Stepwise model may improve diagnosis of periprosthetic joint infections
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When diagnosing periprosthetic joint infections, physicians should follow a stepwise model, using available resources within the practice or hospital, according to a presenter at the Current Concepts of Joint Replacement Spring Meeting.
“As physicians, we always start with history and physical exam. How long have they had infectious symptoms for?” Antonia F. Chen, MD, said in her presentation. “These symptoms include fever, chills, pain with range of motion, sudden change in pain and wound drainage.”
Next, physicians should collect erythrocyte sedimentation rate and C-reactive protein levels, followed by synovial fluid aspiration sent for white cell count, neutrophil differential, crystals and culture, according to Chen. Although cultures have a low sensitivity, Chen noted physicians can improve culture yield by taking patients off antibiotics for 2 weeks and sending the fluid in pediatric blood culture vials. She also recommended physicians avoid swabs and gram stains.
“If you go to the operating room, either for an open biopsy or for a procedure, get tissue cultures, get larger sample sizes, an odd number so it becomes a tie breaker, hold your cultures for 14 days and then do fungal and tuberculosis cultures for 6 weeks,” Chen said. “In different parts of the world, these are more likely to be positive in various scenarios, so the 6 weeks becomes key.”
If a patient has equivocal results based on the Musculoskeletal Infection Society definition of periprosthetic joint infection, she noted physicians can test biomarkers, including alpha-defensin, leukocyte esterase, D-dimer, synovial fluid C-reactive protein and procalcitonin or interleukin-6.
“When it comes to imaging, there are X-rays, and we always follow this for implant loosening, which can change your ability to do a two-stage or one-stage [procedure] or an [irrigation and debridement] I&D and polyethylene exchange,” Chen said. “People sometimes get CT scans and MRIs. They are not as useful, but tagged white blood cell scans can actually be useful in some select cases.”
Reference:
Chen AF. Paper 36. Presented at: Current Concepts in Joint Replacement Spring Meeting; May 18-20, 2020 (virtual meeting).
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Chen AF. Paper 36. Presented at: Current Concepts of Joint Replacement Spring Meeting; May 18-20, 2020 (virtual meeting).
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