Further evidence that a cartilage-pannus junction synovitis predilection is not a specific feature of rheumatoid arthritis

Background: Qualitative differences in synovitis between the cartilage-pannus junction (CPJ) region and the adjoining suprapatellar pouch (SPP) have been reported in rheumatoid arthritis and the spondyloarthropathies. Objective: To determine if the distribution of synovitis is the same in osteoarthritis (OA) using sensitive measures of inflammation derived from dynamic, contrast enhanced magnetic resonance imaging (DEMRI). Methods: 20 subjects with established OA of the knee were recruited. Conventional MR images together with the DEMRI measurements were obtained. Areas of synovitis at the CPJ region and at a distant site in the SPP were calculated; differences in CPJ and SPP synovitis were determined using DEMRI parameters: the initial rate of contrast enhancement (IRE) and maximal enhancement (ME). Results: The area of synovitis was significantly greater adjacent to the CPJ than in the SPP. IRE and ME measures were greater at the CPJ than the SPP. Conclusions: The magnitude of synovitis at the CPJ is not disease-specific and applies across the spectrum of degenerative disease as well as inflammatory diseases.