A 64-year-old man comes to the emergency department with a 3-day history of progressively increasing pain, swelling, and redness of his right knee. The pain is severe with weight bearing, and he is unable to ambulate without assistance. The patient reports no recent trauma to the knee but has had subjective fever. He was diagnosed with gout 10 years ago and had several recurrences of acute gout involving multiple joints, but has had good control since he started taking allopurinol. Six weeks ago, he went on a camping trip in the mountains of New Hampshire. Medical history is notable for type 2 diabetes mellitus and hypertension. Current medications include lisinopril and metformin. The patient does not use tobacco, alcohol, or illicit drugs. His temperature is 38.3 C (100.9 F), blood pressure is 110/65 mm Hg, and pulse is 110/min. Examination shows a tender, swollen, erythematous right knee with markedly decreased range of motion. The remainder of the examination is unremarkable. Which of the following is the most appropriate next step in management?

Question

A 64-year-old man comes to the emergency department with a 3-day history of progressively increasing pain, swelling, and redness of his right knee.  The pain is severe with weight bearing, and he is unable to ambulate without assistance.  The patient reports no recent trauma to the knee but has had subjective fever.  He was diagnosed with gout 10 years ago and had several recurrences of acute gout involving multiple joints, but has had good control since he started taking allopurinol.  Six weeks ago, he went on a camping trip in the mountains of New Hampshire.  Medical history is notable for type 2 diabetes mellitus and hypertension.  Current medications include lisinopril and metformin.  The patient does not use tobacco, alcohol, or illicit drugs.  His temperature is 38.3 C (100.9 F), blood pressure is 110/65 mm Hg, and pulse is 110/min.  Examination shows a tender, swollen, erythematous right knee with markedly decreased range of motion.  The remainder of the examination is unremarkable.  Which of the following is the most appropriate next step in management?

Quizplus · Accepted Answer

This patient's presentation with fever and acute monoarticular arthritis warrants urgent synovial fluid analysis (cell count, Gram stain, culture) to exclude septic arthritis. Patients with an established diagnosis of gout who have typical symptoms of a flare can be managed without joint aspiration. Although gout can cause low-grade fever, the progressive nature of this patient's symptoms over 3 days (gout flares typically have an abrupt onset with maximal symptoms within 12-24 hours) increases the likelihood of a septic joint, particularly in the setting of diabetes. Underlying joint disorders (eg, gout, pseudogout, osteoarthritis) increase the risk for secondary joint infection. In patients with crystal-induced arthritis (eg, gout), the presence of crystals alone does not rule out septic arthritis as these can be present in synovial fluid between attacks. If the Gram stain is positive and joint fluid white cell count is >50,000/mm³, the patient should be started on empiric antibiotics until culture results are known. If crystals are present, the fluid is nonpurulent, and Gram stain is negative, the patient may be managed as for a standard gout flare (Choice C). (Choice A) Although this patient's recent travel places him at risk for Lyme disease, Lyme arthritis usually develops months after initial infection. Regardless, septic arthritis should be excluded first. (Choice B) MRI is useful to evaluate soft-tissue structures in the knee (eg, meniscus, ligaments) but is not usually needed to evaluate acute arthritis, especially in a patient with no history of trauma. (Choice D) The serum uric acid level is useful in assessing the effectiveness of urate-lowering therapy in chronic gout. It is less useful in evaluating acute arthritis and is often normal during an acute gout attack. (Choice F) X-ray is useful if a fracture, pseudogout (chondrocalcinosis), or osteoarthritis (narrow joint space, osteophytes) is suspected. However, ruling out septic arthritis is a higher priority. Educational objective: Synovial fluid should be obtained urgently for cell count, Gram stain, and culture in any patient with possible septic arthritis. Preexisting joint disorders can increase the risk for secondary infection of the joint. In patients with crystal-induced arthritis (eg, gout), the presence of crystals in the synovial fluid does not rule out septic arthritis as these will be present between attacks.

A 64-Year-Old Man Comes to the Emergency Department with a 3-Day