The Effect of Preoperative Opioid Dosage on Postoperative Outcomes in Patients Undergoing Knee Surgery

摘要

Background: Opioid prescription before knee replacement surgery is associated with longerhospital stays, more postsurgical pain, and a higher rate of complications. Despite the growingevidence against opioids, they remain popular preoperative pain management prescriptions.Objectives: The purpose of this study was to examine the effects of dosage of preoperativeopioid use on orthopedic knee surgery pain control and postoperative outcomes andcomplications.Study Design: Observational, retrospective evaluation.Setting: University of Wisconsin Madison hospitals.Methods: The patients underwent orthopedic knee surgery between May 1, 2014 andApril 30, 2015. We randomly selected 197 patients and divided them into 2 groups that hadpreoperative opioid dosages of either low dose ≤ 120 mEq morphine (MME) or high dose>120 MME. Of 197 patients, 100 were in the low dose morphine group, whereas 97 werehigh dose. The cutoff at 120 MME was calculated to be the median dosage across all patients.The primary outcomes were compared, differences in postoperative pain control, and range ofmotion (ROM). Secondary outcomes included anesthetic complications, length of hospital stay,postoperative opioid dose, and postoperative complications.Results: There were no statistically significant differences between the groups with regardto postoperative pain control, ROM, and immediate postoperative complications. Both groupsshowed similar length of hospitalization (2.199 to 2.304 days; P = 0.374), rate of postoperativeinfection, and joint intervention. The high dose group was more likely to have postoperativehemarthrosis and emergency department (ED) visits. However, the low dose group was morelikely to have hypertension concurrently.Limitations: Because the study length was restricted to one year, the lack of data on longerterm prognosis may limit extrapolation of data. Subjectivity of pain is difficult to measure andcompare objectively. This study was not randomized prospectively, which may bias certainresults due to unobserved differences.Conclusions: Preoperative opioid dose did not affect postoperative pain control or ROM inpatients who received knee surgeries. Higher preoperative opioid doses were associated withmore hemarthrosis and ED visits. Further exploration into quality of life indices and surgicalcomplications such as need for revision may be a fruitful avenue.