PLIF stands for posterior lumbar interbody fusion, a spinal surgery that removes a damaged disc in the lower back and fuses the two vertebrae on either side of it into a single, stable segment. The goal is to eliminate the motion that’s generating pain. It’s one of the most established fusion techniques, with a 97% rate of successful bone fusion across published studies.
The “posterior” in the name means the surgeon operates through your back, and “interbody” means the fusion device goes directly into the disc space between two vertebrae. PLIF can be performed at any level of the lumbar spine, from L1 down to S1, which gives it broader reach than some alternative approaches that only work well at the lowest one or two levels.
Conditions That Lead to PLIF
PLIF is most commonly recommended for degenerative spondylolisthesis, a condition where one vertebra slips forward over the one below it due to age-related wear on the joints and disc. When that slippage is unstable (generally defined as more than 4 mm of movement or a slip angle greater than 10 degrees), adding an interbody fusion to the procedure improves both function and pain relief compared to simpler operations.
Beyond spondylolisthesis, PLIF is also used for degenerative disc disease that hasn’t responded to conservative treatment, spinal stenosis with instability, spinal deformity, and pseudarthrosis (a prior fusion that failed to heal). In all these cases, the underlying problem is the same: a spinal segment that moves in a way it shouldn’t, compressing nerves or generating chronic pain.
What Happens During the Procedure
You lie face down under general anesthesia. The surgeon makes an incision along the midline of your lower back and moves the muscles aside to expose the vertebrae. The lamina (the bony roof of the spinal canal) is partially or fully removed to create a window into the disc space. This step also decompresses any pinched nerves.
Next, the surgeon removes the damaged disc. A specialized instrument is inserted into the disc space and used to clear out disc material while carefully preserving the endplates, the thin layers of bone on the top and bottom of each vertebra that the new graft needs to grow into. Once the space is cleaned and measured with trial spacers, two interbody cages (small, hollow implants) are inserted through the opening, one from each side.
These cages are packed with bone graft material to encourage new bone to grow through and between the vertebrae. Finally, pedicle screws are placed into the vertebrae above and below the disc space, connected by rods, to hold everything stable while the fusion solidifies over the following months.
Bone Graft and Cage Options
The cage itself is typically made from PEEK (a biocompatible polymer introduced in the 1990s) or titanium. Studies comparing PEEK, titanium, and carbon fiber cages have found no significant difference in clinical or radiological outcomes, so the choice often comes down to surgeon preference and the specifics of your anatomy.
What goes inside the cage matters just as much. The gold standard is autograft, bone harvested from your own body, most commonly from the iliac crest (the top of your hip bone) or from bone removed during the decompression portion of the surgery. Autograft has the advantage of containing your own living bone cells. When autograft isn’t available or sufficient, surgeons use allograft (donor bone from a cadaver or living donor) or synthetic bone substitutes. One study comparing allograft to iliac crest autograft inside PEEK cages found fusion rates of 80% and 85% respectively, with no statistically significant difference.
How PLIF Compares to TLIF
TLIF, or transforaminal lumbar interbody fusion, is the procedure most often discussed alongside PLIF. Both approach from the back, but they differ in a meaningful way. PLIF accesses the disc space through the spinal canal, which requires the surgeon to retract the nerve sac and nerve roots to both sides. TLIF comes in from an angle through the side of the spine, removing one facet joint entirely to create a pathway that largely avoids the nerve sac.
This difference gives TLIF a lower risk of nerve injury and dural tears (punctures to the membrane surrounding the spinal cord). TLIF also preserves more of the bone and ligament structures on the opposite side, leaving additional surface area for fusion. Because PLIF requires working on both sides of the disc space, it sometimes involves removing portions of both facet joints, which can create more immediate instability, particularly when two levels are fused at once.
PLIF does have advantages in certain situations. It allows the surgeon to place two cages symmetrically, which can provide balanced support across the disc space. For some anatomies and pathologies, the direct posterior view gives better access. Your surgeon’s recommendation will depend on your specific condition, the number of levels involved, and their experience with each technique.
Success and Fusion Rates
PLIF has the highest fusion rate among common lumbar fusion techniques. A review of modern lumbar fusion methods found that 97% of PLIF patients achieved solid bone fusion (155 out of 159 cases). That was significantly better than posterolateral fusion alone, which achieved 84%. Solid fusion matters because studies with seven-year follow-up have shown that patients who develop pseudarthrosis (failed fusion) have worse pain and functional outcomes over time.
Recovery After PLIF
Hospital stays vary depending on your age and overall health. For first-time elective posterior lumbar fusions in elderly patients, the average stay is longer, but most younger, healthier patients can expect to be discharged within a few days.
The early weeks of recovery focus on walking and basic movement. Most surgeons impose lifting restrictions, typically around 10 kg (roughly 22 pounds) for the first several weeks, to protect the fusion while it heals. You’ll also be advised to avoid bending and twisting at the waist. These restrictions are based on clinical experience rather than strict scientific protocols, and they vary somewhat from surgeon to surgeon.
Returning to work depends heavily on what your job involves. Data from lumbar interbody fusion patients shows that 75% return to work within three months. Sedentary or office jobs allow an earlier return than physically demanding roles, which may require four to six months or more. The bone fusion itself continues to mature and strengthen for up to a year after surgery, even after you’ve resumed most normal activities.
Risks and Complications
The most discussed risk specific to PLIF is nerve injury, which stems from the need to retract the nerve sac and nerve roots during the procedure. Dural tears, where the protective membrane around the spinal cord is nicked, are another recognized complication. Both occur at low rates in experienced hands but are more common with PLIF than with TLIF due to the approach.
General surgical risks apply as well: infection, blood loss, blood clots, and anesthesia-related complications. Hardware-related issues, such as screw loosening or cage migration, can occur but are uncommon with modern instrumentation. The risk of needing a revision surgery increases when multiple levels are fused, since removing more bone and disc material places greater mechanical demands on the hardware and remaining structures.