A posterior lumbar interbody fusion (PLIF) surgery involves adding bone graft to an area of the spine to set up a biological response that causes the bone to grow between the two vertebral elements and thereby stop the motion at that segment.

Unlike the posterolateral gutter fusion, the PLIF achieves spinal fusion in the low back by inserting a bone graft and/or spinal implant directly into the disc space. A PLIF fusion is often supplemented by a simultaneous posterolateral spine fusion surgery.