The patients after total knee arthroplasty (TKA) commonly experience postoperative pain. This randomised clinical trial with 134 patients based on the effectiveness of tapentadol ER and oxycodone CR as an add-on to multimodal analgesia which portrayed tapentadol to be no good than oxycodone concerning pain relief.

This study aimed to compare the efficacy of tapentadol extended-release (ER) 50 mg and oxycodone controlled-release (CR), both given twice daily and placebo; plus a multimodal analgesic therapy both in-hospital and at home the first 7 days following TKA.

The study was randomized and blinded for researchers, staff, outcome assessors and patients. Pain intensity on mobilization, pain at rest, worst pain in the last 24 hours, and adverse effects assessed on 0-10 numeric rate scales was evaluated at follow-up.

Overall, 134 patients were divided into 3 groups. Primary outcome pain on mobilization the 7 first postoperative days described as mean pain Area Under the Curve (AUC) was 528.1 for placebo, 427.2 for tapentadol ER and 507.9 for oxycodone CR. No significant differences between therapy groups for the secondary outcomes were found except, constipation being less frequent in the tapentadol ER group. 

The use of tapentadol ER as an add-on to multimodal analgesia did not provide significant pain relief than oxycodone CR or placebo.