Mai Harry T, Mitchell Sean M, Hashmi Sohaib Z, Jenkins Tyler J, Patel Alpesh A, Hsu Wellington K
Department of Orthopaedic Surgery, Northwestern University Feinberg School of Medicine, Chicago, IL, USA.
Department of Orthopaedic Surgery, Northwestern University Feinberg School of Medicine, Chicago, IL, USA.
Spine J. 2016 Jul;16(7):835-41. doi: 10.1016/j.spinee.2015.11.034. Epub 2015 Dec 2.
The use of a novel lumbar pedicle cortical bone trajectory (CBT) screw has recently gained popularity, allowing for a minimally invasive approach and potentially improved screw purchase. However, to date, no studies have identified the ideal patient population to utilize this technology.
This study reports the bone mineral density (BMD) using Hounsfield units (HUs) along a CBT screw pathway. Patients with a greater difference in density of bone in the lumbar vertebrae between the fixation points of the CBT and traditional pedicle screw may be optimal candidates to realize the advantages of this technique.
STUDY DESIGN/SETTING: A cross-sectional observational anatomic study was carried out.
The sample comprised 180 randomly selected patients with lumbar computed tomography imaging from L1 to L5 spinal levels.
This study used computed tomography image-derived HUs as a metric for BMD.
A total of 180 patients without previous lumbar surgery with computed tomography imaging of the lumbar spine met the inclusion criteria. Patients were chosen randomly from an institutional database based on age (evenly distributed by decade of life) and gender. Hounsfield units were measured at the expected end fixation point for both a cortical (superior/posterior portion of the vertebral body) and traditional pedicle trajectory (mid-vertebral body).
Hounsfield unit values measured at the end fixation point for the CBT screw were significantly greater than that of the traditional pedicle screw in all age groups. The relative difference in HU values significantly increased with each decade of age (p<.001) and caudal lumbar level (p<.001). In the osteoporotic group, as determined by well-established HU values, there was a significantly greater difference in the BMD of the CBT fixation point compared with the traditional trajectory (p=.048-<.001).
Bone mineral density as measured by HU values for the fixation point of the CBT screw is significantly greater than that of the traditional pedicle screw. This difference is even more pronounced when comparing osteoporotic and elderly patients to the general population. The data in this study suggest that the potential advantages from the CBT screw such as screw purchase may increase linearly with age and in osteoporotic patients.
一种新型腰椎椎弓根皮质骨轨迹（CBT）螺钉的应用近来颇受关注，它能实现微创入路并可能增强螺钉把持力。然而，迄今为止，尚无研究确定使用该技术的理想患者群体。
本研究报告沿CBT螺钉路径使用亨氏单位（HU）测量的骨密度（BMD）。在CBT螺钉与传统椎弓根螺钉的固定点之间腰椎椎体骨密度差异更大的患者，可能是实现该技术优势的最佳候选者。
研究设计/地点：进行了一项横断面观察性解剖学研究。
样本包括180例随机选取的L1至L5腰椎水平的计算机断层扫描成像患者。
本研究使用计算机断层扫描图像得出的HU作为骨密度指标。
共有180例未曾接受过腰椎手术且有腰椎计算机断层扫描成像的患者符合纳入标准。患者根据年龄（按年龄段均匀分布）和性别从机构数据库中随机选取。在预期的终末固定点，对皮质骨（椎体上/后部）和传统椎弓根轨迹（椎体中部）测量亨氏单位。
在所有年龄组中，CBT螺钉终末固定点处测量的亨氏单位值均显著高于传统椎弓根螺钉。HU值的相对差异随年龄每增长十岁（p<.001）和腰椎尾端节段（p<.001）而显著增加。在根据既定HU值确定的骨质疏松组中，CBT固定点的骨密度与传统轨迹相比差异显著更大（p=.048 - <.001）。
通过HU值测量的CBT螺钉固定点的骨密度显著高于传统椎弓根螺钉。将骨质疏松患者和老年患者与普通人群相比时，这种差异更为明显。本研究数据表明，CBT螺钉的潜在优势如螺钉把持力可能随年龄增长和在骨质疏松患者中呈线性增加。
