Full Endoscopic Interlaminar Approach for Paracentral L5-S1 Disc Herniation

Summary

Here, we present a protocol to describe the full endoscopic interlaminar approach (FEILA) technique, including every cutoff step required to reach technical proficiency. FEILA is a surgery with a relatively steep learning adaptation. Despite this, any surgeon capable of microdiscectomy can perform FEILA with enough practice and suitable patient selection.

Abstract

The full endoscopic interlaminar approach (FEILA) is a minimally invasive technique for lumbar discectomy. It has multiple advantages over other conventional discectomy methods, including less traumatization of the soft tissues, fewer complication rates (dural injury, bleeding), rapid rehabilitation, quick return to daily life activities, and preferable cosmetic results. FEILA is a surgery with a relatively steep learning adaptation. Endoscopic surgery is a closed tubular approach, and all surgical maneuvers are performed within a uniportal single working channel. Also, the technique has not yet been standardized and well-documented. Therefore, the early learning stages of this technique may not be easy for most surgeons. Despite these, FEILA is easy, and the operation length is comparable to and even shorter than other techniques of lumbar discectomy. FEILA for lumbar discectomy could be considered a safe and effective alternative procedure for paracentral L5-S1 disc herniation. Here, we describe the technique of FEILA, including every cutoff step required to reach technical proficiency for surgeons who want to start applying this approach.

Introduction

Lumbar degenerative disc disease is an anatomical and morphological change causing clinical complaints¹. Surgery is the appropriate treatment in cases that do not respond to conservative treatments². Conventional surgeries have been used, but they have disadvantages such as prolonged hospital stay, high amount of tissue damage, delayed mobilization, and risk of epidural fibrosis and instability. Because of these disadvantages, researchers have tried to develop less invasive methods. The full endoscopic (interlaminar-transforaminal) technique with posterolateral access evolved out of this².

Due to the lateral iliac blocks of the L5-S1 segment, the transforaminal approach is limited. However, the L5-S1 level usually has the widest interlaminar window and a sufficient interval for the endoscope to fit. FEILA provides a direct route for decompression at the L5-S1 level. Therefore, this article aims to enable surgeons who are trying this technique for the first time to learn the technique in more detail and faster.

FEILA is a minimally invasive method to decompress lumbar disc herniation under excellent visualization and continuous saline irrigation^3,4. FEILA is performed via a dilator placed through a small skin incision in the lumbar region. The dilator allows surgeons to place the working sleeve and endoscope over the dilator. Then, the surgeons use tools through the endoscope to perform a discectomy and decompression of the nerve. It has multiple advantages compared to conventional surgeries, including less traumatization of the soft tissues, fewer complication rates (less dural injury and bleeding), rapid rehabilitation, quick return to daily life activities, better cosmetic results, and a lower cost⁴.

FEILA is a surgery with a relatively steep learning adaptation. Because full endoscopic surgery is a closed tubular approach, all surgical maneuvers are performed within a uniportal single working channel⁵. In addition, the technique has not yet been standardized and well-documented. Therefore, the early learning stages of this technique may not be easy for most surgeons⁶. Despite these facts, the surgery is easy, and the operation length is comparable to and even shorter than other techniques of lumbar discectomy, especially at the L5-S1 level.

Surgical indications and contraindications for FEILA are evaluated after physical examination of the patients and neuroradiological imaging (X-ray and magnetic resonance imaging [MRI]) are performed. FEILA is indicated for sequestered or non-sequestered disc herniations (especially paracentral disc herniation), recurrent disc herniations after traditional or other minimally invasive methods, zygapophyseal joint cysts, and lateral bony and ligament spinal canal stenosis. FEILA is contraindicated for compressive intra- or extraforaminal pathologies, extensive central spinal canal stenoses, a pronounced bony shift in the interlaminar window and calcified discs, severe adhesion due to fibrotic tissue, fusions or instabilities in the spinal canal, cauda equina syndrome, weakness without pain, spondylodiscitis, and other severe spine infections^7,8,9.

