Endoscopic Ventral Decompression for Spinal Stenosis with Degenerative Spondylolisthesis by Partially Removing Posterosuperior Margin Underneath the Slipping Vertebral Body: Technical Note and Outcome Evaluation

Background

Decompression alone is a treatment option in patients with lumbar spinal stenosis (LSS) and degenerative lumbar spondylolisthesis (DLS). This study aims to describe the procedure of percutaneous transforaminal endoscopic ventral decompression technique and to demonstrate the clinical outcomes.

Methods

Two years of retrospective data were collected from 26 patients with predominant unilateral leg pain caused by LSS and low-grade DLS (Meyerding grades I and Ⅱ). All patients underwent endoscopic ventral decompression by removing the posterosuperior margin underneath the slipping vertebral body, combined with dorsal decompression without excessive resection of facet joints. The surgical outcomes were assessed using the visual analog scale (VAS), Oswestry Disability Index (ODI), modified MacNab criteria, and walking distance improvement evaluation.

Results

The mean age of the 18 women and 8 men was 69.2 years. The mean preoperative ODI and VAS of the leg and the back scores were 64.7 ± 8.1, 7.0 ± 1.4, and 3.0 ± 1.2, respectively. All mean scores improved postoperatively to 31.4 ± 5.6, 2.4 ± 1.1, and 1.7 ± 1.1 at the final follow-up. In 88.5% of cases, patients' estimated walking distance improved. The outcomes of the modified MacNab criteria showed that 81.3% of patients obtained good-to-excellent rate. There were no statistically significant differences between the percent slip of spondylolisthesis before surgery and at the end of follow-up.

Conclusions

Based on the initial short-term follow-up results, transforaminal endoscopic ventral decompression by partially removing the posterosuperior margin underneath the slipping vertebral body, combined with dorsal decompression, might be an efficient alternative treatment for leg dominant symptoms in patients with LSS and low-grade DLS.

Introduction

Degenerative lumbar spondylolisthesis (DLS), a common spinal disorder, was initially described during the first half of the 20th century.¹ This pathologic condition eventually leads to narrowing of the spinal canal and foramen. Because of the compression of cauda equina nerve and nerve root, patients often present signs and symptoms consistent with neurogenic claudication and radiculopathy. Surgery can be performed on symptomatic patients who fail to undergo nonsurgical treatment. Traditionally, decompression with instrumented fusion surgical procedures is performed for patients with symptomatic nerve root compression with DLS. However, some clinical studies have shown that instrumental fusion during decompression does not lead to better outcomes for patients with DLS with lumbar spinal stenosis (LSS) compared with decompression alone surgery.² It is generally known that the progress of slippage decreases and restabilization occurs over the natural history of DLS.³ In recent years, minimally invasive spinal decompression procedures without instrumented fusion have been developed. This decompression technique may not increase the progress of slippage during the natural course. Minimally invasive decompression without instrumented fusion is another alternative treatment in patients with DLS with predominant leg pain.⁴

Percutaneous transforaminal endoscopic technique, an ultra-minimally invasive technique, has become increasingly popular in surgery of patients with lumbar degenerative diseases.⁵ Endoscopic treatment has been introduced as an effective treatment option not only in patients with lumbar disk herniation, but also in the pathologic condition of LSS.⁶ The endoscopic procedure has many advantages, for instance, progression under local anesthesia and rapid recovery.⁷ Compared with the traditional open approach, transforaminal endoscopic techniques could preserve the biomechanical structure of the affected segment and have only a very minor effect on spinal stability.⁸ In light of this, percutaneous transforaminal endoscopic decompression has little impact on segmental instability and has little possibility of influencing the natural course of LDS. It is speculated that if this procedure is performed, the degree of preoperative slippage does not need to be considered in the selection of fusion criteria.

To obtain a full-scale and thorough endoscopic nerve decompression, both ventral and dorsal nerve decompression should be ensured. In the DLS condition, because of degenerative disk disease and the degenerative facet osteoarthritis, one lumbar vertebra slips relative to the adjacent one. Correspondingly, a posterosuperior protruded compression underneath the slipping vertebral body is presented in the lumbar spinal canal, which cannot be ignored as a potential source of stenosis of the spinal canal.⁹ Therefore, spinal canal stenosis is caused both by anterior and posterior compression. The dorsal decompression alone procedure needs excessive resection of the facet joint. However, excessive facet resection might cause fracture of the superior facet and iatrogenic postoperative segmental instability. Therefore, we think a full-scale nerve decompression can be obtained by simultaneous ventral and dorsal decompression for the DLS condition. This surgical method has its advantages. Adding endoscopic resection of the posterosuperior margin underneath the slipping vertebral body could enlarge the lumbar spinal canal without excessive facet resection. The aim of this study is to assess the outcome of this ventral and dorsal endoscopic decompression technique for LSS in patients with low-grade (Meyerding grades I and Ⅱ) DLS with predominant leg pain.