Cervical Sagittal Parameters Research Articles

Could indirect decompression occur for cord compression by the ligamentum flavum with anterior cervical discectomy and fusion?

Cord compression by the ligamentum flavum (CCLF) has been reported to adversely affect the clinical outcomes of anterior cervical discectomy and fusion (ACDF). While indirect decompression does occur for foraminal stenosis with ACDF, whether ACDF could improve CCLF with the distraction of disc space remains unclear. This study aimed to identify 1) whether indirect decompression occurs for CCLF with ACDF, and 2) risk factors that hinder the improvement of CCLF. This retrospective cohort study included 119 patients who underwent ACDF for the treatment of cervical myelopathy and CCLF was detected on preoperative MRI. Patients who demonstrated improvement in CCLF grade after ACDF were included in the improved group, while those who did not show improvement were classified as the unimproved group. Patient characteristics, cervical sagittal parameters, neck and arm pain visual analog scale score, and Japanese Orthopaedic Association (JOA) score were assessed. A comparison between the improved and unimproved groups was performed. Regression analyses were performed to identify factors associated with CCLF grade improvement. Overall, 58.0% (69/119) of patients showed improvement in CCLF grade after ACDF. CCLF grade did not improve in the remaining 42.0% (50/119) of patients, and 3.4% (4/119) of patients experienced aggravation of CCLF after ACDF. Preoperative spondylolisthesis (OR 0.252, 95% CI 0.090-0.711; p = 0.009) and greater segmental lordosis 3 months postoperatively (OR 0.835, 95% CI 0.731-0.953; p = 0.008) were the factors that hindered the improvement of CCLF after ACDF. Furthermore, patients with higher pre- or postoperative CCLF grades showed significantly less improvement in JOA score 2 years postoperatively. Indirect decompression for CCLF with ACDF is not reliable because 42.0% of patients did not demonstrate improvement in CCLF grade after the operation. Preoperative spondylolisthesis and postoperative increased segmental lordosis were risk factors for failure of CCLF improvement. Both pre- and postoperative higher CCLF grades were associated with poor neurological recovery 2 years postoperatively.

Differences in cervical sagittal parameters and muscular function among subjects with different cervical spine alignments: a surface electromyography-based cross-sectional study.

We analyzed cervical sagittal parameters and muscular function in different cervical kyphosis types. This cross-sectional study enrolled subjects with cervical spine lordosis (cervical curvature < -4°) or degenerative cervical kyphosis (cervical curvature > 4°), including C-, S-, and R-type kyphosis. We recorded patients' general information (gender, age, body mass index), visual analog scale (VAS) scores, and the Neck Disability Index (NDI). Cervical sagittal parameters including C2-C7 Cobb angle (Cobb), T1 slope (T1S), C2-C7 sagittal vertical axis (SVA), spino-cranial angle (SCA), range of motion (ROM), and muscular function (flexion-relaxation ratio (FRR) and co-contraction ratio (CCR) of neck/shoulder muscles on surface electromyography). Differences in cervical sagittal parameters and muscular function in subjects with different cervical spine alignments, and correlations between VAS scores, NDI, cervical sagittal parameters, and muscular function indices were statistically analyzed. The FRR of the splenius capitis (SPL), upper trapezius (UTr), and sternocleidomastoid (SCM) were higher in subjects with cervical lordosis than in subjects with cervical kyphosis. FRRSPL was higher in subjects with C-type kyphosis than in subjects with R- and S-type kyphosis (P < 0.05), and was correlated with VAS scores, Cobb angle, T1S, and SVA. FRRUTr was correlated with NDI, SCA, T1S, and SVA. FRRSCM was correlated with VAS scores and Cobb angle. CCR was correlated with SCA and SVA. Cervical sagittal parameters differed among different cervical kyphosis types. FRRs and CCRs were significantly worse in R-type kyphosis than other kyphosis types. Cervical muscular functions were correlated with cervical sagittal parameters and morphological alignment.

Analysis of odontoid parameters in adolescent idiopathic scoliosis patients with different curve types.

