The purpose of this study is to study the efficacy of pre-emptive etoricoxib in reducing post-operative pain and improving function outcome after a total knee arthroplasty.

Total knee arthroplasty (TKA) is one of the most commonly performed orthopaedic surgeries worldwide and has proven to be a success in the treatment of end-stage osteoarthritic knees. TKA is associated with significant postoperative pain which may delay the patient's functional recovery and necessitate an increased use of opioid analgesias, which are themselves associated with significant adverse effects such as nausea and vomiting. The selective cycloxygenase (COX)-2 inhibitor rofecoxib was previously shown in a clinical trial in a paper by Buvanendran et al to reduce postoperative opioid requirement and improve clinical outcomes. Feng et al studied the use of a single dose of rofecoxib pre-operatively and its effect on inflammatory markers and postoperative pain. Rofecoxib has, however, been withdrawn from the market due to its association with cardiovascular side effects. Our current clinical practice in post-operative pain management constitutes post-operative etoricoxib but we hypothesize that pre-emptively administering etoricoxib pre-operatively would give an even greater benefit in terms of post-operative opioid usage, pain scores, and functional recovery in the first 2-3 days. To date, there has been no study investigating etoricoxib as a pre-emptive medication in patients undergoing total knee arthroplasty. We aim to conduct a study to test the efficacy of pre-emptive etoricoxib in reducing postoperative pain, opioid requirement and improving the rate of functional recovery.

Inclusion Criteria:

• Patients between the ages of 50 and 80 who are listed for single-knee TKA at Singapore General Hospital by one of 4 adult reconstructive surgeons for the treatment of osteoarthritis will be recruited upon the patient giving written informed consent.

Exclusion Criteria:

• - Younger than 50, older than 80
• Known allergy to etoricoxib or other cycloxygenase-2 inhibitors, aspirin or any Non-steroidal Anti-inflammatory Drugs (NSAIDs)
• American Society of Anaesthesiologists (ASA) grade IV
• Renal insufficiency (Creatinine > 110)
• Known coagulation or hepatic disorder
• Inflammatory arthritis
• Inflammatory bowel disease
• Concurrent conditions which would affect interpretation of pain eg spinal stenosis, lumbar nerve root impingement
• Depression or usage of opioids, sedatives or hypnotics preoperatively
• Special classes of subjects including those pregnant, cognitively impaired, prisoners or institutionalized patients
• Patients with clinically significant abnormalities of laboratory safety tests at baseline, or a history of significant clinical or laboratory abnormality that in the opinion of the investigator would contraindicate the use of etoricoxib
• Patients with unstable hypertension, uncontrolled diabetes mellitus, New York Heart Association (NYHA) class II-IV congestive heart failure, ischaemic heart disease, cerebrovascular disease or peripheral vascular disease (including patients who have recently undergone coronary artery bypass graft of angioplasty)
• Patients with active gastric ulceration or gastrointestinal bleeding
• Patients with a history of any illness that in the opinion of the investigator may confound the results of the study or pose additional risks to the patient
• Occurrence of any surgical complication would exclude the patient from analysis