先天性C2/3融合患者行后路椎弓根螺钉固定时融合椎置钉位置的选择

Choice of pedicle screw fixation in patient with congenital fusion of cervical 2/3 vertebra

目的：探讨伴C2／3先天性融合的上颈椎疾病患并采用后路椎弓根螺钉同定时融合椎置钉位置的选择。方法：2007年1月至2011年6月，我科收治上颈椎疾病合许C2／3先天性融合畸形患者28例，男16例，女12例，年龄24～64岁。甲均46．5岁。颅底凹陷合并寰愀椰：脱化22例，脚状突骨折6例。均采用后路枕-颈或寰-枢椎内同定术治疗．其中1例因全麻下不能复位结合一期经口腔前路松解。术前采用三维CT最建测量C2、C3椎弓根高度及宽度，将椎弓根直径小于4．0ram定义为椎弓根细小，不适合镫入椎弓根螺钉；告C2、C3椎弓根钉道卣径均大于4ram．根据术中情况酌情选择存C2或C3骰钉：符其中一个椎弓根直径小于4mm，则在另一椎体固定；若两个椎体同侧柞弓根直径均小于4mm,则将固定肖段延K至C4。随访观察螺钉㈨定情况。结果：28例患者中，其中3例（10．7％）为同侧细小，术中融合椎椎弓根螺钉定于C27例，C316例，置于一侧C2和另一侧C32例，C2、C3同侧椎弓根细小不能置钉固定于C43例、术后所何患抒均仃CT复查，16枚C2水弓根螺钉内壁穿破l枚，外壁穿破2枚．占19％：34枚C3螺钉内壁穿破2枚．外壁穿破3枚，占14．7％，均无椎动脉及脊髓神经损伤。24例患者随访1．5～5年，平均3．2年，无内吲定断裂松动及似火节形成。结论：C2／3先天性融合患背C3椎弓根细小的发生率碌著低于C2．大部分C2／3融合椎后路椎弓根螺钉可置于C2或C3，术前行三维CT再建可为髓钉位置选择提供依据．

Objectives： To evaluate the choice of optimal fixation segment and feasibility of posterior pedicle screw instrumentation in C2/3 congenital fusion. Methods： from January 2007 to June 2011, 28 patients with upper cervieal diseases and congenital cervical 2/3 tilsion （C2/3 block veriehrae）, including 16 males and 12 females, were managed in our hospital, h included 22 cases of hasilar impression and atlantoaxial dislocation and 6 cases of odontoid fractures. The mean age was 46.5（24-64） years. Posterior fixation and fusion surgery were performed to manage these patients. Anterior Irans-oral release procedure was added on 1 case. the filsed segments of C2 and C3 were evaluated with 3-dimensional CT to analyze the pedicle screw trajectories of C2 and C3. The widths and heights of the pars iulerarlicularis（ur pedicle） of C2 and pedicle of C3 were measured and the Irajectory was defined as narrowing when the value was less than 4ram. The pedicle screws ere placed in the C2 or C3 according to the measurement of tra.jeelories and should be avoided to place in the naxTowing trajectories. Specifically, if the both C2 and C3 pedieles were narrow, the pedicle screws were placed in the C4 segment instead. The patients were fi）llowed up in terms of fixation status postoperatively. Results： Nan＇uwing of C2 pedicle was identified in 15 pafients（53,6%）, while it was identified in 6 patients （21.4%） in C3, including 3 cases（10.7%） with both-level narrowing at the same side. During the operation, 7palienis were managed with pediele screws fixed in C2, 16 in C3 and 3 in C4. In 2 patients, screws were placed in C2 on one side and in C3 on the other. Posloperative CT analysis showed 1 internal breach and 2 external breaehes of screw trajectories in the 16 C2 pediele screws, and 2 internal breaches and 3 external breaches in the 34 C3 screws. No ialrogcnic injiury of vertebral artery or spinal cord developed. 24 patients were followed up for a mean of 3.2（1.5 to 5） years and no breakage or loosening of fixation occurred. Conclusions： The incidence of pediele narrowing in C2 is significantly higher Ihan that in C3. C3 pediele screw fixation is feasible in most patients with C2/3 congenital fusion and it can serve as a reliable substitute in those patients wilh hartruing C2 pedicles.