Pathophysiology & Risk Factors

Rheumatoid arthritis is a chronic systemic autoimmune disorder in which the immune system attacks the synovial membrane, producing inflammation, pannus formation, and progressive joint destruction. It targets small joints symmetrically — classically the MCP and PIP joints of both hands at once. Because it is systemic, RA can also affect the lungs, heart, and eyes, which distinguishes it from the degenerative wear-and-tear of osteoarthritis.

Rheumatoid arthritis vs Osteoarthritis

Rheumatoid ArthritisOsteoarthritis

NatureSystemic autoimmune inflammatoryDegenerative wear-and-tear

Joint patternSymmetric small joints (MCP/PIP/wrists)Asymmetric weight-bearing/large joints

Morning stiffness> 1 hour, improves with use< 30 min, worsens with activity

Joint findingsWarm, swollen, soft-tissue synovitisBony nodes (Heberden's/Bouchard's)

Systemic signsFatigue, low-grade fever, weight lossNone

Rheumatoid Arthritis

Nature: Systemic autoimmune inflammatory
Joint pattern: Symmetric small joints (MCP/PIP/wrists)
Morning stiffness: > 1 hour, improves with use
Joint findings: Warm, swollen, soft-tissue synovitis
Systemic signs: Fatigue, low-grade fever, weight loss

Osteoarthritis

Nature: Degenerative wear-and-tear
Joint pattern: Asymmetric weight-bearing/large joints
Morning stiffness: < 30 min, worsens with activity
Joint findings: Bony nodes (Heberden's/Bouchard's)
Systemic signs: None

Signs & Symptoms

EarlyProgresses →

Symmetric joint pain and swelling Hallmark

MCP/PIP of both hands

Morning stiffness > 60 minutes Hallmark

improves with activity, not rest

Warm, swollen joints

Fatigue

Low-grade fever

Weight loss

Late / Severe

Ulnar deviation

Swan-neck deformity

hyperextended PIP

Boutonnière deformity

flexed PIP

Diagnostics & Labs

Anti-CCP antibody Hallmark

more specific than RF for RA

Rheumatoid factor (RF)

can be positive in other autoimmune disease

Elevated ESR

systemic inflammation

Elevated CRP

systemic inflammation

Treatments & Medications

MethotrexatePrototype

DMARD backbone, started early; dosed weekly

Folic acid supplementation

given with methotrexate to reduce side effects

Biologic DMARDs

e.g. adalimumab (TNF inhibitor)

NSAIDs

symptom relief only; do not slow joint destruction

Corticosteroids

short-term flare control

Patient Teaching

Take methotrexate once weekly

same day each week; daily dosing causes fatal toxicity

Take prescribed folic acid

Avoid alcohol completely

additive hepatotoxicity with methotrexate

Use reliable contraception

methotrexate is a teratogen

Tuberculosis screening before biologics

TNF inhibitors reactivate latent TB

Avoid live vaccines

contraindicated with immunosuppression

Moist heat before activity

relieves stiffness

Cold for acute swelling

reserved for post-activity/flare swelling

Joint protection techniques

use large joints, assistive devices, avoid sustained grip

Balance rest and activity

splint during flares; avoid prolonged inactivity

Complications

Rheumatoid nodules

subcutaneous, extra-articular

Pericarditis

Interstitial lung disease

Scleritis

Methotrexate-induced pancytopenia

bone marrow suppression

Methotrexate hepatotoxicity

Report Nowescalate immediately

Fever on immunosuppressive therapy

methotrexate/biologics — possible myelosuppression or infection

Sore throat with fatigue

warning sign of leukopenia on methotrexate

Unusual bruising or bleeding

possible pancytopenia

Productive cough and night sweats

infection/TB reactivation on TNF inhibitor — withhold drug, notify provider

New mouth sores or oral ulcers

early methotrexate toxicity

Clinical Pearl

Symmetric and small, stiff in the morning — if both hands mirror each other and loosen up with use, think RA, not OA.