Minimally Invasive Transforaminal Lumbar Interbody Fusion (MI-TLIF)

Background: Minimally invasive transforaminal lumbar interbody fusion (MI-TLIF) has been established as an excellent alternative to the traditional open approach for the treatment of degenerative conditions of the lumbar spine 1–3 . Description: The procedure is performed with the patient under general anesthesia and on a radiolucent table in order to allow for intraoperative fluoroscopy. The procedure is performed through small incisions made over the vertebral levels of interest, typically utilizing either a fixed or expandable type of tubular dilator, which is eventually seated against the facet joint complex 4 . A laminectomy and/or facetectomy is performed in order to expose the disc space, and the ipsilateral neural elements are visualized 5 . The end plates are prepared, and an interbody device is placed after the disc is removed. Pedicle screws and rods are then placed for posterior fixation. Alternatives: Nonoperative alternatives include physical therapy and corticosteroid injections. Other operative techniques include open TLIF or other types of lumbar fusion approaches, such as posterior lumbar interbody fusion (PLIF), anterior lumbar interbody fusion, lateral or extreme lateral interbody fusion, or oblique lumbar interbody fusion. Rationale: Open TLIF was developed in order to obtain a more lateral approach to the lumbar disc space than was previously possible with PLIF. The goal of this was to minimize the amount of thecal-sac and nerve-root retraction required during PLIF 4 . Additionally, as the number of patients who required revision after PLIF increased, the need arose for an approach to the lumbar spine that circumvented the posterior midline scarring from previous PLIF surgical sites 6 . MI-TLIF was introduced to reduce the approach-related paraspinal muscle damage of open TLIF 5 . Indications for MI-TLIF include most degenerative pathology of the lumbar spine, including disc herniation, low-grade spondylolisthesis, and spinal and foraminal stenosis 7 . However, MI-TLIF allows for less robust correction of deformity than other minimally invasive approaches; therefore, MI-TLIF may not be as effective in cases of substantial spinal deformity or high-grade spondylolisthesis 8 . Expected Outcomes: MI-TLIF results in significantly less blood loss, postoperative pain, and hospital length of stay compared with open TLIF 1–3 . Although some studies have suggested increased operative time for MI-TLIF 9,10 , meta-analyses have shown comparable operative times between the 2 techniques 1–3 . It is thought that the discrepancy in reported operative times is the result of a learning curve and that, once that is overcome, the difference in operative time between the 2 techniques becomes minimal 11,12 . One disadvantage of MI-TLIF that has remained constant in the literature is its increased intraoperative fluoroscopy time compared with open TLIF 3,13 . The complication rate has largely been found to be equivalent between open and MI-TLIF 1–3 or slightly lower with MI-TLIF 14 , especially in the hands of an experienced surgeon 15 . Finally, the fusion rate and improvement in patient outcome scores have also been found to be largely equivalent 1–3 . Important Tips: We suggest placing the ipsilateral pedicle screw after the interbody cage has been inserted. Fully visualize the Kambin triangle 16 prior to performing the facetectomy. Protect the exiting and traversing nerve roots by placing small cottonoids around them and retracting delicately. Bone removed during facetectomy can be utilized as autograft for the interbody cage. Avoid removing pedicle bone during decompression. If central stenosis is present, the neural decompression should be extended medial to the epidural fat so that the dura mater can be visualized all of the way to the contralateral pedicle. Perform an adequate end plate preparation prior to interbody insertion while being mindful to avoid injuring the end plate, to minimize the risk of future cage subsidence. Confirm correct placement of the interbody device on intraoperative fluoroscopy. If bone morphogenic protein is utilized, be careful not to pack too much posteriorly as this may cause nerve irritation. Acronyms and Abbreviations: TLIF = transforaminal lumbar interbody fusion MI-TLIF = minimally invasive TLIF PLIF = posterior lumbar interbody fusion ALIF = anterior lumbar interbody fusion LLIF = lateral lumbar interbody fusion XLIF = extreme lateral interbody fusion OLIF = oblique lumbar interbody fusion DLIF = direct lateral interbody fusion MRI = magnetic resonance imaging A/P = anteroposterior EMG = electromyographic BMP = bone morphogenic protein XR = x-ray (radiograph) OTC = over the counter DVT = deep vein thrombosis PE = pulmonary embolism MI = myocardial infarction MIS = minimally invasive surgery OR = operating room LOS = length of stay VAS = visual analog scale ODI = Oswestry Disability Index M-H = Mantel-Haenszel RR = risk ratio CI = confidence interval NSAIDs = nonsteroidal anti-inflammatory drugs