Synovial fluid tests with leukocyte esterase strips improved periprosthetic joint infection detection

  • Orthopaedics Today Europe [Archives], Issue 2

SAN FRANCISCO — A prospective cohort study showed that leukocyte esterase reagent strips can play an important role in the rapid diagnosis of periprosthetic joint infection when following patients after total joint arthroplasty.

The study built on previous work done by Javad Parvizi, MD, FRCS, director of research at the Rothman Institute and professor of orthopedics at Jefferson Medical College, in Philadelphia, and fellow researchers, to develop a better, faster way to diagnose PJI.

“LE [leukocyte esterase] is a very accurate test for diagnosing PJI [periprosthetic joint infection],” Parvizi said at the American Academy of Orthopaedic Surgeons 2012 Annual Meeting, here.

The need for a reliable test for PJI was considerable. All the tests previously available combined did not approach the sensitivity and specificity of the LE dip stick test, which has long been used to diagnose urinary tract infections, he noted. Parvizi said the strips detect the presence of the LE enzyme, which is produced by neutrophils that are present when there is an infection.

“LE at 2-plus had 100% positive predictive value and 100% specificity. I am not aware of a single test in our armamentarium today that carries the same specificity and positive predictive value,” he said, noting the strips, which are commercially available, cost about 25 cents each and can detect PJI in about 1 minute.

At 1-plus the specificity and sensitivity of the LE dip stick test is about 96% and 97%, respectively, based on the findings.

“Our continued research will help us get to the root cause of PJI and therefore enable us to diagnose this terrible condition expeditiously, inexpensively, and with minimal risk to patients,” Parvizi stated in a press release from Jefferson Medical College.

The team used the LE strips in 288 revision total joint arthroplasties, but Parvizi only presented results for 129 revision total knee arthroplasty cases at the meeting. They excluded all cases with bloody aspirate samples because blood affects the colorimetric strips.

Reference:
  • Ghanem ES, Adeli B, Parvizi J. Diagnosis of periprosthetic infection: further results on Leukocyte esterase dip stick test. Paper #33. Presented at the American Academy of Orthopaedic Surgeons 2012 Annual Meeting. Feb. 7-11. San Francisco.
  • Disclosure: Parvizi is a paid consultant to Biomet, Covidien, NIH, Salient Surgical, Smith & Nephew, Stryker, TissueGene and Zimmer. He receives research/institutional support from 3M, Musculoskeletal Transplant Foundation, NIH, Stryker and Zimmer and receives royalties/material support from Saunders/Mosby-Elsevier, SLACK Incorproated, Wolters, Kluwer Health Lippincott Williams & Wilkins.

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