Doctor Cloward first performed an anterior lumbar interbody fusion (ALIF) surgery in the 1950s for treatment of lower back pain for degenerative spine conditions. The Cloward procedure did not gain immediate favor because of fairly high nonunion rates (30-40%).
In the 1990s, however, there was a resurgence of popularity for anterior (from the front) lumbar interbody fusion surgery because of the advent of new threaded titanium cages that held the disc space better and allowed for a higher fusion rate.
Modern Applications of ALIF Surgery
While the ALIF is still a widely available spine fusion technique, this type of procedure is often combined with a posterior approach (anterior/posterior fusions) because of the need to provide more rigid fixation than an anterior approach alone provides.
In cases where there is not a lot of instability, an ALIF alone can be sufficient. Generally, this is true in cases of one level degenerative disc disease where there is a lot of disc space collapse.
For patients who have a "tall" disc, or for those with instability (e.g. isthmic spondylolisthesis), an anterior approach to spinal fusion may not provide adequate stability. In these clinical situations, the anterior lumbar interbody fusion may be supplemented with a posterior (from the back) instrumentation and fusion to provide additional support to the fused level of the spine. For more information, see Spinal Fusion Surgery for Isthmic Spondylolisthesis.
Description of Anterior Lumbar Interbody Fusion Surgery
The anterior lumbar interbody fusion (ALIF) is similar to the posterior lumbar interbody fusion (PLIF), except that in the ALIF, the disc space is fused by approaching the spine through the abdomen instead of through the lower back. In the ALIF approach, a three-inch to five-inch incision is made on the left side of the abdomen and the abdominal 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.
There is also a less popular transperitoneal approach that accesses the spine through the abdomen. This adds a lot of unnecessary morbidity to the procedure and therefore is used much less often.
Although previously there was a lot of interest in perfecting an endoscopic approach for ALIF surgery, it has largely been abandoned because it placed the great vessels (aorta and vena cava) at too great a risk.
These large blood vessels 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, or bone graft and anterior interbody cages, is inserted.
Advantages of ALIF Surgery
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.