Odontoid incidence (OI) is an important parameter that has recently been developed. However, there are currently no studies on OI in adolescent idiopathic scoliosis (AIS) patients. We aimed to examine the significance of OI in describing cervical sagittal alignment in AIS patients, explore the differences in cervical sagittal parameters among these patients with different curve types, and investigate the correlations between coronal deformity and cervical sagittal parameters in AIS patients. The whole-spine anteroposterior and lateral plain radiographs of AIS patients were retrospectively analyzed. The parameters, including OI, odontoid tilt (OT), C2 slope, cervical lordosis (CL), T1 slope (T1S), and others, were measured. The AIS patients were grouped based on different curve types. Measurement parameters were compared between different groups. Pearson correlation analysis was performed for cervical sagittal parameters and Cobb angle. Ninety AIS patients were included, consisting of 14 males and 76 females. The main thoracic curve group exhibited a smaller OI compared to the main thoracolumbar/lumbar curve group (P < 0.05). In the AIS patients with a main thoracic curve, there was a significant correlation between Cobb angle and OI (r = -0.371, p < 0.01). The odontoid parameters exhibited significant correlations with several classic cervical sagittal parameters in AIS patients with different curve types. The validation of the formula CL = 0.36 × OI-0.67 × OT-0.69 × T1S showed a significant correlation (correlation coefficient = 0.917) between the actual measurements and the predicted values, with a determination coefficient of 0.842. There may be a difference in OI between AIS patients with a main thoracic curve and those with a main thoracolumbar/lumbar curve. Odontoid parameters could be used to describe cervical sagittal alignment in AIS patients with different curve types.

Influence of cranium orientation on cervical sagittal alignment during radiographic examination: a radiographic analysis

BACKGROUND CONTEXTDuring the radiographic examination, the cranium orientation varies not only individually but also within the same subject, in different imaging sessions. Knowing how changes in the orientation of the cranium influences cervical sagittal alignment during the radiographic examination of the cervical spine can aid clinicians in the accurate evaluation for cervical sagittal alignment in clinical practice. PURPOSETo radiographically examine the influence of cranium orientation on cervical sagittal alignment during radiographic examination in an asymptomatic cohort. STUDY DESIGNA prospective radiographic study. PATIENT SAMPLEEighty asymptomatic volunteers (mean age, 40.4 years; 50.0% male) were enrolled. OUTCOME MEASURESCervical sagittal parameters including the regional slope (C1 slope, C2 slope, C5 slope, C7 slope, and T1 slope), Cobb angle (O–C1 angle, C1–C2 angle, C2–C5 angle, C5–C7 angle, and C7–T1 angle), and cranial/cervical offset (sella turcica tilt [ST tilt] and C2 tilt). METHODSIn all participants, standing lateral radiographs of the cervical spine were taken in three forward-gazing positions: anteverted-cranium (AC) position; neutral-cranium (NC) position; and retroverted-cranium (RC) position. Cervical sagittal parameters, including the regional slope, Cobb angle, and cranial/cervical offset, in these three positions were statistically compared. RESULTSThe C1 and C2 slopes were anteverted and retroverted in the AC and RC positions, respectively, compared to those in the NC position. The C5 slope, C7 slope, and T1 slope were constant among the three positions. In O–C2 and C2–C5, statistically significant differences in the regional Cobb angles were identified among the three positions; however, there were no significant differences in the C5–C7 or C7–T1 segments. Cranial and cervical offsets of ST tilt and C2 tilt increased and decreased when the cranium was anteverted and retroverted, respectively. CONCLUSIONSThe current study suggests that the adjustment of the cranium orientation when taking cervical spine radiographs is mainly controlled at the upper cervical spine of the O–C2 segment in an asymptomatic cohort. On radiograph, alignment in the upper cervical segment of O–C2 changes; accordingly, the middle cervical segment of C2–C5 can change during the adjustment of cranium orientation. However, alignment in the lower cervical segment of C5–C7 and the cervicothoracic junction of C7–T1 remains constant. Further, cranial/cervical offset increases and decreases when the cranium is anteverted and retroverted, respectively. Our results can help the accurate evaluation of cervical sagittal alignment on plain radiographs in clinical practice.

Does Spinal Cord-Canal Mismatch Adversely Affect the Clinical Outcomes of Anterior Cervical Discectomy and Fusion for the Treatment of Cervical Myelopathy?

Retrospective cohort study. To clarify whether clinical outcomes of anterior cervical discectomy and fusion (ACDF), is affected by presence of spinal canal-cord mismatch (SCCM). SCCM is considered a factor that would moderately influence surgeons to perform posterior surgery since it could widen the spinal canal, while an anterior approach could only remove degenerative pathologies grown into the spinal canal. We retrospectively reviewed 186 patients who underwent ACDF and had been followed-up for >2 years. Patients with spinal cord occupation ratio (SCOR) of ≥0.7 were classified into the SCCM group, while those with a SCOR of <0.7 were included in the no-SCCM group. Patient demographics, cervical sagittal parameters, neck pain visual analog scale (VAS), arm pain VAS, and Japanese Orthopedic Association (JOA) score were assessed. JOA score was the primary outcome of the study. One-hundred and forty-seven patients (79.0%) were included into the no-SCCM group, while 39 patients (21.0%) were classified into the SCCM group. Postoperative radiographic parameters including C2-C7 lordosis, C2-C7 sagittal vertical axis, and range of motion did not significantly differ between the two groups. Neck pain VAS, arm pain VAS, and JOA score (no-SCCM group, from 13.7±2.5 to 14.6±2.3, P<0.001; SCCM group, from 13.8±1.6 to 15.0±2.0, P<0.001) significantly improved after the operation in both groups, and results were not significantly different between the two groups. Furthermore, SCOR was not significantly associated with JOA recovery rate at 2 years postoperatively in linear regression analysis. Clinical and radiographic outcomes of ACDF were not affected by the presence of SCCM. Furthermore, SCOR was not significantly associated with neurologic recovery at 2 years of follow-up. Therefore, ACDF can be safely and effectively applied for treating cervical myelopathy, regardless of the presence of SCCM, when other factors favor the anterior approach. 3.

