Cortical Bone
Cortical Bone Trajectory Screws for Middle Upper Thoracic: a Anatomico-Radiological Study
Introduction
Pedicle screw fixation system has been widely used in spinal surgery due to its biomechanical advantage in three-dimensional fixation and short-segment fixation. However, Complications such as screw loosening, pullout and broken, often lead to loss of surgical construct stability, particularly in patients with poor bone quality [1-4].
The cortical bone trajectory (CBT)[5] technique is a theoretical benefit to the fixation of osteoporotic vertebrae which involves maximizing the thread contact with the high density bone surface. CBT screw obtains 4-point fit between the dorsal cortex at the site of insertion, the medially oriented posterior pedicle wall, …show more content…
Different pedicle screw technique had different starting point. For example, the starting point of straight-forward located at middle line of inferior articular facet and upper border of transverse process[24, 25]; the “in-out-in” technique utilizes a far lateral starting point on the posterior cortex of the transverse process[26]; the funnel technique created a hole in transverse process as starting point[27-30]. The morphometry of the thoracic pedicle was various[19, 20]. With regard to anatomic variability, the starting point may vary for the various levels of the thoracic spine. The free hand technique with mutative start point was credible which got the excellent accuracy of insert screw[29, 31-33]. So we chose starting point of the free hand technique as reference. Because of the CBT screw needed medial to lateral and caudocephalad angle, compared to the free hand technique, the starting point of CBT moved medial and cephalad. It meant less tissue dissection and retraction for reduced muscle disruption. The CBT screw technique was a minimally invasive surgery. Finally, with our starting point, there was a low incidence of pedicle violation
Introduction
Pedicle screw fixation system has been widely used in spinal surgery due to its biomechanical advantage in three-dimensional fixation and short-segment fixation. However, Complications such as screw loosening, pullout and broken, often lead to loss of surgical construct stability, particularly in patients with poor bone quality [1-4].
The cortical bone trajectory (CBT)[5] technique is a theoretical benefit to the fixation of osteoporotic vertebrae which involves maximizing the thread contact with the high density bone surface. CBT screw obtains 4-point fit between the dorsal cortex at the site of insertion, the medially oriented posterior pedicle wall, …show more content…
Different pedicle screw technique had different starting point. For example, the starting point of straight-forward located at middle line of inferior articular facet and upper border of transverse process[24, 25]; the “in-out-in” technique utilizes a far lateral starting point on the posterior cortex of the transverse process[26]; the funnel technique created a hole in transverse process as starting point[27-30]. The morphometry of the thoracic pedicle was various[19, 20]. With regard to anatomic variability, the starting point may vary for the various levels of the thoracic spine. The free hand technique with mutative start point was credible which got the excellent accuracy of insert screw[29, 31-33]. So we chose starting point of the free hand technique as reference. Because of the CBT screw needed medial to lateral and caudocephalad angle, compared to the free hand technique, the starting point of CBT moved medial and cephalad. It meant less tissue dissection and retraction for reduced muscle disruption. The CBT screw technique was a minimally invasive surgery. Finally, with our starting point, there was a low incidence of pedicle violation