Microendoscopic Decompression Surgery for Lumbar Spinal Canal Stenosis via the Paramedian Approach: Preliminary Results

The objective of this study was to evaluate the efficacy of a microendoscopic spinal decompression surgical technique using a novel approach for the treatment of lumbar spinal canal stenosis (LSCS). The following modifications were made to the conventional microendoscopic bilateral decompression via the unilateral approach: the base of the spinous process was first resected partially to secure a working space, so as not to separate the spinous process from the lamina. The tip of the tubular retractor was placed at the midline of the lamina, where laminectomy was performed microendoscopically. A total of 126 stenotic levels were decompressed in 70 patients. The mean operating time per level was 77.0 minutes, and the mean intraoperative blood loss per level was 15.0 mL. There were no dural tears or neurological injuries intraoperatively. Fracture of the spinous process was detected postoperatively in two patients, both of whom were asymptomatic. All patients could be followed up for at least 12 months. Their median Japanese Orthopaedic Association (JOA) score improved significantly from 16 points preoperatively to 27.5 points after the surgery (p < 0.001). The case series showed that the modifications of the technique improved the safety and ease of performance of the microendoscopic decompression surgery for LSCS.