Effective postoperative pain management is crucial for the rehabilitation of the surgical patient. No ‘gold standard’ exists after total hip arthroplasty (THA) and combinations of various nonopioid medications are employed with virtually no evidence for further analgesic efficacy as compared to monotherapy. The analgesic effects and safety of paracetamol and ibuprofen alone and in combination in different dosages after THA have been explored in this study.

A placebo-controlled, parallel four-group, multicentre trial with centralised computer-generated allocation sequence and allocation concealment along with varying block size and stratification by site is called PANSAID. Blinding of assessor, investigator, caregivers, patients and statisticians. The patients are stratified into four groups: (A) paracetamol 1 g × 4 and ibuprofen 400 mg × 4, (B) paracetamol 1 g × 4 and placebo, (C) placebo and ibuprofen 400 mg × 4 and (D) paracetamol 0.5 g × 4 and ibuprofen 200 mg. Within 90 days after surgery, 24-h consumption of morphine and number of patients with one or more serious adverse events were depicted as the two co-primary outcomes. Pain scores during mobilisation and at rest at 6 and 24 h postoperatively, and number of patients with one or more adverse events within 24 h postoperatively were depicted as the secondary outcomes. As per the inclusion criteria, the patients scheduled for unilateral, primary THA; age above 18 years; ASA status 1–3; BMI >18 and <40 kg/m2; women must not be pregnant; and provision of informed consent were considered. The exclusion criteria comprised of patients who cannot cooperate with the trial; participation in another trial; patients who cannot understand/speak Danish; daily use of strong opioids; allergy against trial medication; contraindications against ibuprofen; alcohol and/or drug abuse. Five hundred and fifty-six patients are required to reveal a difference of 10 mg morphine i.v. the first 24 h postoperatively with a standard deviation of 20 mg and a family wise type 1 error rate of 0.025 (two-sided) and a type 2 error rate of 0.10 for the six possible comparisons of the four intervention groups.

This trial is expected to cease in September 2017. This trial was commenced in December 2015. The data estimation will be from September 2017 to October 2017 and manuscript submission ultimo 2017.