|Classification and external resources|
Reactive arthritis of the knee following Gonorrhea infection
Reactive arthritis is classified as an autoimmune condition that develops in response to an infection in another part of the body (cross-reactivity). Coming into contact with bacteria and developing an infection can trigger the disease. By the time the patient presents with symptoms, oftentimes the "trigger" infection has been cured or is in remission in chronic cases, thus making determination of the initial cause difficult.
The clinical pattern of reactive arthritis commonly consists of an inflammation of fewer than five joints which often includes the knee or sacroiliac joint. The arthritis may be "additive" (more joints become inflamed in addition to the primarily affected one) or "migratory" (new joints become inflamed after the initially inflamed site has already improved).
The arthritis often is coupled with other characteristic symptoms; this is called Reiter's Syndrome or Reiter's arthritis. The manifestations of Reiter's Syndrome include the following triad of symptoms: an inflammatory arthritis of large joints, inflammation of the eyes in the form of conjunctivitis or uveitis, and urethritis in men or cervicitis in women. Patients can also present with mucocutaneous lesions, as well as psoriasis-like skin lesions such as circinate balanitis, and keratoderma blennorrhagica. Enthesitis can involve the Achilles tendon resulting in heel pain. Not all affected persons have all the manifestations.
Reactive arthritis is an RF-seronegative, HLA-B27-linked arthritis often precipitated by genitourinary or gastrointestinal infections. The most common triggers are intestinal infections (with Salmonella, Shigella or Campylobacter) and sexually transmitted infections (with Chlamydia trachomatis or Neisseria gonorrheae).
It most commonly strikes individuals aged 20–40 years of age, is more common in men than in women, and more common in white than in black people. This is owing to the high frequency the of HLA-B27 gene in the white population. Patients with HIV have an increased risk of developing Reactive arthritis as well.
A large number of cases during World Wars I and II focused attention on the triad of arthritis, urethritis, and conjunctivitis (often with additional mucocutaneous lesions) which at that time was also referred to as "Fiessenger-Leroy-Reiter syndrome". These eponyms are now of historic interest only.
The condition is also known as arthritis urethritica, venereal arthritis and polyarteritis enterica. The name "Reiter’s syndrome", named after the German physician Hans Conrad Julius Reiter for his contributions to identification and description of the disease, has become unpopular in the past decade as Reiter's history of Nazi party membership, forced human experimentation in the Buchenwald concentration camp, and subsequent prosecution in Nuremberg as a war criminal, have come to light.
Signs and symptoms 
Because common systems involved include the eye, the urinary system, and the hands and feet, one clinical mnemonic for Reiter's syndrome is "Can't see, can't pee, can't climb a tree."
Symptoms generally appear within 1–3 weeks but can range from 4 to 35 days from the onset of the inciting episode of the disease.
The classical presentation of the syndrome starts with urinary symptoms such as burning pain on urination (dysuria) or an increased frequency of urination. Other urogenital problems may arise such as prostatitis in men and cervicitis, salpingitis and/or vulvovaginitis in women.
Eye involvement occurs in about 50% of men with urogenital reactive arthritis syndrome and about 75% of men with enteric reactive arthritis syndrome. Conjunctivitis and uveitis can include redness of the eyes, eye pain and irritation, or blurred vision. Eye involvement typically occurs early in the course of reactive arthritis, and symptoms may come and go.
Roughly 20 to 40 percent of the men with the disease develop penile lesions called balanitis circinata (circinate balanitis). A small percentage of men and women develop small hard nodules called keratoderma blennorrhagica on the soles of the feet and, less commonly, on the palms of the hands or elsewhere. In addition, some individuals with reactive arthritis develop mouth ulcers that come and go. In some cases, these ulcers are painless and go unnoticed. Some patients suffer serious gastrointestinal problems similar to those of the Crohn's disease.