Is cervical sagittal alignment associated with pain and disability in myofascial pain syndrome?: A cross-sectional study

ObjectiveTo elucidate the role of cervical sagittal alignment in the pathophysiology of cervical myofascial pain syndrome(MFPS) and its impact on pain levels and disability status among patients. MethodsThis prospective cross-sectional study included participants aged 18–64 years experiencing neck pain for more than 3 months and diagnosed with MFPS. Cervical sagittal parameters (C0–2 cervical lordosis(CL) angle, C2–7 CL angle, cervical sagittal vertical axis (cSVA), T1 slope, T1 slope minus CL mismatch(T1S-CL), and cervical tilt) were measured using Surgimap software by an expert physiatrist. Pain levels were assessed using the Numerical Pain Rating Scale(NRS), and neck disability was evaluated using the Neck Bournemouth Questionnaire(NBQ). ResultsOut of 200 initially assessed participants with cervical MFPS, 133 were included after excluding ineligible individuals. The mean age of the participants was 35.3±8.2 years. Participants categorized by pain severity (moderate vs. severe) showed no significant differences in cervical range of motion, C0–2 angle, cSVA, T1 slope and T1S-CL. However, significant differences were observed in C2–7 angle (p=0.008), cervical tilt (p=0.006), and NBQ scores (p<0.001) between the two pain severity groups. Grouping based on T1S-CL compliance showed no significant differences in pain and disability effects. Correlation analysis revealed weak negative correlations between pain levels and C2–7 Cobb angle (p=0.009, r=0.226) as well as cervical tilt (p=0.005, r=0.243). No correlations were found between cervical sagittal parameters and NBQ scores. ConclusionsDecreased C2–7 CL angle and cervical tilt angle are associated with increased pain levels; however, cervical sagittal alignment was not found to be associated with disability.

Variation of Odontoid Incidence According to Age in Asymptomatic Children

To investigate the effect of age and sex on odontoid parameters and their relationships with cervical sagittal alignment in children. A total of 155 Chinese children without cervical symptoms were divided into groups by age: 3-12years (87 participants), 13-18years (68 participants), and sex: male (91 participants) and female (64 participants). Lateral plain radiographs of the whole spine were analyzed for (1) odontoid parameters: odontoid incidence (OI), odontoid tilt, and C2 slope (C2S); and (2) cervical sagittal parameters: C0-2, C2-3, C2-4, C2-5, C2-6, and C2-7 angles (cervical lordosis [CL]), T1 slope (T1S), and T1S minus CL (T1S-CL). Student's t-tests, linear regression analyses, and Pearson's correlation coefficient analyses were performed. OI showed a significant difference between the 3-12 and 13-18year groups (13.35°±4.32° vs. 17.21°±4.26°, P<0.001), and significant differences were also observed in odontoid tilt (P=0.001) and C2S (P<0.001) between different sexes. Positive correlations were found between age and OI in the 3-12 and 13-18year groups (adjusted R2=0.104 and 0.048, respectively). OI and C2S were positively correlated with the C0-2 angle in all age and sex groups. Age emerged as a critical determinant of OI, which increased with age among pediatric populations. Clinicians should carefully consider the disparity in OI during the assessment and restoration of cervical sagittal balance in children.

Analysis of imaging characteristics and effectiveness of cervical spondylotic myelopathy with cervical kyphosis

