AO/Magerl classification of spinal injuries. A, Compression injuries: A1, impaction; A2, split; A3, burst. B, Distraction injuries: B1, posterior ligamentous; B2, posterior osseous; B3, anterior through disc. C, Torsion injuries: C1, type A with torsion; C2, type B with torsion; C3, torsion shear.