Spondylolisthesis occurs when one vertebral body abnormally slips forward or backward on the vertebral body below.
It can be referred to as a “slipped vertebral body”. A large majority of cases occur in the lumbar spine at L5 or L4, but it can infrequently occur in the cervical and thoracic spine.
The most common causes of spondylolisthesis are termed isthmic and degenerative. Isthmic spondylolisthesis results from a stress fracture at both sides of the pars interarticularis.
This often occurs in adolescent athletes (especially football, gymnastics, wrestling, and dancers) due to rapid growth of bone being more susceptible to shearing injury.
Degenerative spondylolisthesis often occurs in those over age 50 and results from long-standing intervertebral disc, facet joint, and ligament ‘wear-and-tear’, resulting in a lack of stability between the two segments.
Less common causes include congenital, traumatic, and post-surgical. Post-surgical instability can occur if too much supporting facet joint and other structures are removed.
Isthmic spondylolisthesis is typically suddenly symptomatic, causing low back pain with or without sciatica.
The pain may spontaneously resolve even though the slippage is still present.
This is problematic because one may not know that the ongoing instability puts them at heightened risk of a more severe back injury even with a low-force injury.
Degenerative spondylolisthesis often occurs slowly.
If the grade of slippage is mild, it may remain minimally symptomatic, causing infrequent and brief episodes of low back pain.
A relatively minor injury can significantly “light up” the condition. If the grade of slippage increases, it places one at higher risk for progressive symptoms, including worsening back pain, sciatica, hamstring spasms, or leg numbness and weakness.
The specific cause of back pain in spondylolisthesis can be due to a variety of anatomic structures, including the facet joints, intervertebral disc, tight back and hamstring muscles, and/or strained ligaments.
Spinal stenosis can occur if the slippage impinges the nerve roots or spinal cord in the spine’s central canal or foramen, and can cause sciatica, leg numbness and weakness, and, infrequently, abnormal function of the bladder or bowel.
A medical history and physical examination are helpful, but a x-ray is needed to diagnose the condition, classify its severity (grade 1 to 5), and assess for abnormal motion while one is bending.
Signs of nerve injury and certain x-ray findings will necessitate getting a MRI.
It is imperative that a child with back pain not return to sports or injury-prone activities.
Any child with severe low back pain, pain that does not resolve within a few days, or back pain that radiates down a leg needs to be evaluated by a physician with knowledge of back pain in children.
Anyone with leg numbness, leg weakness, or abnormal bowel or bladder function needs to seek care urgently.
Treatment depends on the degree of the slippage, severity of symptoms, and presence of nerve injury. Conservative care options may include therapeutic exercise (i.e. physical therapy, core strengthening, McKenzie method), medications, epidural steroid injections for sciatica, and facet joint injections for back pain or facet joint cysts.
Surgery is reserved for those with nerve injury or those who do not respond to conservative measures.