Abstract: OBJECTIVE: To investigate the diagnosis and treatment strategy of traumatic instability of the upper cervical spine. METHODS: A group of 27 cases of traumatic instability of the upper cervical spine was retrospectively analyzed, and the diagnosis was divided into 7 cases of dentate fracture combined with atlantoaxial dislocation, 3 cases of transverse dentate ligament injury combined with atlantoaxial dislocation, 6 cases of jifferson fracture, 7 cases of Hongman fracture without displacement, and 4 cases of Hongman fracture combined with severe C2 vertebral body dislocation, and 16 cases were treated surgically and 9 cases non-surgically. RESULTS: No complications such as spinal cord injury or vertebral artery rupture occurred in all cases. All cases were effectively followed up with an average follow-up time of 9 months, and all cases obtained fracture healing and bony fusion, and the instability of the upper cervical spine was effectively corrected. Conclusion: The diagnosis and treatment choice of traumatic instability of the upper cervical spine depends on the type of fracture and fracture displacement. Injuries to the transverse odontoid ligament combined with atlantoaxial dislocation and unstable jifferson and Hongman fractures should be treated surgically, and precise measurements and individual design based on preoperative radiographs and CT films are a good guide for upper cervical arch fixation. Li Bo, Department of Orthopedics, People’s Hospital of Guizhou Province
Keywords upper cervical spine; instability; bone graft fusion; internal fixation.
Fractures of the upper cervical spine are mostly the result of stress to the head in the vertical and rotational directions, which can cause life-threatening injury to the spinal cord and vertebral artery in the high cervical segment. The anatomical structure of the upper cervical segment is complex, the location is deep, and the surgery is difficult and high-risk. Due to the development of imaging and in-depth understanding of this type of injury, the clinical diagnosis level has been improved and the leakage rate has been greatly reduced.
Clinical data and methods
General data
Among the 27 cases, 18 were male and 9 were female, aged from 18 to 68 years old, with an average of 45.2 years old. 8 cases were injured in car accidents, 7 cases were injured by heavy objects on the head, and 12 cases were injured by falls. All patients had a history of head and neck trauma, felt pain and discomfort in the occipital neck, stiffness and inability to move the neck, 9 cases had transient numbness and weakness of the limbs, 17 cases had no obvious symptoms of cervical spinal cord damage, and 1 case had progressive symptoms of cervical spinal cord damage, numbness and weakness of the limbs, and tendon hyperactivity of the limbs.
Imaging data and diagnosis
All patients routinely underwent open-oral and cervical front and lateral radiographs, and all underwent atlantoaxial CT scan and three-dimensional reconstruction of the occipito-atlanto-axial spine to understand the fracture and spinal canal, and cervical MRI examination to understand the spinal cord. Bilateral vertebral arteriograms were routinely performed before surgery to understand the damage to the vertebral arteries and the presence of deformities. All patients were braked with a cervical brace at the time of examination, including 8 cases of combined atlantoaxial transverse ligament injury, 4 cases of atlantodental fracture type II fracture, 3 cases of combined lateral mass fracture, 6 cases of which the sum of lateral mass displacement (LMD) on both sides was greater than 6.9 mm, and the atlantodens interval (ADI) was greater than 4 mm in 9 cases. There were 7 cases of Hongman fracture without displacement, 4 cases of Hongman fracture with severe dislocation of C2 vertebrae, and 2 cases of old atlantoaxial dislocation.
Treatment method
After 2 weeks, 2 cases were treated with Halo-vest fixation, 3 cases were fixed with cervicothoracic plaster support, 2 cases were fixed with cervicothoracic plaster, and 3 months were fixed with cervical extension and flexion lateral films to understand the stability of the occipito-atlantoaxial spine. The atlanto-axial fracture fusion was detected by CT scan.
In this group, 18 cases were treated surgically, 8 cases were treated with the atlantoaxial pedicle system, and 2 cases were treated with occipital neck fixation using pedicle screws due to severe atlantoaxial fragmentation, and atlantoaxial interlaminar bone graft fusion without atlanto-occipital bone graft. Four Hongman fractures combined with severe C2 vertebral dislocation were treated with anterior decompression and fixation, and two old atlantoaxial dislocations were treated with posterior repositioning atlantoaxial screw fixation. Two anterior odontoid screw fixation was performed for type II odontoid fractures.
