title: Elevated high-sensitivity C-reactive protein levels are associated with local inflammatory findings in patients with osteoarthritis.
abstract: OBJECTIVE
  C-reactive protein (CRP) has been associated with disease progression in patients with osteoarthritis (OA), but the reasons for this remain unclear. We hypothesized that higher CRP would be related to local inflammatory findings in the joints of patients with OA.
  
  
  METHODS
  Plasma and synovial membrane specimens from 54 OA patients undergoing total hip or knee arthroplasty or arthroscopy were obtained. Synovial fluid was obtained from 25 of these patients. Hematoxylin and eosin stained synovial membrane sections were scored for degree of inflammatory cell infiltration. Plasma high-sensitivity CRP (hsCRP) levels, and serum and synovial fluid interleukin (IL)-6 and IL-1beta levels were measured by enzyme-linked immunosorbent assay.
  
  
  RESULTS
  Fifty-seven percent of patients with idiopathic OA had inflammatory infiltrates within the synovial membrane. The mean hsCRP level in patients with inflammatory infiltrates was significantly higher than those without inflammation (4.7 +/- 5.0 mg/L vs 1.7 +/- 3.6 mg/L, P = 0.003). There were significant correlations between hsCRP levels and synovial fluid IL-6 (r = 0.64, P = 0.0006), degree of synovial inflammatory infiltration (r = 0.43, P = 0.002), and body mass index (r = 0.31, P = 0.02). Multivariate analysis indicated that only degree of inflammatory infiltrate was significantly associated with hsCRP level (P = 0.026).
  
  
  CONCLUSIONS
  These results suggest that systemic hsCRP levels reflect synovial inflammation in OA patients, perhaps by means of synovial IL-6 production. Future studies are needed to clarify how these infiltrates and their products may contribute to disease pathogenesis.
authors.affiliation: Department of Orthopedic Surgery, Hospital for Special Surgery, New York, NY 10021, USA.
authors.forename: A D
authors.initials: AD
authors.lastname: Pearle
authors.forename: C R
authors.initials: CR
authors.lastname: Scanzello
authors.forename: S
authors.initials: S
authors.lastname: George
authors.forename: L A
authors.initials: LA
authors.lastname: Mandl
authors.forename: E F
authors.initials: EF
authors.lastname: DiCarlo
authors.forename: M
authors.initials: M
authors.lastname: Peterson
authors.forename: T P
authors.initials: TP
authors.lastname: Sculco
authors.forename: M K
authors.initials: MK
authors.lastname: Crow
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D019644:Arthroplasty, Replacement, Hip; D019645:Arthroplasty, Replacement, Knee; D001182:Arthroscopy; D002097:C-Reactive Protein / Q000032:analysis*; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D053583:Interleukin-1beta / Q000032:analysis* / Q000097:blood; D015850:Interleukin-6 / Q000032:analysis* / Q000097:blood; D008297:Male; D008875:Middle Aged; D015207:Osteoarthritis, Hip / Q000097:blood / Q000378:metabolism*; D020370:Osteoarthritis, Knee / Q000097:blood / Q000378:metabolism*; D013582:Synovial Fluid / Q000737:chemistry*
chemical_list: D053583:Interleukin-1beta; D015850:Interleukin-6; D002097:C-Reactive Protein