Cervical sagittal balance parameters after single-level anterior cervical discectomy and fusion: Correlations with clinical and functional outcomes

Can Preoperative C2 Slope Predict Postoperative Cervical Sagittal Imbalance After Laminoplasty?

STUDY DESIGN

Retrospective study.

OBJECTIVE

To investigate the impact of preoperative C2 slope (C2S) on change in sagittal vertical axis (SVA) and postoperative cervical sagittal imbalance (CSI) after laminoplasty (LP).

METHODS

Consecutive patients who underwent LP between January 2015 and January 2022 with a minimum of 12-month follow-up were reviewed. The clinical variables and radiographic measurements were assessed. Patients were divided into improvement (ΔcSVA ≤ -10 mm), stable (-10 mm ≤ ΔcSVA <10 mm), and CSI groups (ΔcSVA≥10 mm). Correlation analysis was performed to explore the associations between ΔcSVA and preoperative factors, postoperative change and outcome variables. Multivariable logistics regression was conducted to determine the factors predicting CSI.

RESULTS

Over the 186 enrolled patients, 23 developed CSI. The CSI group presented with significantly lower preoperative cSVA, greater cervical lordosis (CL) and C2S. At the final follow-up, the CSI group presented significantly higher increase in neck pain, C2S and C7S, and greater loss in CL and range of motion at flexion position. Correlation analysis revealed that ΔcSVA is correlated positively to preoperative CL and surgical segments and negatively to preoperative C2S and cSVA. Multivariable regression revealed that lower preoperative C2S (P = 0.026) was risk factor for postoperative CSI, with 8.9 as a potential cut-off value for C2S.

CONCLUSIONS

Lower preoperative C2S slope was risk factor for post-laminoplasty CSI. The cut-off value of C2S was 8.9. Laminoplasty should be carefully considered for patients with low C2S due to risk of postoperative CSI.

Restitution of Cervical Lordosis Following Anterior Cervical Discectomy and Fusion Using a Fixed Lordotic Angle Cage

OBJECTIVES

Degenerative spine disease can result in loss of cervical lordosis. It may lead to spine misalignment, which can be evaluated using quantitative measurements of the Cobb and Harrison back (posterior tangent angle, PTA) angles. Our objective was to investigate the relationship between cervical curvature and the application of wedge-shaped allografts with a predetermined inclination angle in anterior cervical discectomy and fusion (ACDF) surgery in patients with cervical degenerative disease. Additionally, we aimed to evaluate the advantages of this technique in restoring cervical lordosis.

MATERIALS AND METHODS

During a two-year study at a single institution, we performed one-level ACDF on 60 patients using a wedge-shaped fixed-angle allograft with a preplanned inclination angle of 7°. We analyzed changes in the preoperative and postoperative Cobb and PTA angles with standard statistics.

RESULTS

Cobb angle values of the entire cervical segment were increased in 75% of patients after the surgery. Half of the patients had PTA values increased after surgery. There was a significant difference in the mean Cobb and PTA values before and after surgery.

CONCLUSION

Considering the findings of this study, an ACDF using a fixed lordotic angle wedge-shaped carbon allograft consistently restores the physiological alignment of the cervical spine and reestablishes cervical lordosis.

Impact of cervical sagittal parameters on axial neck pain in patients with cervical kyphosis

Background

Cervical sagittal alignment (CSA) is closely related with cervical disk degeneration and impacts the spinal function, especially in the setting of cervical kyphosis (CK). In this study, we evaluated the influence of cervical sagittal parameters on the development of axial neck pain (ANP) in patients with CK.

Methods

Data pertaining to 263 patients with CK who visited the outpatient department of our hospital between January 2012 and December 2018 were retrospective analyzed. The most common symptoms of ANP were neck pain, stiffness, or dullness. Visual analog scale (VAS) was used to evaluate ANP. The following radiographic parameters were evaluated: CK types, C2-7 sagittal vertical axis (SVA), thoracic inlet angle (TIA), T1 slope, neck tilt (NT), cranial tilt, and cervical tilt. Sagittal alignment of CK was classified into 2 types: global and regional type. Multivariate logistic regression analysis was performed to identify risk factors for ANP.

Results

Patients who complained of ANP were categorized as ANP group (VAS score ≥ 3; n = 92), while those without ANP were categorized as non-ANP group (VAS score < 3; n = 171). There was no significant between-group difference with respect to age (P = 0.196), gender (P = 0.516), TIA (P = 0.139), NT (P = 0.676), CK type (P = 0.533), cranial tilt (P = 0.332), cervical tilt (P = 0.585), or cervical disk degeneration (P = 0.695). The T1 slope and C2-7 SVA in the ANP group were significantly greater than that in the non-ANP group (P < 0.05). On multivariate logistic regression, C2-7 SVA [

odds ratio (OR) 2.318, 95% confidence interval 1.373–4.651, P = 0.003) and T1 slope (OR 2.563, 95% CI 1.186–4.669, P = 0.028) were identified as risk factors for ANP.

Conclusions

Our findings suggest a significant effect of cervical sagittal parameters on the occurrence of ANP in patients with CK. Greater T1 slope and larger C2-7 SVA may lead to the development of neck pain.

A review of cervical spine alignment in the normal and degenerative spine

With recent advancements in surgical spine technology and techniques, the importance of regional and global spine alignment has become an important factor in surgical planning. Our review aims to consolidate the current literature on cervical and global alignment parameters and its relationship to cervical symptomatology, quality of life (QOL), requirements for surgery, potential surgical complications and health-related quality of life (HRQOL) outcomes.