Cannabinol for Knee Replacement Surgery (COPE Trial)

Total knee replacement is a major and painful orthopaedic (joint and bone) surgery where the knee joint is replaced with an artificial joint. It is an effective and successful procedure to treat severe knee arthritis and reduce pain, but many patients report intense pain after the surgery. Postoperative pain control is predominated by opioids (morphine-based drugs). While opioids are effective to manage the pain, they can have acute and chronic complications, including confusion, nausea, vomiting, constipation and high risk of addiction. Medical cannabis is an effective and safe alternative for pain treatment. Recent studies showed that patients have reported a reduction in opioid usage when taking cannabis as a substitute for pain relief. This study aims to investigate whether adding medical cannabis (cannabidiol - CBD) treatment will decrease the amount of opiates needed in the first 2 weeks after knee replacement compared to a group given placebo.