Results
All patients in this group were followed up from 6 months to 2 years, with a mean of 9 months. The 9 patients who received conservative treatment were reviewed 3 months after the injury, and all fractures were fused, with no significant instability of the occipito-atlantoaxial spine, and they were asked to move and exercise their necks and then review the films again to see good stability. In the patients who received surgical treatment, the neck pain was significantly relieved, the numbness of the neck disappeared, the neurological symptoms were significantly reduced, the position of the internal fixation was good on imaging review, there were no broken nails and rods on postoperative review at 3 months, there was no occipito-atlantoaxial instability, the fracture severed ends healed well, and the local bone graft fused well.
Discussion
Upper cervical fractures are mostly caused by axial compression forces or longitudinal violence, and the anterior and posterior atlantoaxial arches are often separated from the lateral blocks, resulting in subluxation or subluxation of the occipito-atlanto-axial and atlanto-axial joints and thus affecting the occipito-cervical activities. Atlantoaxial instability puts the cervical spinal cord at high risk, so the treatment of atlantoaxial burst fractures focuses on correcting the dislocation, relieving the compression, and restoring the stability of the atlantoaxial joint. The stability of the atlantoaxial joint depends on the integrity of the atlantoaxial transverse ligament and the dentate process. If an atlantoaxial fracture affects the integrity of the transverse ligament, it can cause occipital and cervical instability, so whether the atlantoaxial fracture is combined with a rupture of the transverse ligament is an important clinical indicator of its stability.
The cervical spine consists of 7 vertebrae, with the uppermost atlas and the cardinal vertebrae forming the atlantoaxial joint. The atlantoaxial joint is structurally distinct from the five joints below cervical 2 and 3. The atlantoaxial joint has the largest range of motion of any joint in the spine and is therefore the most unstable joint, prone to fracture and dislocation due to trauma. The stability of the atlantoaxial joint depends primarily on the integrity of the atlanto-dental process and the transverse atlantoaxial ligament, the absence of which can result in atlantoaxial instability. As atlantoaxial instability increases, the atlantoaxial spine becomes more anteriorly displaced and tilted forward and downward, and the ligaments and musculature in front of the upper cervical spine (e.g., anterior longitudinal ligament, cephalicus longus, cervicalis longus) contract, preventing repositioning of the atlantoaxial spine. The atlantoaxial joint then progresses from instability to fixed dislocation.
In clinical practice, atlantoaxial fusion should be performed whenever atlantoaxial instability is present. The instability will increase with time and eventually lead to dislocation. In addition, in the case of atlantoaxial instability, the cervical spinal cord is easily stimulated by repeated excessive activity, and spinal cord injury and paralysis may occur under the effect of a single violence.
The surgical treatment of upper cervical instability or dislocation should conform to the following basic principles: 1, atlantoaxial fusion should be performed in unstable cases. 2, only the atlantoaxial joint should be fused. 2. Only the atlantoaxial joint should be fused. The fusion between the occipital bone and the pivot should be done only in the case of combined atlanto-occipital ossification deformity (occipito-cervical fusion). 3. A strong internal fixation device should be used so that the implant can be fused after surgery without relying on external fixation. 4.The internal fixation device must be fixed in short segments, and should not be fixed beyond the range for the pursuit of stability. 5.For cases of atlantoaxial joint fixed dislocation, the atlantoaxial joint should be loosened and repositioned, and then fixed implant fusion should be done after repositioning. Do not fix the atlantoaxial joint in the dislocated position.
We have seen many cases of treatment failure in the clinic, and the reasons for this can be found in the violation of the above basic principles. If we follow these basic principles, we can avoid many cases of revision surgery due to surgical failure. With the increasing maturity of surgical techniques and the continuous improvement of internal fixation materials, as well as the further improvement of intraoperative monitoring equipment and methods, the surgical approach to the upper cervical spine has become more diversified, and various methods of fixation and fusion are safe and feasible, but precise preoperative measurement and design are necessary to follow the principle of individualization.