Reactive Arthritis

Reactive arthritis is so called because it normally occurs as a reaction a few weeks after an infection. The exact mechanism is unclear but scientists believe that either the body reacts against itself (autoimmune) or fragments of the infection get into the joint to cause inflammation.

The most common infection in the UK that triggers reactive arthritis is a gut infection such as food poisoning. Around 1-2% of people with food poisoning will develop joint inflammation after. Less commonly it can occur after sexually transmitted diseases particularly chlamydia. Occasionally it can be caused after a throat infection particularly if caused by a bacterium called streptococcus. It can also be caused by other bacterial infections or an unknown viral infection. It may also occur if you, or someone close to you, has recently had glandular fever or slapped cheek syndrome.

Who gets it? Reactive arthritis can happen to anyone but it most commonly affects men and people between 20-40 years old. Some people with reactive arthritis have a gene which makes them more susceptible. This is called the HLA-B27 gene. This gene is carried by about 7% of the population and makes you more prone to develop reactive arthritis after an infection and also more likely to develop future episodes of the condition.

Signs and symptoms of reactive arthritis typically include pain and swelling in several joints that develops suddenly 1 to 4 weeks following infection. Sometimes, the initial infection that triggered the reactive arthritis is so mild that the patient may not have noticed it. Non-joint inflammation may also occur: in the eyes as conjunctivitis, the urinary tract (urethra prostate gland, bladder), the skin, mouth, or reproductive organs. Not everyone however will get these other symptoms.

The effects of reactive arthritis on the joints can cause:

• Joint swelling and pain (especially in the lower limbs)
• Tendon swelling and pain (particularly the Achilles tendon which may cause heel pain)
• Sausage like swelling of fingers and toes (dactylitis)
• Joint stiffness especially in the morning

If the eyes are involved symptoms may include:

• Red or sore eyes
• Blurred vision
• Sensitivity to light
• Watery eyes
• Swollen eyelids

Genital tract symptoms are less common but if this system is involved symptoms may include:

• Pain when passing urine
• Smelly urine
• Cloudy urine
• Bloody urine
• Abdominal pain
• Vaginal/penile discharge

Other less common symptoms can include

• A scaly rash over the palms and feet (known as keratoderma blenorrhagica)
• Diarrhoea that may have started some time before the arthritis symptoms
• Mouth ulcers
• Weight loss and fever
• A rash at the end of the penis

There is no specific test to diagnose reactive arthritis and often doctors can diagnose the disease based on the history of the illness. For example, if the symptoms developed acutely after an STI or bowel infection or if typical symptoms such as uveitis or genital symptoms are also present specific tests may not be needed for the diagnosis.

• Some tests may be requested to help confirm the diagnosis or rule out other diseases that present similarly. These may include: X-ray or other imaging such as MRI – To examine the joint for any damage or inflammation
• FBC – to look for excess white cells which may suggest a current infection or inflammation in the body
• ESR – may rise with inflammation which would be expected in a reactive arthritis as this causes inflammation in the joints
• CRP – this may also rise with inflammation or an infection
• Rheumatoid Factor– to help rule out rheumatoid arthritiswhich can present similarly
• Autoantibodies – e.e. ANA may help rule out systemic lupus erythematosus and other rheumatological diseases
• HLA-B27- may show that the patient is at risk of reactive arthritis
• Synovial Fluid analysis– examination of joint fluid can show alternative diseases such as infection or crystals within the joint

Doctors may also look for the infection which triggered the reaction:

• Throat swab and culture
• Genital swab and culture
• Urine culture
• Stool culture
• HIV test

Reactive arthritis is usually a self-limiting condition that disappears by 6 months without any long term issues. The mainstay of treatment initially is treating the symptoms of the arthritis usually with painkillers such as paracetamol and anti-inflammatory drugs ( NSAIDS) such as ibuprofen which help with both the pain and inflammation.

Treatment of the initial infection with antibiotics may also be necessary particularly with sexually transmitted infections.

Inflamed joints can be injected with steroids or occasionally the fluid can be drained to help relieve the pain caused by the pressure of the fluid. Patients who cannot take NSAIDS or whose symptoms are particularly bad may receive a short course of oral steroids to help reduce the inflammation. In some patients the disease may persist or cause severe symptoms. If this is the case thedoctors may consider using disease modifying anti-rheumatic drugs ( DMARDS) such as methotrexate or sulfasalazine.

Occasionally symptoms may be so persistent or severe that stronger anti-rheumatic drugs known as biologics are used. It is important to note that although around 10-20% of people will have symptoms that persist past 6 months only a very small minority of these patients will need to have long-term treatment.

Often rest is required initially to control the pain and physiotherapy is also used to maintain a full range of movement. Patients may also find ice packs and heat pads help to relieve the pain as well as splints, heel and shoe pads depending on the joint(s) affected.