寰椎椎弓根显露置钉技术的影像学测量研究

目的 :利用CT三维重建对椎动脉沟后弓高度4 mm的寰椎进行置钉通道相关参数测量,探讨椎弓根显露置钉技术的意义。方法:回顾性分析2015年4月至2015年6月行颈椎CT三维重建检查且排除上颈椎畸形、手术的患者90例,其中单侧或双侧椎动脉沟后弓高度4 mm的51例,共84侧。利用其图像数据行寰椎三维数字化重建,并分别测量置钉通道相关数据。结果:51例患者中,椎动脉沟处后弓最低高度为(3.28±0.51)mm,侧块高度、宽度、与后弓移行处高度均可容纳3.5 mm直径螺钉置入。0°~15°(0°、5°、10°、15°)理想椎弓根螺钉钉道长度依次为(27.36±1.81)、(27.01±1.68)、(27.07±1.75)、(27.48±1.72)mm,椎弓根显露置钉技术钉道长度依次为(23.44±1.79)、(23.87±1.84)、(24.58±1.89)、(25.56±2.01)mm,侧块螺钉钉道长度为(20.78±2.05)mm。螺钉通道5个截面的CT值均值分别为椎弓根螺钉(701.89±141.48)HU、侧块螺钉(599.11±137.33)HU。0°~15°理想椎弓根螺钉通道长度之间差异无统计学意义(P0.05),0°~15°椎弓根显露置钉法钉道长度随内倾角增加而增长(P0.05),且均比侧块螺钉钉道长(P0.05),椎弓根螺钉通道穿过骨质CT值均值高于侧块螺钉通道(P0.01)。结论:利用椎弓根显露置钉技术可完成椎动脉沟处后弓高度4 mm的寰椎置钉,且钉道长度损失不多,穿行骨量较大,预期把持力良好。

Pedicle exposure technique for atlas screw fixation:a radiological research

Objective:To investigate the meaning of pedicle exposure technique for screw fixation on atlas with the vertebral groove height less than 4 mm by using reconstructive computed tomography.Methods:From April 2015 to June 2015,84 pedicles of 51 patients with groove heights less than 4 mm were studied by digital reconstruction respectively. Parameters of atlas pedicle screw fixation were measured.Results:Among the 51 cases,the vertebral groove height was (3.28±0.51) mm. Lateral mass heights,lateral mass widths and the transition area heights between lateral mass and posterior arch were fit for 3.5 mm screw implanting. Ideal pedicle screw trajectory lengths from 0° to 15° (0°,5°,10°,15°) were (27.36±1.81),(27.01±1.68),(27.07±1.75),(27.48±1.72) mm,exposed trajectory lengths from 0° to 15°(0°,5°,10°,15°) were(23.44±1.79),(23.87±1.84),(24.58±1.89),(25.56±2.01) mm,trajectory length of lateral mass was (20.78±2.05) mm. The mean CT values on 5 sections through pedicle trajectory and lateral mass trajectory were (701.89±141.48) HU and (599.11±137.33) HU,respectively. There were no significant differences between ideal pedicle trajectory lengths from 0° to 15°(P>0.05). Exposed trajectory lengths was significantly increased accompanying with medial angles increasing (P<0.05),and was longer than trajectory lengths of lateral mass (P<0.05). CT value of pedicle screws was higher than CT value of lateral mass screws significantly (P<0.01).Conclusion:Screws can be implanted in atlas with vertebral groove height less than 4 mm by using pedicle exposure technique. Few trajectory lengths will be sacrificed with favorable pull-out strength due to adequate bone mass purchased.