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

Management of Post-Viral Gastroenteritis Knee Pain and Swelling

Begin NSAIDs (ibuprofen) immediately as first-line therapy for this patient presenting with reactive arthritis. 1

Clinical Reasoning

This presentation is classic for reactive arthritis following gastrointestinal infection:

• Monoarticular knee involvement occurring 2 weeks post-gastroenteritis is the hallmark presentation 1
• Absence of fever and normal white blood cell count effectively exclude septic arthritis clinically 1
• The timing, clinical features, and laboratory findings align with post-infectious inflammatory arthritis rather than bacterial joint infection 1, 2

Treatment Algorithm

First-Line Pharmacologic Management

Start NSAIDs immediately without waiting for joint aspiration in this clinically non-septic presentation:

• Ibuprofen 400-800 mg three times daily OR naproxen 500 mg twice daily 1
• NSAIDs demonstrate an effect size of 0.49 in inflammatory joint conditions with effusion 1
• Ibuprofen 2400 mg/day has comparable efficacy to other NSAIDs in inflammatory arthritis 1

Risk Assessment Before NSAID Initiation

Evaluate the following before prescribing NSAIDs:

• Gastrointestinal risk: History of GI bleeding, peptic ulcer disease, or concurrent anticoagulation 3, 4
• Cardiovascular risk: History of heart failure, hypertension, or atherosclerotic disease 4
• Renal function: Chronic kidney disease or acute kidney injury risk 4
• Prescribe proton pump inhibitor for gastroprotection if GI risk factors present 1, 5

Adjunctive Non-Pharmacological Measures

Implement alongside NSAIDs:

• Patient education about reactive arthritis natural course and expected resolution 1
• Relative rest of the affected knee initially 1
• Quadriceps strengthening exercises once acute inflammation subsides 1

If Inadequate Response After 1-2 Weeks

Consider intra-articular corticosteroid injection if significant effusion persists:

• Corticosteroid injections provide effect size of 1.27 for pain relief over 7 days 6
• Particularly effective for persistent knee effusion unresponsive to NSAIDs 1, 5
• At this point, also consider joint aspiration to exclude other diagnoses 1

Why Other Options Are Incorrect

Joint Aspiration (Option C) - Not First-Line

Delaying NSAID treatment while waiting for joint aspiration in a clinically non-septic presentation is a critical pitfall to avoid 1:

• This patient lacks fever, has normal WBC, and presents 2 weeks post-viral illness—all pointing away from septic arthritis 1
• Joint aspiration is reserved for cases where infection cannot be excluded clinically or when there is inadequate response to initial therapy after 1-2 weeks 1
• The American College of Rheumatology explicitly recommends against delaying treatment in reactive arthritis presentations 1

Antibiotics (Option A) - Contraindicated

Antibiotics have no role here:

• No clinical evidence of active bacterial infection (afebrile, normal WBC) 1
• Reactive arthritis is a sterile inflammatory process occurring after infection has resolved 1, 2
• The viral gastroenteritis has already resolved 2 weeks prior 1

Corticosteroids (Option D) - Premature

Systemic corticosteroids are not first-line:

• NSAIDs should be tried first before escalating to corticosteroids 1
• Oral corticosteroids are reserved for inadequate response to NSAIDs or severe presentations 7, 1
• Intra-articular corticosteroids may be considered after 1-2 weeks if NSAIDs fail, but systemic corticosteroids are not indicated initially 1, 5

Monitoring and Follow-Up

Reassess in 1-2 weeks for treatment response:

• Monitor for NSAID complications: GI bleeding, renal dysfunction, cardiovascular effects 1, 4
• If no improvement, perform joint aspiration at that point to exclude alternative diagnoses 1
• Consider rheumatology referral if symptoms persist beyond 4 weeks 7