A retrolisthesis is a posterior displacement of one vertebral body with respect to the subjacent vertebra to a degree less than a luxation (dislocation). Retrolistheses are most easily diagnosed on lateral x-ray views of the spine. Views where care has been taken to expose for a true lateral view without any rotation offer the best diagnostic quality. Retrolistheses are found most prominently in the cervical spine and lumbar region but can also be seen in the thoracic area. Classification
Retrolisthesis can be classified as a form of spondylolisthesis, since spondylolisthesis is often defined in the literature as displacement in any direction. Yet, medical dictionaries usually define spondylolisthesis specifically as the forward or anterior displacement of a vertebra over the vertebra inferior to it (or the sacrum). Retrolisthesis is also called retrospondylolisthesis. Signs and symptoms
Retrolisthesis may lead to symptoms of greatly varying intensity and distribution. This is because of the variable nature of the impact on nerve tissue and of the mechanical impact on the spinal joints themselves.Structural instability may be experienced as a local uneasiness through to a more far reaching structural compensatory distortion involving the whole spine. If the joints are stuck in a retrolisthesis configuration there may also be changes to range of motion.Pain may be experienced as a result of irritation to the sensory nerve roots by bone depending on the degree of displacement and the presence of any rotatory positioning of the individual spinal motion segments. The soft tissue of the disc is often caused to bulge in retrolistheses.
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Associated radiological findings include a vacuum phenomenon (in the nucleus pulposis of the adjacent intervertebral disc), reduction of disc height with corresponding loss of the disc space, marginal sclerosis of the adjacent vertebral bodies, osteophyte formation and apophyseal joint instability. With a retrolisthesis there is always a less than ideal positioning of spinal segments. There is also always a reduced anterior to posterior dimension of the spinal canal compared to the way it is supposed to be. The greater the posterior displacement, the more significant it is for producing a dysfunctional spinal cord or even a cauda equina syndrome. Joint stability
Joint stability is easily evaluated by the use of flexion and extension lateral x-ray views of the spine. A summary of part of the DRE tables (6) give a guide as to the implications of the joint instability. If either translation or angular change is determined from flexion to extension to the degree shown in the table below, then Category IV instability is present. See also Joint stability.Translation is a gliding motion where one bone of a joint glides over its neighbour. Management
References

6. Hadley, Lee A. (MD), (1973) “Anatomicoroentgenographic Studies of the Spine”. 390.7. Cocchiarella L., Andersson, G. “American Medical Association Guides to the Evaluation of Permanent Impairment”, 5th  edition, Tables 15- 3, 15-4, 15-5.8. Giles, L.G.F. ; Muller R.; and Winter G.J. (2006) “Lumbosacral disc bulge or protrusion suggested by lateral lumbosacral plain x-ray film – preliminary results.” Journal of Bone and Joint Surgery. British Volume, Vol 88-B, Issue SUPP_III, 450.