Septic arthritis (infectious arthritis) 3.5/5 (6)

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Septic Knee Arthritis, Caused by Tuberculosis: Lynn MM, 2012. Rheumatology Department, Queen Elisabeth Hospital, London, UK. CC BY 2.0


Septic arthritis is inflammation of the joints (Arthritis) caused by bacteria or other microorganisms. Infections of the vertebrae are termed Pyogen vertebral osteomyelitis.

Disease Cause

The most common thing about septic arthritis is that bacteria spread through the blood from another infection and migrate from the blood into one (less frequently more) joint. The Rarer requires bacteria from the skin, wounds or stings.

  • Risk Factors
    • Age over 65 years
    • Diabetes mellitus (diabetes)
    • Other rheumatic disease (at Arthritis, RA is the risk 4-15 doubled)
    • Skin infection
    • Intravenous substance abuse
    • venous Catheters
    • Liver disease
    • Surgical intervention
  • The most common cause is the bacterium Staphylococcus aureus (S. aureus) in Europe. Staphylococci have their own ability to infect joints. They can form one biofilm in the infected joint, making it difficult to get rid of the infection
  •  Rarer bacteria


The rate of septic arthritis (prevalence) is estimated at 4-10 / 100.000 in Western Europe (reference: Mathews CJ, 2010)


Knees are most commonly attacked (more than 50% of cases).

  • Hips, ankles, wrists are less frequently attacked
  • Pain, increased joint heat and swelling usually occur within a few hours and precede cartilage and bone damage


In about 50% the growth of bacteria in the blood is detected. Joint fluid and blood samples for the detection of bacteria are essential and should be sought before antibiotics are given.


Antibiotics, intravenously

  • Often the affected joint must be rinsed and drained repeatedly. This is usually done in the orthopedic department.

Incorrect diagnosis, Similar conditions, Differential diagnoses

Guidelines / recommendations

EULAR 2016 (Combe B, Management early arthritis)

ACR 2017 (Ringhold S, 2017; JIA and tuberculosis)

International 2014 (Inanone F, 2014)

Norwegian Rheumatological Association


More about Arthritis here (in Danish) (

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