Author: Internet Business Development
Date Posted: 22nd September 2007
Multilevel fusion as a primary treatment for low back pain from degenerated discs is a controversial topic in spine medicine. In certain instances, a two level spinal fusion may be an effective treatment for debilitating back pain from two degenerated lumbar discs.
However, lumbar fusion of three or more levels of the low back as a primary treatment for back pain is rarely recommended, and many surgeons recommend against it in all cases of multilevel degenerative disc disease. Fusion of the spine refers to removing motion around or through a disc space by creating a bone bridge from one vertebra to the next. Fusion can be accomplished through several ways. The most common approaches are:
Interbody fusion. When the fusion is done through the disc space it is called an interbody fusion. The interbody fusion can be accomplished through the front of the spine (anterior interbody fusion), from the side of the spine (extreme lateral interbody fusion, or XLIF), or from the posterior aspect of the spine (transforaminal lumbar interbody fusion (TLIF) or posterior lumbar interbody fusion (PLIF).
Posterior or posterolateral fusion. This approach is done through the back and focuses on connecting portions of the posterior (in the back of the spine) bony elements of the spine. This may also be referred to as a facet fusion. In some cases, both interbody and posterior fusions are performed at the same time. Each type of spinal fusion has specific indications as well as specific risks and benefits.
The lumbar spine (low back) has six mobile spinal levels, also known as motion segments, surrounding and in between the five lumbar vertebrae. A spinal level carries the name of the disc at that level, named by the vertebra above and below the disc. For example, the disc space or motion segment between the L4 and L5 vertebrae is know as the L4-5 disc or the L4-5 level. The lowest spinal segment, between the L5 vertebra and the sacrum bone of the pelvis, is known as the L5-S1 level. At each spinal level,motion is controlled by the disc, between the vertebral bodies, and the paired left and right facet joints, in the back of the spine, which allow flexion and extension motion in the lumbar spine and block rotation motion.
Fusion of only one motion segment of the spine (e.g. L5-S1) is referred to as a single level fusion. Multilevel spinal fusion refers to fusion of more than one spinal disc level. When a multilevel spinal fusion is performed, it is almost always on contiguous spinal levels. The most common levels included in a multilevel spinal fusion are L4-5 and L5-S1.
Indications for multilevel fusions
Multilevel spinal fusion for treatment of low back pain is a controversial topic. In general, lumbar spine fusion has a relatively poor success rate for treatment of multi-level disc degeneration seen on MRI scans1. A two-level fusion may be considered for patients with severe, disabling pain that occurs at two levels of the spine (e.g. L4-L5 and L5-S1) after extensive non-surgical and pain management approaches have been tried.
However, three-level fusions for treatment of low back pain from lumbar degenerated discs are rarely advisable for three main reasons:
Uncertain outcomes. With fusion at three or more levels of the spine, there is a significant risk that the surgery will not improve the patient's pain. Too much rigidity. Three level fusions limit movement and flexibility in the patient's back so much that this in and of itself is likely to cause pain. Adjacent level degeneration. Extensive fusion of the lumbar spine transfers stress to the next level of the spine and puts that level at risk for degeneration. For example, a fusion from L3 through S1 would put the L2-L3 level of the spine at risk for degeneration and causing future pain.
Because of the above, some physicians believe that lumbar degenerative disc disease at three or more levels of the spine means that fusion surgery is not an option. Instead, patients with severe pain and degeneration at three or more levels of the spine are often advised to enter a comprehensive pain management program.
In addition to treatment for severe low back pain, there are many different reasons that surgeons perform multilevel spinal fusions. One common indication is for the treatment of spinal deformity, including scoliosis (side curvature of the spine), kyphosis (forward bending of the spine), and spondylolisthesis (forward slippage of one vertebra on another). In addition, multilevel spinal fusions are often performed in the treatment of the less commonly seen fractures, tumors, and infections of the spine.
Multilevel Fusion Surgery
The surgical techniques involved in multilevel spinal fusions are similar to those of single-level fusions. The 'menu' of potential surgical approaches, bone graft options, and cage and instrumentation possibilities are the same as for one level fusions. This includes posterior approach only, anterior approach only, or a combined anterior and posterior approach surgery, which is more common in multilevel fusions. Most multilevel fusion procedures involve the use of spinal instrumentation in the back of the spine, but may also include supplemental anterior fixation as well.
