Minimally Invasive Posterior Lumbar Interbody Fusion (PLIF): A Beneficial Union

Posterior lumbar interbody fusion (PLIF) is a surgical technique for placing bone graft between adjacent vertebrae (interbody). Typically, screws and rods or other types of spinal instrumentation are used to hold the spine in position while the bone heals. Indications for this procedure may include pain and spinal instability resulting from spondylolisthesis, degenerative disc disease, or when a discectomy is performed to relieve nerve compression and the patient has associated mechanical low back pain.

Spinal fusion uses bone graft to promote specific vertebrae to grow or fuse together into a solid and stable construct. Instrumentation, also called internal fixation, incorporates the use of rods, screws, cages, and other types of medical hardware to provide immediate stability to the spine and facilitate fusion.

Minimal Access Spinal Technologies
Today, spinal surgery has advanced to a new level that utilizes Minimal Access Spinal Technologies (MAST). These technologies replace traditional open surgical procedures with innovative minimally invasive techniques and tools. To grasp the importance and benefits of minimally invasive spine surgery, review the following comparison:

Open Approach
A longer incision along the middle of the back is necessary. Large bands of muscle tissue are stripped from the underlying spinal elements including the spinous process, lamina, and facets. These tissues are pulled aside (retracted) during surgery to provide the surgeon a good view of the spine and room for performing the procedure. During complex spine surgeries, these surrounding tissues (paraspinous) may need to be retracted for long periods of time. Stripping the paraspinous tissues and retracting them can contribute to post-operative pain and prolong the patient's recovery.

Minimally Invasive Approach
In minimally invasive procedures, the surgical incisions are small, there is no need (or minimal need) for muscle stripping, there is less tissue retraction, and blood loss is minimized. Special surgical tools allow the surgeon to achieve the same goals and objectives as the open surgery while minimizing cutting and retracting of the paraspinous muscles. Therefore, tissue trauma (injury) and post-operative pain are reduced, hospital stays are shorter, and patients can recover more quickly.

Open PLIF Procedure
A typical PLIF procedure involves an open incision (approximately 6 inches long) in the middle of the lower back followed by stripping the paraspinous muscles away from the spine. Bone removal (laminectomy) and lumbar discectomy are performed to remove pressure from affected spinal nerve roots. When the offending disc is removed an empty space is left between the upper and lower vertebrae (interbody). This is filled with bone graft. Implants made of bone, metal, or other materials are typically inserted into the interbody space. Finally, pedicle screws are placed into the upper and lower vertebrae and connected with rods or plates.

MAST PLIF Procedure
Now spine surgeons can combine three innovative spinal surgical "systems" with Minimal Access Spinal Technologies (MAST). The combination of these systems allows a PLIF to be performed through two one-inch incisions on either side of the low back. The paraspinous muscles do not need to be stripped from the spine. The spine surgeon can perform bone removal, a discectomy, an interbody fusion, and pedicle screw insertion through the same small incisions!

METRx is a microsurgical system that uses tubes inserted via small skin incisions to work through the normal tissue spaces that separate muscle fibers. These tubes are made to dilate the tissue spaces sequentially, thereby eliminating or minimizing the need for muscle stripping or cutting. The PLIF procedural steps of bone removal, discectomy, and bone graft / interbody implant placement are carried out through the METRx tubes.


TANGENT? is an implant and instrument system used to prepare the interbody space for insertion of precision-machined wedges of cortical bone (bone graft implants).


CD HORIZON® SEXTANT? is a "percutaneous" (through the skin) pedicle screw and rod insertion system. It enables the surgeon to precisely implant the screws and rods in a minimally invasive fashion. Once the METRx tubes have been removed, the SEXTANT? screws are placed through the same small (one-inch) incisions. The rods are percutaneously inserted through tiny openings (approximately one-fourth of an inch long) in the skin. This system helps to immobilize the spine (internal fixation) so the bone grafts can heal and fuse the vertebrae together.


Advancements in spine surgery continue to evolve, providing surgeons with better tools and techniques to treat patients with spinal disorders. We can only expect further improvements as spine specialists continue to adopt and develop emerging technologies and integrate them into their practices.

To learn about Dr. Foley’s practice, click here.

Updated on: 10/18/16
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