Enteropathic Arthritis

Overview

Enteropathic arthritis is a subtype of spondyloarthropathy associated with inflammatory bowel disease (IBD), particularly Crohn’s disease and ulcerative colitis. It affects up to 20% of IBD patients, with a variable presentation involving axial and/or peripheral joints. The arthritis may run parallel to intestinal disease activity or occur independently, often with enthesitis or dactylitis. It has no gender predilection and usually presents in young adults (20–40 years).

Aetiology and Risk Factors

• Inflammatory bowel disease (Crohn’s or UC) is the key associated condition
• Genetics: HLA-B27 in 30–50% of axial enteropathic arthritis
• Microbiome dysregulation: Gut barrier dysfunction triggers immune activation
• Smoking: Risk factor for Crohn’s and worsens joint disease
• Family history of spondyloarthropathy

Pathophysiology

• Loss of intestinal barrier integrity → translocation of microbial antigens
• Activation of innate and adaptive immunity (Th17, IL-23 axis)
• Immune-mediated joint inflammation (molecular mimicry, shared antigens)
• In axial disease, chronic enthesitis may lead to new bone formation and ankylosis

Clinical Manifestations

• Axial disease: Inflammatory back pain, sacroiliitis, stiffness improving with activity
• Peripheral arthritis:
  – Type 1: Acute, self-limiting oligoarthritis, <5 large joints (often parallels IBD activity)
  – Type 2: Chronic, polyarticular, >5 joints (independent of bowel activity)
• Enthesitis: Achilles tendon, plantar fascia
• Dactylitis
• Extra-articular features:
  – Uveitis
  – Erythema nodosum
  – Pyoderma gangrenosum
  – Nail clubbing
  – Constitutional symptoms (fatigue, malaise)

Diagnosis

No formal diagnostic criteria specific to enteropathic arthritis; typically classified under spondyloarthritis using:

• ASAS classification criteria for axial and peripheral SpA
• Presence of IBD is a major SpA feature under these criteria

Investigations

• ESR/CRP: Often elevated during flares
• HLA-B27: More common in axial disease
• X-rays: Sacroiliitis, syndesmophytes, asymmetric joint space narrowing
• MRI: Early detection of sacroiliitis (bone marrow edema, erosions)
• Exclude infections, especially in reactive or enteric-triggered arthritis

Differential Diagnoses:

Condition	Clinical features
Reactive arthritis	Recent GI/GU infection, resolves in 6 months
Psoriatic arthritis	Skin and nail psoriasis, dactylitis, family history
Rheumatoid arthritis	Symmetric polyarthritis, positive RF/anti-CCP
Septic arthritis	Acute monoarthritis, fever, positive culture

Treatment

Non-pharmacological:
• Physiotherapy and joint protection
• Manage IBD with gastroenterologist collaboration

Pharmacological:
• NSAIDs: Use with caution in IBD (can exacerbate bowel symptoms)
• Corticosteroids: Short-term for flares
• Sulfasalazine: Effective in peripheral arthritis
• Methotrexate: Consider for peripheral involvement, especially in Crohn’s
• Anti-TNF agents (infliximab, adalimumab): Effective for both joint and gut inflammation
• IL-12/23 inhibitors (ustekinumab): Used in Crohn’s with joint symptoms
• IL-17 inhibitors (e.g. secukinumab) are not recommended in IBD

Complications and Prognosis

Complications

• Joint damage and deformity from chronic inflammation
• Spinal fusion/ankylosis in axial disease
• Reduced quality of life due to persistent joint and bowel symptoms
• IBD complications: strictures, fistulas, colorectal cancer (especially in UC)

Poor prognostic factors
– Early-onset polyarthritis
– Persistent IBD activity
– Axial involvement with HLA-B27
– Delay in diagnosis and treatment

References

1. Orchard TR, Wordsworth BP, Jewell DP. Peripheral arthropathies in inflammatory bowel disease: their articular distribution and natural history. Gut. 1998;42(3):387–391.
2. Harbord M, Annese V, Vavricka SR, et al. The First European Evidence-based Consensus on Extra-intestinal Manifestations in Inflammatory Bowel Disease. J Crohns Colitis. 2016;10(3):239–254.
3. Rudwaleit M, van der Heijde D, Landewe R, et al. The development of Assessment of SpondyloArthritis International Society classification criteria for axial spondyloarthritis. Ann Rheum Dis. 2009;68(6):770–776.
4. Fragoulis GE, Liava C, Daoussis D, et al. Inflammatory bowel diseases and spondyloarthropathies: From pathogenesis to treatment. World J Gastroenterol. 2019;25(18):2162–2176.