• Yusuke Tanikawa, Hiroki Oba, Masahiro Fujii, Shota Ikegami, Masashi Uehara, Tetsuhiko Mimura, Jun Miyagawa, Terue Hatakenaka, Shugo Kuraishi, Takashi Takizawa, Ryo Munakata, Takayuki Kamanaka, Yoshinari Miyaoka, Koseki Michihiko, and Jun Takahashi.
• Department of Orthopaedic Surgery, Shinshu University School of Medicine, Matsumoto, Nagano, Japan.
• Spine. 2022 Jun 15; 47 (12): E507-E513.

Study DesignRetrospective observational study.ObjectiveThis study aimed to determine the effect of reducing the radiation dose of intraoperative cone beam computed tomography (CBCT) during posterior spinal fusion (PSF) for pediatric scoliosis on the rate of pedicle screw (PS) violation.Summary Of Background DataIntraoperative CBCT for pediatric scoliosis improves the accuracy of PS insertion in PSF. However, few reports have addressed the PS perforation rate from reduced radiation doses in hybrid navigation.MethodsWe evaluated 855 PSs inserted into 58 pediatric scoliosis patients (11 male and 47 female, mean age: 16.6 yr) who underwent PSF using CBCT. A radiation dose of 1/3 or 1/5 of the normal dose (ND) was defined as a low dose (LD). After PS insertion, intraoperative CBCT images were reviewed to assess the degree of PS perforation. G2-3 (i.e., perforations of 4 mm or more) was defined as a violation. The PS violation rate was compared between the groups, and factors associated with violations were examined.ResultsA total of 567 and 288 screws were inserted in the ND group and LD group, respectively. The PS violation rate was comparable at 1.8% in the ND group and 1.7% in the LD group. Multiple logistic regression analysis showed that distance from the upper instrumented vertebra (UIV) was an independently associated factor of PS violation (+1 vertebra, operation room 0.73, P   =  0.038). In addition, the mean height of patients with PS violations (148.8 ± 3.6 cm) was significantly shorter than that of patients without violations (157.9 ± 1.2 cm) ( P  = 0.034).ConclusionThere was no increase in PS violation rate with lower doses of radiation for intraoperative navigation CBCT. Extra care is warranted for vertebrae close to the UIV and patients of shorter stature.Level of Evidence: 3.Copyright © 2022 Wolters Kluwer Health, Inc. All rights reserved.

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