Analysis of the risk factors for increasing cervical sagittal vertical axis after cervical laminoplasty for cervical spondylotic myelopathy

Horizontal Gaze Assessment: An Extensive Narrative Review

OBJECTIVE

Bipedalism was a significant milestone in the evolutionary development of Homo sapiens sapiens, influencing neocortical evolution and subsequent behavioral changes. Coordinated visual and sensory inputs are crucial for posture, environmental interaction, and surgical planning, with horizontal gaze being a pivotal parameter. This narrative review aims to explore various geometric measures used to assess horizontal gaze in patients, highlighting their applications in surgical planning.

METHODS

A literature review was conducted in indexed databases using Mesh terms like "Cervical Vertebrae" and "Visual Fields" along with keywords such as "horizontal gaze" and "sagittal spine parameters." Among 477 initially identified articles, 41 were selected for inclusion after rigorous filtering.

RESULTS

The most recognized method for assessing horizontal gaze is the Chin Brow Vertical Angle (CBVA), initially described in patients with ankylosing spondylitis. Clinical photography is employed as a tool for CBVA calculation, while other measures like McGregor slope and Slope of the Line of Sight have been considered as alternatives to CBVA. Each method presents its unique advantages and limitations.

CONCLUSIONS

This review highlights the need for further research into horizontal gaze measurement methods. Developing novel approaches to determine horizontal gaze can significantly enhance surgical planning and, consequently, improve patient outcomes. The ongoing exploration of these geometric measures offers promising prospects for advancing the field and optimizing patient care.

Current Concepts of Cervical Spine Alignment, Sagittal Deformity, and Cervical Spine Surgery

There are not many reports on cervical spine alignment, and only a few analyze ideal surgical approaches and optimal amounts of correction needed for the various types of deformity. We comprehensively reviewed the present literature on cervical spinal deformities (with or without myelopathy) and their surgical management to provide a framework for surgical planning. A general assessment of the parameters actually in use and correlations between cervical and thoracolumbar spine alignment are provided. We also analyzed posterior, anterior, and combined cervical surgical approaches and indications for the associated techniques of laminoplasty, laminectomy and fusion, and anterior cervical discectomy and fusion. Finally, on the basis of the NDI, SF-36, VAS, and mJOA questionnaires, we fully evaluated the outcomes and measures of postoperative health-related quality of life. We found the need for additional prospective studies to further enhance our understanding of the importance of cervical alignment when assessing and treating cervical deformities with or without myelopathy. Future studies need to focus on correlations between cervical alignment parameters, disability scores, and myelopathy outcomes. Through this comprehensive literature review, we offer guidance on practical and important points of surgical technique, cervical alignment, and goals surgeons can meet to improve symptoms in all patients.

Multilevel Laminoplasty for CSM: Is C3 Laminectomy Better Than C3 Laminoplasty at the Superior Vertebra?

INTRODUCTION

In a multilevel cervical laminoplasty operation for patients with cervical spondylotic myelopathy (CSM), a partial or complete C3 laminectomy may be performed at the upper level instead of a C3 plated laminoplasty. It is unknown whether C3 technique above the laminoplasty affects loss of cervical lordosis or range of motion.

METHODS

Patients undergoing multilevel laminoplasty of the cervical spine (C3-C6/C7) at a single institution were retrospectively reviewed. Patients were divided into two cohorts based on surgical technique at C3: C3-C6/C7 plated laminoplasty ("C3 laminoplasty only", N = 61), C3 partial or complete laminectomy, plus C4-C6/C7 plated laminoplasty (N = 39). All patients had at least 1-year postoperative X-ray treatment.

