Awake spinal fusion - Endoscopic facet sparing transforaminal lumbar interbody fusion under caudal epidural: A game changer

Rahul Ahluwalia

doi:10.4103/joss.joss_43_22

ORIGINAL ARTICLE

Year : 2022 | Volume : 9 | Issue : 4 | Page : 212-217

Awake spinal fusion - Endoscopic facet sparing transforaminal lumbar interbody fusion under caudal epidural: A game changer

Rahul Ahluwalia
Department of Neurosurgery, Suyash Hospital, Raipur, Chhattisgarh, India

Date of Submission	20-Sep-2022
Date of Acceptance	01-Nov-2022
Date of Web Publication	30-Dec-2022

Correspondence Address:
Rahul Ahluwalia
29, South Avenue, Choubey Colony, Raipur - 492 001, Chhattisgarh
India

Source of Support: None, Conflict of Interest: None

DOI: 10.4103/joss.joss_43_22

Abstract

Background: Trans-Kambin fusion offers the advantage of providing reduced morbidity and awake surgery allowing for patient's own neuromonitoring during the procedure, along with reduced hospital stay, early mobilization, reduced blood loss, and reduced operative time, while maintaining the standard of fusion that can be achieved with open/MISS transforaminal lumbar interbody fusion.
Objective: Spinal fusions done under GA have restrictions when it comes to patients with OSA/COPD/Cardiac dysfunction, etc. Awake Endoscopic Spinal fusion surgeries can provide a novel solution to such patients.
Material and Methods: EKLIF was performed in total of 19 patients with 17 single-level and 02 patients with multilevel lumbar discopathy and/or degenerative spondylolisthesis resulting in axial back pain and claudication, pseudoradicular, or radicular symptoms. Endoscopic discectomy and interbody cage insertion were performed through a 1 cm lateral incision used for transforaminal access, followed by percutaneous pedicle screw-rod fixation. Clinical outcome was assessed by early postoperative pain scores (visual analog score [VAS]). Fusion rates were assessed by X-rays at 6 months. Clinical outcome, time in the operating room, intraoperative blood loss, VAS at preoperative, immediate postoperative, and after 6 months were determined.
Results: Excellent and good clinical results were obtained in 16 (84%) out of 19 patients at 6 months. The mean time spent in the operating room 71 min and no patient required a blood transfusion. The mean hospital stay was 2.8 days, with one patient having a prolonged stay of 8 days due to an intraoperative dural tear that was managed conservatively. There was no morbidity related to instrumentation. Postoperative stay was reduced with all patients mobilized on the next day of surgery. Fusion was visible in all patients on follow-up imaging at 6 months. The mean VAS of the study group before surgery was 6.63 with a significant change to 2.94 in the immediate postoperative period. At 6-month follow-up, the mean VAS was 1.3.
Conclusions: EKLIF allows for safe and efficient minimally invasive treatment of single and multilevel degenerative lumbar instability with good clinical results. Further prospective studies investigating long-term functional results are required to assess the definitive merits of trans-Kambin fusion of the lumbar spine.

Keywords: Awake fusion, awake spine surgery, EKLIF, endolif, PELD, spine fusion, transforaminal lumbar interbody fusion

How to cite this article:
Ahluwalia R. Awake spinal fusion - Endoscopic facet sparing transforaminal lumbar interbody fusion under caudal epidural: A game changer. J Spinal Surg 2022;9:212-7

How to cite this URL:
Ahluwalia R. Awake spinal fusion - Endoscopic facet sparing transforaminal lumbar interbody fusion under caudal epidural: A game changer. J Spinal Surg [serial online] 2022 [cited 2023 Apr 2];9:212-7. Available from: http://www.jossworld.org/text.asp?2022/9/4/212/366321

Introduction

Lumbar interbody fusion has long been used in the treatment of degenerative disc disease. It was first described by Bagby.^[1] Conventional posterior lumbar interbody fusion (PLIF) was first described by Briggs and Milligan in 1944,^[2],[3] advancement further in the form of transforaminal lumbar interbody fusion (TLIF) was done by Harms and Rollinger in 1982 where by a lateral approach reduced the thecal sac and root retraction.^[4] Apart from these posterior approaches, lateral lumbar interbody fusion techniques such as the transposase approach were pioneered by Mobbs et al. and further refined by Michael Mayer to incorporate L5-S1 fusions also, naming it oblique lumbar interbody fusion.^[5]

Unfortunately, the need for paraspinal muscle dissection and retraction remains a drawback that can lead to muscle denervation and atrophy and consequently, persistent low back pain. In addition, the postoperative pain and disability associated with an open approach led to the development of the minimally invasive TLIF. This was first introduced by Foley and Lefkowitz in 2002 with the aim of reducing tissue damage associated with the exposure and approach while maintaining the ability to achieve neural decompression and adequate interbody fusion.^[6]

