Interspinous distance

Anterior dislocation of the cervical spine may be detected reliably in the supine frontal projection by evaluating the cervical spinous processes. A widened interspinous distance (ISD) which measures more than one and one-half times the ISD above and more than one and one-half times the ISD below indicates the presence of an anterior cervical dislocation at the level of abnormal widening. Measurements of the interspinous distances from the C3-C4 interval through the C7-T1 interval in 500 patients with normal cervical spines and in 14 patients with documented anterior cervical dislocations revealed neither false positive nor false-negative diagnoses by these criteria ¹⁾.

On plain radiographs, a decrease of 50 percent in vertebral body height, an increase of interspinous distance, and greater than 30 to 35 degrees of kyphotic deformity are suggestive of posterior ligament complex injury.