Arthrotomographic sign of a 'double line' as an indicator of disc folding and sideways disc displacement in the temporomandibular joint.

Dual-space, single-contrast arthrotomolgraphy of the TMJ was performed on a 19-year-old woman with a history of pain and clicking. Simultaneous multi-layer arthrotomography with computed radiography was used for the present examination. Anterior disc displacement with reduction was observed in the sagittal plane, together with a double line in the lower joint space. The double line was interpreted as disc folding and sideways disc displacement and was confirmed in the coronal plane.