Posterior Lumbar Interbody Fusion (PLIF)

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.

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 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 new technology for treating back pain. 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 the titanium cages are inserted into the disc space. Cage 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, which is currently under FDA investigation, requiring participation in a research study.

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 joints, depending upon the number of levels requiring surgery.

The Surgical Procedure:
Under general anesthesia, an incision 6" to 10" will be made in the back, through the muscles, down to the spine. The lamina will be removed, all or in part (this is the laminectomy part of the surgery), which then allows good access to the vertebral bodies, discs, and nerve roots.

Most of the disc (85% to 95%) will be removed thereby removing pressure from the nerves. A "spacer," bone, or cages, will be inserted into the space between the vertebrae where the disc used to be in order to maintain appropriate room for nerves to exit. Bone will grow through holes in the cages, fusing the vertebral body above the disc to the one below.

If bone is used from the hip or from the bone bank, it will grow together, or fuse, with existing bone. The result is the same in either case: the spine is stable and pressure is taken off the nerves.

Additional posterior stabilization may be used with metal, such as rods and pedicle screws. (The use of hardware or instrumentation is sometimes the best option your surgeon has to obtain the best results. This is a confusing area as there are issues involving how the instrumentations are classified by the FDA. In some instances the indications may differ from the ones on the manufacturer's label. Be sure and ask your surgeon to explain this to you before surgery if you are not clear on the plans.)

The incision is closed and the patient is taken to the recovery room. Surgery for one disc usually takes 2 to 2 ½ hours. Additional levels can take as long as 3 hours total surgery time. Hospital stay is usually 2-3 days.

Potential Risks for a Posterior 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:

1. Pain, numbness, and clumsiness could be experienced after surgery. Manipulation of nerves during surgery may result in inflammation or injury.
2. Impaired muscle function. This refers to weakness or paralysis.
3. 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.
4. Unstable spine. Only the amount of 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.
5. 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.
6. 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.
7. 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.
8. 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.