Effect of spatial location of the screw at the injured vertebra on the vertebral height in AO type A thoracolumbar fracture / 中华创伤骨科杂志

ABSTRACT

Objective:To compare the effects of 3 spatial locations of the screw at the injured vertebra on the vertebral height in AO type A thoracolumbar fracture.Methods:A retrospective analysis was performed of the 156 patients with type A thoracolumbar fracture who had been hospitalized at Department of Spine Surgery, The Sixth Hospital of Ningbo from January 2016 to June 2019. They were divided into 3 groups according to the spatial location of the screw at the injured vertebra. In group A of 55 cases, the screws were located in the vertebral body between the longitudinal axis bisector of the vertebral pedicle and the upper endplate; in group B of 52 cases, the screws were located in the vertebral body between the vertical axis bisector of the vertebral pedicle and the horizontal line of the apex of the inferior pedicle notch; in group C of 49 cases, the screws were located in the vertebral body between the horizontal line at the apex of the inferior pedicle notch and the inferior endplate. The anterior, middle and posterior heights of the injured vertebra, Beck index and angulation of the injured vertebra at preoperation, one week postoperation and the last follow-up were compared between the 3 groups and within the same group.Results:There was no significant difference in preoperative general data between the 3 groups, showing comparability ( P>0.05). In all the 3 groups, the anterior and middle heights of the injured vertebra and Beck indexes at one week postoperation and at the last follow-up were significantly larger than those before operation while the angulations of the injured vertebra at one week postoperation and at the last follow-up were significantly smaller than the preoperative values (all P<0.05), but there was no significant difference between one week postoperation and the last follow-up in any of the above indexes ( P>0.05). In all the patients, the posterior height of the injured vertebra at one week postoperation was significantly larger than those before operation and at the last follow-up ( P<0.05), but there was no such a significant difference in comparison between preoperation and the last follow-up ( P>0.05). At the last follow-up, groups A and B had significantly larger anterior and middle heights of the injured vertebra and Beck indexes but significantly smaller angulations of the injured vertebra than group C, but such significant differences did not exist when the above indexes were compared between groups A and B ( P>0.05). Conclusions:In insertion into an injured vertebra, the screw should be parallel and close to the upper endplate, and located in the middle and upper part of the vertebra corresponding to the longitudinal axis of the vertebral pedicle, because this spatial position is conducive to intraoperative reduction, maintaining the postoperative height of the injured vertebra, and decreasing loss of the vertebral height.