What is the appropriate workup and initial management for a patient presenting with arthritis?

Arthritis Workup and Initial Management

Immediate Clinical Assessment

Any patient presenting with joint swelling requires immediate clinical examination to detect synovitis, followed by structured laboratory and imaging workup to differentiate inflammatory arthritis from infection, crystal arthropathy, or other causes. 1

Key Clinical Features to Document

• Joint swelling with pain or stiffness, particularly morning stiffness lasting >30 minutes, which is characteristic of inflammatory arthritis 1
• Perform a "squeeze test" of metacarpophalangeal (MCP) and metatarsophalangeal (MTP) joints to detect small joint involvement 1
• Number of joints involved (monoarticular vs polyarticular) as this guides differential diagnosis 1
• Trauma history, fever, and systemic symptoms to assess for infection or systemic disease 1
• Pattern of joint involvement: Symmetric small joint involvement suggests rheumatoid arthritis, while asymmetric large joint involvement may indicate spondyloarthropathy or crystal disease 2

Diagnostic Algorithm

Step 1: Recognize Inflammatory Arthritis

The first critical step is confirming the presence of true inflammatory arthritis rather than mechanical or degenerative disease. 3

Step 2: Exclude Specific Diagnoses

Systematically exclude definite diagnoses including systemic lupus erythematosus, psoriatic arthritis, seronegative spondyloarthropathies, crystal arthropathies, and infection. 3

Step 3: Risk Stratification

Estimate the risk of developing persistent or erosive irreversible arthritis to guide therapeutic intensity. 3

Essential Laboratory Testing

Order the following tests on initial presentation:

• Inflammatory markers: C-reactive protein (CRP) and erythrocyte sedimentation rate (ESR) provide diagnostic and prognostic information 1
• Complete blood count to identify systemic inflammation and exclude infection or malignancy 1
• Liver and renal function tests to establish baseline and rule out hepatic or renal causes 1
• Urinalysis to identify renal involvement and exclude urinary tract infection 1
• Rheumatoid factor (RF) and anti-citrullinated peptide antibodies (ACPA) for diagnostic and prognostic value in rheumatoid arthritis 1
• Antinuclear antibodies (ANA) to screen for systemic lupus erythematosus and other connective tissue diseases 1

Imaging Studies

Plain radiographs of affected joints are essential baseline imaging to evaluate for erosions, joint damage, or chondrocalcinosis, and to monitor structural progression over time. 1

Ultrasound with power Doppler is the preferred confirmatory test when clinical examination is uncertain, as it can detect synovitis, tenosynovitis, enthesitis, bone erosions, and crystal deposits at a subclinical level. 1, 4

MRI may be helpful if ultrasound and clinical examination remain inconclusive, though it significantly delays diagnosis and cannot definitively exclude infection. 1, 5

Critical Pitfall: Monoarticular Arthritis

For acute monoarticular arthritis, arthrocentesis is mandatory to rule out septic arthritis before any other intervention. 5

• Synovial fluid analysis is the gold standard and must include cell count with differential, Gram stain, culture, and crystal examination 5
• Septic arthritis is suggested by WBC >50,000/mm³ with positive Gram stain/culture and requires immediate IV antibiotics and orthopedic consultation 5
• Crystal arthropathy (CPPD or gout) can mimic infection with WBC 20,000-79,000/mm³ but has negative cultures and identifiable crystals 6, 7
• Inflammatory arthritis without infection typically shows WBC 2,000-50,000/mm³ with negative cultures 5

Never delay arthrocentesis for imaging studies like bone scan, which cannot distinguish infection from inflammation. 5

Risk Stratification for Persistent Disease

Assess the following prognostic factors to identify patients at high risk:

• Number of swollen and tender joints 1
• Elevated acute phase reactants (ESR/CRP) 1
• Presence of RF and ACPA 1
• Radiographic erosions on baseline imaging 1

These factors predict persistent arthritis and guide treatment intensity. 1

Referral Timing

Refer to rheumatology within 6 weeks of symptom onset for any patient with polyarticular swelling, positive inflammatory markers, or suspected inflammatory arthritis. 1

Immediate referral is necessary if joint swelling persists >4 weeks or if there are signs of erosive disease. 1

Initial Management

Symptomatic Treatment

NSAIDs at the minimum effective dose for the shortest duration after evaluating gastrointestinal, renal, and cardiovascular risks 1

Intra-articular corticosteroid injections can be used for large joint oligoarthritis, but only after infection is definitively excluded by arthrocentesis 1, 5

Disease-Modifying Therapy

Disease-modifying antirheumatic drugs (DMARDs), such as methotrexate, should be started within 3 months in patients at risk of persistent arthritis, preferably before the first radiographic evidence of erosions to prevent further joint damage and disability. 3, 1

Monitoring Strategy

Serial monitoring of disease activity at 1-3 month intervals using tender/swollen joint counts, patient and physician global assessments, and inflammatory markers is essential for optimizing therapeutic strategies. 1