Chronic Low Back and Leg Pain

The goal of this clinical trial is to learn if there are differences in the effectiveness of decompression surgery alone versus decompression combined with extended fusion in patients with a previous lumbar spinal fusion who now present with symptoms of lumbar adjacent segment stenosis (LASS). The main questions it aims to answer are: * Does decompression alone differ from decompression combined with extended fusion with regard to clinical outcomes two years after surgery? * Are there any clinical or radiological characteristics that can predict better or worse outcomes two years after surgery? * Are there any differences between the treatment groups in terms of health economics? Researchers will compare decompression surgery alone versus decompression combined with extended fusion to see if there are any differences in treatment effect. Participants will: * Be randomized to one of the two surgical procedures * Visit the clinic four times postoperatively (at three months, 1, 2 and 5 years) for checkups and tests * Respond to questionnaires before surgery, and three months, 1, 2 and 5 years postoperatively

Chronic low back pain is a common and disabling condition that affects millions of people in the United States. Many people with chronic low back pain do not get enough relief from current treatments. Cannabis may help reduce pain, but researchers do not fully understand how it affects the brain in people with chronic pain. The purpose of this study is to examine how inhaled cannabis changes brain activity and reduces pain in people with chronic low back pain. Results from this study may help researchers better understand how cannabis works for pain and support the development of improved pain treatments.