Department of Orthopaedics and Rehabilitation, University of Iowa Hospitals & Clinics, The University of Iowa, Iowa City, IA 52242, USA.
Spine (Phila Pa 1976). 2013 Feb 15;38(4):E199-204. doi: 10.1097/BRS.0b013e31827de094.
Radiographical and biomechanical analyses.
To determine the applicability of C7 laminar screw fixation using radiographical and biomechanical analysis.
The unique anatomy of C7 creates a challenge during instrumentation at the caudal aspect of the cervical spine and cervicothoracic junction. The C7 lateral mass is often smaller, resulting in increased difficulty for pedicle screw placement. The use of crossing laminar screw fixation is common in the upper cervical and thoracic spine; its use at the C7 level, however, has only recently appeared in the literature.
Radiographical: Computed tomographic scans from 72 patients were used to measure laminar thickness, spinolaminar angle, and length (i.e., from the spinolaminar junction to the contralateral lamina-lateral mass junction) for each C7 vertebrae. Biomechanical: The C2 and C7 vertebrae from 13 cadaveric cervical spines were obtained, scanned using pQCT (Stratec Electronics, Pforzheim, Germany) for bone mineral density, and then instrumented in the following manner: (1) bilateral crossing intralaminar screws in C2, (2) bilateral crossing intralaminar screws in C7, and (3) bilateral pedicle screws in each C7 specimen after completion of laminar screw biomechanical testing. Each specimen was cyclically loaded for 5000 cycles after which axial screw pullout tests were performed.
Radiographical: Mean laminar thickness and length were 5.67 ± 1.00 mm and 25.49 ± 2.73 mm, respectively. Biomechanical: The mean load to failure was 610.3 ± 251 N for C7 laminar screws, 666.33 ± 373N for C7 pedicle screws, and 355 ± 250 N for C2 laminar screws. A student t test indicated no statistical difference in pullout strength between C7 laminar and C7 pedicle screws (P = 0.6).
The radiographical anatomy at C7 suggests that intralaminar screws can be placed in the majority of patients. The in vitro biomechanical analysis performed indicates that C7 laminar screws are as strong as C7 pedicle screws and significantly stronger than laminar screws at C2.
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影像学和生物力学分析。
通过影像学和生物力学分析确定 C7 椎板螺钉固定的适用性。
C7 的独特解剖结构在颈椎和颈胸交界处的下部进行器械操作时带来了挑战。C7 侧块通常较小，导致椎弓根螺钉放置的难度增加。交叉椎板螺钉固定在颈椎和胸椎中很常见；然而，其在 C7 水平的应用最近才出现在文献中。
影像学：使用 72 名患者的计算机断层扫描 (CT) 扫描来测量每个 C7 椎骨的椎板厚度、椎板-棘突角和长度（即从椎板-棘突交界处到对侧椎板-侧块交界处）。生物力学：从 13 具颈椎尸体标本中获得 C2 和 C7 椎体，使用 pQCT（德国普福尔茨海姆的 Stratec Electronics）进行骨密度扫描，然后以以下方式进行器械操作：（1）C2 双侧交叉椎板内螺钉，（2）C7 双侧交叉椎板内螺钉，和（3）完成椎板螺钉生物力学测试后，每个 C7 标本的双侧椎弓根螺钉。每个标本在完成 5000 次循环加载后进行轴向螺钉拔出测试。
影像学：平均椎板厚度和长度分别为 5.67 ± 1.00 毫米和 25.49 ± 2.73 毫米。生物力学：C7 椎板螺钉的失效负荷平均值为 610.3 ± 251 N，C7 椎弓根螺钉的失效负荷平均值为 666.33 ± 373N，C2 椎板螺钉的失效负荷平均值为 355 ± 250 N。学生 t 检验表明 C7 椎板螺钉和 C7 椎弓根螺钉的拔出强度无统计学差异（P = 0.6）。
C7 的影像学解剖表明，大多数患者都可以放置椎板内螺钉。进行的体外生物力学分析表明，C7 椎板螺钉与 C7 椎弓根螺钉一样坚固，明显强于 C2 的椎板螺钉。
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Zotero 插件