Study population
Included were patients undergoing elective cruciate ligament surgery. Every patient received a standard of care total intravenous anesthesia consisting of an induction with propofol, remifentanil and, if relaxation required, rocuronium followed by a maintenance with remifentanil (0.15–0.25 μg⋅kgSample size calculations: from chart reviews, we derived a range of 4–6 mg hydromorphone usage within 24 h for patients with no prophylactic diclofenac intraoperatively, diclofenac, and diclofenac plus orphenadrine administration intraoperatively with a standard deviation of 2 mg. With an a‑error of 0.05 and a power (1-b) of 0.85, and a 1:1:1 allocation ratio 66 patients overall were calculated and 10% were added to compensate for study dropouts for ANOVA analysis, leading to 72 patients.