 This is a prospective, single-blinded, placebo controlled single center trial. One hundred subjects 50 in each arm will be enrolled. Subjects undergoing multilevel spinal fusion will be screened and have the study introduced and discussed with them during the preadmission visit. Subjects may also contact study personnel or be contacted by study personnel before admission. Upon admission on the day of surgery, patients will be re-screened, recruited, have informed consent obtained. After consent is achieved in the pre-admission clinic prior to surgery, patients will be asked to fill out Becks depression inventory BDI, post-operative quality of recovery scoreQoR-15 form, visual analog scale VAS for pain and short form McGill pain questionnaire to establish baseline scores. These forms can be completed at pre-admission testing, at home or on the day of surgery. The three forms will be on postoperative days POD 1, 2 and 3; only the VAS will be given in the Post-Anesthesia Care Unit PACU. Eligible subjects will be assigned to either the ketamine or placebo group based on a computer generated randomization randomization.com. Baseline demographic data as well as medical history and medication list will be recorded. 