Castro Javier, Wadhwa Harsh, Okoli Olivia, Chan Calvin, Ahmad Somayeh H, Karnowska Anna, Hu Serena, Koltsov Jayme, Bruckman Karl, Mok James
Department of Orthopaedic Surgery, Stanford University Medical Center, Stanford, CA.
School of Medicine, Stanford University, Stanford, CA.
Spine (Phila Pa 1976). 2025 Jul 24. doi: 10.1097/BRS.0000000000005461.
Biomechanical/basic science.
To evaluate efficacy of dental cement augmentation of lateral mass screws in the cervical spine.
Premature loosening and fixation failure is a known problem of screw fixation of the spine, especially in cases of poor bone quality. Cement augmentation of screws with PMMA has limited utility in the cervical spine due to the small size of the bone and high risk of extravasation. Augmentation with dental cement may present a viable solution for posterior cervical spinal screw fixation.
15 cadaveric cervical vertebra were prepared. Lateral mass screw fixation (3.5×12 mm) was performed bilaterally with standard freehand technique by an attending spine surgeon. For augmented screws, dental composite was applied into the screw hole before placement of the screw. 9 vertebrae were used for pull-out testing. Screws were attached to a material testing machine and axially loaded until failure. In the remaining 6 vertebrae, peak torque required to remove the screws from bone was measured via a digital torque driver. A t-test was used to analyze the results between the augmented and non-augmented groups with significance set to P<0.05.
Augmented lateral mass screws exhibited significantly higher pullout strength (263.8±79.4N) compared to non-augmented screws (127.7±21.2N). (P=0.0005) There was no significant difference in the mean torque required for screw removal between the augmented (4.20±2.83 lb-in) and non-augmented groups (4.49±2.09 lb-in) (P=0.9). The dental composite was radio-opaque and observable on xray.
Augmentation with dental composite enhanced pullout strength without altering removal torque of cervical lateral mass screws in human bone. Dental cement augmentation of lateral mass screws during subaxial cervical spine fusion may be a safe and effective method of improving fixation strength without affecting ease of revision.
生物力学/基础科学。
评估牙骨质增强颈椎侧块螺钉的疗效。
过早松动和固定失败是脊柱螺钉固定已知的问题，尤其是在骨质较差的情况下。由于骨尺寸小和渗漏风险高，聚甲基丙烯酸甲酯（PMMA）螺钉增强在颈椎中的应用有限。牙骨质增强可能是颈椎后路螺钉固定的一个可行解决方案。
准备15个尸体颈椎。由一位脊柱外科主治医师采用标准徒手技术双侧进行侧块螺钉固定（3.5×12毫米）。对于增强螺钉，在放置螺钉前将牙科复合材料应用于螺钉孔。9个椎体用于拔出测试。将螺钉连接到材料试验机上并轴向加载直至失效。在其余6个椎体中，通过数字扭矩驱动器测量从骨中取出螺钉所需的峰值扭矩。采用t检验分析增强组和未增强组之间的结果，显著性设定为P<0.05。
与未增强螺钉（127.7±21.2N）相比，增强侧块螺钉表现出显著更高的拔出强度（263.8±79.4N）。（P = 0.0005）增强组（4.20±2.83磅英寸）和未增强组（4.49±2.09磅英寸）之间取出螺钉所需的平均扭矩无显著差异（P = 0.9）。牙科复合材料是不透射线的，在x光片上可观察到。
牙科复合材料增强提高了拔出强度，而不改变人骨中颈椎侧块螺钉的取出扭矩。在颈椎下颈椎融合术中，牙骨质增强侧块螺钉可能是一种安全有效的提高固定强度且不影响翻修便利性的方法。