To investigate the imaging characteristics of cervical kyphosis and spinal cord compression in cervical spondylotic myelopathy (CSM) with cervical kyphosis and the influence on effectiveness. The clinical data of 36 patients with single-segment CSM with cervical kyphosis who were admitted between January 2020 and December 2022 and met the selection criteria were retrospectively analyzed. The patients were divided into 3 groups according to the positional relationship between the kyphosis focal on cervical spine X-ray film and the spinal cord compression point on MRI: the same group (group A, 20 cases, both points were in the same position), the adjacent group (group B, 10 cases, both points were located adjacent to each other), and the separated group (group C, 6 cases, both points were located >1 vertebra away from each other). There was no significant difference between groups ( P>0.05) in baseline data such as gender, age, body mass index, lesion segment, disease duration, and preoperative C 2-7 angle, C 2-7 sagittal vertical axis (C 2-7 SVA), C 7 slope (C 7S), kyphotic Cobb angle, fusion segment height, and Japanese Orthopedic Association (JOA) score. The patients underwent single-segment anterior cervical discectomy with fusion (ACDF). The occurrence of postoperative complications was recorded; preoperatively and at last follow-up, the patients' neurological function was evaluated using the JOA score, and the sagittal parameters (C 2-7 angle, C 2-7 SVA, C 7S, kyphotic Cobb angle, and height of the fused segments) were measured on cervical spine X-ray films and MRI and the correction rate of the cervical kyphosis was calculated; the correlation between changes in cervical sagittal parameters before and after operation and the JOA score improvement rate was analyzed using Pearson correlation analysis. In 36 patients, only 1 case of dysphagia occurred in group A, and the dysphagia symptoms disappeared at 3 days after operation, and the remaining patients had no surgery-related complications during the hospitalization. All patients were followed up 12-42 months, with a mean of 20.1 months; the difference in follow-up time between the groups was not significant ( P>0.05). At last follow-up, all the imaging indicators and JOA scores of patients in the 3 groups were significantly improved when compared with preoperative ones ( P<0.05). The correction rate of cervical kyphosis in group A was significantly better than that in group C, and the improvement rate of JOA score was significantly better than that in groups B and C, all showing significant differences ( P<0.05), and there was no significant difference between the other groups ( P>0.05). The correlation analysis showed that the improvement rate of JOA score was negatively correlated with C 2-7 angle and kyphotic Cobb angle at last follow-up ( r=-0.424, P=0.010; r=-0.573, P<0.001), and positively correlated with the C 7S and correction rate of cervical kyphosis at last follow-up ( r=0.336, P=0.045; r=0.587, P<0.001), and no correlation with the remaining indicators ( P>0.05). There are three main positional relationships between the cervical kyphosis focal and the spinal cord compression point on imaging, and they have different impacts on the effectiveness and sagittal parameters after ACDF, and those with the same position cervical kyphosis focal and spinal cord compression point have the best improvement in effectiveness and sagittal parameters.

Comparison of radiological and clinical outcomes of cervical laminoplasty versus lateral mass screw fixation in patients with ossification of the posterior longitudinal ligament

PurposeThis study aimed to compare cervical sagittal parameters and clinical outcomes between patients undergoing cervical laminoplasty(CL) and those undergoing lateral mass screw fixation(LMS).MethodsWe retrospectively studied 67 patients with multilevel ossification of the posterior longitudinal ligament (OPLL) of the cervical spine who underwent lateral mass screw fixation (LMS = 36) and cervical laminoplasty (CL = 31). We analyzed cervical sagittal parameters (C2-7 sagittal vertical axis (C2-7 SVA), C0-2 Cobb angle, C2-7 Cobb angle, C7 slope (C7s), T1 slope (T1s), and spino-cranial angle (SCA)) and clinical outcomes (visual analog scale [VAS], neck disability index [NDI], Japanese Orthopaedic Association [JOA] scores, recovery rate (RR), and minimum clinically significant difference [MCID]). The cervical sagittal parameters at the last follow-up were analyzed by binary logistic regression. Finally, we analyzed the correlation between the cervical sagittal parameters and each clinical outcome at the last follow-up after surgery in both groups.ResultsAt the follow-up after posterior decompression in both groups, the mean values of C2-C7 SVA, C7s, and T1s in the LMS group were more significant than those in the CL group (P ≤ 0.05). Compared with the preoperative period, C2-C7 SVA, T1s, and SCA gradually increased, and the C2-C7 Cobb angle gradually decreased after surgery (P < 0.05). The improvement in the JOA score and the recovery rate was similar between the two groups, while the improvement in the VAS-N score and NDI score was more significant in the CL group (P = 0.001; P = 0.043). More patients reached MCID in the CL group than in the LMS group (P = 0.036). Binary logistic regression analysis showed that SCA was independently associated with whether patients reached MCID at NDI postoperatively. SCA was positively correlated with cervical NDI and negatively correlated with cervical JOA score at postoperative follow-up in both groups (P < 0.05); C2-7 Cobb angle was negatively correlated with cervical JOA score at postoperative follow-up (P < 0.05).ConclusionCL may be superior to LMS in treating cervical spondylotic myelopathy caused by OPLL. In addition, smaller cervical SCA after posterior decompression may suggest better postoperative outcomes.

Comparative Analysis of Postoperative Sagittal Balance in Expansive Open-Door Laminoplasty versus Laminectomy with Fusion for Multilevel Ossification of Posterior Longitudinal Ligament: A Retrospective Study.

