Presentation: Baseline Effusion but Not Synovitis Predicts Cartilage Loss Over 30 Months in Subjects without Tibiofemoral Osteoarthritis - Results From the Multicenter Osteoarthritis (MOST) Study (ACR/ARHP Annual Scientific Meeting)

Sunday, October 18, 2009: 9:00 AM - 11:00 AM

Hall D (Pennsylvania Convention Center)

Frank W. Roemer¹, Ali Guermazi¹, David T. Felson¹, Jingbo Niu¹, Michael C. Nevitt², Michel D. Crema³, John A. Lynch⁴, C. Lewis⁵, James Torner⁶ and Yuqing Zhang¹, ¹Boston University School of Medicine, Boston, MA, ²University of California, San Francisco, San Francisco, CA, ³BUSM, Boston, MA, ⁴UCSF, San Francisco, CA, ⁵UAB, Birmingham, AL, ⁶UIowa, Iowa City, IA

Presentation Number: 199

Poster Board Number: 199

Purpose: Synovitis and effusion are frequently present in knee osteoarthritis (OA) and correlate with pain and other clinical outcomes. If synovitis or effusion in OA appears to predispose to further structural progression has been questioned. Synovitis present in OA is thought to be triggered by cartilage detritus, and thus seems to be a secondary phenomenon. However, the clinical data supporting this theory is limited. Synovial inflammation is regularly observed in early OA, but as to whether it occurs prior to damage of other tissues remains unclear. Aim of the study was to assess if presence of baseline synovitis and effusion in knees without OA, predicts future cartilage loss.
Method: The Multicenter Osteoarthritis (MOST) Study is a longitudinal observational study of subjects with OA or at risk of developing OA. The MRI protocol included axial and sagittal proton-density weighted fat-suppressed fast spin echo and coronal STIR sequences. MRI was performed at a 1.0 T extremity system. MRIs were assessed semiquantitatively according to the WORMS scoring system. Only knees without radiographic OA and no baseline tibio-femoral cartilage damage were included. A synovitis-surrogate of signal changes in the infrapatellar and intercondylar areas of Hoffa’s fat pad, and effusion were both scored from 0-3. Presence of definite synovitis and effusion was defined as any grade ≥ 2. Knees with scores of either 0 or 1 were the reference. Logistic regression was used to estimate the risk of cartilage loss at follow-up. Cartilage loss was defined as an increase of at least 0.5 grade (subtle within-grade progression, that did not fulfill the criteria of a full-grade change) in any subregion. Adjustment was performed for possible confounders of future tibio-femoral cartilage damage, i.e. baseline effusion for synovitis model, synovitis for effusion model, patellofemoral cartilage damage, meniscus damage, meniscal extrusion, body mass index, age, gender, malalignment, bone marrow lesions.

Results: 514 knees were included (55.6% women, mean age 60.1 ± 7.2, mean BMI 29.1 ± 4.5). 43 (8.4%) knees showed synovitis, and 53 (10.3%) presented with joint effusion at baseline. 137 (26.7%) knees showed cartilage loss at follow-up. After adjustment, baseline synovitis was not associated with an increased risk of cartilage loss at follow-up (adjusted odds ratio 1.0 [95% confidence intervals 0.5-2.1, p=0.89]). Knees with baseline effusion had an increased risk for cartilage loss (adjusted odds ratio 2.7 [95% confidence intervals 1.4-5.1, p=0.002]).

Conclusion: Baseline synovitis does not predict cartilage loss, but joint effusion. However, contrast-enhanced MRI, which is able to directly depict the inflamed synovium, might yield different results. Baseline effusion as a reflection of synovial activation seems to play a role in predicting structural progression in early or pre-OA.

Keywords: Knee, cartilage and synovitis

Disclosure: F. W. Roemer, Boston Imgaing Core Lab, LLC, 4 ; A. Guermazi, Synarc, Inc., 1, Boston Imaging Core Lab, LLC, 4, MerckSerono; Facet Solutions , 5, GE HealthCare, 2 ; D. T. Felson, None; J. Niu, None; M. C. Nevitt, None; M. D. Crema, Boston Imaging Core Lab, LLC, 4 ; J. A. Lynch, None; C. Lewis, None; J. Torner, None; Y. Zhang, None.

199 - Baseline Effusion but Not Synovitis Predicts Cartilage Loss Over 30 Months in Subjects without Tibiofemoral Osteoarthritis - Results From the Multicenter Osteoarthritis (MOST) Study