Fusion of Spine, Lumbar Region

The purpose of this study is to determine if the method for injecting local anesthesia affects patients' pain and opioid usage after surgery. The investigators will compare subcutaneous anesthesia, injections of anesthesia under the skin, to a method called erector spinae plane block (ESPB). An ESPB injection involves placing local anesthesia along the muscles and bones in the back, using a special type of x-ray called fluoroscopy for guidance. The Investigators will use patient reported outcomes (PROs) and track subjects' opioid usage to find out if there is a difference between ESPB and subcutaneous anesthesia. The investigators hypothesize that patients who get ESPB injections will use less opioids and report less pain after lumbar fusion surgery compared to patients who receive subcutaneous anesthesia injections.