Grant: Project Grant - PA: Institute of Musculoskeletal Health and Arthritis: Pain

With nearly 75,000 cases performed annually, total knee replacement (TKR) is among the most frequently performed surgical procedures in Canada, second only to Caesarean sections. Over 99% of TKR surgeries are performed specifically due to painful osteoarthritis (OA) of the knee. Although knee replacement surgery is generally associated with favourable outcomes for improving pain and disability caused by knee OA, approximately 1 in every 5 patients (20%) experience persistent knee pain after the procedure. This not only results in dissatisfaction, but often, functional limitations and the ongoing need for pain medication. Furthermore, it routinely leads to additional health care resources, including investigations (blood tests, radiographs, advanced imaging) and frequent visits to health care providers. The exact cause of persistent pain after TKR is challenging to determine, but typically is thought to be 'nerve related'. Even with an established diagnosis, treatment options are limited, and at best, usually provide only incremental benefit. As such, it would be high yield to identify interventions that can prevent persistent postoperative pain before it occurs. Vitamin C, also known as ascorbic acid, is a water-soluble vitamin that is essential in several biological processes, including those related to pain. Large population studies suggest that even mild decreases in vitamin C below normal range, are associated with musculoskeletal pain and functional impairments. Interestingly, it has been shown that vitamin C levels drop significantly after TKR surgery and there is evidence that administering vitamin C around the time of surgery may reduce persistent pain. However, the evidence to date has not been compelling enough to change practice. Our objective is to conduct a pilot randomized controlled trial to evaluate the effect of perioperative vitamin C administration on postoperative pain and function, in adult patients undergoing elective TKR surgery.