REF : textbook of ohopedics, John ebnezer, 4th edition ,pg.no.311 Three column concept of spine stability was given by Denis *The anterior column consists of anterior half of the veebral body , anterior pa of the disk & anterior longitudinal ligament. * The middle column consists of posterior half of the body & the disk , posterior longitudinal ligament. *The posterior column consists of the posterior veebral arch consisting of transverse process , spinous process & the accompanying ligaments. One column injury is stable , 2 column injury is unstable - it is a dangerous spine for it may injure the spinal cord.