RESULTS

Of 100 total patients, C3 laminoplasty and C3 laminectomy were equivalent in all demographic data, except for age (66.4 vs. 59.4 years, p = 0.012). None of the preoperative radiographic parameters differed between the C3 laminoplasty and C3 laminectomy cohorts: cervical lordosis (13.1° vs. 11.1°, p = 0.259), T1 slope (32.9° vs. 29.2°, p = 0.072), T1 slope-cervical lordosis (19.8° vs. 18.6°, p = 0.485), or cervical sagittal vertical axis (3.1 cm vs. 2.7 cm, p = 0.193). None of the postoperative radiographic parameters differed between the C3 laminoplasty and C3 laminectomy cohorts: cervical lordosis (9.4° vs. 11.2°, p = 0.369), T1 slope-cervical lordosis (21.7° vs. 18.1°, p = 0.126), to cervical sagittal vertical axis (3.3 cm vs. 3.6 cm, p = 0.479). In the total cohort, 31% had loss of cervical lordosis >5°. Loss of lordosis reached 5-10° (mild change) in 13% of patients and >10° (moderate change) in 18% of patients. C3 laminoplasty and C3 laminectomy cohorts did not differ with respect to no change (<5°: 65.6% vs. 74.3%, respectively), mild change (5-10°: 14.8% vs. 10.3%), and moderate change (>10°: 19.7% vs. 15.4%) in cervical lordosis, p = 0.644. When controlling for age, ordinal regression showed that surgical technique at C3 did not increase the odds of postoperative loss of cervical lordosis. C3 laminectomy versus C3 laminoplasty did not differ in the postoperative range of motion on cervical flexion-extension X-rays (23.9° vs. 21.7°, p = 0.451, N = 91).

CONCLUSION

There was no difference in postoperative loss of cervical lordosis or postoperative range of motion in patients who underwent either C3-C6/C7 plated laminoplasty or C3 laminectomy plus C4-C6/C7 plated laminoplasty.

Cervical alignment and clinical outcome of anterior cervical discectomy and fusion vs. anterior cervical corpectomy and fusion in local kyphotic cervical spondylotic myelopathy

Background

Cervical local kyphosis (CLK) is a common degenerative disorder with a potentially debilitating and intractable condition. Currently, there is still debate on the optimal treatment of local kyphotic cervical spondylotic myelopathy (LKCSM) via different anterior approaches.

Objective

The objective of this study was to evaluate the surgical efficacy of anterior cervical discectomy and fusion (ACDF) vs. anterior cervical corpectomy and fusion (ACCF) for the treatment of LKCSM. In addition, the cervical sagittal alignment parameters and axial symptoms (AS) severity after CLK correction were analyzed.

Materials and methods

From January 2016 and December 2020, 104 patients who suffered LKCSM were retrospectively reviewed. These patients underwent ACDF (n = 53) and ACCF (n = 51). Pre- and postoperatively, cervical sagittal alignment parameters were measured on the lateral X-rays, including local kyphotic angles (LKA), C2-7 Cobb angle, T1 slope, and C2-7 sagittal vertical axis (C2-7 SVA). The neurological recovery rate was calculated according to the Japanese Orthopedic Association (JOA) score. The AS severity was evaluated using Neck Disability Index (NDI).

Results

Significant differences (P < 0.05) were demonstrated between ACDF and ACCF groups regarding LKA, LKA correction, C2-7 Cobb angle, T1 slope, C2-7 SVA, NDI, NDI recovery and NDI ranking system. However, no significant differences (P > 0.05) existed in JOA score, recovery rate, and neurological recovery rate grade. In both groups, significant differences (P < 0.05) were demonstrated between pre- and postoperative LKA, T1 slope, C2-7 Cobb angle, C2-7 SVA, JOA score, and NDI. LKA correction showed the positive correlations with the recovery rate (r = 0.48, P < 0.001), and with the NDI recovery in ACDF group (r = 0.49, P < 0.001) and in ACCF group (r = 0.55, P < 0.001).

Conclusions

LKCSM with ≤3 segments of spinal cord compression can be improved with either ACDF or ACCF, resulting in satisfactory neurological outcomes. CLK correction can significantly improve the neurological function and AS, and increase the T1 slope and C2-7 SVA. However, ACDF was more favorable than ACCF in the CLK correction.

