However, they remain unavailable for severe osteoporosis. There are several methods to enhance the purchase of screws, such as modifying screw design and strengthening the vertebrae with augmentation materials or the combination of cortical pedicle screw techniques. In addition, screw loosening is known to be a complication of PS fixation, especially in osteoporotic patients. In addition, the PPS technique relies on intraoperative multiplanar fluoroscopy, which leads to high radiation exposure risk for surgeons and patients. While a percutaneous pedicle screw (PPS) technique is an alternative, it requires an additional method of decompression and bone grafting. However, the main defects of the sacral PS fixation are screw loosening and pseudarthrosis, especially in the long-segment surgery and in fixation for osteoporotic patients. Spinal fusion with traditional bilateral PS fixation has been described for a variety of surgical indications, such as spinal canal stenosis, spinal degenerative disc disease, spinal slip, spinal tumor, spinal trauma, and malformations. Pedicle screws (PS) are the most common method of sacral fixation. More importantly, it provides an alternative solution for pelvic fixation. It is a safe and effective means to strengthen lumbar-sacral internal fixation as well as provide additional correction force for patients with lumbar-sacral degeneration, deformity and tumor. In this chapter, we aimed to introduce an original lumbar-sacral strengthening technique, multiple trajectory anchoring(MTA), for lumbar-sacral fusion. Forth, the MTA fixation can not only strengthen the construct, but also provide additional correction force. Third, the MTA screw can provide better stability for the anterior column. Second, the interaction between the multi-trajectory screws anchoring on one vertebra makes the screws stronger and reduce the risk of screw loosening. First, the satellite rods are fixed with the additional screws which makes the tension more dispersed and avoids stress concentration.
The technique comes with the following improvements and advantages.
In this study, we developed a technique combining pedicle screw, cortical bone trajectory screw, and sacral alar screw, which was named as multiple trajectory anchoring (MTA) technique for patients who underwent lumbar-sacral fusion. Cortical bone trajectory (CBT) screw was firstly utilized by Santoni in 2009, which had been proved to have stronger hold force, especially in the osteoporosis vertebrae compared with the pedicle screw (PS).
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