Transverse Ligament Rupture (Traumatic C1–C2 Instability)

This rare, usually fatal, injury is seen mostly in older age groups (50s to 60s).

The mechanism of injury is forced flexion.

The clinical picture ranges from severe neck pain to complete neurologic compromise.

Rupture of the transverse ligament may be determined by:

1. Visualizing the avulsed lateral mass fragment on CT scan.

2. Atlantoaxial offset >6.9 mm on an odontoid radiograph.

3. ADI >3 mm in adults. An ADI >5 mm in adults also implies rupture of the alar ligaments.

4. Direct visualization of the rupture on MRI.

Treatment

• Initial treatment includes halo traction/immobilization.

• In the cases of avulsion, halo immobilization is continued until osseous healing is documented.

• C1–C2 fusion is indicated for tears of the transverse ligament without bony avulsion, chronic instability, or pain (Fig. 9.7).