Correlation between clinical diagnosis based on RDC/TMD and MRI findings of TMJ internal derangement

This study was conducted to investigate the value of magnetic resonance imaging (MRI) in the diagnostic process based on the Research Diagnostic Criteria for Temporomandibular Disorder (RDC/TMD) by evaluating agreement between RDC/TMD and MRI diagnosis of disc displacement (DD) and correlation amongst MRI findings such as DD, joint effusion (JE), degenerative change and superior lateral pterygoid muscle (SLPM) attachment. Randomly selected MRIs of 200 joints from 100 TMD patients differentiated into RDC/TMD group II representing DD by clinical examination were reviewed retrospectively. The results show that Cohen's kappa value was 0.336 showing overall disagreement between RDC/TMD group II and MRI diagnoses (P<0.001). The Cohen's kappa value for group IIa, DD with reduction (DDWR), was -0.223 (P<0.01) showing disagreement, whilst the value was 0.546 for group IIb, DD without reduction (DDWOR) with limited opening, and 0.490 for group IIc, DDWOR without limited opening, showing moderate agreement (P<0.001). JE was detected with a higher probability as the state of DD advanced (P<0.001) and when degenerative joint changes were present (P<0.05). The difference of DD according to SLPM attachment was insignificant. MRI could be used when clinical examination cannot predict the true position of the disc.