BACKGROUND This single-center study included 80 patients with multilevel cervical ossification of the posterior longitudinal ligament (OPLL) and aimed to compare postoperative sagittal balance following treatment with expansive open-door laminoplasty (LP) vs total laminectomy with fusion (LF). MATERIAL AND METHODS Data of 80 patients with multilevel OPLL treated with LP vs LF between January 2017 and January 2022 were retrospectively analyzed. The basic data, cervical sagittal parameters, and clinical outcomes of the patients were counted in the preoperative and postoperative periods, and complications were recorded. Forty patients underwent LP and 40 underwent LF. Cervical sagittal parameters were compared between and within the 2 groups. Clinical outcomes and complications were compared between the 2 groups. RESULTS At last follow-up, the postoperative C2-C7 Cobb angel, T1 slope (T1S), and C7 slope (C7S) were significantly higher in the LF group than in the LP group (P<0.001). C2-C7 SVA (cSVA) was slightly higher in the LF group (P>0.05) and significantly higher in the LP group (P<0.05). The incidence of postoperative complications in the LP group was significantly lower than in the LF group (P=0.02). The postoperative scores on the Visual Analog Scale (VAS), Neck Disability Index (NDI), and Japanese Orthopedic Association (JOA) were significantly improved in both groups (P<0.001). CONCLUSIONS Both procedures had good outcomes in neurological improvement. After posterior surgery, the cervical vertebrae all showed a tilting forward. Compared to LP, LF may change cervical balance in Cobb angel, T1S. LF has better efficacy in improving cervical lordosis compared with LP. Patients with high T1 slope after surgery may has more axial pain.

Sagittal balance parameters measurement on cervical spine MR images based on superpixel segmentation.

Introduction: Magnetic Resonance Imaging (MRI) is essential in diagnosing cervical spondylosis, providing detailed visualization of osseous and soft tissue structures in the cervical spine. However, manual measurements hinder the assessment of cervical spine sagittal balance, leading to time-consuming and error-prone processes. This study presents the Pyramid DBSCAN Simple Linear Iterative Cluster (PDB-SLIC), an automated segmentation algorithm for vertebral bodies in T2-weighted MR images, aiming to streamline sagittal balance assessment for spinal surgeons. Method: PDB-SLIC combines the SLIC superpixel segmentation algorithm with DBSCAN clustering and underwent rigorous testing using an extensive dataset of T2-weighted mid-sagittal MR images from 4,258 patients across ten hospitals in China. The efficacy of PDB-SLIC was compared against other algorithms and networks in terms of superpixel segmentation quality and vertebral body segmentation accuracy. Validation included a comparative analysis of manual and automated measurements of cervical sagittal parameters and scrutiny of PDB-SLIC's measurement stability across diverse hospital settings and MR scanning machines. Result: PDB-SLIC outperforms other algorithms in vertebral body segmentation quality, with high accuracy, recall, and Jaccard index. Minimal error deviation was observed compared to manual measurements, with correlation coefficients exceeding 95%. PDB-SLIC demonstrated commendable performance in processing cervical spine T2-weighted MR images from various hospital settings, MRI machines, and patient demographics. Discussion: The PDB-SLIC algorithm emerges as an accurate, objective, and efficient tool for evaluating cervical spine sagittal balance, providing valuable assistance to spinal surgeons in preoperative assessment, surgical strategy formulation, and prognostic inference. Additionally, it facilitates comprehensive measurement of sagittal balance parameters across diverse patient cohorts, contributing to the establishment of normative standards for cervical spine MR imaging.

A Novel Cervical Sagittal Classification for Asymptomatic Population Based on Cluster Analysis.

Cross-sectional study. To propose a novel cervical sagittal classification for asymptomatic people so as to deepen the understanding of cervical sagittal alignment. Cervical spine sagittal morphology varies in people. There is a lack of widely-accepted cervical sagittal classification method. In all, 183 asymptomatic subjects were included. A series of global and segmental cervical sagittal parameters were measured. Subjects with cervical lordosis (CL)<0 degrees were incorporated directly into the kyphosis (K) group. For subjects with CL ≥0 degrees, a two-step cluster analysis was used to arrive at the optimal number of clusters. The results of the expressions for the subtypes were derived by graphing. The 60 randomly selected lateral cervical spine films were evaluated by 4 spine surgeons at 4-week intervals using our classification method, the Toyama classification method and the Donk classification method. The 3 classification methods' reliability was expressed by the intra-group correlation coefficient (ICC), and convenience was expressed by the measuring time. Finally, the distribution of 4 subtypes was depicted, and sagittal parameters were compared among subtypes. Four subtypes of the cervical spine were suggested: Large lordosis (LL): CL≥-1.5×T1 slope (TS)+70°; Small lordosis (SL): -1.5×TS+50°≤CL<-1.5×TS+70°; Straight (S): 0°≤CL<-1.5×TS+50°; and K: CL<0°. The measuring time for our classification method was significantly less than the Toyama classification method (P<0.001). Our classification method showed high inter-observer reliability (ICC=0.856) and high to excellent intra-observer reliability (ICC between 0.851 and 0.913). SL was the most common type (37.7%). Men had more LL type and women had more S type and K type. The proportion of S and K increased with age. Cervical sagittal parameters were significantly different among the subtypes except for C4 vertebral body (VB) angle (P=0.546), C2-C7 SVA (P=0.628) and NT (P=0.816). We proposed a novel cervical sagittal classification for an asymptomatic population, which proved to be simple to implement with satisfactory reliability.

