Proteomics Analysis Reveals Serum Biomarkers Reflecting Joint Pain and Physical Limitations in Knee Osteoarthritis Before and After Joint Replacement Surgery

ObjectiveOsteoarthritis (OA) is an age-related musculoskeletal disorder lacking effective disease-modifying therapies and early diagnostic biomarkers. This study aimed to identify serum proteins that could indicate the occurrence of knee OA (KOA) and correlate with patients' pain and functional impairment.Design/MethodsFasting serum samples were collected from controls (n = 8) and patients with end-stage KOA at baseline (n = 8) and 12 months after total knee arthroplasty (n = 8). Proteomics analysis was conducted with liquid chromatography-mass spectrometry, followed by univariate and multivariate statistics and pathway analyses by MetaboAnalyst and STRING. Partial correlations were calculated with R, adjusted for sex, age, and body mass index, using a linear regression model.Results151 proteins were upregulated and 5 proteins downregulated in baseline KOA compared to control. These proteins were linked to the complement system, immune response, coagulation, inflammatory response, calcium homeostasis, and extracellular matrix remodeling. Of these, complement factor I showed strong biomarker potential. Several proteins emerged as statistically significant predictors of cartilage loss, pain sensitivity, physical function, and corticospinal excitability. Systemic alterations persisted 12 months after surgery.ConclusionSerum proteins may serve as biomarkers of KOA, reflecting disease-related immune, inflammatory, and tissue-remodeling processes that persist after joint replacement.