If a patient with serious, long-term low back pain is not helped by nonoperative programs, a surgical procedure might be considered. One such procedure is Anterior Lumbar Interbody Fusion (ALIF). The following article provides a basic introduction to the ALIF procedure.

Spinal fusion for the management of lumbar degenerative disc disease has been available for several decades. The results of this procedure remain under constant scrutiny and progressive development. Anterior lumbar fusion was initially introduced in the early 1920s. Fibula and iliac struts, femoral rings and dowel, as well as synthetic metallic devices have been applied as fixation implements to aid in lumbar interbody fusion. Approaches to the spine have experienced similar evolutionary changes. Prior to the 1950s most anterior lumbar approaches were extensive transperitoneal exposures (i.e. through the membrane lining the walls of the abdominal and pelvic cavities). In 1957, Southwick and Robinson introduced the retroperitoneal approach (i.e., behind the peritoneum). Transperitoneal exposures (i.e., through the peritoneum) require incision of both the anterior and posterior peritoneum. In contrast, retroperitoneal expoures maintain the integrity of the peritoneum and approach the spinal column laterally behind the bowel and peritoneal contents. This has the advantage of less post-operative bowel problems. Additional changes in technique have seen the advent of minimally invasive approaches, including endoscopic and laparoscopic methods. Minimally invasive approaches are generally directed at one or two-level disease processes. Anterior lumbar interbody fusion (ALIF) may be useful in the treatment of unyielding low-back pain. The cause of this pain is often difficult to diagnose. Broad categories of pathology that may be associated with persistent low-back pain include degenerative disc disease, spondylolysis, spondylolisthesis or iatrogenic segmental instability.

MRI of patient with disc and vertebral endplate
Perhaps a candidate for a ALIF procedure

ALIF should only be considered following the patient's unsuccessful completion of an organized nonoperative rehabilitation program. Aids to diagnosis in the case of a patient with mechanical low-back pain expand upon a thorough history and physical examination. Radiographic studies; plain films, bone scan (SPECT), CT scan, MRI and discography, all play a role in patient evaluation. Frequently more than one of these diagnostic studies is needed for an accurate diagnosis. ALIF may be utilized as an isolated procedure or in conjunction with posterior spinal fusion. The method with which ALIF is accomplished depends largely on the surgeon's preference and experience. Minimally invasive techniques - open or laparoscopic - require greater intraoperative attention to detail and preoperative surgical planning.

Indications for ALIF Degenerative Disc Disease
The suspected lumbar level requires confirmation as a pain generator by diagnostic testing. Multilevel disease, i.e., greater than two levels of the spine, is less predictable and therefore rarely indicated for ALIF. We have found that single-level disease in a psychologically stable patient, responds well to ALIF.

Spondylolysis and Spondylolisthesis
The vast majority of patients with spondylolysis or spondylolisthesis do not require surgery. Patients with spondylolysis or spondylolisthesis (grade I) may be effectively treated with ALIF as an isolated procedure. Present data is inconclusive regarding the effectiveness of isolated ALIF in grade II spondylolisthesis. Furthermore, biomechanical data related to the degree of vertebral translation concomitant with grade III or greater spondylolisthesis implies that isolated ALIF may be associated with a high pseudoarthrosis rate (failure of fusion). Therefore, in grade III or greater spondylolisthesis, a posterior fusion in addition to ALIF is strongly recommended. ALIF as the only procedure (i.e. without a posterior operation), is not recommended in a spondylolesthesis above grade I.

Iatrogenic Segmental Instability
Hypermobility of a lumbar-motion segment requires rigid fixation to improve fusion rate. Limited sagittal translation may be addressed by isolated ALIF. As inferred above, high degrees of translation are difficult to stabilize; therefore circumferential fusion is often required.

Surgical Technique
While the technique is both skilled and complex, it can be explained in three basic phases:

1) Pre-operative Templating Before the surgery, the surgeon will refer to various MRI and CAT scans of the patient to determine what size implant(s) the patient will need. The implant(s) are used to help promote fusion of two vertebra in the spine.

2) Preparing the Disc Space After the patient is positioned on the OR table and carefully prepared for the surgery, the surgeon begins the procedure. Some of the disc and anaulus is carefully removed, thus preparing the disc space for insertion of the implant(s).

3) Implants Inserted After correct preparation of the disc space a dowel or other implant will be inserted, to promote fusion of the two adjacent vertebra.