Personalized Three-Dimensional Printing Pedicle Screw Guide Innovation for the Surgical Management of Patients with Adolescent Idiopathic Scoliosis

Abstract

Objective: To assess the safety and efficacy of patient-specific three-dimensional (3D) rapid-prototype printing technology for pedicle screw insertion in patients with adolescent idiopathic scoliosis (AIS).

Methods: The 3D pedicle screw guides were produced after selecting the fixation points for all individual levels to be used intraoperatively. Preoperative computed tomography images recreated 3D bone models of each vertebra specific to each patient. Safe pedicle trajectories were determined in all 3 planes on these models. 3D printed guides were modeled according to these trajectories and manufactured with a biocompatible material. Postoperatively, all screws were evaluated and scored with computed tomography as class 1 (accurate), class 2 (inaccurate), or class 3 (deviated). The mean angle between the inserted pedicle screw and the intended trajectory, and the mean distance between the central longitudinal axis of a screw and pedicle were also measured.

Results: A total of 134 screws were inserted. On the concave and convex sides, the mean medial malposition was 0.5 ± 0.8 and 0.4 ± 0.6 mm, the mean lateral malposition was 1.4 ± 2.3 and 0.8 ± 1.3 mm, angle between the inserted pedicle screw and the intended trajectory was 4.2 ± 4.6 and 4.3° ± 6.0°, and distance between the central longitudinal axis of a screw and pedicle was 1.5 ± 2.1 and 0.9 ± 1.2 mm, respectively. A total of 117 screws were regarded as class 1, 14 as class 2, and 3 as class 3. Of all screws inserted, 92.5% achieved positional accuracy. There were no screw-related complications.

Conclusions: This is one of the initial reports to note the novel design and implementation of patient-specific 3D pedicle screw guides for adolescent idiopathic scoliosis surgery. Our pilot study shows that the use of these low-cost personalized 3D guides is completely safe and effective in both convex and concave sides of the curves.

Keywords: 3D printing; Adolescent idiopathic scoliosis; Deformity; Pedicle screw; Spine.