The Clinical Investigation Of Posterior Occipital-axis Screw-rod Temporary Fixation For The Type Odontoid Ⅱ Fracture

Objective:To investigate the feasibility of posterior occipital-axis screw-rod temporary fixation for the typeⅡodontoid fracture.Methods:Retrospective analysis 46 cases who suffered from the typeⅡodontoid fracture of posterior operation indication treated in my department from January 2010to August 2016.19 cases in the O-C₂ group made up of 11 males and 8 females,conducted by posterior occipital-axis screw-rod temporary fixation.27 cases in the C1-C2 group consisted of 18 males and 9 females,operated by posterior atlantoaxial non-fusion operation.When the fractures were osteounion by CT photograph,the secondary surgeries were carried out to remove the internal fixation.Compare the two groups of operation time,intraoperative blood loss,incision length,inpatient days,bone fusion time and VAS score,ASIA impairment scale,ROM and neck stiffness.Results:Successful operation was performed on the 46 cases.The restoration was satisfactory and there was no damage to the vertebral artery,nerve roots and spinal cord.All cases were followed up from 6 to 18（mean 9.67±1.71）months.There was no increase in symptoms,loosening of internal fixation,or fracture of the screw rod in both groups.All patients had bony fusions proved by CT scans in 3 to 12 months after the first surgery.The operation time were（105.11±29.43）min in O-C₂ group and（122.62±28.19）min in C₁-C₂ group.The incision length was（9.81±1.36）cm in O-C₂group and（8.53±0.62）cm in C1-C2 group.There were significant statistical difference in both operation time and incision length between the two groups（P<0.05）.There was no significant statistical difference in average age,intraoperative blood loss,inpatient days,bone fusion time,VAS scores and neck stiffness at the last follow-up between the two groups（P>0.05）.The ROM of cervical vertebra varied in O-C₂ group after the first surgery:left and right rotational angle:（11.56±2.19）°,anteversion angle:（8.92±3.11）°,retroversion angle:（5.38±3.79）°,and at the last follow-up:left and right rotational angle:（83.44±4.82）°,anteversion angle:（31.50±3.79）°,retroversion angle:（21.96±3.61）°.The ROM of cervical vertebra varied in C₁-C₂ group after the first surgery:left and right rotational angle:（9.24±3.08）°,anteversion angle:（18.36±4.17）°,retroversion angle:（15.49±4.88）°,and at the last follow-up:left and right rotational angle:（82.75±6.21）°,anteversion angle:（29.65±4.53）°,retroversion angle:（23.77±3.85）°.There was statistically significant difference between interclass results after the first and final follow-up of the ROM（P<0.05）,there was a distinction in the final follow-up results,but no statistically significant in two groups（P>0.05）.Conclusion:1.Primary posterior occipital-axis screw-rod temporary fixation followed by second stage instruments removed when bony fusions for the typeⅡodontoid fracture can preserve C_1-2 joint rotation function furthest and improve patients’postoperative quality of life obviously.There was little difference in the effect compared with posterior atlantoaxial non-fusion operation,and it is a simple,safety and effective technology.2.It can be an alternative for patients who suffered the typeⅡodontoid fracture but have greater potential risk for posterior atlantoaxial screw-rod fixation.