Inclusion Criteria:  Patients undergoing primary unilateral total hip arthroplasty (THA), total knee arthroplasty (TKA) or unicompartmental knee arthroplasty (UKA) Patients > 18 Patients that understand and speak Danish Patients that have provided written informed consent  Exclusion Criteria:  Alcohol or substance abuse Habitual use of opioids Habitual use of anxiolytic, antidepressant and/or antipsychotic drugs History of previous orthostatic intolerance or hypotension Cognitive dysfunction Glomerular filtration rate (GFR) < 30 ml/min Cardiac arrhythmia