SpondylolisthesisMinimally Invasive Surgery
Symptoms of Spondylolisthesis
- Low back pain
- Buttock pain
- Leg pain
- Weakness in the lower extremities
- Numbness or burning in the leg
- Bowel or bladder incontinence
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.
Minimally spine surgery procedures approach the spine from the front (anterior), back (posterior), side (lateral), or back and side (posterolateral). Procedures such as those listed below share the same surgical goals:
- Anterior Lumbar Interbody Fusion (ALIF)
- Direct Lateral Interbody Fusion (DLIF / XLIF)
- Transforaminal Lumbar Interbody Fusion (TLIF)
- Trans-sacral Fusion at L5-S1
The interbody device, such as a Titanium cage or PolyEthylEther Ketone (PEEK) spacer, is implanted into the disc space. Bone graft is packed into and around the device to stimulate spinal fusion.
- ALIF provides access to the spine and disc through the abdomen. This procedure is often combined with posterior fusion and instrumentation for better spinal fixation.
- DLIF provides access to the spine through the side of the body. This procedure involves a transpsoas approach, which means the surgeon accesses the spine through the psoas muscle; a long muscle on both sides of the lumbar spine.
- TLIF provides access to both sides of the disc through the intervertebral foramina, small passageways through which nerves exit the spinal canal. An interbody device, such as a cage or spacer is implanted into the disc space from one side of the spine. Pedicle screws and rods, with additional bone graft, secure the back (posterior) section of the spine. TLIF fuses the front and back sections of the spine.
- Trans-sacral Fusion is a novel technique that uses a long screw inserted from the back. The L5-S1 level is reached through an incision near the tailbone. Behind the pelvis at the rectum dissection is performed; the L5-S1 disc is removed and bone graft inserted through the trans-sacral device. Usually, additional screws and rods are placed to ensure maintenance of spinal alignment.
During spinal fusion, the surgeon locks together, or fuses, some of the bones in the spine. This limits the movement of these bones, which may help relieve pain. The back or neck won’t be quite as flexible. Even so, one may feel more flexible after a fusion because one can move with less pain. Like other treatments, fusion surgery can be performed both anteriorly and posteriorly.
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.
- 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.
- 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.
- 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.
- 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.
- 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.
- 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.