OP0144 Infra Patellar Fat Pad Signal Intensity Alterations and Effusion-Synovitis Predict Knee Pain, Cartilage Volume Loss and Total Knee Replacement over 10.7 Years in Older Adults
Authors: B.S. Eathakkattu Antony, X. Jin, X. Wang, W. Han, F. Cicuttini, C. Ding, G. Jones
Journal: Annals of the Rheumatic Diseases (2016)

<h3>Background</h3> There are no long-term studies that describe the independent association of infrapatellar fat pad (IPFP) signal intensity alterations and effusion-synovitis with knee osteoarthritis (KOA) severity and progression. <h3>Objectives</h3> To describe the associations between baseline IPFP signal intensity alterations and effusion-synovitis and long-term knee pain, knee dysfunction, tibial cartilage volume loss and total knee replacement (TKR) over 10.7 years. <h3>Methods</h3> Participants (n=983, mean age 62.8 years, 50% female) were selected randomly from the local community of Tasmania and followed up at 2.6 years, 5.1 years and 10.7 years later. MRI was acquired at baseline and 10.7 year follow-up. Effusion-synovitis was measured on T2-weigthed MRI using a modified WORMS system (grade 0–3) at suprapatellar pouch, central portion, posterior femoral recess and subpopliteal recess. IPFP signal intensity alteration was assessed on T2-weighted MRI and was defined as discrete areas of increased signal within IPFP, and was graded as follows: grade 0 = none; grade 1 = &lt;10% of the region; grade 2 = 10% to 20% of the region; grade 3 = &gt;20% of the region. Cartilage volume at baseline and 10.7 years was measured using manual segmentation of T1-weighted MRI. Clinical symptoms and TKR data were recorded at each follow-up visit. Multivariable analyses were performed using linear mixed-effects models for clinical symptoms, linear regression for cartilage volume loss and cox proportional hazards for TKR. <h3>Results</h3> After adjustment for age, sex, BMI, radiographic KOA status, baseline IPFP signal intensity alteration was associated with total WOMAC score (β=2.19, 95% CI = 0.29, 4.09), WOMAC pain and WOMAC function scores (all p&lt;0.01) over 10.7 years. However, these associations became borderline significance after further adjustment for cartilage defects, BMLs or effusion-synovitis. Baseline IPFP signal intensity alteration was independently associated with tibial cartilage volume loss (β=0.08 mm<sup>3</sup>, 95% CI = 0.14, 0.02) and TKR (HR=1.89, 95% CI = 1.31, 2.74) over 10.7 years. Baseline total effusion-synovitis and suprapatellar pouch effusion-synovitis were independently associated with total WOMAC score (β=2.08,95%CI=0.16,4.16) and pain and dysfunction scores (all p&lt;0.05) over 10.7 years. However, there was no significant association between effusion-synovitis and cartilage volume loss. Total (HR=1.58,95%CI=1.01,2.49), sub popliteal recess (HR=1.53, 95%CI=1.11,2. 11) and suprapatellar pouch (HR=1.90,95%CI=1.25,2.89) effusion-synovitis was associated with TKR over 10.7 years. However, these associations were dependent of other structural pathologies except grade 3 suprapatellar effusion-synovitis. <h3>Conclusions</h3> Signal intensity alterations of IPFP at baseline were significantly associated tibial cartilage volume loss and TKR over 10.7 years independent of other structural pathologies. Effusion-synovitis (especially at suprapatellar pouch) was independently associated with knee pain and TKR. These results suggest that effusion-synovitis was associated with clinical progression and IPFP signal intensity alteration was associated with structural progression and TKR, and can be used as independent markers of progression of KOA. <h3>Acknowledgement</h3> National Health and Medical Research Council of Australia funded this study. <h3>Disclosure of Interest</h3> None declared