Efficacy of Adding Acetaminophen to Preemptive Multimodal Analgesia in Total Knee Arthroplasty: A Double‐blinded Randomized Study

Preemptive multimodal analgesia is a frequently utilized method for controlling pain after total knee arthroplasty (TKA). So far, no studies have specifically examined the efficacy of adding acetaminophen to preemptive multimodal analgesia in TKA. The current work aimed to assess the efficacy of adding acetaminophen to preemptive multimodal analgesia for clinical pain management after TKA.This was a double-blinded randomized study including 80 cases randomized to the acetaminophen and control groups, respectively. The acetaminophen group was administered celecoxib at 400 mg, pregabalin at 150 mg, and acetaminophen at 300 mg 2 h before TKA. Control patients were administered celecoxib, pregabalin, and placebo. The primary outcome was postsurgical use of morphine hydrochloride for rescue analgesia. Secondary outcomes included the time to the initial rescue analgesia, postsurgical pain as determined by a visual analogue scale (VAS), functional recovery as reflected by the range of knee motion and ambulation distance, hospitalization duration, and complication rates. Continuous data with normal and skewed distributions were compared by the Student's t test and the Mann-Whitney U test, respectively. Categorical variables were compared by the Pearson's chi-squared test.The control and acetaminophen groups were comparable in postoperative 0-24 h morphine consumption (11.3 ± 6.5 mg vs 12.3 ± 7.7 mg, P = 0.445) and total morphine consumption (17.3 ± 10.1 mg vs 19.3 ± 9.4 mg, P = 0.242). Additionally, time to the initial rescue analgesia, postoperative VAS score at any time point, postoperative functional recovery of the knee, and hospitalization duration were similar in both groups. Both groups also had similar occurrence rates of postoperative complications.In this study, adding acetaminophen to preoperative preemptive multimodal analgesia did not decrease postoperative morphine use or ameliorate pain relief. The efficacy of adding acetaminophen to preemptive multimodal analgesia in TKA need to be further explored in future studies.