Despite the development of new pain medications, the prevalence of persistent postoperative pain (for more than three to six months) remains alarmingly high. Chronic pain and reduced function after surgery are of great concern since they have a significant impact on a patient's quality of life and are costly to society in terms of longer hospital stays and lost work days. An important risk factor for chronic pain and reduced function after surgery is the amount of pain patients experience immediately after surgery which is highly influenced by the amount of pain patients have preoperatively. For many patients, longstanding pain prior to surgery is common and thus can compromise the outcome of the procedure. Therefore, the aim of this study is to reduce the amount of pain patients have before they undergo surgery by administering a novel pain-relieving regimen in the weeks before surgery. Crucially, this treatment will be continued for three weeks after surgery to reduce pain that arises from the surgical trauma. The novel regimen will include a non-steroidal anti-inflammatory (celecoxib) and the alpha2 delta ligand, pregabalin. This drug combination will provide the best opportunity to target several key sites in the pain pathway. This regimen will be tested in patients with pain related to osteoarthritis and who are undergoing orthopedic (hip) surgery because chronic preoperative pain is common in these patients and is the main reason for undergoing surgery. The goal of this research proposal is to adequately manage pain before and after surgery in order to improve function weeks after surgery. If controlling pain in this way does lead to improved long term postoperative function the findings from this study may lead to the development of a standardized regimen. This is highly relevant not only for orthopedic procedures but following other common surgical procedures which would be of great benefit to patients and the entire healthcare system.

Inclusion Criteria:

• Provision of informed consent
• American Society of Anesthesiologists physical status I-III
• Average daily VAS ≥ 4
• Aged 18 - 75 years
• Male or female
• Scheduled for total hip arthroplasty (THA).

Exclusion Criteria:

• Allergy to study medications or local anesthetics
• History of drug or alcohol abuse
• Patients with chronic pain on slow-release preparations of opioid (>30mg morphine equivalent per day)
• Patients with rheumatoid arthritis
• Patients with psychiatric disorders
• Patients unable or unwilling to use Patient Controlled Analgesia (PCA).
• Diabetic patients or those with impaired renal function (Creatinine > 55)
• Obese patients (i.e. BMI > 40).