The Third Channel-Assisted Unilateral Biportal Endoscopic Technique for Lumbar Spinal Stenosis Combined with Contralateral Disc Herniation

Summary

Here, we present the third channel-assisted UBE technique, which allows for the vertical removal of herniated disc fragments. This technique can effectively address the limitations of traditional UBE techniques. This article will systematically elaborate on this procedure.

Abstract

Unilateral biportal endoscopic (UBE) spine surgery is an emerging minimally invasive surgical (MIS) technique that has gained popularity for treating lumbar spinal stenosis, particularly in Eastern Asia. The traditional UBE technique, with two portals on one side, can achieve successful unilateral laminotomy for bilateral decompression (ULBD) and, therefore, demonstrates favorable clinical outcomes. However, in the case of lumbar spinal stenosis combined with contralateral disc herniation, it is very difficult to remove the contralateral disc herniation, especially the loose disc fragment within the deep disc. Here, a third channel of the traditional UBE technique was developed to do the discectomy within the ipsilateral endoscopic vision, with which the instruments can go vertically into the contralateral disc, allowing easy discectomy. This technique can not only achieve adequate decompression of the bilateral spinal canal but also effectively remove contralateral herniated disc fragments. This technique avoids performing another UBE procedure on the opposite side, which can potentially shorten the duration of the operation, minimize blood loss and tissue damage, and ensure sufficient neural decompression. This paper will introduce the indications and surgical operation procedures, as well as present a classical case report and follow-up data, to facilitate the application of the third channel-assisted UBE (T-UBE) technique for spine surgeons.

Introduction

In the field of spine surgery, minimally invasive spine surgical (MISS) techniques have evolved significantly in recent years, transitioning from open surgery to microscopic, microendoscopic, and endoscopic surgery. Endoscopic spine surgery is an advanced form of MISS technique that has been widely used to treat spinal diseases and achieve satisfactory clinical outcomes¹. Compared with traditional open surgery, it has the advantages of less tissue damage, less bleeding, quicker recovery, and fewer postoperative complications².

Endoscopic spine surgery can be performed using single or two portals. Unilateral biportal endoscopic (UBE) spine surgery is an innovative type of MISS technique that was first reported for performing lumbar discectomy in Argentina. It has since been refined to also perform decompression or fusion surgery in South Korea³. The surgical procedure of the UBE technique is similar to conventional open surgery. However, the UBE technique is less invasive and provides a clearer field of view compared to traditional open surgery^4,5.

The conventional UBE technique not only enables unilateral decompression but also achieves bilateral decompression for spinal stenosis^6,7. In 2019, Heo et al.⁸ reported that the UBE technique could significantly expand the stenotic dural areas through unilateral laminotomy for bilateral decompression (ULBD). This technique also preserved more of the ipsilateral facet joint by undercutting the medial facet joint, compared to conventional microscopic decompression. In 2021, Kim et al.⁹ described a new decompression procedure for UBE in cases of asymmetric spinal stenosis using a contralateral approach. The contralateral approach UBE technique was able to achieve adequate decompression of the contralateral recess and spinal stenosis. It had advantages such as better manipulative freedom, a more accessible target approach, and more facet preservation.

The advantage of the UBE technique is dorsal and lateral spinal decompression through the endoscopic ULBD procedure. However, It is challenging to perform ventral neural decompression or discectomy when there is bilateral recess stenosis or disc herniation. Although bilateral UBE can be performed, it will significantly prolong the operation time, increase intraoperative bleeding, and elevate the risk of dural injury. Here, a third channel was developed in the UBE technique to perform the discectomy within the same endoscopic field of view. This allows the instruments to be inserted vertically into opposite discs, making the discectomy process easier. This technique can not only achieve adequate decompression of the bilateral spinal canal but also effectively remove contralateral herniated disc fragments.

Protocol

The Institutional Review Board of the Third Affiliated Hospital at Sun Yat-sen University approved the protocols (ID:[2022]02-356-01). All included patients were required to sign an informed consent form.

1. Surgical indications

1. Include patients with lumbar spinal stenosis who have contra-lateral recess stenosis or disc herniation or who have contra-lateral neural compression.

