RecruitingCombination productTotal Intravenous Anesthesia vs Spinal Anesthesia in Patients Undergoing Unilateral Primary Total Knee ArthroplastyThe purpose of this study is to compare same-day discharge rates and recovery outcomes across an adult patient population undergoing elective Total Knee Arthroplasty (TKA), and randomized to receive either spinal block anesthesia or Total IntraVenous Anesthesia (TIVA). Primary Aim: assess same-day discharge rates between study arms (TIVA vs spinal). Secondary Aim: Postoperative comparison of recovery during PostOperative Anesthesia Care Unit (PACU) admission, diagnostic assessment scores; outcomes related to cognition, hemodynamic stability, pain, nausea and vomiting; analysis of IntraOperative electroencephalogram (EEG) monitoring metrics, e.g., total suppression time, average Bi-spectral Index monitor (BIS) value, Spectral Edge Frequency (SEF); ability for Physical Therapy (PT) evaluation prior to discharge; longterm-followup (LTFU), hospital readmission, return to surgery, etc.; adverse event (AE) monitoring.