MR FEATURES OF OSTEOARTHRITIS OF THE KNEE

A group of patients with idiopathic osteoarthritis (OA) of the knee wa s surveyed using weight-bearing radiographs and MR imaging to compare the relative value of these methods in disease evaluation. Fifty-two p atients with a clinical and radiological diagnosis of OA of the knee o f relatively short duration (87%: less than or equal to 4 yr) were com pared to a reference group of 40 age- and sex-comparable subjects with no knee symptoms. AH patients had a complete history, physical examin ation, standard anterior-posterior and lateral weight-bearing radiogra phs, T-1-weighted, and FLASH MR images in both knees. The prevalence o f MRI abnormalities was significantly greater in patients with OA of t he knee in all radiographic grades (Kellgren and Lawrence) compared to the reference subjects. Significant differences were encountered for synovial thickening (OA, 73%; reference, 0%), synovial fluid (60%; 7%) , meniscal degeneration (52%; 7%), osteophytes (67%; 12%), and subchon dral bone involvement (65%; 7%), even in the patients at the mild end of the osteoarthritic spectrum, indicating the exquisite sensitivity o f MRI compared with weight-bearing radiographs.