Posterior Lumbar Interbody Fusion (PLIF) and Transforaminal Lumbar Interbody Fusion (TLIF) are two types of spinal fusion surgeries that fuse (mend) the lumbar spine bones together utilizing a posterior (back area incision) method (using an interbody fusion technique). The intervertebral disc is removed and replaced with a bone spacer (metal or plastic may also be utilized) utilizing a posterior approach in interbody fusion. When one or two spinal levels are fused, the posterior method is frequently utilized in conjunction with posterior decompression (laminectomy) and instrumentation (metal screws/rods). The procedures for posterior interbody fusion are divided into two categories. The typical PLIF surgery involves putting two tiny bone graft spacers on each side of the interbody space, with moderate retraction of the spinal nerves and neurologic structures (right and left). A recent procedure known as TLIF (Transforaminal Lumbar Interbody Fusion) includes only one bone graft spacer being placed in the center of the interbody space, without the spinal nerves being retracted. Spondylolisthesis and degenerative disc degeneration, among other painful spinal disorders, are often treated using PLIF and TLIF surgeries.