Anterior Lumbar Interbody Fusion (ALIF)

What it is and why we do it

An anterior lumbar interbody fusion, or ALIF, fuses one or two of the lowest levels of the spine, L4-L5 and L5-S1, through an incision in the lower abdomen. The disc is removed completely and replaced with a large spacer filled with bone graft, usually held with small screws built into the spacer. Because the front of the spine is where the disc is widest, this approach lets me restore disc height and the natural inward curve of the low back better than any approach from the back.

I use it for a painful worn disc at L5-S1 or L4-L5, for a slipped vertebra, for a failed previous fusion, and as the first step of a larger operation to correct adult deformity or flat back. It is the same route used for a lumbar disc replacement.

What happens during surgery

You lie on your back under general anesthesia. A surgeon who specializes in abdominal access makes the incision, usually a few inches long below the navel, and works beside the abdominal contents, not through them, to reach the front of the spine. The large blood vessels that run in front of the spine are gently moved aside and protected. I then remove the disc, release tight tissue, place the spacer, and confirm the position with X-ray. If screws are also needed in the back, they are placed the same day or at a second stage.

Your recovery

Most people stay one or two nights. Walking begins the day of surgery or the next morning. Two things are expected after an anterior approach and are not signs of trouble: the bowel is slow for a few days, so we start with liquids and advance your diet slowly, with a bowel plan from the first day; and bruising of the abdominal wall, and in men swelling of the scrotum, can appear in the first week and fade on their own. A warmer or "different-feeling" leg on one side is also common for a few weeks, from the nerves that control blood vessel size being moved during the approach.

Activity and restrictions

Walk often. For about six weeks, avoid bending at the waist, lifting more than 10 to 15 pounds, and twisting, and avoid long stretches of sitting. No baths, pools, or soaking for six weeks. Driving resumes when you are off narcotics and comfortable, often around three to four weeks. Desk work often restarts in three to six weeks. The fusion itself takes months to become solid, and I follow it with X-rays. Stopping nicotine in every form is one of the most important things you can do for your result.

Risks that are specific to this approach

Every spine operation carries general risks, which we review together. The front approach adds a few of its own: injury to the large blood vessels, which is uncommon and is the reason an access surgeon is part of the team; injury to the ureter or bowel, which is rare; a hernia at the incision; and, in men at L5-S1, a change in ejaculation called retrograde ejaculation, which affects fertility but not sexual function and is sometimes permanent. The risk of a blood clot in the leg is a little higher after any abdominal surgery, so walking early and the measures we use in the hospital matter.

The science: for the curious

The front of a lumbar disc is wider and better supplied with blood than the back, and the vertebral endplates are strongest at their rim. A spacer placed from the front rests on that rim, which lowers the chance of sinking and gives the largest surface for bone to grow across. Releasing the tight ligament along the front of the spine and placing a wedge-shaped spacer restores lumbar lordosis, the inward curve that lets you stand upright without effort, and this is why ALIF is so often the first stage when a flat or tilted spine is being corrected. Fusion rates at L5-S1 with a front approach are among the highest of any lumbar fusion technique.

Learn more

OrthoInfo, Spinal Fusion: orthoinfo.aaos.org (opens in a new tab)

My guide to lumbar disc replacement uses the same approach to the front of the spine, without a fusion.

This handout is general education about this procedure and does not replace the specific plan, risks, and consent discussion we have together. Your own situation may differ: if anything here does not match what we talked about, what we talked about wins, so please ask me.