Hangman fractures, also known as traumatic spondylilisthesis of the axis (TSA), are fractures involving the cardinal pedicle, isthmus, and articular processes, often combined with injury to the cervical 2 and 3 discs, and most require surgical treatment. Theoretically, anterior cervical 2.3 discectomy, repositioning, and fusion fixation provides maximum biomechanical stability, in addition to high bone fusion strength.
However, the anatomical structures around the upper cervical spine are complex and neurovascular, so if the surgical exposure process is improper, it is easy to damage the surrounding tissues and cause complications. 25 cases of Hangman fracture were treated with anterior submandibular vascular-neural access repositioning, cervical 2.3 discectomy, and fusion internal fixation from September 2006 to July 2009, which resulted in easy surgical exposure process, ideal repositioning, and exact fixation and satisfactory clinical results.
Patients are best admitted to the hospital with cranial traction first and then elective C2.3 anterior decompression, repositioning, and fusion internal fixation. The patient was placed in the supine cervical hyperextension position under general anesthesia, with the mandible deviated to the left, and an anterior submandibular vascular-neural gap approach was used. A horizontal incision parallel to the mandible was made 1 cm below the right mandible, medially to the midline of the neck and laterally to the inner edge of the sternocleidomastoid muscle, and the submandibular gland was revealed by incising the skin, subcutaneous tissue, and broad cervical muscle;
The lingual artery is visible below the diastasis, and below the lingual artery, the neurovascular space above the superior laryngeal nerve and superior thyroid artery is separated by walking obliquely inward, holding the carotid artery outward, holding the trachea, esophagus, lingual muscle and hyoid bone to the opposite side, and then sharply separating the posterior pharyngeal space to reach the C1 anterior arch and C2,3 vertebrae.
The C2,3 intervertebral space is revealed by separating the long cervical muscles on both sides, and the C2,3 vertebral body is fitted with a spreader and braced to reset the C2,3 subluxation. The C2,3 intervertebral disc tissue is excised to the posterior edge of the vertebral body, preserving the bony end plate, and in patients with damaged discs, the nucleus pulposus and fibrous annulus protruding into the spinal canal are removed.
After adequate decompression, intervertebral bone grafting or fusion with an intervertebral fusion device was performed. 8 cases were fixed with a normal anterior cervical plate, and 10 cases were fixed with a DEPUY single pedicle screw plate (UNPLATE). A drainage tube was built into the incision and removed after 24 hours. Patients were taken out of bed on the next day wearing a neck brace and were protected by cervical brace fixation for 6-8 weeks.
All patients completed the surgery successfully. The operative time ranged from 70 to 120 minutes, with an average of 90 minutes. Intraoperative bleeding ranged from 30 to 150 ml, with an average of 50 ml. 2 patients had postoperative choking and coughing, which returned to normal within 5 days after surgery. All patients were followed up for 6-36 months, with an average of 12 months. No fracture redisplacement, internal fixation loosening, or fracture was found after surgery, and all intervertebral implants were fused.
Hangman fracture is a fracture of the bony junction between the superior and inferior articular processes of the pivot vertebrae. The classification is a good guide for clinical treatment and has become the most common classification standard.
Type I: fracture with slight displacement, caused by hyperextension violence plus axial loading. Type II: fracture with >3 mm displacement and significant angulation, where the injury is a vertical fracture of the vertebral arch caused by hyperextension and axial loading, followed by significant flexion violence resulting in posterior disc fiber distraction, significant anterior displacement and angulation of the vertebral body, and the C2.3 disc may be torn by sudden flexion violence. Type IIA: marked angulation and mild anterior displacement of C2.3, with injury caused primarily by flexion and distraction violence.
Type III: associated with bilateral arch and posterior articular process fractures, usually with severe angulation and displacement, with unilateral or bilateral subtalar dislocation. Because of the inaccurate fixation and difficulty in maintaining ideal repositioning with non-surgical treatment, the cycle time is also too long, and the prolonged wearing of a brace causes great discomfort to the patient, and the associated complications can be as high as 12% to 36%. Therefore, most scholars now prefer aggressive surgical treatment for Hangman fractures.
The surgical treatment of Hangman fracture is divided into two approaches: anterior and posterior [2,3].Effendi believes that the instability of the fracture is caused by structural damage to the C2.3 intervertebral body, and posterior surgery is mostly performed by occipital neck or C1-3 posterior fusion which also limits head and neck rotation, while anterior C2.3 intervertebral body fusion is recognized by most scholars. In the past, many scholars believed that various anterior approaches to the high cervical spine have obvious shortcomings, and the dissection is very difficult to reveal, which can easily damage important blood vessels and nerves.
In recent years, the author has adopted an anterior submandibular vascular-neural gap approach, in which the vascular-neural safety gap is used according to the characteristics of the vascular nerves in this area, which not only can reveal the anterior upper cervical spine in a safer way, but also avoid various complications caused by pulling the vascular nerves.
In the mandibular triangle, the subglottic nerve and the lingual artery, which are medial to the carotid sheath and inferior to the bicipital muscle, run transversely toward the submandibular middle, while the supraglottic nerve and the superior thyroid artery, which are easily damaged, run obliquely inward and inferior, which provides a safe operating space between the lingual artery and the supraglottic nerve for us to expose C1-3, and no strain on the supraglottic nerve is required during the whole process of exposure. The author used this incision to fully expose the C1-3 vertebral body, with sufficient space for decompression and internal fixation with bone grafting, and no important vascular or nerve injury occurred in any of the cases.
In some patients, the mandible can block the screw fixation of the C2 vertebral body intraoperatively, and the fixation can be successfully completed by rotating the mandible to the opposite side.
Considerations for the transanterior submandibular vascular-neural gap approach A flat mandibular transverse incision is routinely used in the anterior cervical approach to expose the C2.3 disc and vertebral body, with risk areas in both superficial and deep exposures. In the superficial area, it is important to note that if the posterior mandibular vein is to be ligated, the branches of the mandibular nerve pass upward on the surface of the lateral vein due to the continuation of the common facial vein with the posterior mandibular vein, and the posterior mandibular vein is ligated at the point where it enters the internal jugular vein to avoid injury to the branches of the mandibular nerve and to avoid injury to the superficial branches of the facial nerve.
When separating along the anterior border of the sternocleidomastoid muscle to the deeper part, attention needs to be paid to.
1, When the submandibular gland needs to be removed, attention should be paid to ligating its ducts to prevent postoperative salivary gland fistula, as well as bluntly separating the carotid sheath medially to avoid injury to the vessels.
2. In revealing the posterior belly of the diastasis muscle and the caudate hyoid muscle, excessive pulling of the caudate hyoid muscle should be avoided to prevent injury to the facial nerve.
3.In revealing the lingual nerve, superior laryngeal nerve, and superior thyroid artery, the anterior surgery due to hangman’s fracture can be performed by revealing the vertebral space as well as the inferior border of cervical 2 and superior border of cervical 3 vertebrae without excessive tension.
4.After revealing the long cervical muscle, pay attention to mark its position in the central part of the cervical 2 and 3 vertebrae to avoid the inability to locate the central part of the vertebrae after the operation is completed, resulting in skewed plate placement.
5.Pay attention to the fluoroscopic view of the position of the cervical 2 and 3 vertebrae before placing the plate, if the reset is not satisfactory, it is necessary to reset before placing the plate.