In the treatment of cervical disc herniation, anterior cervical decompression-implant fusion can be used, and posterior decompression-implant fusion with single or double doors can also be used, and most authors use anterior decompression-implant fusion in anterior surgery, which can be divided into anterior cervical decompression-implant fusion with preserved endplates and without preserved endplates according to whether the endplates are preserved or not. After observation by some authors, it was found that there were some problems with anterior cervical implant fusion without preservation of the endplate, such as compensatory degeneration of the cervical spine in the adjacent segment, anterior collapse, small intervertebral foramen, reduction of the height of the fused segment and recurrence of symptoms, etc. A total of 102 cases of traumatic and degenerative cervical disc herniation were treated surgically with anterior cervical implant fusion with preservation of the endplate, and the previous anterior cervical implant fusion without preservation of the endplate. The average follow-up period was 2 years and 6 months, and the effect of both on the height of the fused segments was compared. 1. Clinical data 1.1 Cases There were 102 cases of traumatic and degenerative cervical disc herniation (group A), 79 males and 23 females, aged 13 to 67 years old, with an average age of 39.7 years, who were diagnosed and treated surgically by clinical examination, X-ray and/or MRI. There were 56 cases of traumatic cervical disc herniation and 46 cases of degenerative cervical disc herniation; 5 cases of cervical 2 and 3 disc herniation, 17 cases of cervical 3 and 4 disc herniation, 49 cases of cervical 4 and 5 disc herniation, 43 cases of cervical 5 and 6 disc herniation, 14 cases of cervical 6 and 7 disc herniation, and 6 cases of cervical 7 thoracic 1 disc herniation, including 24 cases of 2 intervertebral disc herniation and 4 cases of 3 intervertebral disc herniation. There were 4 cases of cervical disc herniation with 3 intervertebral spaces. The previously performed cervical fusion without preservation of the endplate was used as the control group (group B) in 78 cases. 1.2 Surgical method and postoperative treatment The endplate of the vertebral body was preserved in 102 cases, and the disc was removed to the posterior longitudinal ligament, the cartilage endplate was scraped, the bony endplate was scraped into a rough surface to the point of bleeding, and the autologous iliac bone block was implanted. Internal fixation was used or not. The postoperative treatment was conventional. For those with internal fixation, external fixation of the cervical perimeter was added after surgery, and for those without internal fixation, external fixation of the head, neck and chest cast was applied after surgery for 3 months. The surgical method of anterior cervical fusion without preservation of the vertebral endplate was as follows: a circular saw or an electric drill was used to make a bone groove in the corresponding vertebral space, and the remaining part of the vertebral endplate was bitten off to the vertebral cancellous bone, and an autologous iliac bone block was implanted, with or without internal fixation. The total number of cases in the two groups was 142 with internal fixation and 38 without internal fixation. The postoperative treatment was the same as in group A. There were no significant differences between the two groups in terms of gender, age, location, injury and severity, follow-up time, whether internal fixation was used or not, and the type of internal fixation. 1, 3 Observation methods Positive and lateral cervical radiographs were taken at 1 w, 3 months, 6 months, 1 year, 2 years, and 3 years after surgery to observe the morphology of the cervical spine. The height of the fused segment was measured by the Emery method, and a horizontal line was made below the upper vertebral body and above the lower vertebral body to determine the midpoint of the upper and lower endplates, and the vertical distance between the two points was the height of the fused segment. In group A, there were 19 cases of cervical degeneration in the non-fusion area, 17 cases of posterior collapse, and no anterior collapse of the fused segment; in group B, there were 23 cases of cervical degeneration in the non-fusion area, 19 cases of anterior collapse of the fused segment, and 7 cases of posterior collapse of the fused segment. The mean fusion segment height was not significantly different between group A at 3 months, 6 months, 1 year, 2 years and 3 years after surgery (P>0.05), and group B at 6 months, 1 year, 2 years and 3 years after surgery (P>0.05). The difference between the mean fused segment height and the postoperative fused segment height was significant in group B (P0.05, Table 2). Some authors have found that anterior cervical implant fusion without preservation of the endplate often has some problems, such as postoperative reduction of vertebral body height and fused segment height, adjacent disc herniation and recurrence of symptoms [2-4]. According to Yonenobu et al [4], anterior cervical implant fusion without preservation of the endplate often leads to increased motion load and stress concentration in the nonfused segment, most significantly in the adjacent segment, resulting in abnormal motion and instability of the adjacent segment, disc degeneration and herniation, and recurrence of symptoms. Xu Baoshan et al [2] followed up 107 patients with anterior cervical decompression graft fusion without preserving the endplate for more than 10 years and found that the fused segment showed obvious fusion angle, different degrees of anterior collapse of the vertebral body, and degenerative protrusion of the adjacent segment in 12 cases. Zhang Xia et al [5] reported that 76 cases of cervical spondylosis underwent anterior decompression and fusion with bone grafting, and 38 cases showed aggravation of cervical degeneration after surgery, and 4 cases had recurrence of cervical disc herniation. The anterior cervical