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Difficulty: HardRheumatology and Immunology

Rheumatology consultation is requested for a 74-year-old man who developed sudden, excruciating pain and swelling in his right knee overnight. The patient is currently recovering on the surgical ward on postoperative day 4 following an open cholecystectomy for acute cholecystitis. His medical background is significant for long-standing hypertension, diet-controlled type 2 diabetes, and stage 3b chronic kidney disease. He is receiving prophylactic subcutaneous enoxaparin. Temperature is 37.9°C (100.2°F). The right knee is markedly erythematous, warm to the touch, and held in slight flexion; any attempted movement elicits severe distress. Laboratory evaluation reveals a serum creatinine of 2.3 mg/dL. An ultrasound-guided diagnostic arthrocentesis yields 35,000 leukocytes/mm³ (85% neutrophils). Microscopic examination under polarized light demonstrates multiple rhomboid-shaped crystals with weak positive birefringence. Gram stain of the synovial fluid is negative for microorganisms. Which of the following is the most appropriate next step in management?

  1. Intra-articular glucocorticoid injectionAnswer
  2. B
    Intravenous vancomycin and ceftriaxone
  3. C
    Oral indomethacin
  4. D
    Oral colchicine
  5. E
    Initiation of oral allopurinol

Answer

The correct approach is an intra-articular glucocorticoid injection.
The correct answer provides the most effective and localized treatment for a monoarticular flare of pseudogout, completely bypassing the patient's renal contraindications. Intra-articular glucocorticoids are the treatment of choice for acute crystal arthropathy involving 1-2 joints when systemic NSAIDs and colchicine are unsafe.

Step-by-Step Solution

1
Interpret the synovial fluid analysis.
The fluid shows 35,000 leukocytes/mm³ with rhomboid, weakly positively birefringent crystals and a negative Gram stain.
This confirms a diagnosis of acute calcium pyrophosphate dihydrate (CPPD) crystal deposition disease (pseudogout) and makes a diagnosis of septic arthritis highly unlikely.
2
Evaluate the patient's medical history for contraindications to standard therapies.
The patient has stage 3b chronic kidney disease, indicated by a serum creatinine of 2.3 mg/dL.
Standard first-line systemic therapies for acute crystal arthropathy, such as NSAIDs and colchicine, carry severe risks in the setting of renal failure.
3
Select the most appropriate, safest therapy for this specific patient.
Intra-articular glucocorticoid injection is chosen.
For monoarticular acute pseudogout in a patient with severe renal impairment, targeted intra-articular therapy provides rapid relief while entirely avoiding systemic renal and gastrointestinal toxicities.

Key Concept

Management of acute pseudogout (CPPD) in a patient with chronic kidney disease.
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Topics

Rheumatology and Immunology

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