Spondyloarthropathies
Mariana Gonzalez Trevino
Seronegative spondyloarthropathy: family of disorders characterized inflammatory arthritis, enthesitis, and absence of serologic markers.
| Disorder | Joint Pattern | Presentation | Diagnosis | Treatment |
|---|---|---|---|---|
| Axial SpA | Bilateral sacroiliitis, spine; may have peripheral oligoarthritis (knees); enthesitis | Inflammatory back pain: onset <45 years, insidious, improves with exercise, worse at night/rest; morning stiffness >30 min; reduced spinal mobility | HLA-B27 (sensitivity 50%, specificity 90%); ESR/CRP; negative RF; X-ray pelvis (sacroiliitis, syndesmophytes, "bamboo spine"); MRI SI joints (bone marrow edema) | First-line: NSAIDs + physical therapy. Second-line: TNFi or IL-17i if inadequate response to 2 NSAIDs × 2 months. JAKi alternative. |
| Psoriatic Arthritis (PsA) | Polyarticular (symmetric); DIP involvement; enthesitis; dactylitis | Psoriasis precedes arthritis in 85% (but psoriasis can be absent); nail changes (pitting, onycholysis) in 80-90%; less tender than RA; purplish discoloration; may have uveitis, IBD | Clinical diagnosis: inflammatory arthritis + psoriasis/nail lesions/dactylitis; negative RF; juxta-articular bone formation; X-ray: "pencil-in-cup" deformity | Peripheral: MTX, SSZ, or LEF; TNFi, IL-17i, IL-23i, or JAKi for moderate-severe disease. Axial: TNFi or IL-17i (MTX not effective). Treat-to-target approach. |
| Reactive Arthritis (ReA) | Asymmetric oligoarthritis; lower extremity predominant (knees, ankles); enthesitis (Achilles, plantar fascia); dactylitis; may have sacroiliitis | Onset 1-4 weeks after GI infection (Salmonella, Shigella, Yersinia, Campylobacter) or GU infection (Chlamydia); classic triad: arthritis + urethritis + conjunctivitis; keratoderma blennorrhagicum; circinate balanitis | Clinical diagnosis: acute oligoarthritis + preceding infection; GIPP, urine cultures or PCR (Chlamydia), serologies; HLA-B27 (not diagnostic); negative RF; synovial fluid sterile | Acute: NSAIDs first-line; IA glucocorticoids. Persistent (>3-6 months): SSZ; TNFi for refractory cases. Chlamydia-induced disease may benefit from antibiotics. Self-limited in 50-70%. |
| IBD-Associated Arthritis |
Type 1 (pauciarticular):
≤5 large joints (knees, ankles);
parallels bowel activity.
Type 2 (polyarticular): ≥5 small joints; independent of bowel. Axial: sacroiliitis/AS (independent of bowel) |
Arthritis in 10-33% of IBD patients; Type 1 flares with GI disease; Type 2 more persistent; axial disease may precede IBD; associated uveitis, erythema nodosum, pyoderma gangrenosum | Clinical diagnosis in setting of IBD; HLA-B27 (53-75% in axial disease); X-ray/MRI for sacroiliitis; exclude septic arthritis (immunosuppressed patients) |
Peripheral Type 1:
Treat underlying IBD; IA steroids.
Peripheral Type 2/Axial: TNFi (infliximab, adalimumab, golimumab) or JAKi effective for both gut and joints. Avoid IL-17i (may worsen IBD). Caution: NSAIDs may flare IBD. |