Biomechanical changes of the cervical spine in internal fixation with different anterior cervical interbody fusion systems / 中国组织工程研究

BACKGROUND:Due to the treatment of cervical spondylosis,the Zero-P system of the anterior cervical interbody fusion system will have problems such as screw loosening and fracture after operation,so a novel Low-P system has been developed. OBJECTIVE:To compare the effects of the novel Low-P and Zero-P anterior cervical intervertebral fusion systems on the biomechanical properties of adjacent segments of the cervical spine and to perform stress analysis on the internal fixation system,so as to provide a theoretical reference for clinical treatment. METHODS:A complete model of the C1-C7 segment of the cervical spine was established.Based on the effectiveness of the model,a finite element model of Low-P(type Z Low-P and type H Low-P)and Zero-P system implanted in C4-C5 segments was established.The stress distribution of implanted devices and adjacent vertebral nucleus pulposus,fibrous rings and end plates was analyzed under the conditions of forward flexion,posterior extension,lateral bending and rotation. RESULTS AND CONCLUSION:(1)After implantation of Low-P and Zero-P internal fixation devices,the range of motion of the type H Low-P system was large;the maximum stress value of type Z Low-P system was small;the maximum stress of Zero-P on the nucleus pulposus of adjacent segments was large;the maximum stress of end plate was small.(2)The influence of three internal fixation systems on adjacent segment fiber rings was close.(3)The screw stress of the Zero-P internal fixation system was much greater than that of the Low-P system.(4)It is indicated that compared with Zero-P type internal fixation system,the novel Low-P system reduces the stress value of steel plate and screw,which can reduce screw loosening and internal fixation system failure.The Low-P system has less stress on the nucleus pulposus of adjacent discs and reduces disc degeneration in adjacent segments.This paper provides a theoretical basis for the clinical study of a Low-P type internal fixation system.

Effect of different fusion devices on cervical sagittal parameters after anterior cervical discectomy and fusion for cervical spondylotic myelopathy / 中国组织工程研究

BACKGROUND:The impact of anterior cervical surgery on the sagittal balance parameters of the cervical spine is gradually being paid attention to.Currently,there is a lack of clear and feasible clinical guidelines for the selection of surgical methods for two-level cervical spondylosis,aiming to find the most suitable fixation method that is more beneficial for this type of patient. OBJECTIVE:To compare the effects of different fusion devices for anterior cervical decompression on the changes of cervical sagittal parameters after surgery for adjacent two-level cervical spondylotic myelopathy. METHODS:A total of 44 patients with adjacent two-level cervical spondylotic myelopathy underwent anterior cervical discectomy and fusion from March 2018 to September 2020 in Liaocheng People's Hospital were retrospectively analyzed in the study,and they were divided into zero-p group(23 cases)and cage group(21 cases).All patients underwent anteroposterior X-ray,three-dimensional CT reconstruction and MRI examination before operation.At the last follow-up,the anteroposterior X-ray films of cervical spine were taken.The sagittal balance parameters of the cervical spine were measured before and after surgery,including cervical lordotic angle(C2-7 Cobb),C2-C7 sagittal vertical axis,segmented lordotic angle and T1 slope.The surgical time,intraoperative bleeding,last follow-up intervertebral fusion,and postoperative swallowing disorders were recorded,and Japanese Orthopaedic Association score on the patient was evaluated before and after surgery.The changes in cervical sagittal parameters before and after surgery were calculated and their differences were compared between the two groups. RESULTS AND CONCLUSION:(1)Both groups of patients successfully completed the surgery and received follow-up.The zero-p group had shorter surgical time and less intraoperative bleeding compared to the cage group,but the difference was not statistically significant(P>0.05).(2)The incidence rate of postoperative swallowing disorders in the cage group(7/21,33%)was higher than that in the zero-p group(3/23,13%),and the difference was statistically significant(P<0.05).(3)At the last follow-up,the clinical efficacy of the two groups was the same;all patients had bone fusion.Comparison within the group showed that the sagittal parameters of the cervical spine in both groups improved compared to before surgery(P<0.05).There was no statistically significant difference in sagittal parameters between groups(P>0.05),and there was no statistically significant difference in changes in C2-C7 sagittal vertical axis,C2-7 Cobb angle,and T1 slope between the two groups(P>0.05).However,the segmented lordotic angle changes in the zero-p group were smaller than those in the cage group,and the difference was statistically significant(P<0.05).(4)It is indicated that the use of zero-p and titanium plate combined with cage during anterior cervical discectomy and fusion surgery can effectively improve cervical sagittal balance.Titanium plate combined with cage intervertebral fusion can better reconstruct the patient's cervical lordosis and curvature.The selection of fusion devices should also comprehensively consider the occurrence of surgical complications.

