Introduction
Degenerative disease of the lumbar spine has increased with the aging population and the number of elective lumbar spinal surgeries has also increased. Concurrently, the number of revision lumbar spinal surgeries has also increased as patients experience recurrence of symptoms or develop adjacent segment disease after their initial surgery. The transforaminal lumbar interbody fusion (TLIF) was developed as a technique to obtain an interbody fusion through a posterolateral approach with less manipulation of the thecal sac and nerve roots. The transforaminal approach achieves this by providing a trajectory into the disc space through Kambin’s triangle in the axilla of the exiting nerve root.
A failed TLIF may require salvage surgery when the patient develops new or recurrent symptoms. A thorough physical examination and history are helpful in assessing potential causes of recurrent or persistent pain after a previous lumbar surgery. Given that revision surgery has been shown to improve health-related quality-of-life outcomes, it is essential to identify those patients whose TLIFs have not fused and offer them a revision surgery. For example, mechanical back pain shortly after a previous lumbar fusion surgery may be indicative of a migrated cage. Moreover, nonmechanical back pain with constitutional symptoms such as fever, weight loss, or chills shortly after a previous fusion surgery may indicate a surgical site infection that could involve the interbody cage. Also, recurrent pain or new progressive weakness several months to years after an initial lumbar fusion surgery may indicate pseudarthrosis or adjacent segment stenosis. In this chapter, we will discuss methods to salvage a failed TLIF and discuss how TLIF can be used to treat progressive spinal disease after a previous lumbar surgery.
Pseudarthrosis, Subsidence, and Cage Migration
An interbody cage inserted through a transforaminal corridor via Kambin’s triangle is typically smaller than cages placed via an anterior or lateral approach. Thus TLIF cages may result in pseudarthrosis or subsidence of the cage into the adjacent endplates of the vertebrae. Common causes for TLIF failure are undersized cages, subsidence of a cage into the end-plate, posterior cage migration into a nerve root or the thecal sac, and pseudarthrosis. Various approaches can be used to revise and salvage the failed TLIF level, including an anterior approach, a posterior-only approach, and a lateral approach. All approaches aim to remove or reposition the previously placed cage, increase disc and foraminal height to decompress the exiting nerve roots, and increase the likelihood of fusion of the revised segment.
Revision of Transforaminal Lumbar Interbody Fusion Using an Anterior Approach
An anterior approach provides a clearer and wider exposure for direct access for removal of the previously placed TLIF cage and insertion of a larger anterior interbody cage. An anterior cage also allows for more contact between the cage and the anterior apophyseal ring to mitigate the risk of subsidence after the revision. Revision of a TLIF using an anterior lumbar interbody fusion (ALIF) cage has been shown to have biomechanically favorable results. The fusion rates associated with a direct anterior-only approach versus a combined direct anterior approach coupled with a posterior exploration and pseudarthrosis repair are very similar, 81% versus 88% respectively. As seen in Case 1 , a combined anterior and posterior approach can be used to revise a TLIF with pseudarthrosis. Fig. 13.1 shows no solid fusion of the interbody cage, resulting in subsequent collapse of the expandable cage and pedicle screw fracture. With an ALIF, the residual disc is removed followed by removal of the nonhealed TLIF cage. The TLIF cage can be removed in one piece or cut out using osteotomies and a Leksell rongeur in a piece-meal manner.
A 37-year-old male developed recurrent low back pain and right leg radicular pain, and was found to have collapse of his expandable TLIF cage and fracture of the right S1 screw ( Fig. 13.1 ). He underwent an L5–S1 anterior approach for removal of the collapsed cage and implantation of a large anterior interbody cage, and posterior removal and replacement of the rods and screws.
The ALIF approach is associated with a rare chance of potential complications such as retrograde ejaculation, impotence, and retroperitoneal fibrosis. Thus preoperative discussion of these risks with young, male patients is recommended.
Revision of Transforaminal Lumbar Interbody Fusion Using a Posterior-Only Approach
There are two options for revising a TLIF using a posterior-only approach to allow for implantation of a new interbody cage for fusion. The first option is an ipsilateral transforaminal approach for removal of the previous cage and placement of a new cage, as illustrated in Case 2 . The advantage of this option is that it involves replacing the cage, which did not fuse. As demonstrated in Fig. 13.2 , an ipsilateral transforaminal approach can be to used to revise a migrated TLIF cage. Additionally, it allows the contralateral side to be kept intact, should further salvage/revision surgery be required. However, the operative corridor typically has a significant amount for scar and fibrous tissue around the nerve root and thecal sac that need to be dissected to regain access to the disc space. The dissection of this scar tissue is fraught with the risk of a dural tear. Thus an ipsilateral approach is not advisable in patients who have a significant amount of scar tissue over the ipsilateral transforaminal corridor without an easily dissectible plane or who had a previous dural tear during the initial surgery.
A 61-year-old male with previous L2–S1 posterior instrumentation for fusion and L2–L3 TLIF was found to have posterior migration of the TLIF cage ( Fig. 13.2 ). The patient underwent an ipsilateral removal of the migrated L2–L3 TLIF cage, insertion of a new larger L2–L3 TLIF cage, and placement of new L1–L2 TLIF cage, with extension of the fusion down to the pelvis.
The second option is a contralateral TLIF approach for placement of a new cage, as illustrated in Case 3 . This option has the distinct advantage of using the nascent foramen for access to the disc space. Thus there is less dissection of scar tissue and a lower risk of a dural tear. Once the contralateral annulotomy is performed, a new cage can be inserted adjacent to the previously placed cage, as demonstrated in Fig. 13.3 . Additionally, the insertion of the new cage can be used to push the previously placed cage into an ideal position.
A 44-year-old female presented with morbid obesity, prior left L5–S1 TLIF with a polyetheretherketone (PEEK) cage, and subsequent pseudarthrosis ( Fig. 13.3 ). The patient underwent right L5–S1 TLIF with titanium cage and revision of the pedicle screws.
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