A 45-year-old woman comes to the office with knee pain. She has a long history of rheumatoid arthritis affecting the joints of her hands, wrists, and knees. The patient has mild residual pain and joint stiffness on low-dose methotrexate but has otherwise done well. Over the past 2 days, the pain in her right knee has been much more severe and was associated with an episode of chills. Temperature is 38.7 C (101.6 F), blood pressure is 120/70 mm Hg, pulse is 100/min, and respirations are 18/min. Physical examination shows mild swelling in the joints of the hands and wrists. The right knee is red and more swollen than on previous examinations; active and passive range of motion at the right knee is limited due to pain. After appropriate diagnostic testing, which of the following is most likely to be indicated for this patient's current condition?

Question

A 45-year-old woman comes to the office with knee pain.  She has a long history of rheumatoid arthritis affecting the joints of her hands, wrists, and knees.  The patient has mild residual pain and joint stiffness on low-dose methotrexate but has otherwise done well.  Over the past 2 days, the pain in her right knee has been much more severe and was associated with an episode of chills.  Temperature is 38.7 C (101.6 F), blood pressure is 120/70 mm Hg, pulse is 100/min, and respirations are 18/min.  Physical examination shows mild swelling in the joints of the hands and wrists.  The right knee is red and more swollen than on previous examinations; active and passive range of motion at the right knee is limited due to pain.  After appropriate diagnostic testing, which of the following is most likely to be indicated for this patient's current condition?

Quizplus · Accepted Answer

11ec25c8_d524_ac3f_bc81_83a43ec41b72_MD0003_00 This patient's clinical features - acute monoarthritis with fever, limited range of motion, underlying rheumatoid arthritis (RA) - are suspicious for acute septic arthritis. Septic arthritis is more common in patients with underlying joint abnormalities (eg, RA, osteoarthritis), prosthetic joints, or those who undergo repeated synovial glucocorticoid injections. Patients with RA are at especially high risk due to impaired phagocytosis and systemic immunosuppression. Occasionally, septic arthritis in patients with underlying RA may present without overt signs of infection (eg, fever, chills, peripheral leukocytosis); this is especially common in elderly patients and may lead to a delayed diagnosis. Synovial fluid analysis should be performed to confirm the diagnosis and exclude other causes of acute inflammatory monoarthritis (eg, gout, pseudogout). Typical findings include elevated leukocytes (50,000-150,000/mm³), positive Gram stain, and positive fluid culture. Blood cultures are positive in 50% of patients and should be obtained along with synovial fluid studies prior to antibiotic therapy. Treatment of septic arthritis requires prompt administration of intravenous antibiotics and adequate joint drainage to lessen the likelihood of joint destruction. Gram stain (Choices A and D) Allopurinol decreases uric acid production by inhibiting xanthine oxidase and is used for the prevention of recurrent gout. Colchicine is indicated for treatment of acute gout, which may present as acute monoarthritis of the knee. However, gout attacks typically begin more abruptly and reach maximal severity within hours. Although fever may occur in gout, it is more common in septic arthritis, and this patient's underlying RA makes septic arthritis more likely. (Choices C and F) Biologic anticytokine agents (eg, infliximab, etanercept) are used for treatment of RA in patients who have failed first-line drugs. However, initiation of biologic agents is contraindicated during active infections, and the septic arthritis should be treated before adding additional antirheumatic agents or increasing the dose of this patient's current immunosuppressive regimen. RA flares typically involve multiple joints; acute inflammatory ("pseudoseptic") monoarthritis is uncommon and usually seen in patients with poorly controlled RA or in those who have recently discontinued antirheumatic therapy. (Choice E) Glucocorticoids may be considered for short-term treatment of RA. However, systemic glucocorticoids (eg, oral prednisone) or intra-articular glucocorticoids should be deferred until septic arthritis is excluded. Educational objective: Septic arthritis is characterized by acute monoarthritis, often with fever and restricted range of motion. It is more common in patients with underlying joint disease. Synovial fluid analysis should be performed promptly to confirm the diagnosis. References: Management of the nontraumatic hot swollen joint. (http://www.ncbi.nlm.nih.gov/pubmed/21730866) Approach to septic arthritis. (http://www.ncbi.nlm.nih.gov/pubmed/21916390)

A 45-Year-Old Woman Comes to the Office with Knee Pain