Cervical alignment and clinical outcome of open-door laminoplasty vs. laminectomy and instrumentation in kyphotic multilevel cervical degenerative myelopathy

INTRODUCTION

The aim of this study was to determine whether the sagittal lordotic alignment, clinical outcomes and axial symptoms (AS) could be improved by kyphotic correction through the posterior approach for the treatment of multilevel cervical degenerative myelopathy (CDM) and to further analyze the changes of cervical spinal alignment parameters after correction of kyphosis. The hypothesis was that correction of kyphosis can improve the severity of AS and neurological recovery.

MATERIALS AND METHODS

We retrospectively reviewed 109 patients who suffered from multilevel CDM combined with kyphosis. The patients had undergone open-door laminoplasty (Group LP, 53 patients) and laminectomy with instrumentation (Group LI, 56 patients) between January 2014 and December 2018. Cervical spinal alignment parameters, including curvature index (CI), T1 slope, C2-7 Cobb angle, C2-7 SVA, were measured on the pre- and postoperative lateral radiographs. The recovery rate was calculated based on the Japanese Orthopedic Association (JOA) score. AS severity was quantified using Neck Disability Index (NDI). A P value less than 0.05 was considered to be significant.

RESULTS

Analyses of postoperative follow-up data showed significant differences (P < 0.001) in CI, correction of CI, C2-7 Cobb angle, T1 slope, C2-7 SVA and NDI between Group LP and LI, but no significant differences in JOA score (P = 0.23) and recovery rate (P = 0.13). There were significant differences (P < 0.001) in CI, T1 slope, C2-7 Cobb angle, C2-7 SVA, JOA score, and NDI between pre- and postoperative follow-up in both groups. Correction of CI showed negative correlation with AS severity (r = -0.51, P < 0.001), and no association with recovery rate (r = 0.14, P = 0.15).

CONCLUSIONS

Satisfied neurological improvement was achieved by LP and LI for multilevel CDM combined with kyphosis. Cervical kyphotic correction produced significant improvement of AS and increase of T1 slope and C2-7 SVA. However, the kyphotic correction may not be associated with better neurological recovery in the short-term postoperative period.

Predictors for cervical kyphotic deformity following laminoplasty: a systematic review and meta-analysis

OBJECTIVE

Laminoplasty is a common treatment for cervical spondylotic myelopathy (CSM) and for ossification of the posterior longitudinal ligament (OPLL). However, approximately 21% of patients undergoing laminoplasty develop cervical kyphotic deformity (KD). Because of the high prevalence rate of KD, several studies have sought to identify predictors for this complication, but the findings remain highly inconsistent. Therefore, the authors performed a systematic review and meta-analysis to establish reliable preoperative predictors of KD.

METHODS

PubMed, Scopus, and Web of Science databases were used to systematically extract potential references. The first phase of screening required the studies to be written in the English language, involve patients treated for CSM and/or OPLL via laminoplasty, and report postoperative cervical KD. The second phase required the studies to provide more than 10 patients and include a control group. The mean difference (MD) and odds ratio (OR) were calculated for continuous and dichotomous parameters. Study quality was evaluated using the Newcastle-Ottawa Scale. CSM and OPLL patients were further assessed by performing subgroup analyses.

RESULTS

Thirteen studies comprising patients who developed cervical KD (n = 296) and no KD (n = 1254) after receiving cervical laminoplasty for CSM or OPLL were included in the meta-analysis. All studies were retrospective cohorts and were rated as high quality. In the combined univariate analysis of CSM and OPLL patients undergoing laminoplasty, statistically significant predictors for postoperative KD included age (MD 2.22, 95% CI 0.16-4.27, p = 0.03), preoperative BMI (MD 0.85, 95% CI 0.06-1.63, p = 0.04), preoperative C2-7 range of flexion (MD 10.42, 95% Cl 4.24-16.59, p = 0.0009), preoperative C2-7 range of extension (MD -4.59, 95% CI -6.34 to -2.83, p < 0.00001), and preoperative center of gravity of the head to the C7 sagittal vertical axis (MD 26.83, 95% CI 9.13-44.52, p = 0.003). Additionally, among CSM patients, males were identified as having a greater risk for postoperative KD (OR 1.73, 95% CI 1.02-2.93, p = 0.04).

