Background Studies have shown associations of structural progression of knee OA with several MRI-assessed pathologic features such as bone marrow lesions (BMLs) cartilage damage and meniscal lesions1,2. However previous studies commonly evaluated one risk factor at a time and not in a combination simultaneously, though these features are known to partly coexist.
Objectives To determine which radiographic and semiquantitative MRI-based OA features predict cartilage thickness loss in the same femorotibial compartment (FTC).
Methods One knee of each subject of a subcohort of Multicenter OA Study (MOST) was evaluated. The subcohort comprised persons who volunteered for a longitudinal study, in which quantitative MRI-based cartilage thickness was done. These subjects also had MRI for semiquantitative Whole Organ MRI Score based evaluation of BMLs, cartilage damage, meniscal damage and extrusion, Hoffa-synovitis and effusion-synovitis, at baseline and at 30-month. Progression in medial or lateral FTC (MFTC/LFTC) was defined as cartilage thinning exceeding the change observed in OAI control cohort knees (mean ± 2xSD, MFTC/LFTC: -162μm/-145μm). All MRI predictors were dichotomized into present/absent. Differences in baseline scores of predictor variables in the same FTC were compared between progressor and nonprogressor knees using multivariable logistic regression adjusting for age, sex, BMI and alignment axis. We combined MFTC and LFTC to calculate adjusted odds ratio (aOR) and 95% CI of cartilage thickness loss across compartments (ie. medial cartilage thinning with medial risk factors and lateral cartilage thinning with lateral risk factors) using GEE. ORs and 95%CIs were also calculated for MFTC and LFTC cartilage thickness loss, individually.
Results 196 persons with mean age 59.8±6.3 years, mean BMI 29.5±4.6 and 62% women were included. 46 knees had baseline radiographic knee OA (KL grade≥2). In the MFTC/LFTC, 35/29 progressors and 161/167 nonprogressors were observed, respectively. Change in MFTC cartilage thickness was -63.0μm and that in LFTC cartilage thickness -25.1μm. For combined MFTC+LFTC analysis, predictors of cartilage thinning were baseline BML (aOR 1.9 95%CI [1.1-3.3]), cartilage damage (2.6 [1.4-5.0]), meniscal damages (4.5 [2.4-8.4]) and meniscal extrusion (3.3 [1.9-5.8]), all in the same FTC. Hoffa- and effusion-synovitis did not predict cartilage thinning. In MFTC-only analysis MFTC progressors showed higher aOR for having baseline meniscal damage (2.4 [1.1-5.6]) and meniscal extrusion (2.6 [1.1-5.8]). In LFTC-only analysis baseline cartilage damage (3.4 [1.3-9.3]), meniscal damage (13.9 [3.3-9.0]) and meniscal extrusion (5.0 [1.4-18.0]) predicted LFTC progression.
Conclusions The presence of semiquantitatively assessed BMLs, cartilage damage, meniscal damage and extrusion in the same FTC predict cartilage thickness loss over 30-months.
Roemer et al. Arthritis Rheum 2012;64:1888-98.
Crema et al. Osteoarthritis Cartilage 2010;18:336-43.
Disclosure of Interest : A. Guermazi Shareholder of: Boston Imaging Core Lab, LLC, Consultant for: Merck Serono, TissueGene, Sanofi Aventis, F. Eckstein Shareholder of: Chondrometrics GmbH, Consultant for: MerckSerono and Abbvie, D. Hayashi: None declared, F. Roemer Shareholder of: Boston Imaging Core Lab, LLC, Consultant for: Merck Serono and the NIH, W. Wirth Shareholder of: Chondrometrics, GmbH, T. Yang: None declared, J. Niu: None declared, L. Sharma: None declared, M. Nevitt: None declared, C. Lewis: None declared, J. Torner: None declared, D. Felson: None declared