2. Surgical method

1. Perform bilateral endoscopic spinal canal decompression via UBE-ULBD technique and endoscopic discectomy via T-UBE.

3. Preoperative procedure

1. Anesthesia and surgical position:
   1. Under general anesthesia, position the patient prone on a spinal frame, avoiding any discomfort. Flex the lumbar spine slightly to open up the interlaminar space.
      NOTE: General anesthesia with endotracheal intubation or combined spinal-epidural anesthesia is used for surgical procedures to minimize intraoperative pain.
2. Desired portals position (L4-5, for example):
   1. Obtain a standard anteroposterior (AP) X-ray view, and let the target intervertebral space be vertical to the ground in the X-ray lateral view by adjusting the surgical table.
   2. Mark the bilateral pedicles of L5 and the ipsilateral pedicle of L4. Draw a line along the midline of the L4/5 intervertebral disc and the posterior midline of the spine.
   3. On the ipsilateral side, mark two incisions 1.5 cm above and below the midline of the intervertebral disc for manipulation and endoscopic portal, respectively. Locate the third channel incision on the contra-lateral midline of the L4/5 intervertebral disc space.

4. Surgery procedure (L4-5, for example)

1. Sterilize the surgical site with iodine tincture and 75% alcohol, and prepare the site with waterproof drapes.
2. Establish UBE endoscopic channel and ipsilateral working channel.
   1. Insert two syringe needles from the medial edge of the line of the ipsilateral pedicle shadow, one at 15 mm cranial and the other at 15 mm caudal, to the midline of the L4/5 intervertebral disc. The inserted needles will form a triangle and meet at the L4/5 interlaminar.
   2. Then, make two 8-10 mm longitudinal skin incisions for endoscopic and manipulated portals based on the location of the aforementioned needles.
   3. After dissecting the extralaminal soft tissue with a curette, insert serial dilators to expand the surgical field. Then, establish the endoscopic channel and working channel, converging along the sublaminar edge.
3. Establish endoscopic operating space (Figure 1A-C)
   1. Insert a 30-degree endoscope via the viewing channel, connected to a continuous gravity saline irrigation positioned 50-60 cm high above the patient.
   2. After that, insert the surgical instruments and a radiofrequency ablation blade via the working channel to remove the soft tissue on the laminar surface until exposure of the lower edge of the L4 lamina, the ligamentum flavum, and the medial edge of the ipsilateral L4/5 facet joint. Establish the endoscopic operating space.
4. Ipsilateral laminotomy and neural decompression (Figure 2A-D, Figure 3A-D)
   1. Remove the ipsilateral lower part of the L4 lamina, the upper part of the L5 lamina, and the medial inferior facet by a 3.5-mm high-speed drill (8000 rotations/s) and Kerrison punches until the ligamentum flavum is fully mobilized.
   2. Then, separate the ligamentum flavum from the dural sac and gradually remove it from the cranial to the caudal end with Kerrison punches or forceps.
   3. After that, carefully remove the medial facet joint of L4/5 and the hyperplastic facet joint bone with a soft-tissue protection drill or punches until the traversing nerve root is completely decompressed.
   4. Ensure that more than 50% of the medial facet is preserved, avoiding the possibility of spinal instability.
5. Contra-lateral dorsal neural decompression (Figure 4A-E)
   1. Remove the base of the L4 spinous process with a drill (8000 rotations/s) and adjust the working channel obliquely towards the contralateral spinal canal.
   2. Undercut the medial part of the contralateral L4 inferior facet, fully expose the contralateral ligamentum, separate from the dural sac, and remove it using Kerrison punches (4 mm) until adequate dorsal neural decompression.
6. Contralateral third channel-assisted discectomy (Figure 5A-C, Figure 6A-E)
   1. Make an 8-mm longitudinal skin incision adjacent (5 mm) to the spinous process at the midline of the contralateral disc. Insert a K-wire, followed by serial dilators under endoscopic view, to establish the contra-lateral working channel.
   2. After the thecal sac and contra-lateral traversing nerve root (L5) are retracted and well protected, expose the contralateral herniated disc fragment. Then, insert forceps or other instruments vertically into the contra-lateral disc space and remove the herniated disc tissues through the third channel.
   3. At last, use a blunt nerve hook to explore the dural sac and bilateral nerve roots to ensure sufficient spinal decompression.
7. Place a drainage tube outside the lamina and suture each incision to complete the operation.
   NOTE: The surgical instruments used in the T-UBE technique are essentially the same as those used in the conventional UBE technique and traditional open spinal surgery. There is no need to purchase specialized instruments. T-UBE instruments include a 30-degree, 4-mm-diameter arthroscope, an endoscopic sheath, standard laminectomy instruments such as Kerrison punches, forceps, and nerve hooks, as well as a bipolar flexible radiofrequency probe, and a 3.5-mm radiofrequency electrode.

