Clin Orthop Surg.  2018 Dec;10(4):508-512. 10.4055/cios.2018.10.4.508.

Unilateral Biportal Endoscopic Spinal Surgery Using a 30° Arthroscope for L5–S1 Foraminal Decompression

• Kim JE
• Choi DJ

• KMID: 2426538
• DOI: http://doi.org/10.4055/cios.2018.10.4.508

Abstract

Foraminal decompression using a minimally invasive technique to preserve facet joint stability and function without fusion reportedly improves the radicular symptoms in approximately 80% of patients and is considered one of the good surgical treatment choices for lumbar foraminal or extraforaminal stenosis. However, proper decompression was not possible because of the inability to access the foramen at the L5-S1 level due to prominence of the iliac crest. To overcome this challenge, endoscopy-based minimally invasive spine surgery has recently gained attention. Here, we report the technical skills required in unilateral extraforaminal biportal endoscopic spinal surgery using a 30° arthroscope to enable foraminal decompression at the L5-S1 level. Two 0.8-cm portals were created 2 cm lateral from the lateral border of the pedicles at the L5-S1 level. After sufficient working space was made, half of the superior articular process (SAP) in the hypertrophied facet joint was removed using a high-speed burr and a 5-mm wide osteotome, whereas the remaining inside part of the SAP was removed using a Kerrison punch and pituitary punch. The foraminal ligamentum flavum should be removed to inspect the conditions of the L5 exiting root and disc. Removing of the extruded disc could decompress the L5 root. The extraforaminal approach using a 30° arthroscope is considered a minimally invasive alternative technique for decompressing foraminal stenosis at the L5-S1 level that preserves facet stability and provides symptomatic relief.

Keyword

Arthroscope; Spinal stenosis; Lumbosacral region; Endoscopes

MeSH Terms

Arthroscopes*
Constriction, Pathologic
Decompression*
Endoscopes
Humans
Ligamentum Flavum
Lumbosacral Region
Spinal Stenosis
Spine
Zygapophyseal Joint

Figure

• 

  Fig. 1 (A) Creating an extraforaminal working space. A schematic drawing on the right-side approach (left). An endoscopic view (right) showing the surgical anatomy, so-called “Half-and-Half” view. Partial resection of the tip of the superior articular process (SAP) should be fully performed to expose the half view of the cortical surface of the junction of transverse process (TP) and pedicle and the other half view of the cancellous surface of the SAP. This space of view enough to decompress the exiting root should be needed. (B) There are several bleeding foci (asterisks) at center, 10, 2, and 6 o'clock. (C, D) The difference of 0° arthroscopic and 30° arthroscopic views. The 30° arthroscopy is more advantageous for obtaining the inside view (D) than the 0° arthroscopy (C). It is more vertically rotated to the vertebra in the 12 o'clock direction for closer approach to the pedicle.

• 

  Fig. 2 Subpedicular decompression and unroofing of the exiting root. (A) Subpedicular cortical, thickening (dotted line) could compress the exiting root at the transverse process (TP) and pedicular junction. (B) Subpedicular corticotomy was performed using a ventral curved pedicular chisel. (C) Unroofing of the exiting root should be checked with sufficient proximal free space between the root and distal area of the TP using a freer and medially under the TP and pedicular junction using a 5-mm-thick curette (D).

• 

  Fig. 3 A case of 53-year-old male patient with L5–S1 foraminal stenosis on the left side. (A) Preoperative T2-weighted magnetic resonance imaging (MRI) sagittal view showing grade 2 foraminal stenosis with a decreased disc height. (B) Postoperative T2-weighted MRI sagittal view showing a widened foramen after foraminotomy using biportal endoscopic spinal surgery. (C) The L5 exiting root was compressed by the distal spur (asterisk) of the transverse process (TP) at the TP and pedicular junction and the surface of the root was seen covered by fibrous degenerative tissue with embedded perineural vessels on the root. (D) The proximal surface of the root should be fully decompressed after resection of the spur of the distal TP and the root should be in unroofed state. (E) The 0° arthroscopic view of the outlet of the root (asterisk) did not show the proximal curved part of the root under the pedicle. (F) The 30° arthroscopic view showed the deeper inner side for inspection of the corner under the pedicle.

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