Reducing the radiation dose of intraoperative cone beam computed tomography (CBCT) during posterior spinal fusion (PSF) for paediatric scoliosis does not lead to an increased rate of pedicle screw violation, new research has shown.
The retrospective observational study, the findings of which were published in the journal Spine by Hiroki Oba (Shinshu University School of Medicine, Nagano, Japan) et al, sought to determine the effect of reducing the radiation dose of intraoperative CBCT during PSF for paediatric scoliosis on the rate of pedicle screw violation.
According to the research team, the study results indicate however that “extra care is warranted for vertebrae close to the upper instrumented vertebra (UIV) and patients of shorter stature”.
In total, 855 pedicle screws inserted into 58 paediatric scoliosis patients (11 male and 47 female, mean age 16.6 years) who underwent PSF using CBCT were evaluated. A radiation dose of 1/3 or 1/5 of the normal dose was defined as a low dose.
After pedicle screw insertion, intraoperative CBCT images were reviewed to assess the degree of pedicle perforation. G2–3 (i.e., perforations of 4mm or more) was defined as a violation. The pedicle screw violation rate was compared between the groups, and factors associated with violations were examined.
In total, 567 and 288 screws were inserted in the normal dose group and low dose group, respectively. The pedicle screw violation rate was comparable, at 1.8% in the no dose group and 1.7% in the low dose group.
Multiple logistic regression analysis showed that distance from the UIV was an independently associated factor of pedicle screw violation (+1 vertebra, operation room 0.73; p=0.038). In addition, the mean height of patients with pedicle screw violations (148.8 ± 3.6cm) was significantly shorter than that of patients without violations (157.9 ± 1.2cm; p=0.034).