Protocol

The study protocol was approved by the institutional review board of the Istanbul Faculty of Medicine. Written consent was obtained from the patients before the surgical procedure.

1. Preoperative procedures

1. Perform the procedure under general anesthesia with an anesthetist. Set the endoscopic and optic instruments, and C-arm devices in the operation room.
2. Ensure the following tools are available for the procedure; dilator, working sleeve, endoscope with a 20° viewing angle, Kerrison punch, ronguer, punch, tip control radioblator probe that applies a radiofrequency current of 4 MHz, fluid conrol irrigation, and suction pump devices.

2. Technical note

1. Position of patient
   1. Place the patient in a prone position (support the thorax and pelvis with pillows) with the hip and knee flexed to achieve a wider interlaminar space.
2. Preparing the surgical field
   1. Sterilize the lumbar region with iodine or chlorhexidine (10%).
   2. Use sterile sheets to outline the prepared surgical site.
   3. Drape the operation field and C-arm with a waterproof surgical drape.
3. Determine the entry point.
   1. Obtain an anteroposterior (AP) X-ray view and mark the interlaminar space at the L5-S1 level (Figure 1A).
      NOTE: The C-arm is a device that can rotate 360° around the patient and obtain anteroposterior (AP) and lateral X-ray views intraoperatively.
   2. Mark (with a sterile, surgical skin marker) as close to medial in the craniocaudal middle of the interlaminar window as possible for enough lateral access.
4. Incision
   1. Make a 10 mm skin incision as close to the midline as possible with a 20-blade.
   2. Check that the fascia of the paraspinal muscle has been passed.
5. Insertion of the dilator
   1. Insert the dilator through the incision and laterally advance until it reaches the facet joint (Figure 1B).
   2. Obtain a lateral and AP X-ray view with the C-arm to confirm that the tip of the dilator is at the desired level and facing toward the facet joint of the ipsilateral pathology.
6. Insertion of working sleeve
   1. Slide the working sleeve with the beveled opening toward the midline over the dilator.
   2. Obtain a lateral X-ray view with the C-arm to confirm that the tip of the working sleeve has reached the end of the dilator.
   3. Remove the dilator.
7. Introduce the endoscope.
   1. Introduce an endoscope with a continuous inflow of saline (0.9% sodium chloride) over the working sleeve until the interface of the ligamentum flavum and muscle (Figure 1C).
      NOTE: The flow rate is arranged by fluid control irrigation and suction pump devices. There is no specific rate flow. The surgeon can arrange the rate of flow to obtain optimum visualization.
   2. Perform the rest of the procedure with continuous irrigation. Fluid flow will keep the surgical field clear. Control any risk of bleeding with the fluid pressure and direct application of the cautery (RF 4 Mhz).
8. Exposure of ligamentum flavum
   NOTE: The first structures to be visualized after the endoscopic introduction should be at the interface of the ligamentum flavum and muscle.
   1. Remove the soft tissues using a rongeur until the ligament flavum is exposed (Figure 1D).
   2. Perform bone resection via a high-speed burr to achieve a wider interlaminar space if there is not a wide enough interlaminar window to fit the endoscope.
9. Resection of ligamentum flavum
   1. Tense the ligamentum flavum with the long side of the working sleeve.
   2. Separate the ligamentum flavum from the dura for a safer resection, as the dura is more prominent in the midline.
   3. Begin the ligamentum flavum resection from the medial side using a 5.4 mm punch.
   4. Control the cutting edge of the punch while the ligamentum flavum is being resected. Doing so otherwise risks a dural tear.
   5. Continue ligamentum flavum resection laterally until the lateral recess and pedicle are visualized to expose the nerve root and its lateral border (Figure 1E).
10. Discectomy
    1. Remove the epidural fat tissue totally using the rongeur for a clear view of the compression.
    2. Mobilize the nerve root medially using the dissector to relieve it from any adhesions.
    3. Rotate the long side of the working sleeve clockwise or counterclockwise to medialize the nerve root and expose the pathology (Figure 1F).
    4. Visualize the anterior epidural space, annular defect, disk interval, and end plates.
    5. Remove the migrated disc material and loosen the fragments under the annulus through the defect if they are present and visualized.
    6. Use the punch to open the posterior longitudinal ligament and the annulus fibrosis if there is a subligamentous protruding material.
    7. Use the rongeur to remove the disc material, after detecting the annular defect and disc material in both situations.
    8. Use the punch to obtain enough space if no annular defect is encountered or the annular defect is too narrow for sufficient removal.
    9. Evacuate the disc space with the rongeur or punch until achieving nerve root decompression.
    10. During the discectomy, do not perform excessive retraction, so as to prevent neural trauma. Intermittent release or de-rotation of the working sleeve is necessary to decrease neurological complications.
11. After the discectomy, coagulate the defect of the annulus by bipolar electrocautery for sealing and hemostasis purposes.
12. Achieve hemostasis in every procedure step with continuous fluid flow or bipolar electrocautery (RF 4 Mhz).
13. Remove the endoscope and working sleeve.
14. Close the incision with a single proline suture (2.0) without drainage.

