Postoperative outcome after modified unilateral-approach microendoscopic midline decompression for degenerative spinal stenosis

OBJECT: The object of this study was to assess the feasibility and efficacy of a novel, minimally invasive spinal surgery technique to correct degenerative lumbar spinal stenosis involving a modified unilateral-approach microendoscopic midline decompression. METHODS: In this prospective study, 41 patients with lumbar stenosis were randomly assigned to undergo either a novel, median-approach microendoscopic laminectomy (20 patients) or a conventional laminectomy (21 patients). Spinal anteroposterior diameter, cross-sectional area, lateral recess distance, spinal stability, postoperative back pain, functional outcomes, and muscle trauma were evaluated. Follow-up ranged from 16 to 24 months, with a mean of 17.8 months for the novel procedure group and 18.6 months for the conventional laminectomy group. RESULTS: Compared with patients in the conventional laminectomy group, patients who received the novel procedure had a reduced mean duration of hospital stay, a lower mean creatine phosphokinase muscular-type isoenzyme level, a lower visual analog scale score for back pain at 1-year follow-up, and a faster recovery rate. These patients also had less mean blood loss compared with the conventionally treated group. Satisfactory neurological decompression and symptom relief were achieved in 90% of these patients. There was no significant clinical difference compared with the conventional laminectomy group's results. There was no evidence of spinal instability in any patient, and no patient required a follow-up conventional laminectomy. CONCLUSIONS: This novel procedure provides effective spinal decompression. Although this method requires more operating time than a conventional method, it requires only minimal muscle trauma and spinal stability maintenance, and allows for early mobilization. This shortens the hospital stay, reduces postoperative back pain, and leads to satisfactory neurological and functional outcomes. Moreover, with the midline approach, decompression was accomplished without compromising the facet joints, even with a narrow width of lamina.