title: Serological markers can lead to false negative diagnoses of periprosthetic infections following total knee arthroplasty.
abstract: Periprosthetic infections following total knee arthroplasty (TKA) are diagnostically challenging. We evaluated the sensitivity and specificity of ESR and CRP, false negative rates, whether false negative rates differed between early post-operative and late infections, and the predictive ability of ESR and CRP to differentiate infected patients. Between 2000 and 2007, a prospectively collected database was reviewed to identify patients with suspected periprosthetic infections, and who had ESR and CRP laboratory values. One hundred and thirteen patients were identified. False negative rates were calculated. Finally, receiver operating characteristic curves were used to determine the predictive ability of ESR and CRP to differentiate infected from non-infected patients. CRP had a sensitivity of 95% and specificity of 20%. ESR had a sensitivity of 91% and a specificity of 33%. The false negative rate was 9.2% for ESR, 5.3% for CRP, and 11.1% for combined ESR and CRP. False negative rates were higher for early post-operative infections. Although ESR and CRP can be excellent adjunctive diagnostic tools, we emphasise that because some patients may not mount a sufficient immune response, the entire clinical picture must be evaluated, and periprosthetic infection should not be ruled out on the basis of ESR and CRP results alone.
authors.affiliation: Rubin Institute for Advanced Orthopedics, Center for Joint Preservation and Reconstruction, Sinai Hospital of Baltimore, Baltimore, MD 21215, USA.
authors.forename: Aaron J
authors.initials: AJ
authors.lastname: Johnson
authors.forename: Michael G
authors.initials: MG
authors.lastname: Zywiel
authors.forename: Alex
authors.initials: A
authors.lastname: Stroh
authors.forename: David R
authors.initials: DR
authors.lastname: Marker
authors.forename: Michael A
authors.initials: MA
authors.lastname: Mont
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D019645:Arthroplasty, Replacement, Knee / Q000009:adverse effects*; D015415:Biomarkers / Q000097:blood; D001799:Blood Sedimentation; D002097:C-Reactive Protein / Q000032:analysis; D016208:Databases, Factual; D003951:Diagnostic Errors; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D011446:Prospective Studies; D016459:Prosthesis-Related Infections / Q000097:blood / Q000175:diagnosis*
chemical_list: D015415:Biomarkers; D002097:C-Reactive Protein