[Comparison of two techniques of the transarticular screw placement in the lower cervical spine]

To compare two techniques of the transarticular screw placement in the lower cervical spine, and to suggest and confirm a new technique of the placement.

The techniques of transarticular screw placements used by Takayasu (group A) and Dalcanto (group B) were applied in eight cervical specimens. The splits of facets,the encroachment of the cervical nerve roots and transverse foramens were observed and analyzed. The numbers of transarticular screws which not gone through the facets were counted in both group A and B, respectively.

Sixty-four transarticular screws were implanted,thirty-two for group A, the same for group B. Although no splits of the facets were seen in group A, two transarticular screws did not go through the facets. There were ten splits of facets in group B, in which seven involved the inferior border of the inferior facets and three for the lateral border. No superior facets were found to be broken both in group A and B. Eight screws encroached the transverse foramens in group A and none in group B. Eleven of anterior branch and eight of posterior branch of lower cervical nerve roots were involved in group A, two and nine respectively in group B.

There are high risk of injury of anterior branch of cervical nerve root and vertebral artery if the screws are too long and the Takayasu's technique is used. However, the rate of facet split is high if the Dalcanto's technique is applied.