RESUMEN
OBJECTIVE: The minimally invasive spine surgery has become popular to reduce approach-related injury associated with the traditional spine surgery. The unilateral laminetomy and bilateral decompression(ULBD) using a microscopic tubular retractor system preserves interpedicular portion of the lamina, the spinous processes, supraspinous and interspinous ligamentous complex, contralateral facet and paraspinal musculature. The aim of this study is to evaluate the effectiveness of ULBD with microscope and tubular retractor system. METHODS: We retrospectively analyzed 24 patients who was diagnosed with lumbar spinal stenosis and treated with ULBD. The visual analogue scale(VAS) and oswestry disability index(ODI) to pain were checked for clinical assessment. We postoperatively observed a presence of spinal instability in flexion-extension radiographs. The cross sectional area (CSA) of dural sac was measured in the preoperative and postoperative magnetic resonance(MR) images. The mean follow up period was 18 months. RESULTS: The subjects were composed of 16 men and 8 women and average age was 67.4 years. Clinical improvement was assessed with VAS and ODI scale at last follow-up. The average VAS score of back pain was decreased from 3.6+/-1.3 to 1.7+/-0.9 after surgery(p<0.01). The average VAS score of leg pain also was decreased from 6.9+/-0.9 to 2.1+/-1.0 after surgery(p<0.01). Average ODI was decreased from 49.0+/-7.3 to 23.2+/-6.2(p<0.01). No patient developed spinal instability after operation on the flexion-extension radiographs. Postoperative CT and MR images showed bila- teral decompression by unilateral laminectomy. The mean dural CSA was significantly increased from 50.8+/-13.5mm2 to 130.5+/-16.5mm2(p<0.01). Complications were detected in two patients(dural tear in one and transient dysesthesia in 1 subject). CONCLUSIONS: ULBD using the microscopic retractor tubular system minimized trauma to posterior lumbar component with favorable clinical outcome. ULBD could be considered to be useful and effective technique for lumbar spinal stenosis.