A 27-year-old man comes to the emergency department due to severe left knee pain and swelling for the past 2 days. He has no recent injury or significant medical problems. The patient drinks 3 or 4 cans of beer daily but does not use tobacco or illicit drugs. He works as a groundskeeper at a nearby golf course and has had to take the last couple of days off because of the pain. Temperature is 38.3 C (101 F), blood pressure is 115/70 mm Hg, and pulse is 92/min. On examination, the left knee is swollen, erythematous, warm, and tender with restricted range of active and passive motion. The remainder of the examination is unremarkable. Which of the following is the best next step in management of this patient?

Question

A 27-year-old man comes to the emergency department due to severe left knee pain and swelling for the past 2 days.  He has no recent injury or significant medical problems.  The patient drinks 3 or 4 cans of beer daily but does not use tobacco or illicit drugs.  He works as a groundskeeper at a nearby golf course and has had to take the last couple of days off because of the pain.  Temperature is 38.3 C (101 F), blood pressure is 115/70 mm Hg, and pulse is 92/min.  On examination, the left knee is swollen, erythematous, warm, and tender with restricted range of active and passive motion.  The remainder of the examination is unremarkable.  Which of the following is the best next step in management of this patient?

Quizplus · Accepted Answer

This patient has acute joint pain, swelling, and erythema with restricted range of motion, consistent with synovitis. Acute undiagnosed synovitis, especially when accompanied by fever or leukocytosis, represents a true emergency and warrants an expedited evaluation. Potential causes include septic arthritis (gonococcal, nongonococcal), crystal arthropathy (eg, gout), hemarthrosis, or rheumatic disease. Delayed diagnosis of septic arthritis may lead to loss of the joint and long-term disability, and may be fatal (Choice A). Acute synovitis is best evaluated with diagnostic arthrocentesis and synovial fluid analysis. Gross inspection may assist the diagnosis, with purulent or cloudy fluid suggesting an infectious or inflammatory process. Fluid should be sent for crystal analysis, cell count, Gram stain, and culture. Blood cultures should also be drawn if septic arthritis is suspected. (Choice B) MRI is useful to evaluate menisci, ligaments, and other soft tissues around the joint. However, MRI can be time-consuming and would not provide a definitive diagnosis of septic arthritis. (Choice C) Radionuclide bone scans are useful in the evaluation of metastatic and infectious bone disorders. However, the findings are sensitive but very nonspecific for potential causes of synovitis. (Choice D) Synovial fluid crystal analysis is the definitive test for gout. Serum uric acid levels are less useful for diagnosis and may be normal during an acute gout attack. In addition, serum uric acid levels do not rule out other important causes of synovitis such as septic arthritis. Educational objective: Synovitis is characterized by pain, erythema, swelling, and reduced range of motion in a joint. Acute synovitis may represent serious pathology (eg, septic arthritis), especially if accompanied by fever or leukocytosis; it should be evaluated urgently with synovial fluid analysis. __________ References: Septic arthritis: current diagnostic and therapeutic algorithm. (http://www.ncbi.nlm.nih.gov/pubmed/18525361)

A 27-Year-Old Man Comes to the Emergency Department Due to Severe