Is it possible to evaluate the parameters of cervical sagittal alignment on cervical computed tomographic scans?

MRI to measure cervical sagittal parameters: a comparison with plain radiographs

INTRODUCTION

The inability to visualize the sternum tip and T1 vertebra on radiographs may decrease the accuracy of the measurements of cervical sagittal parameters. The object of this study is to investigate the value of MRI to measure cervical sagittal parameters and to compare the data of cervical sagittal parameters on radiographs and MR images.

MATERIALS AND METHODS

Fifty-two asymptomatic adults were recruited. Each subject had both an MRI and radiographs of the cervical spine. Data, including C2-7 lordosis (CL), T1 slope (T1S), thoracic inlet angle (TIA), neck tilt (NT), and T1S minus C2-7 lordosis (T1S-CL), on radiographs and MRI were collected and analyzed.

RESULTS

There were significant differences in CL, T1S, and T1S-CL, between X-ray and MR imaging, but not in TIA and NT. Each of the radiographic cervical sagittal parameters had a significant relationship with the corresponding value on MRI, and the correlation between radiographic and MRI measurement of TIA was the most significant of all parameters.

CONCLUSIONS

Positional change may significantly influence most sagittal parameters. Supine MRI cannot substitute for upright cervical radiographs to measure most cervical sagittal parameters except for TIA in an asymptomatic population.

Emergency radiology: straightening of the cervical spine in MDCT after trauma--a sign of injury or normal variant?

OBJECTIVE

To evaluate whether straightening of the cervical spine (C-spine) alignment after trauma can be considered a significant multidetector CT (MDCT) finding.

METHODS

160 consecutive patients after C-spine trauma admitted to a Level 1 trauma centre received MDCT according to Canadian Cervical Spine Rule and National Emergency X-Radiography Utilization Study indication rule; subgroups with and without cervical collar immobilization (CCI +/-) were compared with a control group (n = 20) of non-traumatized patients. Two independent readers evaluated retrospectively the alignment, determined the absolute rotational angle of the posterior surface of C2 and C7 (ARA C2-7) and grouped the results for lordosis (<-13°), straight (-13 to +6°) and kyphosis (>+6°).

RESULTS

In the two CCI-/CCI+ study groups, the straight or kyphotic alignment significantly (p = 0.001) predominated over lordosis. The number of patients with straight C-spine alignment was higher in the CCI+ group (CCI+ 69% vs CCI- 49%, p = 0.05). A comparison of the CCI+ group vs the CCI- group revealed a slightly smaller number of kyphotic (10% vs 18%, p = 0.34) and lordotic (21% vs 33%, p = 0.33) alignments. Statistically, however, the differences were of no significance. The control group revealed no significant differences.

CONCLUSION

Straightening of the C-spine alone is not a definitive sign of injury but is a biomechanical variation due to CCI and neck positioning during MDCT or active patient control.

ADVANCES IN KNOWLEDGE

Straightening of the C-spine alignment in MDCT alone is not a definitive sign of injury. Straightening of the C-spine alignment is related to neck positioning and active patient control. CCI has a straightening effect on the cervical alignment.

Relationship between T1 slope and loss of lordosis after laminoplasty in patients with cervical ossification of the posterior longitudinal ligament

BACKGROUND CONTEXT

Laminoplasty is a major surgical method used to treat patients with cervical ossification of the posterior longitudinal ligament (OPLL). Sometimes, patients with cervical OPLL demonstrate postoperative kyphosis despite sufficient preoperative lordosis. Recently, the impact of T1 slope has emerged as a predictor of kyphotic alignment change after laminoplasty. However, the relationship between T1 slope and postoperative cervical alignment change is not yet fully established.

PURPOSE

The goals of the present study were to investigate the relationship between T1 slope and loss of cervical lordosis (LCL), and to identify the role of T1 slope as a predictor of postoperative kyphosis after laminoplasty in patients with OPLL.

STUDY DESIGN

This is a retrospective case study.

