2.3. Randomization and interventions
pain
Patients were randomly assigned to 1 of 3 study groups, receiving either oxycodone CR 10 mg × 2, tapentadol ER 50 mg × 2, or placebo as their study drug in addition to multimodal basal pain medications. Details of the randomization method and intervention have been described previously.Naproxen, acetaminophen, and the study drug were given as scheduled drugs for 7 days. Thereafter, the patients were advised to use naproxen 500 mg and esomeprazole 20 mg twice daily, acetaminophen 1000 mg up to 4 times a day, and oxycodone immediate-release (IR) 5 mg if needed. The study was finalized with a telephone interview 14 days postoperatively. All patients followed a standardized fast-track patient course as previously described in the literature.When the patients arrived at the recovery unit, an activity monitor (activPAL™, PAL Technologies Ltd., Glasgow, UK) was placed on the patient’s non-operated thigh before mobilization. The patients were mobilized using a pulpit walker as soon as the motor function/control of the lower extremities was adequate. All patients received daily individual physical therapy during their hospital stay that included instructions for stretching, getting in/out of bed, walking with crutches on plain surfaces as well as ascending/descending stairs. A daily group session led by a physiotherapist was optional.From the day of surgery, the patients received study medication twice daily. The multimodal basic pain medication consisted of naproxen 500 mg and esomeprazole 20 mg 1 tablet twice daily and acetaminophen 1000 mg 4 times daily for 7 days. Study drugs were given at the same time of the day during hospitalization, which corresponded to the nurses’ medication rounds. After discharge, pain medication times were at the patient’s own preference. The instructions were identical for all patients with morning, noon, afternoon, and evening as “medication times.” No instructions for pain medication by clock times were given. For rescue analgesia, patients had the opportunity to take 5 mg oral oxycodone IR on demand. The use of all scheduled analgesics, study medication, and daily doses of rescue oxycodone were recorded. The use of all scheduled analgesics, study medication, the daily dose of rescue oxycodone as well as registration of pain level and side effects were recorded by the patients using a tablet/iPad with an application developed for the study.