Large JPG-Aro Ha_0380.jpg

  • the most frequent bacteria is staphylococcus aureus

  • cartilage damage can occur by 8 hours

  • most commonly affected joints in descending order

    • knee (~ 50% of cases) >

    • hip >

    • shoulder >

    • elbow  >

    • ankle >

    • sternoclavicular joint 

      • found in IV drug users

      • pseudomonas aeruginosa was most common pathogen in 1980's

      • staphylococcus aureus is now the most common pathogen in all patients, including IV drug users

  • risk factors

    • age > 80 years

    • medical conditions

      • diabetes

      • rheumatoid arthritis

      • cirrhosis

      • HIV

    • history of crystal arthropathy

    • endocarditis or recent bacteremia

    • IV drug user

    • recent joint surgery

 

Symptoms

  • pain in affected joint

  • fevers (only present in 60% of cases)

  • may appear toxic

  • Inability to bear weight

  • inability to tolerate PROM 

3 etiologies of bacterial seeding of joint

  • bacteremia

  • direct inoculation from trauma or surgery

  • contiguous spread from adjacent osteomyelitis

Blood test :

  • WBC >10000

  • ESR >30

  • CRP > 5

Septic-Arthritis.jpeg

Characteristic findings

  • joint fluid appears cloudy or purulent

  • cell count with WBC > 50,000 is considered diagnostic for septic arthritis, however lower counts may still indicate infection

    • prosthetic joint with WBC >1,100 is considered septic

  • gram stains only identifies infective organism 1/3 of time

  • glucose less than 60% of serum leve

Joint fluid aspirate 

  • gold standard for treatment and allows directed antibiotic treatment

  • should be analyzed for

    • cell count with differential 

    • gram stain

    • culture

    • glucose level

    • crystal analysis

      • septic arthritis occurs concurrently with gout or pseudogout in < 5% of cases

synovial fluid.jpg

  • Differential diagnosis

  • Crystal arthropathy

    • gout 

    • pseudogout 

  • Cellulitis

  • Bursitis

treatment: ATB + lavage