SPONDYLOARTHROPATHIES (HLA-B27 ASSOCIATED)

Shared Features:

•    HLA-B27 positive (varies by condition)

•    Seronegative (RF and anti-CCP negative)

•    Axial arthritis (especially sacroiliac joints)

•    Enthesitis: inflammation at tendon insertions (e.g. Achilles, plantar fascia)

•    Dactylitis: diffuse swelling of fingers/toes ("sausage digits")

•    Anterior uveitis: painful red eye, photophobia, unilateral, recurrent

Ankylosing Spondylitis (AS)

•    Demographics: young men (<40 yrs), strong HLA-B27 association

•    Symptoms:

o    Insidious low back pain, improves with exercise/rest worsens

o    Morning stiffness >30 mins

•    Tests:

o    Schober’s test: reduced lumbar flexion

o    MRI SI joints: early sacroiliitis (detects inflammation before X-ray changes)

o    X-ray: sacroiliitis → bamboo spine (syndesmophyte formation)

•    Extra-articular features:

o    Anterior uveitis

o    Aortic regurgitation (aortitis)

o    Apical pulmonary fibrosis (late)

o    AV block (rare)

•    Management:

o    First-line: NSAIDs

o    Exercise + physiotherapy

o    Biologics: anti-TNF (e.g. etanercept) if inadequate response to NSAIDs

o    DMARDs (e.g. sulfasalazine) only for peripheral joint involvement

Psoriatic Arthritis

•    Occurs in 10–20% of psoriasis patients

•    Joint patterns (can vary):

o    Asymmetrical oligoarthritis (most common)

o    DIP joint predominant

o    Arthritis mutilans (severe destructive form)

o    Symmetrical polyarthritis (mimics RA)

•    Clinical features:

o    Dactylitis

o    Nail involvement: pitting, onycholysis

•    X-ray: "Pencil-in-cup" deformity, periostitis

•    Management:

o    NSAIDs first-line

o    DMARDs: methotrexate, sulfasalazine

o    Anti-TNF if resistant or axial disease

Reactive Arthritis

•    Cause: post-GI (Campylobacter, Shigella, Salmonella, Yersinia) or GU (Chlamydia) infection

•    Classic triad: arthritis, urethritis, conjunctivitis

•    Other features: keratoderma blennorrhagica, circinate balanitis

•    Onset: 1–4 weeks post-infection

•    Investigations:

o    HLA-B27 positive (~70%)

o    Exclude septic arthritis (especially in monoarthritis)

•    Management:

o    Treat underlying infection (e.g. doxycycline for Chlamydia)

o    NSAIDs for arthritis

o    Intra-articular steroids for persistent joint inflammation

Enteropathic Arthritis

•    Occurs in patients with IBD (Crohn’s disease or ulcerative colitis)

•    Patterns:

o    Axial: sacroiliitis/spondylitis (independent of IBD activity)

o    Peripheral: large joints (knees, ankles), parallels IBD activity

•    Treatment:

o    NSAIDs with caution (may worsen IBD)

o    Sulfasalazine, biologics (anti-TNF agents like adalimumab)