Fig. 1.

Measurements according to the digital radiographic measurement method: The anterior and posterior disc heights are measured relative to the anterior vertebral body height, and olisthesis relative to the vertebral body antero-posterior depth. The disc heights are measured at a 90° angle to a straight line going through the two lower corners of the vertebra above. The olisthesis is measured from the posterior disc height line to the posterior corner of the vertebra above