Interbody Fusion (TLIF/XLIF/ALIF)

What It Is

Spinal fusion is a surgical procedure used to correct problems with the small bones in the spine (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 disk. When the disk space has been cleared out, a metal, plastic or bone spacer is implanted between the two adjoining vertebrae.

These spacers, or “cages”, usually contain bone graft material. This promotes bone healing and facilitates the fusion. After the cage is inserted, surgeons often use metal screws, plates and rods to further stabilize the spine.


An interbody fusion can be performed using a variety of different approaches.

Anterior Lumbar Interbody Fusion (ALIF). In an ALIF, the procedure is performed from the front. With this approach, the organs and blood vessels must be moved to the side. This allows the surgeon to access the spine without moving the nerves.

Transforaminal Lumbar Interbody Fusion (TLIF). When a posterior spinal fusion is required, such as for a spondylolisthesis (slippage of the spine), tumors or trauma, there are many techniques a surgeon can employ to create a solid fusion of the lumbar spine bones. One of these techniques, TLIF, is performed through a posterior incision over the patient’s lumbar spine. The surgeon takes down the bone that covers the spinal canal and moves the spinal cord out of the way to get to the space between the two lumbar vertebrae. The surgeon takes out the soft disc material between the two bones and places a cage (a device to hold bone graft) between the two bones. This cage, along with the bone graft, will promote the fusion of the two bones to stabilize the spine. This procedure can be performed in an open technique or using a minimally invasive technique.

Extreme Lateral Interbody Fusion (XLIF). XLIF is a relatively new technique used to promote fusion between two vertebral bodies. It is a minimally invasive procedure compared to the traditional open procedure which involved a large incision on the patient’s side or chest wall. The procedure is performed with the patient in the lateral position on the operating table. Using X-ray to guide his incision, the surgeon inserts a small tube from the patient’s side down to the spine. The procedure is then performed through this tube. Using X-ray and direct visualization with a microscope, the surgeon removes the disc material between the vertebral bodies and places a cage with bone graft to cause the two vertebral bodies to fuse into one bone. After the procedure, some patients may experience pain or weakness in their ability to flex their hip; however, most of these side effects are gone within days to weeks of the procedure.


Minimally invasive surgery is a relatively new term to surgery in the past 10 to 15 years. There have been advancements in all surgical subspecialties with regard to less invasive surgery due to a variety of tools. General surgeons were the first to develop minimally invasive techniques, which included laparoscopic surgery (using a camera and several small probes through tiny incisions in the abdomen). Urologists have made great advances with the use of the robotic assisted surgery. Spine surgery itself has had some great advances over the past 10 to 15 years with the advent of the intra-operative microscope, which allows for very small incisions over the neck and lumbar spine for certain procedures. There has been the development of the extreme lateral approach (XLIF) through tiny incisions to help stabilize the spine with an interbody fusion. The development of kyphoplasty for compression fractures was an advancement in minimally invasive surgery to stabilize osteoporotic compression fractures in the elderly through incisions that are not much larger than a needle stick. All of these procedures can be very useful when used appropriately. They are not indicated for all types of spine surgery. Some spine surgery needs the traditional approach, which has the best studied results and outcomes. The use of minimally invasive techniques is a decision that must be made with both the patient and surgeon.