Review of Zero-Profile anterior cervical interbody fusion cage in treatment of cervical degenerative diseases / 医疗卫生装备

The biomechanical stability of Zero-Profile anterior cervical interbody fusion cage(Zero-P)was introduced when used for anterior cervical discectomy and fusion(ACDF),and the efficacy of Zero-P was reviewed for treating cervical dege-nerative diseases such as single-and two-segment,intersegmental and multisegmental spondylotic cervical spondylolisthesis.The advantages of Zero-P were described in reducing the incidence rates of postoperative dysphagia and adjacent segment degeneration,and the disadvantages and countermeasures were put forward.References were provided for enhancing the efficacy of Zero-P for treating cervical degenerative diseases.[Chinese Medical Equipment Journal,2023,44(9):103-109]

Comparison between anterior cervical discectomy and fusion using zero-P and traditional anterior cervical plate plus cage for treating two-level cervical spondylosis / 中国组织工程研究

BACKGROUND: Anterior cervical discectomy and fusion is a classic surgical procedure for the treatment of cervical spondylosis. At present, we can use a Zero-P interbody fusion fixture and a traditional cervical anterior plate plus cage as an internal fixation material. The Zero-P has less postoperative esophageal interference and lower incidence of postoperative dysphagia compared with traditional anterior cervical plate fixation. Besides, the Zero-P could avoid the risk of excessively long or pooriy placed plate injury to adjacent segmental intervertebral discs. OBJECTIVE: To compare the safety and effectiveness between two-level anterior cervical discectomy and fusion using Zero-P and using traditional anterior cervical plate plus cage. METHODS: Clinical data of sixty patients who underwent two-level anterior cervical discectomy and fusion in the Chengdu Third People’s Hospital from May 2016 to May 2018 were retrospectively analyzed. The patients were divided into Zero-P group (Zero-P fusion, n=30) and plate group (anterior cervical plate fixation combined with cage implantation, n=30). All patients in the two groups had informed consent to the treatment plan. This study was approved by the hospital ethics committee. The Japanese orthopedic association score, neck disability index score and Bazaz swallowing function score were used to evaluate the clinical efficacy. Cervical X-ray and cervical CT scans were performed to assess cervical curvature, observe bone graft fusion, and implant displacement, loosening and breakage. RESULTS AND CONCLUSION: (1) All surgeries were successfully completed in 60 patients. The wounds healed in stage I after operation. There were no serious complications such as nerve injury, esophageal fistula, and cerebrospinal fluid leakage. (2) During the follow-up, there was no significant difference in neck disability index, Japanese orthopedic association score and bone graft fusion rates between the two groups (P > 0.05). (3) The incidence and severity of dysphagia in the Zero-P group were lower than those in the plate group at various time points after operation (all P < 0.05). (4) The overall curvature and operative segments curvature were better in the plate group than in the Zero-P group 6 months after surgery and in final follow-up (P < 0.05). (5) Two-level anterior cervical discectomy and fusion using Zero-P is a safe and effective operative method. The operation time, bleeding volume, number of fluoroscopy and postoperative dysphagia incidence were better than the traditional anterior cervical plate plus cage fixation system, but it is not as good as the traditional anterior cervical plate plus cage system in the curvature of the cervical spine. Zero-P is not recommended for patients with obvious abnormal cervical curvature before operation.

