Department of Spinal Surgery, Zhujiang Hospital of Southern Medical University, Guangzhou, China.
Department of Orthopedic, Affiliated Hospital of Jiujiang University, Jiujiang, China.
Orthop Surg. 2024 Nov;16(11):2771-2780. doi: 10.1111/os.14202. Epub 2024 Aug 26.
The cortical bone trajectory (CBT) technology is an effective substitute for traditional pedicle screw (PS) technology. However, there is still controversy about the CBT screw technology placement strategy. The objective of this study was to simulate cortical screw placement with the help of three-dimensional (3D) software, to discuss the differences in screws between genders and vertebral segments, and to explore a safer and more efficient strategy for cortical screw placement.
Mimics Medical software was used to construct a 3D model of the lumbar spine, and the placement of CBT screws was simulated. The volume of each vertebral body from L1 to L5, the pedicle isthmus height (IH), the pedicle isthmus width (IW), and the sagittal vertebral distance (SAVD) were measured. The transverse distance (TD) and the longitudinal distance (LD) between the ideal starting point (SP) and the clinical SP (the intersection Q of the midline of the superior articular process and the horizontal line 1 mm below the transverse process) were measured. The cephalad angle (CA), lateral angle (LA), maximum screw diameter (MSD), maximum screw length (MSL) of each trajectory of the L1 to L5 vertebral bodies, and the percentage of the screw insertion depth (PSID) into the vertebral body were measured. Data were statistically analyzed using Student's t-test, one-way analysis of variance (ANOVA), and Tukey's test.
Vertebral anatomical parameters and CBT screw parameters differed between males and females. Female patients had lower IH, IW, SAVD, CA, LA, MSD, and MSL than males. IH was greatest in L1 (male, 17.81 mm; female, 16.12 mm) and the smallest in L5 (male, 14.11 mm; female, 13.05 mm). IW was smallest in L1 (male, 8.89 mm; female, 7.37 mm) and greatest in L5 (male, 16.59 mm; female, 15.43 mm). The MSD of males was smallest in L1 (6.05 mm) and greatest in L3 (7.06 mm); the MSD of females was smallest in L1 (5.13 mm) and greatest in L4 (6.64 mm). MSL was greatest at L3 (male, 33.63 mm; female, 32.28 mm) and smallest at L5 (male, 31.25 mm; female, 29.97 mm). CA was smallest in L1 (male, 22.80°; female, 21.92°) and greatest in L3 (male, 25.29°; female, 24.33°). LA was smallest in L1 (male 12.37°, female 11.27°) and greatest in L5 (male 13.56°, female 12.96°). Among the males, TD was smallest at L1 (-0.51 mm) and greatest at L5 (1.37 mm), while LD was greatest at L2 (3.46 mm) and smallest at L5 (2.40 mm). In females, TD was greatest at L1 (0.12 mm) and smallest at L3 (-0.51 mm), while LD was greatest at L1 (3.69 mm) and smallest at L5 (2.08 mm). In the overall sample, the incidence of SAVD and PSID gradually increased from L1 to L5.
The optimal screw placement strategy for CBT screws varies significantly according to sex and vertebral body segments, particularly noting the specificity of screw placement at L5. The optimal screw placement strategy should be selected based on the patient's sex and segment characteristics before surgery to maximize the safety and accuracy of CBT screw placement.
皮质骨轨迹（CBT）技术是传统椎弓根螺钉（PS）技术的有效替代方法。然而，关于 CBT 螺钉技术的放置策略仍存在争议。本研究的目的是通过三维（3D）软件模拟皮质螺钉的放置，讨论男女和椎体节段之间螺钉的差异，并探讨更安全、更有效的皮质螺钉放置策略。
使用 Mimics Medical 软件构建腰椎的 3D 模型，并模拟 CBT 螺钉的放置。测量每个椎体从 L1 到 L5 的体积、椎弓根峡部高度（IH）、椎弓根峡部宽度（IW）和矢状椎体距离（SAVD）。测量理想起始点（SP）和临床 SP（上关节突中点与横突下 1mm 水平线的交点 Q）之间的横向距离（TD）和纵向距离（LD）。测量每个 L1 到 L5 椎体的轨迹的头侧角（CA）、外侧角（LA）、最大螺钉直径（MSD）、最大螺钉长度（MSL）以及螺钉插入椎体的深度百分比（PSID）。使用学生 t 检验、单因素方差分析（ANOVA）和 Tukey 检验对数据进行统计分析。
男女患者的椎体解剖参数和 CBT 螺钉参数存在差异。女性患者的 IH、IW、SAVD、CA、LA、MSD 和 MSL 均低于男性。IH 在 L1 最大（男性，17.81mm；女性，16.12mm），在 L5 最小（男性，14.11mm；女性，13.05mm）。IW 在 L1 最小（男性，8.89mm；女性，7.37mm），在 L5 最大（男性，16.59mm；女性，15.43mm）。男性的 MSD 在 L1 最小（6.05mm），在 L3 最大（7.06mm）；女性的 MSD 在 L1 最小（5.13mm），在 L4 最大（6.64mm）。MSL 在 L3 最大（男性，33.63mm；女性，32.28mm），在 L5 最小（男性，31.25mm；女性，29.97mm）。CA 在 L1 最小（男性，22.80°；女性，21.92°），在 L3 最大（男性，25.29°；女性，24.33°）。LA 在 L1 最小（男性 12.37°，女性 11.27°），在 L5 最大（男性 13.56°，女性 12.96°）。在男性中，TD 在 L1 最小（-0.51mm），在 L5 最大（1.37mm），而 LD 在 L2 最大（3.46mm），在 L5 最小（2.40mm）。在女性中，TD 在 L1 最大（0.12mm），在 L3 最小（-0.51mm），而 LD 在 L1 最大（3.69mm），在 L5 最小（2.08mm）。在总样本中，SAVD 和 PSID 从 L1 到 L5 逐渐增加。
CBT 螺钉的最佳放置策略因性别和椎体节段而异，特别是要注意 L5 处螺钉放置的特异性。在手术前应根据患者的性别和节段特征选择最佳的螺钉放置策略，以最大程度地提高 CBT 螺钉放置的安全性和准确性。
