颈前路经椎间隙后缘截骨治疗退变性僵硬型颈椎后凸畸形

目的 总结颈前路经椎间隙后缘截骨（anterior trans-intervertebral osteotomy，ATIVO）技术治疗退变性僵硬型颈椎后凸畸形的治疗策略、方法及临床疗效。方法 回顾性分析2012年至2016年共47例因退变性僵硬型颈椎后凸畸形采用ATIVO技术进行畸形矫形的病例。其中，男性29例，女性18，年龄38~73岁。共83节段进行颈前路经椎间隙后缘截骨（C3/4 16例；C4/5 24例；C5/6 25例；C6/7 16例；C7/T1 2例）。单节段17例，双节段24例（跳跃节段6例），3节段6例。经颈前路经椎间隙进行截骨，切除椎间盘及后纵韧带，两侧切除部分钩椎关节并进行松解，椎体后缘截骨面潜行约10°~15°，至少保留2/3终板。术中使用椎间撑开器、带角度椎间融合器、调整颈下软枕及改变颈后伸角度等综合方式进行后凸畸形矫形。融合方式采用填充人工骨颗粒的椎间融合器，固定方式采用自锁式椎间融合器或前路钛板。应用脊柱显微镜、脊柱骨动力系统（气动磨钻）进行截骨操作。应用皮节体感诱发电位、运动诱发电位、自由肌电进行联合功能监测。手术前后通过X线、CT进行影像学评估C2-C7 Cobb角、颈椎矢状面垂直轴（cervical sagittal vertical axis，cSVA）及截骨效果。使用疼痛视觉模拟评分（Visual Analogue Score，VAS），颈椎功能障碍指数（Neck Disability Index，NDI），日本骨科协会改良颈椎评分（modified Japanese Orthopaedic Association Score，mJOA）对临床疗效进行评价。结果 47例患者均获得最少1年随访，平均随访时间20个月（12个月至5年）。平均手术时间109 min （55~140 min）、出血量46 mL （25~110 mL）。术后3例患者出现肩部疼痛，5例患者出现C5神经根麻痹症状，无椎动脉损伤病例。末次随访时VAS、NDI、mJOA分别由术前7.2±1.5、64.5±17.4、10.5±0.9改善至2.6±1.7、34.8±21.6、14.5±1.3。CT显示截骨节段均获融合。C2-C7 Cobb角由13.6°±5.1°改变为-7.4°±3.6°；截骨节段矫形能力7.4°（5.3°~9.6°）/节段；C2-C7矢状面垂直轴由（55.7±13.8） mm改变为（31.4±8.2） mm。结论 采用颈前路经椎间隙后缘截骨技术治疗退变性僵硬性后凸畸形可获得良好的疗效，可显著纠正颈椎后凸畸形，纠正整体颈椎曲度，并阻止颈椎向前的矢状位失平衡趋势。该截骨技术骨量损失小，不影响椎间融合率，可多节段联合应用提高矫形效果。适用于由椎间盘、钩椎关节等原因导致的颈椎僵硬性后凸畸形。

Surgical treatment of degenerative rigid cervical kyphosis by anterior trans-intervertebral osteotomy

Objective To review technique, evaluate surgical outcomes and the treatment strategy of anterior trans-intervertebral osteotomy (ATIVO) for degenerative rigid cervical kyphosis.Methods A retrospective analysis was performed based on 47 cases of degenerative cervical kyphosis from 2012 to 2016, using ATIVO for deformity correction. Totally 29 males, 18 females, aged 38-73 years. AVTIO was performed for total of 83 segments (16 cases of C3/4, 24 cases of C4/5, 25 cases of C5/6, 16 cases of C6/7, 2 cases of C7/T1). There were 17 cases in single segment, 24 cases in double segment (6 cases in jumping segment), and 6 cases in 3 segments. Intervertebral disc and posterior longitudinal ligament (PLL) were removed through the intervertebral space. Bilateral saddle joints were partially resected and released. The osteotomy surface of the vertebral body was about 10-15 degrees, at least 2/3 endplate was retained. To improve kyphosis correction, intraoperative intervertebral distractor and, cage with appropriate size and angle was used, the pillow was adjusted and the neck extension angle was changed. Self-locking cage or cage with plate were used for fusion and fixation. Microscopy and high-speed drill were used to perform osteotomy. IONM was performed by using DSEP, MEP and free-run EMG. The C2-C7 Cobb angle, cervical sagittal vertical axis (cSVA) and osteotomy effect were evaluated by X-ray and CT before and after operation. Visual Analogue Score (VAS), Neck Disability Index (NDI),modified Japanese Orthopaedic Association Score (mJOA) were used to evaluate the clinical efficacy.Results All 47 patients were followed up for at least one year, with an average follow-up time of 20 months (12 months to 5 years). The average operative time was 109 minutes (55-140 minutes) and the bleeding volume was 46 mL (25-110 mL). There were 3 cases of shoulder pain, 5 cases of C5 nerve root palsy and no vertebral artery injury. At the last follow-up, VAS, NDI and mJOA were improved to 2.6±1.7, 34.8±21.6, 14.5±1.3 (paired T test, P<0.01) by 7.2±1.5, 64.5±17.4 and 10.5±0.9 before operation. CT showed that the osteotomy segment was bone union. The C2-C7 Cobb angle was changed from 13.6±5.1 to -7.4±3.6 degrees; the average segmental correction angle was 7.4° (5.3°-9.6°) per segment, and the C2-C7 SVA was changed from (55.7±13.8)mm to (31.4 ±8.2)mm (P<0.01).Conclusion The ATIVO technique has satisfied clinical outcomes for rigid degenerative cervical kyphosis. The advantages of AVTIO is:it could correct cervical kyphosis, restore the overall curvature of the cervical spine, and prevent from the trend of sagittal imbalance. The AVTIO procedure has minor bone loss and does not affect the fusion rate. It can be performed with multiple segments to improve the effect of deformity correction. It is suitable for cervical kyphotic deformities caused by intervertebral disc and saddle joint.