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Resident
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Internal Medicine
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Resident
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Internal Medicine
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Resident
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Internal Medicine
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Internal Medicine
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Orthopedic Surgery
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Patient Care
Abstract
Introduction: Pseudoseptic arthritis is the umbrella term designated to various mimics when they present with clinical stigmata indicative of septic arthritis. The underlying causes of these mimics can vary, depending on whether they are associated with autoimmune inflammatory arthritis or crystalline-associated inflammatory arthritis such as gout and calcium pyrophosphate deposition disease (CPPD). In clinical practice, pseudoseptic arthritis can be difficult to differentiate from infectious arthritis, leading to frequent misdiagnosis. However, key differences will exist in the joint aspirate. With septic arthritis, the synovial fluid cultures are positive. However, with pseudoseptic arthritis, the synovial fluid may appear purulent but is sterile. Join fluid analysis is crucial as septic arthritis is an orthopedic emergency that can cause significant joint damage and further sequelae. Despite antibiotic therapy, there remains a 7% to 15% mortality rate.
Case presentation: An 86-year-old man with a complex past medical history, including gout, amyloid heart disease, atrial fibrillation, and chronic kidney disease stage IV, presented to the emergency department with worsening left knee pain and swelling over the past five days. The day previous admission he was seen in an outpatient setting and underwent left knee arthrocentesis. Due to lack of symptomatic improvement, the patient decided to visit the emergency department.
Upon arrival, the patient endorsed chills and malaise. Denied any recent trauma to the knee or recent joint injections but did report a history of partial left knee replacement in 2011. The patient's vital signs were stable and unremarkable. On physical examination, the left knee was warm to the touch with significant swelling and had painful passive and active range of motion.
Laboratory findings on admission revealed an elevated sedimentation rate of 61 mm/hr (reference range 2-10 mm/hr.). White blood cell count, and hemoglobin were within normal limits. Left knee X-ray demonstrated moderate suprapatellar effusion. The patient was admitted for suspected septic arthritis versus gout flare and underwent arthroscopic lavage of the affected knee. The fluid analysis obtained during arthroscopy revealed the presence of calcium pyrophosphate crystals, consistent with pseudogout. Additionally, the WBC count was markedly elevated >50,000. Empiric antibiotic therapy with daptomycin and ceftriaxone was initiated while awaiting the results of the fluid and blood cultures, which resulted negative.
Fluid analysis collected via arthrocentesis on the day prior to admission revealed similar findings, characterized by the presence of pseudogout. Once again, on fluid analysis despite the markedly elevated WBC count >100,000, fluid cultures returned negative.
Peripheral access for antibiotics was placed, and the patient was discharged to an acute rehabilitation center to complete ten days of antibiotic treatment.
Discussion: The case discussed highlights the difficulties clinicians face when differentiating between septic arthritis and pseudoseptic arthritis, especially in patients who have history of gout, and fluid analysis showing significantly increased white blood cell count.
Before confirming a diagnosis of pseudoseptic arthritis, it is crucial to rule out septic arthritis, which is the more severe and potentially life-threatening condition. A joint with purulent fluid should be presumed to be septic until proven otherwise. Conversely, pseudoseptic arthritis also requires an accurate diagnosis, supported by thorough joint fluid analysis and culture. Awareness of pseudoseptic arthritis is important for preventing misdiagnosis, optimizing patient outcomes, and ensuring judicious use of antibiotics.
This presentation is challenging due to the presence of high WBC count in the joint fluid, presence of crystals, and consistently negative cultures. Given the presentation and elevated risk, antibiotics were continued, although it remains uncertain whether the patient's condition would improve similarly with or without them. Opting not to treat with antibiotics becomes more straightforward if a patient has experienced previous episodes of arthritis without identifiable cultures, is not immunosuppressed, or does not have any concurrent infections.
This case highlights the importance of a multidisciplinary approach involving orthopedics, internal medicine physicians, infectious disease specialists, and physical therapists to optimize patient outcomes and preserve joint function.