Endoscopic lumbar interbody fusion is in its infancy with various reports published all across the globe such as Khoo et al. and Wang et al. who used a modified 20-mm trocar to place interbody grafts.^[7],[8] Jacquot and Gastambide published their report suggesting a high rate of complications in their technique of transforaminal percutaneous lumbar interbody fusions.^[9] Heo et al. reported a posterior biportal endoscopic technique for achieving lumbar interbody fusion.^[10] Morgenstern and Morgenstern performed percutaneous transforaminal interbody fusion for degenerative disc disease using general anesthesia with a 12-mm bevel-ended cannula whereby they first performed a posterior pedicle screw fixation, followed by interbody cage placement under general anesthesia.^[11] Sharma et al. published a case report describing the technique under conscious sedation.^[12]

It is a known fact that MiS-TLIF achieves fusions rates similar to open TLIF and with the advantages of reduced hospital stay and reduced blood loss. Yet it carries invasiveness to the extent of partial laminotomy, facetectomy, and ligamentum flavum excision.^[13] These steps are avoided in endoscopic transforaminal lumbar interbody fusion.

We present an innovative trans-Kambin fusion technique in an awake patient using the endoscopy-based transforaminal posterolateral approach with a minimal incision of 1 cm for insertion of an interbody cage. Therefore, the need for bone removal and open dissection required by classic TLIF and MIS TLIF techniques is eliminated. The study was designed as a single-site, single-surgeon, nonrandomized study to assess the feasibility of the trans-Kambin fusion technique with a posterolateral approach in an awake patient. The posterolateral approach was performed using standard telescopic instrumentation. Interbody fusion implants placed varied in size from 7 mm × 26 mm to 12 mm × 30 mm depending on the patient's profile.

The aim of the study was to assess the feasibility of performing trans-Kambin fusion in patients with degenerative disc disease +/− spondylolisthesis, patients with spondylodiscitis, and patients with the postoperative failed back syndrome.

Materials and Methods

Patients

Between August 2021 and February 2022, a total of 19 patients (13 females and 6 males) underwent the procedure. All patients were primarily seen by the principal author at our center. All patients were thoroughly counseled regarding the available modalities of treatment and possible complications in each. Written informed consent was taken from all patients.

Inclusion criteria were all patients presenting with degenerative disc disease with features of instability (clinically and/or radiologically on X-rays) +/− radicular pain, all patients with Grade 1 or 2 spondylolisthesis, and spondylodiscitis with persistent pain.

Patients with significant flavum hypertrophy causing canal stenosis were excluded from the study.

Operative technique

The patient is taken to the operative suite and standard premedication is done by our anesthetist-injection midazolam 2 mg i.v. along with injection fentanyl 100 μg or injection pentazocine 30 mg i.v. A Foley and Lefkowitz's catheter is placed under all aseptic precautions and the patient is positioned prone on the operative table over radiolucent bolsters positioned under the chest and pelvis. All necessary parameter recordings are connected to the monitoring system (electrocardiography, oxygen saturation, and blood pressure). Under fluoroscopic guidance, a caudal epidural catheter is positioned with the tip at L5-S1 and confirmed with dye and fluoroscopy. 10 ml of 0.25% bupivacaine is injected through the epidural catheter and supplemented as needed during surgery. 40-mg propofol is used as a supplementary sedation at the time of advancement of the working sheath within the disc and while placing the cage.

First stage: Endoscopic discectomy

The patient is prepped and draped under all aseptic techniques using specifically designed spinal drape sheet. 18 G needle is inserted into the disc as described by Yeung and Tso.^[14] Once the needle is positioned inside the disc, guidewire and serial dilators are used to insert the final working dilator of size 7 mm over which a beveled working sheath is inserted always with smooth surface facing toward the exiting root [Figure 1]. A standard discectomy is performed with help of graspers and radiofrequency cautery. Annulectomy is done as per need in the case. End plate preparation is achieved under vision using curettes and graspers. Visualized bleeding endplates are then confirmed before cage placement [Figure 2].

Figure 1: Image demonstrating trans-Kambin placement of needle, working dilator, and cannula

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Figure 2: Bleeding end plates visualized through endoscope

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Second stage: Interbody graft placement

An adequately sized rigid titanium interbody graft filled with hydroxyapatite blocks is positioned within the disc space. Now, two separate types of rigid interbody cages can be placed. The first [Figure 3] is a standard PLIF cage which can be filled with allograft and inserted within the disc space using a specifically designed dilator/sheath system of size 12 mm; the second [Figure 4] is a rigid titanium cage that is cannulated and once filled with allograft can be mobilized over a guidewire.

