Abstract: 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.

Key words: cervical osteotomy, kyphosis, sagittal alignment, cervical degeneration, deformity correction