Presentation Type
Poster
Recommended Citation
Durazo, Yareli; Haines, Corey; Gonzalez, Elimar; Cantazaro, Brandon; and Sander, Michael, "Pseudogout: A Rare Cause of Pseudoseptic Arthritis - A Case Report" (2024). Research Colloquium. 39.
https://scholarworks.utrgv.edu/colloquium/2024/posters/39
Included in
Pseudogout: A Rare Cause of Pseudoseptic Arthritis - A Case Report
Introduction: Pseudoseptic arthritis is the umbrella term designated to various mimics when they present with clinical stigmata indicative of septic arthritis. The underlying causes of these mimics can vary, depending on whether they are associated with autoimmune inflammatory arthritis or crystalline-associated inflammatory arthritis such as gout and calcium pyrophosphate deposition disease (CPPD). In clinical practice, pseudoseptic arthritis can be difficult to differentiate from infectious arthritis, leading to frequent misdiagnosis. However, key differences will exist in the joint aspirate. With septic arthritis, the synovial fluid cultures are positive. However, with pseudoseptic arthritis, the synovial fluid may appear purulent but is sterile. Join fluid analysis is crucial as septic arthritis is an orthopedic emergency that can cause significant joint damage and further sequelae. Despite antibiotic therapy, there remains a 7% to 15% mortality rate.
Case presentation: An 86-year-old man with a complex past medical history, including gout, amyloid heart disease, atrial fibrillation, and chronic kidney disease stage IV, presented to the emergency department with worsening left knee pain and swelling over the past five days. The day previous admission he was seen in an outpatient setting and underwent left knee arthrocentesis. Due to lack of symptomatic improvement, the patient decided to visit the emergency department.
Upon arrival, the patient endorsed chills and malaise. Denied any recent trauma to the knee or recent joint injections but did report a history of partial left knee replacement in 2011. The patient's vital signs were stable and unremarkable. On physical examination, the left knee was warm to the touch with significant swelling and had painful passive and active range of motion.
Laboratory findings on admission revealed an elevated sedimentation rate of 61 mm/hr (reference range 2-10 mm/hr.). White blood cell count, and hemoglobin were within normal limits. Left knee X-ray demonstrated moderate suprapatellar effusion. The patient was admitted for suspected septic arthritis versus gout flare and underwent arthroscopic lavage of the affected knee. The fluid analysis obtained during arthroscopy revealed the presence of calcium pyrophosphate crystals, consistent with pseudogout. Additionally, the WBC count was markedly elevated >50,000. Empiric antibiotic therapy with daptomycin and ceftriaxone was initiated while awaiting the results of the fluid and blood cultures, which resulted negative.
Fluid analysis collected via arthrocentesis on the day prior to admission revealed similar findings, characterized by the presence of pseudogout. Once again, on fluid analysis despite the markedly elevated WBC count >100,000, fluid cultures returned negative.
Peripheral access for antibiotics was placed, and the patient was discharged to an acute rehabilitation center to complete ten days of antibiotic treatment.
Discussion: The case discussed highlights the difficulties clinicians face when differentiating between septic arthritis and pseudoseptic arthritis, especially in patients who have history of gout, and fluid analysis showing significantly increased white blood cell count.
Before confirming a diagnosis of pseudoseptic arthritis, it is crucial to rule out septic arthritis, which is the more severe and potentially life-threatening condition. A joint with purulent fluid should be presumed to be septic until proven otherwise. Conversely, pseudoseptic arthritis also requires an accurate diagnosis, supported by thorough joint fluid analysis and culture. Awareness of pseudoseptic arthritis is important for preventing misdiagnosis, optimizing patient outcomes, and ensuring judicious use of antibiotics.
This presentation is challenging due to the presence of high WBC count in the joint fluid, presence of crystals, and consistently negative cultures. Given the presentation and elevated risk, antibiotics were continued, although it remains uncertain whether the patient's condition would improve similarly with or without them. Opting not to treat with antibiotics becomes more straightforward if a patient has experienced previous episodes of arthritis without identifiable cultures, is not immunosuppressed, or does not have any concurrent infections.
This case highlights the importance of a multidisciplinary approach involving orthopedics, internal medicine physicians, infectious disease specialists, and physical therapists to optimize patient outcomes and preserve joint function.