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.