Internal Derangement of TMJ: Disc displacement with/without reduction & Wilkes classification

Internal derangement of TMJ is a disruption of the internal aspects of the TMJ, in which an abnormal relationship exists between the disc and the condyle, glenoid fossa and articular eminence. Disc displacement can be subdivided as with and without reduction. Anteromedial displacement of disc is more common. A better understanding of the TMJ anatomy and functions aids in understanding the pathophysiology of disc derangement better. Wilkes classification describes the various stages of disc derangement and associated symptoms clinically and radiologically.