<unk>  of L5-S1 Complete<unk>  - The body of one vertebra is posterior to both the vertebral body of the segment of the spine above as well as below. Stairstepped<unk>  - The body of one vertebra is posterior to the body of the spinal segment above, but is anterior to the one below. Partial<unk>  - The body of one vertebra is posterior to the body of the spinal segment either above or below. (3) Grading Since the vertebral body in a<unk>  moves in a posterior direction, the grading used for spondylolistheses is of little use. It is however useful to divide the anterior to posterior dimension of the intervertebral foramina (IVF) (4) into four equal units. A posterior displacement of up to ¼ of the IVF is graded as Grade 1, ¼ to ½ as Grade 2, ½ to ¾ as Grade 3, ¾ to total occlusion of the IVF as Grade 4. Alternatively, a measurement of the amount of displacement can also made by measuring the bone displacement in millimetres.<unk>  can be caused by injury and the resulting instability of the connecting soft tissues especially ligaments, discs, muscles, tendons and fascia. They may also involve muscles through spasm as a result of nerve malfunction due to pressure caused by the posterior displacement of the vertebra encroaching on the contents of the IVF. The IVF's contents include spinal (sensory and motor) nerves, arteries, veins and lymphatic vessels which cater to the nutritional and waste removal needs of the spinal cord. Degenerative spinal changes are often seen at the levels where a<unk>  is found. These changes are more pronounced as time progresses after injury, and are evidenced by end plate osteophytosis, disc damage, disc narrowing, desiccation and disc bulging. “A<unk>  hyperloads at least one disc and puts shearing forces on the anterior longitudinal ligament, the annular rings, nucleus pulposus, cartilage end plates and capsular ligaments. The bulging, twisting and straining tissues attached to the endplates pull, push and stretch it. It is worsened with time, becoming irreversible.” This is the etiology of degenerative joint disease. (5) 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<unk>  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.
Retrolisthesis
Spondylolisthesis
Disc protrusion
Back strain
Facet syndrome
Vertebral compression fracture
Discitis
Coccyx fracture