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Difficulty: MediumRheumatology and Immunology

A 74-year-old man is evaluated in the outpatient clinic due to a 24-hour history of exquisite right knee pain, swelling, and difficulty bearing weight. His medical history is significant for ischemic cardiomyopathy with a left ventricular ejection fraction of 30%, chronic kidney disease with a baseline serum creatinine of 2.1 mg/dL, and bilateral knee osteoarthritis. Current medications include carvedilol, lisinopril, furosemide, and low-dose aspirin. Vital signs are temperature 37.5°C (99.5°F), blood pressure 110/70 mmHg, heart rate 82/min, and respiratory rate 14/min. Physical examination reveals a markedly swollen, erythematous, and warm right knee with a palpable effusion. Arthrocentesis is performed, yielding turbid synovial fluid. Synovial fluid analysis shows a leukocyte count of 22,000/mm³ (75% neutrophils). Gram stain of the fluid shows no organisms. Polarized light microscopy demonstrates rhomboid-shaped crystals with weak positive birefringence. Which of the following is the most appropriate next step in management?

  1. Intra-articular triamcinolone injectionAnswer
  2. B
    Intravenous vancomycin and ceftriaxone
  3. C
    Oral indomethacin
  4. D
    Oral allopurinol
  5. E
    Serum antinuclear antibody testing

Answer

Intra-articular triamcinolone injection
This patient is experiencing an acute monoarticular arthritis. The synovial fluid analysis—specifically the identification of rhomboid-shaped, weakly positively birefringent crystals—is diagnostic of an acute flare of calcium pyrophosphate deposition (CPPD) disease, or pseudogout. First-line treatments for acute pseudogout include NSAIDs, colchicine, and intra-articular glucocorticoids. Because this patient has a history of ischemic cardiomyopathy with a severely reduced ejection fraction and underlying chronic kidney disease, systemic therapies like NSAIDs are contraindicated due to the risk of precipitating acute decompensated heart failure and worsening renal impairment. High-dose colchicine is similarly hazardous in advanced renal disease. Therefore, an intra-articular glucocorticoid injection is the safest and most appropriate next step in management to resolve the local inflammation without causing systemic toxicity.

Step-by-Step Solution

1
Interpret the synovial fluid analysis findings.
The presence of a moderate leukocyte count (22,000/mm³) and rhomboid-shaped, weakly positively birefringent crystals confirms the diagnosis of acute calcium pyrophosphate deposition (CPPD) disease, commonly known as pseudogout.
Accurate differentiation between crystal arthropathies and infectious arthritis dictates the entire management pathway.
2
Evaluate the patient's medical history for contraindications to standard therapies.
The patient has severe ischemic cardiomyopathy (ejection fraction 30%) and chronic kidney disease, which strongly contraindicate the use of systemic nonsteroidal anti-inflammatory drugs (NSAIDs) and systemic colchicine.
Standard first-line systemic treatments for crystal arthritis can precipitate life-threatening organ failure in vulnerable patients.
3
Select the safest, most effective localized therapy.
Intra-articular glucocorticoid injection (such as triamcinolone) is chosen.
It provides excellent local anti-inflammatory effects for a monoarticular flare while avoiding the systemic adverse effects associated with oral medications.

Key Concept

In patients presenting with an acute monoarticular flare of pseudogout (CPPD) who have major contraindications to NSAIDs and colchicine (such as severe heart failure and chronic kidney disease), intra-articular glucocorticoid injection is the safest and most appropriate initial treatment.
Estimated Time:1m 0s
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Topics

Rheumatology and Immunology

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