Effect of Preoperative Intravenous Methocarbamol and Intravenous Acetaminophen on Opioid Use After Primary Total Hip and Knee Replacement

Between 2010 and 2011, a perioperative pain protocol for primary total hip and knee replacement at one Florida medical center replaced preoperative oral analgesics with intravenous methocarbamol and intravenous acetaminophen. This is a retrospective cohort study of 300 patients, with 150 patients using the new pain protocol and 150 patients using a 2008 pain protocol that did not include these medications. The 2 cohorts were similar in patient gender, age, and body mass index. Opioid consumption was evaluated for a period of 48 hours after incision and was divided into 3 separate time intervals, as well as total 48-hour consumption. Mean opiate use decreased significantly from 2008 to 2011 in all time intervals and total consumption (7.5±3.4 mg to 6.1±3.0 mg; P <.01). Subgroup analysis suggested that changes to the hip protocol were responsible for decreased opioid use in the operating room and the postanesthesia care unit, and changes to the knee protocol were responsible for decreased opioid use on the hospital floor and total consumption. The difference between the 2 protocol groups was not due to differences in individual surgeon practice patterns. Physical therapy progress of knee flexion, average walking distance, and maximum walking distance were significantly improved. Hospital discharge was shorter in the 2011 group (4.0±1.1 days in 2008 group and 3.6±1.0 days in 2011 group). This study shows significant improvement in patient care from 2008 to 2011 that is at least partially due to the change to the use of preoperative intravenous methocarbamol and intravenous acetaminophen.