Osteoarthritis (OA) represents a degenerative joint disease which advances through cartilage breakdown, synovial inflammation, and subchondral bone transformation until it causes persistent pain and mobility loss. The scientific community lacks complete knowledge about OA disease mechanisms and post-operative healing processes despite arthroplasty surgery providing effective symptom relief. This study investigated plasma proteomic changes in OA patients before and after arthroplasty. The cohort included eight OA patients undergoing knee or hip arthroplasty and ten age-, sex-, and body mass index-matched healthy controls. Plasma proteins were analyzed using liquid chromatography–tandem mass spectrometry following enzymatic digestion and depletion of high-abundance components. The bioinformatic analysis together with quantitative methods showed that OA patients experienced changes in inflammatory pathways, extracellular matrix remodeling, immune system regulation and coagulation processes. A total of 93 proteins were differentially abundant in the pre-operative comparison. Among these, 63 proteins were consistently up-regulated and 23 were consistently down-regulated across both pre- and post-operative time points. In addition, 20 proteins exhibited post-operative-specific changes. These findings highlight both persistent disease-associated alterations and transient proteomic shifts linked to post-operative recovery. Overall, this study identifies candidate plasma proteomic signatures associated with OA and surgical intervention, providing exploratory insights into disease monitoring and potential personalized therapeutic strategies.