Abstract
The use of cervical pedicle screws as anchors in posterior reconstruction surgery has not been widely accepted due to the neurological or vascular injury. We thus sought to investigate the accuracy of free-handed pedicle screw placement in the cervical and upper thoracic spine at the early stage of clinical application.
Eight patients (five males and three females) were included in this study. Mean age was 63 years (31 to 78 years). There were three patients with rheumatoid arthritis, three with cervical fracture-dislocation, and two with spinal metastasis. Twenty-four pedicle screws (3.5 mm diameter: Vertex, Medtronic Sofamordanek) were placed into the pedicle from C2 to T2 level by free-handed technique2). Grade of breaching of pedicle cortex was divided into four groups (Grade 0–3). In addition, screw axis angle (SAA) were calculated from the horizontal and sagittal CT images and compared with pedicle transverse angle (PTA). Furthermore, perioperative complications were also examined.
Our free-handed pedicle screw placement with carving technique is as follows: A longitudinal gutter was created at the lamina-lateral mass junction and then transverse gutter perpendicular to the longitudinal gutter was made at the lateral notch of lateral mass. The entry point of the pedicle screw was on the midline of lateral mass. Medial pedicle cortex through the ventral lamina was identified using the probes to create the hole within the pedicle. The hole was tapped and the screw was gently introduced into the pedicle to ensure the sagittal trajectory using fluoroscopy. In the transverse direction, 22 out of 24 screws (92%) were entirely contained within the pedicle (Grade 0). In contrast, only teo screws (8%) produced breaches less than half the screw diameter (Grade 1). In the sagittal direction, all screws were within the pedicle (Grade 0). Screw trajectories were not consistent with anatomical pedicle axis angle; the mean SAA were smaller than the mean PTA at all levels. The pedicle diameter ranged from 3.9 to 9.2 mm. The mean value gradually increased toward the caudal level. There were no neurological and vascular complications related to screw placement.
