A posterior lumbar interbody fusion, or PLIF is performed to remove a worn out, or degenerated intervertebral disc with the goal of permanently fusing or “connecting” the surrounding spinal bones, called vertebrae. It is called a posterior procedure because the spine is approached through an incision on the back, and the word “interbody” means the space between the vertebral bodies.
Using a less or minimally invasive surgical technique, this procedure can be done with a smaller incision than traditional open spinal surgeries that use a larger incision and may help avoid disrupting or damaging the low back muscles.
A short incision is made at the midline of the lower back. A device, called a fluoroscope, that projects live x-ray images onto a screen is typically used to help pinpoint the position on the spine where the surgery will be performed. Once the necessary location in the spine is exposed, your surgeon places a device called a retractor into the incision to hold the soft tissue out of the way and allow him/her to see the surgical site during the procedure.
Next, the vertebrae are prepared for the insertion of spinal implants. Either a drill or a sharp instrument called an awl is used to make holes in the bones connecting the back of the vertebrae to the vertebral bodies in the front of the spine. These bones are called pedicles, and the instrumentation placed into them are called pedicle screws. These screws may be placed into the vertebrae above and below the removed disc on both sides of the spine. For a single level posterior lumbar interbody fusion, this means four screws are placed, two on each side. With the screws in place, your surgeon can now move on to the discectomy, or intervertebral disc removal.
Cutting instruments are used to remove portions of the spinal bones called laminae and facets as needed from the back of the vertebrae on each side to allow your surgeon to see the degenerated intervertebral disc. These removals are called laminectomies and facetectomies. The disc space is spread apart by inserting a spreader or by applying pressure between the pedicle screws using a device called a distractor. Your surgeon will then use surgical instruments to remove the intervertebral disc. He/she will then place one or two pieces of donor bone or implant(s) made of metal or plastic and filled with natural bone material between the vertebrae to help add stability and aid in the fusion process over time.
To help provide stability to the spine while the fusion occurs, rods are inserted between the upper and lower screws on both sides to connect them. A device called a compressor can be used to squeeze the upper and lower vertebral bodies together, which can help allow for a tight fit of the implants in the disc space. This pressure, called “compression,” is intended to aid in the spinal fusion process. Small screws called blockers are then inserted to tighten the screws and rods in the compressed position.
Your surgeon will close the incision and dress it with a wound covering at the conclusion of the surgery. Some patients require a brace for a short period of time after surgery.
A minimally invasive surgical, or “MIS” approach can be performed with potentially less operative blood loss and shorter hospitalizations than traditional open surgery.
As with any surgery, spinal surgery carries certain risks. Your surgeon will explain all the possible complications of the surgery, as well as side effects.
