Transforaminal Lumbar Interbody Fusion

38 Transforaminal Lumbar Interbody Fusion

Mick J. Perez-Cruet, Moumita S.R. Choudhury, Esam A. Elkhatib, and Jorge Mendoza–Torres

Abstract

The minimally invasive transforaminal lumbar interbody fusion (MI-TLIF) approach and technique is one of the most versatile surgical treatment options for a variety of lumbar spinal disorders. The approach offers a muscle-sparing technique that can directly decompress the neural elements while providing optimal fusion and posterior instrumentation. The approach can also provide complete reduction of spondylolisthesis, which restores sagittal alignment, and foraminal and canal diameter. This chapter will illustrate this technique and some of the new innovative technology developed to facilitate the approach and improve patient outcomes.

Keywords: minimally invasive, TLIF, lumbar, spondylolisthesis, stenosis, chronic back pain

38.1 Introduction

Minimally invasive transforaminal lumbar interbody fusion (MI-TLIF) is a surgical technique used to stabilize the lumbar spine. The technique is extremely versatile and allows treatment of a variety of pathology including degenerative disc disease, spondylolisthesis with and without lumbar stenosis, and scoliosis. The posterior approach permits direct decompression of the neural elements and, collection of local autograft bone for fusion material, and promotes arthrodesis by placing bone graft material in the interspace between adjacent vertebrae ( Fig. 38.1). Comparative studies have shown the superiority of MI-TLIF to the similar open technique.¹^,²^,³^,⁴^,⁵^,⁶^,⁷ The technique represents an evolution in spine surgery by preserving normal anatomical structures and improving patient outcomes.⁸

38.2 Indications

MI-TLIF is used for conditions such as the following:

• Degenerative disc disease.

• Spondylolisthesis with or without stenosis.

• Instability due to trauma or tumors.

• Discogenic pain disorder.

• Stabilization after osteotomy.

• Pars interarticularis defect.

• Stabilization of degenerative discs or recurrent disc herniations.

• Scoliosis correction and stabilization.

These conditions are known to produce refractory chronic back pain disorders and can be considered indications for spinal fusion. Additionally, MI-TLIF is designed to replace the disc space with bone graft material to treat: isthmic spondylolisthesis (grades 1–4),⁹ junctional degeneration adjacent to a fusion mass, recurrent disc herniations with significant back pain, terminal end of long fusion constructs requiring interbody fusion, degenerative scoliosis, and postlaminectomy spondylolisthesis ( Fig. 38.2).¹⁰^,¹¹^,¹² These conditions can often result in foraminal stenosis causing compression of the exiting nerve root. Restoration of disc height, sagittal alignment, and foraminal circumference can be achieved using the MI-TLIF procedure.

Patients with osteoporosis, bleeding disorders, and active infection can be considered relative contraindications. However, since the MI-TLIF procedure is performed with minimal tissue destruction and blood loss, these patients can also be treated using this technique. Obese patients experienced clinically and statistically significant improvement in both pain and function after undergoing MI-TLIF. Since there is less tissue destruction, obese patients and those with medical comorbidities can be ambulated faster and they tend to recover quicker as well.¹²

38.3 Preoperative Planning

Thorough preoperative evaluation including physical examination is necessary to achieve optimal clinical outcome and to reduce the need for a revision operation and complications.

Radiographic workup typically includes plain X-rays with AP, lateral, flexion, and extension views. MRI of the lumbar spine is performed. In revision operations with hardware in place or patients with significant scoliosis, CT with myelogram is helpful. In those patients with no clear neurological compression, discography with postdiscography CT is useful in determining the possible source of the patient’s chronic back pain.

38.3.1 Decompression Alone versus Decompression with MI-TLIF

Determining the most appropriate surgical approach can help improve patient outcomes while providing focused treatment and unnecessary surgical time and intervention. We conducted a retrospective analysis of facet anatomy in a large series of patients and determined that facet could assist in identifying optimal surgical approach. Those patients found to have lumbar stenosis and facet lengths (i.e., length of superior and inferior facets) similar to nonpathological segments could be treated with decompression. In those patients with elongated facets and stenosis, decompression in combination with MI-TLIF provided excellent patient outcomes and reduced the incidence for subsequent surgical intervention. Conversely, the surface area of patients with elongated facet was also greater than nonpathological segments. Elongation of the facet complex occurs frequently in patients with spondylolisthesis, whereby the subluxation of one vertebra relative to the other over an extended period of time (i.e., years) results in facet elongation. The MI-TLIF procedure allows for solid stabilization of the segment and restoration of disc and foraminal height, and thus eliminates the process by stabilizing the spine segment, preventing recurrence of stenosis, and further subluxation of the vertebrae ( Fig. 38.3).

Fig. 38.1 Preoperative (a) sagittal and (b) axial T2-weighted MRI images showing L4–L5 grade 1 spondylolisthesis with associated stenosis. Postoperative (c) sagittal, (d) axial CT, and (e) postoperative incision following minimally invasive transforaminal lumbar interbody fusion approach showing restoration of normal sagittal alignment, adequate interbody graft, and central canal decompression while maintaining anatomical structures of the spine (i.e., spinous process and contralateral facet complex).

38.4 Surgical Technique

38.4.1 Patient Positioning

After the patient is intubated, a Foley catheter is placed and the patient is log-rolled onto a Jackson table (see Fig. 8.3). All pressure points are padded adequately. The Jackson table is helpful because it allows unencumbered fluoroscopic visualization of the spine and easy removal of the fluoroscopic unit, when not being used, away from the operative field toward the foot of the bed.

38.4.2 Spinal Approach

Incision

The patient is positioned prone with appropriate padding, prepped and draped in sterile surgical fashion. The midline is marked to help orient the surgeon. An 18-gauge spinal needle and lateral fluoroscopy is used to identify the level. An incision is then made 3 cm lateral to the midline directly over the disc space in which the MI-TLIF is to be performed in association with canal decompression. This distance from the midline allows access to the base of the spinous process for adequate minimally invasive laminectomy if decompression for stenosis is performed. If no decompression is required, we find that 3.5 cm from the midline is adequate and facilitates interbody implant positioning within the disc space. The fascia is cut parallel to the spinous processes and the One-Step-Dilator (Thompson MIS, Salem, NH) is used to approach the spine ( Fig. 38.4). The dilator is supported by a holder and is advanced under fluoroscopic guidance in a clockwise fashion. Once docked on the facet, counterclockwise rotation opens the flanges of the dilator, separating the muscle tissue, and a tubular retractor of the appropriate length is placed. The procedure is then performed under direct microscopic visualization through the tubular retractor. The approach is bloodless and does not require Kirschner’s wire (K-wire) or a series of muscle dilators, thus helping avoid inadvertent passage into the spinal canal and potential dural tear and/or nerve injury (see Fig. 38.4).