Transforaminal Lumbar Interbody Fusion (TLIF) Technique
Part One of Five
The goals of posterior spinal surgery in the lumbar spine typically involve decompression of the neural elements. However, in many cases such techniques are associated with iatrogenic instability, worsening of pre-existing deformity, instability, or potential for further neurologic compromise in the future.
Situations involving revision surgery or failed previous fusions have also led to the identity of certain factors, which may predispose to persistent pain or morbidity after lumbar spine reconstruction spinal surgery. It has been well-recognized since the early days of posterolateral spine fusion that a successful neurologic decompression was not always associated with successful radiographic and clinical union of the arthrodesis. In some instances, the patient's clinical picture remained excellent and further intervention was not necessary. However, pseudoarthrosis and the difficulties and clinical perils that arise from failure to fuse the posterolateral intertraverse process space have led many to devise enhanced techniques to maximize successful fusion and maximize clinical outcomes.
In addition to the difficulties with obtaining a posterolateral intertransverse process fusion, there quite often exists definitive anatomical disease in the anterior column ventral to the neurologic space within the endplates or the disc itself, which not only contributes to the preoperative symptomatology, but which demands attention in order to obtain a successful clinical outcome. In such instances, the surgeon must consider incorporating in the fusion construct both the anterior and middle columns of the spine through intervention within the disc space, as well as a solid posterolateral arthrodesis technique. It has been clear in past literature that direct decompression of anterior pathology such as infections, tumors, and fractures is best approached via a ventral or anterior dissection.
However, there are certainly instances, especially in the degenerative spine, where the surgeon is required to at least in part perform a posterior lumbar surgical exposure. In these instances, an efficient and advantageous means to gain access to the anterior column and disc space is through the single posterior lumbar incision. It is in this situation that the Posterior Lumbar Interbody Fusion (PLIF) technique is best applied. Although the PLIF technique from a bilateral approach is well-known in the clinical and academic literature, the development of the unilateral Transforaminal Lumbar Interbody Fusion (TLIF) technique has allowed the surgeon to approach the interbody disc space posteriorly in a more efficient and isolated fashion, thereby diminishing the overall morbidity to the neural structures.
TLIF is a unilateral technique that allows the surgeon to access the interbody disc space to augment a posterior spinal lateral intertransverse process fusion. The TLIF technique is advantageous over the posterior spinal fusion technique alone because the surgeon is able to restore intervertebral body height, reduce spondylolisthesis and degenerative instability, and enhance lordosis by maintaining anterior column height with posterior spinal fixation. This technique also allows the surgeon to enhance the potential for fusion by obtaining a circumferential fusion surface area and address anterior column pathology directly, which cannot be adjusted via a posterior intertransverse process fusion technique alone.
When comparing the TLIF to the Anterior Lumbar Interbody Fusion (ALIF) technique, one sees that a posterior spinal decompression allows for direct nerve decompression in addition to the interbody technique. The posterior decompression exposure also allows for advantages related to pedicle fixation to maximize and enhance stability, assist in deformity correction, and facilitate rigid fixation.
There are certainly risks associated with the posterior technique, which is primarily neural in origin. These are certainly more commonly dealt with and more routine in nature than the potentially catastrophic vascular risks that are inherent with the ALIF technique. Although these stated advantages are considerable, there are limitations to the posterior interbody technique. This is especially seen in significant kyphotic cases where TLIF is less able to achieve maximal lordosis than a direct anterior exposure and fusion.
So in summary, the most common rationale for TLIF is to obtain anterior column support through a one-incision posterior approach while simultaneously performing any decompressive surgery necessary and posterior spinal fusion with instrumentation. There is also the added biological advantage of an interbody fusion technique with compression across a structural fusion cage or apparatus, which will add to the success of a lumbar arthrodesis procedure. There are several advantages distinct and to the TLIF approach.