Fig. 4. Injuring force mechanisms and resulting lesions. In A , a compression hyperextension force has resulted in distraction of the elements of the anterior column and compression of posterior column elements; an avulsion fracture from the anterior-inferior margin of the vertebral body ( small arrow 2 ) and a fracture of the articular process ( small arrow 1 ) have resulted. In B , a flexion ( large arrow 2 ), compression ( large arrow 1 ) force has produced a wedge fracture of the vertebral body ( small arrow 2 ) and an incomplete disruption of the interspinous and supraspinous ligaments ( small arrow 1 ).