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A 56-year-old man presents for evaluation in a primary care clinic. He has a 2-day history of right ankle swelling and pain. He reports experiencing discomfort with ambulation and when driving an automobile. On further questioning, he denies experiencing a recent trauma, although he does recall spraining his ankle approximately 10 years ago. On examination, the patient’s temperature is 99.9° F (37.7° C). His right ankle is warm to palpation and reveals an effusion. With passive range of motion of the right ankle, significant pain is elicited.
Which of the following is the most appropriate step to take next in the treatment of this patient?
A. Check the serum uric acid level; if elevated, initiate therapy with
indomethacin and colchicine
B. Obtain a plain radiograph of the right ankle to assess for structural
damage or chondrocalcinosis
C. Perform arthrocentesis of the right ankle, with analysis of the synovial
fluid
D. Treat with ibuprofen and have the patient return to clinic in 1 week if
his symptoms do not improve
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excellent c is the right answer, i will post explanation later
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In this patient, the acute onset of symptoms, low-grade fever, and lack of trauma warrant
a prompt evaluation; empirical therapy will not provide a definitive diagnosis and could
potentially result in a serious illness, such as septic arthritis, being missed. Joint aspiration
should be performed with aseptic technique as a part of the evaluation of every case of
acute monoarthritis. Analysis of the synovial fluid includes a WBC count and differential,
appropriate cultures and stains for microorganisms, and polarized-light microscopy. The
WBC count in the synovial fluid is useful in distinguishing inflammatory from noninflammatory
arthritis: levels greater than 2,000/mm3 are consistent with inflammation.
Patients with crystal-induced arthritis usually have counts in excess of 30,000/mm3. The
finding of monosodium urate or calcium pyrophosphate dihydrate crystals on polarizedlight
microscopy is pathognomonic for gout and pseudogout, respectively; the absence of
crystals does not exclude these diagnoses. The serum level of uric acid is of little use in
diagnosing gouty arthritis. Twenty percent of patients with gout have normal uric acid levels,
and most persons with elevated levels never develop gouty arthritis. Plain radiography
is most useful in patients with significant trauma that suggests the possibility of fracture,
in those who experience a sudden loss of function, and in those with symptoms that do
not improve despite appropriate treatment. This patient did not have any recent trauma
and was still able to bear weight (although it did cause pain). Chondrocalcinosis would
suggest the diagnosis of pseudogout, but the most appropriate initial evaluation of a
patient with a monoarticular arthritis is arthrocentesis. (Answer: C—Perform arthrocentesis of
the right ankle, with analysis of the synovial fluid
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Thanks sami2004, god bless you.
