M.D. Crema

MRI features of cystic lesions around the knee.

Cystic lesions around the knee are a diverse group of entities, frequently encountered during routine MRI of the knee. These lesions range from benign cysts to complications of underlying diseases such as infection, arthritis, and malignancy. MRI is the technique of choice in characterizing lesions around the knee: to confirm the cystic nature of the lesion, to evaluate the anatomical relationship to the joint and surrounding tissues, and to identify associated intra-articular disorders. We will discuss the etiology, clinical presentation, MRI findings, and differential diagnosis of various cystic lesions around the knee including meniscal and popliteal (Bakers) cysts, intra-articular and extra-articular ganglia, intra-osseous cysts at the insertion of the cruciate ligaments and meniscotibial attachments, proximal tibiofibular joint cysts, degenerative cystic lesions (subchondral cyst), cystic lesions arising from the bursae (pes anserine, prepatellar, superficial and deep infrapatellar, iliotibial, tibial collateral ligament, and suprapatellar), and lesions that may mimic cysts around the knee including normal anatomical recesses. Clinicians must be aware about the MRI features and the differential diagnosis of cystic lesions around the knee to avoid misdiagnosis.

The association of prevalent medial meniscal pathology with cartilage loss in the medial tibiofemoral compartment over a 2-year period.

OBJECTIVE To investigate the association of different types of magnetic resonance imaging (MRI)-detected medial meniscal pathology with subregional cartilage loss in the medial tibiofemoral compartment. METHODS A total of 152 women aged >or=40 years, with and without knee osteoarthritis (OA) were included in a longitudinal 24-month observational study. Spoiled gradient recalled acquisitions at steady state (SPGR) and T2-weighted fat-suppressed MRI sequences were acquired. Medial meniscal status of the anterior horn (AH), body, and posterior horn (PH) was graded at baseline: 0 (normal), 1 (intrasubstance meniscal signal changes), 2 (single tears), and 3 (complex tears/maceration). Cartilage segmentation was performed at baseline and 24-month follow-up in various tibiofemoral subregions using computation software. Multiple linear regression models were applied for the analysis with cartilage loss as the outcome. In a first model, the results were adjusted for age and body mass index (BMI). In a second model, the results were adjusted for age, BMI and medial meniscal extrusion. RESULTS After adjusting for age, BMI, and medial meniscal extrusion, cartilage loss in the total medial tibia (MT) (0.04 mm, P=0.04) and the external medial tibia (eMT) (0.068 mm, P=0.04) increased significantly for compartments with grade 3 lesions. Cartilage loss in the total central medial femoral condyle (cMF) (0.071 mm, P=0.03) also increased significantly for compartments with grade 2 lesions. Cartilage loss at the eMT was significantly related to tears of the PH (0.074 mm; P=0.03). Cartilage loss was not significantly increased for compartments with grade 1 lesions. CONCLUSION The protective function of the meniscus appears to be preserved in the presence of intrasubstance meniscal signal changes. Prevalent single tears and meniscal maceration were found to be associated with increased cartilage loss in the same compartment, especially at the PH.

Semiquantitative assessment of focal cartilage damage at 3 T MRI: A comparative study of dual echo at steady state (DESS) and intermediate-weighted (IW) fat suppressed fast spin echo sequences

PURPOSE The aim of the study was to compare semiquantitative assessment of focal cartilage damage using the dual echo at steady state (DESS)- and intermediate-weighted (IW) fat suppressed (fs) sequences at 3T MRI. METHODS Included were 201 subjects aged 35-65 with frequent knee pain. MRI was performed with the same sequence protocol as in the Osteoarthritis Initiative (OAI): sagittal IW fs, triplanar DESS and coronal IW sequences. Cartilage status was scored according to the WORMS system using all five sequences. A total of 243 focal defects were detected. In an additional consensus reading, the lesions were evaluated side-by-side using only the sagittal DESS and IW fs sequences. Lesion conspicuity was graded from 0 to 3, intrachondral signal changes adjacent to the defect were recorded and the sequence that depicted the lesion with larger diameter was noted. Wilcoxon signed-rank tests, controlled for clustering by person, were used to examine differences between the sequences. RESULTS 37 (17.5%) of the scorable lesions were located in the medial tibio-femoral (TF), 48 (22.7%) in the lateral TF and 126 (59.7%) in the patello-femoral compartment. 82.5% were superficial and 17.5% full-thickness defects. Conspicuity was superior for the IW sequence (p<0.001). The DESS sequence showed more associated intrachondral signal changes (p<0.001). In 103 (48.8%) cases, the IW fs sequence depicted the lesions as being larger (p<0.001). CONCLUSIONS The IW fs sequence detected more and larger focal cartilage defects than the DESS. More intrachondral signal changes were observed with the DESS.