PATIENT SAMPLE

Between January 2011 and January 2012, 64 consecutive patients who underwent cervical laminoplasty for OPLL were enrolled (male:female ratio=47:17; mean age=55.9 years). Cervical spine lateral radiographs in neutral, flexion, and extension were taken before surgery and at 2-year follow-up.

OUTCOME MEASURES

The C2-C7 Cobb angle, cervical range of motion (ROM), T1 slope, neck tilt, and C2-C7 sagittal vertical axis (SVA) were measured from lateral radiographs of the cervical spine preoperatively and postoperatively at 2-year follow-up.

METHODS

Patients were divided into two groups according to preoperative T1 slope, and the postoperative cervical alignment change was compared between the groups. Postoperative kyphosis and LCL incidence were also evaluated at 2-year follow-up. The relationships between postoperative cervical alignment change and preoperative variables, including age, T1 slope, cervical ROM, C2-C7 SVA, and T1 slope minus C2-C7 Cobb angle (T1S-CL), were investigated.

RESULTS

Patients were divided into two groups above and below median preoperative T1 slope (23.2°). There were no differences in age, sex, type of OPLL, or operation level between the two groups. Patients with higher preoperative T1 slope demonstrated significantly more lordotic preoperative cervical alignment (p=.001). Patients with higher preoperative T1 slope were more likely to exhibit postoperative LCL (p=.03), and when it occurred the degree of LCL was greater (p=.06). In multiple linear regression analysis, higher T1 slope (B=0.414, p=.04) and lower T1S-CL (B=-0.412, p=.03) were significantly associated with more postoperative LCL. In spite of these results, postoperative kyphosis did not occur more frequently in patients with higher T1 slope (p=.64).

CONCLUSIONS

Patients with higher T1 slope had more lordotic curvature before surgery and demonstrated more LCL at 2-year follow-up. Cervical alignment was compromised after laminoplasty, and the degree of LCL was correlated with preoperative T1 slope. After laminoplasty for cervical OPLL, patients with higher T1 slope tended to exhibit a greater LCL yet did not drift into frank postoperative kyphosis.

Influence of T1 Slope on the Cervical Sagittal Balance in Degenerative Cervical Spine: An Analysis Using Kinematic MRI

STUDY DESIGN

A retrospective kinematic magnetic resonance imaging (kMRI) study.

OBJECTIVE

To evaluate the utility of kMRI in determining the relationship between cervical sagittal balance and TI alignment.

SUMMARY OF BACKGROUND DATA

Thoracic inlet parameters play an important role in cervical spine sagittal balance. However, most of the literature is based on lower resolution cervical X-rays or CT scans in the supine position.

METHODS

Cervical spine kMRI of 83 patients with degenerative cervical spine conditions (20-68 yr of age) was analyzed for: (1) cervical spine parameters: C2-C7 angle, C2-C7 sagittal vertical axis (SVA), cranial tilt, and cervical tilt; and (2) T1 parameters: thoracic inlet angle (TIA), T1 slope, and neck tilt (NT). Multiple logistic regression analysis and Pearson correlation coefficients were performed.

RESULTS

The mean TIA, T1 slope, and NT were 78.0, 33.2, and 44.8°, respectively. The mean C2-7 angle, SVA of C2-C7, cervical tilt, and cranial tilt were -15.4°, 22.0 mm, 18.1°, and 15.1°, respectively. The ratio of cervical:cranial tilt was maintained as 55:45%. A significant correlation was found between the C2-C7 angle and T1 slope (r = 0.731), TIA and C2-C7 angle (r = 0.406), cervical tilt with C2-C7 angle (r = 0.671), T1 slope with TIA (r = 0.429), TIA with neck tilt (r = 0.733), TIA with cervical tilt (r = 0.377), SVA C2-C7 with cervical tilt (r = -0.480), SVA C2-C7 with cranial tilt (r = 0.912), and C2-7 SVA with the ratio of cranial tilt to cervical tilt (r = 0.694).

CONCLUSION

An individual with a large T1 slope required large cervical lordosis to preserve physiologic sagittal balance of the cervical spine. Cranial tilt was the cervical parameter most strongly correlated with SVA C2-C7, and thus may be a good parameter to assess decompensation of cervical sagittal balance.

