Department of Orthopaedics and Traumatology, Medical University of Innsbruck, Austria.
Division of Clinical and Functional Anatomy, Department of Anatomy, Histology and Embryology, Medical University of Innsbruck, Innsbruck, Austria.
Clin Biomech (Bristol). 2023 Jun;106:106010. doi: 10.1016/j.clinbiomech.2023.106010. Epub 2023 May 24.
To evaluate the effects of different pedicle screw augmentation strategies on screw loosening and adjacent segment collapse at the proximal end of long-segment instrumentation.
Eighteen osteoporotic (9 male, 9 female donors; mean age: 74.7 ± 10.9 [SD] years) thoracolumbar multi-segmental motion segments (Th11 - L1) were assigned as follows: control, one-level augmented screws (marginally), and two-level augmented screws (fully augmented) groups (3 × 6). Pedicle screw placement was performed in Th12 and L1. Cyclic loading in flexion started with 100-500 N (4 Hz) and was increased by 5 N every 500 cycles. Standardized lateral fluoroscopy images with 7.5 Nm loading were obtained periodically during loading. The global alignment angle was measured to evaluate the overall alignment and proximal junctional kyphosis. The intra-instrumental angle was used to evaluate screw fixation.
Considering screw fixation as a failure criterion, the failure loads of the control (683 N), and marginally (858 N) and fully augmented (1050 N) constructs were significantly different (ANOVA p = 0.032).Taking the overall specimen alignment as failure criteria, failure loads of the three groups (control 933 ± 271.4 N, marginally 858 N ± 196 N, and full 933 ± 246.3 N were in the same range and did not show any significance (p = 0.825).
Global failure loads were comparable among the three groups and unchanged with augmentation because the adjacent segment and not the instrumentation failed first. Augmentation of all screws showed significant improved in screw anchorage.
评估不同椎弓根螺钉增强策略对长节段器械近端螺钉松动和相邻节段塌陷的影响。
将 18 例骨质疏松（9 男，9 女供体；平均年龄：74.7±10.9[SD]岁）胸腰椎多节段运动节段（Th11-L1）分为以下三组：对照组、单节段增强螺钉（边缘增强）和双节段增强螺钉（完全增强）组（3×6）。在 Th12 和 L1 进行椎弓根螺钉置入。在弯曲时，用 100-500N（4Hz）开始循环加载，每 500 次循环增加 5N。在加载过程中定期进行带有 7.5Nm 加载的标准侧位荧光透视图像。测量整体对线角度以评估整体对线和近端交界后凸角。使用内置仪器角度评估螺钉固定。
如果将螺钉固定作为失效标准，对照组（683N）、边缘增强组（858N）和完全增强组（1050N）的失效载荷有显著差异（ANOVA p=0.032）。如果以整体标本对线作为失效标准，三组的失效载荷（对照组 933±271.4N、边缘增强组 858N±196N、完全增强组 933±246.3N）在同一范围内，没有显著差异（p=0.825）。
三组的整体失效载荷相当，由于首先是相邻节段而不是器械失效，因此增强后没有改变。所有螺钉的增强均显著提高了螺钉的锚固力。
