title: Inflammatory predictors of ongoing pain 2 years following knee replacement surgery.
abstract: BACKGROUND
  The prevalence of unrelieved pain following total knee arthroplasty (TKA) is substantial.
  
  
  OBJECTIVE
  We asked if cytokine markers of inflammation in preoperative serum or knee synovial fluid (SF) would predict pain 2 years following TKA.
  
  
  METHODS
  Demographic data and functional outcomes were recorded at baseline and 2 years with the WOMAC index. Serum and SF tissue samples were collected at the time of surgery. Linear regression modeling was used to determine the relationship between SF/serum inflammatory markers and a lesser improvement in self reported pain at two years follow-up.
  
  
  RESULTS
  Of our 28 patient cohort, significant correlations between serum and SF levels were found for IL-1β (p<0.002), MIP-1β (p<0.001), adiponectin (p<0.001) and leptin (p<0.001). Adjusted analysis showed that greater SF concentrations of TNF-α, MMP-13 and IL-6 were independent predictors of less pain improvement at two years follow-up (p<0.05).
  
  
  CONCLUSIONS
  Those patients, having ongoing pain despite no clinical or radiological cause, may have an inflammatory profile characterizing a predisposition to ongoing pain after TKA.
  
  
  METHODS
  Prognosis study, Level 2.
authors.affiliation: Division of Orthopaedic Surgery, University Health Network, University of Toronto, Toronto ON, Canada. Rajiv.gandhi@uhn.on.ca
authors.forename: Rajiv
authors.initials: R
authors.lastname: Gandhi
authors.forename: David
authors.initials: D
authors.lastname: Santone
authors.forename: Mark
authors.initials: M
authors.lastname: Takahashi
authors.forename: Omar
authors.initials: O
authors.lastname: Dessouki
authors.forename: Nizar N
authors.initials: NN
authors.lastname: Mahomed
mesh_terms: D052242:Adiponectin / Q000032:analysis / Q000378:metabolism; D000368:Aged; D019645:Arthroplasty, Replacement, Knee / Q000009:adverse effects* / Q000379:methods; D015331:Cohort Studies; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D018836:Inflammation Mediators / Q000032:analysis / Q000378:metabolism*; D015850:Interleukin-6 / Q000032:analysis / Q000378:metabolism; D020738:Leptin / Q000032:analysis / Q000378:metabolism; D016014:Linear Models; D008297:Male; D020781:Matrix Metalloproteinase 1 / Q000032:analysis / Q000378:metabolism; D008875:Middle Aged; D020370:Osteoarthritis, Knee / Q000175:diagnosis / Q000601:surgery; D010147:Pain Measurement; D010148:Intractable Pain / Q000097:blood / Q000175:diagnosis; D010149:Postoperative Pain / Q000175:diagnosis* / Q000453:epidemiology; D011237:Predictive Value of Tests; D018570:Risk Assessment; D012720:Severity of Illness Index; D013582:Synovial Fluid / Q000737:chemistry* / Q000378:metabolism; D013997:Time Factors
chemical_list: D052242:Adiponectin; D018836:Inflammation Mediators; D015850:Interleukin-6; D020738:Leptin; D020781:Matrix Metalloproteinase 1