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Lecture 8: septic arthritis and osteomyelitis - Coggle Diagram

- - - - Acute
        
        Causative agents
        
        S. aureus
        
        N.gonorrhoeae
        
        Acute gonococcal arthritis
        
        Young people
        
        Disseminated infection or arthritis
        
        Others (e.g. H. influenzae)
        
        Clinical clues
        
        Bites
        
        Human
        
        Cat
        
        Dog
        
        Tick
        
        Clinical features
        
        Fever
        
        Joint pain, swelling, erythema, heat
        
        Monoarticular (90% cases)
        
        Knee (usually)
    - - Prosthetic devices
        
        Biofilm related infections
        
        Prosthetic joint infections
        
        Pathophysiology
        
        Impaired blood supply
        
        Impaired innate immunity
        
        Bone necrosis
        
        Biofilm formation on device
        
        Aetiology
        
        Early onset (<3 months)
        
        S. aureus
        
        Delayed onset (3-24 months)
        
        Low virulence microorganisms (e.g. coagulase-negative Staphylococcus)
        
        Late onset (>24 months)
        
        Usually secondary to haematogenous spread
        
        Diagnosis
        
        Laboratory investigation
        
        WCC, ESR/CRP (elevated)
        
        Blood cultures
        
        Synovial fluid
        
        WCC, protein, glucose, lactate
        
        Gram statining, polarising microscopy
        
        Molecular methods (PCR)
        
        Treatment
        
        Quick diagnosis
        
        Antibiotics
        
        Joint drainage
        
        Removal of prosthetic device
- - - - Acute
      - Chronic
    - - Haematogenous
        
        Skeletal tuberculosis (Pott’s disease)
        
        Usually reactivation from previous haematogenous spread
        
        Axial skeleton (esp. thoracic), femur, tibia commonest sites
        
        Infection begins in anterior portion of vertebra
      - Contiguous focus
        
        Usually follows trauma, surgery, soft tissue infection or deep ulcers
        
        Often polymycrobial
    - - S. aureus (usually)
      - Pathogenesis
        
        Sequestra and infected bone
    - - Neuropathy
      - Angiopathy
      - Immune dysfunction
      - Small bones of feet most commonly involved
      - Usually polymicrobial in aetiology
      - Diagnosis and management often very difficult
      - Diagnosis
        
        Clinical features
        
        Laboratory diagnosis
        
        Imaging (X-ray, MRI)
      - Treatment
        
        Prolonged
        
        Antibiotics
        
        Surgical management
        
        Debridement / drainage
        
        Obliteration of dead space
        
        Wound protection with skin grafts or muscle flaps
      - Prevention
        
        Wound care
        
        Prevention of cross-transmission
        
        Hand hygiene