Sagittal orientation and uniform entry for thoracic pedicle screw placement with free-hand technique: A retrospective study on 382 pedicle screws

One of the most important factors in obtaining a successful outcome in spinal surgery is appropriate placement of the pedicle screw. A number of different techniques are used to achieve successful pedicle screw placement. The free-hand technique has the advantage of no requirement for radiation exposure, but its success is highly dependent on surgeon experience. Here, we describe our entry point and perioperative sagittal orientation method, and evaluate postoperative sagittal alignment of pedicle screws with the free-hand pedicle screw placement technique.Eighty-two patients undergoing spinal surgery between 2015 and 2016 were included in this study. Pedicle screw placement was evaluated retrospectively on postoperative anterior-posterior (A-P) and lateral load-bearing radiographs of the entire spinal column. The vertebral body was divided into five areas in the lateral plane. Sagittal orientation of the pedicle screws on lateral radiographs was evaluated by two spine surgeons with 3 years of experience and one radiologist experienced in musculoskeletal radiology, with each observer evaluating the image twice according to a 1-month interval.A total of 382 pedicle screws were evaluated. There was no statistically significant difference between the first and second measurements, performed by individual observers, and there was good concordance among the three observers.Use of a uniform entry point at all levels may increase the effectiveness of the free-hand technique and decrease the pedicle screw misplacement rate. Our technique may standardize the free-hand technique, which does not require radiation exposure, and make it more practical to apply uniformly.