Ali Guermazi MD, Presenter: Stockholder, Synarc Inc

David J. Hunter, Abstract Co-Author: Nothing to Disclose

Frank W. Roemer MD, Abstract Co-Author: Nothing to Disclose

Jingbo Niu, Abstract Co-Author: Nothing to Disclose

Chrisitne E. McLennan MSc, Abstract Co-Author: Nothing to Disclose

David T. Felson, Abstract Co-Author: Nothing to Disclose

Little data exist on the prevalence of MRI findings in normal knees. The purpose of this study is to identify the prevalence and severity of cartilage defects, meniscal lesions and other abnormalities by MRI among participants in the Framingham study with normal knee radiographs.

972 knees in 972 participants (554 females) aged 62.8 + 8.5 years (47, 90) had absent radiographic OA defined as a Kellgren-Lawrence grade of 0 in the tibiofemoral compartment on PA view and no patellofemoral OA on a lateral radiograph. Knee MRIs were read by 2 trained radiologists using a semi-quantitative scoring method for assessing the presence and severity of cartilage, meniscal and ligament lesions, osteophytes, subarticular bone marrow edema and cysts, bone attrition, and synovitis. For each of these features, we defined MRI abnormalities in 2 ways: (1) any score > 0 and (2) ‘unequivocal abnormalities’ (score > 2 or 3 depending on the feature). Inter-reader ICCs for both compartment-specific and total knee scores for all features ranged from 0.59 to 0.93.

Using a score of >0 for a feature, in males/females, 95%/95.2% knees had an overall score >0, 70.5%/68.8% cartilage lesions, and 91.2%/90.2% osteophytes. 34.2%/15.9% had one or more meniscal tears, 50.6%/52.3% bone marrow edema, 23.5%/25.4% bone cysts and 34.7%/30.6% synovitis, 10%/6.9% torn ligaments and 31.4%/27.4% bone attrition. For ‘unequivocal abnormalities’ in males/females, we found cartilage lesions in 43.3%/46.3%, osteophytes in 14%/10%, meniscal tears in 13%/5.5%, bone marrow edema in 15.8%/16.5%, bone cysts in 3.8%/4.3%, ligament tear in 3.3%/0.8%, synovitis in 5.1%/2.3%, bone attrition in 8%/8.5%, and an at least one ‘unequivocal abnormality’ in 55.8%/52.7%.

MRI revealed signs of early OA in the majority of knees in participants without any signs of radiographic OA. Most normal knee radiographs in older persons have a constellation of MRI abnormalities suggestive of early structural OA.

MRI is much more sensitive for the detection of early OA features in comparison to radiography, which might ultimately be of relevance in defining subpopulations for disease-modifying interventions.

Guermazi, A, Hunter, D, Roemer, F, Niu, J, McLennan, C, Felson, D, What Is the Prevalence of Different MRI Features of Knee Osteoarthritis (OA) in Persons with Normal Knee Radiographs?.  Radiological Society of North America 2007 Scientific Assembly and Annual Meeting, November 25 - November 30, 2007 ,Chicago IL. http://archive.rsna.org/2007/5013397.html