Bone & joint infections Flashcards
How do bone infections spread?
- Haematogenous
- Direct inoculation
- Contiguous-focus: spread from adjacent area
What are the stages of bone infection
- 1= necrosis-medullary contents/endosteal surface, (haematogenous)
- 2=Superficial-necrosis limited to exposed surface (contiguous)
- 3=localised-full thickness cortical sequestration stable before & after debridement
- 4=Diffuse- extensive, unstable bone
What is the clinical presentation of osteomyelitis?
- Pain
- Soft tissue swelling
- Erythema
- Warmth
- Localised tenderness
- Reduced movement
- Systemic: fever, chills, night sweats
What are causes of osteomyelitis?
- Staph aureus
- Strep group A&B
- Enterococci
- Anaerobes
- Gram negative bacilli (salmonella, Klebsiella, pseudomonas)
- Mycobacterium-TB, brucella
How is osteomyelitis diagnosed?
- Blood Cultures
- Histology of bone biopsy/needle aspirate
- Leukocytosis
- C-reactive protein
- Superficial swabs
How is osteomyelitis treated?
- IV antimicrobials (avoid empirical)
- Surgery depending on stage
- Clindamycin, vancomycin, ciprofloxacin, gentamicin, ß-lactams
- Flucloxacilin IV against staph aureus
What is septic/infective arthritis?
Inflammatory reaction in joint space caused by infection from direct invasion
What are the types of direct spread?
- Native (natural)
- Prosthetic (artificial)
What is the pathogenesis of native joint infection?
- Organism enters joint via blood/trauma
- Synovial tissue highly vascularised lacks basement membrane
- Cartilage erosion causes joint space narrowing/impaired function
What are predisposing factors of native joint infection?
- RA
- trauma
- IV drug use
- Immunosuppressive disease
What is the pathogenesis of prosthetic joint infection?
- Organism enters joint via blood/trauma
- Joint prosthesis & cement provide surface for bacterial attachment
- Polymorph infiltration= tissue damage instability of prosthesis
What are predisposing factors of prosthetic joint infection?
- Prior surgery at site of prosthesis
- Obesity
- RA
- Corticosteroid therapy
- Diabetes
- Poor nutritional state
- Extreme age
What is the clinical presentation of septic arthritis?
- Joints pain, swelling, tenderness, redness, limited movement
- Fever, chills, night sweats
- Duration variable & influenced by site of infection
What organisms cause septic arthritis?
- Bacteria
- Fungi= candida
- Viruses cause self-limiting arthritis (mumps, parvovirus B19, rubella)
What are the main organisms that cause native joint infection?
- Haem influenzae
- Neisseria meningitidis
- Neisseria gonorrhoeae
