Fig. 2

Diagram showing the measurements made on the disc and intervertebral foramen. D-F (disc-to-facet distance), the vertical distance between the apex of the superior articular process and posterior margin of the involved disk; FH (foraminal height), the maximum distance between the inferior margin of the pedicle of the superior vertebra and the superior margin of the pedicle of the inferior vertebra; PDH (posterior disc height), the distance between the posterior ends of the upper and lower endplates at the disc space; FA (foraminal area), area surrounded by blue solid line