221. Change in sagittal alignment after decompression alone in patients with lumbar spinal stenosis: a prospective cohort study

Abstract

BACKGROUND CONTEXT Patients with lumbar spinal stenosis present with low back pain, numbness and pain in the legs and gait difficulties due to neurogenic claudication. Patients often walk in a stooped posture to increase the spinal canal diameter by stretching out the ligamentum flavum. This stooped posture leads to a positive sagittal balance. After decompressive surgery, patients may walk in a less stooped manner, improving their sagittal balance, which may lead to less back pain and improved patient reported outcomes. PURPOSE To determine if sagittal balance will improve in patients with spinal stenosis after decompression alone. STUDY DESIGN/SETTING Prospective longitudinal cohort study. PATIENT SAMPLE Patients with lumbar spinal stenosis who underwent decompression alone. OUTCOME MEASURES Oswestry Disability Index (ODI), visual analogue scale (VAS)- leg and back pain. METHODS This study compares preoperative and 6-month postoperative full-length 36” standing lateral and posterior-anterior x-rays and 1-year Oswestry Disability Index (ODI), visual analogue scale (VAS)- leg and back pain, in patients undergoing decompression alone without fusion for central or combined central and lateral stenosis, in patients 60 years and older from March 2016 until September 2017. The following radiographic parameters were measured coronal cobb angle (COBB), pelvic incidence (PI), sagittal vertical axis (SVA), lumbar lordosis (LL), pelvic tilt (PT), pelvic incidence-lumbar lordosis ratio (PI-LL) and sacral slope (SS). RESULTS Forty-five patients (24 males and 21 females) were included. Patients had symptoms for more than 3 months at the time of surgery. Most patients were operated with a bilateral laminectomy over two levels. Sagittal balance showed a statistically significant change in SVA from 65.0mm to 48.6mm (p=0.009) and PI-LL mismatch 7.80 to 4.24 (p= 0.005). A small to moderate association was found between SVA and ODI both preoperatively (r=0.54, p= 0.001) and postoperatively (r=0.51, p= 0.001) and preoperative VAS-leg/back pain (r=0.60, p=0.001)/(r=0.42,p=0.009). CONCLUSIONS There is a statistically significant improvement in sagittal balance in patients undergoing decompression alone for lumbar spinal stenosis. Associations between the SVA and ODI and VAS-leg/back pain indicate that improvements in sagittal balance contribute to improvements in patient reported outcomes. FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs.