Abstract
The most common direction of temporomandibular joint (TMJ) disc displacement is anterior. Anterior disc displacement is associated with lateral or medial disc displacement, termed rotational disc displacement (RDD). There have been few systematic studies of the clinical and magnetic resorarce imaging (MRI) findings of TMJs with RDD.
The aim of this study was to assess the prevalence of RDD and to evaluate the relations between the direction of disc displacement (anteromedial RDD, anterolateral RDD, and pure anterior disc displacement) and clinical findings, including joint pain, joint sound, and range of motion, as well as MRI findings, including disc shape, disc reduction, disc mobility, degree of disc displacement, bone changes of the condyle, and degree of condylar translation. The study was based on MRI of 529 TMJs in 409 patients with symptoms and signs of TMJ. Sagittal and coronal T 1-weighted SE images (1.5 Tesla) were used.
MRI showed anteromedial RDD in 96 joints (18.1%), anterolateral RDD in 64 joints (12.1%), and anterior disc displacement in 207 joints (39.1%). There were no statistical differences between anterolateral RDD, anteromedial RDD, and anterior disc displacement with regard to clinical findings. The incidence of reducible disc was higher in anterolateral RDD than in anteromedial RDD or anterior disc displacement. The incidence of bone changes was lower in anterolateral RDD than in anterior disc displacement. There were no significant differences between anteromedial RDD and anterior disc displacement with regard to MRI findings.
In conclusion, anteromedial RDD may represent the same clinical entity as anterior disc displacement, but it remains unclear whether or not anterolateral RDD differs from anteromedial RDD or anterior disc displacement.
