Septic Arthritis

What is Septic Arthritis?

Septic arthritis involves an infection in a joint. The most affected joints in children are the hips, knees and ankles.

Children with septic arthritis usually become unwell quickly. They will present with symptoms including:

  • A fever – with a temperature over 38° C
  • A hot, swollen, red joint
  • A painful joint which is uncomfortable to move
  • Limp or refusal to weight bear through the affected limb
  • Reduced joint range of movement
  • Tenderness of structures surrounding the affected joint

Babies with septic arthritis will often be irritable and have a fever. Most commonly the hip is affected, and the baby may become particularly irritable at nappy changes when the hip is being moved. The baby may tend to hold their leg in an unusual posture.

Who gets it?

Septic arthritis occurs most commonly in the first few years of life with up to 50% of cases occurring before the age of 2. It is relatively rare and affects 4-5 per 100,000 children each year.

It affects males more than females (2:1). In 35% of cases a hip joint is involved, and another 35% of cases will affect a knee joint.

Babies most at risk of developing septic arthritis are babies born prematurely, babies  born via a caesarean section and babies who have spent time in neonatal intensive care units. Children that have undergone invasive medical procedures are also more at risk of septic arthritis.

Septic arthritis is usually caused by bacteria travelling in a child’s blood stream to a joint or following an infection in a surrounding bone. It may also be caused from a penetrating injury into a joint. However, often the cause is unknown.

What is the natural history of Septic Arthritis?

Septic arthritis is a condition that requires specialist care in a hospital. With early diagnosis and specialist treatment the outcomes are very good and most cases of septic arthritis will not result with any long term damage to the affected joint.

What is the treatment?

If you think that your child may have septic arthritis, you should take them to an emergency department. The treating doctor will need to arrange for some tests to be taken to make a diagnosis of septic arthritis.

Children with septic arthritis will need to be admitted to hospital for treatment. This will involve:

  • Antibiotics (intravenously)
  • Pain relief medicine
  • A surgical procedure to wash out the joint and clean out the infection. This will be done with the child asleep (under a General Anaesthetic – GA). This procedure may need to be done on more than one occasion.
  • Gentle traction, a splint or cast may be applied to stop the affected  joint from moving and to make the child more comfortable

While in hospital a child with septic arthritis will have their temperature monitored closely as well as regular blood tests to monitor their progress and recovery.

Antibiotic medicine will be required in hospital and may need to be continued at home. If IV antibiotics are required at home, a nurse will visit the home to assist with this. Oral antibiotics – (liquid or tablets) may also be required for another three to six weeks after discharge from the hospital.

Children can usually be discharged home from hospital once their temperature has remained normal for 24 hours. Recovery time and hospital stay for each child will vary.

What tests are required?

A range of tests are usually required, these will include x-ray, ultrasound and blood tests.

What follow up is required?

Regular follow up appointments are important and necessary to check that the affected joint continues to grow and develop appropriately. Blood tests may be required in preparation for these appointments.