Reactive arthritis is defined as a arthritis that occurs at 1-4 weeks after an enteral or urogenital infection, especially in individuals with HLA B27 . Reactive arthritis has two particular aspects:
- Because it differs from infectious arthritis, in reactive arthritis was not obtained culture of viable bacteria from the joint.
- There are some reactive arthritis which can not be classified as seronegative arthropathies and are not associated with HLA B27: arthritis from rheumatic fever (reactive arthritis as a consequence of reactive arthritis)
There are now considered as reactive arthritis only arthritis which can be classified as seronegative arthropathies. The onset of this disease is around 20-40 years of age with an incidence of approximately 30-40/100.000, no features related to race and sex.
In the occurrence of the reactive arthritis are involved two factors: genetic factors and infectious factors.
The genetic factor is HLA B27. Another gene that is involved in the development of reactive arthritis is TAP (transporter antigen peptide). The infectious factor it is represented by the germs which have same characteristics: the ability to synthesize lipopolisaccharide, adhere easily to the cell membrane and the ability to invade the cell of intestinal and urogenital mucosa. Among enetric bacteria are included: Shigella flexuri, Salmonella, Campylobacter, Yersinia. Urogenital bacteria involved in the development of reactive arthritis are: Clamydia trachomatis and Ureaplasma urealyticum.
The factor that triggers reactive arthritis is enteral infection which is expressed by diarrhea or urogenital infection such as urethritis, prostatitis, epididymitis, vaginitis and cervicitis which are expessed by mucopurulent discharge and dysuria. After about 1-4 weeks from the systemic manifestation, can occur articular and extra-articular manifestations.
Systemic manifestations consist of malaise, fatigue, weight loss, anorexia, fever up to 39 degrees.
The articular manifestations are:
- Peripheral arthritis which can be monoarticular or olifoarticular and affects large joints of the lower limb (knee and ankle), it has a acute and migration character and can be accompanied by signs of inflammation. Peripheral arthritis may also have chronic character, but is slowly and affects the small joints of the upper limbs;
- Axial arthritis: sacroileitis which is expressed by buttock pain and is accompanied by spondylitis;
- Entezitis which is represented by inflammation of the ahilian tendon, chest pain as a result of the inflammation of the insertion of intercostal muscles insertion and pain in the iliac crest;
- Dactylitis: swelling of the finger joints
- Hypertrophy of the quadriceps muscle.
Extra-articular manifestations are represented by cutaneous manifestations like keratoderma blenorrhagicum which is manifested by clear vesicles on erythematous background, located on the palms and plants. Another manifestation is represented by painful ulcers of the digestive tract (located especially in the mouth). In reactive arthritis can appear sterile urethritis, which has a immune mechanism.
Other extra-articular manifestations can be localized to the nails (discoloration, hyperkeratosis and onycholisis, lesions the are similar to those that appears in psoriasis) and to the eyes (conjunctivitis and anterior uveitis).
Cardiac manifestations occur in less then 10%, being the consequence of aortic root inflammation, causing aortic insufficiency and atrio-ventricular conduction disturbancens.
Can also be seen renal manifestations such as mesangial glomerulonephritis with Ig A deposis an renal amyloidosis.
Neurological manifestations associated with reactive arthritis may be peripheral neuropathy, transverse myelitis and encephalitis.
Laboratory tests may show inflammatory syndrome: ESR more than 6o mm/h, positive C-reactive protein, leukocytosis, anemia due to chronic inflammation and thrombocytosis.
Synovial fluid analysis may reveal predominant exudate with leukocytes, polymorphonuclear, glucose that is reduced, increased complement and negative cultures.
Immunology highlights negative rheumatoid factor, positive antinuclear antibodies. HLA B27 is negative in 60-80% of cases.
X-ray examination of the joints in the acute phase reveals non-specific juxtaarticular osteoporosis and soft tissue swelling. In the chronic phase, the x-ray examination reveals periostitis, marginal erosions and ankylosis.
Positive diagnosis is based on clinical examination, patient history which has a very important role and the laboratory tests.