As our population ages and the number of office workers increases rapidly, the number of patients with cervical spondylosis is also increasing year by year. Since the introduction of anterior cervical surgery by Smith Robinson and Cloward in the 1950s, the scope of surgical treatment for cervical spondylosis, surgical techniques, and surgical modalities have evolved, and the popularity of surgery has become increasingly widespread. At the same time, a series of problems brought about by surgical treatment have become increasingly prominent. In recent years, with the development of evidence medicine, the understanding of issues such as the grasp of the indications for cervical spondylosis surgery, the improvement of surgical principles and the management of postoperative complications has gradually advanced. I. Indications for surgery for cervical spondylosis Not all patients with cervical spondylosis require surgery or are suitable for surgery. Patients with spinal cord cervical spondylosis and neurogenic cervical spondylosis who have been ineffective after more than 3 months of regular conservative treatment or who have recurrent episodes of conservative treatment with uniform clinical symptoms, signs and imaging (CT or MRI) have clear indications for surgery; the timing of surgery should be before irreversible damage occurs to the spinal cord compression, which is the key to improving the efficacy of surgery; however, for patients who have been treated conservatively for 4 to 6 weeks, some scholars have suggested that surgery should be performed for patients with rapidly developing disease. However, for patients with rapidly developing disease after 4 to 6 weeks of conservative treatment, some scholars believe that surgical intervention should also be performed; patients with rapidly deteriorating neurological and diaphoretic dysfunction should be operated as early as possible. The understanding of vertebral artery cervical spondylosis is widely divergent. The indications and effects of surgical treatment are still controversial. For cervical instability with horizontal displacement ≥ 3 mm or angular displacement ≥ 11 ° or more, anterior cervical fusion is feasible if accompanied by symptoms of vertebral artery ischemia; for clear osteophytes of the hook vertebral joint compressing the vertebral artery causing symptoms of vertebral artery ischemia, lateral anterior decompression can be selected at the discretion of the patient. The basic principles of surgical treatment of cervical spondylosis are decompression of the spinal cord and neural tissue, restoration of the physiological curvature and intervertebral height of the cervical spine, and stabilization of the diseased segment (bone graft fusion or fixation). 1.Decompression: The pressure-causing factors of cervical spondylosis include “soft” tissues such as protruding intervertebral disc, hyperplastic yellow ligament or posterior longitudinal ligament, and “hard” tissues such as hyperplastic bony flab, ossified yellow ligament and posterior longitudinal ligament. In terms of relieving pressure on the spinal cord and nerve roots, direct decompression should be more desirable; however, indirect decompression is feasible for those who have extensive pressure-causing factors or whose compression is too severe for direct decompression. Decompression should be as complete as possible, but complete decompression is not the same as extensive decompression and should take into account the stability of the cervical spine. The expansion of intervertebral foramen volume and the expansion of vertebral canal volume resulting from the restoration of vertebral canal sequence also belong to the scope of indirect decompression. 2.Osseointegration: Although there are reports on the use of artificial discs after anterior cervical decompression to preserve intervertebral mobility, the clinical observation period is still short. Osseointegration as a guarantee of long-term stability of the cervical spine is still the standard procedure. Autologous three-sided cortical-iliac bone graft is the gold standard for anterior cervical implant fusion. In recent years, several different types of artificial bone have been used in clinical practice. A mixture of osteoinductive factors, mainly BMP, and autologous bone has been gradually used clinically and experience is beginning to be gained; osseous fusion can be obtained with block calcium phosphate ceramics alone, but clinical cases are still rare. Allogeneic bone graft has been gradually used less and less because of its fusion rate and antigenicity. 3.Fixation In order to obtain immediate postoperative stability for early mobility, internal fixation after decompression of the bone graft is beneficial; internal fixation also helps to maintain the physiological curvature and intervertebral height of the cervical spine and prevent complications such as collapse of the bone graft. With internal fixation, complications such as dislodgement and collapse of the bone graft have been reduced from 7-8% to 2-3%. Internal fixation for cervical spondylosis is also divided into anterior and posterior fixation. The anterior fixation system includes anterior cervical plate, anterior cervical Cage and artificial disc. The anterior cervical plate system with locking plate has a single cortical screw fixation technique, which greatly increases the safety of operation. The anterior cervical plate should be pre-bent to accommodate the physiological curvature of the corrected cervical spine; the screws should avoid penetrating the endplate or screwing into the intervertebral space. The anterior cervical screw-in Cage is easy to operate and has immediate postoperative stability, but the destruction of the endplate can cause collapse of the distal vertebral segment, and Cage dislodgement and slippage can occur. The embedded Cage can effectively prevent collapse of the vertebral segment by preserving the endplate and is an option for single-segment or non-adjacent gap decompression. Artificial discs are effective in preserving interbody mobility in the cervical spine, but further clinical experience is needed. Posterior fixation may be considered for posterior cervical laminectomy of three or more vertebrae. The posterior lateral block screw technique has strong biomechanical stability and can meet the needs of general posterior cervical fixation patients, but care should be taken to avoid damage to the vertebral artery and nerve roots during operation. The pedicle screw technique has better biomechanical stability than the lateral block screw technique, but the operation technique is more demanding. 4. Restoration of cervical physiological curvature and intervertebral height The idea of restoring cervical physiological curvature and intervertebral space height has received increasing attention from scholars since we proposed it. The restoration of intervertebral space height and physiological curvature is the basis for maintaining normal cervical spine biomechanical properties, and the expansion of intervertebral foramina volume after restoration of intervertebral space height has obvious clinical significance for indirect decompression of nerve roots; restoration of cervical spine physiological curvature can restore the spinal canal volume, which can also achieve the purpose of indirect decompression. Intraoperative use of interbody spacers is beneficial to the restoration of cervical physiological curvature and intervertebral height. While cervical spine surgery is widely carried out, there are still many problems in the surgical treatment of cervical spine due to the lack of strict grasp of the principles of cervical spine surgery and the inadequacy of technology and conditions, some of which may even bring serious consequences to patients. 