Evolution of an Opioid Sparse Pain Management Program for Total Knee Arthroplasty With the Addition of Intravenous Acetaminophen

Perioperative pain management for patients undergoing total knee arthroplasty (TKA) improves patient outcomes and facilitates recovery. In this study, we compared the effects of preoperative oral acetaminophen vs intravenous (IV) acetaminophen administered once intraoperatively and once postoperatively.

Two standardized, multimodal analgesia protocols were compared in patients undergoing primary, unilateral TKA. The oral acetaminophen cohort (OA) received doses of oral acetaminophen preoperatively and an as-needed basis postoperatively (n = 698). The IV acetaminophen cohort (IA) received 2 doses of IV acetaminophen, one intraoperative and one 6 hours postoperatively, with no oral acetaminophen given (n = 318). No other variables were significantly changed during the study period.

The IV acetaminophen group demonstrated less narcotic usage on postoperative day 0 (OA: 13.3 mme [morphine mg equivalents], IA: 6.2 mme, P < .001) and overall usage (OA: 66.1 mme, IA: 48.5 mme, P < .001). Pain scores were statistically and clinically significantly decreased in the immediate postoperative (the first 8 hours) for the IA group (OA: patient-reported pain scores of 4.0; IA: patient-reported pain scores of 2.0, P < .001). Both groups progressed and completed their physical therapy similarly for each postoperative day. Length of stay and percent discharge home were slightly improved in the IA group as well, however did not reach statistical difference.

An iterative approach to multimodal pain management after TKA led to improvements in narcotic usage, pain scores, and several quality measures. IV acetaminophen is an integral and effective part of our opioid-sparing multimodal pain regimen in TKA.