Septic arthritis

  • Definition
  • Alternative Names
    • Bacterial arthritis; Non-gonococcal bacterial arthritis

  • Causes
    • Septic arthritis develops when bacteria or other tiny disease-causing organisms (microorganisms) spread through the blood to a joint. It may also occur when the joint is directly infected with a microorganism from an injury or during surgery. Joints that are commonly affected are the knee and hip. 

      Most cases of acute septic arthritis are caused by Staphylococcus or Streptococcus bacteria.

      Chronic septic arthritis (which is less common) is caused by organisms including Mycobacterium tuberculosis and Candida albicans.

      The following conditions increase your risk for septic arthritis:

      • Artificial joint implants
      • Bacterial infection somewhere else in your body
      • Presence of bacteria in your blood
      • Chronic illness or disease (such as diabetes, rheumatoid arthritis, and sickle cell disease)
      • Intravenous (IV) or injection drug use
      • Medicines that suppress your immune system
      • Recent joint injury
      • Recent joint arthroscopy or other surgery

      Septic arthritis may be seen at any age. In children, it occurs most often in those younger than 3 years. The hip is often the site of infection in infants. Most cases are caused by the bacteria group B streptococcus. Another common cause is Haemophilus influenza, especially if the child has not been vaccinated for this bacteria.

  • Symptoms
    • Symptoms usually come on quickly. There is a fever and joint swelling that is usually in just one joint. There is also intense joint pain, which gets worse with movement.

      Symptoms in newborns or infants:

      • Crying when infected joint is moved (for example, during diaper change)
      • Fever
      • Not able to move the limb with the infected joint (pseudoparalysis)
      • Fussiness

      Symptoms in children and adults:

      • Not able to move the limb with the infected joint (pseudoparalysis)
      • Severe joint pain
      • Joint swelling
      • Joint redness
      • Fever

      Chills may occur, but are uncommon.

  • Exams and Tests
  • Treatment
    • Antibiotics are used to treat the infection.

      Resting, raising the joint above heart level, and using cool compresses may help relieve pain. After the joint starts to heal, exercising it can help speed recovery.

      If joint (synovial) fluid builds up quickly due to the infection, a needle may be inserted into the joint often to aspirate the fluid. Severe cases may need surgery to drain the infected joint fluid.

  • Outlook (Prognosis)
    • Recovery is good with prompt antibiotic treatment. If treatment is delayed, permanent joint damage may result.

  • When to Contact a Medical Professional
    • Call for an appointment with your provider if you develop symptoms of septic arthritis.

  • Prevention
    • Preventive (prophylactic) antibiotics may be helpful for people at high risk.

  • References
    • Cook PP, Siraj DS. Bacterial arthritis. In: Firestein GS, Budd RC, Gabriel SE, et al., eds. Kelly's Textbook of Rheumotology. 9th ed. Philadelphia, PA: Elsevier Saunders; 2013:chap 109.

      Krogstad P. Septic arthritis. In: Cherry JD, Harrison GJ, Kaplan SL, Steinbach WJ, Hotez PJ. Feigin and Cherry's Textbook of Pediatric Infectious Diseases. 7th ed. Philadelphia, PA: Elsevier Saunders; 2014:chap 56.