Occipitocervical fusion angle and lower cervical spine degeneration in patients with craniocervical junction malformation / 中国组织工程研究

ABSTRACT

BACKGROUND:Occipitocervical fusion is a major method for malformation of craniocervical junction. In patients without osteoporosis, the degeneration of cervical vertebra mainly presents in the intervertebral disk. The height of the vertebral body is constant basical y. Thus, the ratio (S value) of the height of cervical disc and the height of cervical vertebra can be used to measure the degeneration of cervical vertebra. The smal S value indicates severe degeneration of cervical vertebra. OBJECTIVE:To measure the lateral radiograph of cervical vertebra in patients with craniocervical malformation undergoing occipitocervical fusion, to analyze the relationship between occipitocervical fixed angle during fusion and lower cervical spine degeneration after fusion, and to identify an optimal angle of occipitocervical fusion. METHODS:A total of 21 patients with craniocervical malformation undergoing occipitocervical fusion were included. According to the occipitocervical angle (0c-C2 angle) immediately after fusion, the patients with craniocervical malformation undergoing occipitocervical fusion were assigned to three groupsoccipitocervical angle 9°-22° group, occipitocervical angle22° group. Immediate postoperative 0c-C2 angle in 9°-22° belonged to the normal angle range. S value and JOA score in each group were measured before and after fusion, during final fol ow-up. The statistics were compared. RESULTS AND CONCLUSION:JOA scores in the occipitocervical angle 9°-22° group, occipitocervical angle22° group, were respectively, (7.3±1.7) points, (7.2±1.6) points, and (7.3±1.5) points, before fusion, and (14.2±1.5) points, (13.5±1.6) points and (13.3±1.5) points after fusion. JOA scores were improved significantly in the three groups. JOA improvement was significantly better in the occipitocervical angle 9°-22° group than that in the occipitocervical angle22° groups. Preoperative S values were respectively 0.440±0.017, 0.441±0.016, and 0.440±0.018 in the occipitocervical angle 9°-22° group, occipitocervical angle22° group, and no significant difference was detected among the three groups. No significant difference in S value was detectable in the occipitocervical angle 9°-22° group between postoperative final fol ow-up and pre-operation. The S value was significantly smal er at postoperative final fol ow-up than pre-operation in the occipitocervical angle22° groups. These results indicated that during occipitocervical fusion, occipitocervical angle should try to be normal, more than or less than normal range wil accelerate the degeneration of lower cervical spine.