Long-Term Outcome of Patients Undergoing Microscopic Lumbar Spinous Process-Splitting Laminectomy

Hiroshi Nomura,Junichi Arima,Yoshikazu Yanagisawa

doi:10.4172/2165-7939.1000343

Abstract

Microscopic lumbar spinous process–splitting laminectomy (LSPSL) has been previously reported as the least invasive surgery for patients with lumbar spinal canal stenosis (LSS). An 18-mm diameter tubular retractor was inserted between the split spinous processes and complete microscopic laminectomy performed in single-level decompressions. A cervical retractor was used to open the caudal parts of the individual halves of the spinous process through a single incision in multi-level decompressions. In this study, we examined long-term outcomes of patients undergoing microscopic LSPSL. Overall, 119 patients with a follow-up longer than 24 months were included in the study. All patients were divided into two groups: 1) the slip group, which included patients with spondylolisthesis-type LSS, and 2) the nonslip group, which included patients with spondylosis-type LSS. The clinical outcomes were evaluated using the Japanese Orthopedic Association score and improvement rate. The slip and instability rates were measured using radiographic imaging findings of the sagittal plane in patients in the slip group. Computed tomography was used to assess bony union of the split spinous process. Magnetic resonance imaging was used to evaluate signal changes of the multifidus muscle at different levels of LSPSL decompression. After LSPSL, pre-operative symptoms were improved with a significant difference in the Japanese Orthopedic Association score. The overall improvement rate was 62.2%; however, it was 48.6% in patients older than 79 years. No significant difference was seen in the slip or instability rate before and after LSPSL. The bony union rate of the split spinous process at the site between the process and the vertebral arch was 79.5%. Post-operative magnetic resonance imaging findings demonstrated a slight amount of fat infiltration in the multifidus muscles after LSPSL. In conclusion, the long-term outcome of patients undergoing LSPSL is satisfactory for a minimally invasive decompression surgery.

Highlights

Lumbar spinal stenosis (LSS) is caused by a gradual narrowing of the spinal canal
Various minimally invasive laminectomies have recently been introduced in patients with LSS, including bilateral decompression via the unilateral approach using a microendoscope and tubular retractor [1,2,3], lumbar muscle–preserving interlaminar decompression [4], and lumbar spinous process–splitting laminectomy (LSPSL) [5,6,7]
1 patient was treated with conventional laminectomy at the same level of the LSPSL, because of consequential lumbar disc herniation after LSPSL

Summary

Introduction

Lumbar spinal stenosis (LSS) is caused by a gradual narrowing of the spinal canal. It is associated with compression of the dural tube and spinal nerve root, and degenerative alteration in the lumbar spine. Various minimally invasive laminectomies have recently been introduced in patients with LSS, including bilateral decompression via the unilateral approach using a microendoscope and tubular retractor [1,2,3], lumbar muscle–preserving interlaminar decompression [4], and lumbar spinous process–splitting laminectomy (LSPSL) [5,6,7]. Of these procedures, we previously reported the clinical outcomes of patients undergoing microscopic LSPSL and found that it was the most minimally invasive surgery for patients with LSS [8]. We compared two groups of patients with excellent or fair clinical outcomes, focusing on factors that may influence clinical improvement, including age at the time of surgery, number of decompression levels, operative time, and existence of slipped vertebra; no apparent factors was found

Methods

Results

Conclusion