A 62-year-old man is evaluated in the emergency department for severe right knee pain that… — USMLE Step 2 CK

A $62$ -year-old man is evaluated in the emergency department for severe right knee pain that began abruptly during the night. The patient states the pain is so intense that he cannot bear weight or tolerate the bedsheet touching his knee. His past medical history includes hypertension, diet-controlled type 2 diabetes mellitus, and stage 4 chronic kidney disease with a baseline estimated glomerular filtration rate of $22 \text{ mL/min}/1.73 \text{ m}^2$ . His current medications are amlodipine and atorvastatin. Vital signs show a temperature of $37.6^\circ\text{C}$ ( $99.7^\circ\text{F}$ ), blood pressure of $145/88 \text{ mm Hg}$ , and heart rate of $94/\text{min}$ . Physical examination reveals a markedly swollen, erythematous, and exquisitely tender right knee. A joint aspiration is performed. Synovial fluid analysis shows a leukocyte count of $42,000/\text{mm}^3$ with $82\%$ segmented neutrophils. Gram stain of the fluid demonstrates no organisms. Polarized light microscopy reveals the presence of needle-shaped crystals with strong negative birefringence. Which of the following is the most appropriate next step in management?

Intra-articular methylprednisoloneAnswer
B
Intravenous ceftriaxone
C
Oral indomethacin
D
Oral colchicine
E
Oral allopurinol

Answer

Intra-articular methylprednisolone

The most appropriate management for this patient is an intra-articular injection of a glucocorticoid such as methylprednisolone. The patient is experiencing an acute monoarticular flare of gout, confirmed by the presence of needle-shaped, negatively birefringent crystals in the synovial fluid. While NSAIDs (e.g., indomethacin) and colchicine are typical first-line oral therapies for acute gout, both are highly problematic in this patient due to his stage 4 chronic kidney disease. NSAIDs can precipitate acute renal failure, and colchicine carries a high risk of severe toxicity due to decreased renal clearance. Because only a single joint is involved and infectious arthritis has been reasonably excluded (negative Gram stain), an intra-articular glucocorticoid injection is the safest and most effective option, offering rapid anti-inflammatory action with minimal systemic absorption.

Step-by-Step Solution

Analyze the synovial fluid results.

Fluid shows marked leukocytosis with needle-shaped, negatively birefringent crystals and a negative Gram stain.

This definitively confirms the diagnosis of an acute gout flare and makes a concurrent bacterial infection highly unlikely.

Evaluate the patient's medical history and comorbidities.

The patient has stage 4 chronic kidney disease (eGFR of

22 \text{ mL/min}/1.73 \text{ m}^2

Renal function directly dictates the safety profile of standard gout therapies (NSAIDs, colchicine, and systemic glucocorticoids).

Select the safest and most effective targeted pharmacotherapy.

Intra-articular glucocorticoids (methylprednisolone) are chosen.

First-line agents like NSAIDs and colchicine are contraindicated in advanced CKD. A local joint injection provides rapid relief with minimal systemic side effects.

Key Concept

Management of acute gout flares in patients with severe chronic kidney disease.

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