Treatment of odontoid process fractures with anterior percutaneous screw fixation / 中华骨科杂志

ABSTRACT

Objective To explore a new method in the treatment of odontoid pr ocess fracture with a self-designed screw and anterior percutaneous odontoid fix ation. Methods Computerized tomography (CT) was used to measure the coronal and sagittal external diameter of the base of odontoid process, the length of the od ontoid process, the total height of the axis and the angle between the axial lin e of the odontoid process and the vertical line of the anterosuperior border of the C3 vertebral body in 40 normal adults aged from 20 to 45 years. Ten odontoid process fractures were fixed with cannulated anterior odontoid screws and monit ored under fluoroscope. According to Anderson's classfication, there were 4 of t ype Ⅱand 6 of type Ⅲ. 4 had no any displacement of the dens, 3 had displacemen t less than 5 mm, and 3 had displacement of 5 mm or more. The fractures were fre sh in 8, and the other 2 were old. Each fracture was fixed by one screw, and ant erior bone-graft was performed in old fracture after screw fixation. Results The coronal external diameter of the base of odontoid process was (8.8?1.2) mm, wh ile the sagittal external diameter was (10.9?1.0) mm, the length of the odontoi d process was (14.2?1.2) mm, the total height of the axis was (38.2?1.8) mm an d the angle between the axial line of the odontoid process and the vertical line of the anterosuperior border of the C3 vertebral body was 23.1??1.4?. Satis factory results were achieved in all patients, and all screws were in good posit ion. No neurological deterioration occurred. After a mean follow-up of 19 months (range, 10 to 25 months), 8 cases showed radiographic union, while 2 nonunion. Neither clinical symptoms nor screw loosening or breakage occurred. Conclusion The direct anterior percutaneous screw fixation is practical for fractures of t he dens with appropriate instrumentation, as long as the surgeon is familiar wit h the topographic anatomy and makes sure the insertion point, the depth and the angle on percutaneous insertion of the screws, the satisfactory outcome will be obtained. There is no stiffening of the C1,2 and the motion limitation. The ant erior percutaneous procedure is surgically less traumatic than the conventional cervical approaches. One screw is optimal for this procedure.