There is little published evidence regarding cannabis or cannabinoid use among orthopedic patients, yet there is increasing public attention on its possible role in treating various medical conditions including pain. California passed legislation legalizing cannabis for medical treatment in 2003 and recreational use in 2018. All patients undergoing total joint arthroplasty (TJA) at our institution are screened preoperatively with a urine toxicology (UTox) screen. Though a positive test for other substances triggers surgery cancellation, a positive screen for cannabis and/or opiates does not impact whether surgery is performed. We sought to quantify the prevalence of cannabinoid and opioid use among patients with chronic pain from end-stage hip and knee osteoarthritis who underwent arthroplasty at our institution in 2012 and 2017.
Institutional Review Board approval was obtained. A retrospective chart review was performed for all patients with severe arthritis who underwent total hip and knee arthroplasty (THA and TKA) at our institution during the calendar years 2012 and 2017. Patients were excluded if TJA was performed for acute trauma or if no pre-operative UTox screen was obtained. The UTox screen was used to determine preoperative cannabis and opioid use. Chi-squared testing was performed, and significance was defined as p<=0.05.
In the two years studied, 546 of 560 primary TJA surgeries (98%) had a pre-operative UTox screen performed. These 546 operations in 525 patients were reviewed (359 TKAs and 187 THAs). Comparing 2012 to 2017, the prevalence of preoperative cannabis use increased from 9% to 15% (p =.05) while the prevalence of opioid use decreased from 24% to 17% (p=.04). The proportion of patients who tested positive for both cannabis and opioids was low (3%) and did not change between 2012 and 2017 (p=.50). With the numbers available, patients who were using cannabis were no more or less likely to be taking opioids than non-cannabis users (p=.24).
Discussion and Conclusion
To our knowledge, this is the first study to identify the prevalence and trends of cannabis use in patients undergoing TJA. At our institution, cannabis use increased more than 60% while opioid use decreased about 30% over a 5-year interval. Whether these findings are related remains unclear. Future directions will include studying postoperative opioid requirements, disposition, complications, and readmissions in TJA patients who use cannabis.