MR grading of temporomandibular joint fluid: association with disk displacement categories, condyle marrow abnormalities and pain

The purpose of this study was to investigate temporomandibular joint (TMJ) effusion on magnetic resonance (MR) images, and its association with specif ic categories of disk displacement, bone marrow abnormalities and pain. Fro m a series of 523 consecutive TMJ MR imaging studies of patients referred t o imaging because of pain and dysfunction, those with TMJ effusion, defined as an amount of fluid that exceeded the maximum amount seen in a control g roup of asymptomatic volunteers, were analysed. The selected patients were reassessed and the amount of TMJ fluid was graded bilaterally according to a set of reference films. Other parameters recorded included disk displacem ent categories and condyle marrow abnormalities. Pain self-records were obt ained from the patients immediately before MR imaging. The association betw een the recorded parameters and TMJ pain was analysed with t-tests and regr ession analysis. Of the 523 patients, 70 (13%) had TMJ effusion, which was unilateral in 61%. Only 9% of the 70 patients had effusion bilaterally, whe reas bilateral disk displacement was found in 80%. In the 76 joints with ef fusion, 83% showed two specific categories of disk displacement at closed m outh. Condyle marrow abnormalities were found in 31% of the 70 patients, mo stly on one side, and in 24% of the 76 joints. An in-patient regression ana lysis of the side difference in TMJ pain showed that effusion and condyle m arrow abnormalities were significant pain-increasing factors. In conclusion , patients with TMJ effusion represent a subgroup with pain and dysfunction with more severe intra-articular pathology than those with disk displaceme nt but no other joint abnormalities.