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Difficulty: MediumRheumatology and Immunology

An elderly man is evaluated on the surgical ward on postoperative day 3 following an elective sigmoid resection for diverticular disease. His medical history is significant for ischemic cardiomyopathy and stage 3a chronic kidney disease. Overnight, he developed acute, intense pain and marked swelling in his right knee. His temperature is 38.3°C (101.0°F), blood pressure is 132/82 mmHg, and pulse is 98/min. Physical examination of the right knee reveals significant erythema, warmth, and a large effusion. Passive range of motion is severely restricted by pain. Mild bilateral pitting edema is present at the ankles, which the patient states is his baseline. Arthrocentesis is performed, yielding synovial fluid with a leukocyte count of 35,000/μL (85% neutrophils). Microscopic analysis under polarized light reveals rhomboid-shaped crystals exhibiting weak positive birefringence. Gram stain of the fluid shows no organisms. Which of the following is the most appropriate next step in management?

  1. Administration of an intra-articular glucocorticoidAnswer
  2. B
    Initiation of intravenous vancomycin and ceftriaxone
  3. C
    Initiation of oral allopurinol
  4. D
    Initiation of intravenous furosemide
  5. E
    Computed tomography scan of the abdomen and pelvis

Answer

The most appropriate next step is the administration of an intra-articular glucocorticoid.
The patient is experiencing an acute flare of calcium pyrophosphate dihydrate (CPPD) crystal arthritis (pseudogout), confirmed by the synovial fluid demonstrating rhomboid, weakly positively birefringent crystals. Given his comorbidities of chronic kidney disease and ischemic cardiomyopathy, systemic NSAIDs are strongly contraindicated. Therefore, an intra-articular glucocorticoid injection is the safest and most effective targeted therapy for a monoarticular flare.

Step-by-Step Solution

1
Analyze the clinical presentation and synovial fluid findings.
The patient has an acute monoarticular inflammatory arthritis with rhomboid-shaped, positively birefringent crystals.
This establishes the primary diagnosis of calcium pyrophosphate dihydrate (CPPD) crystal deposition disease (pseudogout), which can be triggered by acute illness or surgery and present with low-grade fever.
2
Evaluate the patient's medical comorbidities.
The patient has stage 3a chronic kidney disease and ischemic cardiomyopathy.
Comorbidities dictate the safety profile of acute therapies. Systemic NSAIDs are contraindicated in CKD and heart failure.
3
Select the optimal pharmacotherapy for the acute flare.
Administration of an intra-articular glucocorticoid is selected.
It provides highly effective, targeted relief for a single inflamed joint while avoiding the systemic adverse effects associated with NSAIDs or colchicine in a patient with renal and cardiac impairment.

Key Concept

Diagnosis and management of acute calcium pyrophosphate dihydrate (CPPD) crystal arthritis (pseudogout) in patients with contraindications to NSAIDs.
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Topics

Rheumatology and Immunology

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