MR imaging findings in knee osteoarthritis: Correlation with plain films, scintigraphy, and histopathology

Osteoarthritis (OA) is a common disease with a pathogenesis that currently is not well understood. Pathologic alterations involve hyaline cartilage, subchondral cortex, and marrow cavity structures. The authors studied 24 patients with osteoarthritis of the knee with MR imaging and correlation with conventional radiography (all cases; weight-bearing views), scintigraphy (16 to 24), and histopathologic findings (eight of 24; specimens from joint replacement surgery). They found the grade of OA on the MR images to be the same as or one grade more advanced than that on weight-bearing plain radiographs. A frequent zone of decreased signal in the subchondral region on the T1-weighted images usually corresponded to a smaller zone of decreased signal on the T2-weighted images, representing sclerosis and fat replacement by fibrosis surrounded by a reactive zone