ABSTRACT
I DEFINITION BY MECHANISM Distractive flexion (DF) injuries of the cervical spine have long been referred to in the literature as perched, subluxed, or dislocated facet injuries. Formal recognition and distinction of distractive flexion and compression flexion injuries of the cervical spine originated from the mechanistic, clock-face classification first put forth by Drucker et al. in the late 1970s (1). This clock-face representation was further popularized with a subclassification by Allen and Ferguson (2). They describe a continuum of osseous and ligamentous injury that comprises the clinical spectrum of injuries illustrated in their paper as hyperflexion sprains, unilateral facet dislocations, bilateral facet dislocations, and complete-fracture dislocations. The classic article (2) described 165 cervical injuries, including 61 cases of distractive flexion injuries. On the clock-face diagram, these injuries occur with the force vector in the 9:00 to 11:30 direction (Fig. 1). Stages of injury or phylogenes are described. Understanding the pathoanatomical basis of each phylogeny is very helpful in defining the injury and deciding treatment options.
