Introduction <p>Screws mispositioning is an identifiable cause of intraoperative neurophysiological monitoring changes. To prevent screw mispositioning, a patient-specific guiding template for pedicle screw positioning (PSGT) was introduced to avoid implant mispositioning. The study aims to compare the changes in neurophysiological monitoring and screw mispositioning between free-hand (FH) and PSGT in patients surgically treated for adolescent idiopathic scoliosis (AIS).</p> Materials and methods <p>All patients treated between January 2016 and December 2021 for AIS surgery, aged 14 to 20, were included in the study. Patients with syndromic, kyphoscoliosis, or neuromuscular scoliosis were excluded from the study. Screws were positioned either with FH or PSGT technique. During and after screws' positioning, holes and screws were tested with neurophysiological monitoring in both cases. All screw misplacements were recorded. Screws misplacements were analyzed with rate, and the comparison between groups was performed through Fisher's exact test.</p> Results <p>According to the inclusion and exclusion criteria, 83 (19 males and 64 females) patients with AIS were included. Some neurophysiological changes were reported in 16.9% of patients (13 transitory, 1 persistent). In 20% of patients treated with the FH technique, some alterations were reported (9 transitory, 1 persistent), while in the PSGT group, alterations were reported in 12% of cases (4 transitory). In 75% of cases, screw mispositioning was recorded in the concavity. No significant differences were observed between groups (<i>p</i> = 0.428).</p> Conclusions <p>Screws mispositioning is one of the significant risks in AIS surgery, and the use of PSGT reduces the incidence of screws mispositioning and neurophysiological changes. However, some alterations were also observed when pedicle screws were implanted with PSGT. Neurophysiological monitoring is essential for verifying screw mispositioning, regardless of the surgical technique employed.</p>