Spondylolisthesis Decompression, Realignment, and Fusion

The main aims of back surgery for spondylolisthesis are to decompress the spine, thereby removing pressure from the spinal nerves and cord, and to create stability in the spine in order to prevent the recurrence of this compression. In the majority of cases this will involve a back decompression procedure, such as a laminectomy, followed by spinal fusion using instrumentation and bone grafts. The operation may be performed using an anterior or posterior approach depending on the location of the slippage and the site of nerve or cord impingement.

Typical surgical procedures for spondylolisthesis in the lumbar spine are anterior lumbar interbody fusion (ALIF), posterior LIF, and transforaminal LIF. These are all decompression surgeries combined with fusion but they each take a different approach to the spine in order to provide the surgeon with the most appropriate site and scope of access to the pertinent structures. In some cases the surgeon will not attempt to realign the spine, electing instead to ensure that the pressure is removed from the spinal nerves and the spine is stabilized. The type of decompression surgery carried out depends on the cause of the spinal stenosis and nerve impingement. The nerve compression associated with spondylolisthesis is usually caused by a narrowing of the foramen as the vertebrae moves forward, a herniated, bulging, or ruptured disc, central spinal stenosis (where the spinal cord and/or spinal nerves are compressed), or a Gill fragment which is where part of the facet joint fractures and causes pinched nerves in the spine.

Back surgery for spondylolisthesis addresses each problem individually, with a discectomy appropriate where the compression material is due to a disc herniation or bulge. A foraminotomy is more applicable where the spinal slippage has caused a narrowing of the space where the spinal nerves exit the spinal canal. Realignment may also be appropriate in this case in order to prevent further stenosis occurring. Where central spinal stenosis is in evidence the surgeon is likely to take a posterior approach and remove a portion of the lamina in order to allow the spinal cord and spinal nerves to decompress. This may be a laminotomy, where a small window is cut in the backbone, a laminoplasty, where the lamina is cut on one side to form a hinge held in place by instrumentation, or a full laminectomy where the section of lamina at one or more vertebral levels is removed in its entirety. The more extensive the removal of structural material in the spine, the more likely spinal fusion is to be required.

Where a Gill fragment is present it can press on the spinal nerves and a surgeon may elect to remove the facet joint in a facetectomy procedure. Partial removal of a facet joint may not require spinal fusion, but a full facetectomy, discectomy, or other significant excision of tissue which leaves a ‘gap’ in the spine usually needs fusion to take place to provide stability. Depending on the approach taken, the surgeon will use a combination of metal instrumentation and bone (either taken from the patient or from a bone bank) to join the vertebra into one long bone. In ALIF, TLIF, and PLIF procedures the bone graft is inserted between the vertebra in order to fill the disc space and support the spine from the front to the back. Spinal fusions which fuse only the posterior section of the vertebrae may be put under extra stress if the anterior spine continues to tilt forward.

Back surgery for spondylolisthesis has, traditionally, been a very invasive affair, with muscles and ligaments needing to be cut so that the surgeon can access the spine to carry out the decompression, realignment, and fusion. This increases the degree of trauma, bleeding, bruising, and risk of complication and leads to a long recovery period with extensive rehabilitation requirements. For many patients then, minimally invasive surgery is a preferred option with several smaller incision providing adequate access to the spinal structures, less need to cut muscles or ligaments as these are pushed aside instead, and a swifter recovery for most. Decompression surgeries such as ALIF, PLIF, and TLIF can be performed in a minimally invasive fashion in the majority of cases, but some surgeons may require a ‘mini open’ procedure where they use both traditional and minimally invasive surgical methods to facilitate decompression and spinal fusion.

Continue Reading –> Is Surgery Always Necessary for Spondylolisthesis?