Figure 3: Standard PLIF cage introduced using a specifically designed dilator-sheath system of size 14 mm

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Figure 4: Cannulated titanium cage with allograft placed guided over a guidewire

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Third stage: Posterior pedicle screw fixation

The final step is posterior instrumentation. Adequately sized pedicle screws were placed under fluoroscopy. At this point, the sedation of the patient was deepened and the liberal local anesthetic agent was infiltrated into the periosteum. Many patients, where the author felt that significant instability was not present, were managed using ipsilateral pedicle screw placement only [Figure 5]. Post operative images were shown in [Figure 6] and [Figure 7] and [Video 1 [Additional file 1]].

Figure 5: L4-5 EKLIF with ipsilateral fixation

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Figure 6: Post-operative axial and sagittal scans showing Interbody graft at L4-5

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Figure 7: Post-operative axial and sagittal scans showing Interbody graft at L-L5-S1 of same patient

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Results

The study population included 13 women and 6 men with a mean age of 54 years (standard deviation: 14 years). Two patients underwent a double-level fusion while the remaining 17 had a single-level fusion. None of the patients required any blood transfusion as the mean blood loss was 25 ml. Pathological distribution of disease in the population was 53% spondylolisthesis (11 with Grade 1 and 2 with Grade 2 spondylolisthesis), 32% degenerative disc disease, 10% spondylodiscitis, and 5% had postoperative status [Graph 1].

Pathology

Pie-Chart showing Pathology based distribution of patients in study group.

Operative time and hospital stay

The mean operative duration was 71 min with a standard deviation of 26 min. The mean hospital stay was 2.89 days with a standard deviation of 1.59 days [Graph 2] and [Graph 3].

Visual analog score at preoperative, postoperative 24 h, and After 6 months

Outcome assessment was done based on visual analog score (VAS) pain score before surgery, 24 h after surgery, and after 6 months of surgery. The change of VAS score was statistically significant with a P = 0.0061 (using two sample t-tests) [Graph 4].

Discussion

This technique of Endoscopic TransKambin Lumbar Interbody Fusion (EKLIF) allows the patient to experience a truly minimally invasive form of spine fusion where an interbody graft (cage) is positioned through the natural corridor of Kambin's triangle. The smallest skin incision for a classic MIS TLIF approach reported in the literature is of 30 mm in length, requiring a mean postoperative time until hospital discharge of 9.3 (2.6 days).^[15] In contrast, the EKLIF approach reported here required a skin incision of 10 mm length, and a mean postoperative time until hospital discharge of 2.8 days.

The novelty of this technique is that it ensures the natural stability mechanism of the spine as no bone/ligament removal is done in contrast to MIS TLIF where by a laminotomy along with resection of articular processes and ligamentum flavum is always required. Apart from this, another added advantage is the ability to place the graft with zero root retraction ensuring no damage to the traversing root at the concerned level. An addition of foraminoplasty in required cases (hypertrophic facet/collapsed disc space/soft-tissue knot around SAP) further safeguards the nerve root.

Hence, the new EKLIF approach seems to be a promising, truly minimally invasive surgical technique for patients with DDD or spondylolisthesis up to grade 2. The EKLIF technique has an added advantage for revision surgery cases, as it allows placing a cage in a previously operated disk level by avoiding scar tissue, reducing the risk of dural tear or nerve damage.

The major drawback of this technique is its inability to deal with hypertrophic ligamentum flavum causing canal stenosis. Such patients should not be offered this technique of fusion unless one is willing to do a posterior endoscopic decompression using PSLD/UBE techniques, where by general anesthesia would also be required.

Fusion was promoted using a hydroxyapatite graft placed within the disc space and also inside the cage. Endplate preparation was similar to that described for standard TLIF through the traditional posterolateral approach, as the telescopic access instrumentation can be moved around 360° within the disc providing for clear-cut end plate preparation under direct visualization.

As assessed using the VAS scoring system, recovery of patients following surgery was found to be fast and satisfactory in all cases as mean VAS improved from 6.64 to 2.94 in 24 h after surgery (statistically significant with P = 0.0061). One major cause of quick pain relief was the increase in the size of the foramen allowing for breathing space to the root apart from decompression from the removal of the disc.

This study published here is currently ongoing as patients with a minimum of 6-month follow-up were only included in the study. The author would like to appeal to his readers to take into account the nonrandomized nature of the study.

Conclusions

The presented technique of EKLIF is a promising modality for the management of degenerative disc disease with or without instability, and patients with spondylodiscitis whereby fusion is necessary and also patients requiring a redo procedure benefit with this modality of fusion as a pathway for cage placement and decompression are natural and without any scar tissue thereby reducing complications associated with traditional redo spine surgeries.

Acknowledgment

I am thankful to all my patients who believed in me to undergo this novel technique. I also thank my mentor Dr. Malcolm Pestonji Sir who introduced me to this world of Spine endoscopy and guided me during my initial learning curve.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

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