Once the patient is positioned and prepared in a sterile fashion, the lumbar level or levels of interest are marked with the use of fluoroscopic visualization. The surgeon can choose to perform the TLIF on the side with the greatest clinical and/or radiographic pathologic abnormality. A standard midline incision is created through the skin and subcutaneous tissues. The dissection is continued in a standard subperiosteal manner, which might include the transverse process of the involved levels (Figure 2, A). Once dissection is achieved, pedicle screws are placed at the indicated level or levels (Figure 2, B). Next, a window is created to access the disk space (Figure 3). The inferior articular facet of the cephalad vertebra and the superior articular facet of the caudal vertebra are resected. To achieve resection, a straight osteotome is used to create a partial laminotomy in the inferior lamina of the cephalad vertebra (Figure 4, A); the pars interarticularis is then transected and the inferior facet of the vertebra above is removed (Figure 4, B). Kerrison and Leksell rongeurs are used to resect the superior articular facet of the caudal vertebra (Figure 4, C). This bone is saved to be used as local autologous bone graft.

Once the working window is created, the exiting nerve root is decompressed, and completion of the facetectomy allows for the traversing nerve root to be visualized and freed up. Bipolar cautery is applied to bleeding epidural vessels, and a nerve root retractor is placed medially to protect the dural sac. The advantage of the transforaminal approach is that minimal retraction of the dural sac
is needed. Exposure of the disk space is achieved with a Penfield dissector. A large box-cut annulotomy is created in the disk space to begin a thorough and complete diskectomy.

The diskectomy is initiated with straight pituitary rongeurs and curets (Figure 5, A) and is continued with angled pituitaries and curets (Figure 5, B) to access the contralateral disk space. Disk and cartilage material is carefully removed from the superior and inferior end plates with straight and angled curets. Sequential dilators and shavers can be used to open up the disk space and facilitate a complete diskectomy (Figure 6).

Once the end plates are prepared, a lamina spreader can be used to help distract at the spinous processes. Alternatively, additional distraction force can be applied to the pedicle screws (Figure 7). Once serial dilation has achieved the desired fit, a trial implant is inserted and tamped anteriorly and medially. The fit of the trial implant is confirmed with tactile feedback and radiographically. The trial is then removed, and the implant is tamped into the anterocentral aspect of the disk space (Figure 8). This positioning optimizes the load-sharing capacity of the implant and helps restore lumbar lordosis.

If pedicle screws were not inserted at the start of the procedure, they are inserted at this point. Rods are then placed, and compression is applied to compress the interbody graft and to improve the lumbar lordosis. Final tightening of the implants is performed, and radiographic confirmation of appropriate implant and graft placement is assessed (Figure 9). The surrounding bone is decorticated with a high-speed burr to form a fusion bed. Depending on the clinical scenario, the surgeon might choose to perform an intertransverse process fusion. The foramen and canal are probed to verify that no free bone is present. The wound is irrigated, and bone graft is placed meticulously about the fusion bed. Finally, wound drains are placed and the wound is closed.