High-Dose Steroid for Knee Arthroplasty

The purpose of the Study is to test a higher dose of steroids(Dexamethasone) given just prior to surgery in the setting of Fast-Track Kneesurgery with Arthroplasty and the effect on postoperative pain and postoperative inflammation.

This study compares a new High-Dose dosage of steroids in the treatment of postoperative pain after Knee Arthroplasty in a Fast-Track setting. 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 on 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 doubleblinded. 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. Also a series of blood tests determining the glucose-metabolism after the steroid-admission.

Postoperative Pain, Postoperative Nausea and Vomiting, Knee Osteoarthritis, Perioperative/Postoperative Complications, Surgery

All intervention drugs will be blinded by a nurse who is not a participant in the study or in the treatment of the patient in any way. The Patient, the administrator of the drug(nurse or doctor), the assessor, the investigator and the care team will all be blinded.

An intravenous bolus dose of Dexamethasone 1 mg/kg bodyweight administered preoperatively before surgery.

An intravenous bolus dose of Dexamethasone 0,3 mg/kg bodyweight administered preoperatively before surgery.

The amount of patients with moderate postoperative pain in a 5 meter walk test 24 hours postoperatively after total knee-arthroplasty. Pain is monitored by the Visual Analog Scale(VAS) 0-100 mm, where 0 is no pain and 100 mm is the worst pain. Moderate pain is considered a VAS >30 mm.

The inflammatory response is monitored by the blood-sample c-reactive protein(CRP) and analyzed to se the possible attenuation of the response because of dexamethasone.

Pain summarized over the first 7 days after surgery, assessed by a summation of the Visual Analog Scale(VAS)-scores in the first 7 days as noted in the pain diary filed in by the participants.

Why still in hospital, an audit into the reasons the patient has not yet been discharged from the ward.

An investigation into reason of why our patients remain in the hospital in the days after total Knee Arthroplasty in our Fast-Track center. This is investigated through a questionnaire previously used in a similar investigation in our center. The questionnaire is filled in by our project nurse. the questionnaire is a checkmark schedule with predetermined reasons to stay in hospital like low bloodpressure, sedation, dizzyness, lack of physiotherapy and medical and surgical complications. The outcome assesment will be descriptive.

Inclusion Criteria: Age between 40 and 90. Booked for unilateral knee-arthroplasty. Is able to take part in the investigation(selfreported pain and nausea/vomiting) Understands Danish or English, or has a translator available. Signed written consent. Exclusion Criteria: Insulin-dependent diabetes melitus. Ongoing treatment with systemic glucocorticoids or immunosuppressing treatment(apart from inhaled glucocorticoids). Pregnancy/Breastfeeding Allergies for the investigational drug. Daily use of opioids. A pain catastrophizing scale(PCS) score of >20. A history of schizophrenia or bipolar diseases, or patients with permanent use of antipsychotic medication.