Accuracy of Percutaneous Pedicle Screw Insertion Technique with Conventional Dual Fluoroscopy Units and a Retrospective Comparative Study Based on Surgeon Experience

Abstract

Study Design Retrospective comparative study. Objective To evaluate the accuracy of percutaneous pedicle screw (PPS) placement and intraoperative imaging time using dual fluoroscopy units and their differences between surgeons with more versus less experience. Methods One hundred sixty-one patients who underwent lumbar fusion surgery were divided into two groups, A (n = 74) and B (n = 87), based on the performing surgeon's experience. The accuracy of PPS placement and radiation time for PPS insertion were compared. PPSs were inserted with classic technique under the assistance of dual fluoroscopy units placed in two planes. The breach definition of PPS misplacement was based on postoperative computed tomography (grade I: no breach; grade II: <2 mm; grade III: ≤2 to <4 mm). Results Of 658 PPSs, only 21 screws were misplaced. The breach rates of groups A and B were 3.3% (grade II: 3.4%, grade III: 0%) and 3.1% (grade II: 2.6%, grade III: 0.6%; p = 0.91). One patient in grade III misplacement had a transient symptom of leg numbness. Median radiation exposure time during PPS insertion was 25 seconds and 51 seconds, respectively (p < 0.01). Conclusions Without using an expensive imaging support system, the classic technique of PPS insertion using dual fluoroscopy units in the lumbar and sacral spine is fairly accurate and provides good clinical outcomes, even among surgeons lacking experience.

Keywords: accuracy; dual fluoroscopy units; percutaneous pedicle screw; radiation exposure; surgeon experience.

Fig. 1

The classic technique of pedicle screw insertion using fluoroscopy. Point A is the needle insertion point, and the tip is located on the lateral margin of the pedicle on the perfect anteroposterior view. Point B shows that the tip of the needle has reached the vertebral body, and it should be within the medial margin of the pedicle on the anteroposterior view.

Fig. 2

The distribution of screw misplacement and the grading scale. Most screws are installed at L4 and L5. The highest ratio of screw deviation is seen at L2, and grade III perforations are seen only at L5 and S1.

Fig. 3

The direction of pedicular breaches is shown for the two groups. Lateral breaches are the most common in the two groups. The numbers in parentheses in group B represent grade III misplacements.

Fig. 4

The computed tomography shows lateral breach of screw due to the hypertrophy of facet and the recess in the lateral pedicular wall.