Traumatic Spondylolisthesis

A review of the literature indicates that while dislocations of the fifth lumbar vertebra have been diagnosed and reported, the condition is exceedingly rare.1 It is only within recent years that the diagnosis suggested by the history and clinical examination can be confirmed by roentgenograms.Even today the peculiar and unusual roentgeno- graphic appearance is not recognized by many.An anteroposterior picture of a forward dislocation of the fifth lumbar vertebra is, how- ever, so striking that when once seen and understood, a second case will not be overlooked.Roentgenographic definition of the structures in the lumbosacral region is difficult because: (1) The fifth lumbar vertebra has a wide range of normal morphologic variation; (2) the forward inclination of the fifth lumbar vertebra and the sacrum makes it difficult to obtain a clear outline of these bones; (3) overdeveloped transverse processes of either the last lumbar or first sacral segment change or obscure the relation of the fifth lumbar, sacrum and iliac bones, and (4) the proximity and size of the iliac bones interfere with a good lateral view of the fifth lumbar vertebra and especially of the lumbosacral joint.In studying the lumbosacral region, anteroposterior, lateral and oblique views are necessary to obtain the fullest possible information.Stereoscopic roentgenograms are preferable to flat impressions.Dr. Byron C. Darling recently described very clearly the roentgen- ray appearance of the anteroposterior picture of a bilateral forward dislocation of the fifth lumbar vertebra.He reported five cases from the services at the Hospital for Ruptured and Crippled.The appear¬ ance was the same in all.In these cases, as in the two about to be described, there was a bilateral forward subluxation of the fifth lumbar vertebra.The dislocation in all but one of the cases in the literature was incomplete.In one instance, an anatomic specimen, there was complete dislocation of the fifth lumbar vertebra, which was found to lie on the anterior surface of the sacrum.1.