OSTEOARTHRITIS OF THE KNEE - CORRELATION OF SUBCHONDRAL MR SIGNAL ABNORMALITIES WITH HISTOPATHOLOGIC AND RADIOGRAPHIC FEATURES

Subchondral signal abnormalities are often present on magnetic resonan ce (MR) images of patients with osteoarthritis, but no study correlati ng these changes with histopathology has been published. We selected n ine consecutive patients with clinical and radiographic diagnosis of m oderate to severe osteoarthritis of the knee scheduled to undergo join t replacement surgery, and performed MR imaging and conventional radio graphs preoperatively. After surgery, the resected portions of the fem ur and tibia underwent gross and microscopic examination, and the find ings were correlated with the corresponding findings on the imaging st udies. Subchondral MR signal abnormalities of the femur or tibia were present in seven of the nine patients, with intermediate signal on T1- weighted images and low or isointense signal on T2-weighted images. Th e subchondral signal abnormalities were hemispherical in configuration and corresponded predominantly to fibrous tissue replacing the fatty marrow. A component of tragbecular thickening was also present.