Septic Arthritis – Pathophysiology and Management

Septic arthritis is a severe, rapidly progressive infection affecting the synovial joints. It requires prompt diagnosis and aggressive treatment to prevent joint destruction and systemic complications.

Pathophysiology

Septic arthritis occurs when microorganisms—most commonly Staphylococcus aureus—penetrate the joint space via hematogenous spread, direct inoculation, or contiguous infection. The immune response leads to synovial inflammation, increased intra-articular pressure, and enzymatic cartilage degradation.

Risk Factors

• Underlying joint disease (e.g., rheumatoid arthritis, osteoarthritis)
• Immunosuppression (e.g., diabetes, HIV, malignancy)
• Recent joint surgery or invasive procedures
• IV drug use
• Prosthetic joint implants

Clinical Presentation

Patients with septic arthritis typically present with:

• Acute onset of severe joint pain
• Swelling, warmth, and erythema
• Restricted range of motion
• Fever and systemic symptoms

Diagnosis

Diagnostic confirmation involves:

• Joint Aspiration: Synovial fluid analysis showing high WBC count, low glucose, and positive culture
• Blood Tests: Elevated ESR and CRP
• Imaging: X-rays, ultrasound, and MRI for evaluation

Management

Treatment must be immediate and targeted:

• Empiric IV antibiotic therapy (based on gram stain and culture results)
• Joint drainage via arthrocentesis or surgical intervention
• Supportive care including analgesia and physical therapy

Prognosis

Early treatment significantly improves outcomes. Delayed intervention may result in irreversible joint damage or systemic complications.