Septic Arthritis in Children
Septic Arthritis in Children
Definition and Overview
Septic arthritis is an acute infectious inflammation of the joint space that represents a medical emergency in pediatric population. The condition primarily affects children under 3 years of age and can lead to permanent joint damage if not treated promptly.
Key Points
- Most common in children under 3 years
- Hip and knee joints most frequently affected
- S. aureus is the predominant causative organism
- Requires urgent treatment to prevent joint destruction
- Higher incidence in immunocompromised children
Associated Syndromes
- Chronic Granulomatous Disease
- Primary Immunodeficiencies
- Sickle Cell Disease
- Job's Syndrome
Pathophysiology and Etiology
Pathogenic Mechanisms
- Hematogenous spread (most common)
- Direct inoculation
- Contiguous spread from adjacent infection
Causative Organisms
Age-specific pathogens:
- Neonates (0-2 months):
- Staphylococcus aureus
- Group B Streptococcus
- Gram-negative organisms
- Infants and Children (2 months-5 years):
- Staphylococcus aureus (including MRSA)
- Streptococcus pyogenes
- Kingella kingae
- Older Children (>5 years):
- Staphylococcus aureus
- Neisseria gonorrhoeae (sexually active adolescents)
Risk Factors
- Recent trauma
- Immunodeficiency
- Hemoglobinopathies
- Previous joint surgery
- Adjacent soft tissue infection
- Bacteremia
Clinical Features
Cardinal Signs
- Acute onset joint pain
- Limited range of motion
- Joint swelling and erythema
- Fever (>38.5°C)
- Refusal to bear weight/use affected limb
- Pseudoparalysis in infants
Joint Distribution
Frequency of affected joints:
- Hip (45%)
- Knee (35%)
- Ankle (15%)
- Elbow (5%)
- Other joints (<1%)
Age-Specific Presentations
- Neonates:
- Irritability
- Poor feeding
- Pseudoparalysis
- Minimal systemic symptoms
- Older Infants/Children:
- More localized symptoms
- Refusal to bear weight
- Clear joint pain
Diagnosis
Laboratory Studies
- Blood Tests:
- Complete Blood Count (CBC)
- ESR (typically >40 mm/hr)
- CRP (>20 mg/L)
- Blood Cultures (positive in 40-50%)
- Synovial Fluid Analysis:
- WBC >50,000/mm³
- PMN >75%
- Gram stain
- Culture and sensitivity
Imaging Studies
- Plain Radiographs:
- Joint space widening
- Soft tissue swelling
- Displacement of fat pads
- Ultrasound:
- Joint effusion
- Synovial thickening
- Guide for aspiration
- MRI:
- Early changes
- Extent of infection
- Associated osteomyelitis
Treatment
Emergency Management
- Joint aspiration
- Empiric antibiotics
- Joint drainage
- Pain management
- Joint immobilization
Surgical Intervention
- Indications:
- Hip joint involvement
- Inadequate aspiration
- Failed medical management
- Presence of complications
- Procedures:
- Arthrotomy
- Arthroscopic lavage
- Repeat drainage if needed
Antibiotic Therapy
- Initial Empiric Therapy:
- 0-2 months: Vancomycin + Gentamicin
- 2 months-5 years: Cefazolin or Clindamycin
- >5 years: Anti-staphylococcal penicillin or Cefazolin
- Duration:
- Minimum 2-3 weeks IV
- Total 3-4 weeks based on response
Complications and Prognosis
Early Complications
- Osteomyelitis
- Sepsis
- Adjacent soft tissue abscess
- DVT
Late Complications
- Growth disturbance
- Chronic arthritis
- Joint deformity
- Limb length discrepancy
- Avascular necrosis (especially in hip)
Prognostic Factors
- Good Prognosis:
- Early diagnosis (<4 days)
- Prompt treatment
- Non-hip joint involvement
- Age >6 months
- Poor Prognosis:
- Delayed treatment (>4 days)
- Hip joint involvement
- Age <6 months
- MRSA infection
Disclaimer
The notes provided on Pediatime are generated from online resources and AI sources and have been carefully checked for accuracy. However, these notes are not intended to replace standard textbooks. They are designed to serve as a quick review and revision tool for medical students and professionals, and to aid in theory exam preparation. For comprehensive learning, please refer to recommended textbooks and guidelines.
