Introduction:This study evaluated the effect of bupivacaine versus mepivacaine spinal anesthesia and preoperative adductor canal block (ACB) on recovery, length of stay, pain, and complications of same-day discharge total knee arthroplasty (TKA) at a free-standing ambulatory surgery center.Methods:We performed a retrospective review of patients who underwent TKA between March 2018 and September 2019. The patients were grouped based on the neuraxial anesthetic regimen: bupivacaine with ACB, bupivacaine without ACB, and mepivacaine without ACB. Preoperative ACBs were discontinued in December 2018, and use of mepivacaine spinal anesthesia was initiated in March 2019. Length of stay in the postanesthesia care unit (PACU), time to controlled void and ambulation, postoperative pain, morphine milligram equivalents (MME), and transient neurologic symptoms were compared.Results:Ninety consecutive patients who underwent TKA were identified. Fifty patients received bupivacaine with ACB, 20 received bupivacaine without ACB, and 20 received mepivacaine without ACB. Mepivacaine spinal anesthesia led to a 93-minute shorter PACU stay (P < 0.001), 115-minute quicker time to void (P < 0.001), 60-minute earlier ambulation (P = 0.024), and 109-minute shorter total facility time (P = 0.003) but increased total MME (P = 0.049) despite nonsignificant difference in pain at discharge (P = 0.908) compared with bupivacaine. Patients receiving bupivacaine with and without ACB had a nonsignificant difference in pain scores at discharge, time to ambulation, and time to discharge (P ≥ 0.1). No transient neurologic symptoms or overnight stays were observed.Discussion:Mepivacaine spinal anesthesia for TKA safely facilitated more rapid same-day discharge through decreased times to controlled void and ambulation but with a slight increase in MME requirements. Discontinuing preoperative ACBs did not negatively affect PACU outcomes.