Risk factors for magnetic resonance imaging-detected patellofemoral and tibiofemoral cartilage loss during a six-month period: the joints on glucosamine study.

OBJECTIVE To assess several baseline risk factors that may predict patellofemoral and tibiofemoral cartilage loss during a 6-month period. METHODS For 177 subjects with chronic knee pain, 3T magnetic resonance imaging (MRI) of both knees was performed at baseline and followup. Knees were semiquantitatively assessed, evaluating cartilage morphology, subchondral bone marrow lesions, meniscal morphology/extrusion, synovitis, and effusion. Age, sex, and body mass index (BMI), bone marrow lesions, meniscal damage/extrusion, synovitis, effusion, and prevalent cartilage damage in the same subregion were evaluated as possible risk factors for cartilage loss. Logistic regression models were applied to predict cartilage loss. Models were adjusted for age, sex, treatment, and BMI. RESULTS Seventy-nine subregions (1.6%) showed incident or worsening cartilage damage at followup. None of the demographic risk factors was predictive of future cartilage loss. Predictors of patellofemoral cartilage loss were effusion, with an adjusted odds ratio (OR) of 3.5 (95% confidence interval [95% CI] 1.3-9.4), and prevalent cartilage damage in the same subregion with an adjusted OR of 4.3 (95% CI 1.3-14.1). Risk factors for tibiofemoral cartilage loss were baseline meniscal extrusion (adjusted OR 3.6 [95% CI 1.3-10.1]), prevalent bone marrow lesions (adjusted OR 4.7 [95% CI 1.1-19.5]), and prevalent cartilage damage (adjusted OR 15.3 [95% CI 4.9-47.4]). CONCLUSION Cartilage loss over 6 months is rare, but may be detected semiquantitatively by 3T MRI and is most commonly observed in knees with Kellgren/Lawrence grade 3. Predictors of patellofemoral cartilage loss were effusion and prevalent cartilage damage in the same subregion. Predictors of tibiofemoral cartilage loss were prevalent cartilage damage, bone marrow lesions, and meniscal extrusion.

The association between meniscal and cruciate ligament damage and knee pain in community residents

OBJECTIVE To describe the frequency of meniscal and cruciate ligament damage by magnetic resonance imaging (MRI) and to examine its association with knee pain in community residents in Korea. METHODS Participants were randomly chosen regardless of knee osteoarthritis (OA) or pain from the population-based Hallym Aging Study. Demographic and knee pain data were obtained by questionnaire. Radiographic evaluations consisted of weight-bearing knee A-P radiographs and 1.5-T MRI scans. We assessed the integrities of the menisci and cruciate ligaments in the dominant knee of subjects without knee pain or in the more symptomatic knee among subjects with knee pain, and examined their association with knee pain using a logistic regression model. RESULTS The mean age of the 358 study subjects was 71.8 years, and 51.4% were women. Meniscal and cruciate ligament damage were present in 49.7% and 8.0% of men and in 71.2% and 26.9% of women, respectively. The presence of meniscal damage was significantly associated with the presence of knee pain among subjects without radiographic knee OA (ROA), but not among subjects with ROA. The presence of cruciate ligament tear was associated with knee pain in subjects with or without ROA. The severity of knee pain was significantly correlated with medial meniscal damage grade but not with cruciate ligament tear. CONCLUSION Incidental meniscal or cruciate findings on MRI were common in this elderly population. Among subjects without ROA, the presence of meniscal or cruciate damage was significantly associated with knee pain. The medial meniscal grade was significantly correlated with knee pain severity.

