Assessment of magnetic resonance images of displacement of the disc of the temporomandibular joint in different types of condylar fracture.

Abstract To evaluate the displacement of the disc of the temporomandibular joint (TMJ) in different types of condylar fracture we studied 160 patients (222 joints) from May 2009-June 2014. All patients had computed tomographic scans (CT) and magnetic resonance images (MRI) taken preoperatively, and 24 patients (32 joints) had MRI postoperatively. CT scans were reviewed to categorise the types of condylar fracture (intracapsular, condylar neck, and subcondylar), and intracapsular condylar fractures were further classified into subtypes A, B, C, and M. MRI were then reviewed to record the position of the disc in each type of condylar fracture. The results were compared using the chi square test. There were 160 intracapsular condylar fractures, 40 fractures of the condylar neck, and 22 subcondylar fractures. Of the intracapsular condylar fractures, 75 were type A, 49 type B, 11 type C, and 25 type M. Discs were displaced in 153 intracapsular condylar fractures, 17 fractures of the condylar neck, and eight subcondylar fractures. Among the type A intracapsular condylar fractures, discs were displaced in 71/75, type B in 47/49, type C in 10/11, and in all 25 type M. The incidence of displaced discs between intracapsular condylar fractures on the one hand, and those of the condylar neck or subcondylar region on the other, was significant (p