SYNOVIAL THICKENING DETECTED BY MR-IMAGING IN OSTEOARTHRITIS OF THE KNEE CONFIRMED BY BIOPSY AS SYNOVITIS

Previous studies have established the value of magnetic resonance imag ing (MRI) in detecting articular changes characteristic of osteoarthri tis (OA) of the knee. We have observed some MRI features in OA of the knee presumably indicating synovial thickening. To determine whether t hese MR features represent chronic synovial inflammation, we studied t he knees of nine patients at the mild end of the spectrum of OA of rel atively short duration (89%:less than or equal to 4 yr), who were sele cted because MRI showed anatomical abnormalities compatible with synov ial thickening. The painful knee was examined using conventional and w eight-bearing radiographs, MRI, and arthroscopy. MR images suggestive of synovial thickening typically appeared in or near the intercondylar region of the knee, in the infrapatellar fat pad, or in the posterior joint margin. The site of an arthroscopic biopsy of the synovial memb rane was guided by MRI to the area thought to represent synovial thick ening for each patient knee. Pathological examination of these synovia l membrane biopsies showed a mild chronic synovitis, and thus a corres pondence with the synovial thickening detected by MRI. Our results sug gest that MRI can be used to evaluate the extent of synovitis, observe d as synovial thickening, in patients with early OA of the knee.