Anatomical projection of the cervical uncinate process in ventral, ventrolateral, and posterior decompressive surgery.

OBJECT The cervical uncinate processes (UPs), their variations, and the relationships between the neurovascular structures and surrounding bone were investigated in this anatomical study. The object of this study was to highlight the important surgery-related considerations associated with ventral, ventrolateral, and posterior decompressive surgery. METHODS Forty-nine adult C3-7 dry bone samples were used, and 10 measurements were obtained for each vertebra. The anterior measurements involved the cervical uncinate process (UP): height, width, length, distance between its tip and vertebral foramina, interuncinate process distance, sagittal angle with the superior margin of the vertebral body (VB), VB anteroposterior diameter, and VB width. Posterior measurements involved the vertical distance between the superior border of the lamina at the lamina-facet joint and the tip of the UP, as well as the horizontal distance between the medial-most border of the superior facet and the tip of the UP. All symmetrical structures were measured bilaterally. There were no statistically significant differences between right- and left-sided measurements in this series. The height of the UP increased gradually at each segmental level between C-3 and C-7. The width of the UP did not change with segmental level (5.0 mm at C-3 compared with 5.3 mm at C-7). On average, the length of the UP was relatively constant. The distance from the tip of the UP to vertebral foramina averaged 1 mm at the C2-3 level and 1.5 mm at the C5-6 level. Interuncinate distance and VB width gradually increased and were highly variable, which appeared to be related with osteophyte formation. There was a slight gradual increase from C-3 to lower segments, and it paralleled with the midline anteroposterior diameter of the same VB. The angle between the UP and the superior margin of the VB exhibited great variety. The posterior measurements decreased gradually from C-3 to C-7. CONCLUSIONS Based on the data obtained in this study, a surgeon is provided with a three-dimensional orientation as well as anatomical knowledge. This knowledge also allows for a more effective neurovascular decompression by minimizing the surgery-related complications.