Measurement of vertebrae rotational degree with the entry point of pedicle screws: Bi-directional verification by experimental and clinical results / 中国组织工程研究

ABSTRACT

BACKGROUND: Vertebrae axial rotation is a basic deformity of scoliosis, the rotational degree of which is hard to measure due to the field limitation of posterior spinal instrumentation. Currently, vertebrae rotational degree is measured according to preoperative X-ray film or CT, while no reports concerning measuring vertebrae rotational degree during operation. OBJECTIVE: To explore the feasibility of measurement of vertebrae rotational degree with the entry point of pedicle screws.METHODS: Design of the path of pedicle screws on CT scans before surgery, a line bisection and perpendicular to another connecting bilateral entry point of pedicle screws, and the angle of vertebral rotation (EPPsag) was taken as the angle between this line and the saggital plane. The difference among vertebrae rotational degrees measured by conimeter, Ho's method and EPPsag was compared by Wilcoxon signed rank test. The intra-observer and inter-observer difference was analyzed with One-WayANOVA. Conimeter was used to measure vertebrae rotational degree of each vertebra in 9 lumbar specimens, and the results was compared to EPPsag.RESULTS AND CONCLUSION: There was no significant difference among EPPsag, actual rotational degree and measuring results of Ho's method (P>0.05). The One-Way ANOVA showed that the differences between intra-observer analysis and inter-observer analysis (P>0.05). The results demonstrated that EPPsag can exhibit vertebrae rotational degree accurately and repeatability. This anger can be obtained accurately with the instrument if the vertebrae rotational degree not exceeding 30°.