3. Postoperative procedures and follow-up

1. The hospital stay is short, and mobilization is immediateon the day of surgery.
2. Discharge the patients the next day if there are no complaints.
   NOTE: Rehabilitation and physical therapy are not necessary. Analgesics and rehabilitative measures are not primarily necessary.
3. Recommend the patients to be admitted to an outpatient clinic in the 1^st and 4^th weeks.

Results

A 52-year-old male patient presented with low back pain radiating down his left leg without motor weakness for 6 months. The visual analog scale (VAS) score was 6/10 on the trunk and 8/10 on the left leg. The patient's symptoms were resolved and he was discharged the day after surgery. The postoperative follow-up VAS score was 2/10 on the trunk and 2/10 on the left leg. The preoperative and postoperative lumbar MRI of the patient showed total removal of the disc material by the full endoscopic interlaminar approach (

Discussion

The results of recent studies depict the possibility of sufficient decompression via FEILA; these results are equal to those of traditional methods. Also, the advantages of the significant relief of back pain, faster recovery after surgery (short period of hospital stay), fewer complications, lower recurrence rate, minimizing soft-tissue disruption (small incision, less muscle cutting, less blood loss), and reducing segment instability have been shown^10,1...

Materials

List of materials used in this article

Name	Company	Catalog Number	Comments
Burr Oval Ø 5.5 mm	RiwoSpine	899751505	PACK = 1 PC, WL 290 mm, with lateral protection
C-arm	ZIEHM SOLO		C-arm with integrated monitor
Dilator ID 1.1 mm OD 9.4 mm	RiwoSpine	892209510	For single-stage dilatation, TL 235 mm, reusable
Endoscope	RiwoSpine	892103253	20° viewing angle and 177 mm length with a 9.3 mm diameter oval shaft with a 5.6 mm diameter working channel
Kerrison Punch 5.5 mm x 4.5 mm WL 380 mm	RiwoSpine	892409445	60°, TL 460 mm, hinged pushrod, reusable
Punch Ø 3 mm WL 290 mm	RiwoSpine	89240.3023	TL 388 mm, with irrigation connection, reusable
Punch Ø 5.4 mm WL 340 mm	RiwoSpine	892409020	TL 490 mm, with irrigation connection, reusable
Radioablator RF BNDL	RiwoSpine	23300011
RF Instrument BIPO Ø 2.5 mm WL 280 mm	RiwoSpine	4993691	for endoscopic spine surgery, flexible insert, integrated connection cable WL 3 m with device plug to Radioblator RF 4 MHz, sterile, for single use
Rongeur Ø 3 mm WL 290 mm	RiwoSpine	89240.3003	TL 388 mm, with irrigation connection, reusable
Working Sleeve ID 9.5 mm OD 10.5 mm	RiwoSpine	8922095000	TL 120, distal end beveled, graduated, reusable