Department of Orthopaedic Surgery, Gyeongsang National University School of Medicine and Gyeongsang National University Changwon Hospital, Changwon, Republic of Korea.
Department of Orthopaedic Surgery, Kyungpook National University Hospital, 130 Dongduk-ro, Jung-gu, Daegu, Republic of Korea.
Spine J. 2021 Sep;21(9):1580-1586. doi: 10.1016/j.spinee.2021.04.010. Epub 2021 Apr 17.
To evaluate the differences in the pullout strength and displacement of pedicle screws in cadaveric thoracolumbar vertebrae with or without artificial demineralization.
Five human lumbar and five thoracic vertebrae from one cadaver were divided into two hemivertebrae. The left-side specimens were included in the simulated osteopenic model group and the right-side bones in a control group. In the model group, we immersed each specimen in HCl (1 N) solution for 40 minutes. We measured bone mineral density (BMD) using dual-energy X-ray absorptiometry and quantitative computerized tomography. We inserted polyaxial pedicle screws into the 20 pedicles of the cadaveric lumbar and thoracic spine after measuring the BMD of the 2 hemivertebrae of each specimen. We measured the pullout strength and displacement of the screws before failure in each specimen using an Instron system.
The average pullout strength of the simulated osteopenic model group was 76% that of the control group. In the control and model groups, the pullout strength was 1678.87±358.96 N and 1283.83±341.97 N, respectively, and the displacement was 2.07±0.34 mm and 2.65±0.50 mm, respectively (p<.05). We detected positive correlations between pullout strength and BMD in the control group and observed a negative correlation between displacement and BMD in the model group.
By providing an anatomically symmetric counterpart, the human cadaveric model with or without demineralization can be used as a test bed for pullout tests of the spine. In the simulated osteopenic model group, pullout strength was significantly decreased compared with the untreated control group.
Decreased bone mineral density may significantly reduce the pullout strength of a pedicle screw, even though the range is osteopenic rather than osoteoporotic.
评估去矿化前后胸腰椎尸体标本椎弓根螺钉拔出强度和位移的差异。
从一具尸体的 5 个腰椎和 5 个胸椎中，将每个椎体分为左右两半。左侧标本纳入模拟骨质疏松模型组，右侧标本纳入对照组。模型组将每个标本的骨组织浸泡在 1N 的 HCl 溶液中 40 分钟。测量每对半椎体的骨密度（BMD），并用双能 X 射线吸收法和定量计算机断层扫描法测量。在每对半椎体测量 BMD 后，将多轴椎弓根螺钉插入 20 个腰椎和胸椎椎弓根。使用 Instron 系统测量每个标本螺钉拔出前的拔出强度和位移。
模拟骨质疏松模型组的平均拔出强度为对照组的 76%。在对照组和模型组中，拔出强度分别为 1678.87±358.96 N 和 1283.83±341.97 N，位移分别为 2.07±0.34 mm 和 2.65±0.50 mm（p<.05）。我们在对照组中检测到拔出强度与 BMD 之间存在正相关，在模型组中观察到位移与 BMD 之间存在负相关。
通过提供解剖对称的对照，去矿化和未去矿化的人体尸体模型可作为脊柱拔出试验的测试平台。在模拟骨质疏松模型组中，与未处理的对照组相比，拔出强度显著降低。
骨密度降低可能会显著降低椎弓根螺钉的拔出强度，即使范围是骨质疏松而不是骨质疏松症。
