Spondylolisthesis is a Latin term for slipped vertebral body. “Spondylo” means vertebrae and “listhesis” means slippage. One type of spondylolisthesis, degenerative spondylolisthesis, describes a condition of forward slippage of one vertebrae in the spine over another, usually occurring at age greater than 60. This condition in adults is most commonly due to degeneration, wear and tear, of the discs and ligaments in the spine.
In degenerative adult spondylolisthesis, the discs and the facet joints lose their ability to support the spine and resist gravity therefore, with weight bearing, one vertebrae slips in relation to the other. Back pain is the most common symptom, but severe nerve compression can occur with numbness in the legs, tingling and weakness, particularly with activities. Imaging studies such as MRI and CT scans can show “stenosis,” or pinched nerves in the spinal canal. The CT and MRI scan are obtained with the patient lying down and therefore can miss a slippage. This is why we obtain flexion, extension and standing X-rays, as well as myelograms.
Osteoarthritis of the facet joints can also lead to instability of a vertebral segment. Typically, as continued degeneration weakens the facet joints, the L4 vertebral body slips forward on the L5 vertebral body. Since the L4-L5 segment is the area with the most flexion-extension type movement, this area is most likely to slip. The next most likely level is L3-L4, and rarely L5-S1. This is contrary to isthmic spondylolisthesis that occurs most often at L5-S1.
As the body tries to capture the unstable segment, the facet joints get bigger and place pressure on the nerve root causing lumbar spinal stenosis. Therefore, both the symptoms and conservative treatment for degenerative spondylolisthesis are essentially identical as for patients with lumbar spinal stenosis.
The best way to treat mild to moderate symptoms caused by degenerative spondylolisthesis is with rehabilitation and exercises. The body thrives on activity and has its own mechanisms to treat and heal itself. Conservative treatment using stabilization exercises, part-time bracing, and aqua therapy can be successful in mild conditions. Surgery should be considered only if the pain is persistent and severely debilitating, or if there are neurologic abnormalities or weakness. The exception is when there is bladder or bowel incontinence or progressive weakness.
A vast majority of patients suffering from leg pain will naturally recover given time and non-operative treatment. Non-operative treatments include strengthening exercises, physical therapy, chiropractic, acupuncture, traction, epidural injections, pain medications, and anti-inflammatory medications including steroids.
For buttock or leg pain and mild weakness (radicular symptoms), generally at least 6 weeks of non-operative treatment is pursued to monitor for natural recovery. The waiting period is based on the knowledge that 80-90% of radicular symptoms are known to spontaneously recover. If recovery is progressing, more non-operative treatment may be prescribed.
For isolated low back pain, generally at least 6 months of non-operative treatment is pursued to monitor for natural recovery. The waiting period is based on the knowledge that most midline low back pain is known to spontaneously recover within 6 months.
Surgical treatment may be suggested to treat pain that has not responded to non-operative treatment or if there is severe neurologic deficit such as bowel or bladder incontinence or progressive weakness in vital muscle groups. With the exception of the presence of severe neurologic deficits, the decision to proceed with surgery is a quality of life decision.
The surgical treatment for spondylolisthesis must aim at not only decompressing the nerves, but also stabilizing the spine in an optimal position. Various surgical approaches have been developed to treat adult spondylolisthesis. If the spine is found to be very unstable (excessive motion at the level of slip), then a fusion is commonly performed. Very good results can be obtained with proper surgical technique in carefully selected patients.
Surgical options for degenerative spondylolisthesis are listed below. These surgical options often include a combination of surgical treatments (i.e. decompression, fusion, instrumentation). For a detailed explanation of the individual treatments, please visit the Surgical Treatments section of the web site.
1. Lumbar Laminectomy and Posterior Fusion with Instrumentation
With this procedure, the compression on the nerves is relieved and the motion between the vertebrae arrested by placement of bone and instrumentation to hold the vertebrae together until they fuse. This procedure is the most commonly performed procedure when there is abnormal motion between vertebrae (spondylolisthesis). Arguably, the instrumentation increases the chance of fusion.
2. Lumbar Laminectomy and Posterior Fusion without Instrumentation
With this procedure, the compression on the nerves is relieved and the motion between the vertebrae arrested by placement of bone to allow the vertebrae to fuse together. This procedure is helpful when there is abnormal motion between vertebrae.
3. Lumbar Laminectomy, Lumbar Interbody Fusion,Posterior Fusion with Instrumentation
With this procedure, similar to the above procedures, the compression of the nerves is relieved and motion between the vertebrae arrested. In addition, the disc space height is restored which is helpful for restoring normal curvature of the spine and decompressing the narrowed foramen. The fusion rate is also shown to be higher than posterior fusion alone since there is additional surface area for fusion. The interbody procedure is also referred to as “PLIF” (Posterior Lumbar Interbody Fusion) or “TLIF” (Transforaminal Lumbar Interbody Fusion) based on how the interbody is approached.
4. Minimally Invasive Procedures (MIS)
Posterior foraminotomy, instrumentation, and fusion can be performed through tubes, minimizing the muscle damage during these procedures. This is a rapidly evolving area of research and innovation at this time.
5. Anterior Lumbar Fusion, Lumbar laminectomy, Posterior Fusion with Instrumentation
In patients who develop severe deformities including lumbar flatback or lumbar scoliosis, a combined anterior fusion and posterior decompression and fusion with instrumentation may be necessary to restore the normal alignment of the lumbar spine. This procedure allows excellent restoration of the disc height which is helpful for restoring normal curvature of the spine and decompressing the narrowed foramen. The fusion rate is also shown to be higher than posterior fusion alone since there is additional surface area for fusion.
6. Lumbar Laminectomy / Foraminotomy
This is a decompression procedure. With this procedure, the lamina and overgrown facet joints are removed to make room for the nerves. This is the most common treatment for lumbar stenosis where there is bilateral buttock/leg symptoms. However, well performed studies have shown that laminectomy alone does not have as favorable an outcome as laminectomy with fusion. In selected patients with a fixed spondylolisthesis (no motion on flexion/extension), decompression alone may be a viable treatment option.
7. Lumbar Laminotomy / Foraminotomy
This is also a decompression procedure. This procedure is used to remove part of the lamina and overgrown facet joint to relieve unilateral leg symptoms. This is the helpful when there is unilateral buttock/leg symptoms. However, well performed studies have shown that laminotomy or laminectomy alone do not have as favorable an outcome as laminectomy with fusion. In selected patients with a fixed spondylolisthesis (no motion on flexion/extension), decompression alone may be a viable treatment option.
Spondylolisthesis Case Study
The patient is a 64 year old female with severe buttock pain when she walks greater than 2-3 minutes. In addition, she experiences low back pain during even minimal lifting or bending activities. Her lumbar radiographs (Images A & B) show the slippage of L4 relative to L5. L4-5 is the most commonly affected level with degenerative spondylolisthesis.
The MRI scan reveals severe spinal stenosis at L4-5, and relatively normal canal at the adjacent levels (Images C & D).
Note the severe stenosis at L4-5 in red (Images E & F), and the normal canal at L3-4 in blue (Images E & G)
She underwent L4-5 laminectomy and fusion with instrumentation (Image H). Usually, interbody fusion is unnecessary.