Anterior lumbar fusion has traditionally been performed through a retroperitoneal or trans abdominal approach. In the retroperitoneal approach an incision is made on the side of the abdomen and the spine is exposed in a plane posterior to the peritoneum. This results is less risk of scarring and injury to the bowel. In a transabdominal exposure the peritoneum is entered and the bowel separated to expose the lumbar spine.

More recently, we have performed the procedure in a laparoscopic fashion. This involves placing cameras within the abdomen, which is distended by air. The spine can be visualized on a television monitor and the procedure is carried out working through small portals or tubes placed through extremely small incisions.

Irrespective of the exposure, the procedure is carried out in a somewhat similar fashion. Following identification of the abnormal disc, the iliac artery and vein are mobilized and retracted away from the disc space to avoid injury. The ligaments over the disc are incised and the disc is removed either partially or in its entirely. Cartilage along the surface of the bony end plates is removed.

Following preparation of the disc space, bone graft with or without instrumentation is inserted. There are several sources of bone graft available. Femoral rings taken from cadavers have been used extensively. This type of graft provides excellent structural stability but has been extremely slow to incorporate with development of a fusion. Tricortical iliac crest taken from the patients pelvis incorporates more quickly but lacks the same strength and may be prone to compression prior to fusion.

More recently a number of surgical implants have been developed which provide both structural stability and, by using cancellous bone, incorporate more quickly. These implants have the additional benefit of allowing insertion, in some instances, in a laparoscopic fashion.

Among the more commonly used devices at the present time is the BAK Cage. Following exposure of the disc a channel is cut with removal of disc and bone in a cylindrical fashion. The Cage is actually a hollow, threaded sleeve, which is screwed into the channel. The Cage is filled with cancellous bone, which fuses to the patient’s vertebrae through openings along the surface of the sleeve.

Unlike insertion of femoral rings, insertion of the cages can not be visualized directly and requires flouroscopic imaging to verify appropriate positioning.

Patients are fitted with a lumbarsacral orthosis. This is a two-part hard plastic brace, which is secured by velcro straps. Patients are advised to remain in the brace except when lying flat in bed.