Septic Arthritis

A type of arthritis resulting from infection of a joint

  • Most common in children and elderly people
  • Intravenous drug use is a risk factor
  • Gender and genetics are not significant factors

Septic arthritis is an infection in the synovial fluid or tissues of a joint, such as a hip or a knee. The condition is usually caused by bacteria that have entered the joint through a nearby open wound or have travelled through the bloodstream from an infection elsewhere in the body. For example, the bacteria that cause gonorrhoea may spread from the genital tract through the bloodstream. The risk of developing septic arthritis is increased in people who have rheumatoid arthritis, who have been fitted with an artificial joint, or who use intravenous recreational drugs.

What are the symptoms?

The symptoms of septic arthritis usually appear suddenly and may include:

  • Fever.

  • Swelling, tenderness, redness, and warmth around the affected joint.

  • Severe pain and restricted movement of the affected joint.

If pus builds up in an infected area, the joint may be damaged permanently. If you develop the above symptoms, consult your doctor immediately.

What might be done?

Your doctor may arrange for you to have a sample of fluid taken from the affected joint (see Joint aspiration). The fluid is analysed to look for evidence of infection and to try to establish its cause.

Septic arthritis caused by bacteria is initially treated with intravenous antibiotics for at least 4 weeks. Your doctor may then prescribe oral antibiotics for several weeks or months.

To help to relieve pain and inflammation, pus may be drained from the infected joint several times. Your doctor may also prescribe a nonsteroidal anti-inflammatory drug. You should rest the joint until the inflammation has completely subsided. Gentle movement is allowed and is important later on to prevent the joint becoming stiffened by shrinkage of the surrounding tissues. If the infected joint is an artificial joint, it may need to be replaced with a new one.

What is the prognosis?

If treatment is started early, the symptoms of septic arthritis should begin to subside within a few days, and eventually the inflammation may disappear completely. However, left untreated, the infection may be life-threatening and lead to irreversible joint damage.

From the 2010 revision of the Complete Home Medical Guide © Dorling Kindersley Limited.

The subjects, conditions and treatments covered in this encyclopaedia are for information only and may not be covered by your insurance product should you make a claim.

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