Analysis of the uncinate processes of the cervical spine: an anatomical study.

OBJECT: Although the uncovertebral region is neurosurgically relevant, relatively little is reported in the literature, specifically the neurosurgical literature, regarding its anatomy. Therefore, the present study aimed at further elucidation of this region's morphological features.

METHODS: Morphometry was performed on the uncinate processes of 40 adult human skeletons. Additionally, range of motion testing was performed, with special attention given to the uncinate processes. Finally, these excrescences were classified based on their encroachment on the adjacent intervertebral foramen.

RESULTS: The height of these processes was on average 4.8 mm, and there was an inverse relationship between height of the uncinate process and the size of the intervertebral foramen. Degeneration of the vertebral body (VB) did not correlate with whether the uncinate process effaced the intervertebral foramen. The taller uncinate processes tended to be located below C-3 vertebral levels, and their average anteroposterior length was 8 mm. The average thickness was found to be 4.9 mm for the base and 1.8 mm for the apex. There were no significant differences found between vertebral level and thickness of the uncinate process. Arthritic changes of the cervical VBs did not necessarily deform the uncinate processes. With axial rotation, the intervertebral discs were noted to be driven into the ipsilateral uncinate process. With lateral flexion, the ipsilateral uncinate processes aided the ipsilateral facet joints in maintaining the integrity of the ipsilateral intervertebral foramen.

CONCLUSIONS: A good appreciation for the anatomy of the uncinate processes is important to the neurosurgeon who operates on the spine. It is hoped that the data presented herein will decrease complications during surgical approaches to the cervical spine.