunocompromised hosts

Risk Factors

Medical Conditions:

  • Diabetes mellitus
  • Peripheral vascular disease
  • Sickle cell disease
  • HIV/AIDS
  • Chronic kidney disease
  • Rheumatoid arthritis
  • Malnutrition

Medications/Treatments:

  • Immunosuppressive drugs
  • Chemotherapy
  • Chronic corticosteroids
  • Recent surgery
  • Radiation therapy

Lifestyle Factors:

  • Intravenous drug use
  • Alcoholism
  • Smoking
  • Poor hygiene

Other Risk Factors:

  • Recent trauma or fracture
  • Presence of foreign bodies
  • Pressure ulcers
  • Dental procedures
  • Hemodialysis

Signs and Symptoms

Acute Osteomyelitis

  • Local symptoms:
    • Severe bone pain
    • Tenderness over affected area
    • Swelling and warmth
    • Redness of overlying skin
    • Limited range of motion
    • Refusal to bear weight (children)
  • Systemic symptoms:
    • High fever and chills
    • Malaise and fatigue
    • Irritability (in children)
    • Poor feeding (infants)
    • Night sweats

Chronic Osteomyelitis

  • Persistent or intermittent pain
  • Draining sinus tract
  • Chronic wound that won't heal
  • Low-grade fever or no fever
  • Minimal systemic symptoms
  • Local swelling
  • Pathologic fracture

Vertebral Osteomyelitis

  • Back pain (gradual onset)
  • Pain worse at night
  • Fever in 50% of cases
  • Neurological symptoms if compression
  • Muscle spasms
  • Limited spinal mobility

Special Populations

Neonates and Infants:

  • May have minimal symptoms
  • Pseudoparalysis of affected limb
  • Irritability
  • Poor feeding
  • May lack fever

Diabetic Patients:

  • May have minimal pain (neuropathy)
  • Non-healing foot ulcer
  • Exposed bone (probe to bone test)
  • Minimal systemic symptoms

Diagnosis

Clinical Evaluation

  • Detailed history and physical exam
  • Assessment of risk factors
  • Probe to bone test for diabetic ulcers
  • Evaluation for source of infection

Laboratory Tests

  • Blood tests:
    • Elevated WBC count
    • Elevated ESR (>70 mm/hr suggestive)
    • Elevated CRP
    • Blood cultures (positive in 50%)
  • Bone biopsy:
    • Gold standard for diagnosis
    • Identifies causative organism
    • Guides antibiotic therapy
    • Distinguishes from tumor

Imaging Studies

  • Plain radiographs:
    • Initial imaging study
    • May be normal for 10-14 days
    • Shows bone destruction, periosteal reaction
    • Useful for follow-up
  • MRI (most sensitive):
    • Best for early detection
    • Shows bone marrow edema
    • Defines soft tissue involvement
    • Identifies abscesses
  • CT scan:
    • Better for cortical bone
    • Identifies sequestrum
    • Guides biopsy
    • Surgical planning
  • Bone scan:
    • High sensitivity
    • Low specificity
    • Useful for multifocal disease
  • PET scan:
    • Differentiates infection from tumor
    • Monitors treatment response

Treatment

Antibiotic Therapy

The cornerstone of osteomyelitis treatment is prolonged antibiotic therapy, ideally guided by culture results.

Empiric Therapy:

  • MSSA coverage: Nafcillin, oxacillin, or cefazolin
  • MRSA coverage: Vancomycin or daptomycin
  • Gram-negative coverage: Add ceftriaxone or fluoroquinolone
  • Anaerobic coverage: Add metronidazole if indicated

Duration:

  • Acute osteomyelitis: 4-6 weeks minimum
  • Chronic osteomyelitis: 3-6 months or longer
  • IV therapy: Usually 2-6 weeks, then oral
  • Biomarkers: Monitor ESR/CRP for response

Surgical Treatment

Indications for Surgery:

