What is septic arthritis?
Septic arthritis is extremely painful and can develop quickly. It’s a very serious condition which can affect people of any age. It needs to be treated in hospital as soon as possible as an emergency.
It’s most commonly caused by bacteria, from an infected cut or wound. The bacteria travels through the blood supply to a joint, which then becomes infected.
It can also be caused by a virus, skin infection or bacteria getting into your body through the site of an injection or surgery. It is sometimes called bacterial or infectious arthritis.
Any joint in the body can be affected by septic arthritis. It can affect more than one joint, though this is rare. It most commonly affects the knees and hips.
If you’re diagnosed with septic arthritis, the infection needs treating as soon as possible to prevent it causing long-term damage and other complications to your general health.
Your problems may be caused by septic arthritis if you’ve had a recent injury or wound, particularly if it’s become infected, and you find:
- you get sudden severe pain in one or more of your joints
- it’s difficult to move or put weight on the affected joint
- your joint is suddenly very sore and swollen
- the skin over your joints becomes red and hot
- you have a high temperature or fever
- you feel sick or can’t eat.
Children become irritable and may cry when the affected joint is moved. They may try to avoid moving it or may not be able to walk, particularly if it’s their hip that’s affected.
In most cases the symptoms develop within a few days.
However, the symptoms can be slower to develop after joint replacement surgery or if you have tuberculosis. At first, the pain and fever may be mild but will gradually get worse.
If you think you may have septic arthritis it’s important you see your GP or go to your nearest Accident and Emergency department (A&E) as soon as possible to stop the infection spreading and causing more damage.
Your chances of developing septic arthritis are increased if you have:
- a wound that becomes infected
- a joint injury.
Surgery or injections
- joint surgery, for example a hip or knee replacement
- an injection into or near a joint, such as a steroid injection
- injecting non-prescription drugs.
- the sexually transmitted infection (STI) gonorrhoeae, as it can infect your joints
- a urine infection
- food poisoning
- sinus or skin infections
- an infected sore throat
- an infection in your bones close to a joint.
A long-term condition
- rheumatoid arthritis or another inflammatory condition, which makes your joints more vulnerable to infection. If you feel your symptoms are worse than usual and you’re feeling unwell, see your doctor.
- conditions treated with drugs that reduce the activity of your immune system, for example immuno-suppressants used for arthritis or chemotherapy to treat cancer
- a poor or weakened immune system, caused by cancer, HIV or Aids
- another condition or serious illness that reduces your immune system’s ability to fight infection
- liver or kidney failure.
If your symptoms suggest you have septic arthritis, your GP will refer you immediately to your local Accident and Emergency department (A&E) for tests.
If you can’t get to see your doctor and you think you have septic arthritis, take yourself to your local A&E. The sooner it’s diagnosed, the better.
If there is a delay, the infection can quickly damage parts of the joint. This may lead to pain that lasts for a long time and loss of mobility.
In some cases, if left untreated, septic arthritis can lead to blood poisoning, known as septicaemia.
In hospital they will try to work out exactly what the infection in your joint is and how best to treat it. This will be done with a blood test.
You may also have a needle inserted into the joint, so a sample of the infected fluid can be tested. An x-ray or an MRI scan would give doctors a better picture of what is happening to the joint.
These tests may show that your inflammation has been caused by a different condition and that you don’t have septic arthritis.
Generally, if you have septic arthritis you’ll be kept in hospital, possibly for two weeks or more. During this time you’ll be given antibiotics directly into the vein (intravenously) to fight the infection.
You’ll be given painkillers too. For the first few days you may have to rest in bed to relieve the pressure on the affected joint.
You may also have fluid drained from the infected joints using a syringe and needle. This is called aspiration.
Sometimes the affected joint may need to be splinted after treatment, so the joint is supported and protected, as movement can be very painful at first.
You may be told you need a procedure called an arthroscopy. This is where a surgeon inserts a fine, metal tube into the affected joint.
If the infection is in a joint deep within your body, such as your hip, you may need open surgery to drain it.
If your septic arthritis affects an artificial joint it may have to be removed before the infection can be treated. Once the infection has gone, the joint can be replaced.
Once you’ve been discharged from hospital, you’ll probably be given a course of antibiotic tablets to clear up any remaining infection.
When the infection has been treated and your pain and inflammation have started to settle it’s important to begin moving your affected joint to prevent it becoming stiff.
How will septic arthritis affect me?
In most cases, early hospital treatment and antibiotics will successfully treat septic arthritis, leaving little or no lasting effects of the condition.
However, even after treatment, some people may still struggle to get full use out of the affected joint.
What can I do to improve my recovery?
When your symptoms start to ease after treatment, it’s important to get the affected joints moving again. Gentle movement of the joint can help your recovery and prevent long-term stiffness.
You may be referred to a physiotherapist, who can advise you on specific exercises to help get the joint moving.
By doing gentle exercise and completing the full course of antibiotics, most people find their joint fully recovers without any long-term damage. However, this may not always be the case.
If you are still experiencing pain following treatment you could try:
- resting the affected joint from time to time
- lifting the joint above the level of your heart if possible, to reduce swelling and pain
- applying an ice pack, such as a bag of peas wrapped in a towel, to the joint for around 20 minutes to reduce swelling and pain
- try to do some daily strengthening and stretching exercises to increase the joint’s flexibility and reduce any pain.
You can find more information about self-help in our section on managing pain.