About 10 percent of the people with reactive arthritis, especially those with a prolonged course of the disease, will develop cardiac manifestations, including aortic regurgitation and pericarditis. Reiter's Syndrome has been described as a pre-cursor for other joint conditions, including ankylosing spondylitis.
It is set off by a preceding infection, the most common of which would be a genital infection with Chlamydia trachomatis in the US. Other bacteria known to cause reactive arthritis which are more common worldwide are Ureaplasma urealyticum, Salmonella spp., Shigella spp., Yersinia spp., and Campylobacter spp. A bout of food poisoning or a gastrointestinal infection may also precede the disease (those last four genera of bacteria mentioned are enteric bacteria). There is some circumstantial evidence for other organisms causing the disease, but the details are unclear. Reiter's Syndrome usually manifests about 1–3 weeks after a known infection. The mechanism of interaction between the infecting organism and the host is unknown. Synovial fluid cultures are negative, suggesting that reactive arthritis is caused either by an over-stimulated autoimmune response or by bacterial antigens which have somehow become deposited in the joints.
There are few clinical symptoms, but the clinical picture is dominated by arthritis in one or more joints, resulting in pain, swelling, redness, and heat sensation in the affected areas.
Tests for C-reactive protein and erythrocyte sedimentation rate are non-specific tests that can be done to corroborate the diagnosis of the syndrome. Also, a blood test for the genetic marker HLA-B27 may be performed. About 75 percent of all the patients with Reiter's arthritis display this gene.
Diagnostic Criteria 
|Percent Sensitivity and Specificity of Various Criteria for Typical Reiter's Syndrome|
|Method of diagnosis||Sensitivity||Specificity|
|1. Episode of arthritis of more than 1 month with urethritis and/or cervicitis||84.3%||98.2%|
|2. Episode of arthritis of more than 1 month and either urethritis or cervicitis, or bilateral conjunctivitis||85.5%||96.4%|
|3. Episode of arthritis, conjunctivitis, and urethritis||50.6%||98.8%|
|4. Episode of arthritis of more than 1 month, conjunctivitis, and urethritis||48.2%||98.8%|
The main goal of treatment is to identify and eradicate the underlying infectious source with the appropriate antibiotics if still present. Otherwise, treatment is symptomatic for each problem. Analgesics particularly NSAIDs, sulfasalazine, steroids and immunosuppressants may be needed for patients with severe reactive symptoms that do not respond to any other treatment.
Reactive arthritis may be self-limiting, frequently recurring, chronic or progressive. Most patients have severe symptoms lasting a few weeks to six months. Fifteen to 50 percent of cases have recurrent bouts of arthritis. Chronic arthritis or sacroiliitis occurs in 15-30 percent of cases. Repeated attacks over many years are common, and patients sometimes end up with chronic and disabling arthritis, heart disease, amyloid deposits, ankylosing spondylitis, immunoglobulin A nephropathy, cardiac conduction abnormalities, or aortitis with aortic regurgitation. However, most people with reactive arthritis can expect to live normal life spans and maintain a near-normal lifestyle with modest adaptations to protect the involved organs.
Because women may be underdiagnosed, the exact incidence of reactive arthritis is difficult to estimate. A few studies have been completed, though. In Norway between 1988 and 1990, incidence was 4.6 cases per 100,000 for Chlamydia-induced Reiter's Syndrome and 5 cases per 100,000 for that induced by enteric bacteria. In 1978 in Finland, the annual incidence was found to be 43.6 per 100,000.
Famous individuals 
- It has been postulated that Italian-born explorer Christopher Columbus suffered from Reiter's arthritis, dying from a heart attack caused by the condition.
- Scottish football player Ian Murray has suffered from Reiter's arthritis.
- Australian singer, and frontman of the band silverchair, Daniel Johns was diagnosed with Reactive Arthritis in early 2002 which prevented the band from touring their new album Diorama.
- Former KISS guitarist Mark St. John also suffered with reactive arthritis, which prevented him from playing live shows and limited his tenure in the band.