Results

The T-UBE technique will be demonstrated in a typical case. A 65-year-old male complained of low back pain with bilateral numbness in his lower limbs for 10 months. The numbness is more pronounced on the right side and is accompanied by intermittent claudication, which occurs after walking 50 m. The symptoms on the left side were relieved by analgesic and neurotrophic drug treatment, but the symptoms on the right side persisted. Physical examination revealed mild tenderness of the spinous process and pain upon percussion...

Discussion

The UBE technique is an innovative endoscopic surgery that has rapidly advanced in recent years for the treatment of spinal disorders¹². In contrast to PELD, UBE does not require specialized instruments and is similar to conventional surgical procedures. This may reduce costs and eliminate the need for extensive training, particularly for surgeons experienced in arthroscopic surgery¹³. Therefore, the UBE technique has been widely used for discectomy, spinal canal decompress...

Materials

Name	Company	Catalog Number	Comments
Bone dissector	Hengsheng Medical Instrument Co., Ltd.	PMT-BLQ001	Used for soft tissue expansion and laminar bone surface soft tissue stripping. Curved streamline design, better hand holding, one device and two uses, one end as soft tissue expansion, the other end as bone tissue dissection, fully expand and dissect the lamina and facet soft tissue.
Electric surgical equipment for osseous tissue	Viewall	VP7110	Used to grind off vertebral plate and partial facet bone; in the device channel, it is used for processing bone tissue; grind bone tissue at high speed, without damage to soft tissues such as nerve vessel; even grind close to nerve root, without damage to nerve; it is safer and faster.
Expandable Channel	Hengsheng Medical Instrument Co., Ltd.	PMT-KZG001	Perform channel dilation
Handle of scalpel	Hengsheng Medical Instrument Co., Ltd.	PMT-DB001	Used to Install scalpel
Mouth gag	Hengsheng Medical Instrument Co., Ltd.	PMT-KKQ001	Used to handle annulus breaks prior to disc
Nerve hook	Hengsheng Medical Instrument Co., Ltd.	PMT-LG001	Used for traction of nerve root in surgery; under endoscopic surgical field, pull apart and protect nerve root in instrument channel and can simultaneously enter other instruments for processing intervertebral disc.
Nucleus pulposus forceps	Hengsheng Medical Instrument Co., Ltd.	PMT-SHQ003	Used for clamping soft tissue and nucleus pulposus tissue of intervertebral disc during operation. Different angles and sizes allow easier grasping of soft tissue in various locations during surgery, and the finger loop design is ergonomic and easy to perform, along with gunshot forceps.
Osteotome	Hengsheng Medical Instrument Co., Ltd.	PMT-GZ001	During the operation, handle the lamina and facet, osteotomes with different angles and sizes can efficiently and flexibly chisel the facet and laminar bone
Radiofrequency electrode	GAOTONG	DZX-T2430-A160	Used for hemostasis ablation, cutting and cleaning soft tissue under endoscope during operation
Rongeur	Hengsheng Medical Instrument Co., Ltd.	PMT-YGQ002	During the operation, the laminar and facet bones were bitten and cut, the bone window was enlarged, and different sizes and angles were different. The bitewing mouth of the large incision easily bitewed off different bony tissues and calcified tissues, greatly saving the operation time, gun design, better hand holding sensation, and more forceful biting of bony tissues during the operation
Scalpel	Hengsheng Medical Instrument Co., Ltd.	PMT-SSD001	Used to cut the annulus fibrosus
Tissue Liberator	Hengsheng Medical Instrument Co., Ltd.	PMT-BLQ002	Used for stripping soft tissue in surgery, bidirectionally at different angles; used for stripping and separating mucosal tissue under instrument channel.