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

Our research focuses on unilateral bipolar endoscopy UBE for spinal degenerated diseases. The traditional UBE technique with two porters on one side can achieve unilateral laminectomy for bilateral decompression, ULBD, and therefore show favorable clinical outcomes. Here, we try to improve this technique to make it more efficient and safer.

The UBE technique has been increasingly used in spinal decompression or discectomy as a new endoscopic technique. The UBE technique recently has been proved to offer similar clinical outcomes compared to microdiscectomy by two randomized controlled trials. High resolution spinal endoscopes, as well as some special surgical tools suitable for endoscopic surgery, including operating tools and radial frequency abrasion tools have accelerated the development of spinal endoscopic surgery.

Besides navigation techniques are also helpful to arrange spinal endoscopic surgery. For the conventional UBE technique, it is challenging to perform ventral neuro decompression or discectomy at one side when there is bilateral recess stenosis or disc herniation. Although bilateral surgery can be performed, it will significantly prolong the surgical time, increase breathing, and the risk of dural tears.

For the case of lumbar spinal stenosis, combined with contralateral disc herniation, we established a third channel assist unilateral bipolar endoscopic technique to perform the controlled discectomy, which allows for the vertical entries into disc space and completely removes herniated disc fragments. The contralateral third channel is vertical to the lumbar spine in the T-UBE technique. In this way, the surgical tools can access deep into the disc space and remove all fragments, thereby reducing recurrence rate, and avoiding dural injury.

Compared to the traditional two channel UBE technique, the T-UBE technique enables more efficient removal of the contralateral herniated disc and reduces risk of dural sac injury. Also, T-UBE decreases soft tissue injury by avoiding two side UBE surgery. To begin, prepare for the endoscopic surgery procedure.

After inserting a 30-degree endoscope via the viewing channel, insert the surgical instruments and a radio frequency ablation blade via the working channel to remove the soft tissue on the laminar surface. Remove the soft tissue until the exposure of the lower edge of the L4 lamina, the ligamentum flavum, and the medial edge of the ipsilateral L4/5 facet joint. This establishes the endoscopic operating space.

Then, using a 3.5-millimeter high-speed drill operating at 8, 000 rotations per second, remove the ipsilateral lower part of the L4 lamina and the upper part of the L5 lamina. Additionally, use Kerrison punches to remove the medial inferior facet until the ligamentum flavum is fully mobilized. Next, separate the ligamentum flavum from the dural sac and gradually remove it from the cranial to the caudal end with Kerrison punches or forceps.

Then, carefully remove the medial facet joint of the L4/5 and the hyperplastic facet joint bone with punches or by using a soft tissue protection drill until the traversing nerve root is completely decompressed. Remove the base of the L4 spinous process with a drill operating at 8, 000 rotations per second and adjust the working channel obliquely toward the contralateral spinal canal. Undercut the medial part of the contralateral L4 inferior facet.

Then, fully expose the contralateral ligamentum and remove it using four-millimeter Kerrison bunches until adequate dorsal neural decompression. Use a blunt nerve hook to retract and protect the thecal sac and contralateral traversing nerve root or L5.Then, expose the contralateral herniated disc fragment. Then, insert forceps or other instruments vertically into the contralateral disc space and remove the herniated disc tissues through the third channel.

Finally, use a blunt nerve hook to explore the dural sac and bilateral nerve roots to ensure a sufficient spinal decompression. The T-UBE technique was used for the surgical treatment of lumbar spinal stenosis and left-sided lumbar disc herniation at L4/5. A comparison of pre and postoperative CT showed adequate bilateral decompression at the L4/5 level.

Also, postoperative MRI showed adequate bilateral decompression at the L4/5 level, indicating successful removal of the contralateral disc herniation, no compression at the dural nerve, and increased dural sac area. Moreover, the visual analog scale scores pertaining to low back pain and leg pain were reduced after surgery and throughout the postoperative follow up. Similarly, the shifts in Oswestry disability index scores reduced post-surgery, indicating a successful procedure.