  • Abscess drainage
  • Debridement of necrotic tissue
  • Removal of sequestrum
  • Chronic osteomyelitis
  • Failed medical therapy
  • Spinal instability
  • Hardware removal if infected

Surgical Procedures:

  • Debridement:
    • Remove all dead bone
    • Obtain tissue cultures
    • May require multiple procedures
  • Bone grafting:
    • Fill defects after debridement
    • Promote healing
  • Muscle flaps:
    • Cover exposed bone
    • Improve blood supply
  • External fixation:
    • Stabilize bone
    • Allow access for wound care

Adjunctive Therapies

  • Hyperbaric oxygen:
    • Chronic refractory cases
    • Improves oxygen delivery
    • Enhances antibiotic efficacy
  • Antibiotic beads/spacers:
    • Local antibiotic delivery
    • Used in dead space
  • Negative pressure therapy:
    • Promotes wound healing
    • Reduces bacterial load

Comprehensive Management

Multidisciplinary Approach

  • Infectious disease specialist
  • Orthopedic surgeon
  • Vascular surgeon (if needed)
  • Wound care specialist
  • Physical therapist
  • Nutritionist

Monitoring Treatment

  • Clinical response:
    • Pain reduction
    • Decreased swelling
    • Improved function
    • Wound healing
  • Laboratory markers:
    • Weekly ESR/CRP initially
    • Should decrease by 1 month
    • Normal by end of treatment
  • Imaging:
    • Not routinely needed
    • May lag clinical improvement
    • MRI if not responding

Optimizing Outcomes

  • Nutritional support:
    • Adequate protein intake
    • Vitamin C and D
    • Zinc supplementation
  • Glycemic control:
    • Critical in diabetics
    • Target HbA1c <7%
  • Smoking cessation:
    • Improves healing
    • Reduces complications
  • Offloading:
    • Pressure relief
    • Appropriate footwear
    • Assistive devices

Complications

Local Complications

  • Chronic osteomyelitis: Failed initial treatment
  • Sequestrum formation: Dead bone acts as foreign body
  • Sinus tract: Chronic drainage
  • Pathologic fracture: Weakened bone breaks
  • Joint destruction: If extends to joint
  • Growth disturbance: In children

Systemic Complications

  • Sepsis: Life-threatening
  • Metastatic infection: Spread to other sites
  • Endocarditis: Heart valve infection
  • Amyloidosis: From chronic inflammation

Treatment Complications

  • Antibiotic resistance
  • Drug toxicity (kidney, hearing)
  • C. difficile colitis
  • Surgical complications
  • Non-union after surgery

Long-term Sequelae

  • Chronic pain
  • Limb length discrepancy
  • Decreased function
  • Need for amputation
  • Malignant transformation (rare)

Prevention

Primary Prevention

  • Prompt treatment of infections
  • Proper wound care
  • Good diabetic foot care
  • Vaccination (H. influenzae, pneumococcus)
  • Sterile surgical technique
  • Antibiotic prophylaxis when indicated

For High-Risk Patients

  • Regular foot exams for diabetics
  • Pressure ulcer prevention
  • Optimize chronic disease management
  • Avoid IV drug use
  • Dental hygiene
  • Early treatment of bacteremia

Prognosis

Factors Affecting Outcome

  • Early diagnosis and treatment
  • Causative organism
  • Location of infection
  • Patient's immune status
  • Presence of foreign material
  • Adequacy of surgical debridement

Expected Outcomes

  • Acute osteomyelitis:
    • 90-95% cure rate with early treatment
    • Lower in MRSA infections
  • Chronic osteomyelitis:
    • 30-50% recurrence rate
    • May require multiple surgeries
    • Long-term suppressive therapy sometimes needed
  • Vertebral osteomyelitis:
    • Good prognosis if no neurological deficit
    • 6-12 month recovery typical

With modern treatment approaches combining appropriate antibiotics and surgical intervention when necessary, most patients with osteomyelitis can achieve cure or long-term control of their infection. Early recognition and aggressive treatment remain key to preventing complications and achieving optimal outcomes.