Inflammatory predictors of ongoing pain 2 years following knee replacement surgery

Introduction: 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-1 beta (p<0.002), MIP-1 beta (p<0.001), adiponectin (p<0.001) and leptin (p<0.001). Adjusted analysis showed that greater SF concentrations of TNF-alpha, 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. Level of Evidence: Prognosis study, Level 2. (C) 2012 Elsevier B.V. All rights reserved.