QUANTITATIVE 3-DIMENSIONAL ANATOMY OF THE SUBAXIAL CERVICAL-SPINE - IMPLICATION FOR ANTERIOR SPINAL SURGERY

KNOWLEDGE OF THE quantitative anatomy of the subaxial cervical vertebr ae is essential to safely perform anterior cervical surgery and to ens ure adequate decompression of neural structures. In spite of this, lit tle has been published in the neurosurgical literature regarding the s patial relationship of the lower cervical vertebrae and the implicatio ns of this anatomy for anterior cervical surgery. We report the three- dimensional analysis of the mid- and lower cervical spine in in cadave r specimens for 50 disarticulated vertebrae and discuss the relevance of this analysis to surgery in this region. Measurements were made usi ng real-time video analysis of images transferred from a Zeiss microsc ope equipped with an image splitter and a Sony charge-coupled device c amera. Images were then transferred to an IBM personal computer-based image analysis system. Analysis of variance was used to test for signi ficant differences among the C3-C7 vertebral measurements. Important r elationships of the vertebral artery to the anteroposterior diameter o f the vertebral bodies and its variations from C3 to C7 are discussed. The vertebral artery migrates posteriorly to anteriorly from C3 to C6 and posteriorly again at C7; the implications of these variations are discussed for decompression of the neural foramen. Another finding sh owing that the inter-Luschka distance increases from C3 to C7 is impor tant for adequate lateral decompression in anterior cervical spinal su rgery. The pedicle to the Luschka joint was measured at the different levels; the pedicle is lateral to the Luschka joint from C3 to C6 and medial to the joint at C7. This variation explains the lack of root de compression at some cervical levels, even when decompression extends t o the Luschka joint bilaterally. We also report the measurements of th e vertebral bodies and the spinal canal and compare the results with o ther published data. We think these measurements provide guidelines fo r operating on the anterior cervical spine, facilitate adequate decomp ression of the spinal cord and neural foramen, and increase the margin of safety of the surgeon.