Comparative Analysis of Cancellous Bone Mineral Density in Vertebral Bodies and Pedicle Screw Trajectories using Quantitative Computed Tomography
Objective The primary objective of this study is to assess the feasibility and accuracy of quantitative computed tomography(QCT)in analyzing the cancellous bone mineral density(BMD)of vertebral bodies and pedicle screw trajectories.Additionally,the study aims to investigate the presence and extent of any significant differences in BMD between these two anatomical regions.Methods This retrospective study was conducted under the approval of our institutional review board,with the requirement for informed consent waived due to the non-interventional nature of the analysis.From October 2021 to April 2022,data from 99 consecutive participants[48 males and 51 females,aged 20 to 80 years,with a mean age of(50.90±15.80)years]who underwent lumbar QCT examinations at The Affiliated Ben Q Hospital of Nanjing Medical University were analyzed.For each participant,the pedicle screw trajectory(designated as G)was segmented into two parts:The intrapedicular segment(R1)and the intracorporal segment(R2).Using a commercial QCT BMD analysis system,BMD measurements were obtained from the trabecular bone of lumbar vertebrae 2,3,and 4,specifically focusing on R1,R2,and the vertebral body(R3).Statistical analysis was performed using one-way ANOVA to evaluate and compare the differences in BMD among R1,R2,and R3.To further examine the difference between the BMD of the entire pedicle screw trajectory(G)and that of the vertebral body(R3),a paired t-test was conducted.A statistical significance level of P＜0.01 was established for all tests employed in this study.Results The analysis revealed significant differences in BMD between the segments of the pedicle screw trajectory.Specifically,the mean BMD of the intrapedicular segment(R1)was(173.66±71.84)mg/cm3,which was significantly higher than that of the intracorporal segment(R2)at(113.81±48.83)mg/cm3(P＜0.01).Comparison of the mean BMD between R1 and the vertebral body[R3,(118.94±47.24)mg/cm3]also showed a significant difference(P＜0.01),whereas the difference between R2 and R3 did not reach statistical significance(P＞0.01).Additionally,no significant differences were observed in BMD measurements between left and right sides[left,(143.14±70.06)mg/cm3;right,(144.33±66.56)mg/cm3;P＞0.01]or among different lumbar levels[L2,(141.25±50.32)mg/cm3;L3,(138.31±56.85)mg/cm3;L4,(151.64±58.62)mg/cm3;P＞0.01].Similarly,the average BMD of R3 did not significantly vary among lumbar levels 2,3,and 4[L2,(124.28±47.04)mg/cm3;L3,(115.36±46.34)mg/cm3;L4,(117.19±48.33)mg/cm3;P＞0.01].Notably,the global BMD of the pedicle screw trajectory[G,(143.73±55.49)mg/cm3]was significantly higher than that of the vertebral body(R3)(P＜0.01).ConclusionQuantitative computed tomography(QCT)provides a reliable method for assessing bone mineral density(BMD)in both vertebral bodies and pedicle screw trajectories.Our findings demonstrate that the BMD of the global pedicle screw trajectory is significantly higher than that of the corresponding segmental vertebral body,highlighting the importance of considering these differences in pre-operative planning and assessment of bone quality for spinal fixation procedures.
quantitative computed tomographybone mineral densitypediclescrew trajectory
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