Spondylolisthesis is usually fixed (ie, permanent and limited in degree). It usually involves the L3-L4, L4-L5, or most commonly the L5-S1 vertebrae.
Spondylolisthesis often occurs in adolescents or young adults who are athletes and who have had only minimal trauma; the cause is a weakening of lumbar posterior elements by a defect in the pars interarticularis (spondylolysis). In most younger patients, the defect results from an overuse injury or stress fracture, although it may be caused by a single severe impact. Also, degenerative spondylolisthesis can occur in patients who are > 60 and have osteoarthritis; this form is six times more common in women than men.
Mild to moderate spondylolisthesis (anterolisthesis of ≤ 50%), particularly in the young, may cause little or no pain. Spondylolisthesis can predispose to later development of foraminal stenosis.
Spondylolisthesis is graded according to the percentage of vertebral body length that one vertebra subluxes over the adjacent vertebra:
Spondylolisthesis is evident on plain lumbar x-rays. The lateral view is usually used for grading. Flexion and extension views may be done to check for increased angulation or forward movement.
Treatment of spondylolisthesis is usually symptomatic. Physical therapy with lumbar stabilization exercises may be helpful.