QuestionSBA
QuestionChoice
This is a classic presentation of reactive arthritis (triad arthritis, urethritis and conjunctivitis). It is usually caused by gastrointestinal/genituo-urinary infections. Given the urinary symptoms, arranging urinary NAAT testing is likely to be diagnostic of the causative organism.
10017161
a
Arrange urinary NAAT testing
QuestionChoice
Whilst gastrointestinal infections can trigger reactive arthritis, there is no mention of diarrhoea or other GI symptoms, whilst there is suspicion for urethral infection.
10017165
e
Obtain stool cultures for PCR and culture
QuestionChoice
This would be appropriate management for a confirmed crystal arthropathy (e.g. gout/pseudogout). However, the symptoms are far more suggestive of a reactive arthritis with active underlying infection, which would need to be treated on top of symptomatic analgesia.
10017163
c
Commence colchicine and discharge with safety netting advice
QuestionChoice
Whilst a red, hot and swollen joint should always raise suspicion for septic arthritis, this would likely lead to limited range of motion and be exquisitely tender on palpation. Although joint aspiration may be useful, this history (and lack of fever) is far more suggestive of a reactive arthritis.
10017162
b
Arrange urgent joint aspiration
QuestionChoice
This would be more useful in a scenario with suspected meniscal or ligament injury following trauma. It additionally would be unlikely to be used as a first line investigation.
10017164
d
Arrange urgent knee MRI
QuestionComment
Would you not want to rule out septic arthritis? 
43836
QuestionComment
true, but the q asks for management given most likely dx, and whilst you need to rule out septic arthritis, it isn't the most likely dx. 
59324
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Thermoregulator Relapse
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Parok
QuestionComment
If I'm not wrong you need to rule out septic arthritis first before starting treatment 
48460
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Edema Dominant
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# Summary

Reactive arthritis is a sterile inflammatory arthritis that typically occurs within four weeks of an infection. Infections are often sexually transmitted (e.g. Chlamydia trachomatis) or gastrointestinal (e.g. Salmonella, Shigella or Campylobacter). Patients present with joint pain, stiffness and swelling which is usually asymmetrical and affects few joints, predominantly lower extremity. The classic triad of symptoms is of arthritis, conjunctivitis and urethritis; other associated features include rashes, nail changes and mouth ulcers. Investigations involve testing for the causative infection, synovial fluid analysis to exclude differentials, and X-ray imaging of affected joints. Reactive arthritis is a self-limiting condition in the majority of patients and so management is symptomatic. NSAIDs are usually first line and either local or systemic steroids may be used if NSAIDs are contraindicated or ineffective. If ongoing infection is identified (e.g. Chlamydia) this should be treated and referral to genitourinary medicine made to investigate for other sexually transmitted infections and arrange contact tracing.

# Definition

Reactive arthritis (ReA) is a type of inflammatory arthritis that occurs secondary to a recent infection, usually genitourinary or gastrointestinal in nature. It is described as "sterile", meaning that the affected joints are not themselves infected. 

Reactive arthritis was originally referred to as Reiter's syndrome, which refers to the classic triad of conjunctivitis, urethritis and arthritis (remembered with the mnemonic "can't see, can't pee, can't climb a tree).

# Aetiology

- The triggering infection occurs up to a month before the onset of arthritis
- Most infections are sexually transmitted (postvenereal ReA) or gastrointestinal (postenteric ReA)
- Common causative organisms include:
- Chlamydia trachomatis 
- Campylobacter jejuni
- Salmonella
- Shigella
- Yersinia
- Less common causes include E coli, HIV, Neisseria gonorrhoea and Mycoplasma pneumoniae
- Postvenereal ReA is mainly seen in men aged 20-30
- Postenteric ReA affects both sexes equally
- There may not be an identifiable triggering infection in all cases
- Patients who are HLA-B27 positive have a 50x increased risk of ReA and are more likely to have severe and persistent symptoms

# Signs and Symptoms

- **Arthritis**
- Typically this is asymmetrical and primarily affects the large joints of the lower limbs
- Usually oligoarticular (affecting few joints)
- A small joint polyarthritis in the upper limbs may also occur
- Axial involvement and sacroiliitis are more common with urogenital rather than enteric ReA
- **Dactylitis** refers to swelling of an entire digit (finger or toe)
- **Enthesitis** causes pain and swelling at sites of tendon or ligament insertions into bone
- Achilles tendonitis and plantar fasciitis are common and cause pain on walking
- **Keratoderma blennorhagicum** is the classic rash of ReA
- Pustular lesions form on the palms and soles of the feet 
- These become hyperkeratotic and scaly and form plaques
- **Circinate balanitis** refers to red or grey plaques with an irregular white margin that form on the penis (the shaft or the glans)
- **Oral ulceration**
- **Nail dystrophy**
- **Eye involvement** may be the first presenting feature, with manifestations including:
- Conjunctivitis
- Anterior uveitis
- Keratitis
- Episcleritis
- **Genitourinary features** may occur in both postvenereal and postenteric ReA, including:
- Urethritis or cervicitis
- Cystitis
- Prostatitis
- Salpingo-oophoritis
- **Constitutional symptoms** are often present and include:
- Fevers
- Malaise
- Fatigue

