The Sagittal Balance of the Cervical Spine: Radiographic Analysis of Interdependence between the Occipitocervical and Spinopelvic Alignment

Abstract

Study Design: This was a prospective clinical study.Purpose: Previous studies have indicated that cervical lordosis is a parameter influenced by segmental and global spinal sagittal balance parameters. However, this correlation still remains unclear. Therefore, a better understanding of the normal values and interdependencies between inter-segmental alignment parameters is needed. This is a preliminary analysis that helps to understand these factors.Overview of Literature: Change in global sagittal alignment is associated with poor health-related quality of life. Questions regarding which parameters play the primary roles in the progression of spinal sagittal imbalance and which might be compensatory factors remain unanswered.Methods: Prospectively, 420 adults (105 asymptomatic, 105 cervical symptomatic, 105 lumbar symptomatic, and 105 post-surgical) were selected. Whole-spine standing lateral radiographs were taken, and spinopelvic, thoracic, and cervical parameters were measured. Then, the data were analyzed using correlation coefficient test and multiple regression analysis.Results: All the parameters showed a normal distribution. The mean values of the cervical parameters are as follows: C<sub>1</sub>C<sub>2</sub> Cobb angle, −27.07°±4.3°; C<sub>2</sub>C<sub>7</sub> Cobb angle, −16.4°±5.6°; O<sub>C</sub>C<sub>2</sub> Cobb angle, −14.5°±3.8°; O<sub>C</sub>C<sub>7</sub> Cobb angle, −29.8°±5.6°; C<sub>2</sub>C<sub>7</sub> Harrison angle, 20.4°±4.3°; and C<sub>7</sub> slope, −25.4°±5.6°. The analysis of these parameters revealed no statistically significant difference between asymptomatic, symptomatic, and post-surgical patients. C<sub>7</sub> sagittal vertical axis (SVA) correlated with the C<sub>2</sub>C<sub>7</sub> Cobb angle (<i>r</i> =0.7) in all groups. No significant correlation was noted between cervical and spinopelvic parameters in asymptomatic patients. However, C<sub>1</sub>C<sub>2</sub> Cobb angle correlated significantly with pelvic incidence (PI, <i>r</i> =−0.2), lumbar lordosis (LL, <i>r</i> =0.2), and pelvic tilt (PT, <i>r</i> =−0.2) in cervical symptomatic patients. Irrespective of the patient symptom sub-group (n=420), C<sub>1</sub>C<sub>2</sub> Cobb angle correlated with LL (<i>r</i> =0.1) and C<sub>2</sub>C<sub>7</sub> Harrison angle correlated with PI and PT (<i>r</i> =0.1).Conclusions: Our results indicate significant interdependence between the spinopelvic and cervical alignment, especially in cervical symptomatic patients. In addition, strong correlation was found between the C<sub>7</sub> SVA and C<sub>2</sub>C<sub>7</sub> Cobb angle. Overall, the results of this study could help to better understand the cervical sagittal alignment and serve as preliminary data for planning surgical reconstruction procedures.

Changes in cervical sagittal alignment and the effects on cervical parameters in patients with cervical spondylotic myelopathy after laminoplasty

“…In addition, it is unlikely that the entire spine will be affected by cervical pathology. [ 18 19 ] In other words, in the example given by Matsuoka, reducing the T1 slope angle corrects all spinopelvic parameters, and this is a controversial situation. [ 9 ] In such a patient, naturally, by performing lumbar or thoracic osteotomy, it will be a better choice for the improvement of cervical deformity.…”

Clinical and radiographic parameters for patients with adult spinal deformity

“…척추 정렬의 불균형이 심화될수록, 기립 자세를 유지하기 위 한 하지와 체간의 근육 사용이 늘어나면서 피로와 통증, 장 애를 야기하게 된다 [7,8]. 이로 인한 장애와 삶의 질의 심각 한 저하는 수술적 치료를 요하게 되어 사회적, 경제적으로 막대한 손실을 야기한다 [9][10][11].…”

Comparison between selective caudal fixed screw construct and all variable screw construct in anterior cervical discectomy and fusion

“…Anterior cervical plating has been widely applied in anterior cervical discectomy and fusion (ACDF) to enhance fusion rate, improve cervical alignment, and prevent graft subsidence 1 – 5 . However, the anterior cervical plate is not without implant-related complications, including screw migration and fracture 6 – 8 .…”