前路经枢椎体至寰椎侧块螺钉内固定的解剖学研究及初步临床应用

ANATOMICAL STUDY OF ANTERIOR APPROACH SCREW FIXATION THROUGH C_2 VERTEBRAL BODY INTO C_1 LATERAL MASS AND ITS PRIMARY CLINICAL APPLICATION

目的为临床行前路经枢椎体至寰椎侧块螺钉内固定提供理论依据。方法对21具成人寰枢椎标本进行解剖学测量,计算前路经枢椎体至寰椎侧块螺钉内固定术中螺钉走向的最小外偏角α、最大外偏角β和最大后倾角γ;21具寰枢椎标本摄正、侧位X线片,在X线片上测量此术式中螺钉走行的α、β和γ,将标本上所测的数据与在X线片上测的数据作统计学分析,并在标本上模拟这一术式。2004年10月～2006年7月,此术式应用于临床治疗5例陈旧性寰枢椎脱位患者,男3例,女2例;年龄30～55岁;病程3～24个月。脊髓损伤程度按Frankel分级,B级1例,C级2例,D级2例。术后摄X线片及CT。结果利用直角三角形的反正弦原理,由各个测量指标计算出的α、β及γ,与在X线片上所测量出的α、β及γ比较差异无统计学意义(P>0.05)。故将数据合并后α为14.0±1.6°,β为30.0±2.3°,γ为29.0±2.9°。模拟术式中实际应用角度:α为11.2±1.6°,β为28.8±2.3°,γ为29.3±2.9°。所有寰枢椎标本经固定后肉眼观察螺钉全部位于寰枢椎中,未出现螺钉穿出寰枢椎椎体外和寰椎侧块上、椎管内及损伤椎动脉。X线片示所有螺钉均位于理想位置。临床应用5例患者术后随访6～30个月,平均14个月,X线片及CT均示效果良好;术后3个月脊髓功能恢复,采用改良Frankel分级,C级1例,D2级1例,D3级3例。结论只要正确掌握螺钉的进钉方向,采用前路经枢椎体至寰椎侧块螺钉内固定治疗寰枢椎脱位则是安全可行的;但只能使寰椎在复位的位置获得暂时稳定,尚需一期或二期加行后路寰枢植骨融合,以达到永久的牢固固定。

Objective To explore the anatomic basis for the anterior approach screw fixation through the Cz vertebral body into the C1 lateral mass and to investigate its primary clinical application. Methods Twenty-one adult corpse specimens were anatomically measured. The minimum lateral angle α, the maximum lateral angle β, and the maximum posterior angle γ were calculated based on the data from the anatomic measurement. All the specimens were given an X-ray examination, the minimum lateral angle α, the maximum lateral angle β, and the maximum posterior angle γ were measured. The statistical analysis was made on the data obtained from the calculation in the specimens and the measurement in the X-ray films. The simulation of the approach was made on the specimen. From October 2004 to July 2006, the simulated approach was used in 5 patients （3 males, 2 females; age, 30-55 years; illness course, 3 months-2 years） with the old atlanto-axial joint dislocation . The Frankel grading system revealed the spinal cord injury degree as follows： 1 patient was in Grade B, 2 in Grade C, and 2 in Grade D. All the patients were treated with this surgical approach. The postoperative X-ray and CT examinations were performed. Results Angle α was 14.0±1.6°,β was 30.0±2.3°,γ was 29.0±2.9°. No significant difference existed between the angles calculated in the specimens and measured in the X-ray films （P〉0. 05）. The angles for the practical application during operation were as follows： α was 11.2±1.6°,β was 28.8±2.3°,γ was 29.3±2.9°. The follow-up for an average of 14 months revealed that 1 patient recovered to Grade C, 1 to Grade D2, and 3 to Grade D3 in the spinal cord function according the modified Frankel grading system. Conclusion The anterior approach screw fixation through the C2 vertebral body into the C1 lateral mass is feasible and safe in treatment of the old atlantoaxial joint dislocation if the screw insertion is exact in direction. This technique only makes the atlas temporarily stable, and so the posterior bone graft should be added into the atlanto-axial joint immediately in the one- or two-stage operation so as to achieve a long-lasting stability.