Transdermal fentanyl patch for postoperative analgesia in total knee arthroplasty: a randomized double-blind controlled trial

Purpose: To assess the efficacy of a transdermal fentanyl patch (TFP) (50 mu g/hour) applied 10-12 hours before surgery versus placebo for postoperative pain control of total knee arthroplasty (TKA). Materials and methods: We enrolled 40 patients undergoing elective TKA under spinal anesthesia using isobaric or hyperbaric bupivacaine. Subjects were randomized to receive a TFP (Duragesic (R) 50 mu g/hour) or placebo patch applied with a self-adhesive to the anterior chest wall 10-12 hours before spinal anesthesia. Every patient was given patient-controlled morphine for postoperative pain control. Patients were evaluated every 4 hours until 48 hours. Results: Morphine consumption at 24 and 48 hours in the TFP group versus the placebo group was 15.40 +/- 12.65 and 24.90 +/- 20.11 mg versus 33.60 +/- 19.06 and 57.80 +/- 12.65 mg (P <= 0.001). Numeric rating scale scores at rest and during movement over 48 hours were lower in the TFP group. Ambulation and nausea/vomiting scores were statistically greater, but not clinically significant in the TFP group. Sedation scores were low and not statistically significantly different between groups. There was no severe respiratory depression. Conclusion: TFP (50 mu g/hour) applied 10-12 hours before surgery can effectively and safely decrease morphine consumption and pain scores during the first 48 hours after TKA surgery.