A Mediation Appraisal of Neuropathic-like Symptoms, Pain Catastrophizing, and Central Sensitization-Related Signs in Adults with Knee Osteoarthritis—A Cross-Sectional Study

Objective. To investigate the relationships among neuropathic pain (NP), pain catastrophizing (PC), and central sensitization (CS) in relation to functional status and radiological damage in patients with knee osteoarthritis (OA). Methods. This cross-sectional study included knee OA patients derived from an observational cohort. The Spearman correlation test was used to analyze the relationship between the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) and the PainDetect Questionnaire (PDQ), Central Sensitization Inventory (CSI), and Pain Catastrophizing Scale (PCS). The Kruskal–Wallis test was employed to compare WOMAC scores according to CSI categories. A multivariate analysis was conducted to identify predictors of functional ability, with the WOMAC score as the dependent variable and the independent variables including painrelated indices such as PCS, PDQ, and CSI, along with Kellgren–Lawrence (K-L) grading and demographic characteristics. Results. This study included 149 patients (76.5% female; mean age 71.5 years; mean duration of pain 8.1 years). In total, 23.5% exhibited NP, 30.9% showed PC, and 33.6% had CS. Higher mean values of WOMAC were correlated with CSI categories (p < 0.0001). WOMAC showed a significant relationship with CSI (rho = 0.791; p < 0.0001), PDQ (rho = 0.766; p < 0.0001), and PCS (rho = 0.536; p < 0.0001). In the multiple regression analysis, WOMAC was independently associated with CSI (p < 0.0001), PDQ (p < 0.0001), and PC (p = 0.0001). No association was observed between the K-L grading and the other variables. Conclusions. A reduced functional capacity in patients with knee OA is correlated with the presence of NP, PC and CS, without being significantly associated with radiological damage.