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Infection

Septic arthritis - presentation and management

Joint infection: organisms, presentation, aspiration and drainage, antibiotics.

8 questions 1 source pages 1 fact-check flags

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8 questions
Q1What is the differential diagnosis of unilateral hip pain in a child?▸
  • Transient synovitis / osteomyelitis
  • Septic arthritis
  • Perthes disease
  • SCFE
  • Fracture (consider NAI)
  • JRA
Q2What are the causes and risk factors for septic arthritis of the hip in a child?▸
  • Routes: haematological spread, direct inoculation, spread from osteomyelitis
  • Neonate with patent transphyseal artery, or the 4 intracapsular physes: proximal humerus, hip, radial head, distal fibula
  • Risk factors: prematurity, C-section (C section), history of invasive trauma
  • Recent infection (URTI, UTI); vaccine (especially H influenzae)
Q3Describe the pathoanatomy of septic arthritis.▸
  • Metaphyseal collection from transphyseal vessel: low flow sharp-turn capillary ruptures and spreads to the joint
  • Synovial oedema and hypertrophy with fluid production
  • Frank pus destroys cartilage within 8hr (marginal and central portions) with joint space narrowing
  • Superficial marginal and central bony erosion, then bony ankylosis (chronic)
Q4Describe the Gachter classification of septic arthritis.▸
  • 1. Synovitis
  • 2. Pus
  • 3. Cartilage
  • 4. Bone erosion
Q5Why is knee septic arthritis uncommon?▸
  • The metaphyseal collection from the transphyseal vessel spreads to the joint only in intra-articular metaphyseal joints
  • The knee is not an intra-articular metaphyseal joint, so knee septic arthritis is uncommon
Q6What are the Kocher criteria and the probability of septic arthritis for each score?▸
  • Unable to bear weight; fever >38.5; WBC >12; ESR >40
  • 1 criterion: 3%; 2: 40%; 3: 93%; 4: 99.6%
  • Caird modification (2006 JBJS): CRP >20
Q7How is septic arthritis of the hip managed?▸
  • History of trauma, onset and duration of pain, constitutional symptoms; check skin for sinus and whether the child can weight bear
  • X-ray to rule out SCFE, Perthes, fracture; blood WBC, CRP, ESR; USG for effusion and aspiration
  • Drainage: open anterior hip approach, capsulectomy 1cm2, drill holes at metaphysis, thorough irrigation
  • Post-op hip spica for 4-6 weeks
  • Peltola NEJM 2014: a few days IV (3-5) then a short course of oral antibiotics (3 weeks)
Q8How are the sequelae of septic arthritis of the hip classified and treated (Hunka classification)?▸
  • I minimal collapse/deformity
  • II head deformity (A intact physis, B physeal arrest) -> femoral osteotomy
  • III pseudoarthrosis -> head viable: BG + valgus osteotomy; head nonviable: resection of head and neck + GT arthroplasty
  • IV complete epiphysis destruction (A neck in acetabulum: adductor tenotomy, B neck not in acetabulum: GT arthroplasty)
  • V complete head and neck loss -> conservative

Fact check

Peltola NEJM 2014 showed that only a few days of IV (3-5) then a short course of oral antibiotics (3 weeks) is sufficient for uncomplicated joint sepsis — misattributed and imprecise — The NEJM 2014 Peltola paper is a review of acute osteomyelitis; the septic arthritis RCT (Clin Infect Dis 2009) showed 10 days total therapy (2-4 days IV then oral) was as effective as 30 days — source
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