Reduction in CT scan number with the reference frame middle attachment method in intraoperative CT navigation for adolescent idiopathic scoliosis

Purpose Elucidate whether it is preferable to use the reference frame (RF) middle attachment (RFMA) method over the edge of the planned pedicle screw (PS) insertion area for RF placement in the surgery for adolescent idiopathic scoliosis (AIS) with intraoperative computed tomography (CT) navigation. Methods Eighty-six consecutive patients (76 female and 10 male; mean age: 15.9 years) with AIS who underwent posterior spinal fusion using intraoperative CT navigation were enrolled. The group with the RF placed at the most distal part of the CT scan range was defined as the distal group (Group D), with other placements classified into the middle group (Group M). PS perforation rate and surgical outcome were compared between the groups. Results There was no significant difference in perforation rate between Group M and Group D (3.4% vs. 3.0%, P = 0.754). The mean ± standard deviation number of instrumented vertebrae at the first CT scan was significantly higher in Group M (8.2 ± 1.2 vs. 6.3 ± 1.2, P < 0.001), while mean blood loss was significantly lower (266 ± 185 mL vs. 416 ± 348 mL, P = 0.011). The frequency of needing a second CT scan for PS insertion was significantly lower in Group M (38% vs. 69%, P = 0.04). Conclusion The RFMA method in thoracic scoliosis surgery for AIS with intraoperative CT navigation could significantly decrease the number of CT scans and blood loss while maintaining a comparable PS perforation rate to RF placement at the distal end of the planned PS insertion range.