Comparison Of Sagittal Parameters Between Single-segment Zero-P Spacer And Titanium Plate Combined With Cage Fixation

Objectives: Sagittal alignment comparison between zero-profile spacer(Zero-P)and plate with cage in the treatment of single level cervical spondylosis.Methods: Clinical data from 45 patients with single level cervical spondylosis who underwent anterior cervical discectomy and fusion by zero-profile implant(Zero-P,group A,n=23)or titanium plate with cage(group B,n=24)from January 2015 to June 2017 were analyzed retrospectively.The mean follow-up for group A was 17.08±7.94 months,and 17.36±8.73 months for group B.Overall sagittal alignment(C2-C7 Cobb angle?T1 slope?Neck tilt?Thoracic inlet angle?Cervical tilt?Cranial tilt?C2-C7 SVA),treatment-level sagittal alignment(Functional Spinal Unit angle?Disc Angle?Anterior vertebral body Spacing?Posterior vertebral body Spacing),The Japanese Orthopaedic Association(JOA)scoring and JOA recovery rate,The Neck disability index(NDI),The Bazaz dysphagia grading before and after the operation and at the last follow-up were compared and analyzed.Results:(1)There were no statistically significant differences in the global sagittal parameters between the two groups at each time point and between the two groups.(2)There were no significant differences between the two groups in the preoperative and postoperative DA,the FSU angle and spacing between the anterior and posterior vertebral bodies at each time point.The DA at the last follow-up in group A was significantly smaller than that in group B(P=0.012).(3)In group A,DA at the final follow-up was less than before and after surgery(P<0.05).Postoperative AS and PS were both higher than pre-operation(P <0.05).However,at the last follow-up,AS and PS were decreased compared with those after surgery(P <0.05),and the reduction of AS was greater than that of PS.In group B,there was no statistically significant difference between DA at each time point.Postoperative AS and PS increased compared with preoperative,but AS and PS also decreased at the final follow-up(P <0.05),AS decreased slightly compared with PS,AS and PS lost less than Group A.(4)A positive correlation was found between DA and AS in both groups.(5)The JOA scores at the last follow-up in the two groups were significantly higher than before the operation(P<0.01).JOA scores at the same time point and the JOA recovery rate at the last follow-up were not statistically significant differences.Conclusion:(1)Both zero-profile spacer and titanium plate combined with cage can achieve good clinical efficacy for single-level cervical spondylosis.However,neither of them will have a significant effect on the overall cervical sagittal balance and the FSU angle of the treated segment.(2)Both surgical methods can significantly increase the anterior and posterior vertebral body spacing in the treatment segment after surgery.The zero-p group was less than the plate with cage group for the maintenance of intervertebral space.(3)Zero-P has advantages in reducing postoperative swallowing difficulties in patients compared with the titanium plate group.(4)Plate with cage group is superior to Zero-P group in maintaining the local lordosis angle.For patients with local kyphosis before the operation,plate with cage surgery seems to be a better choice.