title: C-reactive protein, erythrocyte sedimentation rate and orthopedic implant infection.
abstract: BACKGROUND
  C-reactive protein (CRP) and erythrocyte sedimentation rate (ESR) have been shown to be useful for diagnosis of prosthetic hip and knee infection. Little information is available on CRP and ESR in patients undergoing revision or resection of shoulder arthroplasties or spine implants.
  
  
  RESULTS
  We analyzed preoperative CRP and ESR in 636 subjects who underwent knee (n=297), hip (n=221) or shoulder (n=64) arthroplasty, or spine implant (n=54) removal. A standardized definition of orthopedic implant-associated infection was applied. Receiver operating curve analysis was used to determine ideal cutoff values for differentiating infected from non-infected cases. ESR was significantly different in subjects with aseptic failure infection of knee (median 11 and 53.5 mm/h, respectively, p=<0.0001) and hip (median 11 and 30 mm/h, respectively, p=<0.0001) arthroplasties and spine implants (median 10 and 48.5 mm/h, respectively, p=0.0033), but not shoulder arthroplasties (median 10 and 9 mm/h, respectively, p=0.9883). Optimized ESR cutoffs for knee, hip and shoulder arthroplasties and spine implants were 19, 13, 26, and 45 mm/h, respectively. Using these cutoffs, sensitivity and specificity to detect infection were 89 and 74% for knee, 82 and 60% for hip, and 32 and 93% for shoulder arthroplasties, and 57 and 90% for spine implants. CRP was significantly different in subjects with aseptic failure and infection of knee (median 4 and 51 mg/l, respectively, p<0.0001), hip (median 3 and 18 mg/l, respectively, p<0.0001), and shoulder (median 3 and 10 mg/l, respectively, p=0.01) arthroplasties, and spine implants (median 3 and 20 mg/l, respectively, p=0.0011). Optimized CRP cutoffs for knee, hip, and shoulder arthroplasties, and spine implants were 14.5, 10.3, 7, and 4.6 mg/l, respectively. Using these cutoffs, sensitivity and specificity to detect infection were 79 and 88% for knee, 74 and 79% for hip, and 63 and 73% for shoulder arthroplasties, and 79 and 68% for spine implants.
  
  
  CONCLUSIONS
  CRP and ESR have poor sensitivity for the diagnosis of shoulder implant infection. A CRP of 4.6 mg/l had a sensitivity of 79 and a specificity of 68% to detect infection of spine implants.
authors.affiliation: Division of Infectious Diseases, Department of Medicine, Mayo Clinic College of Medicine, Rochester, Minnesota, United States of America.
authors.forename: Kerryl E
authors.initials: KE
authors.lastname: Piper
authors.forename: Marta
authors.initials: M
authors.lastname: Fernandez-Sampedro
authors.forename: Kathryn E
authors.initials: KE
authors.lastname: Steckelberg
authors.forename: Jayawant N
authors.initials: JN
authors.lastname: Mandrekar
authors.forename: Melissa J
authors.initials: MJ
authors.lastname: Karau
authors.forename: James M
authors.initials: JM
authors.lastname: Steckelberg
authors.forename: Elie F
authors.initials: EF
authors.lastname: Berbari
authors.forename: Douglas R
authors.initials: DR
authors.lastname: Osmon
authors.forename: Arlen D
authors.initials: AD
authors.lastname: Hanssen
authors.forename: David G
authors.initials: DG
authors.lastname: Lewallen
authors.forename: Robert H
authors.initials: RH
authors.lastname: Cofield
authors.forename: John W
authors.initials: JW
authors.lastname: Sperling
authors.forename: Joaquin
authors.initials: J
authors.lastname: Sanchez-Sotelo
authors.forename: Paul M
authors.initials: PM
authors.lastname: Huddleston
authors.forename: Mark B
authors.initials: MB
authors.lastname: Dekutoski
authors.forename: Michael
authors.initials: M
authors.lastname: Yaszemski
authors.forename: Bradford
authors.initials: B
authors.lastname: Currier
authors.forename: Robin
authors.initials: R
authors.lastname: Patel
mesh_terms: D001178:Arthroplasty / Q000009:adverse effects; D019644:Arthroplasty, Replacement, Hip / Q000009:adverse effects; D001799:Blood Sedimentation; D002097:C-Reactive Protein / Q000032:analysis*; D006801:Humans; D007720:Knee Prosthesis / Q000009:adverse effects; D016015:Logistic Models; D019736:Prostheses and Implants / Q000009:adverse effects*; D016459:Prosthesis-Related Infections / Q000097:blood* / Q000175:diagnosis* / Q000209:etiology; D012680:Sensitivity and Specificity; D012785:Shoulder Joint / Q000601:surgery
chemical_list: D002097:C-Reactive Protein