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

中文关键词:  C2/3先天性融合  椎弓根螺钉  三维CT

英文关键词:C2/3 congenital fusion  Pedicle Screw  3-dimensional CT

中文摘要:

  【摘要】 目的：探讨伴C2/3先天性融合的上颈椎疾病患者采用后路椎弓根螺钉固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并C2/3先天性融合畸形患者28例，男16例，女12例，年龄24~64岁，平均46.5岁。颅底凹陷合并寰枢椎脱位22例，齿状突骨折6例。均采用后路枕-颈或寰-枢椎内固定术治疗，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重建测量C2、C3椎弓根高度及宽度，将椎弓根直径小于4.0mm定义为椎弓根细小，不适合置入椎弓根螺钉；若C2、C3椎弓根钉道直径均大于4mm，根据术中情况酌情选择在C2或C3置钉；若其中一个椎弓根直径小于4mm，则在另一椎体固定；若两个椎体同侧椎弓根直径均小于4mm，则将固定节段延长至C4。随访观察螺钉固定情况。结果：28例患者中，C2椎弓根细小15例（53.6%），C3椎弓根细小6例（21.4%），C2及C3椎弓根均细小5例（17.9%），其中3例（10.7%）为同侧细小。术中融合椎椎弓根螺钉固定于C2 7例，C3 16例，置于一侧C2和另一侧C3 2例，因C2、C3同侧椎弓根细小不能置钉固定于C4 3例。术后所有患者均行CT复查，16枚C2椎弓根螺钉内壁穿破1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，无内固定断裂松动及假关节形成。结论：C2/3先天性融合患者C3椎弓根细小的发生率显著低于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重建可为置钉位置选择提供依据。

英文摘要:

  【Abstract】 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 cervical diseases and congenital cervical 2/3 fusion(C2/3 block vertebrae), including 16 males and 12 females, were managed in our hospital. It included 22 cases of basilar 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 trans-oral release procedure was added on 1 case. The fused 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 interarticularis(or pedicle) of C2 and pedicle of C3 were measured and the trajectory was defined as narrowing when the value was less than 4mm. The pedicle screws were placed in the C2 or C3 according to the measurement of trajectories and should be avoided to place in the narrowing trajectories. Specifically, if the both C2 and C3 pedicles were narrow, the pedicle screws were placed in the C4 segment instead. The patients were followed up in terms of fixation status postoperatively. Results: Narrowing of C2 pedicle was identified in 15 patients(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, 7 patients were managed with pedicle 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. Postoperative CT analysis showed 1 internal breach and 2 external breaches of screw trajectories in the 16 C2 pedicle screws, and 2 internal breaches and 3 external breaches in the 34 C3 screws. No iatrogenic injury 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 pedicle narrowing in C2 is significantly higher than that in C3. C3 pedicle screw fixation is feasible in most patients with C2/3 congenital fusion and it can serve as a reliable substitute in those patients with narrowing C2 pedicles.