枕颈融合角度与颅颈交界区畸形患者下颈椎退变的关系

Occipitocervical fusion angle and lower cervical spine degeneration in patients with craniocervical junction malformation

背景:枕颈融合是颅颈交界区畸形的主要治疗方法。对于非骨质疏松症患者,颈椎的退变主要表现在椎间盘,而椎体的高度基本保持恒定不变,所以可用颈椎间盘高度和与颈椎体高度和的比值(S值)衡量颈椎的退变,S值越小则颈椎退变越严重。目的:测量颅颈畸形枕颈融合内固定患者的颈椎侧位X射线片,分析融合过程中枕颈固定角度和融合后下颈椎退变的关系,确定最佳枕颈融合角度范围。方法:纳入因颅颈畸形行枕颈融合患者21例,根据融合后即刻枕颈角度(0c-C2角度),将颅颈畸形枕颈融合患者分为3组,即枕颈角9°-22°组、枕颈角<9°组、枕颈角>22°组,其中融合后即刻0c-C2角度在9°-22°属于正常范围。测量融合前及融合后终末随访时各组S值及JOA评分,并进行统计学比较。结果与结论:融合前枕颈角9°-22°组、枕颈角<9°组、枕颈角>22°组JOA评分分别为(7.3±1.7)分、(7.2±1.6)分、(7.3±1.5)分,融合后随访分别为(14.2±1.5)分、(13.5±1.6)分、(13.3±1.5)分,3组JOA评分均有明显改善,枕颈角9°-22°组JOA改善程度明显较枕颈角<9°组、枕颈角>22°组好。融合前S值枕颈角9°-22°组、枕颈角<9°组、枕颈角>22°组分别为0.440±0.017,0.441±0.016,0.440±0.018,3组间差异无显著性意义。枕颈角9°-22°组融合后终末随访S值与融合前S值差异无显著性意义,枕颈角<9°组、枕颈角>22°组融合后终末随访S值均较其融合前S值明显减小。提示枕颈融合内固定时枕颈角应尽量在正常范围内,超过或小于正常范围均会加速下颈椎的退变进程。

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 basically. 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 small 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 groups： occipitocervical angle 9°-22° group, occipitocervical angle 〈9° group, and occipitocervical angle 〉22° 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 follow-up. The statistics were compared. RESULTS AND CONCLUSION： JOA scores in the occipitocervical angle 9°-22° group, occipitocervical angle 〈9° group, and occipitocervical angle 〉22° 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 angle 〈9° and 〉22° 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 angle 〈9° group, and occipitocervical angle 〉22° 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 follow-up and pre-operation. The S value was significantly smaller at postoperative final follow-up than pre-operation in the occipitocervical angle 〈9° and 〉22° groups. These results indicated that during occipitocervical fusion, occipitocervical angle should try to be normal, more than or less than normal range will accelerate the degeneration of lower cervical spine.