Cervical Sagittal Alignment and Related Factor Analysis and Prediction Model in Patients Undergoing Revision Surgery After Anterior Cervical Fusion.

Patients with myelopathy or radiculopathy commonly undergo anterior cervical fusion surgery (ACFS), which has a notable failure rate on occasion. The goal of this study was to compare revision and nonrevision surgery patients in cervical sagittal alignment (CSA) subsequent to ACFS; additionally, to identify the best CSA parameters for predicting clinical outcome after ACFS; and furthermore, to create an equation model to assist surgeons in making decisions on patients undergoing ACFS. The data of 99 patients with symptomatic cervical myelopathy/radiculopathy who underwent ACFS were analyzed. Patients were divided into group A (underwent revision surgery after the first surgery failed) and group B (underwent only the first surgery). We measured and analyzed both preoperative and postoperative CSA parameters, including C2 slope, T1 slope, cervical lordosis C2-C7 (CL), C2-C7 sagittal vertical axis (C2C7 SVA), occiput-C2 lordosis angle (C0-C2), and chin brow vertical angle, and we further computed the correlation between the CSA parameters and created a prediction model. The (T1S-CL)-C2S mismatch differed significantly between groups A and B ([9.95 ± 9.95] 0 , [3.79 ± 6.58] 0 , P < 0.05, respectively). A significant correlation was observed between C2 slope and T1CL in group B relative to group A postoperatively (R 2 = 0.42 versus R 2 = 0.09, respectively). Compared with group B, patients in group A had significantly higher C2C7SVA values, more levels of fusion, and more smokers. The sensitivity, specificity, accuracy, and discrimination of the model were, respectively, 73.5%, 84%, 78.8%, and 85.65%. The causes of revision surgery in cervical myelopathic patients after anterior cervical corpectomy and fusion/anterior cervical diskectomy and fusion are multifactorial. (T1S-CL)-C2S mismatch and high C2C7SVA are the best cervical sagittal parameters that increase the odds of revision surgery, and the effect is more enhanced when comorbidities such as smoking, low bone-mineral density, and increased levels of fusion are taken into account.

Analyzing results of cervical sagittal parameters in patients operated with polyetheretherketone cages without plate.

This was a retrospective longitudinal observational study. The purpose of this study was to analyze the results of cervical sagittal parameters on preoperative and postoperative lateral radiographs in anterior cervical discectomy and fusion (ACDF). ACDF is believed to change craniocervical parameters and thus cervical curvature using polyetheretherketone (PEEK) or titanium cages with or without self-locking as well as an anterior plate, the latter of which has not been shown to provide better clinical or radiological results. Cervical spondylotic myelopathy (CSM) is a common degenerative pathology that can affect one or more levels and treatment has varied over time trying to maintain sagittal parameters within acceptable values where the ACDF is the main treatment. The study was performed in patients with CSM who underwent anterior cervical discectomy, and their pre- and postoperative radiographs were analyzed using Surgimap software a few days before and 3 months after surgery. Fifteen files were included in the study. Statistically significant sagittal balance variables were observed in cervical lordosis (CL) with an increase of 4.73° (P = 0.019) and T1 slope (T1S)-CL with a decrease of -5.93° (P = 0.007). CL and T1S-CL showed favorably modified values when performing ACDF using stand-alone PEEK cages without the need for self-blocking or an anterior plate.

Cervical sagittal parameters in degenerative cervical spondylolisthesis versus degenerative cervical kyphosis with myeloradiculopathy treated by anterior cervical discectomy and fusion.

