基于钉道周围骨质CT值分析皮质骨通道螺钉在骨质疏松性胸腰椎内固定应用中的可行性

Feasibility of using cortical bone trajectory screws in osteoporotic thoracolumbar fixation based on evaluation of bone CT values at bone-screw interface

目的通过测量并分析不同骨量患者分别采用传统椎弓根通道(TT)螺钉和皮质骨通道(CBT)螺钉固定钉道周围骨质CT值,探讨CBT螺钉在骨质疏松性胸腰椎内固定应用中的可行性。方法回顾性分析2020年4月至2022年10月温州医科大学附属第二医院因胸椎或腰椎骨折行胸腰段高分辨率CT扫描的患者影像学资料。根据骨密度T值分为骨量正常、骨量减少、骨质疏松3个组,单组各抽取30例共90例数据,其中男36例,女54例。将各组数据导入Mimics18.0中进行骨组织三维重建,在T_(10)至L_(2)各椎体上(非骨折椎体)模拟TT螺钉与CBT螺钉的置入,分割出各模拟螺钉与骨质相交的感兴趣区域(ROI)并测量其CT值,计算各组各椎体不同置钉方式ROI的CT值的相对差异百分比。在T_(10)至L_(2)同一组内比较两种置钉方式间ROI的CT值,在T_(10)至L_(2)同一种置钉方式比较骨量正常组、骨量减少组、骨质疏松组间ROI的CT值,在T_(10)至L_(2)比较骨量减少组和骨质疏松组CBT螺钉ROI的CT值与骨量正常组TT螺钉ROI的CT值,在T_(10)至L_(2)比较骨量正常组、骨量减少组、骨质疏松组间两种置钉方式ROI的CT值相对差异百分比。结果T_(10)至L_(2)无论何种骨量CBT螺钉ROI的CT值均显著大于TT螺钉,T_(10)至L_(2)无论何种置钉方式ROI的CT值:骨质疏松组<骨量减少组<骨量正常组,T_(10)至L_(2)骨量减少组CBT螺钉ROI的CT值均显著高于骨量正常组TT螺钉,以上比较差异均有统计学意义(P<0.001);而骨质疏松组CBT螺钉ROI的CT值与骨量正常组TT螺钉比较差异均无统计学意义(P>0.05)。在T_(10)、T12、L1椎体,骨量减少组与骨质疏松组CBT与TT螺钉ROI的CT值的相对差异百分比均显著高于骨量正常组,差异均有统计学意义(P<0.05),而骨量减少组与骨质疏松组比较差异均无统计学意义(P>0.05)。在T_(11)、L_(2)椎体,3组之间CBT与TT螺钉ROI的CT值的相对差异百分比比较差异均无统计学意义(P>0.05)。结论随着骨量的降低,CBT和TT螺钉的钉道周围骨密度均明显下降。在骨质疏松患者中,CBT螺钉仍能表现出相对TT螺钉更高的钉道密度,能够提供更高的骨-螺钉界面强度。

Objective To evaluate the feasibility of using cortical bone trajectory(CBT)screws in the osteoporotic thoracolumbar fixation by comparing the bone CT values at the bone-screw interface between traditional trajectory(TT)screws and CBT screws in patients with different bone densities.Methods The high-resolution CT imaging data of thoracolumbar segments following thoracic or lumbar spine fractures from April 2020 to October 2022 were collected at The Second Hospital Affiliated to Wenzhou Medical University for retrospective analysis.They were divided into 3 groups:a normal bone mass group,an osteopenia group and an osteoporosis group.From each group 30 cases were chosen(90 cases in total,36 males and 54 females).All the data were imported into Mimics 18.0 for three-dimensional bone reconstruction in which placement of TT and CBT screws was simulated on the vertebrae from T_(10) to L_(2)(non-fractured vertebrae).Regions of interest(ROI)where each simulated screw intersected the bone were segmented to measure their CT bone values.For each vertebra in each group,the relative difference percentage in average CT value of ROI between TT and CBT screws was calculated.The CT values of ROI were compared in the same group between TT and CBT screws from T_(10) to L_(2);the CT values of ROI were compared in the same screws among the 3 groups from T_(10) to L_(2);the CT values of ROI were compared between the CBT screws in the osteopenia and osteoporosis groups and the TT screws in the normal bone mass group;the relative difference percentages in average CT value of ROI between CBT and TT screws were compared between the 3 groups from T_(10) to L_(2).Results The average CT value of ROI for CBT screws was significantly higher than that for TT screws from T_(10) to L_(2) in every group(P<0.001);as for the CT values of ROI for CBT and TT screws from T_(10) to L_(2),the osteoporosis group<the osteopenia group<the normal bone mass group(P<0.001);from T_(10) to L_(2),the CT value of ROI for CBT screws in the osteopenia group was significantly higher than that for TT screws in the normal bone mass group(P<0.001);the CT value of ROI for CBT screws in the osteoporosis group was not significantly different from that for TT screws in the normal bone mass group(P>0.05).At T_(10),T12,and L1,the relative difference percentage in average CT value of ROI between CBT and TT screws was significantly higher in the osteopenia and osteoporosis groups than that in the normal bone mass group(P<0.05),but there was no such a difference between the osteopenia and the osteoporosis groups(P>0.05).At T_(11) and L_(2),there was no significant difference between the 3 groups in the relative difference percentage in average CT value of ROI between CBT and TT screws(P>0.05).Conclusions As bone mass decreases,both CBT and TT screws lead to a significant decrease in the bone density at the bone-screw interface.In patients with osteoporosis,CBT screws can still lead to a higher bone density at the bone-screw interface than TT screws,thus providing a higher strength at the bone-screw interface.