Interbody vs Instrumented Posterolateral Fusion Following Decompression for Lumbar Spinal Stenosis With Degenerative Spondylolisthesis

Degenerative spondylolisthesis describes the slip of one spinal segment relative to the adjacent segment. It is usually associated with spinal stenosis (which limits one's ability to walk and stand) and is the most common indication for surgery in adults over age 65 years. A variety of surgical techniques are available; the most common are the Posterolateral Instrumented Fusion (PLF), and Interbody Fusion (IF) including Posterolateral Interbody Fusion (PLIF), and Transforaminal Interbody fusion (TLIF). IF uses a cage that is placed within the cleaned out disc space between the vertebral bodies being fused. Although this approach achieves a good fusion rate and deformity correction it is associated with a higher surgical cost and potential intra-operative complication rate. What is more, no consensus exists as to whether IF provides better patient rated functional outcome and quality of life. If the advantages of IF do not translate into superior patient rated outcomes, then the risk-benefit ratio would be tipped in favor of PLF. The purpose of this study is to determine if IF is equivalent to PLF for the treatment of degenerative spondylolisthesis. The investigators will conduct a prospective randomized control trial comparing these two procedures. Our primary outcome measure will be the Oswestry Disability Index, which evaluates spinal pain and function.