What it is
Lateral lumbar interbody fusion (LLIF — also called XLIF or DLIF depending on the specific system) approaches the lumbar spine from the patient's side. The patient is positioned on their side, and a small incision is made in the lateral flank. Working through the retroperitoneal space and passing through the psoas muscle — guided by real-time neuromonitoring to avoid lumbar plexus nerves — a corridor to the disc is established. The disc is removed and a wide interbody cage is placed spanning the disc space from side to side.
Advantages of the lateral approach
- Minimally invasive — no posterior muscle stripping, no need to enter the abdomen
- Large implant — the cage spans the full width of the disc space, maximizing graft contact area and improving fusion rates
- Indirect decompression — restoring disc height through the lateral approach can open the neural foramina and partially decompress nerve roots without directly touching them, which is effective for foraminal stenosis
- Multiple levels possible — multiple disc levels can be addressed through one or two small lateral incisions
- Applicable in revision cases — avoids posterior scar tissue entirely
The lateral approach does not reach L5-S1 due to iliac crest anatomy — that level requires ALIF or a posterior technique.
Neuromonitoring
Passage through the psoas muscle requires careful navigation around the lumbar plexus nerves running within it. Continuous electromyographic (EMG) neuromonitoring guides the approach in real time, identifying proximity to motor nerves before instrumentation. Transient thigh numbness or weakness from psoas and plexus retraction is the most common complication and resolves in most cases.
What to expect
LLIF is typically combined with posterior percutaneous screws for full fixation. Hospital stay is generally two to three days. Most patients notice an improvement in the incision profile and recovery speed compared to open posterior fusion — though the overall recovery from lumbar fusion (fusion healing, activity restrictions) applies regardless of approach.