ANTERIOR LUMBAR INTERBODY FUSION (ALIF)
Spinal fusion is a surgical procedure used to correct problems with the vertebrae. It is essentially a “welding” process. The basic idea is to fuse together the painful vertebrae so that they heal into a single, solid bone.
An interbody fusion involves removing the intervertebral disc. When the disc space has been cleared out, a metal, plastic, or bone spacer is implanted between the two adjoining vertebrae.
In an anterior lumbar interbody fusion (ALIF), the procedure is performed from the front. With this approach, the organs and blood vessels must be moved to the side. This allows your surgeon to access the spine without moving the nerves (AAOS, 2015).
The ALIF approach is advantageous in that, unlike the PLIF and posterolateral gutter approaches, both the back muscles and nerves remain undisturbed.
Another advantage is that placing the bone graft in the front of the spine places it in compression, and bone in compression tends to fuse better.
Lastly, a much larger implant can be inserted through an anterior approach, and this provides for better initial stability of the fusion construct.
TREATMENT & BENEFITS
ALIF is commonly performed for a variety of painful spinal conditions, such as spondylolisthesis and degenerative disc disease, among others.
Fusing provides a high degree of stability for the spine and a large surface area for the bone fusion to occur. Approaching both sides of the spine often allows for a more aggressive reduction for patients who have deformity in the lower back (e.g. isthmic spondylolisthesis).
Some spine surgeons feel that if stabilization is achieved both through an anterior and a posterior approach, patients can be mobilized earlier in the postoperative period. Studies have shown that fusing both sides of the spine in the lower back does lead to a very high fusion rate (greater than 95% of these cases will achieve a solid fusion).
The surgery is performed utilizing general anesthesia. A breathing tube (endotracheal tube) is placed and the patient breathes with the assistance of a ventilator during the surgery. Preoperative intravenous antibiotics are given. Patients are positioned in the supine (lying on the back) position, generally using a special, radiolucent operating table. The surgical region (abdominal area) is cleansed with a special cleaning solution. Sterile drapes are placed, and the surgical team wears sterile surgical attire such as gowns and gloves to maintain a bacteria-free environment.
A 3-8 centimeter (depending on the number of spinal levels to be fused) transverse or oblique incision is made just to the left of the belly button. The abdominal muscles are gently spread apart, but are not cut. The peritoneal sac (containing the intestines) is moved to the side, as are the large blood vessels. Special retractors are used to allow the surgeon to visualize the anterior (front part) aspect of the intervertebral discs. After the retractor is in place, an x-ray is used to confirm that the appropriate spinal level(s) is identified.
The intervertebral disc is then removed using special biting and grasping instruments. Special distractor instruments are used to restore the normal height of the disc, as well as to determine the appropriate size spacer to be placed. A bone spacer (metal or plastic spacers may also be used) is then carefully placed in the disc space. Fluoroscopic x-rays are taken to confirm that the spacer is in the correct position.
The wound area is usually washed out with sterile water containing antibiotics. The deep fascial layer and subcutaneous layers are closed with a few strong sutures. The skin can usually be closed using special surgical glue, leaving a minimal scar and requiring no bandage.
The total surgery time is approximately 2 to 3 hours, depending on the number of spinal levels involved.