Hangman fracture is a fracture of the portion of the pivot vertebra between the superior and inferior articular processes under the action of violence, often accompanied by damage to the surrounding ligaments and discs, followed by instability or dislocation of the pivot vertebra, also known as traumatic pivot slippage. With the development of internal fixation technology, two major types of surgical approaches, anterior and posterior, have been formed. The 12 cases of posterior surgery admitted to our hospital from 2000 to 2004 are reported as follows. 1. Clinical data 1.1 General data 9 male cases and 4 female cases, age 22-56 years old, average 34 years old, 7 cases of car accident injury, 3 cases of fall injury, 2 cases of forehead impact injury. 4 cases with incomplete spinal cord injury, including 1 case of typical spinal cord hemisection injury syndrome. 1.2 Imaging data Positive and lateral cervical spine X-ray, CT and MRI were performed in 13 cases. 1 case of type I, 1 case of atypical type Ia combined with fracture of the pivotal vertebrae, 5 cases of type II, 3 cases of type IIa and 3 cases of type III were classified according to Levine-Edwards typing[1]. 1.3 Surgical methods and modalities Routine cranial traction for 1 week and photo review of repositioning. The posterior median incision was made to reveal the posterior arch of C1 to the outer edge of the optic chiasm of C3 vertebral plate. C2 pedicle screw points were placed with the midpoint of the C2 lateral block as the entry point, and 2 mm Kirschner pins were drilled in a direction parallel to the inner superior edge of the narrow part of the cardinal spine, 20º~30º each upward and inward, penetrating the anterior cortex The C1 pedicle entry point is the pivotal pedicle tension screw entry point vertically upward 3 mm below the intersection with the superior border of the posterior arch of C1 [4], with an inward inclination of 5º and an upward inclination angle determined by intraoperative fluoroscopy. 30º each of the C3 lateral block midpoints is obliquely outward. The three points lie in a straight line. There were 8 cases of pivotal pedicle tension screw fixation, 2 cases of C2 pedicle C3 lateral block nail plate system, 2 cases of C2C1 pedicle C2 pedicle C3 lateral block nail plate system, and 1 case of C1 pedicle C3 lateral block nail plate system. Type III was routinely performed with C2C3 interlaminar granular bone graft. The C2 spinous extensor stop was routinely repaired to prevent cervical retroflexion deformity. 2. Results All patients were followed up for 6 to 24 months, with an average of 12 months, and all obtained bony fusion and normalized sensory muscle strength of the extremities in patients with combined spinal cord injury. In patients with C1~C3 nail plate fixation, the head and neck rotation function was normalized after the internal fixation was removed. There was no cervical retroflexion deformity and cervical instability. 3. Discussion 3.1 Diagnosis and typing of Hangman fracture Hangman fracture, also known as traumatic slippage of the cardinal spine, is a stable fracture according to Levine-Edwards typing. Type II fractures are unstable fractures, with vertebral body displacement greater than 3 mm and with angulation. Type IIa fracture is also an unstable fracture with significant angulation of the vertebral body and no significant displacement. Type III fractures have significant displacement and angulation of the vertebral body with unilateral or bilateral subtalar dislocation.Starr [2] et al. found a category of fracture line asymmetrical, where one side of the fracture involves the posterior inferior border of the vertebral body and the fracture mass is displaced to compress the spinal cord, and traction therapy has no repositioning effect, called type Ia fractures, which require open reduction and internal fixation. The lateral hyperextension-hyperflexion film is used to distinguish type I from type II fractures. Type II fractures have increased hyperextension-hyperflexion dependence and angulation, while type IIa fractures have significantly increased angulation. Spiral CT reconstruction is used to diagnose type Ia fractures with significant advantages, and CT is also used to measure and determine the nail entry point. The posterior stability of the fracture is related to the integrity of the C2-3 intervertebral disc, anterior longitudinal ligament, and posterior longitudinal ligament, and MRI observation of the damage to the C2-3 intervertebral disc and anterior and posterior longitudinal ligaments guides surgical treatment. 3.2 Selection of posterior internal fixation Type II and IIa fractures with intact anterior longitudinal ligaments should not be operated anteriorly [1], but posterior surgery can anatomically reposition the fracture and correct the local posterior eminence, which is called “surgery to restore physiological function” by Judet [5]. In our case of type I fracture, MRI showed that the C2-3 intervertebral disc was damaged, and because of the poor self-repair ability of the intervertebral disc, it became the source of instability of the C2-3 intervertebral disc and should be treated surgically [6] with posterior C2 pedicle screw fixation. Type Ia fracture due to the posterior lower edge of one vertebral body, displacement and compression of the spinal cord, traction treatment traction is difficult to reset, open reduction C2 pedicle screw internal fixation is recommended. In one case of type Ia fracture with pivotal body fracture and spinal cord hemisection injury syndrome, internal fixation with C1 lateral block C2 pedicle C3 lateral block nail plate system was performed to maintain the stability of the pivotal spine [Figure 1]. The tension screw technique allows for good immediate repositioning of the Hangman fracture and restoration of stability of the C2-3 segment by interbody compression. Its indications should be limited to cases where the fracture is reducible. For type II and type IIa fractures that can be repositioned intraoperatively, C2 pedicle screw fixation is often used [Figure 2]. For angular displacement or MRI showing C2-3 disc and anterior and posterior longitudinal ligament injuries, the C2 pedicle C3 lateral block nail plate system is used for fixation, and the angulation and displacement are corrected by interbody pressure on C2-3 through the lift of the pivot screw. Type III fractures are difficult to reposition in the prone head and neck forward position due to obvious displacement, and are often associated with articular fractures and difficulty in nailing the pivotal pedicle screws, so the C1C3 lateral block nail plate system is used for repositioning [Figure 3], and C2 pedicle screws are added for fixation according to the intraoperative situation. This method was adopted with good results in two cases in our group. For those with obvious preoperative disc and anterior and posterior longitudinal ligament injuries, it is recommended to perform simultaneous C2-C3 interlaminar granular bone grafting to prevent late intervertebral instability. 3.3 Factors affecting treatment Those who do not achieve anatomical repositioning with conservative treatment are prone to residual cervical occipital pain, poor fracture repositioning and long-term cervical instability, and late C2-3 gooseneck deformity in the distant future [3]. Anterior surgery for type II and type IIa fractures damages the still intact anterior longitudinal ligament, loses the C2-3 intervertebral disc, fails to preserve in situ healing of the pedicle, and develops posterior synostosis [7], and posterior pivot screw fixation preserves C2C3 intervertebral motion. The C1-C3 nail plate system achieves anatomic repositioning and strong fixation with good cervical physiological curvature by pre-bending the plate to compress the C2 arch and the lifting effect on the atlas or increasing the compression of the pivot pedicle screw. Even if the C2 arch mutates, the C1-C3 nail plate system is still safe and effective. The internal fixation was removed six months after surgery, and the head and neck rotation function was good. Good surgical skills, skilled local dissection, preoperative CT measurement of the nail entry point and nail entry angle are necessary for posterior surgery.