Who is a candidate?
Interbody fusion is considered for instability with nerve compression, spondylolisthesis, degenerative instability, recurrent herniation, or stenosis where movement at the level is demonstrated on flexion and extension X-rays. It is also used where restoring disc height and lumbar curve forms part of correcting alignment. Degeneration on imaging alone, without instability or nerve compression, is not by itself a reason to fuse.
How the procedure works
ALIF approaches the front of the spine through the abdomen, between tissue planes, often with an access surgeon. The disc is removed and a large spacer placed, restoring height and curve without disturbing the back muscles or nerves.
TLIF approaches from behind through the foramen on one side. The nerve is decompressed directly, the disc removed, and a spacer inserted through that corridor. Screws and rods are placed to stabilize the segment while the fusion heals.
Recovery
Walking begins the day of surgery. ALIF often produces less early back muscle soreness, while TLIF allows direct nerve decompression at the same sitting. Bending, lifting, and twisting are restricted while the fusion consolidates. Bone healing continues over several months, and activity is advanced in stages rather than all at once.
Benefits and alternatives
Both restore disc height, indirectly opening the space for the nerves, and stabilize a segment that has become a pain source through movement. Alternatives include decompression alone where the segment is stable, MIS TLIF or prone lateral fusion depending on anatomy and alignment, and continued non-operative care with therapy and injections.
Risks
Risks include infection, bleeding, nerve injury, a tear in the lining around the nerves, hardware problems, and failure of the bone to fuse, which can require further surgery. ALIF adds the risks of the anterior approach, including vascular or abdominal injury and, in men, a small risk of retrograde ejaculation. Adjacent levels may degenerate over time under altered mechanics.