Posterior Spinal Screw Fixation Techniques and Trajectories: General Overview and an Analysis of How Often They Are Used

Abstract

Abstract Background: There is a great variety of techniques (translaminar, transfacet, and extrapedicular screws) apart from the traditional pedicle screw in posterior spinal instrumentation. The latter technique is the most widely used around the world (except from the cervical region) since it tends to obtain very good results with a simple approach with fewer complications.Therefore, other trajectories are usually reserved for more specific cases in which the insertion of these purely pedicle screws is not possible. Objective: The objective of this study was to review and analyze the use of different techniques and trajectories of posterior spinal instrumentation by different spinal surgeons around the world. Material and Methods: We developed a survey including posterior spinal screw techniques and trajectories. In this article, we present the data resulting from 122 answers from different spinal surgeons (neuro, orthopedic surgery). Results: Despite advances in the development of new technologies such as neuronavigation (17%) and robotic (1%) available on the market, nowadays, the gold-standard technique for spinal screw insertion is the fluoroscopy-assisted freehand approach (54%). The lumbar spine is the most instrumented spinal region (31%), with a clear preference for purely transpedicular screws. Thoracic and sacroiliac areas presented a greater diversity of screw trajectories. In the cervical spine, there is a clear tendency toward the insertion of lateral mass screws (85% in the atlantoaxial region and 70% in the subaxial region), as opposed to the use of pedicular screws. This is mainly due to the complexity of this area and the risk of damaging important neurovascular structures relatively close to the pedicles. Unexpectedly, two additional techniques were presented: cortical bone trajectory for lumbar screw fixation (for osteoporotic patients) and S2-alar-iliac screw fixation (more used than iliac screws alone). Conclusions: This survey demonstrates that the most used spinal trajectory in the thoracolumbar spinal region is the traditional pedicle screw insertion. Lateral mass was the most common place to insert screws in the subaxial cervical region. The use of robotic systems can improve the position of the screws of more complex techniques. We consider that the different techniques should be known since every surgery will be adapted to the patient’s anatomy and needs.