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Development of an MRI ‐based definition of knee osteoarthritis: Data from the Multicenter Osteoarthritis Study
Journal article   Peer reviewed

Development of an MRI ‐based definition of knee osteoarthritis: Data from the Multicenter Osteoarthritis Study

Jean W. Liew, Gabriela Rabasa, Michael LaValley, Jamie Collins, Joshua Stefanik, Frank W. Roemer, Ali Guermazi, Cora E. Lewis, Michael Nevitt, James Torner, …
Arthritis & rheumatology (Hoboken, N.J.), Vol.75(7), pp.1132-1138
07/2023
DOI: 10.1002/art.42454
PMCID: PMC10361157
PMID: 36693143

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Abstract

Background Although the imaging modality of choice for research, there is no widely accepted MRI definition of knee osteoarthritis. We tested the performance of different definitions. Methods We studied Multicenter Osteoarthritis Study participants with knee symptoms, posterior-anterior and lateral knee radiographs, and MRIs. Radiographic OA (ROA) was defined as Kellgren-Lawrence grade ≥2 in the tibiofemoral (TF) and/or patellofemoral (PF) joint. Symptomatic OA was defined using a validated questionnaire. MRI findings of cartilage damage, osteophytes, bone marrow lesions (BMLs) and synovitis were scored using the WORMS system. We compared definitions using combinations of MRI features to the validation criteria of prevalent ROA and symptomatic OA. All combinations included cartilage damage (score ≥2/6) and osteophyte score ≥2/6; adding BMLs and synovitis was also tested. We also evaluated a Delphi panel definition that defined OA differently for the PF and TF joints. For each definition, we calculated sensitivity, specificity, and the area under the curve (AUC). Results We included 1185 knees (mean age 61 years, 62% female, 89% white). Of these, 482 had ROA and 524 symptomatic OA. The definitions with cartilage score ≥2/6 and osteophyte score ≥2/6 and ones which added to these BMLs or synovitis ≥1 had the highest sensitivities (95.2%) for prevalent ROA (AUC 0.67), and symptomatic OA. The Delphi panel definition had similar performance but was more complex to apply. Conclusion An MRI OA definition requiring cartilage damage and a small osteophyte with or without BMLs or synovitis had the best performance and was simplest for identifying ROA and symptomatic OA.

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