Anterior Lumbar Interbody Fusion
During ALIF (Anterior Lumbar Interbody Fusion), the disc space is fused by approaching the spine through the abdomen instead of through the lower back. In the ALIF approach, a three to five-inch incision is made on the left side or across the bottom of the abdomen and the muscles are retracted to the side.
Since the anterior abdominal muscle in the midline (rectus abdominis) runs vertically, it does not need to be cut and easily retracts to the side. The abdominal contents lay inside a large sack (peritoneum) that can also be retracted, thus allowing the spine surgeon access to the front of the spine without actually entering the abdomen. Large blood vessels (aorta and vena cava) that continue to the legs lay on top of the spine, so many spine surgeons will perform this surgery in conjunction with a vascular surgeon who mobilizes the large blood vessels. After the blood vessels have been moved aside, the disc material is removed, and bone graft inside of an interbody cage made of plastic, is inserted. 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. This provides for better initial stability of the fusion construct and allows the ability to increase the size of the holes that hold the nerves (indirectly decompressing them).