Association between bone marrow lesions detected by magnetic resonance imaging and knee pain in community residents in Korea

OBJECTIVE To describe the frequency of bone marrow lesions (BMLs) detected by magnetic resonance imaging (MRI), and to examine the association of BMLs with knee pain severity in community residents in Korea. METHODS Participants were randomly chosen from the population-based Hallym Aging Study, irrespective of whether they had knee osteoarthritis (OA) or pain. Demographic and knee pain data were obtained by questionnaire. Radiographic evaluations consisted of weight-bearing knee anteroposterior radiographs and 1.5-T MRI scans. MRI was performed in the dominant knees of subjects without knee pain and in the more symptomatic knees of subjects with knee pain. BMLs were graded according to the whole-organ MRI score. RESULTS The mean age of the 358 study subjects was 71.8 years, and 34.5% of subjects had radiographically detected knee OA. The prevalences of BMLs and large BMLs in the tibiofemoral compartments were 80.3% and 40.4%, respectively. After adjusting for age, sex, and body mass index, total and medial compartment BML scores were significantly associated with the presence of knee pain, and the association was stronger as the summary score for BML increased. In proportional regression analysis, knee pain severity increased with BML severity in any compartment and in the medial compartment. CONCLUSION BMLs detected by MRI were highly prevalent in this elderly Asian population. BMLs were significantly linked to knee pain, and BML severity correlated with knee pain severity. BMLs may be important surrogate targets for monitoring pain and structure modification in OA therapeutics.

387 PERIPATELLAR SYNOVITIS IN OSTEOARTHRITIS: COMPARISON OF NON-ENHANCED AND ENHANCED MAGNETIC RESONANCE IMAGING (MRI) AND ITS ASSOCIATION WITH PERIPATELLAR KNEE PAIN. THE MOST STUDY

Results: The cartilage tissue in the human TMJ was clearly visible and distinguishable from bone after contrast enhancement with Optiray (Fig. 1a, 1b). Furthermore, three-dimensional bone reconstructions enabled quantitative analysis and detection of bone abnormalities (Fig. 1c). Easy discrimination between cartilage and SCB allowed for separate visualization in 3D reconstruction and for measures on cartilage thickness (Fig. 1b, 1d). The average cartilage thickness was 0.33±0.04mm (range: 0.28−0.36mm) and 0.32±0.22mm (range: 0.072−0.695mm) for the healthy and OA-classified samples, respectively. Conclusions: The present study provides new information about the application of Optiray as a tool to visualize both bone and cartilage tissue in TMJ reconstructions obtained with a mCT system. This combined method makes quantitative measures of both articular cartilage and the underlying bone possible at high resolution. To our knowledge, this is the first time simultaneous assessment of bone and cartilage components has been performed in the human TMJ. With the presented methodology a direct relationship between OA-like features in bone and cartilage can be established. Furthermore, this method can be used for the development of large scale finite element models for the examination of the biomechanical interaction between articular cartilage and SCB in both a healthy and OA situation.

400 DO BASELINE SYNOVITIS AND EFFUSION PREDICT TIBIOFEMORAL CARTILAGE LOSS OVER 30 MONTHS IN SUBJECTS WITHOUT RADIOGRAPHIC OSTEOARTHRITIS? RESULTS FROM THE MULTICENTER OSTEOARTHRITIS (MOST) STUDY

400 – Table 1. Longitudinal association between baseline synovitis and effusion and cartilage status at 30-months follow-up Synovitis and effusion at baseline (514 knees) Cartilage status at follow-up Crude OR (95% CI) Adjusted OR* (95% CI) No cartilage loss (n=377) Cartilage loss (n=317) Synovitis absence (grades 0 and 1) (N=467) 348 (74.5%) 119 (25.5%) 1.0 (reference) 1.0 (reference) Synovitis presence (maximum grade ≥2) (N=47) 29 (61.7%) 18 (38.3%) 1.4 (0.7–2.7) 1.0 (0.5–2.1) p=0.89 Effusion absence ((grades 0 and 1) (N=461) 352 (76.4%) 109 (23.6%) 1.0 (reference) 1.0 (reference) Effusion presence (grade ≥2) (N=53) 25 (47.2%) 28 (52.8%) 3.4 (1.9–6.2) 2.7 (1.4–5.1) p=0.002 *Results adjusted for baseline effusion, synovitis, patellofemoral cartilage damage, meniscus damage, meniscus extrusion, body mass index, age, gender, malalignment, bone marrow lesions. 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 a 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 tibiofemoral cartilage damage, i.e. baseline effusion in the synovitis model, baseline synovitis in effusion model, patellofemoral cartilage damage, meniscus damage, meniscal extrusion, body mass index (BMI), age, gender, malalignment, bone marrow lesions. Results: 514 knees (1 knee per patient) were included (55.6% women, mean age 60.1±7.2, mean BMI 29.1±4.5). 47 (9.1%) knees showed synovitis, and 53 (10.3%) presented with joint effusion at baseline, 137 (26.7%) knees exhibited cartilage loss during follow-up. After adjustment, baseline synovitis was not associated with an increased risk of cartilage loss at followup (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]). Conclusions: Baseline synovitis in knees without radiographic OA, as assessed on non-enhanced MRI, does not predict cartilage loss, but joint effusion. However, assessment of baseline synovitis on contrast-enhanced MRI might yield different results. Baseline effusion, which reflects synovial activation, predicts structural progression in subjects without radiographic OA.

