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Septic arthritis is an infection in a joint. It is most commonly a bacterial infection. Joints affected are usually leg joints such as hips, knees and ankles.
Septic arthritis is usually caused by bacteria entering the joint through the bloodstream, or following infection of a surrounding bone. Occasionally it can follow a penetrating injury (where skin was broken), but often the cause is unknown. In rare cases septic arthritis can be caused by a
The infection causes the build-up of pus within the joint, which makes the joint swollen and painful.
The symptoms of septic arthritis can vary. If your child has septic arthritis, they will usually become unwell rapidly. They may be generally unwell, and have:
In newborns and young babies, the only obvious symptoms of septic arthritis may be irritability or fever. Commonly the hip is affected, and your baby may have swelling in the buttock or thigh, an inability to move the hip (especially during nappy changes) and they may hold their leg in an
Pain and decreased movement in the hip are also signs of another common condition called transient synovitis (also known as irritable hip). See our fact sheet
Transient synovitis (irritable hip).
A condition with similar symptoms affecting bones is osteomyelitis. See our fact sheet
If you think your child has septic arthritis, you should take your child to the nearest emergency department. The doctor will make a diagnosis by looking at and assessing the joint, and asking questions about your child's symptoms and recent history (e.g. recent injury to the area, if
they have had other infections). Your child will usually also need an X-ray, ultrasound, and some blood tests.
If your child has recently had an injury and they are showing signs of septic arthritis in the injured area, return to your treating hospital.
The IV antibiotic treatment will continue until your child shows signs of improvement, through their blood tests and temperature checks. In some cases, long-term IV antibiotics can be given after your child has gone home from hospital, with nurses visiting you at home to help. Your child may
need to keep taking oral (by mouth) antibiotic liquid or tablets for another three to six weeks.
Each child recovers at a different speed. It is difficult to know how long they will need to stay in hospital, but most children will be able to go home once their temperature has been normal for 24 hours.
It is very important to make sure your child keeps taking every dose of their oral antibiotics. This will ensure they recover from the infection, and prevent the infection from coming back. Your child must take the entire course of antibiotics.
Keep an eye out for an increase in your child's temperature or any of the other signs and symptoms listed above. If any of these symptoms develop, go to the hospital emergency department or contact your treating doctor.
Your child will have a follow-up appointment after they leave hospital. It is important to keep this appointment, even if your child seems well. Regular follow-up will be arranged to ensure that there has not been any damage to the joint. Blood tests may also be arranged, which
should be performed prior to your child's appointment.
Will my child's joint recover completely? Will they be at
risk of arthritis in that joint when they are older?
If treated early, almost all cases of septic arthritis do
not result in long-term damage to the joint or surrounding bones. It is
therefore important that the condition is diagnosed quickly and treated
Why do I need to complete the antibiotics if my child's
infection is all better?
Not completing a full course of antibiotics may
lead to the bacteria becoming resistant to the antibiotic that was prescribed
to treat your child. This means that stronger antibiotics may be required, and
contributes to worldwide antibiotic resistance. It is important to ensure that
all of the bacteria have been killed off, which is why the course continues for
many days after your child looks and feels better.
Developed by The Royal Children's Hospital Orthopaedic department. We acknowledge the input of RCH consumers and carers.
Reviewed June 2018.
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