Anterior Lumbar Interbody Fusion (ALIF)
Anterior = From the front
Lumbar = Low back, involving one or more of the last 5 intervertebral discs.
Interbody = Into the disc space.
Fusion = Setting up conditions for added bone to grow to existing bone.
Indications For Spine Fusion:
Normal aging or trauma may cause changes in the bones and discs in the vertebral column, leading to a cascade of conditions that can affect nerve roots. This may cause back pain and sometimes nerve damage.
- A fusion may be considered when your diagnosis is degenerative disc disease, internal disc disruption, or unstable spine.
- An unstable spinal column allows one vertebral body to slip forward or backward above or below adjacent vertebra. This movement narrows the foramen, putting painful pressure on nerve roots. If the spine is unstable, a fusion will promote stability and problems with curvature of the spine may be corrected.
- A problem inside the disc, Internal Disc Disruption, causes pain in the spine; this is believed to be due to leakage of irritating chemicals from the disc.
- Back pain may be a primary complaint, and may be accompanied by hip and leg pain.
- The interbody fusion may also be indicated when there is residual back pain after surgical removal of a disc herniation.
Advances In Spine Fusion Technology
Research has resulted in a new technology for treating back pain. Most notable is the “cage” device used in spine fusions. There are a number of threaded titanium cages approved by the FDA that offer the following advantages over previous fusion techniques:
- Cages are made of titanium, a light-weight, strong metal that is rarely rejected.
- The procedure is less invasive, thereby reducing recovery time and providing greater pain relief. It may be possible to do this with a laparascope.
- Cages restore the disc space to near its original height, thus relieving pressure on nerve roots.
- The threaded aspect of the cage provides instant stability while the bone grows to complete the fusion.
- Return to activity is sooner, and activity levels are significantly increased.
- There is an overall lower complication rate.
How Cages Are Used During Surgery
During surgery, most of the painful disc is removed and titanium cages are inserted into the disc space.
Case size is selected to restore normal disc height in order to take pressure off compressed nerves. One of several substances may be placed inside the cages–your own bone (taken from the iliac crest of your hip), bone bank bone (donated bone), or bone morphogenic protein (a bone growth stimulating protein).
As bone grows through the holes in the cage, fusion occurs, joining the vertebral bodies above and below. This results in a single joint rather than the previous one or two joins, depending upon the number of levels requiring surgery.
- Under general anesthesia, a vascular surgeon will make an incision several inches on the left side and pull the contents to the right. This allows good view and access to the spine.
- Most of the disc is removed, taking care not to go too deep. If the herniated disc is at the back, toward the canal, it can be reached if it is not too big.
- Then comes the “fusion” part of the surgery:
Something will be put in the space where the disc was. Either:
- Bone for the fusion– your own, harvested from your hip, or bank bone—shaped to fit the space. or,
- Holes will be drilled into the disc, overlapping into the vertebral bodies above and below. A cage device will be inserted into the disc space. Bone or material to enhance bone growth will be inserted into the cage. When bone grows though the holes in the cages uniting with the vertebral bodies, the fusion is solid. The advantage of this method is that it provides instant stability—it will not slip. Your doctor will discuss which method is best for you.
- The neurosurgeon has finished his part of the surgery; the vascular surgeon closes the incision.
Risks And Potential Complications Of An Anterior Lumbar Interbody Fusion
It is important to understand that this is major surgery; that is why you want to get better without surgery if possible. If pain is interfering with your life so that you cannot live your life in an acceptable way, then it is o.k. to consider surgery. Surgery is not dangerous, but it is not safe either. It is a little bit like driving in rush-hour traffic. If you are not willing to consider the risk, then surgery should not be considered.
What Are The Risks For A Fusion?
Complications are rare, but they do occur. There is always risk with any surgery, and you need to be aware of possible risks and complications.
Before surgery, you will sign a “consent and disclosure” form stating that the risks have been explained and that you understand what surgery will be performed, and that you wish to proceed with the surgery. Listed will be 8 potential complications:
- Pain, numbness, and clumsiness could be experienced after surgery. Manipulation of nerves during surgery may result in inflammation or injury.
- Impaired muscle function. This refers to weakness or paralysis.
- Incontinence or impotence. This refers to bowel, bladder, or sexual functions. These are uncommon, but may occur as a result of inadvertent injury to the spinal cord or nerves.
- Unstable spine. Only the amount or bone necessary to remove pressure on nerves is removed. Sometimes the amount of bone to free the nerve is enough to cause weakness or instability of the spine. If there is not enough bone left to provide the appropriate amount of stability, it might be necessary to do a spinal fusion, a more extensive surgical procedure to reconstruct weakness in the bones.
- Recurrence of continuation of pain. Symptoms may not go away even if the surgery is done perfectly. There is a possibility that a disc that has been removed might rupture again. This occurs 10 – 15% of the time, even though it can be years later.
- Injury to major blood vessels. The area in front of the vertebral column is immediately adjacent to the major large arteries and veins that come from the heart to supply the organs in the lower part of the body. It is extremely rare, but it is possible for a surgical instrument to go beyond the annulus in the front part of the spine and injure one of these vessels. If that were to occur, we would be dealing with an internal hemorrhage situation and we would need to do an immediate operation from the front side to correct it.
- Leakage of spinal fluid requiring re-operation. The dura is the hard covering of the nerves and spinal cord. Underneath the dura is the spinal fluid surrounding the nerves. If a hole is accidently placed into the dura, then the spinal fluid would be allowed to exit this area. If that occurs while we are in surgery, then it is a fairly simple matter to place a stitch through the small tear and close the opening so that fluid can no longer exit. However, occasionally either the stitches will not hold, or there could be a small recognized tear, and leakage could occur. If that should happen, we may have to take you back to surgery and do another operation to sew up the hole in the dura. Usually this is not a major complication, but you need to be aware of this so that if it does occur it will not be a major shock or surprise to you.
- Complications with bank bone. Bank bone is prepared under very rigid and elaborate conditions to make it extremely safe. It is used routinely in our hospital and throughout the country. The safety record is very good. There remains a very small possibility that a disease could be transmitted with the bone graft. It is also possible for any bone graft to fail to fuse properly.
Additional Risks Include:
- Formation of a blood clot in the wound that may require re-operation.
- Infection which may require further surgeries and long term IV antibiotics.
- Risk of poor healing or movement of the graft, or failure to fuse properly.
- There can be problems with the bone graft harvest site, resulting in numbness along the lateral leg or pain in the area the graft is taken.
- Ancillary risks include blood loss, infection, and discomfort.
- Migration of implants.
Risks Specific To The ALIF Include:
- Sympathetic dysfunction could manifest as a problem for a very small percent of men. Retrograde ejaculation is a condition in which ejaculation goes into the bladder rather than externally. It may be self-limiting.
- If blood vessels in front of the spine are injured, bleeding complications could be encountered which could lead to a significant loss of function in one or both legs.
- The most common sympathetic dysfunction is a feeling of warmth or uncomfortable sensations in one or both legs.
- There is a risk of infection, poor healing, or movement of the bone graft.
- There can be problems with the bone graft harvest site, resulting in numbness along the left lateral leg or hip pain.
- Bowel function should recover while in the hospital. An ilius, or bowel obstruction, is rare, but could require re-operation.
- Ancillary risks include blood loss, infection, and discomfort.
There Are 4 Possible Outcomes From Any Surgery
- Your symptoms or pain may be completely improved.
- Your symptoms or pain may be partially improved.
- Your symptoms or pain may be the same as before surgery.
- Your symptoms or pain may be worse than before surgery.
- Please discuss any concerns with your physician.
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