erative spondylolisthesis representing
spinal instability. X-ray image shows
6 mm of forward slippage of L4
(bottem corner labeled "a") on L5
(top corner labeled "b").
Spondylolisthesis refers to the forward displacement, or slippage, of a vertebra from its normal position. The two most common sites for spondylolisthesis are the forward slippage of the fourth lumbar vertebra (L4) over the fifth lumbar vertebra (L5) or the forward displacement of the fifth lumbar vertebrae over the first sacral vertebra (S1). (see ANATOMY) This forward slippage, depending on the degree of severity, can cause the vertebra to encroach on the spinal canal, resulting in spinal stenosis. Approximately 80% of patients evaluated for degenerative spondylolisthesis have some degree of spinal stenosis. Degenerative spondylolisthesis is caused by degenerative changes of the disc and corresponding facet joints (tri-joint complex) with secondary weakening of ligamentous restraints. These anatomic entities contribute important stability and unity to the vertebral column. Loss of their normal structural anatomy has consequences of relative spinal instability [Figure 1 ]. With increasing age and further disc and facet joint degeneration, the degree of slippage may progress into adulthood.
Your doctor will be able to measure the degree of slippage by measurements taken on X-ray films. Slippage is graded as low (mild) to high (advanced) (see above).
Nonoperative treatment includes bed rest, medication, temporary bracing, epidural injections, and exercise programs with abdominal strengthening and flexion exercises. Bracing can be used as an initial temporary support. Prolonged bracing is discouraged, for this may lead to muscle atrophy and fatigue. A rehabilitation program should emphasize correct posture and body mechanics to learn to avoid unnecessary twisting and rotation movements during the work day and at home.
The occurrence of a neurological defect, intractable pain, failure of nonoperative treatment, and functional incapacitation are indications for surgical intervention.Spinal fusion with implants is usually recommended. In few instances, the narrowed disc space and bridging osteophytes (new vertical bone formation between vertebrae), which are a consequence of the disease process, may provide enough stability to avoid surgery or at least implants.