Range of Motion Determined by Multidetector-row Computed Tomography in Patients with Cervical Ossification of the Posterior Longitudinal Ligament

The purpose of this study was to measure range of motion (ROM) in patients with cervical ossification of posterior longitudinal ligament (C-OPLL) by multidetector-row computed tomography (MDCT), and to investigate the influence of dynamic factors. The study included 101 patients with C-OPLL and 99 normal control patients. Preoperative MDCT were taken in all subjects in maximum neck flexion and extension. ROM at each disc level between C2/3 and C7/T1 in sagittal view was measured. Ossification morphology at each disc segment was divided into 6 groups: covered disc, covered vertebra, unconnected vertebra, connected vertebra (continuous), connected vertebra (localized), and others. The relationship between ROM and the group of ossification morphology was also investigated. ROM of adjacent intervertebral disc in connected vertebrae (continuous and localized) and those of others were investigated for each group. The average ROM of covered disc group was significantly higher than that of connected vertebra (continuous, localized). The average ROM of connected vertebra (continuous) group was significantly lower than that of covered disc group, others group, and normal control. There was no significant difference between ROM of adjacent intervertebral disc in connected vertebrae and others, but the average ROM of the connected vertebra group was significantly lower than that of the covered disc group and normal control group. Dynamic factor was reduced at continuous segment, but it was not increased in adjacent intervertebral disc.