Relationship between TIA minus C0-7 angle and C2-7 SVA: analysis of 113 symptomatic patients

Comparison of sagittal measurements of cervical spine in spondylosis patients between Magnetic Resonance Imaging and Radiograph

Background

Cervical spondylosis is the common degenerative disease of the vertebrae in adults which can lead to change in sagittal alignment of cervical spine. Radiograph and Magnetic resonance imaging (MRI) are widely used imaging modalities for measuring the sagittal parameters. However sagittal parameters measured using radiograph and MRI can be influence by patient positioning and imaging technique. The study aims to compare sagittal parameters measured using MRI (Magnetic Resonance Imaging) and radiograph in cervical spondylosis patients.

Methods

The study was done retrospectively. 77 patients who underwent both MRI and radiograph were included in the study. The sagittal parameters such as Neck Tilt (NT), T1 slope (T1S), thoracic inlet angle (TIA), C2-C7 angle (C2-C7A) and C2-C7 sagittal vertical axis (C2-C7 SVA) were measured on sagittal MRI and lateral cervical spine radiograph. Paired t-test was used to compare cervical sagittal measurements between MRI and radiography.

Results

The cervical sagittal parameters such as NT, T1S, TIA and C2-7 SVA showed significant difference between MRI and radiograph (p < 0.05). But C2-C7A did not show significant difference (p > 0.05).

Conclusion

The study concludes that MRI cannot be used as an alternative to cervical spine radiograph in spondylosis patient for measuring the sagittal balance as there was significant difference between sagittal parameters except C2-C7 A.

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

PURPOSE

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).

METHODS

A total of 98 patients who underwent cervical laminoplasty without preoperative kyphotic alignment were included (mean age, 73.7 years; 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.

RESULTS

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.

CONCLUSION

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.

Relationship between C2 slope with sagittal parameters and clinical function of degenerative cervical kyphosis

PURPOSE

To explore the relationship between C2 slope with sagittal parameters and clinical function of degenerative cervical kyphosis (DCK).

METHODS

A retrospective analysis of 127 patients with degenerative cervical spondylosis treated in our spinal deformity center from January 2019 to June 2022. Patients were categorized into two groups and compared based on C2-7 angle (C2-7 ≥ 5° as kyphosis group, C2-7 < 5° as lordosis group). Pearson correlation or Spearman correlation was used to analyze the relationship between C2S and conventional radiological parameters and health -related quality-of-life (HRQOL) outcomes as measured by the EuroQol 5 dimension questionnaire (EQ5D), NRS, and the neck disability index (NDI). The cutoff value of C2S was determined by a receiver operating characteristic (ROC) curve.

RESULTS

There were 127 patients who met inclusion criteria (79 men and 48 women). Average 56.00 ± 10.27 years old (range 31-81 years old). C2S of kyphosis group is higher than non-kyphosis group. Aggravating cervical kyphosis increases cSVA positively. For all patients, C2S demonstrated a significant correlation with the O-C2 angle, C2-7 angle, cSVA, and TS-CL (p < 0.05). NRS, NDI and EQ5D-VAS scores revealed a significant correlation with C2S and cSVA (p < 0.01). For the subgroup of patients presenting with DCK, ROC curves demonstrated the cutoff values of C2S as 26.3°, and 30.5°, according to a cSVA of 40 mm, and severe disability expressed by NDI, respectively.

CONCLUSION

On the basis of retaining the consistency of cranio-cervical and cervico-thoracic structure, C2S can better analyze the sagittal alignment of DCK patients than TS-CL and has good practicability in clinical application and HRQOL evaluation.