SAT0534 MAGNETIC RESONANCE IMAGING MARKERS IMPROVE THE PREDICTION MODEL FOR TOTAL KNEE REPLACEMENT OVER 13 YEARS IN OLDER ADULTS
Authors: Benny Antony, Ishanka Munugoda, Dawn Aitken, Petr Otahal, Michelle Lorimer, Stephen Graves, Johanne Martel-Pelletier, Jean-Pierre Pelletier, Flavia Cicuttini, Graeme Jones
Journal: Annals of the Rheumatic Diseases (2019)

<h3>Background:</h3> Quantitative and semi-quantitative measurement of structural changes on MRI have been widely adopted in knee osteoarthritis (OA) research. However, few long-term studies describe the independent association of these structural factors and total knee replacement (TKR) in older adults. <h3>Objectives:</h3> To describe whether cartilage defects, bone marrow lesions (BMLs), effusion-synovitis, and meniscal pathologies at baseline are associated with TKR over 13 years and to estimate the additive effect of these measures for risk prediction of TKR. <h3>Methods:</h3> 1082 participants (mean age 62.8 years, 50% female) were randomly recruited from Tasmania and followed over 13.3 years. A 1.5T MRI scan of the right knee was acquired at baseline (n=930). Cartilage defects (grade 0-4), BMLs (grade 0-3), effusion-synovitis (grade 0-3), meniscal tears (grade 0-3) and meniscal extrusion (grade 0-2) was scored at baseline using T1-weighted and T2-weighted MRI. WOMAC knee pain was recorded from questionnaires and radiographic OA (ROA) was assessed by OARSI scale. The incidence of primary (first-time) TKR was determined by data linkage to the Australian Orthopaedic Association National Joint Replacement Registry (AOANJRR). Log binomial regression were used to estimate the risk of TKR associated with baseline MRI measures, adjusting for age, sex, BMI, ROA, and pain. Receiver operating characteristic (ROC) analyses were used and area under the curves (AUCs) were compared. <h3>Results:</h3> After adjustment for age, sex, BMI, and ROA status, baseline cartilage defects (grade 2, RR=6.71; grade 3, RR=11.17; grade 4, RR=13.2; all p&lt;0.01) were consistently and significantly associated with TKR over 13 years. These associations remained significant after further adjustment for other MRI pathologies. BMLs (grade 1, RR=2.74; grade 2, RR=2.64; grade 3 RR=4.01, all p&lt;0.05 except grade 2), grade 3 effusion-synovitis (RR=2.74, p&lt;0.05) and suprapatellar effusion-synovitis area were associated with TKR over 13 years. However, these associations of BMLs and effusion-synovitis with TKR were largely dependent on cartilage defects. Those who had TKR all had a meniscal tear at baseline, with 96% of them having a grade 3 tear. Compared to the baseline model with age, sex and BMI (area under the ROC curve [AUC = 0.62]), Model 1 with the addition of ROA and WOMAC pain performed better (AUC =0.77). Addition of cartilage defects to Model 1 resulted in a significant increase of AUC to 0.84. However, addition of BMLs and effusion-synovitis to the model 1 resulted in a nonsignificant small increase in AUC (0.78 and 0.76) only. The combination of all MRI pathologies to Model 1 resulted in a significant increase of AUC to 0.82. <h3>Conclusion:</h3> Baseline knee MRI structural pathology markers can predict TKR over the long-term, suggesting that MRI structural markers are good predictors of rapid knee OA progression in the general population. Semiquantitative MRI measures such as cartilage defects significantly improve the model performance for prediction of TKR over 13 years, and hence could be utilized in prediction/decision making of TKR. <h3>Disclosure of Interests:</h3> Benny Antony: None declared, Ishanka Munugoda : None declared, Dawn Aitken: None declared, Petr Otahal: None declared, Michelle Lorimer: None declared, Stephen Graves : None declared, Johanne Martel-Pelletier Shareholder of: ArthroLab Inc., Consultant for: TRB Chemedica SA, Jean-Pierre Pelletier Shareholder of: Shareholder in ArthroLab Inc., Grant/research support from: Study funded by TRB Chemedica SA, Consultant for: TRB Chemedica SA, Flavia Cicuttini: None declared, Graeme Jones: None declared