Points to Ponder for NEET-PG, FMGE & NEXT
- Septic arthritis is a medical emergency requiring prompt diagnosis and treatment.
- Hematogenous spread is the most common route of infection, with Staphylococcus aureus as the leading culprit.
- Joint aspiration is the gold standard for diagnosis.
- Early diagnosis and treatment are crucial to prevent permanent joint damage.
- Non-operative treatment is not an option due to the rapid cartilage destruction in septic arthritis.
- Be aware of joint-specific presentations, especially the characteristic “Tom-Smith position” for septic arthritis of the hip in infants.
Etiology
- Hematogenous spread: Most common route in all age groups
- Staphylococcus aureus: Most common organism
- Other bacteria: Streptococcus, gram-negative bacilli (especially in neonates and immunocompromised)
Clinical Presentation
- Acute onset of joint pain and swelling:
- Reduced range of motion: Absent movement in children suggests septic arthritis until proven otherwise.
- Joint warmth and redness (may be absent in early stages)
- Fever (may be absent in elderly or immunocompromised)
Joint-Specific Presentations
- Knee: Most commonly affected joint often presents in flexion.
- Hip (especially in infants): Presents in flexion, abduction, and external rotation (often called “Tom-Smith position”). May progress rapidly to chondrolysis (destruction of the femoral head- femoral capital epiphysis) leading to:
- Limp
- Unstable gait
- Shortening of the affected limb
- Increased hip movement in all directions (due to joint laxity)
Diagnosis
- Imaging:
- X-rays: Usually normal in early stages, may show joint effusion later.
- MRI: May show joint effusion, synovitis, or cartilage destruction (more sensitive than X-ray).
- Joint fluid aspiration: Gold standard for diagnosis
- Helps differentiate from transient synovitis
- Performed after X-ray and MRI (if indicated) to avoid introducing infection
Treatment
- Antibiotics: Prompt and appropriate antibiotic therapy is crucial.
- Surgical drainage: Arthrotomy (opening the joint capsule) and surgical drainage (decompression) are essential to remove pus and prevent joint destruction.
- Synovectomy (removal of inflamed synovial tissue): May be performed in some cases.
- Non-operative management is contraindicated: Cartilage destruction can occur rapidly in septic arthritis, causing permanent joint damage.
