Upper cervical spine injury level and classification (N = 120).
| Variable | n (%) |
| Injury level | |
| C1 | 11 (9.2) |
| C2 | 84 (70.0) |
| C1-C2 | 21 (17.5) |
| C2-C3 | 4 (3.3) |
| Injury classification | |
| Type I C1 fracture (ring fractures) | 7 (5.8) |
| Type II C1 fracture (Jefferson’s fracture) | 2 (1.7) |
| Type III C1 fracture (lateral mass fracture) | 2 (1.7) |
| Hangman’s fracture | 16 (13.3) |
| Type II odontoid fractures | 35 (29.2) |
| Type III odontoid fractures | 4 (3.3) |
| Miscellaneous C2 fractures | 24 (20.0) |
| C1-C2 dislocations | 4 (3.3) |
| C2-C3 dislocations | 2 (1.7) |
| Atlanto-occipital displacement | 2 (1.7) |
| Type II C1 fracture (Jefferson’s fracture) + type II odontoid fracture | 2 (1.7) |
| Type II odontoid fracture + atlanto-occipital displacement | 2 (1.7) |
| Type II odontoid fracture + hangman’s fracture | 4 (3.3) |
| Type III odontoid fracture + miscellaneous C2 fractures | 2 (1.7) |
| Type I C1 fracture + type II odontoid fractures | 3 (2.5) |
| Type III odontoid fracture + C1-C2 dislocations | 2 (1.7) |
| Type I odontoid fractures + C1-C2 dislocations + miscellaneous C2 fractures | 3 (2.5) |
| Type II C1 fracture (Jefferson’s fracture) + type III odontoid fracture | 2 (1.7) |
| Type III C1 fracture (lateral mass fracture) + miscellaneous C2 fractures | 2 (1.7) |