It was decided that surgical intervention is indicated for this acute type II odontoid fracture. Magnetic resonance imaging (MRI) was performed and the transverse ligament was intact (Fig. 83.2). We elected against halo placement in this patient given the patient’s age, associated comorbidities (multiple rib fractures), and the higher risk for nonunion with a halo.

The patient successfully underwent placement of a single odontoid lag screw under general anesthesia (Fig. 83.3). The use of one screw is thought to have similar biomechanical strength as two screws side by side.¹ Successful reduction of the fracture segment was obtained during patient positioning. The patient was placed in a hard collar for 3 months. She remained neurologically intact and without neck pain. Follow-up radiographs demonstrated good bony union of the fracture segment.

• The sagittal radiograph of the cervical spine demonstrates a fracture of C2, at the base of the odontoid process, consistent with an acute type II odontoid fracture.
  
• There is significant retrolisthesis of C1 compared with C2.
  
• The atlantodens interval is within normal limits.

• MRI is indicated to assess the status of the transverse and alar ligaments as well as the tectorial membrane. The integrity of the transverse ligament in addition to the atlantoaxial distances and relationships significantly affects your management and operative approach.²

• Anderson and D’Alonzo’s classification is described below (Fig. 83.4).³
  
  
  
  • Type I fractures occur through the tip of the dens above the transverse ligament. These are rare injuries and associated occipital–cervical dislocation should be excluded. ⁴
    
  • Type II fractures occur through the base of the neck and are the most common fracture subtype.
    
  • Type IIA fractures are similar to type II, but there is comminution and large bone fragments at the fracture site.
    
  • Type III fractures occur through the body of C2 and may involve the articulating facet and marrow space. Type III fractures may be better characterized as horizontal rostral C2 body fracture and not odontoid process fractures. ⁵
  
  
• Type I and III fractures are often treated in a conservative fashion. ³ That said, one must consider “shallow” or “high” type III odontoid fractures as potentially unstable fractures.^4,6 Furthermore, anteriorly displaced type III fractures may also be unstable.
  
• Attention should be given to the extent of articulating facet injury/ distraction, which can be seen with these injuries. ⁷
  
• It is generally accepted that advanced age, fracture displacement >6 mm, and angulation >10 degrees negatively influences union rates.4,8 Other factors include chronicity of the fracture,⁹ delay in diagnosis, fracture comminution,⁴ or inability to maintain fracture alignment with external immobilization.¹⁰
  
• Type II odontoid fractures in patients 50 years and older should be considered for surgical stabilization and fusion.¹⁰ This is based on a 21 times higher rate of nonunion in patients over the age of 50.¹¹

• Contraindications for anterior odontoid screw fixation include the inability to reduce anatomically the fracture, nonunion, severe osteoporosis, transverse atlantal ligament rupture, or concomitant Jefferson-type fracture with coronal plane separation of >7 mm, or oblique fracture from anteroinferior to postero-superior.¹²
  
• Furthermore, this procedure is difficult in patients with short necks, barrel chests, those unable to tolerate cervical extension (spinal stenosis), or those with tracheostomies or significant open trauma to the anterior aspect of the neck.

• Typically reduction of an odontoid fracture is obtained under fluoroscopy during operative positioning in the supine position with the Mayfield head-holder.
  
• Alternatively, Gardner-Wells tongs or manual cervical traction can be utilized to obtain reduction under fluoroscopy. Bivector traction with a flexor component is also an option.

• Details of the procedure are described below¹³ and are illustrated in Fig. 83.5.¹⁴
  
• The patient is positioned supine. The Mayfield head holder is utilized and the head is fixed in extension. Alternatively, intraoperative traction with Gardner-Wells tongs is utilized.
  
• High-resolution biplanar fluoroscopic imaging is utilized to ensure reduction of the anterior displaced fracture segment and to guide screw placement.
  
• An anteromedian neck incision is placed in the region of C5–C6.
  
• An avascular plane is dissected cephalad until the anteroinferior border of C2 is reached.¹⁵
  
• A Hohmann retractor may be used to aid in exposure. Then, a high-speed drill is used to make a trough in the superior portion of C3 to allow for a proper angle when drilling a pilot hole.
  
• A K-wire is inserted and then a long 2.5 mm cannulated drill is inserted into the trough and angled posterior to reach the dorsal portion of the odontoid tip.
  
• On the anteroposterior projection midline trajectory is confirmed.
  
• The pilot hole is drilled, and the depth of the hole is measured.
  
• Then the appropriate-length 3.5-mm cannulated lag screw is placed through the pilot hole to obtain bicortical purchase.^16,17 Compression of the fracture segment should be seen.

• The development of high cervical neck pain or signs of myelopathy may signal nonunion.
  
• An anterior odontoid screw is not recommended at this time secondary to fibrous scar, which is present at the fracture site.
  
• In this situation, a posterior C1–C2 fusion would be indicated.^4,18,19

• Screw breakage may be a sign of nonunion. Initially, a computed tomography scan of the cervical spine and flexion–extension x-rays should be performed. If a clear lucency is appreciated near the fracture site or if there is movement of the fracture segment, then a posterior cervical C1–C2 fusion should be considered.^18,19