A lumbar fusion approached from the front, through the abdomen, rather than through the back muscles. The disc is removed completely and a large graft is set directly against the endplates — the biggest interbody footprint of any approach, and the best at restoring lost disc height and the natural curve of the lower back. The back muscles are never touched.
Reaching a lumbar disc from behind means working around the nerves — they sit between the surgeon and the disc, so the corridor is a window beside them and the graft has to fit through it. Reaching the same disc from the front means the nerves are on the far side of it. Nothing neural is retracted, and the disc is exposed across its entire width.
Two things follow. The disc can be removed completely, including the front portion that a posterior approach cannot reach, which leaves more raw bone surface for the fusion to take on. And the graft can be as large as the disc space itself, resting on the dense bone around the rim rather than on the softer bone in the middle.
That size is what gives ALIF its particular strength: a tall graft placed at the front of the disc space props the front of the segment open, which is exactly how the lower back regains its forward curve.
ALIF construct at L5–S1. Lateral view of the anterior interbody graft seated against prepared endplates, showing restored disc height and segmental lordosis, with the foramen opened compared with the collapsed pre-operative state.
It is chosen when the goal of the operation involves height and alignment, not only stability — and it is chosen especially often at the bottom of the lumbar spine.
The bottom disc of the lumbar spine sits deep in the pelvis, tipped steeply forward. That geometry makes it awkward to reach from the side — the iliac crest is in the way, which is why a lateral approach cannot get to L5–S1 at all. From behind it is reachable but the angle is unfavourable for restoring lordosis, because the graft goes in from the back of a space that needs propping at the front.
From in front, that same steep angle becomes an advantage: the disc faces the surgeon almost squarely, and the vessels have usually divided above it, leaving a natural window down onto the disc. L5–S1 is the level ALIF suits best.
This is why a construct spanning several levels is sometimes done through two corridors — lateral for the levels above, anterior for L5–S1. Using the best corridor for each level is a plan, not a complication.
The route to the front of the lumbar spine passes behind the abdominal cavity, so the bowel is moved aside rather than opened. What lies directly over the disc, however, is the body’s largest blood vessels — the aorta and vena cava and the iliac vessels they divide into. They have to be carefully mobilised to one side to expose the disc.
For that reason the approach is commonly performed together with an access surgeon — a vascular or general surgeon who opens the corridor and looks after the vessels while the spine surgeon does the fusion, then closes it afterwards. Two surgeons, each doing the part they do most often, is the standard arrangement for this operation and is a safety measure rather than a sign of difficulty.
The same level, reached from opposite directions. The comparison is against MIS TLIF, which is the more commonly performed of the two.
Both are operations Dr. Zaidi performs and both are minimally invasive in the sense that matters — neither strips the back muscles the way an open posterior fusion does. Where the canal itself needs opening, a posterior decompression is required and ALIF alone will not do it. See how the approach is chosen.
The patient lies on their back. Imaging confirms the level and the working angle onto the disc before the incision.
A short transverse incision low on the abdomen. The plane behind the abdominal cavity is developed so the bowel is swept aside rather than entered, and the great vessels are identified and gently mobilised to expose the disc.
The disc is removed across its full width and depth — including the anterior portion no posterior approach can reach. The endplates are prepared back to bleeding bone without breaching the strong plate that will carry the graft.
Trials establish the height that opens the foramina and the angle that restores the segment’s lordosis. The chosen implant, packed with graft, is seated against the rim of the endplates where the bone is strongest.
The construct is secured — with screws through the implant into the vertebrae above and below, or with pedicle screws placed posteriorly, depending on stability, bone quality and what is being corrected.
The vessels are returned to their position and confirmed to be pulsatile and intact, and the abdominal wall is closed in layers.
Anterior lumbar interbody fusion. The retroperitoneal corridor, the great vessels mobilised, complete discectomy and endplate preparation, and a lordotic implant seated at the front of the disc space with height and curve restored.
Every fusion shares the general risks of surgery. Two belong to this corridor specifically and are discussed as part of consent:
Figures are general ranges from the surgical literature, not guarantees for any individual case. The recovery has a different shape from a posterior fusion: the back itself is comparatively comfortable early on, while the abdomen takes a few days to settle and lifting is restricted while the abdominal wall heals. Follow the instructions you are given after your own operation rather than these.
Whether the front is the right corridor for your level depends on what needs restoring as well as what needs stabilising. Bring any MRI or CT you already have — most of the question is answered before the conversation starts.