Endoscopic Transforaminal Lumbar Interbody Fusion and Instrumentation

20 Endoscopic Transforaminal Lumbar Interbody Fusion and Instrumentation

Faheem A. Sandhu

20.1 Introduction

In the early 1900s, dorsal lumbar fusion techniques were often unsuccessful. This led Muller to attempt to treat patients who had Potts disease through an anterior approach.1 In the 1930s, Burns performed a successful transabdominal lumbar interbody fusion for traumatic spondylolisthesis.¹ In the 1940s, interbody fusion techniques were further modified to include placement of an autograft, in the form of the removed spinous process and lamina, into the intervertebral space.^2,3 In 1953, Cloward reintroduced the concept of the posterior approach for lumbar interbody fusion and advocated that this technique replace stand-alone lumbar diskectomy and laminectomies.⁴ Through Cloward’s posterior lumbar interbody fusion (PLIF), 360° of stabilization was achieved via a single dorsal incision, eliminating the need for additional anterior surgery.⁵ However, the risks involved with the approach were not insignificant and included neural injury from significant retraction of the thecal sac and nerve root, as well as CSF leak.

In an attempt to reduce the complications associated with PLIF, Harms and Rolinger introduced an alternative method to achieve circumferential lumbar fusion in 1982.⁶ By means of a unilateral facetectomy, a transforaminal window was created for placement of a titanium mesh and bone graft. In comparison to the PLIF, the transforaminal approach for lumbar interbody fusion (TLIF) decreases retraction of the neural elements and is performed from a unilateral approach.⁶ TLIF also allows for more anterior placement of a larger interbody graft, thereby achieving greater foraminal decompression and restoration of lumbar lordosis. Furthermore, the TLIF avoids disruption of the contralateral facet and pars and is also associated with significantly less blood loss.^7,8,9

The most recent advancement in lumbar interbody fusions is the development of minimally invasive (MI)/endoscopic techniques.^10,11,12 The open TLIF approach causes disruption of the musculoligamentous complex and requires significant lateral retraction of the musculature for adequate exposure of the surgical anatomy. This has been negatively correlated with long-term lumbar fusion outcomes.^13,14 The development of tubular retractor systems has allowed the achievement of lumbar arthrodesis while minimizing soft tissue damage.^15,16,17 This chapter reviews the appropriate candidates for the procedure, the surgical technique, and details on how to avoid the complications and pitfalls of the MI/endoscopic TLIF.

20.2 Choice of Patient

Indications

The indications for the procedure include:

• Grade I/II spondylolisthesis with dynamic instability

• Pseudoarthrosis

• Postlaminectomy lumbar kyphosis

• Degenerative disk disease and mechanical back pain with reproducible symptoms on provocative testing

• Recurrent disk herniation with mechanical back pain

• Interspace collapse with radiculopathy after diskectomy

• Three or more recurrent disk herniations with radiculopathy

• Instability secondary to trauma

• Lumbar deformity with coronal/sagittal imbalance

Contraindications

Contraindications to the procedure are:

• Multilevel degenerative disk disease without deformity

• Single-level disk disease without mechanical back pain or instability

• Severe osteoporosis

20.3 Technique

Surgical Equipment

• The open Jackson table is preferred, because it promotes lumbar lordosis and decreases intra-abdominal pressure and epidural vein congestion.

• C-arm fluoroscopy

• Expandable tubular retractor

• Endoscope, loupe with headlight, or microscope

• High-speed drill

• Standard laminectomy/fusion surgical set

• Distractors (7–14 mm), rotating cutters, end plate scrapers

• Interbody graft material (polyether ether ketone [PEEK] cage or titanium cage)

• Bone graft material

• K-wire

• Cannulated pedicle screws

Operating Room Setup

• Operating table is placed in the center of the room.

• Anesthesia is positioned at the head of the table.

• C-arm fluoroscopy base is placed on the side opposite the surgical approach.

• Equipment tables should be situated behind the primary surgeon, with the Mayo stand over the patient’s feet.

Anesthesia/EMG

• Anesthesia should be asked to avoid paralytics, nitrous oxide, and muscle relaxants, to prevent any interference with EMG recordings.

• Intubation

• Placement of the Foley catheter, EMG leads on the lower extremities, and sequential compression devices should be completed prior to placing the patient in the prone position.

• Preoperative antibiotic should be administered. (We prefer cefazolin or vancomycin if the patient has a penicillin allergy.)

Positioning and Localization

• The patient is placed in the prone position on an open Jackson table.

• The C-arm is used to localize and mark the level(s) of pathology (Fig. 20.1) (Video 20.1).

Exposure

• A 2.5-cm longitudinal incision is made 4 cm from the midline on the symptomatic side.

• The incision should be carried down to the dorsal lumbar fascia (Fig. 20.2).

• A Steinmann pin is inserted at 35° to 45° to rest on the facet complex, and this is confirmed with fluoroscopy (Fig. 20.3).

• Sequential soft tissue dilators and tubular retractors are used to split muscle (Fig. 20.4).

• The tubular retractor is secured to the table with a flexible arm clamp and the correct level is confirmed with C-arm fluoroscopy (Fig. 20.5).

• Soft tissue overlying the lamina and facet complex is then removed using monopolar cautery (Fig. 20.6).

Laminectomy/Facetectomy

• The working channel is then angled medially for performance of the laminectomy and facetectomy.

• Using a straight curet, the inferior edge of the lamina is defined.

• Using angled curets, a plane is developed between the undersurface of the lamina and the ligamentum flavum.

• The lamina is thinned with a high-speed drill (Fig. 20.7) and then is removed using angled Kerrison rongeurs. This decompression should extend from pedicle to pedicle at the levels above and below the interspace.

• Alternatively, an osteotome can be used to remove the facet by making cuts along the medial aspect of the facet and one perpendicular to this at the base of the pars (Fig. 20.8). The remainder of the lamina is then removed with Kerrison rongeurs.

• A total facetectomy is also performed in preparation for placement of the interbody cage.

• The bone removed in the laminectomy and facetectomy is saved for use as part of the interbody and lateral fusion mass.

Fig. 20.1 (a,b) Patient in the prone position, level of pathology localized with C-arm fluoroscopy, and 2.5- cm incision marked on the patient’s symptomatic left side.

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