Background Periprosthetic joint infection is a serious complication after THA and commonly is treated with a two-stage revision. Antibiotic-eluting cement spacers are placed for local delivery of antibiotics. Aspirations may be performed before the second-stage reimplantation for identification of persistent infection. However, limited data exist regarding the diagnostic parameters of synovial fluid aspiration with or without saline lavage from a hip with an antibiotic-loaded cement spacer. Questions/purposes We asked: (1) For hips with antibiotic cement spacers, does saline lavage influence the diagnostic validity of aspirations? (2) What is the diagnostic accuracy of preoperative aspirations performed on hips with antibiotic cement spacers using the Musculoskeletal Infection Society (MSIS) criteria, stratified by saline and nonlavage? (3) For hips with antibiotic spacers, what are the optimal thresholds for synovial fluid white blood cell (WBC) count and polymorphonuclear neutrophil (PMN) percentage for diagnosing infections? Methods One hundred seventy-four hips (155 patients) with antibiotic-eluting cement spacers inserted between October 2012 and July 2015 were reviewed. Of these, 98 hips (80 patients) met the inclusion criteria and were included in the analysis (77 nonlavage, 21 saline lavage aspirations). Laboratory data from the aspiration and preoperative workup and intraoperative details were collected. Infection status of each hip procedure was determined One of the authors certifies that he (WKB), or a member of his immediate family, has or may receive payments or benefits, during the study period an amount of USD 100,001 to USD 1,000,000 from Stryker (Kalamazoo, MI, USA); an amount of USD 100,001 to USD 1,000,000 from Exactech (Gainesville, FL, USA); an amount of less than USD 10,000 from Zimmer (Warsaw, IN, USA); an amount of less than USD 10,000 from Custom Orthopaedic Solutions (Cleveland, OH, USA; an amount of USD 100,001 to USD 1,000,000 from KEF Healthcare (Westminster, CO, USA); amount of less than USD 10,000 from iVHR (Cleveland, OH, USA); an amount of less than USD 10,000 from PeerWell (San Francisco, CA, USA), and has received research support from Zimmer (Warsaw, IN, USA), DJO (Vista, CA, USA), and Orthosensor (Dania Beach, FL, USA). One of the authors (CAH) or a member of his immediate family, has or may receive payments or benefits, during the study period, an amount of less than USD 10,000 from KCI (San Antonio, TX, USA); an amount of less than USD 10,000 from Zimmer Biomet (Warsaw, IN, USA); an amount of less than USD 10,000 from Covance (Princeton, NJ, USA); an amount of less than USD 10,000 from Pfizer (New York, NY, USA); and has received research support funding from Stryker (Kalamazoo, MI, USA), Myoscience (Fresno, CA, USA), CD Diagnostics (Claymont, DE, USA), KCI (San Antonio, TX, USA), OREF (Rosemont, IL, USA), and Pacira (Parsippany, NJ, USA).
All ICMJE Conflict of Interest Forms for authors and Clinical Orthopaedics and Related Research1 editors and board members are ...