Elsevier

World Neurosurgery

Volume 97, January 2017, Pages 471-478
World Neurosurgery

Original Article
Is It Possible To Evaluate the Ideal Cervical Alignment for Each Patient Needing Surgery? An Easy Rule To Determine the Appropriate Cervical Lordosis in Preoperative Planning

https://doi.org/10.1016/j.wneu.2016.09.110Get rights and content

Background

Cervical sagittal alignment parameters are essential to plan stages of surgery. The aims of this study were to evaluate the relationship between cervical sagittal alignment parameters and surgical outcomes after anterior cervical arthrodesis; to identify parameters linked to a better outcome; to determine the role of the T1 slope, C7 slope, cervical lordosis, and C2-C7 plumb line; and to describe an innovative method to calculate cervical lordosis. A cohort of 70 patients without cervical kyphosis was included in our retrospective study. We analyzed C7 slope, T1 slope, cervical lordosis, and the C2-C7 sagittal vertical axis (SVA). Clinical postoperative outcomes were evaluated with the Neck Disability Index (NDI) and Visual Analog Scale (VAS) score.

Results

Significant correlation was found between the C2-C7 SVA, C7 slope, T1 slope and the CL/C7 slope. Statistically significant differences were found between group 1 (NDI = 0; VAS = 0) and group 3 (NDI > 17; VAS > 5) regarding C2-C7 SVA (P = 0.0026), C7 slope (P = 0.0014), T1 slope (P = 0.0095) and CL/C7slope (P = 0.0012). A value less than 25 mm found in the C2-C7 SVA correlate with positive outcomes. C7 slope correlated with NDI and VAS (P = 0.0014). CL/C7 slope ratio is significantly correlated to NDI and VAS scores (ratio: −0.52; P = 0.0012). Patients with CL/C7 slope greater than 0.7 had better clinical outcomes.

Conclusions

Sagittal parameters are directly correlated with clinical outcome. If C7 slope increases, higher cervical lordosis is necessary to obtain a good outcome. CL/C7 slope (0.7) multiplied by C7 slope can determine the ideal lordosis.

Introduction

In the last decade, many studies elucidated the relationship between sagittal alignment and the quality of life after spinal surgery.1, 2, 3, 4, 5, 6, 7, 8 In the past few years, a considerable amount of literature has been published regarding cervical spine alignment and the relationships among different cervical parameters.9, 10, 11, 12, 13 Despite the extensive research, there is still a lack of certainty regarding the optimal amount of cervical lordosis needed to achieve postoperative success. Because of these unclear indications, surgeons usually strive to correct cervical kyphosis to attain an angle as close as possible to neutral.14 Traditionally, the C-7 sagittal vertical axis (SVA) is used to measure sagittal alignment of the thoracolumbar spine.15 Thus, current research on cervical spine is trying to adopt similar parameters.16 More specifically, the C-2 plumb line, chin brow vertical angle, and T1 slope (T1 SL) are increasingly being used.17, 18 To evaluate the effect of cervical alignment in respect to the overall sagittal spine alignment, we use 3-foot spine radiographs.

Moreover, few studies report the relationship between radiographic parameters of the cervical spine and the surgical clinical outcome. Accordingly, the effects of these cervical radiographic measurements on the outcome scores are not nearly as well defined as the global and pelvic parameters are in thoracolumbar deformities.3, 19, 20, 21 Similarly, there are few studies1, 2, 4 of cervical alignment parameters (mostly represented by lordosis between C-2 and C-7) related to postoperative clinical outcomes; they all show weak statistical correlations.

Section snippets

Objectives

Few studies have evaluated the relationship between standing cervical sagittal alignment and postoperative clinical scores for patients without cervical kyphosis receiving single and multilevel anterior cervical fusion. Therefore, our goal is to gain a better understanding of the following parameters:

  • 1.

    Evaluate the relationship between sagittal alignment of the cervical spine and patient-reported postoperative clinical scores following single and multilevel anterior cervical fusion.

  • 2.

    Identify the

Material and Methods

A series of 70 patients who were admitted to our center from 2013 through 2014 for anterior cervical discectomy and fusion were identified retrospectively. Every patient had follow-up within at least 1 year. The population in this study had several diagnoses, such as spondylosis, disc herniation with radiculopathy, and myeloradiculopathy. We excluded from this study all patients with posterior or combined approaches. Among the excluded patients were 4 patients with cervical kyphosis greater

Demographic Data

The study included 70 patients (55 with cervical radiographs including T1). The patient's ages did not significantly differ among the 3 groups. The average age was 52 years (range, 31–81 years). Thirty-one patients (45%) were male, and 39 patients (55%) were female. Most of the patients had one level pathology (n = 38; 54%) followed by two levels (n = 22; 31%), and three levels (n = 11; 15%; Table 2).

Two patients reported postoperative dysphagia that resolved within 3 weeks postoperatively. In

Discussion

Simply obtaining a better sagittal alignment was not the endpoint of our study. Because there is no agreement in the literature regarding what the correct cervical sagittal alignment should be, we opted not to divide our groups according to the alignment itself. Accordingly, the patients were separated based on their clinical postoperative scores. Once separated, we tried to find a correlation between the sagittal alignment and an easy indication to help understand what the ideal alignment

Conclusions

As we learned from thoracolumbar spine surgery, we cannot exclude the sagittal parameter when planning spinal surgery. We know that the spinopelvic parameter is more defined and widely used than the aforementioned correlations. The spinopelvic parameters are studied and used mostly on patients with preexisting sagittal imbalance and deformity, thus strongly correlating with the quality of life.1, 3, 10, 31 In our study, there was a strong correlation between C2-C7 SVA, CL/C7 SL, C7 SL, and T1

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    Conflict of interest statement: The authors declare that the article content was composed in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

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