Given the potential for non-steroidal anti inflammatory drugs (NSAIDs) and acetaminophen to decrease opioid requirements following spine surgery, the investigators propose a prospective, randomized, double-blinded clinical trial comparing the efficacy of intravenous (IV) acetaminophen (Group A) or IV ketorolac (Group K) versus placebo (Group P). The impact of treatment on perioperative opioid use, opioid-related complications, functional outcomes and rates of pseudarthrosis following 1 or 2 level lumbar fusion surgery will be measured in each group. The specific aims of this study are as follows: