Arthritis & Rheumatism, Volume 60,
October 2009 Abstract Supplement

The 2009 ACR/ARHP Annual Scientific Meeting
Philadelphia October 16-21, 2009.

Anatomical Distribution of Synovitis in Knee Osteoarthritis and Its Association with Joint Effusion Assessed On Contrast-Enhanced MRI

Roemer1,  Frank W., Javaid2,  M. Kassim, Guermazi1,  Ali, Thomas3,  Matthew, Kiran4,  Amit, King5,  Leonard, Keen6,  Richard

Boston University School of Medicine, Boston, MA
University of Oxford, Oxford, United Kingdom
University of Southampton, Southampton, United Kingdom
Oxford University, United Kingdom
University of Southampton, United Kingdom
University College London, United Kingdom


Degenerative joints commonly demonstrate signs of synovitis, even in the early phase of disease, which is thought to be a secondary phenomenon due to damaged intraarticular tissues. Only assessment of synovitis on contrast-enhanced T1-weighted images correlates with microscopically proven synovitis, which is the rationale for using contrast-enhanced MRI. Aim of our study was to describe the distribution of synovial enhancement patterns and presence of joint effusion in patients with radiographic knee osteoarthritis (OA) using a novel comprehensive semiquantitative (SQ) scoring system.


We used the baseline MRI from participants of a randomized treatment trial in knee OA including axial proton density (PD)-weighted (w) fat suppressed (FS), axial T1w FS contrast enhanced (CE) and sagittal T1w FS CE sequences. Synovial enhancement was scored semi-quantitatively from 0–3: 0 = no synovial thickening, 1 = <2 mm (equivocal synovial thickness), 2 = 2–4 mm (moderate synovitis) and 3 >=4mm (severe synovitis). The following 11 subregions were assessed: suprapatellar, infrapatellar, medial parapatellar, lateral parapatellar, intercondylar, around the anterior cruciate ligament (ACL), posterior to the posterior cruciate ligament (PCL), medial perimeniscal, lateral perimeniscal, Baker's cysts and around loose bodies. Maximum synovial enhancement was grouped as absent (grade 0), equivocal (grade 1) and definite (grades 2 and 3). Effusion was scored from 0–3 on PD fs and T1w FS CE sequences according to the amount of capsular distension. We described the distribution of synovitis in the whole cohort and also by effusion status.


111 subjects were included (mean age 64.4 [range 51–81], 64% women, mean body mass index 29.3 [range 21–43]). All knees exhibited at least one subregion with equivocal synovial thickness, 89% of knees had at least one subregion with at least grade 2 and 40% had a maximum grade 3. The commonest sites for definite synovitis were posterior to the PCL in 71% and the suprapatellar region in 60% of all knees. The median number of affected sites with definite synovitis was 3. Overall percent agreement of effusion scored on PD fs and T1w FS CE sequences was 65%, with a weighted kappa of 0.69. On T1w FS CE 73% of knees showed effusion, with 38% of knees exhibiting a grade 2/3 size effusion. Definite synovitis in at least one location was present in 78/81 (96.3%) knees with an effusion and in 21/30 knees (70%) without an effusion.


Disagreement of effusion assessment is due to overestimation of effusion on the PD fs sequence. Definite synovitis was present in the majority of knees without a measurable effusion. Synovitis in OA is common with the commonest site being the region posterior to the PCL. The clinical consequences of synovial enhancement at the different sites need to be explored.

To cite this abstract, please use the following information:
Roemer, Frank W., Javaid, M. Kassim, Guermazi, Ali, Thomas, Matthew, Kiran, Amit, King, Leonard, et al; Anatomical Distribution of Synovitis in Knee Osteoarthritis and Its Association with Joint Effusion Assessed On Contrast-Enhanced MRI [abstract]. Arthritis Rheum 2009;60 Suppl 10 :200
DOI: 10.1002/art.25283

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