As many as seven types of disc displacement have been described in MR imaging of symptomatic TM joints. Werther, et al demonstrated that 74% of disc displacements fall into the two most common groups, anterior (45%) and medial rotary ((29%). Of the options listed lateral disc displacement is the least common, occurring in 2.5% of symptomatic joints. Similarly, Simmons found no case of lateral disc displacement in 58 symptomatic joints imaged with MRI.
- Anterior displacement: 44%
- Antero-lateral: 29%
- Antero-medial: 6%
- Lateral: 3%
- Medial displacement: 1%
