Transforaminal Lumbar Interbody Fusion (TLIF): Advantages
Part Two of Five
The first one, which is the most obvious, is the unilateral nature. This results in less destruction of the posterior elements and less gross destabilization of the spine, which will maximize fusion stability. Although Posterior Lumbar Interbody Fusion (PLIF) techniques in the past have offered the ability to perform an anterior and isolated posterior procedure, the unilateral technique allows for much less perineural retraction, scarring, and preserves more bony surface for posterior spinal fusion. This can be stated because the contralateral facet joint is maintained intact with respect to its bony anatomy.
Transforaminal Lumbar Interbody Fusion (TLIF) allows, as part of the dissection, a far lateral access to the neural foramina to decompress both the traversing and exiting upper nerve root without neural manipulation. This avoids nerve retraction injuries that are seen often with the PLIF and bilateral posterior interbody fusion techniques. A far lateral access to the disc space can be performed within the safe zone between the upper exiting nerve root and the traversing lower nerve roots.
Due to the simplified procedure and the unilateral technique, the operative time, potential blood loss, and the risk to the neural structures is reduced. One of the greatest advantages of TLIF is the working zone within the disc space. Unlike the bilateral standard posterior lateral interbody fusion techniques, the working zone for the unilateral technique begins at the lateral aspect of the dural sac and moves further lateral into the foramina. Exposure of the nerve elements is the key to this technique and gaining exposure from the pedicle above to the pedicle below. This working zone protects the neural structures from over distraction and allows the surgeon to visualize the upper existing nerve root and the dorsal root ganglion, as well as the volar traversing nerve root. With minimal retraction of the dura and with working within the foramina, the surgeon is able to gain complete access to the disc space to perform the necessary discectomy, curettage, and distraction, as well as placement of instrumentation and eventual fusion construct.
Using an impacted arthrotic device in a bilateral posterior lumbar interfusion technique requires manual retraction of the majority of the dura on each side to gain more central lateral exposure; and then subsequently performing the same maneuver on the contralateral side for the placement of the second device. This certainly creates further scarring and potential for neural injury. The unique features of the translumbar interbody fusion technique revolve around the ability to convert distraction of the disc space and kyphosis into a compression lordosis construct. The surgeon is able to restore interbody height to a distraction and then compress posteriorly to restore lordosis across the fulcrum of the anterior interbody graft. This compresses the anterior graft further stabilizing it and adding to its fusion potential. In doing so, the surgeon can achieve anywhere between 5-degrees to 10-degrees of lordosis per level and can correct modes low-grade spondylolisthesis deformities.
The indications for translumbar interbody fusion include:
1. Degenerative disc disease with a specific discogenic pain pattern.
2. Low grade 1 or grade 2 spondylolisthesis.
3. Incontinence of the anterior column in association with posterior pathology.
4. Fixation across the lumbosacral junction especially with long segment fusion or when a 360-degree fusion is desired.
Some of the more ideal indications include cases in which there has been a previous decompression for a herniated disc or previous laminectomy where the patient presents with unilateral radiculopathy requiring revision decompression in association with micro-instability, spondylolisthesis, or degenerative disc disease. In this case, a wide decompression of the ascending neural compression will result in a rather large foraminotomy, which in doing so will virtually provide exposure needed for translumbar interbody fusion. It is a misindication at best to utilize the advantages of TLIF because a bilateral manipulation of the neural elements, especially in a revision situation, is not necessary. There are also minimally invasive strategies that can be performed percutaneously as neural developments continue to improve, which should allow for transforaminal percutaneous pedicle screw placement and interbody fusion techniques.