MR Imaging Assessment of Temporomandibular Joint Soft Tissue Injuries in Dislocated and Nondislocated Mandibular Condylar Fractures

BACKGROUND AND PURPOSE: Evaluation of temporomandibular joint (TMJ) soft tissue injuries after condylar fractures remains a challenge with use of conventional radiography and CT. The aim of this study was to explore MR imaging in the assessment of TMJ soft tissue injuries after condylar fractures. MATERIALS AND METHODS: Eighty subjects (118 TMJs) with condylar fractures were examined with sagittal and coronal MR imaging. Proton attenuation and T2-weighted sequences were the key sequences in our imaging protocol. All of the condylar fractures were classified into condylar fractures with dislocation (group 1, 108 TMJs) and without dislocation (group 2, 10 TMJs). RESULTS: MR imaging demonstrated the following TMJ soft tissue injuries: 1) disk displacements (91.5%, 105 [97.2%] in group 1 and 3 [30%] in group 2; P < .01). Almost all disk displacements in group 1 were in the anteroinferior direction; 2) abnormal signal intensities of retrodiskal tissues (87.3%, 98 [88.3%] in group 1 and 5 [50%] in group 2; P < .05); 3) joint effusion (85.6%, 95 [88%] in group 1 and 6 [60%] in group 2; P > .05); 4) abnormal inferoposterior attachments of disks (87.3%, 96 [88.9%] in group 1 and 7 [70%] in group 2; P > .05) and joint capsules (85.6%, 94 [87%] in group 1 and 7 [70%] in group 2; P > .05). CONCLUSIONS: There were significant differences of disk displacement and signal intensities of retrodiskal tissues between both fractures. Most dislocated condylar fractures were characterized with anteroinferior disk displacements along with the fractured fragments. MR imaging could provide additional information of TMJ soft tissue injuries after condylar fractures.