374 TIBIOFEMORAL BONE MARROW LESIONS AND THEIR ASSOCIATION WITH PREVALENT AND INCIDENT SUBCHONDRAL BONE ATTRITION: THE MOST STUDY

Purpose: Although subchondral cysts (SCs) represent a common finding in osteoarthritic knees, their etiology is still controversial. The synovial fluid intrusion theory suggests that elevated intraarticular pressure leads to intrusion of synovial fluid into the bone through gaps in the articular surface with subsequent bone resorption. The bony contusion theory suggests that SCs are foci of bone necrosis produced by impact between opposing articular surfaces. The detection of small lesions is crucial to understand the pathogenesis of SCs, as large lesions are usually found in end-stage disease. MRI is more sensitive to detect small SCs than x-ray, demonstrating well-defined rounded areas of fluid-like signal intensity on non enhanced imaging. We assessed the association of SCs with subchondral bone marrow edema-like lesions (BMLs), as well as the cartilage status in the same subregions where SCs were observed in order to evaluate the bony contusion vs. the synovial fluid intrusion theory of SC formation. Methods: The Multicenter Osteoarthritis (MOST) Study is a NIH-funded longitudinal observational study of individuals who have or are at high risk for knee OA. MRI scans were performed on a 1.0T extremity system (ONI Medical Systems, OrthOneTM) using axial and sagittal proton density weighted fat suppressed sequences and a coronal STIR sequence. The sample used for the analysis was a cross-sectional subset of the MRI examinations from the 30-month follow-up visit. MRIs were read using the WORMS system by two musculoskeletal radiologists (MDC, MDM). The tibiofemoral joint was subdivided into 10 subregions and the patellofemoral joint was subdivided into 4 subregions. SCs and BMLs were scored semiquantitatively from 0 to 3 in each of the 14 subregions. In subregions where SCs were present, the cartilage status was categorized as 0=normal, 1 = partial-thickness loss, and 2= full thickness loss. We evaluated the cross-sectional association of prevalent BMLs (score >0) with the presence of prevalent SCs (score >0) on a per-subregion basis using logistic regression with generalized estimating equations to account for correlations among the subregions within a knee (using one knee per person). We then evaluated the distribution of SCs in subregions with normal adjacent cartilage, partial-thickness loss, and full-thickness loss of adjacent cartilage. Results: 400 knees (5600 subregions) were included in the analysis (women: 46.2%, mean age 58.8±7.1, mean BMI 29.5±4.9). SCs were detected in 260 subregions (4.6%) and BMLs were detected in 757 subregions (13.5%). 84.6% of detected SCs were grade 1 lesions. The presence of any BMLs was associated with an odds ratio of 83.5 (95% confidence intervals 42.5–164; p< 0.0001) for presence of SCs in the same subregion. A larger size of BMLs was associated with an increased prevalence of SCs (Table 1). SCs were detected in 121 subregions (46.5%) without full-thickness cartilage loss. Conclusions: Subchondral BMLs are strongly associated with SCs in the same subregion, supporting the bony contusion theory of SCs formation. A substantial amount of SCs were located in subregions without full-thickness cartilage loss, which does not support the synovial fluid intrusion theory of SCs formation.

402 WHOLE-KNEE SYNOVITIS SEMIQUANTITATIVELY ASSESSED ON T1-WEIGHTED CONTRAST-ENHANCED MRI IS ASSOCIATED WITH RADIOGRAPHIC TIBIOFEMORAL OSTEOARTHRITIS AND SEVERE MENISCAL DAMAGE: THE MOST STUDY

