High-Dose Steroid for Knee Arthroplasty Patients Expected to Have Postoperative Pain

This study compares a new High-Dose dosage of steroids in the treatment of postoperative pain after Knee Arthroplasty in a Fast-Track setting in a group of expected High Pain Responders. The investigators compare the already used dose(medium dose) with a new high dose(HD) steroid given as an intravenous bolus after the spinal anaesthesia has been given, but before the surgery starts. The hypothesis is that by attenuating the inflammatory response to the surgery itself by the steroid Dexamethasone, the investigators expect a reduction in postoperative pain upon ambulation 24 hours after unilateral Knee Arthroplasty. Patients referred to Unilateral Total KneeArthroplasty because of knee-osteoarthritis at Hvidovre Hospital, Capital Region of Denmark or Vejle Hospital, South Region of Denmark are screened and offered inclusion in the study. The two groups will be randomized and double blinded. One group will be treated, as the current guideline in the investigator's Orthopedic fast-track Arthroplasty center, with the medium dose of steroid (0,3 mg dexamethasone/kg bodyweight). The other group wil be treated with a high dose of steroid (1,0 mg dexamethasone/kg bodyweight). The patients will be monitored the first 7 days after surgery, during the admission to the hospital, and by a Pain-diary in the patients own home. Blood tests will be taken preoperatively and postoperatively to determine the effect of the highdose steroid on the inflammatory response.