OR5.1 | Inflammatory Polyarthritis Clinical Approach — Summary & Reflection

KEY TAKEAWAYS

Inflammatory vs Degenerative Arthritis: Morning stiffness >60 min, improvement with activity, MCP/PIP/wrist pattern, elevated ESR/CRP, and systemic symptoms distinguish inflammatory from degenerative (OA) joint disease.

Rheumatoid Arthritis: Autoimmune synovitis driven by HLA-DR4 + T-cell/B-cell activation produces pannus at the bare area eroding cartilage and bone. Symmetrical MCP/PIP/wrist arthritis with DIP sparing; RF (~70%) and anti-CCP (~70%, specificity ~95%); rheumatoid nodules; X-ray: periarticular osteoporosis → juxta-articular erosions. Classic deformities: ulnar deviation, Boutonnière, swan-neck. First-line DMARD: methotrexate (contraindicated in pregnancy).

Ankylosing Spondylitis: HLA-B27-associated spondyloarthropathy; enthesitis at sacroiliac joints and spine; syndesmophyte formation → bamboo spine. Inflammatory back pain in young men; Schober's test reduced; chest expansion <2.5 cm; anterior uveitis. Modified New York criteria require radiographic sacroiliitis. NSAIDs first-line (slow radiographic progression in AS); physiotherapy essential to preserve posture.

Psoriatic Arthritis: Seronegative SpA driven by IL-17/IL-23; associated with psoriasis. Five clinical patterns; pathognomonic features: dactylitis + nail changes (pitting, onycholysis). DIP involvement and pencil-in-cup X-ray deformity. Methotrexate for skin and peripheral joints; IL-17 inhibitors for biologic therapy.

DMARD Principle: NSAIDs control symptoms but do not prevent joint destruction. Methotrexate is the csDMArd anchor for RA; TNF inhibitors and IL-17 inhibitors are biologic options. Screen for latent TB before biologics in India.

REFLECT

Return to the 34-year-old teacher from the opening scenario. She has symmetrical MCP/PIP arthritis with morning stiffness lasting over an hour, fatigue, weight loss, and an ESR of 68 mm/h. Based on what you have learned: (1) Which single blood test is most specific for her likely diagnosis, and what does a positive result predict about disease course? (2) Name the specific tissue lesion responsible for progressive joint destruction in her condition and the key enzyme it secretes. (3) If her X-rays at 6 months reveal juxta-articular erosions and she has been on NSAID alone throughout, what clinical and radiological opportunity has been missed? (4) How would your management strategy for this woman differ fundamentally from the 65-year-old neighbour with osteoarthritis — and why does the correct distinction between these two conditions matter for both patients?