CONCLUSIONS

The findings from this study currently provide the largest and most reliable review on preoperative predictors for cervical KD after laminoplasty. Given that several of the included studies identified optimal cutoff points for the variables that are significantly associated with KD, further investigation into the development of a preoperative risk scoring system that can accurately predict KD in the clinical setting is encouraged. PROSPERO registration no.: CRD42022299795 (https://www.crd.york.ac.uk/PROSPERO/).

Relationship between K-line distance and surgical outcome in cases of laminoplasty for cervical ossification of the posterior longitudinal ligament

Although previous studies indicate that changes in cervical alignment after laminoplasty and dynamic factors influence surgical outcomes of cervical ossification of the posterior longitudinal ligament (OPLL), the relationship between the surgical outcomes, the distance between the kyphosis-line (K-line) and OPLL, and dynamic factors have not yet been quantitatively evaluated. The purpose of the present study was to analyze the relationship between ΔK-line distance and surgical outcomes in cases of laminoplasty for OPLL of the cervical spine. We retrospectively reviewed 46 consecutive patients (33 men and 13 women) with cervical OPLL who underwent laminoplasty. "K-line distance" was measured as the minimum interval between the K-line and OPLL on lateral radiographs. The following factors were analyzed: K-line distance in neutral, flexion, and extension neck positions, ΔK-line distance, preoperative C2-7 range of motion (ROM), preoperative segmental ROM, preoperative C2-7 lordotic angle, occupying ratio of the OPLL, disease duration, preoperative and postoperative Japanese Orthopaedic Association (JOA) score, and recovery rate. Patients were divided into flexion K-line (+) and flexion K-line (-) groups. We then analyzed the influence of the K-line distance on surgical outcomes and conducted multivariate analysis to analyze the factors affecting surgical outcomes. The JOA score recovery rate in the flexion K-line (-) group was significantly lower than that in the flexion K-line (+) group (P = .024). The ΔK-line distance was significantly negatively correlated with the JOA score recovery rate (r = -0.531, P < .001). Additionally, multivariate analysis showed that ΔK-line distance (OR = -2.143, P = .015) was negatively correlated with the JOA score recovery rate. The ΔK-line distance is considered useful for the quantitative evaluation of dynamic factors and static compression factors due to OPLL through the measurement of dynamic radiographic images.

Clinical and radiological efficacy of corpectomy and anterior stabilization with titanium mesh cages in patients with myelopathic syndrome associated with cervical spine degenerative di

The aim of this study was to research the clinical and radiological efficacy of  corpectomy and anterior stabilization with titanium mesh cages in patients with myelopathic syndrome associated with cervical spine degenerative diseases.

Material and methods. A retrospective observational cohort study was performed. The study included medical records of patients with cervical myelopathy associated with degenerative diseases of the cervical spine who underwent corpectomy and  anterior stabilization with titanium mesh cages. Clinical and instrumental parameters were assessed.

Results. The study included 28  medical records of respondents who underwent corpectomy and anterior stabilization with titanium mesh implants. The average age of patients was 61.9 ± 11.3 years, males prevailed (60.7 %). By the 3rd month of  postoperative follow-up, the severity of myelopathy significantly decreased (p˂0.001). After 12  months, the severity of cervical myelopathic syndrome also significantly decreased (p = 0.009). The neurological status of 18 (64.2 %) respondents improved in the first 3  months after corpectomy and anterior stabilization with titanium mesh implants and 6 months after the surgery, the status improved in the remaining 8 (30.7 %) patients (p˂0.001). Preoperative values of the Cobb sagittal angle allowed us to conclude the following. In 13 (46.4 %) patients, the normolordotic axis of the cervical spine was noted, in 12  (42.8  %) – the  hypolordotic axis, and in 3 (10.8 %) respondents, the Cobb angle values corresponded to the kyphotic axis of the cervical spine.

Conclusion. The technique of corpectomy and anterior fixation with mesh titanium implants in patients with myelopathic syndrome against the background of  degenerative diseases of the cervical spine makes it possible to improve the clinical status of the latter already 3 months after the operation was performed while maintaining normal biomechanical parameters of the cervical spine and complete decompression of the neural structures and supply their vessels.