Comparison of prevertebral soft tissue swelling and dysphagia between Zero-p and traditional cage and titanium plate for anterior cervical discectomy with fusion / 局解手术学杂志

Objective To explore the relationship among the prevertebral soft tissue swelling and dysphagia rate after anterior cervical diskectomy and fusion(ACDF),and to investigate the prevertebral soft tissue swelling and dysphagia rate after Zero-p or traditionaI cage and titanium plate for one-level lesion of cervical myelopathy.Methods The clinical data of 54 patients with one-level lesion (C5/6) of cervical myelopathy who undelwent anterior cenrical discectomy and fusion by Zero-p (n =25) or traditional cage and titanium plate (n =29) were analyzed.The postoperative prevertebral soft tissue swelling was measured by lateral radiographs.Patients were divided into the swelling group (n =24) and the non-swelling group(n =30) based on the degree of prevertebral soft tissue swelling and the incidences of dysphagia were analyzed.Patients were divided into the Zero-p group (n =25)and the Cage group (n =29) based on surgical treatment,the postoperative prevertebral soft tissue swelling and dysphagia rate were compared.Results The rate of dysphagia in swelling group was 45.8％,which was higher than 13.3％ in non-swelling group,the difference was significant(P ＜0.05).The postoperative prevertebral soft tissue swelling was 6.22 mm averagely after Zreo-p,which was less than that after traditional cage and titanium plate for anterior cervical discectomy with fusion(9.25 mm),the difference was significant (P ＜ 0.05).The incidence of dysphagia in Zero-p group was 12％,which was lower than 41.4％ in Cage group,and the difference was statistically significant (P ＜ 0.05).Conclusion It is a clinical significance to evaluate the degree of prevertebral soft tissue swelling by cervical lateral X-ray after ACDF,when the degree of prevertebral soft tissue swelling is greater,the incidence of complications such as dysphagia is higher.In addition,The Zero-p for the treatment of single one-level lesion of cervical myelopathy(C5/6) has a lower degree of prevertebral soft tissue swelling and dysphagia rate than the traditional Cage and titanium plate fusion.

Research progress of anterior cervical interbody fusion system Zero-P in patients with cervical spondylosis / 中国现代医生

ACDF is a classical operation for the treatment of cervical spondylosis. Applying anterior cervical titanium plate during operation is with significant advantages. However, researches including long-term follow-up found there were many complications of the application of anterior cervical titanium plate, especially in the long-segment ACDF. To solve the problems of anterior cervical titanium plate application, a new kind of zero-profile anterior cervical inter-body fusion system appeared. Since Zero -P anterior cervical interbody fusion system began to be applied in clinical treatment, there were many studies on single/double -segment ACDF. The safety and effectiveness of this system has been confirmed by massive researches. The method of operation on the cervical spondylosis of 3/4 segment is still controversial. It has been a hot issue to treat cervical spondylosis of 3/4 segment using ACDF with the application of Zero-P. However, the safety and effectiveness of clinical application of this method have not reached a consensus and remain controversial.

Anterior Cervical Fusion Using a Zero-Profile Stand-Alone Cage: Radiological and Clinical Outcomes after More than 2 Years of Follow-Up

STUDY DESIGN: Retrospective analysis. OBJECTIVES: To analyze the usefulness of Zero-P® by analyzing the radiological and clinical outcomes with a minimum of 2 years of follow-up. SUMMARY OF LITERATURE REVIEW: Anterior discectomy and fusion (ACDF) using Zero-P® showed excellent results. However, there is a lack of studies focusing on long-term outcomes. MATERIALS AND METHODS: Ninety-eight patients who underwent single-level ACDF using Zero-P® with more than 2 years of follow-up were included for analysis. In the radiological analysis, we evaluated disc height, segmental lordosis, and subsidence in the preoperative, postoperative, and last follow-up periods. The Neck Disability Index (NDI), Neck Visual Analogue Scale (VAS), and Arm VAS were also evaluated for clinical assessment. Radiological bony fusion was assessed, and radiological and clinical differences according to bony fusion were evaluated. RESULTS: Intervertebral disc height had increased 2.92 mm after surgery and subsided to 2.36 mm at the final follow-up. Subsidence of the screw was 0.58 mm at final follow-up. Segmental lordosis was 3.97° at the preoperative assessment, 8.39° in the postoperative follow-up, and 5.83° in the last follow-up. The Neck VAS score was 4.47, 2.28, and 1.27, respectively. The Arm VAS score was 5.73, 3.13, and 2.18; and NDI score was 17.8, 11.7, and 7.89, respectively. There was no association between the radiological and clinical results. Radiological nonunion was found in 18 subjects. There were no significant differences in radiological and clinical parameters according to bony union. CONCLUSIONS: ACDF with Zero-P® for treatment of degenerative cervical disease showed subsidence in 55.1% and nonunion in 18% of cases. However, the radiological results were not related to the clinical results.