Reactive Arthritis

Definition | Aetiology | Pathophysiology | Risk Factors | Signs and Symptoms | Investigations | Management | References

Definition

Reactive arthritis is an inflammatory condition that typically develops in response to an infection elsewhere in the body, most commonly in the urogenital or gastrointestinal tracts. It is characterised by joint pain, inflammation, and sometimes involvement of the eyes and urinary tract.

Aetiology

Reactive arthritis usually occurs after an infection, though the joints themselves are not infected. Common causes include:

• Genitourinary infections: Often caused by Chlamydia trachomatis
• Gastrointestinal infections: Common pathogens include Salmonella, Shigella, Yersinia, and Campylobacter
• Genetic predisposition, particularly the presence of the HLA-B27 gene, which increases susceptibility

Pathophysiology

The pathophysiology of reactive arthritis involves:

• Post-infectious immune response, where the body's immune system reacts to bacterial antigens that have spread from the initial site of infection to the joints
• Inflammation of synovial membranes in the joints, leading to the symptoms of arthritis
• Extra-articular manifestations, such as uveitis and urethritis, which are also driven by the immune response

Risk Factors

• Male gender, as men are more commonly affected by reactive arthritis
• Age between 20 and 40 years
• Presence of the HLA-B27 gene
• Recent infection, particularly genitourinary or gastrointestinal infections
• History of sexually transmitted infections (STIs)
• Weakened immune system

Signs and Symptoms

The signs and symptoms of reactive arthritis typically appear 1-4 weeks after the initial infection and include:

• Joint pain and swelling, often affecting the knees, ankles, and feet (typically asymmetrical)
• Enthesitis, or inflammation of the sites where tendons or ligaments attach to bone, often at the heel (Achilles tendonitis)
• Urethritis, leading to painful urination and increased urinary frequency
• Conjunctivitis or uveitis, causing redness, pain, and blurred vision in the eyes
• Skin manifestations, such as keratoderma blennorrhagicum (hyperkeratotic skin lesions) and circinate balanitis (a painless sore on the head of the penis)
• Systemic symptoms such as fever and malaise

Investigations

Specific investigations to diagnose reactive arthritis include:

• Blood tests: Raised inflammatory markers such as erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP). HLA-B27 testing may be performed to assess genetic predisposition.
• Joint aspiration: Synovial fluid analysis to rule out other causes of arthritis, such as septic arthritis or gout.
• Urethral or cervical swabs: To identify genitourinary infections, particularly Chlamydia trachomatis.
• Stool culture: To identify gastrointestinal pathogens if a preceding gastrointestinal infection is suspected.
• Imaging studies: X-rays or ultrasound may be used to assess joint damage, though imaging findings are often non-specific.

Management

Primary Care Management

• Antibiotics: If a specific infection such as Chlamydia trachomatis is identified, appropriate antibiotics should be prescribed (e.g., doxycycline or azithromycin).
• NSAIDs: Nonsteroidal anti-inflammatory drugs (e.g., ibuprofen, naproxen) are the mainstay of treatment for joint pain and inflammation.
• Pain management: Additional analgesics may be used if NSAIDs are not sufficient to control pain.
• Rest and physical therapy: Resting the affected joints during acute inflammation and engaging in physical therapy to maintain joint function and mobility as symptoms improve.

Specialist Management

• Referral to rheumatology: For patients with severe, persistent, or recurrent symptoms, or those not responding to initial treatment.
• Glucocorticoids: Intra-articular or systemic corticosteroids may be considered for severe inflammation unresponsive to NSAIDs.
• DMARDs: Disease-modifying antirheumatic drugs such as sulfasalazine or methotrexate may be considered in chronic or severe cases.
• Biologic therapy: In some cases, biologic agents like TNF inhibitors may be used, particularly in patients with persistent, refractory disease.

References

1. NHS (2024) Reactive Arthritis. Available at: https://www.nhs.uk/conditions/reactive-arthritis/ (Accessed: 24 June 2024).
2. National Institute for Health and Care Excellence (2024) Reactive Arthritis. Available at: https://cks.nice.org.uk/topics/reactive-arthritis/ (Accessed: 24 June 2024).
3. British Medical Journal (2024) Reactive Arthritis: Clinical Features, Diagnosis, and Management. Available at: https://www.bmj.com/content/350/bmj.h3005 (Accessed: 24 June 2024).
4. American College of Rheumatology (2024) Reactive Arthritis. Available at: https://www.rheumatology.org/I-Am-A/Patient-Caregiver/Diseases-Conditions/Reactive-Arthritis (Accessed: 24 June 2024).

Back to Top