[lightgallery] [lightgallery1] [lightgallery2] 

# Differential Diagnosis

- **Gonococcal arthritis** occurs in the context of disseminated infection and may present with joint pain and swelling, tenosynovitis and dermatitis - swabs should be taken from relevant sites including the rectum, pharynx, urethra and cervix and synovial fluid cultures may be positive
- **Other spondyloarthritides** including ankylosing spondylitis, enteric arthritis and psoriatic arthritis can present with similar features of peripheral arthritis, enthesitis and dactylitis however these are not temporally related to a triggering infection and tend not to self-resolve
- **Viral infections** may cause arthritis as well as extra articular features of fevers, rashes and conjunctivitis e.g. enteroviruses, Coxsackievirus, Chikungunya
- **Septic arthritis** usually presents with a single inflamed joint accompanied by systemic features of fevers and malaise; aspiration and analysis of synovial fluid is the key investigation
- **Rheumatic fever** occurs in a similar timeframe to reactive arthritis after initial streptococcal infection (usually a sore throat), and shares features of polyarthritis and rashes (classically erythema marginatum); other features include carditis and chorea

# Investigations

**Bedside tests:**

- **Chlamydia trachomatis and gonorrhoea testing** should be done with nucleic acid amplification tests (NAAT) on urine or a urethral/vulvovaginal swab
- In patients with a history of oral or anal sexual intercourse, pharyngeal and/or rectal swabs should also be tested
- Antibiotic sensitivity testing is required for positive samples
- **Stool MC&S**, **viral PCR** and **Clostridium difficile testing** should be done in patients with ongoing diarrhoea (although usually this has resolved by the time ReA develops)
- **Aspiration of synovial fluid** should usually be carried out to rule out septic arthritis or crystal arthropathies - in ReA cultures will be negative but white cell count is high

**Blood tests:**

- **FBC** is usually indicative of inflammation with a normocytic anaemia, mildly raised white cell count and thrombocytosis
- **CRP** and **ESR** are raised acutely and normalise with time
- **HIV testing** should be offered as people with HIV have an increased risk of ReA
- Testing for other sexually transmitted infections including **syphilis, hepatitis B and C** should be considered 
- **HLA-B27** is often positive in patients with ReA and is a poor prognostic marker
- **Serology** for other infections may be indicated e.g. salmonella or shigella

**Imaging:**

- **X-rays** of affected joints which may be normal early on in the disease course
- Imaging features include erosions, enthesopathy with bony spur formation, loss of joint space and soft tissue swelling
- Sacroiliitis may be seen on X-ray however **MRI** is more sensitive for joint erosions in the acute phase

# Management

- Patients diagnosed with a sexually transmitted disease (usually Chlamydia trachomatis) should be referred to a sexual health specialist to be assessed for other infections and for contact tracing
- Patients with chlamydia and their partners should be treated with antibiotics (usually 7 days of oral doxycycline)
- Otherwise, management of joint symptoms is usually symptomatic with NSAIDs being first-line
- If NSAIDs are contraindicated or ineffective, local steroid injections for affected joints (or systemic steroids if many joints are affected) may be used
- Bone and stomach protection should be considered for all patients who require oral steroid treatment
- In patients with persistent disease, conventional DMARDs should be initiated with sulfasalazine being the preferred medication
- Biologics can be initiated if conventional DMARDs are ineffective, with anti-TNF agents such as etanercept being first-line options
- Additional treatment may be required for significant skin involvement, with topical treatments including steroids, salicylic acid and vitamin D analogues

# Prognosis

- In most patients, disease is self-limiting with a duration of around 3 to 5 months
- However in 25% of patients symptoms persist for longer than 6 months (referred to as chronic ReA) 
- Recurrence of disease may also occur, which may be in response to another infective trigger
- Secondary osteoarthritis may complicate reactive arthritis due to inflammatory joint damage

# References

[Reactive arthritis: a clinical review](https://www.rcpe.ac.uk/sites/default/files/jrcpe_51_3_jubber.pdf)

[Patient UK - Reactive Arthritis](https://patient.info/doctor/reactive-arthritis-pro)

[Radiopaedia - Reactive Arthritis](https://radiopaedia.org/articles/reactive-arthritis?lang=gb)
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Keratoderma blenorrhagica.
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Dactylitis.
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The typical appearance of anterior uveitis.
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Reactive arthritis
Topic
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Rheumatology
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Urinary NAAT (nucleic acid amplification test) is a highly sensitive test for detecting Chlamydia trachomatis and Neisseria gonorrhoeae infections, which can trigger reactive arthritis, an inflammatory joint condition often linked to urogenital or gastrointestinal infections.
A 21-year-old male has a painful left knee. He has also noticed he has a left red eye and pain on urination in the last week. On examination, his knee is swollen and mildly tender, but he has a full range of motion and can weight bear. The patient is afebrile.

Given the likely diagnosis, what is the most appropriate management?
a