Introduction
Posterior lumbar interbody fusion techniques have been popular since the 1950. Specifically, posterior lumbar interbody fusion (PLIF) was a very popular technique; however, it required removal of both facets in order to achieve adequate graft positioning. To surpass the inherent limitations of the PLIF, Harms and Rollinger, in 1982, described the placement of the interbody bone graft via a transforaminal approach. In the transforaminal lumbar interbody fusion (TLIF) procedure, bone graft and an interbody spacer are placed via a posterolateral transforaminal route into a distracted disk space in conjunction with a supplemental pedicle screw construct. This TLIF approach allows less retraction of the thecal sac and neural structures; it spared the contralateral lamina and facet (vs. PLIF) providing a bigger surface for fusion. Additionally, advantages of the TLIF over PLIF are fewer complications, elimination of epidural scarring, and less intraoperative bleeding. Furthermore, given TLIF’s unilateral approach, preservation of the lumbar spine musculoligamentous complex is obtained. Recently some variations of the open TLIF have been described, such as the mini-open TLIF for a single-level approach. Despite the introduction of the minimally invasive TLIF (MIS TLIF), open TLIF is still routinely used in many centers owing to the high bony fusion achieved (>90%) and similar complications rate when compared with MIS TLIF.
Surgical Indications and Technique
Indications
The primary objective of any interbody fusion is to stabilize the spine. Table 8.1 shows the indications for lumbar interbody fusions. Table 8.2 presents the relative contraindications for the procedure.
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Technique
The patient is first placed under general anesthesia, intubated, and then positioned prone on a radiolucent surgical table ( Fig. 8.1 ). Intravenous antibiotics should be administered prior to performing the skin incision. The surgeon must avoid placing the patient in a flat-back or kyphotic position before performing the TLIF, because the patient may be fused into that nonphysiologic position. Positioning the patient in optional lordosis is accomplished by providing maximal hip extension during positioning. Pressure points are appropriately padded, and the surgical field is prepared and draped in a sterile fashion. Biplanar fluoroscopy may then be used to localize the indexed level accurately. A vertical incision (5–7 cm) is performed and the muscles and soft tissues are retracted laterally to expose the spinous processes, lamina, facet joints, and transverse process ( Fig. 8.2 ). A laminectomy, facetectomy, or both are performed, depending on the clinical presentation. Minimally, a unilateral laminotomy and partial facetectomy are performed on the more symptomatic side. The exiting nerve root is identified and carefully preserved.
Once the neural elements are adequately decompressed, pedicle screws are placed in a standard fashion. The disk space is then identified and a standard diskectomy is performed. Adequate removal of the cartilaginous endplate is necessary; however, preservation of the bony endplates is required to prevent graft subsidence. With the use of a combination of interspace wedges and serial distraction of the pedicle screws, an increase in disk height is accomplished and maintained ( Fig. 8.3 ).
