Review of currently used classifications for pedicle screw position grading in cervical, thoracic and lumbar spine

Pedicle screw fixation technique has been established as the safe standard for instrumentations in all spinal regions. However, the screw position is sometimes suboptimal. Cortical breaches may occur in different regions of the vertebrae. In addition to compromising bone purchase, pedicle perforations may endanger neural, vascular, and visceral structures. Moreover, a mispositioned screw can result in a greater risk of instrumentation failure. The accuracy of screw insertion has become a frequent topic of recent publications on spine surgery. Despite that, there is no unified way of reporting pedicle screws position. Several different scales are used. Given the multitude of used classifications and rarity of reported complications exact clinical relevance of pedicle screw misplacements remain unclear. In this article, the authors review types of scoring systems and propose a structured way for pedicle screw position grading based on a combination of the most used classifications.