CT观察Hangman骨折患者C1~C3椎弓根置钉的影响因素

CT analysis of deformity and injury affecting posterior C1 to C3 pedicle screw fixation for Hangman fracture

中文关键词:  Hangman骨折  后路  钉道  椎弓根螺钉  CT

英文关键词:Hangman fracture  Posterior approach  Screw trajectory  Pedicle screw

中文摘要:

  【摘要】 目的：探讨Hangman骨折患者后路C1~C3椎弓根置钉的影响因素。方法：2004年5月~2012年5月我院脊柱外科收治Hangman骨折患者78例，男性67例，女性11例，年龄17~73岁，平均37.7岁，外伤至手术时间3h~18d。合并不完全性颈脊髓损伤20例。按Edward-Levine分型，Ⅰ型11例，Ⅱ型48例，ⅡA型13例，Ⅲ型6例。将C1后弓高度、C2关节突间部和C3椎弓根横径4mm设定为椎弓根置钉的下限，釆用C0~C3 CT薄层扫描及三维重建观察影响后路C1~C3椎弓根置钉的损伤和/或畸形。结果：78例患者中21例（27%）、25处存在C1~C3固定钉道损伤和/或畸形，置钉困难，其中合并C1后弓发育细小和骨折影响置钉6例次，C2关节突间部发育细小、椎动脉高切迹、粉碎骨折块进入横突孔和/或椎管影响置钉10例次，C3椎弓根发育细小、髓腔硬化、椎体和椎弓根骨折影响置钉9例次。采用前路C2~C3固定融合15例，C3椎体次全切C2~C4固定融合2例，保守治疗4例。其余57例（73%）可完成C1~C3椎弓根螺钉固定，其中55例采用后路手术治疗，C1椎弓根置钉5例，C2椎弓根置钉50例，C3椎弓根置钉50例；2例行保守治疗。采用后路手术治疗者49例术后行CT复查，C2钉道外壁穿破2例，内壁穿破1例，关节突间部分离2例；C3钉道外壁和内壁穿破各1例，其余螺钉位置良好，无血管神经损伤发生。结论：C1椎弓根发育细小和骨折，C2关节突间部发育细小、骨折块对横突孔和/或椎管的侵占、椎动脉高切迹，C3椎弓根发育细小、骨折及髓腔硬化等，都会影响Hangman骨折患者后路C1~C3椎弓根置钉，术前应釆用C0~C3 CT薄层扫描及三维重建，以便选用恰当的治疗方法。

英文摘要:

  【Abstract】 Objectives: To evaluate the presence of regional deformities and injuries in patients with Hangman fracture that affected the placement of C1 to C3 pedicle screws. Methods: Seventy-eight patients with Hangman fracture, including 67 males and 11 females, were treated in our hospital during May 2004 and May 2012. The mean age was 37.7(17 to 73)years. The interval from trauma to surgery was 3 hours to 18 days. Incomplete spinal cord injury was documented in 20 patients. According to Edward-Levine′s classification, 11 patients were type Ⅰ, 48 were type Ⅱ, 13 were type ⅡA and 6 were type Ⅲ fractures. They were evaluated by three-dimensional computed tomography preoperatively. The pedicle screw trajectories from C1 to C3 were specifically assessed to identify the presence of any deformity or injury that would preclude safe pedicle screw placement in these segments. The height of posterior arch of C1 and the width of pars interarticularis of C2 and pedicle of C3 were measured. It was considered highly risky to place a pedicle screw in one segment when its value was less than 4mm. Results: It was found 45% of type Ⅰ fractures, 23% of type Ⅱ, 38% of type ⅡA, 66% of type Ⅲ and 27% of all types complicated with injury or deformity that affected the placement of pedicle screws. Six(7.6%) cases were not fit for C1 posterior arch screw fixation, including small size of posterior arch in 2 cases and fractures of C1 posterior arch in 4. Ten(13%) cases were precluded from C2 trans-pedicle screw placement, including small pedicle size and high riding of vertebral artery and fractured fragment encased into vertebral canal or transverse process foramen. Nine(12%) cases were precluded from C3 trans-pedicle screw fixation due to small pedicle size, sclerotic pedicle and pedicle fracture or vertebral body fracture. Four patients had 2 or more types of such injuries or deformities concomitantly. Anterior approach was adopted in 17 patients, including 15 cases of C2-C3 discetomy and fusion and 2 cases of C3 corpectomy and C2-C4 fusion. Posterior approach was adopted in 55 patients, including 5 cases of C1-C3 pedicle screw fixation, 5 cases of mono-segmental C2 lag screw fixation and 45 cases of C2-C3 pedicle screw fixation. 6 patients were managed conservatively. No iatrogenic vascular or neurological injury occurred. Conclusions: There is a high incidence of regional deformity and injury in the C1 to C3 region after Hangman fracture that affects the placement of posterior screws. These factors include hypoplasia of C1 and C3 pedicles and hypoplasia of C2 pars interarticularis, pedicle sclerosis of C3, encasement of fractured segment into spinal canal or transverse process and high riding of vertebral artery.