Percutaneous Pedicle Screw Placement Aided by a New Drill Guide Template Combined with Fluoroscopy: An Accuracy Study

Abstract

Objective: To evaluate the accuracy of percutaneous pedicle screw (PPS) placement aided by a new drill guide template.

Methods: The patients were divided into guide template group and conventional perspective group. In the conventional perspective group, the screws were placed by hand under fluoroscopy. In the guide template group, the screw placement was aided by a new drill guide template, and the drill guide template is designed according to the patient's ideal pedicle screw, but not based on skin morphology. The accuracy was evaluated by comparing the following parameters between the two groups: pedicle breach level, inclination angle deviation between the left and right screws, sagittal angle deviation between the left and right screws, and position deviation of the left and right screw entry points. The consistency of the postoperative screw angle and the corresponding guide template inclination angle was compared in the guide template group. The operative time, blood loss, and radiation times were compared between the groups.

Results: A total of 146 patients (876 screws) were enrolled in our study including 79 (474 screws) in the guide template group and 67 (402 screws) in the conventional perspective group. The pedicle breach level in the guide template group (22/474) was significantly lower than that in the conventional perspective group (47/402) (P < 0.05). The position and direction deviations of the left and right screws in the guide template group (2.06 ± 1.02 mm, 1.23 ± 1.25 mm, 1.83° ± 1.49°) were significantly less than those in the conventional perspective group (5.33 ± 2.99 mm, 4.32 ± 3.25 mm, 2.87° ± 1.56°). The operation time, blood loss, and radiation times were significantly lower in the guide template group (80.49 ± 9.14 min, 50.42 ± 8.9 mL, 11.02 ± 2.44) than those in the conventional perspective group (108.1 ± 21.18 min, 71.7 ± 17.09 mL, 23.53 ± 4.54). There were no significant differences between the postoperative screw angle and the corresponding guide template angle in the guide template group.

Conclusion: PPS placement aided by a new drill guide template yielded higher screw accuracy and less operative time, blood loss, and radiation exposure than traditional screw placement.

Keywords: 3D printing technology; Minimally invasive spine surgery; Percutaneous pedicle screw fixation (PPS); Thoracolumbar fractures.

Figure 1

Sketch of the guide template. (A) The front view of the disassembled guide template. (B) The side view of the disassembled guide template.

Figure 2

Measurement of the pedicle inclination angle. (A) The connection between point A and point B is an ideal pedicle screw path in the axial view. The angle between the connection line and the sagittal plane was regarded as the inclination angle. (B) In the anteroposterior view, point A is at the pedicle margin and point B is at the pedicle center.

Figure 3

Surgical procedure simulation in a male patient with an L₁ fracture. (A) Assembly of the guide templates outside the skin. (B, C) Simulation of K‐wire placement under the guide template.

Figure 4

Surgical procedure in the above male patient. (A) The guide template was fixed on the skin surface, and K‐wires were placed through the guide template. (B) The disassembled guide template. (C) The guide template was removed, and the K‐wires are shown. (D) Stitched wound after pedicle screw placement.

Figure 5

Intraoperative C‐arm fluoroscopic images of the above patient. (A, B) After the K‐wires were inserted into the pedicle, the tip of the K‐wire did not exceed the medial margin of the pedicle in the C‐arm fluoroscopy. (C, D) The K‐wires were inserted into the front 1/3 of the vertebral body in lateral fluoroscopy and lateral fluoroscopy. (E‐F) The screw was placed to reduce the fracture and fix the screw.

Figure 6

CT images of the above patient. (A) Postoperative CT axial images of T₁₂. (B) Postoperative CT axial images of L₁. (C) Postoperative CT axial images of L₂.