Tubular surgery with the assistance of endoscopic surgery via a paramedian or midline approach for lumbar spinal canal stenosis at the L4/5 level

Background: Lumbar spinal canal stenosis surgery has recently improved with the use of minimally invasive techniques. Less invasive procedures have emerged, and microendoscopic decompression through smaller incisions is frequently performed. Tubular surgery with the assistance of endoscopic surgery procedures has led to particularly remarkable changes in surgery, with reduced tissue trauma and morbidity. Purpose: The purpose of this study was to compare the clinical outcomes of two different minimally invasive decompressive surgical techniques (microendoscopic bilateral decompression surgery using the unilateral approach [microendoscopic laminectomy (MEL)] and microendoscopy-assisted muscle-preserving interlaminar decompression (MILD; ME-MILD)) using spinal endoscopy for lumbar spinal canal stenosis measured using a visual analog scale (VAS), the Japanese Orthopedic Association (JOA) score, and the JOA Back Pain Evaluation Questionnaire (JOABPEQ), which is based on a patient-oriented scoring system. Study design: This study was a retrospective review of prospectively collected surgical data. Methods: The study included 81 patients (MEL 39 patients, 20 men and 19 women, mean age 68.9 years; and ME-MILD 42 patients, 22 men and 20 women, mean age 73.1 years) with lumbar spinal stenosis (LSS). The indications for surgery were moderate-to-severe stenosis, persistent neurological symptoms, and failure of conservative treatment over 3 months, with a JOA score under 15 points or intermittent claudication at 100 m. This study included patients having LSS at a single vertebral level (L4/5). Results: Low back pain, buttock-leg pain, and numbness were significantly improved in terms of the VAS score from 3 months with both MEL and ME-MILD. In all periods, JOA scores over 3 years of follow-up were significantly higher than those obtained before surgery with both MEL and ME-MILD, and there were improvements of low back pain and walking function. Conclusions: These observations demonstrate that ME-MILD is a safe and very effective minimally invasive technique for degenerative LSS, similar to MEL.