Cervical sagittal balance: a predictor of neck pain after anterior cervical spine surgery?

Cervical Sagittal Balance: Impact on Clinical Outcomes and Subsidence in Anterior Cervical Discectomy and Fusion

Degenerative disease of the cervical spine leads to sagittal imbalance, which may affect treatment results. The purpose of this study was to evaluate changes in selected cervical sagittal balance parameters and their effects on subsidence and clinical outcomes of the procedure. This study encompassed a total of 95 evaluated patients who underwent anterior cervical discectomy and fusion (ACDF). Selected cervical sagittal balance parameters were assessed using lateral projection X-rays: C2-C7 spinal vertical axis (C2-C7 SVA), spinocranial angle (SCA), C7 slope, C2-C7 lordosis, and the segmental Cobb angle. Measurements were collected the day before, the day after, and 12 months after surgery. Changes in clinical parameters was assessed using the VAS and NDI scales. Subsidence was defined as a loss of intervertebral height of more than 30% of the baseline value. Among all the assessed parameters, only the C2-C7 SVA demonstrated a statistically significant difference between the groups with and without subsidence: 26.03 vs. 21.79 [mm], with p = 0.0182, preoperatively and 27.80 vs. 24.94 [mm], with p = 0.0449, on the day after surgery, respectively. We conclude that higher preoperative and postoperative C2-C7 SVA values might contribute to an elevated risk of implant subsidence. Furthermore, both the SCA and C7 slope could conceivably influence the clinical outcome, respectively impacting pain, as assessed by the VAS and the disability, as evaluated through the NDI scale.

Retrospective Analysis of Sagittal Balance Parameters and Clinical Efficacy After Short-Segment Anterior Cervical Spine Surgery with Different Fusion Devices

Objective

To compare the cervical sagittal balance parameters and clinical efficacy of three fusion devices after short-segment anterior cervical discectomy and fusion.

Patients and Methods

Retrospectively analyzed 516 patients with cervical spondylosis who underwent surgery at our hospital from May 2013 to May 2019. All patients had complete data and were divided into three groups according to the selected fusion cage. Neck and upper limb pain were assessed by the visual analog scale (VAS) score. Neurological function was evaluated by the modified Japanese Orthopedics Society (mJOA) score. Also, the curvature of the cervical spine and the occurrence of dysphagia were observed.

Results

There were no significant differences in the general information, thoracic inlet angle, T1 slope, or surgical data among the groups (p>0.05). There were significant differences in the scores between pre- and postoperatively in the different groups (p<0.05). There were no significant differences in the C2-C7 Cobb angle or C2-C7 sagittal vertebral axis before the operation among the groups (p>0.05). There was a significant difference in the correction and loss of correction among the groups postoperatively and on follow-up (p>0.05). Dysphagia was less likely in the Zero-P VA fusion group than in the other two groups.

Conclusion

Different fusion instruments can relieve the symptoms. In the Prodisc-C Vivo group, no significant improvement in cervical sagittal balance was achieved. A good effect on improving sagittal balance was observed in both the Zero-P VA fusion and Skyline anterior cervical titanium plate groups, but a better effect on preventing dysphagia was observed in the Zero-PVA fusion group.