What it is
Lumbar fusion eliminates motion at one or more vertebral segments by placing bone graft between the vertebrae and using pedicle screws and rods to hold them in position while the graft heals into solid bone. Once fused, the treated levels no longer move — which removes them as a source of mechanical instability but also reduces the overall flexibility of the lumbar spine.
There are several techniques for introducing the bone graft:
- TLIF (transforaminal lumbar interbody fusion) — a posterior approach that also allows disc removal and nerve decompression
- ALIF (anterior lumbar interbody fusion) — approached from the front of the abdomen; provides a larger graft footprint and good lordosis restoration
- LLIF / XLIF — lateral approaches through the flank; minimally invasive access to the disc space
- PLIF (posterior lumbar interbody fusion) — an older posterior approach, largely supplanted by TLIF
The approach is chosen based on anatomy, goals of surgery, prior operations, and surgeon experience.
When fusion is and isn't appropriate
Fusion is appropriate when there is documented instability (as in spondylolisthesis), when decompression alone would create instability, or when the pain generator is clearly a mechanically unstable segment.
It is not appropriate — and outcomes are unpredictable — when done for axial low back pain without structural instability, or when the pain generator is not clearly identified. An honest conversation about what fusion can and cannot be expected to accomplish is an essential part of the preoperative process.
What to expect
Recovery from lumbar fusion is longer than from decompression alone. Most patients go home after two to four days. A period of activity restriction follows to protect the healing fusion. Full fusion maturation takes three to six months, confirmed by imaging. Most patients notice gradual improvement in leg symptoms before back symptoms.