 Patients and methods 20 otherwise healthy patients 10 males and 10 females age 50-75 years undergoing elective total knee arthroplasty in Department of Orthopaedic Surgery, Hvidovre Hospital. All patients undergo standard anesthesia and analgesic treatment in a fast-track set-up with discharge not earlier than 48-hours postoperatively.Husted et al 2011 Exclusion criteria are 