Clinical and Radiological Outcomes of Unilateral Biportal Endoscopic Decompression by 30° Arthroscopy in Lumbar Spinal Stenosis: Minimum 2-Year Follow-up

BACKGROUND: Open microscopic laminectomy has been the standard surgical method for degenerative spinal stenosis without instability till now. However, it is associated with complications such as paraspinal muscle injury, excessive bleeding, and wound infection. Several surgical techniques, including microendoscopic decompression, have been introduced to solve these problems. METHODS: Authors analyzed retrospectively 55 patients presenting with neurological symptoms due to degenerative lumbar spinal stenosis refractory to conservative treatment. Patients with foraminal stenosis requiring foraminal decompression were excluded. Two or three portals were used for each level. One portal was used for viewing purpose and the others for instrument passage. Unilateral laminotomy was followed by bilateral decompression under the view of 30° arthroscopy. Clinical outcomes were evaluated using modified Macnab criteria, Oswestry disability index (ODI), and visual analogue scale (VAS). Postoperative complications were checked during the 2-year follow-up. Plain radiographs before and after surgery were compared to analyze the change of disc height decrement and alignment. RESULTS: ODI scores improved from 67.4 ± 11.5 preoperatively to 19.3 ± 12.1 at 2-year follow-up (p < 0.01). VAS scores of the leg decreased from 7.7 ± 1.5 to 1.7 ± 1.5 at the final follow-up (p < 0.01). Per the modified Macnab criteria, 81% of the patients improved to good/excellent. No cases of infection occurred. The intervertebral angle was significantly reduced from 6.26°± 3.54° to 5.58°± 3.23° at 2 years postoperatively (p = 0.027) and the dynamic intervertebral angle changed from 6.54°± 3.71° to 6.76°± 3.59°, which was not statistically significant (p = 0.562). No significant change in slippage was observed (3.76% ± 5.01% preoperatively vs. 3.81% ± 5.28% at the final follow-up [p = 0.531]). The dynamic percentage slip did not change significantly, from 2.65% ± 3.37% to 2.76% ± 3.71% (p = 0.985). However, intervertebral distance decreased significantly from 10.43 ± 2.23 mm to 10.0 ± 2.24 mm (p = 0.000). CONCLUSIONS: Full endoscopic decompression using a 30° arthroscopy demonstrated a satisfactory clinical outcome at the 2-year follow-up. This technique reduces wound infection rate and did not bring about postoperative segmental spinal instability. It could be a feasible alternative to conventional open microscopic decompression or fusion surgery for degenerative lumbar spinal stenosis.

Endoscopic Spine Surgery

Surgical treatment of the degenerative disc disease has evolved from traditional open spine surgery to minimally invasive spine surgery including endoscopic spine surgery. Constant improvement in the imaging modality especially with introduction of the magnetic resonance imaging, it is possible to identify culprit degenerated disc segment and again with the discography it is possible to diagnose the pain generator and pathological degenerated disc very precisely and its treatment with minimally invasive approach. With improvements in the optics, high resolution camera, light source, high speed burr, irrigation pump etc, minimally invasive spine surgeries can be performed with various endoscopic techniques for lumbar, cervical and thoracic regions. Advantages of endoscopic spine surgeries are less tissue dissection and muscle trauma, reduced blood loss, less damage to the epidural blood supply and consequent epidural fibrosis and scarring, reduced hospital stay, early functional recovery and improvement in the quality of life & better cosmesis. With precise indication, proper diagnosis and good training, the endoscopic spine surgery can give equally good result as open spine surgery. Initially, endoscopic technique was restricted to the lumbar region but now it also can be used for cervical and thoracic disc herniations. Previously endoscopy was used for disc herniations which were contained without migration but now days it is used for highly up and down migrated disc herniations as well. Use of endoscopic technique in lumbar region was restricted to disc herniations but gradually it is also used for spinal canal stenosis and endoscopic assisted fusion surgeries. Endoscopic spine surgery can play important role in the treatment of adolescent disc herniations especially for the persons who engage in the competitive sports and the athletes where less tissue trauma, cosmesis and early functional recovery is desirable. From simple chemonucleolysis to current day endoscopic procedures the history of minimally invasive spine surgery is interesting. Appropriate indications, clear imaging prior to surgery and preplanning are keys to successful outcome. In this article basic procedures of percutaneous endoscopic lumbar discectomy through transforaminal and interlaminar routes, percutaneous endoscopic cervical discectomy, percutaneous endoscopic posterior cervical foraminotomy and percutaneous endoscopic thoracic discectomy are discussed.