Tan Mingsheng, Wang Huimin, Wang Yunting, Zhang Guangbo, Yi Ping, Li Zirong, Wei Hongyu, Yang Feng
Department of Orthopedics Surgery, China-Japan Friendship Hospital, Ministry of Health, Beijing, People's Republic of China.
Spine (Phila Pa 1976). 2003 May 1;28(9):888-95. doi: 10.1097/01.BRS.0000058719.48596.CC.
This study is a result of manual and radiologic measurements of 50 isolated anatomic specimens of C1 and five patients of atlantoaxial instability treated by screw fixation via posterior arch and lateral mass.
To investigate the feasibility of screw placement via posterior arch and lateral mass in atlas.
Several types of posterior approaches have been adopted for stabilization and fusion of atlantoaxial complex. Before this study, Gallie in 1939 gave a report on a posterior wiring technique that depended on a structural bone graft. Since then, double-looped wiring with two bone grafts and Halifax clamp technique had been introduced. A transarticular screw fixation technique was introduced by Magerl and Seeman in 1987, and a C1 lateral mass screw fixation technique was described by Harms in 2001. However, the feasibility of screw fixation in atlas via posterior arch and lateral mass has not been addressed until now.
Fifty dry samples of atlas were measured manually and radiologically with vernier calipers, protractors, and CT. The parameters of posterior arch, lateral mass, vertebral artery groove, axis length of screw path via posterior arch and lateral mass, the entry point, and screw direction were measured. Five patients of atlantoaxial instability were treated with this technique and the radiographs and CT scans were evaluated after surgery.
The longest trajectory distance of the screw path was about 30 mm. The outer thickness at the thinnest part of groove was 4.58 mm, and it was found to be <4 mm in four cases (8%). The entry point is 18-20 mm lateral to the midline and 2 mm superior to the inferior border of posterior arch. The direction of screw placement is perpendicular to the coronal plane and about 5 degrees cephalad to the transverse plane. Ten screws via posterior arch and lateral mass were placed properly, without incidence of nerve or blood vessel injury in clinical practice.
Atlas is capable for screw fixation via its posterior arch and lateral mass.
本研究是对50个孤立的C1解剖标本以及5例经后路椎弓根和侧块螺钉固定治疗的寰枢椎不稳患者进行手动和放射学测量的结果。
探讨经寰椎后路椎弓根和侧块置入螺钉的可行性。
已采用多种后路手术方法来稳定和融合寰枢复合体。在本研究之前，1939年加利报告了一种依赖结构性植骨的后路钢丝技术。此后，引入了双环钢丝联合两块植骨技术和哈利法克斯夹技术。1987年马格勒和泽曼引入了经关节螺钉固定技术，2001年哈姆斯描述了C1侧块螺钉固定技术。然而，经寰椎后路椎弓根和侧块螺钉固定的可行性至今尚未得到探讨。
使用游标卡尺、量角器和CT对50个寰椎干标本进行手动和放射学测量。测量椎弓根、侧块、椎动脉沟、经后路椎弓根和侧块的螺钉路径轴长、进针点和螺钉方向等参数。对5例寰枢椎不稳患者采用该技术治疗，并在术后对X线片和CT扫描进行评估。
螺钉路径的最长轨迹距离约为30mm。沟最薄处的外侧厚度为4.58mm，4例（8%）发现其<4mm。进针点位于中线外侧18 - 20mm，后弓下缘上方2mm。螺钉置入方向垂直于冠状面，相对于横断面头侧约5度。在临床实践中，10枚经后路椎弓根和侧块的螺钉均正确置入，无神经或血管损伤发生。
寰椎能够经其后路椎弓根和侧块进行螺钉固定。
