What is the initial workup and management for a patient with a swollen joint?

Initial Workup for a Swollen Joint

A patient presenting with a swollen joint requires immediate clinical examination to detect synovitis, followed by a structured laboratory and imaging workup to differentiate inflammatory arthritis from infection, crystal arthropathy, or other causes—with urgent rheumatology referral within 6 weeks if inflammatory arthritis is suspected. 1

Clinical Assessment

History and Physical Examination:

• Document the presence of joint swelling associated with pain or stiffness, particularly morning stiffness lasting >30 minutes 1
• Perform a "squeeze test" for metacarpophalangeal (MCP) and metatarsophalangeal (MTP) joints to detect small joint involvement 1
• Assess for trauma history, fever, systemic symptoms, and number of joints involved (monoarticular vs polyarticular) 1, 2
• Examine for erythema, warmth, range of motion limitations, and spine involvement 1
• Critical pitfall: Infection must be excluded before any corticosteroid injection is considered 2

Laboratory Testing

Essential Initial Panel:

• Inflammatory markers: C-reactive protein (CRP) and erythrocyte sedimentation rate (ESR) for diagnostic and prognostic information 1, 3
• Complete blood count to identify systemic inflammation and exclude infection or malignancy 1, 3
• Liver function tests (transaminases) to establish baseline and rule out hepatic causes 1, 3
• Renal function tests to establish baseline and assess for renal involvement 1, 3
• Urinalysis to identify renal involvement and exclude urinary tract infection 1, 3

Autoimmune Screening:

• Rheumatoid factor (RF) for diagnostic and prognostic value in rheumatoid arthritis 1, 3
• Anti-citrullinated peptide antibodies (ACPA) to assess risk of persistent and erosive disease 1, 3
• Antinuclear antibodies (ANA) to screen for systemic lupus erythematosus and other connective tissue diseases 1, 3

Additional Testing When Indicated:

• Consider HLA-B27 if symptoms suggest reactive arthritis or axial involvement 1
• Anti-CCP antibodies if rheumatoid arthritis is suspected 1

Imaging Studies

Plain Radiography:

• Obtain plain x-rays of affected joints to evaluate for erosions, joint damage, or metastatic lesions 1, 3
• Baseline radiographs are essential for monitoring structural progression 3

Advanced Imaging (When Clinical Examination is Equivocal):

• Ultrasound with power Doppler is the preferred confirmatory test for detecting synovitis when clinical examination is uncertain 1
• MRI may be helpful if ultrasound and clinical examination remain inconclusive 1

Joint Aspiration (Critical for Monoarticular Swelling)

Indications:

• Any acute monoarticular swelling, especially if warm or erythematous, to exclude septic arthritis 2, 4
• Persistent symptoms despite initial management 1

Synovial Fluid Analysis:

• Gram stain and culture (discontinue antibiotics 2-4 weeks prior if possible to reduce false negatives) 5
• Cell count with differential 4
• Crystal analysis for gout and pseudogout 1
• Consider Lyme antigen testing in endemic areas with appropriate clinical context 6

Risk Stratification for Persistent Disease

Assess the Following Prognostic Factors:

• Number of swollen and tender joints 1, 7
• Elevated acute phase reactants (ESR/CRP) 1, 7
• Presence of RF and ACPA 1, 7
• Radiographic erosions on baseline imaging 1, 7

Referral and Monitoring

Rheumatology Referral:

• Refer within 6 weeks of symptom onset for any patient with polyarticular swelling, positive inflammatory markers, or suspected inflammatory arthritis 1
• Immediate referral if joint swelling (synovitis) persists >4 weeks or if there are signs of erosive disease 1

Serial Monitoring:

• Assess disease activity at 1-3 month intervals using tender/swollen joint counts, patient and physician global assessments, and inflammatory markers 1
• Repeat radiographs every 6-12 months during the first few years to monitor for structural damage 7
• If initial tests are negative but symptoms persist, repeat laboratory testing in 3-6 months 3

Initial Management Considerations

Symptomatic Treatment:

• NSAIDs at the minimum effective dose for the shortest duration after evaluating gastrointestinal, renal, and cardiovascular risks 1, 8
• Intra-articular corticosteroid injections for large joint oligoarthritis (only after infection is excluded) 1

Disease-Modifying Therapy:

• Patients at risk of persistent arthritis should start DMARDs within 3 months, with methotrexate as the anchor drug unless contraindicated 1
• Early treatment (within 6 weeks) improves long-term outcomes 1

Critical Pitfalls to Avoid

• Never inject corticosteroids until infection is completely excluded 2
• Do not rely solely on laboratory tests without thorough clinical examination—this leads to misdiagnosis in 20-30% of cases 3
• Do not delay rheumatology referral—more than 80% of patients with disease duration <2 years already show radiographic joint damage 7
• Immunosuppressed patients, those with malignancy, or preexisting joint disease (e.g., rheumatoid arthritis) are at particular risk for septic arthritis and require aggressive evaluation 2