401 – Table 1. Association between prevalent BMLs and incident SCs in the same subregion BML status at baseline SCs status at follow-up Adjusted OR (95% confidence interval) p (1283 knees; 16349 subregions) Absence (grade 0) Presence (grade ≥1) (N=16133; 98.7%) (N=216; 1.3%) Absence (grade 0) (N=14506; 88.7%) 14428 (99.5%) 78 (0.5%) 1.0 (reference) Presence (grade ≥1) (N=1843; 11.3%) 1705 (92.5%) 138 (7.5%) 12.9 (8.9, 18.6) p<0.0001 Grade 1 (N=1389; 8.5%) 1304 (93.9%) 85 (6.1%) 10.9 (7.4, 16.1) p<0.0001 Grade 2 (N=341; 2.1%) 302 (88.6%) 39 (11.4%) 19.9 (11.8, 33.6) p<0.0001 Grade 3 (N=113; 0.7%) 99 (87.6%) 14 (12.4%) 21.5 (10.9, 42.1) p<0.0001 Abstract 401 – Table 2. Association between prevalent full-thickness cartilage loss and incident SCs in the same subregion401 – Table 2. Association between prevalent full-thickness cartilage loss and incident SCs in the same subregion Cartilage status at baseline SCs status at follow-up Adjusted OR (95% confidence interval) p (1283 knees; 16349 subregions) Absence (grade 0) Presence (grade ≥1) (N=16133; 98.7%) (N=216; 1.3%) No full-thickness loss (grades 0,1,2,3, and 4) (N=14725; 90.1%) 14588 (99.1%) 137 (0.9%) 1.0 (reference) Full-thickness loss (grades 2.5, 5, and 6) (N=1624; 9.9%) 1545 (95.1%) 79 (4.9%) 1.4 (1.0, 2.0) p=0.036 Grade 2.5 (N=235; 1.4%) 234 (99.6%) 1 (0.4%) 0.3 (0.1, 2.2) p=0.23 Grade 5 (N=940; 5.7%) 893 (95%) 47 (5%) 1.4 (0.9, 2.1) p=0.09 Grade 6 (N=449; 2.8%) 418 (93.1%) 31 (6.9%) 1.3 (0.8, 2.1) p=0.31 402 WHOLE-KNEE SYNOVITIS SEMIQUANTITATIVELY ASSESSED ON T1-WEIGHTED CONTRAST-ENHANCED MRI IS ASSOCIATED WITH RADIOGRAPHIC TIBIOFEMORAL OSTEOARTHRITIS AND SEVERE MENISCAL DAMAGE: THE MOST STUDY A. Guermazi1, F.W. Roemer1,2, Y. Zhu1, M.D. Crema1, M.K. Javaid3, M.D. Marra1, J.A. Lynch4, G. El-Khoury5, Y. Zhang1, M.C. Nevitt4, C.E. Lewis6, D.T. Felson1 1Boston Univ. Sch. of Med., Boston, MA; 2Klinikum Augsburg, Augsburg, Germany; 3Oxford Univ., Oxford, United Kingdom; 4Univ. of California San Francisco, San Francisco, CA; 5Univ. of Iowa, Iowa City, IA; 6Univ. of Alabama, Birmingham, Birmingham, AL Purpose: Synovitis in osteoarthritis (OA) is thought to be a secondary phenomenon related to cartilage and bone alterations and is triggered probably by release of detritus from these structures. Animal models have also shown that synovial cell response plays an important role in meniscal tear repair. An association between meniscal damage and joint effusion as well as synovitis has been reported. Magnetic resonance imaging (MRI) studies investigating synovitis showed that quantification of synovitic alterations is ideally performed on contrast-enhanced (CE) T1-weighted (T1w) MRI. A comprehensive and reliable semiquantitative scoring system to assess whole knee synovitis on CE MRI has been introduced recently. Purpose of our study was to examine the association of whole knee synovitis with radiographic tibiofemoral (TF) OA, with MRIassessed cartilage damage and meniscus status. Methods: The MOST study is a longitudinal observational study of individuals who have or are at high risk for knee OA. Subjects are a subset of MOST who were examined with CE MRI (n=404). Synovitis was scored semiquantitatively from 0 to 3 at 11 sites of the joint. The majority of MRIs (85%) were also assessed according to the WORMS system. Two experienced radiologists performed the readings. Intraand interobserver reliability for synovitis scoring: 0.60-1.00 (w-kappa). To define whole-knee synovitis we summed the scores for the 11 sites and categorized as follows: 0-6 = equivocal synovitis, 7-12 = mild synovitis, 13-18 = moderate