Duloxetine Impact on Postoperative Pain Control and Outcomes

1. Evaluate differences between patients taking Duloxetine or placebo following lateral lumbar interbody fusion for postoperative narcotic consumption. 2. Evaluate differences between patients taking Duloxetine or placebo following lateral lumbar interbody fusion for postoperative pain, function, and quality of life. 3. Evaluate the correlation between preoperative screening tests (measuring pain centralization, anxiety, depression, and overall function) and patients\' response to treatment (reduction in pain, anxiety, or depression and improvement in function).