The addition of multiple levels in the surgery increases the complexity of the procedure somewhat and also increases the risks compared to single-level fusion surgery. Potential problems with blood loss, arterial and venous thrombosis, and post-operative wound infections are directly related to the length of surgery, and multilevel procedures generally take longer than single-level fusions.
However, the risks are not directly additive; a two-level fusion does not have twice the risk of a one-level fusion, but only a few percent increase in risk. Preoperative considerations in multilevel fusion surgery relate to the larger size of the operative procedure. Consideration is usually given to preoperative blood donation, to have the patient's own blood available for transfusion if needed due to the higher blood loss commonly associated with multilevel procedures. One unit of donated blood may be all that is needed if expected blood loss is minimal, and up to 3 units may be recommended in some larger reconstructive procedures. For larger anterior procedures and in high risk patients with a history of blood clots (deep venous thrombosis (DVT) or pulmonary embolus (PE)), use of a preoperatively placed removable filter into the Inferior Vena Cava (IVC filter) may be worth the added risk of the procedure in order to minimize the risk of a postoperative DVT or PE. These issues should be discussed with the treating surgeon as part of the preoperative discussion of surgical risk and ways to minimize these risks.
Recovery after multilevel fusion
Postoperative considerations include a longer recovery overall than for a one-level fusion, as would be expected due to the larger procedure overall. Depending on the surgical technique used, recovery still may be fairly quick, such as 6 to 8 weeks with the use of minimally invasive techniques. When multilevel fusion is done as a large reconstruction for spinal deformity (such as from scoliosis or scheuermanns kyphosis) over 4 levels or more, it can easily take the patient 6 months or more for maximal recovery.
With multilevel fusion procedures, use of a postoperative external brace is common, providing added support and limiting excessive motion of the low back. Use of rigid internal fixation (rods and screws) and interbody fusion support may obviate the need for a postoperative brace, even in a multilevel fusion, especially if a patient's bone quality is strong.
Longer term issues to consider in multilevel fusion surgery include the risk of failure of fusion (also known as nonunion or pseudoarthrosis), as well as the theoretically higher risk of adjacent level degeneration.
Fusion failure of one or more levels in multilevel fusion surgery can occur in as high as 40-50 percent of cases, and is highly dependent on patient risk factors and the surgical technique used. Patient risk factors for fusion failure include being a smoker, history of osteoporosis, and history of prior fusion failure. Surgical techniques to enhance fusion rate include interbody and posterior combined fusion, use of patient's own iliac crest (pelvic) bone graft, and use of growth factors such as BMP-2 or OP-1. Again, the specific surgical technique used and risk of nonunion are subjects for the in-depth preoperative surgical discussion every surgical patient should have with their surgeon.
Mobile spinal levels surrounding a spinal fusion see additional stresses when motion is restricted across the fusion. While it has not been proven, this additional stress is felt to contribute to a higher incidence of degeneration of adjacent segments, which could result in symptoms and the need for additional surgery in the future. This is known as 'adjacent segment disease'. The stress seen by an adjacent level and risk of adjacent segment disease is felt to be progressively higher with more and more levels stiffened by fusion. Therefore, it is thought that multilevel spinal fusions may have a higher risk of adjacent segment disease than single level fusions.
While multilevel spinal fusions are a common and necessary procedure to treat many types of spinal surgical pathology, such as scoliosis or other types of deformity, for treatment of low back pain from degenerative disc pathology this type of procedure remains controversial. For two-level rigid fusions, a full discussion between the patient and spine surgeon should include the reason for the need for multilevel surgery, the added risks, and the surgical technique options in order to minimize risk and maximize chances for relief of symptoms and complete recovery. A fusion of three or more levels of the spine for painful multilevel degenerative disc disease is rarely, if ever, advisable. Patients who may be considering this option should exercise extreme caution by proactively researching all their non-surgical options and seeking additional surgical and non-surgical opinions.