Should cervicothoracic junctions be avoided in long cervical posterior fusion surgery? Analysis of clinical and radiologic outcomes over two years.

Purpose: This study aimed to confirm the usefulness of surgery that avoids the cervicothoracic junction (CTJ) by comparing the clinical and radiographic outcomes after posterior cervical fusion at C5/6 with those at C7/T1.

Methods: Patients who underwent laminectomy and posterior cervical instrument fusion for cervical spondylotic myelopathy (CSM) from 2012 to 2019 were retrospectively reviewed and divided according to whether the end level was at C5/6 (group 1) or C7/T1 (group 2). Demographic variables and incidence of distal junctional kyphosis (DJK) were compared between the groups. Clinical outcomes (visual analog scale [VAS] score for arm and neck pain and the Neck Disability Index value) and radiologic outcomes (T1 slope, cervical lordosis, segmental lordosis, C2-7 sagittal vertical axis, T1 slope-cervical lordosis mismatch) were compared over time.

Results: Sixty-seven patients were included. There were 32 patients in group 1 and 35 in group 2. The VAS score for neck pain was significantly lower in group 1 than in group 2 at 2 years after surgery (p = 0.03). The C2-7 sagittal vertical axis was significantly larger in group 2 than in group 1 at 1 year and 2 years postoperatively (p = 0.04). The incidence of DJK was higher in group 2 than in group 1 (28.57% vs 9.37%, p = 0.04).

Conclusion: This study found that when CTJs are included in the posterior cervical long fusion surgery, although it would be better than preoperation, postoperative kyphosis and consequent neck pain may progress. The results of this study advocate the concept of avoiding CTJ fusion if possible.