Cannabinoids vs. Placebo on Persistent Post-surgical Pain Following TKA: A Pilot RCT

Each year, approximately 75,000 Canadians undergo knee replacement surgery, and up to 25% develop persistent post-surgical pain. Persistent post-surgical pain is associated with depression, anxiety, unemployment, and reduced quality of life. Chronic pain after surgery is often managed with opioid therapy, which typically provides only modest benefits and is associated with rare but serious adverse events, such as overdose and death. A number of studies have found that greater pain just before and after knee replacement surgery is associated with the development of chronic pain, suggesting that reducing peri-operative pain may help prevent persistent post-surgical pain. Medicinal cannabis has begun to emerge as a potential therapy for pain reduction, and produces effects largely due to 2 active components: (1) cannabidiol (CBD), and (2) tetrahydrocannabinol (THC). Studies of CBD have shown analgesic, anti-inflammatory, and anti-anxiety properties, but without the psychoactive effects (feeling 'high') that THC produces. This study will assess the feasibility of a definitive trial to explore whether adding CBD dominant vs. placebo to usual care before and after surgery can reduce the rate of persistent post-surgical pain after total knee replacement. This study will randomize 40 patients to receive either CBD dominant or placebo, and follow them for six months to confirm our ability to recruit patients, adhere to protocol, and capture full outcome data for at least 85% of patients.