Spine Center and Department of Orthopaedic Surgery, Seoul National University College of Medicine and Seoul National University Bundang Hospital, Sungnam, Korea.
Spine (Phila Pa 1976). 2013 Jun 1;38(13):1146-53. doi: 10.1097/BRS.0b013e31828aadf5.
Evaluation using 3-dimensional screw trajectory software and computed tomographic scans.
To investigate the anatomic feasibility of laminar screw placement in the upper thoracic spine compared with pedicle screw placement.
Although laminar screws have been suggested as an alternative to pedicle screws in the upper thoracic spine, previous anatomic feasibility studies have some limitations.
Four types of screws were simulated from T1 to T6: unilaminar screw (US), superior bilaminar screw (SBS), inferior bilaminar screw (IBS), and pedicle screw (PS). Maximum allowable screw dimensions and the success rates of 4.5-mm screw placement were compared for each level. Laminar screw dimensions with more than 90% success rate at each level were determined for reference.
Computed tomographic scans of 132 patients were analyzed. Laminar screw diameters gradually increased from T1 (4.4-5.4 mm, for each type) to T6 (4.8-6.7 mm), whereas PS diameter steeply declined from T1 (5.9 mm) to T4 (3.4 mm) and then leveled off. At T1, PS had greater success rate of 4.5-mm screw placement than laminar screws (US > IBS > SBS); at T2, US had greater success rate than IBS, followed by PS and SBS; and at T3 to T6, laminar screws (US > IBS > SBS) had greater success rate than PS in all comparisons. Except for SBS at T1, laminar screw diameters with more than 90% success rates were between 3.5 and 5.0 mm.
In view of their anatomic feasibility, laminar screws can be a viable alternative to PSs in the upper thoracic spine. Particularly at T3 to T6 where the pedicle width is inherently small, the success rates of laminar screw placement were significantly and consistently higher than those of PS placement. The comparable success rates of laminar screws using commercially available screw sizes further emphasize their potential clinical use.
使用三维螺钉轨迹软件和计算机断层扫描进行评估。
研究与椎弓根螺钉相比，在上胸椎中使用椎板螺钉进行解剖学可行性。
尽管已经提出在上胸椎中使用椎板螺钉作为椎弓根螺钉的替代物，但以前的解剖学可行性研究存在一些局限性。
从 T1 到 T6 模拟了四种类型的螺钉：单椎板螺钉（US）、上双椎板螺钉（SBS）、下双椎板螺钉（IBS）和椎弓根螺钉（PS）。比较了每个节段的最大允许螺钉尺寸和 4.5 毫米螺钉放置的成功率。确定了每个节段成功率超过 90%的椎板螺钉尺寸作为参考。
分析了 132 名患者的计算机断层扫描。椎板螺钉直径从 T1（每种类型为 4.4-5.4 毫米）逐渐增加到 T6（4.8-6.7 毫米），而 PS 直径从 T1（5.9 毫米）急剧下降到 T4（3.4 毫米），然后趋于平稳。在 T1，PS 的 4.5 毫米螺钉放置成功率高于椎板螺钉（US>IBS>SBS）；在 T2，US 的成功率高于 IBS，其次是 PS 和 SBS；在 T3 到 T6，除了 T1 的 SBS，椎板螺钉（US>IBS>SBS）在所有比较中的成功率均高于 PS。除了 T1 的 SBS，成功率超过 90%的椎板螺钉直径在 3.5 到 5.0 毫米之间。
鉴于其解剖学可行性，椎板螺钉在上胸椎中可以作为椎弓根螺钉的可行替代物。特别是在椎弓根宽度本来就小的 T3 到 T6，椎板螺钉放置的成功率明显且始终高于椎弓根螺钉放置的成功率。使用市售螺钉尺寸的椎板螺钉具有可比的成功率进一步强调了它们的潜在临床应用。