Adult spinal deformity, especially sagittal imbalance, is affecting health-related quality-of-life (HRQOL) scores. There is a lack of emphasis in the comparison of cervical sagittal parameters in patients with degenerative cervical spondylolisthesis and degenerative cervical kyphosis. The aim of study is to determine the preoperative and postoperative cervical sagittal parameters in myeloradiculopathic patients with degenerative cervical spondylolisthesis and degenerative cervical kyphosis treated by anterior cervical discectomy and fusion (ACDF). A retrospective medical records and radiographic study of 30 adult patients were reviewed. Fifteen patients with degenerative cervical spondylolisthesis and 15 patients with degenerative cervical kyphosis have been performed ACDF from 2010-2020. We measured the preoperative and postoperative cervical sagittal parameters: C0-C2 angle, C1-C2 angle, C2-C7 angle, C2-C7 sagittal vertical axis (SVA), T1 slope, neck tilt angle and thoracic inlet angle. Minimum follow-up period was at least 2 years. Patients in degenerative cervical kyphosis group have C2-C7 angle less than degenerative cervical spondylolisthesis group (-14.88±7.32 vs. 9.60±13.60), leading to increase the mismatch between T1 slope and C2-C7 angle in kyphotic group and hyperlordosis of C0-C2 angle and C1-C2 angle (31.13±7.68, 37.88±5.08) compare with spondylolisthesis group (13±10.20, 24.60±10.70). Whereas patients with degenerative cervical spondylolisthesis have C2-C7 SVA (33.22±13.92) more than kyphosis group (13.70±13.60). After surgery, there is significant increase of the C2-C7 angle in the kyphosis group compare before and after surgery (-14.88±7.32 vs. 4.10±11.80). While the spondylolisthesis group has no significantly different parameters compare to before surgery. However, the postoperative cervical sagittal parameters of all patients are within the normal thresholds (T1-Slope minus C2-C7 lordosis <15° and C2-C7 SVA <40 mm). The study demonstrates the difference of sagittal parameters between degenerative cervical spondylolisthesis and kyphosis before and after surgery. ACDF not only provides neural decompressive procedure, but also corrects the regional cervical sagittal parameters.

The association of cervical sagittal alignment with anterior bone loss following single-level anterior cervical surgery.

Anterior bone loss (ABL) is a common phenomenon after cervical disc replacement (CDR), which can also be observed after anterior cervical discectomy and fusion (ACDF). This study aimed to investigate the incidence and severity of ABL in single-level CDR and ACDF and explore the association of cervical sagittal alignment with ABL. This is a single-center retrospective cohort study. A total of 113 patients treated with CDR and 99 patients treated with ACDF were retrospectively reviewed from January 2014 to December 2018 in West China Hospital. Radiological data were collected at pre-operation, 1 week, 3 months postoperatively, and the last follow-up. The incidence and severity of ABL after both CDR and ACDF were evaluated. Cervical sagittal alignment parameters, including C0-C2 angle, cervical lordosis (CL), C2-C7 sagittal vertical axis (cSVA), T1 slope, functional spinal unit angle, disc angle, and surgical level slope, were evaluated. ABL was identified in 75 (66.4%) patients in the CDR group and 57 (57.6%) patients in the ACDF group. There were no significant differences in the incidence, severity, and location of ABL between the ACDF and CDR groups. For patients who underwent ACDF, the proportion of females was significantly higher in the ABL group (64.9% vs. 33.3%, P=0.002), whereas the body mass index (BMI) was significantly lower in the ABL group compared to the non-ABL group (22.72±3.09 vs. 24.60±3.04, P=0.002). No effect of ABL on the short-term clinical outcomes of ACDF and CDR was observed. In the ACDF group, patients with ABL had significantly smaller postoperative CL (11.83°±8.24° vs. 15.25°±8.32°, P=0.04) and cSVA (17.77±10.08 vs. 23.35±9.86 mm, P=0.007). In the CDR group, no significant differences were found in the cervical sagittal parameters between patients with and without ABL (CL: 12.58±8.70 vs. 15.46±8.50, P=0.10; cSVA: 20.95±8.54 vs. 19.40±9.43, P=0.38). ABL is common after both CDR and ACDF with comparable incidence and severity. Cervical sagittal alignment was closely related to ABL after ACDF yet had less influence on ABL after CDR.

Odontoid incidence: a constant cervical anatomical feature evident in standing plain radiographs and supine magnetic resonance images

ObjectiveTo assess whether there is a difference between measurements of odontoid incidence (OI) and other cervical sagittal parameters by X-ray radiography and those by supine magnetic resonance imaging (MRI).MethodsStanding X-ray and supine MRI images of 42 healthy subjects were retrospectively analyzed. Surgimap software was employed to measure cervical sagittal parameters including OI, odontoid tilt (OT), C2 slope (C2S), C0-2 angle, C2-7 angle, T1 slope (T1S) and T1S-cervical lordosis (CL). Paired samples t-test was applied to determine the difference between parameters measured by standing X-ray and those by supine MRI. In addition, the statistical correlation between the parameters were compared. The prediction of CL was performed and validated using the formula CL = 0.36 × OI − 0.67 × OT − 0.69 × T1S.ResultsSignificant correlations and differences were found between cervical sagittal parameters determined by X-ray and those by MRI. OI was verified to be a constant anatomic parameter and the formula CL = 0.36 × OI − 0.67 × OT − 0.69 × T1S can be used to predict CL in cervical sagittal parameters.ConclusionsOI is verified as a constant anatomic parameter, demonstrating the necessity of a combined assessment of cervical sagittal balance by using standing X-ray and supine MRI. The formula CL = 0.36 × OI − 0.67 × OT − 0.69 × T1S can be applied to predict CL in cervical sagittal parameters.