synovitis, >18 = severe synovitis. The proportional odds model was used to assess possible cross-sectional associations between radiographic OA (Kellgren Lawrence Grade), cartilage damage (numbers of subregions affected), meniscal status (using maximum scores) and whole knee synovitis. In a second analysis the maximum synovitis score at any site was used as the outcome. Adjustment was performed for age, gender and body mass index. S212 Poster Presentations Figure 1. Example of synovitis in osteoarthritis. Sagittal T1w CE image. Severe synovitis posterior to the posterior cruciate ligament (large arrow) and in Hoffa’s fat pad (arrowheads) is visualized. Note also moderate synovitis in suprapatellar bursa (small arrows). Results: 404 knees (one knee per subject) were included in the analysis (mean age 58.8 years ± 7.0, mean BMI 29.5±4.9, 45.7% women). Defined by the sum, 99 (24.5%) knees showed equivocal, 157 (38.9%) mild, 96 (23.8%) moderate and 52 (12.9%) severe synovitis. Maximum synovitis score was 0 in 8 (2.0%) knees, 1 in 98 (24.3%), 2 in 135 (24.8%) and 3 in 163 (40.3%) knees. Radiographic OA was strongly associated with whole knee synovitis using both definitions of synovitis (ORs 4.4, 95% CI 2.7-7.0 and 3.2, 95% CI 2.0-5.3). A trend was observed for associations of cartilage damage severity and synovitis, albeit not Table 1. Radiographic osteoarthritis and synovitis Kellgren-Lawrence N Adjusted OR (95% CI)* Adjusted OR (95% CI)* status Synovitis Sum Max. Synovitis Score KL = 0 and 1 318 1.0 (Reference) 1.0 (Reference) KL > 1 86 4.4 (2.7, 7.0) 3.2 (2.0, 5.3) KL 2 41 2.5 (1.3, 4.6) 2.3 (1.2, 4.4) KL 3 37 5.9 (3.1, 11.4) 3.7 (1.8, 7.6) KL 4 8 37.9 (7.5, 192.0) 15.4 (1.8, 131.7) *Adjusted for age, gender, body mass index. KL Kellgren-Lawrence, OR Odds Ratio, 95% CI 95% confidence interval, Max. maximum. Table 2. Cartilage status and synovitis Cartilage status N Adjusted Adjusted OR (95% CI)* OR (95% CI)* Synovitis Sum Max. Synovitis score Any cartilage damage (WORMS cartilage morphology score >1) in <4 subregions 208 1.0 (Reference) 1.0 (Reference) Any cartilage damage (WORMS cartilage morphology score >1) in >4 subregions 135 1.6 (1.1, 2.4) 1.4 (1.0, 2.2) 4, 5 subregions 20 1.3 (0.8, 2.2) 1.3 (0.8, 2.2) 6,7 subregions 54 1.7 (1.0, 3.0) 1.4 (0.8, 2.6) ≥8 subregions 61 2.1 (1.1, 4.0) 1.7 (0.9, 3.3) *Adjusted for age, gender, body mass index. KL Kellgren-Lawrence, OR Odds Ratio, 95% CI 95% confidence interval, Max. maximum. Table 3. Meniscus status and synovitis Meniscus status N Adjusted OR (95% CI)* Adjusted OR (95% CI)* Synovitis Sum Max. Synovitis score WORMS grade 0 in all 6 subregions 164 1.0 (Reference) 1.0 (Reference) Max. Meniscus score: ≥ 1 in any subregion 178 1.4 (0.9, 2.1) 1.3 (0.9, 2.0) = 1 in any subregion 83 1.2 (0.5, 2.7) 1.6 (0.7, 3.9) = 2 in any subregion 53 1.0 (0.6, 1.8) 0.9 (0.5, 1.6) ≥ 3 in any subregion 42 2.0 (1.2, 3.5) 1.8 (1.0, 3.1) *Adjusted for age, gender, body mass index. KL Kellgren-Lawrence, OR Odds Ratio, 95% CI 95% confidence interval, Max. maximum. significant. Only severe meniscal damage showed a significant association with synovitis (OR 2.0 95% CI 1.2-3.5). Conclusions: Whole knee synovitis as semiquantitatitvely assessed on T1w CE MRI is strongly associated with TF radiographic OA. Severity of OA is associated with amount of synovitis supporting theories that synovitis might be a secondary phenomenon after joint damage has occurred. Amount of subregional involvement of cartilage damage is not associated with synovitis, albeit a trend could be shown. Severe meniscal damage shows an association with synovitis.