Table 1.

Numerical coding for spine in AO is no. 5, sub-classification for segments follows as: 51: cervical, 52: thorax and 53: lumbar. Adding to B and C should be the vertebral body lesions IE. Fracture L2 53–B2 (A3). There are modifiers in cervical spine different to thoracolumbar spine.

AO classification
A	1	1 endplate affected
	2	Both endplates are involved but not the posterior wall
	3	1 endplate and the posterior wall
	4	Both endplates and posterior wall
B	1	Chance fractures
	2	Lesions to posterior ligaments and vertebral body involvement
	3	Hiperextension lesions
C	Any fractures accompanied by rotational displacement