Characterization of the relationship between radiographic grading and biomarkers in patients with knee osteoarthritis

"Osteoarthritis (OA) is a whole-joint degenerative disease, affecting more than 25% of the adult population. Currently, OA is most commonly diagnosed based on radiographic documentation. However, radiographic grading is only able to diagnose OA at later stages of the disease. Thus, in recent years research into serum, urine and synovial fluid biomarkers has increased in hopes of developing diagnostic, disease stage and prognostic models for OA and increase our understanding of disease biology. The objective of this study was to develop biomarker panels using serum, urine and synovial fluid to predict radiographic grade based on the Kellgren Lawrence (K-L), JS-I-O and Composite scoring systems, and to determine biomarker differences in patients with varying degrees of radiographic marker severity based on the Composite scoring system. Methods: Bilateral anterior posterior and merchant radiographs were obtained from patients undergoing total knee arthroplasty. Serum, urine and synovial fluid were collected from patients prior to or during surgery. Fluid samples were analyzed for biomarkers relating to degradation, synthesis, inflammation and bone metabolism. Results: Biomarker panels were created for each of the radiographic scoring systems. The biomarker panel for composite scoring had the highest overall predictive ability and the K-L grading system had the lowest. Further, each biomarker panel was unique and highlighted different OA disease mechanisms. When examining differences in biomarkers based on radiographic marker severity assessed by the Composite scoring system, biomarker levels were different in patients with: medial and lateral joint space narrowing, osteophyte formation, medial cyst formation, lateral chondrocalcinosis, patellofemoral joint space loss and misalignment. Discussion: These results suggests how you radiographically assess a patient can place them into different cohorts and significantly affect the biomarkers required for development of predictive panels. Further, these results show that differences in biomarker concentrations exist between patients with varying degrees of radiographic markers in specific compartments of the knee. Taken together, this study shows that radiographic grading with the addition of biomarkers can improve our understanding of disease biology, ultimately leading to earlier diagnosis, improved prediction of disease progression, better clinical decision making and better treatment monitoring."--IntroductionIncludes bibliographical references