Optimized design strategy of 3D-printed drill guiding template for accurate pedicle screw insertion of subaxial cervical spine

Objective: To propose optimized design strategy of 3D-printed drill guiding template (DGT) for subaxial cervical pedicle screw (CPS) insertion and to evaluate the safety and accuracy of CPS placement. Methods Twenty-two consecutive patients (12 males and 10 females) with a mean age of 50.1 ± 13.4 years (range, 25–79) who underwent 3D-printed DGT-assisted subaxial cervical pedicle screw insertion in our center between August 2016 and October 2020 were retrospectively reviewed. DGTs were individually designed for each patient based on standardized optimal strategies. Accuracy of screw placement was assessed in post-operative CT scanning, and perioperative complications were recorded for each patient. Results A total of 118 CPSs were placed, among which 94.9% (112/118) were considered accurate (90 screws in Grade 0 and 22 screws in Grade 1) and 5.1% (6/118) were misplaced (5 screws in Grade 2 and 1 screw in Grade 3) according to Kaneyama’s method. The direction of CPS perforation (higher than Grade 0) was lateral in 85.7% (24/28), medial in 3.6% (1/28), superior in 3.6% (1/28), and inferior in 7.1% (2/28). Twelve lateral mass screws (LMSs) were inserted as alternative of contraindicated pedicles. No major neuromuscular complications were observed. Conclusion Our optimized design strategy of 3D-printed DGT might help to improve the accuracy and safety for subaxial CPS insertion, and decrease learning curve for spine surgeons, particularly for beginners.