Advantages
The Posterior Lumbar Interbody Fusion (PLIF) procedure has a number of theoretical advantages over other forms of stabilization / fusion surgery:

• Intervertebral distraction (separation) enables the restoration of three dimensional spinal alignment / balance and indirect neurological decompression of the neural foraminae (nerve passageways) and lateral recesses.
• The interbody implants / graft subsequently maintain the disc space height and spinal alignment by supporting the load center.
• The intervertebral graft is placed under dynamic compression with potential load sharing depending upon the type of supplementary implants / technique used.
• The surface area for bone graft healing is maximized (again, depending upon the type of supplementary implants / technique used).

Several studies have shown the importance of anterior column structural support following deformity correction, especially of low and high grade spondylolisthesis (3,6,10,11,12). Posterolateral fusion alone in this setting will frequently fail due to the biomechanical stresses placed upon the instrumentation as well as placing the graft under tension rather than compression. In a series of 76 patients undergoing decompression and fusion for spondylolisthesis, Suk (12) found hardware failure in 2 and non-union in 3 out of 40 (7.5%) patients undergoing posterolateral fusion but no nonunion in the 36 patients undergoing PLIF. In the posterolateral group, the mean postoperative correction of the slip was 46.5% but this had reduced to 28.3% at final follow-up. In the PLIF group, mean postoperative correction was 51.6% and was 41.6% at final follow-up.

Indications
Principal indication:

The principle indication for Posterior Lumbar Interbody Fusion (PLIF) surgery is in the stabilization and fusion of the spine following correction of adult spinal deformity. Degenerative deformity is a common and often missed cause of neurological compression. Foraminal stenosis in particular, associated with disc space narrowing, spondylolisthesis (vertebra slips forward), retrolisthesis (vertebra slips backward) or scoliosis may be difficult to relieve without correction of the associated deformity (Figure 1).

Figure 1. Foraminal stenosis and L5 nerve root compression
associated with Lumbosacral (lumbar and sacrum) spondylolisthesis.

Secondary indications include:

• Surgery for lumbar disc herniation, especially recurrent, lateral or massive disc herniations
• Failed previous fusions by other techniques
• Discogenic low back pain