decompression-implant fusion with preservation of the end plate can better maintain the height of the vertebral body and the fused segment, and anterior cervical fusion with preservation of the end plate has been carried out overseas. Preservation of the endplate is the basis for preserving the ideal biomechanical strength of autogenous interbody fusion. After preserving the endplate, the endplate as the recipient bed still has rich blood flow, and preserving the endplate does not affect the bone graft fusion. The mean fusion time was 3.9 months in the group with preserved endplates and 3.6 months in the group without preserved endplates, and there was no significant difference between the two (P>0.05). Therefore, cervical fusion with preserved endplates does not affect the quality of osseous fusion of the cervical spine, nor does it affect the time to fusion. The authors concluded that anterior cervical implant fusion with preservation of the end plate has the following advantages: (1) the operation is performed on the end plate cartilage without blood circulation, and intraoperative bleeding is significantly reduced; (2) the biomechanical properties of the cortical bone around the vertebral body are preserved, the end plate cortical bone has higher strength, and the cancellous bone of the vertebral body is less likely to collapse; (3) the height of the intervertebral foramen is maintained, and there is less deformation of the intervertebral foramen, which reduces the possibility of nerve root compression; (4) the bone graft is less likely to collapse into the vertebral body The bone graft is not easy to collapse into the vertebral body, and it can maintain the height of the intervertebral foramen because it has a continuous support effect on the intervertebral space. When the cases with and without internal fixation were analyzed together, it was found that there was no significant difference in the mean height of the fused segment between the group with and without internal fixation (P>0.05), suggesting that the use of internal fixation was not the main cause of the decrease in the height of the fused segment or the maintenance of the height of the fused segment. Of course, internal fixation is beneficial for maintaining cervical stability and promoting fusion. At follow-up, we found that the mean fusion segment height in the group without retained endplates differed significantly (P0.05) from 1 w postoperatively at all time points after 6 months of surgery. It was suggested that the loss of fusion segment height occurred mainly within 1 year after surgery, especially within 6 months after surgery, while after 1 year after surgery, the fusion segment height no longer decreased significantly with the completion of bony fusion and crawling replacement of the bone graft in the cervical spine. In the group with preserved endplates, there was no significant difference in fusion segment height at all postoperative time points (P>0.05), suggesting that anterior cervical bone graft fusion with preserved endplates can better maintain the vertebral body and fusion segment height. Therefore, the anterior cervical spine surgery, especially the anterior cervical spine graft fusion without preserved endplates, should be protected by appropriate braces for 3-6 months after surgery to prevent the loss of fused segment height after surgery. The authors speculated that the reasons for the gradual decrease of fusion segment height in the group without preserved endplates might be: (1) the destruction of the vertebral endplates and part of the cancellous bone during surgery, resulting in the decrease of fusion segment height; (2) the partial resorption of the bone graft after surgery; (3) the collapse of the bone graft into the vertebral body after surgery; and (4) the microfracture of the bone graft that was not completely crawled to replace the bone graft during weight bearing in some cases at an early stage of weight bearing. Therefore, in most cases, the reduction in fusion segment height occurs 6 months to 1 year after surgery. The stable structures of the spine, such as the anterior longitudinal ligament and sometimes the posterior longitudinal ligament, are also destroyed and the vertebral body is subjected to abnormal stresses, while there is a gap of about 5 mm behind the bone graft, so the area of the bone graft is smaller than the cross-sectional area of the upper and lower edges of the original vertebral body. Therefore, Jia Lianshun et al [6] emphasized that the height of the fused segment must be maintained during bone grafting or bone grafting with internal fixation, and the bone graft must be more than 2 mm larger than the gap distance to prevent the loss of anterior column height during bony healing. In this study, postoperative cervical degeneration and posterior osteophytes in the non-fused region occurred in both groups, and the more fused segments there were, the more complications there were. However, anterior collapse of the fused segment occurred in 19 cases in the group without preservation of the endplate, whereas no anterior collapse occurred in the group with preservation of the endplate, suggesting that preservation of the endplate can effectively prevent anterior collapse of the fused segment. Although the hydroxyapatite-coated artificial disc replacement can better preserve the function of the disc and maintain the height of the fused segment in animal experiments [8 ], and the artificial nucleus pulposus replacement made by Xu Yuliang et al. has also achieved good results, the design of the artificial disc is not perfect at present, and it is still in animal experiments or the initial clinical application stage, and its effect of replacing the function of the disc needs further study. Moreover, in many cases, cervical fusion is necessary for the stability of the cervical spine. Therefore, anterior cervical fusion with preservation of the endplate is a procedure that can better maintain the height of the vertebral body and the fused segment and prevent anterior collapse of the fused segment.