Motion Characteristics of the Functional Spinal Unit During Lumbar Disc Injection (Discography) Including Comparison Between Normal and Degenerative Levels.

Disc injection expands the disc space inducing endplate motion, pedicle motion, and facet translation in almost all normal and most degenerate levels. Disc injection therefore biomechanically "provokes" the entire functional spinal unit. When provoked pain is encountered during lumbar discography, contribution from the associated facet joint and myotendinous insertions should be considered.