- Mayo Staff (March 5, 2011). "Reactive Arthritis (Reiter's Syndrome)". Mayo Clinic. Retrieved May 16, 2011.
- Primer on the Rheumatic Diseases, By John H. Klippel, page 218
- Rheumatology in Practice, By J. A. Pereira da Silva, Anthony D. Woolf page 5.9
- H. Hunter Handsfield (2001). Color atlas and synopsis of sexually transmitted diseases, Volume 236. McGraw-Hill Professional. p. 148. ISBN 978-0-07-026033-7.
- Ruddy, Shaun (2001). Kelley's Textbook of Rheumatology, 6th Ed. W. B. Saunders. pp. 1055–1064. ISBN 0-7216-9033-5.
- Sampaio-Barros PD, Bortoluzzo AB, Conde RA, Costallat LT, Samara AM, Bértolo MB (June 2010). "Undifferentiated spondyloarthritis: a longterm followup". The Journal of Rheumatology (The Journal of Rheumatology) 37 (6): 1195–1199. doi:10.3899/jrheum.090625. PMID 20436080.
- Geirsson AJ, Eyjolfsdottir H, Bjornsdottir G, Kristjansson K, Gudbjornsson B (May 2010). "Prevalence and clinical characteristics of ankylosing spondylitis in Iceland - a nationwide study". Clinical and experimental rheumatology (Clinical and Experimental Rheumatology) 28 (3): 333–40. PMID 20406616.
- Harrison's Rheumatology, Second Edition [Anthony Fauci, Carol Langford], Ch.9 THE SPONDYLOARTHRITIDES, Reactive Arthritis, page.134
- Wallace, D. J.; Weisman, M. (2000). "Should a war criminal be rewarded with eponymous distinction? The double life of Hans Reiter (1881–1969)". JCR: Journal of Clinical Rheumatology 6 (1): 49–54. doi:10.1097/00124743-200002000-00009. PMID 19078450.
- Zadik Y, Drucker S, Pallmon S (Aug 2011). "Migratory stomatitis (ectopic geographic tongue) on the floor of the mouth". J Am Acad Dermatol 65 (2): 459–60. doi:10.1016/j.jaad.2010.04.016. PMID 21763590.
- Hill Gaston JS, Lillicrap MS (2003). "Arthritis associated with enteric infection". Best pract ice & research. Clinical rheumatology 17 (2): 219–239. doi:10.1016/S1521-6942(02)00104-3. PMID 12787523.
- Paget, Stephen (2000). Manual of Rheumatology and Outpatient Orthopedic Disorders: Diagnosis and Therapy (4th ed.). Lippincott, Williams, & Wilkins. pp. chapter 36. ISBN 0-7817-1576-8.
- American College of Rheumatology. "Arthritis and Rheumatism". Retrieved May 16, 2011.
- eMedicine/Medscape (Jan 5, 2010). "Reactive Arthritis". Retrieved May 16, 2011.
- Kvien, T.; Glennas, A.; Melby, K.; Granfors, K et al. (1994). "Reactive arthritis: Incidence, triggering agents and clinical presentation". Journal of Rheumatology 21 (1): 115–22. PMID 8151565.
- Isomäki, H.; Raunio, J.; von Essen, R.; Hämeenkorpi, R. (1979). "Incidence of rheumatic diseases in Finland". Scandinavian Journal of Rheumatology 7 (3): 188–192. doi:10.3109/03009747809095652. PMID 310157.
- "Cause of the death of Columbus (in Spanish)". Eluniversal.com.mx. Retrieved 29 July 2009.
- Lisa Gray (Nov 29, 2006). "Murray targets Christmas as date for Rangers return". The Independent.
- Reactive arthritis topic list - Merck Manual
- Reiter's Syndrome - WrongDiagnosis.com
- MorbusReiter.de one patient of the rare reactive arthritis is offering to other patients a platform with information, guestbook and forum.