LEVEL OF EVIDENCE

3.

The Effect of the Pedicle-Facet Angle on Degenerative Cervical Spondylolisthesis

Objective

To measure the orientation of the facet joints of cervical spine (C-spine) segments in the sagittal plane, known as the pedicle-facet (P-F) angle, and to use these measurements to evaluate the relationship between the P-F angle and the amount of vertebral anterolisthesis in patients with degenerative cervical spondylolisthesis (DCS).

Methods

A retrospective case-control study was performed including 30 age- and sex-matched patients with DCS and 30 control participants. Anterior-posterior and lateral view radiographs of the C-spine were obtained in a standing position. The P-F angle at all cervical levels and the amount of anterolisthesis at C4-5 were measured from lateral view plain radiographs.

Results

The P-F angles at C4-5 were 141.14±7.14° for the DCS group and 130.53±13.50° (p=0.012) for the control group, and at C5-6 were 137.46±8.53° for the DCS group and 128.53±16.01° for the control group (p=0.001). The mean P-F angle at C4-5 did not correlate with the amount of anterolisthesis (p=0.483). The amount of anterior slippage did correlate with age (p<0.001).

Conclusion

The P-F angle was intrinsically higher at C4-5, compared to C5-6, in both the DCS and control groups, which might explain the increased likelihood for anterolisthesis of C4. Higher P-F angles in the DCS group may be a predisposing factor to slippage. The P-F angle may interact with age to increase incidence of anterolisthesis with increasing age.

Analysis of Cervical Sagittal Balance Parameters in MRIs of Patients with Disc-Degenerative Disease

Background

The aim of this study was to explore the correlations between the different parameters of the cervical sagittal balance in magnetic resonance images (MRI) and evaluate the criteria for their clinical application in disc-degenerative diseases.

Material/Methods

We conducted a retrospective review of the MRIs of 125 adult outpatients with disc-degenerative diseases of the cervical spine; the images were obtained between May and July 2014 at our institute. The control group comprised 50 volunteers whose MRIs were also obtained. The parameters measured in the MRIs were: neck tilt (NT), T1 slope (T1S), thoracic inlet angle (TIA), and Cobb’s angle (C2–7). The correlation between the various parameters was analyzed using the Pearson correlation coefficient.

Results

The outpatients group showed moderate correlation between TIA and T1S, a significant correlation between TIA and NT, a weak correlation between T1S and Cobb’s angle, and a weakly negative correlation between T1S and NT. Further, the TIA showed no significant difference between the outpatient group and the control group, as per the sample t test.

Conclusions

Our findings indicate that TIA, T1S, and NT could be used as indices for the evaluation of cervical sagittal balance and that the TIA could be used as a reference to assess the cervical compensation. Restoration of the NT and T1S should be considered as a goal of surgical treatment during the preoperative planning in patients with disc-degenerative diseases.

The Effect of Different Pillow Heights on the Parameters of Cervicothoracic Spine Segments

Objective

To investigate the effect of different pillow heights on the slope of the cervicothoracic spine segments.

Methods

A prospective analysis of data from 16 asymptomatic adults (aged 20 to 30 years) was carried out. Exclusion criteria were history of injury or accident to the cervicothoracic spine, cervicothoracic spine surgery, or treatment for neck symptoms. We used three different pillow heights: flat (0 cm), 10-cm, and 20-cm pillows. Cervical sagittal parameters, measured with radiography, included; C2-7 Cobb's angle, T1 slope (T1S), thoracic inlet angle (TIA), and neck tilt (NT). Statistical analyses were performed using Spearman correlation coefficients.

Results

As the height of the pillow increased, the T1S & C2-7 Cobb's angle increased while the NT values tended to decrease. The TIA values, however, remained constant. Additionally, there was a statistically significant sex difference in T1S with the 0-cm pillow (p=0.01), and in NT with the 20-cm pillow (p=0.01).

Conclusion

From the data obtained in this study, we recommend that the most suitable pillow height is 10 cm, considering the normal cervical lordosis.