C4 constant vertebra: a novel benchmark of physiological cervical sagittal alignment.

Cervical sagittal alignment is essential, and there is considerable debate as to what constitutes physiological sagittal alignment. The purpose of this study was to identify constant parameters for characterizing cervical sagittal alignment under physiological conditions. A cross-sectional study was conducted in which asymptomatic subjects were recruited to undergo lateral cervical spine radiographs. Each subject was classified according to three authoritative cervical sagittal morphology classifications, followed by the evaluation of variations in radiological parameters across morphotypes. Moreover, the correlations among cervical sagittal parameters, age, and cervicothoracic junction parameters were also investigated. A total of 183 asymptomatic Chinese subjects were enrolled with a mean age of 48.4 years. Subjects with various cervical sagittal morphologies had comparable C4 endplate slope angles under all three different typing systems. Among patients of different ages, C2-C4 endplate slope angles remained constant. Regarding the cervicothoracic junction parameters, T1 slope and thoracic inlet angle affected cervical sagittal parameters, including cervical lordosis and C2-7 sagittal vertical axis, and were correlated with the endplate slope angles of C5 and below and did not affect the endplate slope angles of C4 and above. In general, the slope of the C4 inferior endplate ranges between 13° and 15° under different physiological conditions. In the asymptomatic population, the C4 vertebral body maintains a constant slope angle under physiological conditions. The novel concept of C4 as a constant vertebra would provide a vital benchmark for diagnosing pathological sagittal alignment abnormalities and planning the surgical reconstruction of cervical lordosis.

Usefulness of the preoperative thoracic inlet angle in comparison to the T1 slope for predicting cervical kyphosis after laminoplasty.

Thoracic inlet angle (TIA) is a sagittal radiographic parameter with a constant value regardless of posture and is significantly correlated with the sagittal balance of the cervical spine. However, the practical use of TIA has not been studied. This study aimed to investigate the usefulness of the preoperative TIA for predicting the development of kyphotic deformity after cervical laminoplasty in comparison to the preoperative T1 slope (T1S). A total of 98 patients who underwent cervical laminoplasty without preoperative kyphotic alignment were included (mean age, 73.7years; 41.8% female). Radiography was evaluated before surgery and at the 2-year follow-up examination. The cervical sagittal parameters were measured on standing radiographs, and the TIA was measured on T2-weighted MRI in a supine position. Cervical alignment with a C2-C7 angle of ≥ 0° was defined as lordosis, and that with an angle of < 0° was defined as kyphosis. Postoperative kyphosis occurred in 11 patients (11.2%). Preoperatively, the kyphosis group showed significantly lower values in the T1S (23.5° vs. 30.3°, p = 0.034) and TIA (76.1° vs. 81.8°, p = 0.042). We performed ROC curve analysis to clarify the impact of the preoperative TIA and T1S on kyphotic deformity after laminoplasty. The optimal cutoff angles for TIA and T1S were 68° and 19°, respectively, with similar diagnostic accuracy. This study demonstrated the clinical utility of the preoperative TIA for predicting the risk of postoperative kyphotic deformity after cervical laminoplasty. These findings suggest the importance of the preoperative assessment of thoracic inlet alignment in cervical spine surgery.

Upper and lower cervical alignment parameters measured on supine magnetic resonance imaging with the occipital slope as a key marker of cervical alignment.

Cervical spine alignment is evaluated by measuring the cervical angles or parameters on standing plain radiography. In this study, we aimed to evaluate mainly the upper cervical alignment and the correlation between upper and lower cervical sagittal parameters measured on supine magnetic resonance imaging (MRI). Cervical MRIs of 210 outpatients were reviewed to measure the upper and lower cervical sagittal parameters. Their mean values were compared with normative values measured on standing X-ray from the literature. Correlations between the parameters were analyzed using the Pearson's correlation coefficient. The C0 slope was correlated with all other parameters, except for the C2-7 sagittal vertical axis. The strongest correlations (r > 0.500) were between the CL and C2 slope, between the CO2 and C0 slope, and between the C2 slope and C0 slope. On supine MRI, the C0 slope is a key marker of cervical spinal alignment. A strong correlation was observed between the C2 slope and C0 slope; therefore, the relationship between upper and lower cervical alignment could be assessed using slopes on MRI.