Clin Orthop Surg.  2018 Dec;10(4):439-447. 10.4055/cios.2018.10.4.439.

Clinical and Radiological Outcomes of Foraminal Decompression Using Unilateral Biportal Endoscopic Spine Surgery for Lumbar Foraminal Stenosis

• Kim JE
• Choi DJ
• Park EJ

• KMID: 2426529
• DOI: http://doi.org/10.4055/cios.2018.10.4.439

Abstract

BACKGROUND
Since open Wiltse approach allows limited visualization for foraminal stenosis leading to an incomplete decompression, we report the short-term clinical and radiological results of unilateral biportal endoscopic foraminal decompression using 0° or 30° endoscopy with better visualization.
METHODS
We examined 31 patients that underwent surgery for neurological symptoms due to lumbar foraminal stenosis which was refractory to 6 weeks of conservative treatment. All 31 patients underwent unilateral biportal endoscopic far-lateral decompression (UBEFLD). One portal was used for viewing purpose, and the other was for surgical instruments. Unilateral foraminotomy was performed under guidance of 0° or 30° endoscopy. Clinical outcomes were analyzed using the modified Macnab criteria, Oswestry disability index, and visual analogue scale. Plain radiographs obtained preoperatively and 1 year postoperatively were compared to analyze the intervertebral angle (IVA), dynamic IVA, percentage of slip, dynamic percentage of slip (gap between the percentage of slip on flexion and extension views), slip angle, disc height index (DHI), and foraminal height index (FHI).
RESULTS
The IVA significantly increased from 6.24°± 4.27° to 6.96°± 3.58° at 1 year postoperatively (p = 0.306). The dynamic IVA slightly decreased from 6.27°± 3.12° to 6.04°± 2.41°, but the difference was not statistically significant (p = 0.375). The percentage of slip was 3.41% ± 5.24% preoperatively and 6.01% ± 1.43% at 1-year follow-up (p = 0.227), showing no significant difference. The preoperative dynamic percentage of slip was 2.90% ± 3.37%; at 1 year postoperatively, it was 3.13% ± 4.11% (p = 0.720), showing no significant difference. The DHI changed from 34.78% ± 9.54% preoperatively to 35.05% ± 8.83% postoperatively, which was not statistically significant (p = 0.837). In addition, the FHI slightly decreased from 55.15% ± 9.45% preoperatively to 54.56% ± 9.86% postoperatively, but the results were not statistically significant (p = 0.705).
CONCLUSIONS
UBEFLD using endoscopy showed a satisfactory clinical outcome after 1-year follow-up and did not induce postoperative segmental spinal instability. It could be a feasible alternative to conventional open decompression or fusion surgery for lumbar foraminal stenosis.

Keyword

Spinal stenosis; Endoscopic surgical procedure; Minimally invasive surgical procedures; Endoscopy

MeSH Terms

Constriction, Pathologic*
Decompression*
Endoscopy
Follow-Up Studies
Foraminotomy
Humans
Minimally Invasive Surgical Procedures
Spinal Stenosis
Spine*
Surgical Instruments

Figure

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  Fig. 1 Description of disc height index (B / A) and foraminal height index (C / A). A: vertebral body height measured at the midpoint of the body, B: disc height measured at the midpoint of the disc space, C: foraminal height measured as the largest distance between two adjacent pedicles.

• 

  Fig. 2 (A) Surgical instruments used during surgery. Root retractor, pituitary forceps, three chisels with various angles, cannula for water outflow, curved and straight curettes, and a dilator (from left to right). (B) Schematic anatomy of the foraminal zone of the lumbar spine. Note the pathway of radicular artery and the shape of superior articular process. (C) Intraoperative image: superior articular process being removed using a chisel. (D) Intraoperative image: nerve root exposed after removal of the superior articular process. SAP: superior articular process, LF: ligamentum flavum.

• 

  Fig. 3 Change of visual analogue scale score for back (A) and leg (B) from preoperative (Preop) to 3-month and 1-year postoperative assessments.

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  Fig. 4 (A) Change of Oswestry disability index (ODI) from preoperative (Preop) to 3-month and 1-year postoperative assessments. (B) Results according to modified Macnab criteria at 1 year postoperatively.

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  Fig. 5 Magnetic resonance images of one patient. (A) Preoperative parasagittal T1-weighted image of the left foramen. Note the compression of L5 nerve root. (B) Preoperative axial T2-weighted image. (C) Postoperative parasagittal T1-weighted image showing widened foraminal space for L5 nerve root. (D) Postoperative axial T2-weighted image. Note the removal of superior articular process and relatively widened left foraminal space.

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  Fig. 6 A case with spondylolytic spondylolisthesis with foraminal stenosis. Preoperative flexion (A) and extension (B) images. Postoperative flexion (C) and extension (D) images.

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