P134. Midterm clinical and radiological outcomes of lumbar spinal stenosis with concurrent scoliosis and/or spondylolisthesis after minimally invasive lumbar decompression surgery: Minimum 5-year follow-up

BACKGROUND CONTEXT Several studies recently have been published about the sagittal spinal alignment of lumbar spinal canal stenosis (LSS) after decompression surgery, however, little is known about these variables of LSS with concurrent degenerative spondylolisthesis (DS) and/or lumbar scoliosis (DLS). With aging of the population, spine surgeons are currently more and more confronted with a wide variety of degenerative changes of the lumbar spine. PURPOSE The purpose of this study was to investigate whether the radiological and clinical outcomes differ depend on the concomitance after minimally invasive lumbar decompression surgery. STUDY DESIGN/SETTING Retrospective analysis of prospectively collected data. PATIENT SAMPLE A total of 244 patients underwent bilateral decompression via unilateral approach using microscope or microendscope at our instituted between 2008 and 2013, and were followed up for more than 5 years postoperatively. A total of 169 patients were included in the final analysis (88 women, 81 men; mean age at surgery, 69.5±9.2years). The patients were divided into three groups: LSS group (without DS and DLS; n=91), DS group (n=59) and DLS group (n=19) OUTCOME MEASURES Clinical outcomes were evaluated with the Japanese Orthopaedic Association (JOA) scoring system (29 possible points) and visual analog scale (VAS) score for low back pain (LBP), leg pain, leg numbness and achievement of minimal clinically important difference (MCID) of VAS for low back pain (LBP) or leg pain (LP). Furthermore all spinopelvic parameters such as 1) cervical lordosis (CL): C2–7 angle (positive means lordosis); 2) cervicothoracic kyphosis (CTK): C7–T5 angle (positive means kyphosis); 3) thoracic kyphosis (TK): T5–12 angle (positive means kyphosis); 4) lumbar lordosis: T12–S1 angle (positive means lordosis); 5) C7–S1 sagittal vertical axis (SVA): distance between C-7 plumb line and posterosuperior sacrum; 6) pelvic parameters: sacral slope (SS), pelvic tilt (PT), pelvic incidence (PI) and PI – LL were evaluated. METHODS All patients underwent bilateral decompression via a unilateral approach to decompress the central and bilateral lateral recess using a microscope or the METRx Microendoscopic Discectomy System (Medtronic Sofamor Danek, Warsaw, IN, USA). Outcomes were quantified comparatively among Simple LSS group vs DS group (with anterior slip of more than 3mm) and DLS group (with ≥ 20° coronal Cobb angle) using low back pain (LBP) /leg pain/leg numbness visual analog scale (VAS) scores, the JOA scores and variables about sagittal plane alignment before surgery, 2 years and 5 years of follow-up. RESULTS In patients coexisting DS, the clinical outcomes at 2year and 5-year after surgery were similar with that of LSS except for VAS leg numbness. In patients coexisting DLS, the VAS leg pain at 2-year after surgery was significantly higher (34.5 vs 14.5, P=0.001) and the achievement rate of the minimal clinically important difference in VAS LBP and leg pain was significantly lower than LSS group (26.3% vs 52.7%; P=0.036, 42.1% vs 72.5%; P=0.01). The reoperation rate of DS group was significantly lower than that of LSS group (3.4% vs16.5%; P=0.01), but the DLS group was comparable to the LSS group (15.8% vs 16.5%; P=0.941). Lumbar lordosis (LL), pelvic tilt and pelvic incidence-LL were significantly improved and maintained for 5 years after surgery, however, sagittal vertical axis improved at 2-year follow-up, but no significantly difference was observed at 5-year follow-up in both the DS and the DLS group. CONCLUSIONS Among patients with DS and DLS, the clinical effectiveness and radiological changes after minimally lumbar decompression surgery alone was noninferior to that of LSS without deformity. The less invasive procedure should be considered for most LSS patients. FDA DEVICE/DRUG STATUS Unavailable from authors at time of publication.