What is the most appropriate management for a patient presenting with knee pain and swelling two weeks after recovering from viral gastroenteritis, with no fever and a normal white blood cell count?

Reactive Arthritis: Begin NSAIDs (Ibuprofen)

The most appropriate management for this patient is to begin NSAIDs (ibuprofen), as this presentation is highly consistent with reactive arthritis following viral gastroenteritis, which requires anti-inflammatory treatment rather than antibiotics, joint aspiration, or corticosteroids as first-line therapy. 1, 2

Clinical Reasoning

This patient presents with classic features of reactive arthritis (formerly Reiter's syndrome):

• Monoarticular knee involvement developing 2 weeks post-viral gastroenteritis 3, 4
• Absence of septic arthritis indicators: no fever and normal white blood cell count 5
• Post-infectious timing: the 2-week interval is typical for reactive arthritis following gastrointestinal infections 6

Why NSAIDs Are First-Line

Primary Treatment Rationale

• NSAIDs are specifically indicated for inflammatory arthritis with effusion, demonstrating efficacy with effect size median of 0.49 in inflammatory joint conditions 1, 2
• For knee effusion with inflammatory signs, NSAIDs should be considered as the initial pharmacologic approach, particularly when infection has been excluded clinically 5
• Ibuprofen 2400 mg/day has demonstrated comparable efficacy to other NSAIDs in inflammatory arthritis 5

Why NOT the Other Options

Option A (Antibiotics): Inappropriate because:

• No clinical evidence of septic arthritis (afebrile, normal WBC) 5
• Reactive arthritis is a sterile inflammatory process—the joint inflammation occurs without active bacterial infection in the joint space 6

Option C (Joint Aspiration): Not immediately necessary because:

• Joint aspiration is indicated when septic arthritis cannot be excluded clinically 5
• This patient has clear exclusionary features: no fever, normal WBC, and obvious post-viral trigger 5
• Aspiration would be appropriate if the patient had fever, elevated WBC, or failed to respond to NSAIDs 1

Option D (Corticosteroids): Premature at this stage because:

• Intra-articular corticosteroids are indicated for acute exacerbations with effusion, but typically after NSAIDs have been tried or in more severe presentations 1, 2
• The treatment algorithm recommends NSAIDs before escalating to corticosteroids 5
• Systemic corticosteroids would only be considered for severe, refractory cases 5

Treatment Algorithm

Initial Management (Current Patient)

• Start NSAIDs: Ibuprofen 400-800 mg three times daily or naproxen 500 mg twice daily 5
• Assess gastrointestinal and cardiovascular risk before initiating NSAIDs 5
• Consider gastroprotection (proton pump inhibitor) if risk factors present 5

If Inadequate Response After 1-2 Weeks

• Consider intra-articular corticosteroid injection if significant effusion persists 1, 2
• Long-acting corticosteroid provides significant pain relief within 1-2 weeks, especially effective when effusion is present 2

Adjunctive Non-Pharmacological Measures

• Patient education about reactive arthritis and expected course 5
• Relative rest of the affected joint initially 1
• Quadriceps strengthening exercises once acute inflammation subsides 1, 2

Critical Pitfalls to Avoid

• Do not delay NSAID treatment waiting for joint aspiration in a clinically non-septic presentation 5
• Do not start antibiotics empirically without evidence of bacterial infection—this is a sterile inflammatory process 6
• Monitor for NSAID complications: gastrointestinal bleeding, renal dysfunction, cardiovascular effects 5
• Reassess if no improvement in 1-2 weeks—consider joint aspiration at that point to exclude other diagnoses 1