Background Synovitis in osteoarthritis (OA) is thought to be a secondary phenomenon related to intraarticular tissue damage including the meniscus.
The most frequent location of meniscal damage is the posterior horn of the medial meniscus, and nearby anatomical synovitis locations include perimeniscal synovitis and synovitis posterior to the posterior cruciate ligament (PCL). The latter is the most prevalent site of synovitis in OA knees1.
Objectives Aim was to assess the cross-sectional associations of posterior horn meniscal damage with posterior perimeniscal synovitis, and with synovitis posterior to the PCL using contrast enhanced (CE) MRI as only assessment of synovitis on CE MRI correlates with microscopically proven synovitis2.
Methods The Multicenter Osteoarthritis (MOST) Study is a longitudinal observational study of subjects with or at risk for knee OA. Subjects are a subset of MOST who were examined with CE MRI at the 30 months visit and had whole-knee synovitis and meniscal readings available. Synovitis was assessed semiquantitatively (scored 0-2) at 11 different locations according to a validated scoring system including the sites around the medial and lateral posterior horns (=perimeniscal medial/lateral) and posterior to the PCL. A synovitis score ≥1 was defined as synovitis presence in an individual location. A separate analysis was performed looking at severe (=grade 2) synovitis only.
Meniscal damage of the posterior horns was scored according to WORMS from 0-4. Logistic regression was used to assess the association of perimeniscal synovitis (outcome) and posterior meniscal damage in the same compartment (predictor). In addition we examined the association between synovitis posterior to the PCL (outcome) and perimensical damage (predictor). Adjustment was performed for age, gender, radiographic OA and body mass index.
Results 377 knees were included (mean age 61.1 years±6.9, mean BMI 29.6±4.9, 44.3% women). The odds for any ipsi-compartmental perimensical synovitis were increased for knees with medial posterior horn meniscal damage (adjusted odds ratio [aOR] 2.5, 95% confidence intervals [95% CI] 1.3,4.8), but not for lateral damage (aOR 1.7, 95%CI 0.4,6.6). The odds for severe perimensical synovitis were markedly increased for both, medial (aOR 3.8, 95%CI 1.1,13.0) and lateral (aOR 5.4, 95%CI 1.3,22.7) posterior meniscal damage. No positive associations were found for presence of any synovitis posterior to the PCL (aOR 0.9, 95%CI 0.6,1.5) for knees with posterior horn meniscal damage using knees without posterior meniscal damage as the reference.
Conclusions Posterior perimeniscal synovitis is associated with ipsi-compartmental damage of the posterior horn suggesting that local structural damage may cause synovitis nearby. No associations were found for posterior horn meniscal damage with synovitis posterior to the PCL. This suggests that presence of synovitis posterior to the PCL is likely to be triggered by different pathomechanisms than meniscal damage.
Roemer FW, et al. Osteoarthritis Cartilage. 2010;18:1269-74.
Loeuille D, et al. Osteoarthritis Cartilage. 2011;19:1433-9.
Disclosure of Interest F. Roemer Shareholder of: Boston Imaging Core Lab (BICL),LLC., Consultant for: Merck Serono, NIH, D. Felson: None Declared, T. Yang: None Declared, J. Niu: None Declared, M. Crema Shareholder of: Boston Imaging Core Lab (BICL),LLC., M. Englund: None Declared, M. Nevitt: None Declared, Y. Zhang: None Declared, J. Lynch: None Declared, G. El Khoury: None Declared, C. Lewis: None Declared, A. Guermazi Shareholder of: Boston Imaging Core Lab (BICL),LLC., Consultant for: Astra Zeneca, Genzyme, Novartis, Stryker, Merck Serono
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