1, incomplete decompression or excessive decompression: decompression is the key to good results, the principle of decompression is to completely remove the compressor but should preserve the structure of the vertebral joint itself as much as possible. In the case of combined posterior vertebral body bone superfluity and ossification of the posterior longitudinal ligament, it is often difficult to completely remove the compressive factors; failure to remove the hyperplastic posterior longitudinal ligament due to technical reasons can also lead to incomplete decompression; if the nucleus pulposus tissue is free below the posterior longitudinal ligament, failure to perform posterior longitudinal ligament resection may result in residual nucleus pulposus tissue. Therefore, a complete decompression should include the removal of the bony flab, degenerated or herniated discs and posterior longitudinal ligament tissue of the diseased segment. In addition, posterior cervical decompression can result in secondary compression if the lamina is not removed enough or the sharp edges of the lamina are not removed at the upper and lower poles of the decompression zone. On the contrary, some single-segment lesions should be decompressed with a single interval, but a subtotal resection of the vertebral body due to the operator’s lack of experience increases the trauma on the one hand, and increases the potential risk of degeneration of adjacent segments due to the increase of fused segments on the other hand. (1) Collapse and dislodgement of bone graft: Whether using autologous iliac bone or Cage or titanium mesh bone graft, due to improper trimming of bone graft or poor postoperative fixation, collapse and dislodgement of bone graft, withdrawal of Cage or slippage of titanium mesh can occur to different degrees. (2) Pseudarthrosis: Although the rate of pseudarthrosis after anterior implant fusion has decreased significantly with the development of internal fixation techniques such as plate, there are still 2-10% of patients with bone nonunion due to screw loosening, plate fracture, or their own osteoporosis. Screws screwed into the implant-body interface or the intervertebral space are also a cause of postoperative pseudarthrosis, which can be avoided by intraoperative fluoroscopy and should be given adequate attention by the operator. The rate of pseudarthrosis formation is higher in long segment fusion than in short segment fusion. (3) Restoration of the physiological curvature and intervertebral height of the cervical spine: the current problems in this area are mainly due to the lack of attention by the operator, resulting in the physiological curvature not being corrected or the intervertebral height not being restored. The use of Caspar spacers is effective in restoring disc height and cervical physiological curvature, and the design of threaded Cages with anterior diameter greater than posterior diameter, such as CHTF and Interfix, is useful in restoring cervical curvature, but long-term Cage subsidence may result in loss of vertebral segment height. Embedded Cages such as the SynCage-C have a tendency to replace threaded Cages gradually because they preserve the integrity of the vertebral endplate and reduce the postoperative Cage subsidence rate. However, due to improper use of spacers, postoperative neck and shoulder pain caused by over-spreading of the vertebral segments or decreased stability caused by over-distraction of the posterior vertebral structures may occur in some cases, which should be given sufficient attention by clinicians. (4) Fixation: The current problems in the use of internal fixation in the cervical spine are relatively serious. The problem of misuse of internal fixation has not been given enough attention and effectively controlled. As Prof. Dick said, the relationship between orthopedic surgeons and internal fixation has become closer and closer in the past 20 years, but at the same time, the treatment effect of patients has not been significantly improved. The indications for internal fixation are not strictly controlled: for example, blind surgery and internal fixation for those with mild clinical symptoms and no conservative treatment in the early stage of cervical spondylosis, or those with only imaging but no clinical symptoms; additional internal fixation for lesions in adjacent segments with two or more Cages, small hemivertebral laminectomy or total laminectomy in posterior decompression, and no obvious effect on cervical stability, etc. etc. ② Excessive use of internal fixation: anterior cervical Cage has been designed to meet the requirements of immediate postoperative stability, but some foreign scholars apply Cage with additional plate fixation, and no external fixation after surgery, this move should be based on a good health insurance system and the urgency of patients to return to work, it is difficult to carry out widely in China, too many implants also increase the economic burden of patients; some cases In some cases, solid bony fusion has been obtained after anterior surgery, and internal fixation is generally not necessary for posterior surgery again. (3) Blind or over-reliance on internal fixation: the most critical thing in the surgical treatment of cervical spondylosis is decompression, and the use of internal fixation is only an auxiliary means to meet early activity and provide conditions for bone graft fusion. The failure to remove or completely remove the pressure-causing factors is the primary factor affecting the postoperative outcome. The quantity and quality of bone graft is the key to the fusion of bone graft. Any blind or over-reliance on internal fixation without focusing on the thoroughness of decompression and bone grafting techniques can only bring negative results. Complications of internal fixation: While internal fixation of the cervical spine is widely used and brings exact efficacy, some complications related to internal fixation are inevitable, such as loosening, slipping or even breaking of the plate screw, anterior screw implantation into the intervertebral space or fixation across the normal vertebral segment, etc. Most of these complications are related to unskilled surgical techniques or insufficient understanding of surgical principles and biomechanics. It is not uncommon to see medically induced screw implantation into the spinal canal, accidental injury to the vertebral artery, nerve roots, or esophageal fistula due to screw slippage. (5) Neighboring segment degeneration: The exact factors of neighboring segment degeneration are unknown, but may be related to too strong internal fixation and too many fixed segments; fusion in a non-physiological state (cervical physiological curvature not restored) can easily lead to neighboring segment degeneration; misuse of internal fixation increases the incidence of neighboring segment degeneration in addition to increasing the patient’s burden.