Serious adverse events within 90 days after surgery. Total need of i.v. morphine the first 24 hours postoperatively; total need of oral morphine the following 24-48 hours. Visual analogue scale (VAS) pain scores at rest and with active 45 degrees flexion of the knee at 6, 24 and 48 hours postoperatively, and both highest and average pain score in the periods 0-24 h and 24-48 hours postoperatively. Timed up and go test at 24 and 48 hours postoperatively, including maximum pain during the test. Adverse event from intervention start to 48 hours as well as levels of nausea, vomiting, dizziness, and sedation at 6, 24, and 48 hours. Consumption of antiemetic in the periods 0-24 and 24-48 hours postoperatively. Quality of sleep and level of fatigue at 24 hours and 48 hours. Questionnaire on pain, sleep, satisfaction and use of medication for POD 3-7. 90-day follow-up with EQ-5D-5L and Oxford-Knee-Score at 90 days postoperatively and the need for medical attention and/or intervention including need for antibiotics and/or re-operation.