Tubular surgery with the assistance of endoscopic surgery via midline approach for lumbar spinal canal stenosis: a technical note.

PURPOSE: We devised a tubular surgery with the assistance of endoscopic surgery via midline approach to the spinal canal to preserve the bilateral facet joints and the paravertebral muscles when treating lumbar spinal canal stenosis. We report details of this operative procedure.
METHODS: A 2-cm incision is made in the skin in the midline of the intervertebral level to be decompressed. The spinous process on the cranial side is partially excised, and incisions along the ligament fiber are made in the midline of the supraspinous and interspinous ligaments to expose the ligamentum flavum. After the lamina and the inferior parts of the bilateral facet joints are adequately excised, the microendoscopic discectomy system is inserted. With this procedure, no muscular tissue is seen in the surgical site. The portal approach is small, but if full advantage is taken of the spinal microendoscope's merits, the bilateral facet joints are preserved and wide decompression of deep parts is possible. The microendoscope is positioned above the spinal canal to provide a good symmetrical field of view to enable easy anatomical orientation.
RESULTS: Bilateral intervertebral joints were satisfactorily preserved in ten patients who received this surgery. All became ambulatory on the day after surgery and the clinical results remained favorable 3 years after the operation.
CONCLUSION: Tubular surgery with the assistance of endoscopic surgery via a midline approach is a minimally invasive surgical procedure with favorable results that enables preservation of paravertebral muscles and bilateral facet joints.