This study compares two regional anesthesia techniques used for pain control after lumbar spine surgery: the classic thoracolumbar interfascial plane (TLIP) block and the quadratus lumborum-iliac plane (QIP) block. Patients between 18 and 65 years of age who undergo elective lumbar discectomy (up to two spinal levels) will be observed based on which block their treating anesthesiologist chooses to use as part of routine clinical practice. No randomization or additional intervention beyond standard care will be performed. Researchers will record the total amount of opioid pain medication used in the first 24 hours after surgery, the time until the first request for pain medication, pain scores at several time points after surgery (0, 1, 2, 4, 8, 12, and 24 hours), and any side effects (such as nausea, vomiting, or sedation) or complications related to the block. The aim is to compare the effectiveness and safety of these two techniques in reducing pain and opioid use after lumbar spine surgery.